//-----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All Rights Reserved.
//
//-----------------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Numerics;
using System.Diagnostics.Contracts;
using Microsoft.Boogie;
namespace Microsoft.Dafny {
public class Resolver {
public int ErrorCount = 0;
void Error(IToken tok, string msg, params object[] args) {
Contract.Requires(tok != null);
Contract.Requires(msg != null);
ConsoleColor col = Console.ForegroundColor;
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("{0}({1},{2}): Error: {3}",
tok.filename, tok.line, tok.col-1,
string.Format(msg, args));
Console.ForegroundColor = col;
ErrorCount++;
}
void Error(Declaration d, string msg, params object[] args) {
Contract.Requires(d != null);
Contract.Requires(msg != null);
Error(d.tok, msg, args);
}
void Error(Statement s, string msg, params object[] args) {
Contract.Requires(s != null);
Contract.Requires(msg != null);
Error(s.Tok, msg, args);
}
void Error(NonglobalVariable v, string msg, params object[] args) {
Contract.Requires(v != null);
Contract.Requires(msg != null);
Error(v.tok, msg, args);
}
void Error(Expression e, string msg, params object[] args) {
Contract.Requires(e != null);
Contract.Requires(msg != null);
Error(e.tok, msg, args);
}
void Warning(IToken tok, string msg, params object[] args) {
Contract.Requires(tok != null);
Contract.Requires(msg != null);
ConsoleColor col = Console.ForegroundColor;
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("{0}({1},{2}): Warning: {3}",
tok.filename, tok.line, tok.col - 1,
string.Format(msg, args));
Console.ForegroundColor = col;
}
readonly BuiltIns builtIns;
readonly Dictionary/*!*/ classes = new Dictionary();
readonly Dictionary/*!*/>/*!*/ classMembers = new Dictionary/*!*/>();
readonly Dictionary/*!*/>/*!*/ datatypeMembers = new Dictionary/*!*/>();
readonly Dictionary/*!*/>/*!*/ datatypeCtors = new Dictionary/*!*/>();
readonly Dictionary> allDatatypeCtors = new Dictionary>();
readonly Graph/*!*/ importGraph = new Graph();
public Resolver(Program prog) {
Contract.Requires(prog != null);
builtIns = prog.BuiltIns;
}
[ContractInvariantMethod]
void ObjectInvariant() {
Contract.Invariant(builtIns != null);
Contract.Invariant(cce.NonNullDictionaryAndValues(classes));
Contract.Invariant(cce.NonNullElements(importGraph));
Contract.Invariant(cce.NonNullDictionaryAndValues(classMembers) && Contract.ForAll(classMembers.Values, v => cce.NonNullDictionaryAndValues(v)));
Contract.Invariant(cce.NonNullDictionaryAndValues(datatypeCtors) && Contract.ForAll(datatypeCtors.Values, v => cce.NonNullDictionaryAndValues(v)));
}
bool checkRefinements = true; // used to indicate a cycle in refinements
public void ResolveProgram(Program prog) {
Contract.Requires(prog != null);
// register modules
Dictionary modules = new Dictionary();
foreach (ModuleDecl m in prog.Modules) {
if (modules.ContainsKey(m.Name)) {
Error(m, "Duplicate module name: {0}", m.Name);
} else {
modules.Add(m.Name, m);
}
}
// resolve imports and register top-level declarations
RegisterTopLevelDecls(prog.BuiltIns.SystemModule.TopLevelDecls);
Graph refines = new Graph();
foreach (ModuleDecl m in prog.Modules) {
importGraph.AddVertex(m);
foreach (string imp in m.Imports) {
ModuleDecl other;
if (!modules.TryGetValue(imp, out other)) {
Error(m, "module {0} named among imports does not exist", imp);
} else if (other == m) {
Error(m, "module must not import itself: {0}", imp);
} else {
Contract.Assert(other != null); // follows from postcondition of TryGetValue
importGraph.AddEdge(m, other);
}
}
RegisterTopLevelDecls(m.TopLevelDecls);
foreach (TopLevelDecl decl in m.TopLevelDecls) {Contract.Assert(decl != null); refines.AddVertex(decl);}
}
// check for cycles in the import graph
List cycle = importGraph.TryFindCycle();
if (cycle != null) {
string cy = "";
string sep = "";
foreach (ModuleDecl m in cycle) {
cy = m.Name + sep + cy;
sep = " -> ";
}
Error(cycle[0], "import graph contains a cycle: {0}", cy);
} else {
// fill in module heights
List mm = importGraph.TopologicallySortedComponents();
Contract.Assert(mm.Count == prog.Modules.Count); // follows from the fact that there are no cycles
int h = 0;
foreach (ModuleDecl m in mm) {
m.Height = h;
h++;
}
}
// resolve top-level declarations of refinements
foreach (ModuleDecl m in prog.Modules)
foreach (TopLevelDecl decl in m.TopLevelDecls)
if (decl is ClassRefinementDecl) {
ClassRefinementDecl rdecl = (ClassRefinementDecl) decl;
ResolveTopLevelRefinement(rdecl);
if (rdecl.Refined != null) refines.AddEdge(rdecl, rdecl.Refined);
}
// attempt finding refinement cycles
List refinesCycle = refines.TryFindCycle();
if (refinesCycle != null) {
string cy = "";
string sep = "";
foreach (TopLevelDecl decl in refinesCycle) {
cy = decl + sep + cy;
sep = " -> ";
}
Error(refinesCycle[0], "Detected a cyclic refinement declaration: {0}", cy);
checkRefinements = false;
}
// resolve top-level declarations
Graph datatypeDependencies = new Graph();
foreach (ModuleDecl m in prog.Modules) {
ResolveTopLevelDecls_Signatures(m.TopLevelDecls, datatypeDependencies);
}
foreach (ModuleDecl m in prog.Modules) {
ResolveTopLevelDecls_Meat(m.TopLevelDecls, datatypeDependencies);
}
// compute IsRecursive bit for mutually recursive functions
foreach (ModuleDecl m in prog.Modules) {
foreach (TopLevelDecl decl in m.TopLevelDecls) {
ClassDecl cl = decl as ClassDecl;
if (cl != null) {
foreach (MemberDecl member in cl.Members) {
Function fn = member as Function;
if (fn != null && !fn.IsRecursive) { // note, self-recursion has already been determined
int n = m.CallGraph.GetSCCSize(fn);
if (2 <= n) {
// the function is mutually recursive (note, the SCC does not determine self recursion)
fn.IsRecursive = true;
}
}
}
}
}
}
}
public void RegisterTopLevelDecls(List declarations) {
Contract.Requires(declarations != null);
foreach (TopLevelDecl d in declarations) {
Contract.Assert(d != null);
// register the class/datatype name
if (classes.ContainsKey(d.Name)) {
Error(d, "Duplicate name of top-level declaration: {0}", d.Name);
} else {
classes.Add(d.Name, d);
}
if (d is ClassDecl) {
ClassDecl cl = (ClassDecl)d;
// register the names of the class members
Dictionary members = new Dictionary();
classMembers.Add(cl, members);
bool hasConstructor = false;
foreach (MemberDecl m in cl.Members) {
if (members.ContainsKey(m.Name)) {
Error(m, "Duplicate member name: {0}", m.Name);
} else {
members.Add(m.Name, m);
}
if (m is Constructor) {
hasConstructor = true;
}
}
cl.HasConstructor = hasConstructor;
} else {
DatatypeDecl dt = (DatatypeDecl)d;
// register the names of the constructors
Dictionary ctors = new Dictionary();
datatypeCtors.Add(dt, ctors);
// ... and of the other members
Dictionary members = new Dictionary();
datatypeMembers.Add(dt, members);
foreach (DatatypeCtor ctor in dt.Ctors) {
if (ctor.Name.EndsWith("?")) {
Error(ctor, "a datatype constructor name is not allowed to end with '?'");
} else if (ctors.ContainsKey(ctor.Name)) {
Error(ctor, "Duplicate datatype constructor name: {0}", ctor.Name);
} else {
ctors.Add(ctor.Name, ctor);
// create and add the query "method" (field, really)
string queryName = ctor.Name + "?";
var query = new SpecialField(ctor.tok, queryName, "_" + ctor.Name, "", "", false, false, Type.Bool, null);
query.EnclosingClass = dt; // resolve here
members.Add(queryName, query);
ctor.QueryField = query;
// also register the constructor name globally
Tuple pair;
if (allDatatypeCtors.TryGetValue(ctor.Name, out pair)) {
// mark it as a duplicate
allDatatypeCtors[ctor.Name] = new Tuple(pair.Item1, true);
} else {
// add new
allDatatypeCtors.Add(ctor.Name, new Tuple(ctor, false));
}
}
}
// add deconstructors now (that is, after the query methods have been added)
foreach (DatatypeCtor ctor in dt.Ctors) {
foreach (var formal in ctor.Formals) {
SpecialField dtor = null;
if (formal.HasName) {
if (members.ContainsKey(formal.Name)) {
Error(ctor, "Name of deconstructor is used by another member of the datatype: {0}", formal.Name);
} else {
dtor = new SpecialField(formal.tok, formal.Name, "dtor_" + formal.Name, "", "", false, false, formal.Type, null);
dtor.EnclosingClass = dt; // resolve here
members.Add(formal.Name, dtor);
}
}
ctor.Destructors.Add(dtor);
}
}
}
}
}
public void ResolveTopLevelRefinement(ClassRefinementDecl decl) {
Contract.Requires(decl != null);
if (!classes.ContainsKey(decl.RefinedClass.val)) {
Error(decl.RefinedClass, "Refined class declaration is missing: {0}", decl.RefinedClass.val);
} else {
TopLevelDecl a = classes[decl.RefinedClass.val];
if (!(a is ClassDecl)) {
Error(a, "Refined declaration is not a class declaration: {0}", a.Name);
return;
}
decl.Refined = cce.NonNull((ClassDecl) a);
// TODO: copy over remaining members of a
}
}
public void ResolveTopLevelDecls_Signatures(List/*!*/ declarations, Graph/*!*/ datatypeDependencies) {
Contract.Requires(declarations != null);
Contract.Requires(cce.NonNullElements(datatypeDependencies));
foreach (TopLevelDecl d in declarations) {
Contract.Assert(d != null);
allTypeParameters.PushMarker();
ResolveTypeParameters(d.TypeArgs, true, d);
if (d is ClassDecl) {
ResolveClassMemberTypes((ClassDecl)d);
} else {
ResolveCtorTypes((DatatypeDecl)d, datatypeDependencies);
}
allTypeParameters.PopMarker();
}
}
public void ResolveTopLevelDecls_Meat(List/*!*/ declarations, Graph/*!*/ datatypeDependencies) {
Contract.Requires(declarations != null);
Contract.Requires(cce.NonNullElements(datatypeDependencies));
foreach (TopLevelDecl d in declarations) {
Contract.Assert(d != null);
allTypeParameters.PushMarker();
ResolveTypeParameters(d.TypeArgs, false, d);
if (d is ClassDecl) {
ResolveClassMemberBodies((ClassDecl)d);
} else {
DatatypeDecl dtd = (DatatypeDecl)d;
if (datatypeDependencies.GetSCCRepresentative(dtd) == dtd) {
// do the following check once per SCC, so call it on each SCC representative
SccStratosphereCheck(dtd, datatypeDependencies);
}
}
allTypeParameters.PopMarker();
}
}
ClassDecl currentClass;
Function currentFunction;
readonly Scope/*!*/ allTypeParameters = new Scope();
readonly Scope/*!*/ scope = new Scope();
Scope/*!*/ labeledStatements = new Scope();
List loopStack = new List(); // the enclosing loops (from which it is possible to break out)
readonly Dictionary inSpecOnlyContext = new Dictionary(); // invariant: domain contain union of the domains of "labeledStatements" and "loopStack"
///
/// Assumes type parameters have already been pushed
///
void ResolveClassMemberTypes(ClassDecl/*!*/ cl)
{
Contract.Requires(cl != null);
Contract.Requires(currentClass == null);
Contract.Ensures(currentClass == null);
currentClass = cl;
foreach (MemberDecl member in cl.Members) {
member.EnclosingClass = cl;
if (member is Field) {
ResolveType(member.tok, ((Field)member).Type);
} else if (member is Function) {
Function f = (Function)member;
allTypeParameters.PushMarker();
ResolveTypeParameters(f.TypeArgs, true, f);
ResolveFunctionSignature(f);
allTypeParameters.PopMarker();
} else if (member is Method) {
Method m = (Method)member;
allTypeParameters.PushMarker();
ResolveTypeParameters(m.TypeArgs, true, m);
ResolveMethodSignature(m);
allTypeParameters.PopMarker();
} else if (member is CouplingInvariant) {
CouplingInvariant inv = (CouplingInvariant)member;
if (currentClass is ClassRefinementDecl) {
ClassDecl refined = ((ClassRefinementDecl)currentClass).Refined;
if (refined != null) {
Contract.Assert(classMembers.ContainsKey(refined));
Dictionary members = classMembers[refined];
// resolve abstracted fields in the refined class
List fields = new List();
foreach (IToken tok in inv.Toks) {
if (!members.ContainsKey(tok.val))
Error(tok, "Refined class does not declare a field: {0}", tok.val);
else {
MemberDecl field = members[tok.val];
if (!(field is Field))
Error(tok, "Coupling invariant refers to a non-field member: {0}", tok.val);
else if (fields.Contains(cce.NonNull((Field)field)))
Error(tok, "Duplicate reference to a field in the refined class: {0}", tok.val);
else
fields.Add(cce.NonNull((Field)field));
}
}
inv.Refined = fields;
}
} else {
Error(member, "Coupling invariants can only be declared in refinement classes");
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected member type
}
if (currentClass is ClassRefinementDecl) {
ClassDecl refined = ((ClassRefinementDecl)currentClass).Refined;
if (refined != null) {
Contract.Assert(classMembers.ContainsKey(refined));
// there is a member with the same name in refined class if and only if the member is a refined method
if ((member is MethodRefinement) != (classMembers[refined].ContainsKey(member.Name)))
Error(member, "Refined class has a member with the same name as in the refinement class: {0}", member.Name);
}
}
}
currentClass = null;
}
///
/// Assumes type parameters have already been pushed, and that all types in class members have been resolved
///
void ResolveClassMemberBodies(ClassDecl cl)
{
Contract.Requires(cl != null);
Contract.Requires(currentClass == null);
Contract.Ensures(currentClass == null);
ResolveAttributes(cl.Attributes, false);
currentClass = cl;
foreach (MemberDecl member in cl.Members) {
if (member is Field) {
ResolveAttributes(member.Attributes, false);
// nothing more to do
} else if (member is Function) {
Function f = (Function)member;
allTypeParameters.PushMarker();
ResolveTypeParameters(f.TypeArgs, false, f);
ResolveFunction(f);
allTypeParameters.PopMarker();
} else if (member is Method) {
Method m = (Method)member;
allTypeParameters.PushMarker();
ResolveTypeParameters(m.TypeArgs, false, m);
ResolveMethod(m);
allTypeParameters.PopMarker();
// check if signature of the refined method matches the refinement method
if (member is MethodRefinement) {
MethodRefinement mf = (MethodRefinement)member;
if (currentClass is ClassRefinementDecl) {
// should have already been resolved
if (((ClassRefinementDecl)currentClass).Refined != null) {
MemberDecl d = classMembers[((ClassRefinementDecl)currentClass).Refined][mf.Name];
if (d is Method) {
mf.Refined = (Method)d;
if (mf.Ins.Count != mf.Refined.Ins.Count)
Error(mf, "Different number of input variables");
if (mf.Outs.Count != mf.Refined.Outs.Count)
Error(mf, "Different number of output variables");
if (mf.IsStatic || mf.Refined.IsStatic)
Error(mf, "Refined methods cannot be static");
} else {
Error(member, "Refined class has a non-method member with the same name: {0}", member.Name);
}
}
} else {
Error(member, "Refinement methods can only be declared in refinement classes: {0}", member.Name);
}
}
} else if (member is CouplingInvariant) {
CouplingInvariant inv = (CouplingInvariant)member;
ResolveAttributes(member.Attributes, false);
if (inv.Refined != null) {
inv.Formals = new List();
scope.PushMarker();
for (int i = 0; i < inv.Refined.Count; i++) {
Field field = inv.Refined[i];
Contract.Assert(field != null);
Formal formal = new Formal(inv.Toks[i], field.Name, field.Type, true, field.IsGhost);
Contract.Assert(formal != null);
inv.Formals.Add(formal);
scope.Push(inv.Toks[i].val, formal);
}
ResolveExpression(inv.Expr, false);
scope.PopMarker();
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected member type
}
}
currentClass = null;
}
///
/// Assumes type parameters have already been pushed
///
void ResolveCtorTypes(DatatypeDecl/*!*/ dt, Graph/*!*/ dependencies)
{
Contract.Requires(dt != null);
Contract.Requires(cce.NonNullElements(dependencies));
foreach (DatatypeCtor ctor in dt.Ctors) {
ctor.EnclosingDatatype = dt;
allTypeParameters.PushMarker();
ResolveCtorSignature(ctor);
allTypeParameters.PopMarker();
foreach (Formal p in ctor.Formals) {
DatatypeDecl dependee = p.Type.AsDatatype;
if (dependee != null) {
dependencies.AddEdge(dt, dependee);
}
}
}
}
///
/// Check that the SCC of 'startingPoint' can be carved up into stratospheres in such a way that each
/// datatype has some value that can be constructed from datatypes in lower stratospheres only.
/// The algorithm used here is quadratic in the number of datatypes in the SCC. Since that number is
/// deemed to be rather small, this seems okay.
///
void SccStratosphereCheck(DatatypeDecl startingPoint, Graph/*!*/ dependencies)
{
Contract.Requires(startingPoint != null);
Contract.Requires(cce.NonNullElements(dependencies));
List scc = dependencies.GetSCC(startingPoint);
List cleared = new List(); // this is really a set
while (true) {
int clearedThisRound = 0;
foreach (DatatypeDecl dt in scc) {
if (cleared.Contains(dt)) {
// previously cleared
} else if (StratosphereCheck(dt, dependencies, cleared)) {
clearedThisRound++;
cleared.Add(dt);
// (it would be nice if the List API allowed us to remove 'dt' from 'scc' here; then we wouldn't have to check 'cleared.Contains(dt)' above and below)
}
}
if (cleared.Count == scc.Count) {
// all is good
return;
} else if (clearedThisRound != 0) {
// some progress was made, so let's keep going
} else {
// whatever is in scc-cleared now failed to pass the test
foreach (DatatypeDecl dt in scc) {
if (!cleared.Contains(dt)) {
Error(dt, "because of cyclic dependencies among constructor argument types, no instances of datatype '{0}' can be constructed", dt.Name);
}
}
return;
}
}
}
///
/// Check that the datatype has some constructor all whose argument types go to a lower stratum, which means
/// go to a different SCC or to a type in 'goodOnes'.
/// Returns 'true' and sets dt.DefaultCtor if that is the case.
///
bool StratosphereCheck(DatatypeDecl dt, Graph/*!*/ dependencies, List/*!*/ goodOnes) {
Contract.Requires(dt != null);
Contract.Requires(cce.NonNullElements(dependencies));
Contract.Requires(cce.NonNullElements(goodOnes));
// Stated differently, check that there is some constuctor where no argument type goes to the same stratum.
DatatypeDecl stratumRepresentative = dependencies.GetSCCRepresentative(dt);
foreach (DatatypeCtor ctor in dt.Ctors) {
foreach (Formal p in ctor.Formals) {
DatatypeDecl dependee = p.Type.AsDatatype;
if (dependee == null) {
// the type is not a datatype, which means it's in the lowest stratum (below all datatypes)
} else if (dependencies.GetSCCRepresentative(dependee) != stratumRepresentative) {
// the argument type goes to a different stratum, which must be a "lower" one, so this argument is fine
} else if (goodOnes.Contains(dependee)) {
// the argument type is in the same SCC, but has already passed the test, so it is to be considered as
// being in a lower stratum
} else {
// the argument type is in the same stratum as 'dt', so this constructor is not what we're looking for
goto NEXT_OUTER_ITERATION;
}
}
// this constructor satisfies the requirements, so the datatype is allowed
dt.DefaultCtor = ctor;
return true;
NEXT_OUTER_ITERATION: {}
}
// no constructor satisfied the requirements, so this is an illegal datatype declaration
return false;
}
void ResolveAttributes(Attributes attrs, bool twoState) {
// order does not matter for resolution, so resolve them in reverse order
for (; attrs != null; attrs = attrs.Prev) {
ResolveAttributeArgs(attrs.Args, twoState);
}
}
void ResolveAttributeArgs(List/*!*/ args, bool twoState) {
Contract.Requires(args != null);
foreach (Attributes.Argument aa in args) {
Contract.Assert(aa != null);
if (aa.E != null) {
ResolveExpression(aa.E, twoState);
}
}
}
void ResolveTypeParameters(List/*!*/ tparams, bool emitErrors, TypeParameter.ParentType/*!*/ parent) {
Contract.Requires(tparams != null);
Contract.Requires(parent != null);
// push type arguments of the refined class
if (checkRefinements && parent is ClassRefinementDecl) {
ClassDecl refined = ((ClassRefinementDecl)parent).Refined;
if (refined != null)
ResolveTypeParameters(refined.TypeArgs, false, refined);
}
// push non-duplicated type parameter names
foreach (TypeParameter tp in tparams) {
Contract.Assert(tp != null);
if (emitErrors) {
// we're seeing this TypeParameter for the first time
tp.Parent = parent;
}
if (!allTypeParameters.Push(tp.Name, tp) && emitErrors) {
Error(tp, "Duplicate type-parameter name: {0}", tp.Name);
}
}
}
///
/// Assumes type parameters have already been pushed
///
void ResolveFunctionSignature(Function f) {
Contract.Requires(f != null);
scope.PushMarker();
foreach (Formal p in f.Formals) {
if (!scope.Push(p.Name, p)) {
Error(p, "Duplicate parameter name: {0}", p.Name);
}
ResolveType(p.tok, p.Type);
}
ResolveType(f.tok, f.ResultType);
scope.PopMarker();
}
///
/// Assumes type parameters have already been pushed
///
void ResolveFunction(Function f){
Contract.Requires(f != null);
Contract.Requires(currentFunction == null);
Contract.Ensures(currentFunction == null);
scope.PushMarker();
currentFunction = f;
if (f.IsStatic) {
scope.AllowInstance = false;
}
foreach (Formal p in f.Formals) {
scope.Push(p.Name, p);
}
ResolveAttributes(f.Attributes, false);
foreach (Expression r in f.Req) {
ResolveExpression(r, false);
Contract.Assert(r.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(r.Type, Type.Bool)) {
Error(r, "Precondition must be a boolean (got {0})", r.Type);
}
}
foreach (FrameExpression fr in f.Reads) {
ResolveFrameExpression(fr, "reads");
}
foreach (Expression r in f.Ens) {
ResolveExpression(r, false); // since this is a function, the postcondition is still a one-state predicate
Contract.Assert(r.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(r.Type, Type.Bool)) {
Error(r, "Postcondition must be a boolean (got {0})", r.Type);
}
}
foreach (Expression r in f.Decreases) {
ResolveExpression(r, false);
// any type is fine
}
if (f.Body != null) {
List matchVarContext = new List(f.Formals);
ResolveExpression(f.Body, false, matchVarContext);
if (!f.IsGhost) {
CheckIsNonGhost(f.Body);
}
Contract.Assert(f.Body.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(f.Body.Type, f.ResultType)) {
Error(f, "Function body type mismatch (expected {0}, got {1})", f.ResultType, f.Body.Type);
}
}
currentFunction = null;
scope.PopMarker();
}
void ResolveFrameExpression(FrameExpression fe, string kind) {
Contract.Requires(fe != null);
Contract.Requires(kind != null);
ResolveExpression(fe.E, false);
Type t = fe.E.Type;
Contract.Assert(t != null); // follows from postcondition of ResolveExpression
if (t is CollectionType) {
t = ((CollectionType)t).Arg;
}
if (t is ObjectType) {
// fine, as long as there's no field name
if (fe.FieldName != null) {
Error(fe.E, "type '{0}' does not contain a field named '{1}'", t, fe.FieldName);
}
} else if (UserDefinedType.DenotesClass(t) != null) {
// fine type
if (fe.FieldName != null) {
NonProxyType nptype;
MemberDecl member = ResolveMember(fe.E.tok, t, fe.FieldName, out nptype);
UserDefinedType ctype = (UserDefinedType)nptype; // correctness of cast follows from the DenotesClass test above
if (member == null) {
// error has already been reported by ResolveMember
} else if (!(member is Field)) {
Error(fe.E, "member {0} in type {1} does not refer to a field", fe.FieldName, cce.NonNull(ctype).Name);
} else {
Contract.Assert(ctype != null && ctype.ResolvedClass != null); // follows from postcondition of ResolveMember
fe.Field = (Field)member;
}
}
} else {
Error(fe.E, "a {0}-clause expression must denote an object or a collection of objects (instead got {1})", kind, fe.E.Type);
}
}
///
/// Assumes type parameters have already been pushed
///
void ResolveMethodSignature(Method m) {
Contract.Requires(m != null);
scope.PushMarker();
// resolve in-parameters
foreach (Formal p in m.Ins) {
if (!scope.Push(p.Name, p)) {
Error(p, "Duplicate parameter name: {0}", p.Name);
}
ResolveType(p.tok, p.Type);
}
// resolve out-parameters
foreach (Formal p in m.Outs) {
if (!scope.Push(p.Name, p)) {
Error(p, "Duplicate parameter name: {0}", p.Name);
}
ResolveType(p.tok, p.Type);
}
scope.PopMarker();
}
///
/// Assumes type parameters have already been pushed
///
void ResolveMethod(Method m) {
Contract.Requires(m != null);
// Add in-parameters to the scope, but don't care about any duplication errors, since they have already been reported
scope.PushMarker();
if (m.IsStatic) {
scope.AllowInstance = false;
}
foreach (Formal p in m.Ins) {
scope.Push(p.Name, p);
}
// Start resolving specification...
foreach (MaybeFreeExpression e in m.Req) {
ResolveExpression(e.E, false);
Contract.Assert(e.E.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.E.Type, Type.Bool)) {
Error(e.E, "Precondition must be a boolean (got {0})", e.E.Type);
}
}
foreach (FrameExpression fe in m.Mod) {
ResolveFrameExpression(fe, "modifies");
}
foreach (Expression e in m.Decreases) {
ResolveExpression(e, false);
// any type is fine
}
// Add out-parameters to a new scope that will also include the outermost-level locals of the body
// Don't care about any duplication errors among the out-parameters, since they have already been reported
scope.PushMarker();
foreach (Formal p in m.Outs) {
scope.Push(p.Name, p);
}
// attributes are allowed to mention both in- and out-parameters
ResolveAttributes(m.Attributes, false);
// ... continue resolving specification
bool twoState = true;
if (m.Mod.Count == 0 && m.Outs.Count == 0) {
// In this special case, the current translation of parallel Call statements would be unsound.
// The reason is that the parallel Call statement does not advance the heap, so there had better
// not be any way to say that the post-heap is definitely different than the pre-heap. For example,
// the following program, is permitted, would unsoundly verify:
// ghost static method M(y: int)
// ensures exists o: object :: o != null && fresh(o);
// {
// var p := new object;
// }
// method Main() {
// parallel (x) { M(x); }
// assert false;
// }
// In fact, here is another method M that together with Main above would yield unsound verification:
// class C { ghost var data: int; }
// ghost static method M(y: int)
// ensures exists c: C :: c != null && c.data != old(c.data);
// {
// var c := new C;
// c.data := c.data + 1;
// }
// So, it seems best just to disallow two-state postconditions in these cases. Perhaps the error
// message will not explain enough of the reasons for this restriction, but the restriction does
// not seem to rule out any useful programs.
twoState = false;
}
foreach (MaybeFreeExpression e in m.Ens) {
ResolveExpression(e.E, twoState);
Contract.Assert(e.E.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.E.Type, Type.Bool)) {
Error(e.E, "Postcondition must be a boolean (got {0})", e.E.Type);
}
}
// Resolve body
if (m.Body != null) {
ResolveBlockStatement(m.Body, m.IsGhost, m);
}
scope.PopMarker(); // for the out-parameters and outermost-level locals
scope.PopMarker(); // for the in-parameters
}
void ResolveCtorSignature(DatatypeCtor ctor) {
Contract.Requires(ctor != null);
foreach (Formal p in ctor.Formals) {
ResolveType(p.tok, p.Type);
}
}
public void ResolveType(IToken tok, Type type) {
Contract.Requires(type != null);
if (type is BasicType) {
// nothing to resolve
} else if (type is CollectionType) {
var t = (CollectionType)type;
var argType = t.Arg;
ResolveType(tok, argType);
if (argType.IsSubrangeType) {
Error(tok, "sorry, cannot instantiate collection type with a subrange type");
}
} else if (type is UserDefinedType) {
UserDefinedType t = (UserDefinedType)type;
foreach (Type tt in t.TypeArgs) {
ResolveType(t.tok, tt);
if (tt.IsSubrangeType) {
Error(t.tok, "sorry, cannot instantiate type parameter with a subrange type");
}
}
TypeParameter tp = allTypeParameters.Find(t.Name);
if (tp != null) {
if (t.TypeArgs.Count == 0) {
t.ResolvedParam = tp;
} else {
Error(t.tok, "Type parameter expects no type arguments: {0}", t.Name);
}
} else if (t.ResolvedClass == null) { // this test is because 'array' is already resolved; TODO: an alternative would be to pre-populate 'classes' with built-in references types like 'array' (and perhaps in the future 'string')
TopLevelDecl d;
if (!classes.TryGetValue(t.Name, out d)) {
Error(t.tok, "Undeclared top-level type or type parameter: {0}", t.Name);
} else if (cce.NonNull(d).TypeArgs.Count == t.TypeArgs.Count) {
t.ResolvedClass = d;
} else {
Error(t.tok, "Wrong number of type arguments ({0} instead of {1}) passed to class/datatype: {2}", t.TypeArgs.Count, d.TypeArgs.Count, t.Name);
}
}
} else if (type is TypeProxy) {
TypeProxy t = (TypeProxy)type;
if (t.T != null) {
ResolveType(tok, t.T);
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected type
}
}
public bool UnifyTypes(Type a, Type b) {
Contract.Requires(a != null);
Contract.Requires(b != null);
while (a is TypeProxy) {
TypeProxy proxy = (TypeProxy)a;
if (proxy.T == null) {
// merge a and b; to avoid cycles, first get to the bottom of b
while (b is TypeProxy && ((TypeProxy)b).T != null) {
b = ((TypeProxy)b).T;
}
return AssignProxy(proxy, b);
} else {
a = proxy.T;
}
}
while (b is TypeProxy) {
TypeProxy proxy = (TypeProxy)b;
if (proxy.T == null) {
// merge a and b (we have already got to the bottom of a)
return AssignProxy(proxy, a);
} else {
b = proxy.T;
}
}
#if !NO_CHEAP_OBJECT_WORKAROUND
if (a is ObjectType || b is ObjectType) { // TODO: remove this temporary hack
var other = a is ObjectType ? b : a;
if (other is BoolType || other is IntType || other is SetType || other is SeqType || other.IsDatatype) {
return false;
}
// allow anything else with object; this is BOGUS
return true;
}
#endif
// Now, a and b are non-proxies and stand for the same things as the original a and b, respectively.
if (a is BoolType) {
return b is BoolType;
} else if (a is IntType) {
return b is IntType;
} else if (a is ObjectType) {
return b is ObjectType;
} else if (a is SetType) {
return b is SetType && UnifyTypes(((SetType)a).Arg, ((SetType)b).Arg);
} else if (a is MultiSetType) {
return b is MultiSetType && UnifyTypes(((MultiSetType)a).Arg, ((MultiSetType)b).Arg);
} else if (a is SeqType) {
return b is SeqType && UnifyTypes(((SeqType)a).Arg, ((SeqType)b).Arg);
} else if (a is UserDefinedType) {
if (!(b is UserDefinedType)) {
return false;
}
UserDefinedType aa = (UserDefinedType)a;
UserDefinedType bb = (UserDefinedType)b;
if (aa.ResolvedClass != null && aa.ResolvedClass == bb.ResolvedClass) {
// these are both resolved class/datatype types
Contract.Assert(aa.TypeArgs.Count == bb.TypeArgs.Count);
bool successSoFar = true;
for (int i = 0; i < aa.TypeArgs.Count; i++) {
if (!UnifyTypes(aa.TypeArgs[i], bb.TypeArgs[i])) {
successSoFar = false;
}
}
return successSoFar;
} else if (aa.ResolvedParam != null && aa.ResolvedParam == bb.ResolvedParam) {
// these are both resolved type parameters
Contract.Assert(aa.TypeArgs.Count == 0 && bb.TypeArgs.Count == 0);
return true;
} else {
// something is wrong; either aa or bb wasn't properly resolved, or they don't unify
return false;
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected type
}
}
bool AssignProxy(TypeProxy proxy, Type t){
Contract.Requires(proxy != null);
Contract.Requires(t != null);
Contract.Requires(proxy.T == null);
Contract.Requires(!(t is TypeProxy) || ((TypeProxy)t).T == null);
//modifies proxy.T, ((TypeProxy)t).T; // might also change t.T if t is a proxy
Contract.Ensures(Contract.Result() == (proxy == t || proxy.T != null || (t is TypeProxy && ((TypeProxy)t).T != null)));
if (proxy == t) {
// they are already in the same equivalence class
return true;
} else if (proxy is UnrestrictedTypeProxy) {
// it's fine to redirect proxy to t (done below)
} else if (t is UnrestrictedTypeProxy) {
// merge proxy and t by redirecting t to proxy, rather than the other way around
((TypeProxy)t).T = proxy;
return true;
} else if (t is RestrictedTypeProxy) {
// Both proxy and t are restricted type proxies. To simplify unification, order proxy and t
// according to their types.
RestrictedTypeProxy r0 = (RestrictedTypeProxy)proxy;
RestrictedTypeProxy r1 = (RestrictedTypeProxy)t;
if (r0.OrderID <= r1.OrderID) {
return AssignRestrictedProxies(r0, r1);
} else {
return AssignRestrictedProxies(r1, r0);
}
// In the remaining cases, proxy is a restricted proxy and t is a non-proxy
} else if (proxy is DatatypeProxy) {
if (t.IsDatatype) {
// all is fine, proxy can be redirected to t
} else {
return false;
}
} else if (proxy is ObjectTypeProxy) {
if (t is ObjectType || UserDefinedType.DenotesClass(t) != null) {
// all is fine, proxy can be redirected to t
} else {
return false;
}
} else if (proxy is ObjectsTypeProxy) {
if (t is ObjectType || UserDefinedType.DenotesClass(t) != null) {
// all is good
} else if (t is CollectionType) {
proxy.T = new CollectionTypeProxy(new ObjectTypeProxy());
return UnifyTypes(proxy.T, t);
}
} else if (proxy is CollectionTypeProxy) {
CollectionTypeProxy collProxy = (CollectionTypeProxy)proxy;
if (t is CollectionType) {
if (!UnifyTypes(collProxy.Arg, ((CollectionType)t).Arg)) {
return false;
}
} else {
return false;
}
} else if (proxy is OperationTypeProxy) {
OperationTypeProxy opProxy = (OperationTypeProxy)proxy;
if (t is IntType || t is SetType || t is MultiSetType || (opProxy.AllowSeq && t is SeqType)) {
// this is the expected case
} else {
return false;
}
} else if (proxy is IndexableTypeProxy) {
IndexableTypeProxy iProxy = (IndexableTypeProxy)proxy;
if (t is SeqType) {
if (!UnifyTypes(iProxy.Arg, ((SeqType)t).Arg)) {
return false;
}
} else if (t.IsArrayType && (t.AsArrayType).Dims == 1) {
Type elType = UserDefinedType.ArrayElementType(t);
if (!UnifyTypes(iProxy.Arg, elType)) {
return false;
}
} else {
return false;
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected proxy type
}
// do the merge, but never infer a subrange type
if (t is NatType) {
proxy.T = Type.Int;
} else {
proxy.T = t;
}
return true;
}
bool AssignRestrictedProxies(RestrictedTypeProxy a, RestrictedTypeProxy b)
{ Contract.Requires(a != null);
Contract.Requires(b != null);
Contract.Requires(a != b);
Contract.Requires(a.T == null && b.T == null);
Contract.Requires(a.OrderID <= b.OrderID);
//modifies a.T, b.T;
Contract.Ensures(Contract.Result() || a.T != null || b.T != null);
if (a is DatatypeProxy) {
if (b is DatatypeProxy) {
// all is fine
a.T = b;
return true;
} else {
return false;
}
} else if (a is ObjectTypeProxy) {
if (b is ObjectTypeProxy) {
// all is fine
a.T = b;
return true;
} else if (b is ObjectsTypeProxy) {
// unify a and b by redirecting b to a, since a gives the stronger requirement
b.T = a;
return true;
} else if (b is IndexableTypeProxy) {
// the intersection of ObjectTypeProxy and IndexableTypeProxy is an array type
a.T = builtIns.ArrayType(1, ((IndexableTypeProxy)b).Arg);
b.T = a.T;
return true;
} else {
return false;
}
} else if (a is ObjectsTypeProxy) {
if (b is ObjectsTypeProxy) {
// fine
a.T = b;
return true;
} else if (b is CollectionTypeProxy) {
// fine provided b's collection-element-type can be unified with object or a class type
a.T = b;
return UnifyTypes(((CollectionTypeProxy)b).Arg, new ObjectTypeProxy());
} else if (b is OperationTypeProxy) {
// fine; restrict a to sets of object/class, and restrict b to set/seq of object/class
if (((OperationTypeProxy)b).AllowSeq) {
a.T = new CollectionTypeProxy(new ObjectTypeProxy());
b.T = a.T;
} else {
a.T = new SetType(new ObjectTypeProxy());
b.T = a.T;
}
return true;
} else if (b is IndexableTypeProxy) {
IndexableTypeProxy pb = (IndexableTypeProxy)b;
// the intersection of ObjectsTypeProxy and IndexableTypeProxy is
// EITHER a sequence of ObjectTypeProxy OR an array of anything
// TODO: here, only the first of the two cases is supported
b.T = new SeqType(pb.Arg);
a.T = b.T;
return UnifyTypes(pb.Arg, new ObjectTypeProxy());
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected restricted-proxy type
}
} else if (a is CollectionTypeProxy) {
if (b is CollectionTypeProxy) {
a.T = b;
return UnifyTypes(((CollectionTypeProxy)a).Arg, ((CollectionTypeProxy)b).Arg);
} else if (b is OperationTypeProxy) {
if (((OperationTypeProxy)b).AllowSeq) {
b.T = a; // a is a stronger constraint than b
} else {
// a says set,seq and b says int,set; the intersection is set
a.T = new SetType(((CollectionTypeProxy)a).Arg);
b.T = a.T;
}
return true;
} else if (b is IndexableTypeProxy) {
CollectionTypeProxy pa = (CollectionTypeProxy)a;
IndexableTypeProxy pb = (IndexableTypeProxy)b;
// strengthen a and b to a sequence type
a.T = new SeqType(pa.Arg);
b.T = new SeqType(pb.Arg);
return UnifyTypes(pa.Arg, pb.Arg);
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected restricted-proxy type
}
} else if (a is OperationTypeProxy) {
OperationTypeProxy pa = (OperationTypeProxy)a;
if (b is OperationTypeProxy) {
if (!pa.AllowSeq || ((OperationTypeProxy)b).AllowSeq) {
b.T = a;
} else {
a.T = b; // b has the stronger requirement
}
return true;
} else {
IndexableTypeProxy pb = (IndexableTypeProxy)b; // cast justification: lse we have unexpected restricted-proxy type
if (pa.AllowSeq) {
// strengthen a and b to a sequence type
b.T = new SeqType(pb.Arg);
a.T = b.T;
return true;
} else {
return false;
}
}
} else if (a is IndexableTypeProxy) {
Contract.Assert(b is IndexableTypeProxy); // else we have unexpected restricted-proxy type
a.T = b;
return UnifyTypes(((IndexableTypeProxy)a).Arg, ((IndexableTypeProxy)b).Arg);
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected restricted-proxy type
}
}
///
/// "specContextOnly" means that the statement must be erasable, that is, it should be okay to omit it
/// at run time. That means it must not have any side effects on non-ghost variables, for example.
///
public void ResolveStatement(Statement stmt, bool specContextOnly, Method method) {
Contract.Requires(stmt != null);
Contract.Requires(method != null);
if (stmt is PredicateStmt) {
PredicateStmt s = (PredicateStmt)stmt;
s.IsGhost = true;
ResolveExpression(s.Expr, true);
Contract.Assert(s.Expr.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(s.Expr.Type, Type.Bool)) {
Error(s.Expr, "condition is expected to be of type {0}, but is {1}", Type.Bool, s.Expr.Type);
}
} else if (stmt is PrintStmt) {
PrintStmt s = (PrintStmt)stmt;
ResolveAttributeArgs(s.Args, false);
if (specContextOnly) {
Error(stmt, "print statement is not allowed in this context (because this is a ghost method or because the statement is guarded by a specification-only expression)");
}
} else if (stmt is BreakStmt) {
var s = (BreakStmt)stmt;
if (s.TargetLabel != null) {
Statement target = labeledStatements.Find(s.TargetLabel);
if (target == null) {
Error(s, "break label is undefined or not in scope: {0}", s.TargetLabel);
} else {
s.TargetStmt = target;
bool targetIsLoop = target is WhileStmt || target is AlternativeLoopStmt;
if (specContextOnly && !s.TargetStmt.IsGhost && !inSpecOnlyContext[s.TargetStmt]) {
Error(stmt, "ghost-context break statement is not allowed to break out of non-ghost " + (targetIsLoop ? "loop" : "structure"));
}
}
} else {
if (loopStack.Count < s.BreakCount) {
Error(s, "trying to break out of more loop levels than there are enclosing loops");
} else {
Statement target = loopStack[loopStack.Count - s.BreakCount];
if (target.Labels == null) {
// make sure there is a label, because the compiler and translator will want to see a unique ID
target.Labels = new LabelNode(target.Tok, null, null);
}
s.TargetStmt = target;
if (specContextOnly && !target.IsGhost && !inSpecOnlyContext[target]) {
Error(stmt, "ghost-context break statement is not allowed to break out of non-ghost loop");
}
}
}
} else if (stmt is ReturnStmt) {
if (specContextOnly && !method.IsGhost) {
// TODO: investigate. This error message is suspicious. It seems that a return statement is only
// disallowed from a ghost if or while in a non-ghost method, which is not what this says.
Error(stmt, "return statement is not allowed in this context (because this is a ghost method or because the statement is guarded by a specification-only expression)");
}
ReturnStmt s = (ReturnStmt) stmt;
if (s.rhss != null) {
if (method.Outs.Count != s.rhss.Count)
Error(s, "number of return parameters does not match declaration (found {0}, expected {1})", s.rhss.Count, method.Outs.Count);
else {
Contract.Assert(s.rhss.Count > 0);
// Create a hidden update statement using the out-parameter formals, resolve the RHS, and check that the RHS is good.
List formals = new List();
int i = 0;
foreach (Formal f in method.Outs) {
IdentifierExpr ident = new IdentifierExpr(f.tok, f.Name);
ident.Var = f;
ident.Type = ident.Var.Type;
Contract.Assert(f.Type != null);
formals.Add(ident);
// link the reciever parameter properly:
if (s.rhss[i] is TypeRhs) {
var r = (TypeRhs)s.rhss[i];
if (r.InitCall != null) {
r.InitCall.Receiver = ident;
}
}
i++;
}
s.hiddenUpdate = new UpdateStmt(s.Tok, formals, s.rhss, true);
// resolving the update statement will check for return statement specifics.
ResolveStatement(s.hiddenUpdate, specContextOnly, method);
}
}
else {// this is a regular return statement.
s.hiddenUpdate = null;
}
} else if (stmt is UpdateStmt) {
ResolveUpdateStmt((UpdateStmt)stmt, specContextOnly, method);
} else if (stmt is VarDeclStmt) {
var s = (VarDeclStmt)stmt;
foreach (var vd in s.Lhss) {
ResolveStatement(vd, specContextOnly, method);
s.ResolvedStatements.Add(vd);
}
if (s.Update != null) {
ResolveStatement(s.Update, specContextOnly, method);
s.ResolvedStatements.Add(s.Update);
}
} else if (stmt is AssignStmt) {
AssignStmt s = (AssignStmt)stmt;
int prevErrorCount = ErrorCount;
if (s.Lhs is SeqSelectExpr) {
ResolveSeqSelectExpr((SeqSelectExpr)s.Lhs, true, false); // allow ghosts for now, tighted up below
} else {
ResolveExpression(s.Lhs, true); // allow ghosts for now, tighted up below
}
bool lhsResolvedSuccessfully = ErrorCount == prevErrorCount;
Contract.Assert(s.Lhs.Type != null); // follows from postcondition of ResolveExpression
// check that LHS denotes a mutable variable or a field
bool lvalueIsGhost = false;
var lhs = s.Lhs.Resolved;
if (lhs is IdentifierExpr) {
IVariable var = ((IdentifierExpr)lhs).Var;
if (var == null) {
// the LHS didn't resolve correctly; some error would already have been reported
} else {
lvalueIsGhost = var.IsGhost || method.IsGhost;
if (!var.IsMutable) {
Error(stmt, "LHS of assignment must denote a mutable variable or field");
}
if (!lvalueIsGhost && specContextOnly) {
Error(stmt, "Assignment to non-ghost variable is not allowed in this context (because this is a ghost method or because the statement is guarded by a specification-only expression)");
}
}
} else if (lhs is FieldSelectExpr) {
var fse = (FieldSelectExpr)lhs;
if (fse.Field != null) { // otherwise, an error was reported above
lvalueIsGhost = fse.Field.IsGhost;
if (!lvalueIsGhost) {
if (specContextOnly) {
Error(stmt, "Assignment to non-ghost field is not allowed in this context (because this is a ghost method or because the statement is guarded by a specification-only expression)");
} else {
// It is now that we wish we would have resolved s.Lhs to not allow ghosts. Too late, so we do
// the next best thing.
if (lhsResolvedSuccessfully && UsesSpecFeatures(fse.Obj)) {
Error(stmt, "Assignment to non-ghost field is not allowed to use specification-only expressions in the receiver");
}
}
}
if (!fse.Field.IsMutable) {
Error(stmt, "LHS of assignment does not denote a mutable field");
}
}
} else if (lhs is SeqSelectExpr) {
var slhs = (SeqSelectExpr)lhs;
// LHS is fine, provided the "sequence" is really an array
if (lhsResolvedSuccessfully) {
Contract.Assert(slhs.Seq.Type != null);
if (!UnifyTypes(slhs.Seq.Type, builtIns.ArrayType(1, new InferredTypeProxy()))) {
Error(slhs.Seq, "LHS of array assignment must denote an array element (found {0})", slhs.Seq.Type);
}
if (specContextOnly) {
Error(stmt, "Assignment to array element is not allowed in this context (because this is a ghost method or because the statement is guarded by a specification-only expression)");
}
if (!slhs.SelectOne) {
Error(stmt, "cannot assign to a range of array elements (try the 'parallel' statement)");
}
}
} else if (lhs is MultiSelectExpr) {
if (specContextOnly) {
Error(stmt, "Assignment to array element is not allowed in this context (because this is a ghost method or because the statement is guarded by a specification-only expression)");
}
} else {
Error(stmt, "LHS of assignment must denote a mutable variable or field");
}
s.IsGhost = lvalueIsGhost;
Type lhsType = s.Lhs.Type;
if (lhs is SeqSelectExpr && !((SeqSelectExpr)lhs).SelectOne) {
Error(stmt, "cannot assign to a range of array elements (try the 'parallel' statement)");
//lhsType = UserDefinedType.ArrayElementType(lhsType);
} else {
if (s.Rhs is ExprRhs) {
ExprRhs rr = (ExprRhs)s.Rhs;
ResolveExpression(rr.Expr, true);
if (!lvalueIsGhost) {
CheckIsNonGhost(rr.Expr);
}
Contract.Assert(rr.Expr.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(lhsType, rr.Expr.Type)) {
Error(stmt, "RHS (of type {0}) not assignable to LHS (of type {1})", rr.Expr.Type, lhsType);
}
} else if (s.Rhs is TypeRhs) {
TypeRhs rr = (TypeRhs)s.Rhs;
Type t = ResolveTypeRhs(rr, stmt, lvalueIsGhost, method);
if (!lvalueIsGhost) {
if (rr.ArrayDimensions != null) {
foreach (var dim in rr.ArrayDimensions) {
CheckIsNonGhost(dim);
}
}
if (rr.InitCall != null) {
foreach (var arg in rr.InitCall.Args) {
CheckIsNonGhost(arg);
}
}
}
if (!UnifyTypes(lhsType, t)) {
Error(stmt, "type {0} is not assignable to LHS (of type {1})", t, lhsType);
}
} else if (s.Rhs is HavocRhs) {
// nothing else to do
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected RHS
}
}
} else if (stmt is VarDecl) {
VarDecl s = (VarDecl)stmt;
if (s.OptionalType != null) {
ResolveType(stmt.Tok, s.OptionalType);
s.type = s.OptionalType;
}
// now that the declaration has been processed, add the name to the scope
if (!scope.Push(s.Name, s)) {
Error(s, "Duplicate local-variable name: {0}", s.Name);
}
if (specContextOnly) {
// a local variable in a specification-only context might as well be ghost
s.IsGhost = true;
}
} else if (stmt is CallStmt) {
CallStmt s = (CallStmt)stmt;
ResolveCallStmt(s, specContextOnly, method, null);
} else if (stmt is BlockStmt) {
scope.PushMarker();
ResolveBlockStatement((BlockStmt)stmt, specContextOnly, method);
scope.PopMarker();
} else if (stmt is IfStmt) {
IfStmt s = (IfStmt)stmt;
bool branchesAreSpecOnly = specContextOnly;
if (s.Guard != null) {
int prevErrorCount = ErrorCount;
ResolveExpression(s.Guard, true);
Contract.Assert(s.Guard.Type != null); // follows from postcondition of ResolveExpression
bool successfullyResolved = ErrorCount == prevErrorCount;
if (!UnifyTypes(s.Guard.Type, Type.Bool)) {
Error(s.Guard, "condition is expected to be of type {0}, but is {1}", Type.Bool, s.Guard.Type);
}
if (!specContextOnly && successfullyResolved) {
branchesAreSpecOnly = UsesSpecFeatures(s.Guard);
}
}
s.IsGhost = branchesAreSpecOnly;
ResolveStatement(s.Thn, branchesAreSpecOnly, method);
if (s.Els != null) {
ResolveStatement(s.Els, branchesAreSpecOnly, method);
}
} else if (stmt is AlternativeStmt) {
var s = (AlternativeStmt)stmt;
s.IsGhost = ResolveAlternatives(s.Alternatives, specContextOnly, null, method);
} else if (stmt is WhileStmt) {
WhileStmt s = (WhileStmt)stmt;
bool bodyMustBeSpecOnly = specContextOnly;
if (s.Guard != null) {
int prevErrorCount = ErrorCount;
ResolveExpression(s.Guard, true);
Contract.Assert(s.Guard.Type != null); // follows from postcondition of ResolveExpression
bool successfullyResolved = ErrorCount == prevErrorCount;
if (!UnifyTypes(s.Guard.Type, Type.Bool)) {
Error(s.Guard, "condition is expected to be of type {0}, but is {1}", Type.Bool, s.Guard.Type);
}
if (!specContextOnly && successfullyResolved) {
bodyMustBeSpecOnly = UsesSpecFeatures(s.Guard);
}
}
foreach (MaybeFreeExpression inv in s.Invariants) {
ResolveExpression(inv.E, true);
Contract.Assert(inv.E.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(inv.E.Type, Type.Bool)) {
Error(inv.E, "invariant is expected to be of type {0}, but is {1}", Type.Bool, inv.E.Type);
}
}
foreach (Expression e in s.Decreases) {
ResolveExpression(e, true);
if (bodyMustBeSpecOnly && e is WildcardExpr) {
Error(e, "'decreases *' is not allowed on ghost loops");
}
// any type is fine
}
if(s.Mod != null) {
foreach (FrameExpression fe in s.Mod) {
ResolveFrameExpression(fe, "modifies");
}
}
s.IsGhost = bodyMustBeSpecOnly;
loopStack.Add(s); // push
if (s.Labels == null) { // otherwise, "s" is already in "inSpecOnlyContext" map
inSpecOnlyContext.Add(s, specContextOnly);
}
ResolveStatement(s.Body, bodyMustBeSpecOnly, method);
loopStack.RemoveAt(loopStack.Count-1); // pop
} else if (stmt is AlternativeLoopStmt) {
var s = (AlternativeLoopStmt)stmt;
s.IsGhost = ResolveAlternatives(s.Alternatives, specContextOnly, s, method);
foreach (MaybeFreeExpression inv in s.Invariants) {
ResolveExpression(inv.E, true);
Contract.Assert(inv.E.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(inv.E.Type, Type.Bool)) {
Error(inv.E, "invariant is expected to be of type {0}, but is {1}", Type.Bool, inv.E.Type);
}
}
foreach (Expression e in s.Decreases) {
ResolveExpression(e, true);
if (s.IsGhost && e is WildcardExpr) {
Error(e, "'decreases *' is not allowed on ghost loops");
}
// any type is fine
}
} else if (stmt is ParallelStmt) {
var s = (ParallelStmt)stmt;
int prevErrorCount = ErrorCount;
scope.PushMarker();
foreach (BoundVar v in s.BoundVars) {
if (!scope.Push(v.Name, v)) {
Error(v, "Duplicate bound-variable name: {0}", v.Name);
}
ResolveType(v.tok, v.Type);
}
ResolveExpression(s.Range, true);
Contract.Assert(s.Range.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(s.Range.Type, Type.Bool)) {
Error(stmt, "range restriction in parallel statement must be of type bool (instead got {0})", s.Range.Type);
}
foreach (var ens in s.Ens) {
ResolveExpression(ens.E, false); // Note, two-state features are not allowed (see the resolution of method postconditions in this file, and see the X_ examples in Test/dafny0/ParallelResolveErrors.dfy)
Contract.Assert(ens.E.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(ens.E.Type, Type.Bool)) {
Error(ens.E, "ensures condition is expected to be of type {0}, but is {1}", Type.Bool, ens.E.Type);
}
}
// Since the range and postconditions are more likely to infer the types of the bound variables, resolve them
// first (above) and only then resolve the attributes (below).
ResolveAttributes(s.Attributes, true);
bool bodyMustBeSpecOnly = specContextOnly || (prevErrorCount == ErrorCount && UsesSpecFeatures(s.Range));
if (!bodyMustBeSpecOnly && prevErrorCount == ErrorCount) {
var missingBounds = new List();
s.Bounds = DiscoverBounds(s.Tok, s.BoundVars, s.Range, true, missingBounds);
if (missingBounds.Count != 0) {
bodyMustBeSpecOnly = true;
}
}
s.IsGhost = bodyMustBeSpecOnly;
// clear the labels for the duration of checking the body, because break statements are not allowed to leave a parallel statement
var prevLblStmts = labeledStatements;
var prevLoopStack = loopStack;
labeledStatements = new Scope();
loopStack = new List();
ResolveStatement(s.Body, bodyMustBeSpecOnly, method);
labeledStatements = prevLblStmts;
loopStack = prevLoopStack;
scope.PopMarker();
if (prevErrorCount == ErrorCount) {
// determine the Kind and run some additional checks on the body
if (s.Ens.Count != 0) {
// The only supported kind with ensures clauses is Proof.
s.Kind = ParallelStmt.ParBodyKind.Proof;
} else {
// There are two special cases:
// * Assign, which is the only kind of the parallel statement that allows a heap update.
// * Call, which is a single call statement with no side effects or output parameters.
// The effect of Assign and the postcondition of Call will be seen outside the parallel
// statement.
Statement s0 = s.S0;
if (s0 is AssignStmt) {
s.Kind = ParallelStmt.ParBodyKind.Assign;
} else if (s0 is CallStmt) {
s.Kind = ParallelStmt.ParBodyKind.Call;
} else {
s.Kind = ParallelStmt.ParBodyKind.Proof;
if (s.Body is BlockStmt && ((BlockStmt)s.Body).Body.Count == 0) {
// an empty statement, so don't produce any warning
} else {
Warning(s.Tok, "the conclusion of the body of this parallel statement will not be known outside the parallel statement; consider using an 'ensures' clause");
}
}
}
CheckParallelBodyRestrictions(s.Body, s.Kind == ParallelStmt.ParBodyKind.Assign);
}
} else if (stmt is MatchStmt) {
MatchStmt s = (MatchStmt)stmt;
bool bodyIsSpecOnly = specContextOnly;
int prevErrorCount = ErrorCount;
ResolveExpression(s.Source, true);
Contract.Assert(s.Source.Type != null); // follows from postcondition of ResolveExpression
bool successfullyResolved = ErrorCount == prevErrorCount;
if (!specContextOnly && successfullyResolved) {
bodyIsSpecOnly = UsesSpecFeatures(s.Source);
}
UserDefinedType sourceType = null;
DatatypeDecl dtd = null;
Dictionary subst = new Dictionary();
if (s.Source.Type.IsDatatype) {
sourceType = (UserDefinedType)s.Source.Type;
dtd = cce.NonNull((DatatypeDecl)sourceType.ResolvedClass);
}
Dictionary ctors;
if (dtd == null) {
Error(s.Source, "the type of the match source expression must be a datatype (instead found {0})", s.Source.Type);
ctors = null;
} else {
Contract.Assert(sourceType != null); // dtd and sourceType are set together above
ctors = datatypeCtors[dtd];
Contract.Assert(ctors != null); // dtd should have been inserted into datatypeCtors during a previous resolution stage
// build the type-parameter substitution map for this use of the datatype
for (int i = 0; i < dtd.TypeArgs.Count; i++) {
subst.Add(dtd.TypeArgs[i], sourceType.TypeArgs[i]);
}
}
s.IsGhost = bodyIsSpecOnly;
Dictionary memberNamesUsed = new Dictionary(); // this is really a set
foreach (MatchCaseStmt mc in s.Cases) {
DatatypeCtor ctor = null;
if (ctors != null) {
Contract.Assert(dtd != null);
if (!ctors.TryGetValue(mc.Id, out ctor)) {
Error(mc.tok, "member {0} does not exist in datatype {1}", mc.Id, dtd.Name);
} else {
Contract.Assert(ctor != null); // follows from postcondition of TryGetValue
mc.Ctor = ctor;
if (ctor.Formals.Count != mc.Arguments.Count) {
Error(mc.tok, "member {0} has wrong number of formals (found {1}, expected {2})", mc.Id, mc.Arguments.Count, ctor.Formals.Count);
}
if (memberNamesUsed.ContainsKey(mc.Id)) {
Error(mc.tok, "member {0} appears in more than one case", mc.Id);
} else {
memberNamesUsed.Add(mc.Id, null); // add mc.Id to the set of names used
}
}
}
scope.PushMarker();
int i = 0;
foreach (BoundVar v in mc.Arguments) {
if (!scope.Push(v.Name, v)) {
Error(v, "Duplicate parameter name: {0}", v.Name);
}
ResolveType(v.tok, v.Type);
if (ctor != null && i < ctor.Formals.Count) {
Formal formal = ctor.Formals[i];
Type st = SubstType(formal.Type, subst);
if (!UnifyTypes(v.Type, st)) {
Error(stmt, "the declared type of the formal ({0}) does not agree with the corresponding type in the constructor's signature ({1})", v.Type, st);
}
v.IsGhost = formal.IsGhost;
}
i++;
}
foreach (Statement ss in mc.Body) {
ResolveStatement(ss, bodyIsSpecOnly, method);
}
scope.PopMarker();
}
if (dtd != null && memberNamesUsed.Count != dtd.Ctors.Count) {
// We could complain about the syntactic omission of constructors:
// Error(stmt, "match statement does not cover all constructors");
// but instead we let the verifier do a semantic check.
// So, for now, record the missing constructors:
foreach (var ctr in dtd.Ctors) {
if (!memberNamesUsed.ContainsKey(ctr.Name)) {
s.MissingCases.Add(ctr);
}
}
Contract.Assert(memberNamesUsed.Count + s.MissingCases.Count == dtd.Ctors.Count);
}
} else {
Contract.Assert(false); throw new cce.UnreachableException();
}
}
private void ResolveUpdateStmt(UpdateStmt s, bool specContextOnly, Method method)
{
int prevErrorCount = ErrorCount;
// First, resolve all LHS's and expression-looking RHS's.
SeqSelectExpr arrayRangeLhs = null;
foreach (var lhs in s.Lhss) {
if (lhs is SeqSelectExpr) {
var sse = (SeqSelectExpr)lhs;
ResolveSeqSelectExpr(sse, true, true);
if (arrayRangeLhs == null && !sse.SelectOne) {
arrayRangeLhs = sse;
}
}
else {
ResolveExpression(lhs, true);
}
}
IToken firstEffectfulRhs = null;
CallRhs callRhs = null;
// Resolve RHSs
foreach (var rhs in s.Rhss) {
bool isEffectful;
if (rhs is TypeRhs) {
var tr = (TypeRhs)rhs;
ResolveTypeRhs(tr, s, specContextOnly, method);
isEffectful = tr.InitCall != null;
} else if (rhs is HavocRhs) {
isEffectful = false;
} else {
var er = (ExprRhs)rhs;
if (er.Expr is IdentifierSequence) {
var cRhs = ResolveIdentifierSequence((IdentifierSequence)er.Expr, true, true);
isEffectful = cRhs != null;
callRhs = callRhs ?? cRhs;
} else if (er.Expr is FunctionCallExpr) {
var cRhs = ResolveFunctionCallExpr((FunctionCallExpr)er.Expr, true, true);
isEffectful = cRhs != null;
callRhs = callRhs ?? cRhs;
} else {
ResolveExpression(er.Expr, true);
isEffectful = false;
}
}
if (isEffectful && firstEffectfulRhs == null) {
firstEffectfulRhs = rhs.Tok;
}
}
// check for duplicate identifiers on the left (full duplication checking for references and the like is done during verification)
var lhsNameSet = new Dictionary();
foreach (var lhs in s.Lhss) {
var ie = lhs.Resolved as IdentifierExpr;
if (ie != null) {
if (lhsNameSet.ContainsKey(ie.Name)) {
Error(s, "Duplicate variable in left-hand side of {1} statement: {0}", ie.Name, callRhs != null ? "call" : "assignment");
} else {
lhsNameSet.Add(ie.Name, null);
}
}
}
// figure out what kind of UpdateStmt this is
if (firstEffectfulRhs == null) {
if (s.Lhss.Count == 0) {
Contract.Assert(s.Rhss.Count == 1); // guaranteed by the parser
Error(s, "expected method call, found expression");
}
else if (s.Lhss.Count != s.Rhss.Count) {
Error(s, "the number of left-hand sides ({0}) and right-hand sides ({1}) must match for a multi-assignment", s.Lhss.Count, s.Rhss.Count);
}
else if (arrayRangeLhs != null && s.Lhss.Count != 1) {
Error(arrayRangeLhs, "array-range may not be used as LHS of multi-assignment; use separate assignment statements for each array-range assignment");
}
else if (ErrorCount == prevErrorCount) {
// add the statements here in a sequence, but don't use that sequence later for translation (instead, should translated properly as multi-assignment)
for (int i = 0; i < s.Lhss.Count; i++) {
var a = new AssignStmt(s.Tok, s.Lhss[i].Resolved, s.Rhss[i]);
s.ResolvedStatements.Add(a);
}
}
}
else {
if (s.CanMutateKnownState) {
if (1 < s.Rhss.Count)
Error(firstEffectfulRhs, "cannot have effectful parameter in multi-return statement.");
else { // it might be ok, if it is a TypeExpr
Contract.Assert(s.Rhss.Count == 1);
if (callRhs != null) {
Error(callRhs.Tok, "cannot have method call in return statement.");
}
else {
// we have a TypeExpr
Contract.Assert(s.Rhss[0] is TypeRhs);
var tr = (TypeRhs)s.Rhss[0];
Contract.Assert(tr.InitCall != null); // there were effects, so this must have been a call.
if (tr.CanAffectPreviouslyKnownExpressions) {
Error(tr.Tok, "can only have initialization methods which modify at most 'this'.");
}
}
}
}
else {
// if there was an effectful RHS, that must be the only RHS
if (s.Rhss.Count != 1) {
Error(firstEffectfulRhs, "an update statement is allowed an effectful RHS only if there is just one RHS");
}
else if (arrayRangeLhs != null) {
Error(arrayRangeLhs, "Assignment to range of array elements must have a simple expression RHS; try using a temporary local variable");
}
else if (callRhs == null) {
// must be a single TypeRhs
if (s.Lhss.Count != 1) {
Contract.Assert(2 <= s.Lhss.Count); // the parser allows 0 Lhss only if the whole statement looks like an expression (not a TypeRhs)
Error(s.Lhss[1].tok, "the number of left-hand sides ({0}) and right-hand sides ({1}) must match for a multi-assignment", s.Lhss.Count, s.Rhss.Count);
}
else if (ErrorCount == prevErrorCount) {
var a = new AssignStmt(s.Tok, s.Lhss[0].Resolved, s.Rhss[0]);
s.ResolvedStatements.Add(a);
}
}
else {
// a call statement
if (ErrorCount == prevErrorCount) {
var resolvedLhss = new List();
foreach (var ll in s.Lhss) {
resolvedLhss.Add(ll.Resolved);
}
var a = new CallStmt(callRhs.Tok, resolvedLhss, callRhs.Receiver, callRhs.MethodName, callRhs.Args);
s.ResolvedStatements.Add(a);
}
}
}
}
foreach (var a in s.ResolvedStatements) {
ResolveStatement(a, specContextOnly, method);
}
}
bool ResolveAlternatives(List alternatives, bool specContextOnly, AlternativeLoopStmt loopToCatchBreaks, Method method) {
Contract.Requires(alternatives != null);
Contract.Requires(method != null);
bool isGhost = specContextOnly;
// first, resolve the guards, which tells us whether or not the entire statement is a ghost statement
foreach (var alternative in alternatives) {
int prevErrorCount = ErrorCount;
ResolveExpression(alternative.Guard, true);
Contract.Assert(alternative.Guard.Type != null); // follows from postcondition of ResolveExpression
bool successfullyResolved = ErrorCount == prevErrorCount;
if (!UnifyTypes(alternative.Guard.Type, Type.Bool)) {
Error(alternative.Guard, "condition is expected to be of type {0}, but is {1}", Type.Bool, alternative.Guard.Type);
}
if (!specContextOnly && successfullyResolved) {
isGhost = isGhost || UsesSpecFeatures(alternative.Guard);
}
}
if (loopToCatchBreaks != null) {
loopStack.Add(loopToCatchBreaks); // push
if (loopToCatchBreaks.Labels == null) { // otherwise, "loopToCatchBreak" is already in "inSpecOnlyContext" map
inSpecOnlyContext.Add(loopToCatchBreaks, specContextOnly);
}
}
foreach (var alternative in alternatives) {
scope.PushMarker();
foreach (Statement ss in alternative.Body) {
ResolveStatement(ss, isGhost, method);
}
scope.PopMarker();
}
if (loopToCatchBreaks != null) {
loopStack.RemoveAt(loopStack.Count - 1); // pop
}
return isGhost;
}
///
/// Resolves the given call statement.
/// Assumes all LHSs have already been resolved (and checked for mutability).
///
void ResolveCallStmt(CallStmt s, bool specContextOnly, Method method, Type receiverType) {
Contract.Requires(s != null);
Contract.Requires(method != null);
bool isInitCall = receiverType != null;
// resolve receiver, unless told otherwise
if (receiverType == null) {
ResolveReceiver(s.Receiver, true);
Contract.Assert(s.Receiver.Type != null); // follows from postcondition of ResolveExpression
receiverType = s.Receiver.Type;
}
// resolve the method name
NonProxyType nptype;
MemberDecl member = ResolveMember(s.Tok, receiverType, s.MethodName, out nptype);
Method callee = null;
if (member == null) {
// error has already been reported by ResolveMember
} else if (!(member is Method)) {
Error(s, "member {0} in type {1} does not refer to a method", s.MethodName, nptype);
} else {
callee = (Method)member;
s.Method = callee;
if (!isInitCall && callee is Constructor) {
Error(s, "a constructor is only allowed to be called when an object is being allocated");
}
s.IsGhost = callee.IsGhost;
if (specContextOnly && !callee.IsGhost) {
Error(s, "only ghost methods can be called from this context");
}
}
// resolve left-hand sides
foreach (var lhs in s.Lhs) {
Contract.Assume(lhs.Type != null); // a sanity check that LHSs have already been resolved
}
// resolve arguments
if (!s.IsGhost && s.Receiver.WasResolved()) {
CheckIsNonGhost(s.Receiver);
}
int j = 0;
foreach (Expression e in s.Args) {
bool allowGhost = s.IsGhost || callee == null || callee.Ins.Count <= j || callee.Ins[j].IsGhost;
ResolveExpression(e, true);
if (!allowGhost) {
CheckIsNonGhost(e);
}
j++;
}
if (callee == null) {
// error has been reported above
} else if (callee.Ins.Count != s.Args.Count) {
Error(s, "wrong number of method arguments (got {0}, expected {1})", s.Args.Count, callee.Ins.Count);
} else if (callee.Outs.Count != s.Lhs.Count) {
if (isInitCall) {
Error(s, "a method called as an initialization method must not have any result arguments");
} else {
Error(s, "wrong number of method result arguments (got {0}, expected {1})", s.Lhs.Count, callee.Outs.Count);
}
} else {
Contract.Assert(nptype != null); // follows from postcondition of ResolveMember above
if (isInitCall) {
if (callee.IsStatic) {
Error(s.Tok, "a method called as an initialization method must not be 'static'");
}
} else if (!callee.IsStatic) {
if (!scope.AllowInstance && s.Receiver is ThisExpr) {
// The call really needs an instance, but that instance is given as 'this', which is not
// available in this context. For more details, see comment in the resolution of a
// FunctionCallExpr.
Error(s.Receiver, "'this' is not allowed in a 'static' context");
} else if (s.Receiver is StaticReceiverExpr) {
Error(s.Receiver, "call to instance method requires an instance");
}
}
#if !NO_WORK_TO_BE_DONE
UserDefinedType ctype = (UserDefinedType)nptype; // TODO: get rid of this statement, make this code handle any non-proxy type
#endif
// build the type substitution map
Dictionary subst = new Dictionary();
for (int i = 0; i < ctype.TypeArgs.Count; i++) {
subst.Add(cce.NonNull(ctype.ResolvedClass).TypeArgs[i], ctype.TypeArgs[i]);
}
foreach (TypeParameter p in callee.TypeArgs) {
subst.Add(p, new ParamTypeProxy(p));
}
// type check the arguments
for (int i = 0; i < callee.Ins.Count; i++) {
Type st = SubstType(callee.Ins[i].Type, subst);
if (!UnifyTypes(cce.NonNull(s.Args[i].Type), st)) {
Error(s, "incorrect type of method in-parameter {0} (expected {1}, got {2})", i, st, s.Args[i].Type);
}
}
for (int i = 0; i < callee.Outs.Count; i++) {
Type st = SubstType(callee.Outs[i].Type, subst);
var lhs = s.Lhs[i];
if (!UnifyTypes(cce.NonNull(lhs.Type), st)) {
Error(s, "incorrect type of method out-parameter {0} (expected {1}, got {2})", i, st, lhs.Type);
} else {
var resolvedLhs = lhs.Resolved;
if (!specContextOnly && (s.IsGhost || callee.Outs[i].IsGhost)) {
// LHS must denote a ghost
if (resolvedLhs is IdentifierExpr) {
var ll = (IdentifierExpr)resolvedLhs;
if (!ll.Var.IsGhost) {
if (ll is AutoGhostIdentifierExpr && ll.Var is VarDecl) {
// the variable was actually declared in this statement, so auto-declare it as ghost
((VarDecl)ll.Var).MakeGhost();
} else {
Error(s, "actual out-parameter {0} is required to be a ghost variable", i);
}
}
} else if (resolvedLhs is FieldSelectExpr) {
var ll = (FieldSelectExpr)resolvedLhs;
if (!ll.Field.IsGhost) {
Error(s, "actual out-parameter {0} is required to be a ghost field", i);
}
} else {
// this is an array update, and arrays are always non-ghost
Error(s, "actual out-parameter {0} is required to be a ghost variable", i);
}
}
// LHS must denote a mutable field.
if (resolvedLhs is IdentifierExpr) {
var ll = (IdentifierExpr)resolvedLhs;
if (!ll.Var.IsMutable) {
Error(resolvedLhs, "LHS of assignment must denote a mutable variable");
}
} else if (resolvedLhs is FieldSelectExpr) {
var ll = (FieldSelectExpr)resolvedLhs;
if (!ll.Field.IsMutable) {
Error(resolvedLhs, "LHS of assignment must denote a mutable field");
}
}
}
}
// Resolution termination check
if (method.EnclosingClass != null && callee.EnclosingClass != null) {
ModuleDecl callerModule = method.EnclosingClass.Module;
ModuleDecl calleeModule = callee.EnclosingClass.Module;
if (callerModule == calleeModule) {
// intra-module call; this is allowed; add edge in module's call graph
callerModule.CallGraph.AddEdge(method, callee);
} else if (calleeModule.IsDefaultModule) {
// all is fine: everything implicitly imports the default module
} else if (importGraph.Reaches(callerModule, calleeModule)) {
// all is fine: the callee is downstream of the caller
} else {
Error(s, "inter-module calls must follow the module import relation (so module {0} must transitively import {1})", callerModule.Name, calleeModule.Name);
}
}
}
}
void ResolveBlockStatement(BlockStmt blockStmt, bool specContextOnly, Method method)
{
Contract.Requires(blockStmt != null);
Contract.Requires(method != null);
foreach (Statement ss in blockStmt.Body) {
labeledStatements.PushMarker();
// push labels
for (var lnode = ss.Labels; lnode != null; lnode = lnode.Next) {
Contract.Assert(lnode.Label != null); // LabelNode's with .Label==null are added only during resolution of the break statements with 'stmt' as their target, which hasn't happened yet
var prev = labeledStatements.Find(lnode.Label);
if (prev == ss) {
Error(lnode.Tok, "duplicate label");
} else if (prev != null) {
Error(lnode.Tok, "label shadows an enclosing label");
} else {
bool b = labeledStatements.Push(lnode.Label, ss);
Contract.Assert(b); // since we just checked for duplicates, we expect the Push to succeed
if (lnode == ss.Labels) { // add it only once
inSpecOnlyContext.Add(ss, specContextOnly);
}
}
}
ResolveStatement(ss, specContextOnly, method);
labeledStatements.PopMarker();
}
}
///
/// This method performs some additional checks on the body "stmt" of a parallel statement
///
public void CheckParallelBodyRestrictions(Statement stmt, bool allowHeapUpdates) {
Contract.Requires(stmt != null);
if (stmt is PredicateStmt) {
// cool
} else if (stmt is PrintStmt) {
Error(stmt, "print statement is not allowed inside a parallel statement");
} else if (stmt is BreakStmt) {
// this case can be checked already in the first pass through the parallel body, by doing so from an empty set of labeled statements and resetting the loop-stack
} else if (stmt is ReturnStmt) {
Error(stmt, "return statement is not allowed inside a parallel statement");
} else if (stmt is ConcreteSyntaxStatement) {
var s = (ConcreteSyntaxStatement)stmt;
foreach (var ss in s.ResolvedStatements) {
CheckParallelBodyRestrictions(ss, allowHeapUpdates);
}
} else if (stmt is AssignStmt) {
var s = (AssignStmt)stmt;
var idExpr = s.Lhs.Resolved as IdentifierExpr;
if (idExpr != null) {
if (scope.ContainsDecl(idExpr.Var)) {
Error(stmt, "body of parallel statement is attempting to update a variable declared outside the parallel statement");
}
} else if (!allowHeapUpdates) {
Error(stmt, "the body of the enclosing parallel statement may not update heap locations");
}
var rhs = s.Rhs; // ExprRhs and HavocRhs are fine, but TypeRhs is not
if (rhs is TypeRhs) {
Error(rhs.Tok, "new allocation not supported in parallel statements");
} else if (rhs is ExprRhs) {
var r = ((ExprRhs)rhs).Expr.Resolved;
if (r is UnaryExpr && ((UnaryExpr)r).Op == UnaryExpr.Opcode.SetChoose) {
Error(r, "set choose operator not supported inside parallel statement");
}
}
} else if (stmt is VarDecl) {
// cool
} else if (stmt is CallStmt) {
var s = (CallStmt)stmt;
foreach (var lhs in s.Lhs) {
var idExpr = lhs as IdentifierExpr;
if (idExpr != null) {
if (scope.ContainsDecl(idExpr.Var)) {
Error(stmt, "body of parallel statement is attempting to update a variable declared outside the parallel statement");
}
} else {
Error(stmt, "the body of the enclosing parallel statement may not update heap locations");
}
}
if (s.Method.Mod.Count != 0) {
Error(s, "in the body of a parallel statement, every method called must have an empty modifies list");
}
} else if (stmt is BlockStmt) {
var s = (BlockStmt)stmt;
scope.PushMarker();
foreach (var ss in s.Body) {
CheckParallelBodyRestrictions(ss, allowHeapUpdates);
}
scope.PopMarker();
} else if (stmt is IfStmt) {
var s = (IfStmt)stmt;
CheckParallelBodyRestrictions(s.Thn, allowHeapUpdates);
if (s.Els != null) {
CheckParallelBodyRestrictions(s.Els, allowHeapUpdates);
}
} else if (stmt is AlternativeStmt) {
var s = (AlternativeStmt)stmt;
foreach (var alt in s.Alternatives) {
foreach (var ss in alt.Body) {
CheckParallelBodyRestrictions(ss, allowHeapUpdates);
}
}
} else if (stmt is WhileStmt) {
WhileStmt s = (WhileStmt)stmt;
CheckParallelBodyRestrictions(s.Body, allowHeapUpdates);
} else if (stmt is AlternativeLoopStmt) {
var s = (AlternativeLoopStmt)stmt;
foreach (var alt in s.Alternatives) {
foreach (var ss in alt.Body) {
CheckParallelBodyRestrictions(ss, allowHeapUpdates);
}
}
} else if (stmt is ParallelStmt) {
var s = (ParallelStmt)stmt;
switch (s.Kind) {
case ParallelStmt.ParBodyKind.Assign:
Error(stmt, "a parallel statement with heap updates is not allowed inside the body of another parallel statement");
break;
case ParallelStmt.ParBodyKind.Call:
case ParallelStmt.ParBodyKind.Proof:
// these are fine, since they don't update any non-local state
break;
default:
Contract.Assert(false); // unexpected kind
break;
}
} else if (stmt is MatchStmt) {
var s = (MatchStmt)stmt;
foreach (var kase in s.Cases) {
foreach (var ss in kase.Body) {
CheckParallelBodyRestrictions(ss, allowHeapUpdates);
}
}
} else {
Contract.Assert(false); throw new cce.UnreachableException();
}
}
Type ResolveTypeRhs(TypeRhs rr, Statement stmt, bool specContextOnly, Method method) {
Contract.Requires(rr != null);
Contract.Requires(stmt != null);
Contract.Requires(method != null);
Contract.Ensures(Contract.Result() != null);
if (rr.Type == null) {
ResolveType(stmt.Tok, rr.EType);
if (rr.ArrayDimensions == null) {
if (!rr.EType.IsRefType) {
Error(stmt, "new can be applied only to reference types (got {0})", rr.EType);
} else {
bool callsConstructor = false;
if (rr.InitCall != null) {
ResolveCallStmt(rr.InitCall, specContextOnly, method, rr.EType);
if (rr.InitCall.Method is Constructor) {
callsConstructor = true;
}
}
if (!callsConstructor && rr.EType is UserDefinedType) {
var udt = (UserDefinedType)rr.EType;
var cl = (ClassDecl)udt.ResolvedClass; // cast is guarantted by the call to rr.EType.IsRefType above, together with the "rr.EType is UserDefinedType" test
if (cl.HasConstructor) {
Error(stmt, "when allocating an object of type '{0}', one of its constructor methods must be called", cl.Name);
}
}
}
rr.Type = rr.EType;
} else {
int i = 0;
if (rr.EType.IsSubrangeType) {
Error(stmt, "sorry, cannot instantiate 'array' type with a subrange type");
}
foreach (Expression dim in rr.ArrayDimensions) {
Contract.Assert(dim != null);
ResolveExpression(dim, true);
if (!UnifyTypes(dim.Type, Type.Int)) {
Error(stmt, "new must use an integer expression for the array size (got {0} for index {1})", dim.Type, i);
}
i++;
}
rr.Type = builtIns.ArrayType(rr.ArrayDimensions.Count, rr.EType);
}
}
return rr.Type;
}
MemberDecl ResolveMember(IToken tok, Type receiverType, string memberName, out NonProxyType nptype)
{
Contract.Requires(tok != null);
Contract.Requires(receiverType != null);
Contract.Requires(memberName != null);
Contract.Ensures(Contract.Result() == null || Contract.ValueAtReturn(out nptype) != null);
nptype = null; // prepare for the worst
receiverType = receiverType.Normalize();
if (receiverType is TypeProxy) {
Error(tok, "type of the receiver is not fully determined at this program point", receiverType);
return null;
}
Contract.Assert(receiverType is NonProxyType); // there are only two kinds of types: proxies and non-proxies
UserDefinedType ctype = UserDefinedType.DenotesClass(receiverType);
if (ctype != null) {
ClassDecl cd = (ClassDecl)ctype.ResolvedClass; // correctness of cast follows from postcondition of DenotesClass
Contract.Assert(ctype.TypeArgs.Count == cd.TypeArgs.Count); // follows from the fact that ctype was resolved
MemberDecl member;
if (!classMembers[cd].TryGetValue(memberName, out member)) {
Error(tok, "member {0} does not exist in class {1}", memberName, ctype.Name);
return null;
} else {
nptype = ctype;
return member;
}
}
DatatypeDecl dtd = receiverType.AsDatatype;
if (dtd != null) {
MemberDecl member;
if (!datatypeMembers[dtd].TryGetValue(memberName, out member)) {
Error(tok, "member {0} does not exist in datatype {1}", memberName, dtd.Name);
return null;
} else {
nptype = (UserDefinedType)receiverType;
return member;
}
}
Error(tok, "type {0} does not have a member {1}", receiverType, memberName);
return null;
}
public static Type SubstType(Type type, Dictionary/*!*/ subst) {
Contract.Requires(type != null);
Contract.Requires(cce.NonNullDictionaryAndValues(subst));
Contract.Ensures(Contract.Result() != null);
if (type is BasicType) {
return type;
} else if (type is CollectionType) {
CollectionType t = (CollectionType)type;
Type arg = SubstType(t.Arg, subst);
if (arg == t.Arg) {
return type;
} else if (type is SetType) {
return new SetType(arg);
} else if (type is MultiSetType) {
return new MultiSetType(arg);
} else if (type is SeqType) {
return new SeqType(arg);
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected collection type
}
} else if (type is UserDefinedType) {
UserDefinedType t = (UserDefinedType)type;
if (t.ResolvedParam != null) {
Contract.Assert(t.TypeArgs.Count == 0);
Type s;
if (subst.TryGetValue(t.ResolvedParam, out s)) {
return cce.NonNull(s);
} else {
return type;
}
} else if (t.ResolvedClass != null) {
List newArgs = null; // allocate it lazily
for (int i = 0; i < t.TypeArgs.Count; i++) {
Type p = t.TypeArgs[i];
Type s = SubstType(p, subst);
if (s != p && newArgs == null) {
// lazily construct newArgs
newArgs = new List();
for (int j = 0; j < i; j++) {
newArgs.Add(t.TypeArgs[j]);
}
}
if (newArgs != null) {
newArgs.Add(s);
}
}
if (newArgs == null) {
// there were no substitutions
return type;
} else {
return new UserDefinedType(t.tok, t.Name, t.ResolvedClass, newArgs);
}
} else {
// there's neither a resolved param nor a resolved class, which means the UserDefinedType wasn't
// properly resolved; just return it
return type;
}
} else if (type is TypeProxy) {
TypeProxy t = (TypeProxy)type;
if (t.T == null) {
return type;
} else {
// bypass the proxy
return SubstType(t.T, subst);
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected type
}
}
public static UserDefinedType GetThisType(IToken tok, ClassDecl cl) {
Contract.Requires(tok != null);
Contract.Requires(cl != null);
Contract.Ensures(Contract.Result() != null);
List args = new List();
foreach (TypeParameter tp in cl.TypeArgs) {
args.Add(new UserDefinedType(tok, tp.Name, tp));
}
return new UserDefinedType(tok, cl.Name, cl, args);
}
///
/// Requires "member" to be declared in a class.
///
public static UserDefinedType GetReceiverType(IToken tok, MemberDecl member) {
Contract.Requires(tok != null);
Contract.Requires(member != null);
Contract.Ensures(Contract.Result() != null);
return GetThisType(tok, (ClassDecl)member.EnclosingClass);
}
///
/// "twoState" implies that "old" and "fresh" expressions are allowed
///
void ResolveExpression(Expression expr, bool twoState) {
ResolveExpression(expr, twoState, null);
}
///
/// "matchVarContext" says which variables are allowed to be used as the source expression in a "match" expression;
/// if null, no "match" expression will be allowed.
///
void ResolveExpression(Expression expr, bool twoState, List matchVarContext) {
Contract.Requires(expr != null);
Contract.Requires(currentClass != null);
Contract.Ensures(expr.Type != null);
if (expr.Type != null) {
// expression has already been resovled
return;
}
// The following cases will resolve the subexpressions and will attempt to assign a type of expr. However, if errors occur
// and it cannot be determined what the type of expr is, then it is fine to leave expr.Type as null. In that case, the end
// of this method will assign proxy type to the expression, which reduces the number of error messages that are produced
// while type checking the rest of the program.
if (expr is ParensExpression) {
var e = (ParensExpression)expr;
ResolveExpression(e.E, twoState, matchVarContext); // allow "match" expressions inside e.E if the parenthetic expression had been allowed to be a "match" expression
e.ResolvedExpression = e.E;
e.Type = e.E.Type;
} else if (expr is ChainingExpression) {
var e = (ChainingExpression)expr;
ResolveExpression(e.E, twoState);
e.ResolvedExpression = e.E;
e.Type = e.E.Type;
} else if (expr is IdentifierSequence) {
var e = (IdentifierSequence)expr;
ResolveIdentifierSequence(e, twoState, false);
} else if (expr is LiteralExpr) {
LiteralExpr e = (LiteralExpr)expr;
if (e.Value == null) {
e.Type = new ObjectTypeProxy();
} else if (e.Value is BigInteger) {
e.Type = Type.Int;
} else if (e.Value is bool) {
e.Type = Type.Bool;
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected literal type
}
} else if (expr is ThisExpr) {
if (!scope.AllowInstance) {
Error(expr, "'this' is not allowed in a 'static' context");
}
expr.Type = GetThisType(expr.tok, currentClass); // do this regardless of scope.AllowInstance, for better error reporting
} else if (expr is IdentifierExpr) {
IdentifierExpr e = (IdentifierExpr)expr;
e.Var = scope.Find(e.Name);
if (e.Var == null) {
Error(expr, "Identifier does not denote a local variable, parameter, or bound variable: {0}", e.Name);
} else {
expr.Type = e.Var.Type;
}
} else if (expr is DatatypeValue) {
DatatypeValue dtv = (DatatypeValue)expr;
TopLevelDecl d;
if (!classes.TryGetValue(dtv.DatatypeName, out d)) {
Error(expr.tok, "Undeclared datatype: {0}", dtv.DatatypeName);
} else if (!(d is DatatypeDecl)) {
Error(expr.tok, "Expected datatype, found class: {0}", dtv.DatatypeName);
} else {
// this resolution is a little special, in that the syntax shows only the base name, not its instantiation (which is inferred)
DatatypeDecl dt = (DatatypeDecl)d;
List gt = new List(dt.TypeArgs.Count);
Dictionary subst = new Dictionary();
for (int i = 0; i < dt.TypeArgs.Count; i++) {
Type t = new InferredTypeProxy();
gt.Add(t);
dtv.InferredTypeArgs.Add(t);
subst.Add(dt.TypeArgs[i], t);
}
expr.Type = new UserDefinedType(dtv.tok, dtv.DatatypeName, gt);
ResolveType(expr.tok, expr.Type);
DatatypeCtor ctor;
if (!datatypeCtors[dt].TryGetValue(dtv.MemberName, out ctor)) {
Error(expr.tok, "undeclared constructor {0} in datatype {1}", dtv.MemberName, dtv.DatatypeName);
} else {
Contract.Assert(ctor != null); // follows from postcondition of TryGetValue
dtv.Ctor = ctor;
if (ctor.Formals.Count != dtv.Arguments.Count) {
Error(expr.tok, "wrong number of arguments to datatype constructor {0} (found {1}, expected {2})", dtv.DatatypeName, dtv.Arguments.Count, ctor.Formals.Count);
}
}
int j = 0;
foreach (Expression arg in dtv.Arguments) {
Formal formal = ctor != null && j < ctor.Formals.Count ? ctor.Formals[j] : null;
ResolveExpression(arg, twoState);
Contract.Assert(arg.Type != null); // follows from postcondition of ResolveExpression
if (formal != null) {
Type st = SubstType(formal.Type, subst);
if (!UnifyTypes(arg.Type, st)) {
Error(arg.tok, "incorrect type of datatype constructor argument (found {0}, expected {1})", arg.Type, st);
}
}
j++;
}
}
} else if (expr is DisplayExpression) {
DisplayExpression e = (DisplayExpression)expr;
Type elementType = new InferredTypeProxy();
foreach (Expression ee in e.Elements) {
ResolveExpression(ee, twoState);
Contract.Assert(ee.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(elementType, ee.Type)) {
Error(ee, "All elements of display must be of the same type (got {0}, but type of previous elements is {1})", ee.Type, elementType);
}
}
if (expr is SetDisplayExpr) {
expr.Type = new SetType(elementType);
} else if (expr is MultiSetDisplayExpr) {
expr.Type = new MultiSetType(elementType);
} else {
expr.Type = new SeqType(elementType);
}
} else if (expr is FieldSelectExpr) {
var e = (FieldSelectExpr)expr;
ResolveExpression(e.Obj, twoState);
Contract.Assert(e.Obj.Type != null); // follows from postcondition of ResolveExpression
NonProxyType nptype;
MemberDecl member = ResolveMember(expr.tok, e.Obj.Type, e.FieldName, out nptype);
#if !NO_WORK_TO_BE_DONE
UserDefinedType ctype = (UserDefinedType)nptype;
#endif
if (member == null) {
// error has already been reported by ResolveMember
} else if (!(member is Field)) {
Error(expr, "member {0} in type {1} does not refer to a field", e.FieldName, cce.NonNull(ctype).Name);
} else {
Contract.Assert(ctype != null && ctype.ResolvedClass != null); // follows from postcondition of ResolveMember
e.Field = (Field)member;
if (e.Obj is StaticReceiverExpr) {
Error(expr, "a field must be selected via an object, not just a class name");
}
// build the type substitution map
Dictionary subst = new Dictionary();
for (int i = 0; i < ctype.TypeArgs.Count; i++) {
subst.Add(ctype.ResolvedClass.TypeArgs[i], ctype.TypeArgs[i]);
}
e.Type = SubstType(e.Field.Type, subst);
}
} else if (expr is SeqSelectExpr) {
SeqSelectExpr e = (SeqSelectExpr)expr;
ResolveSeqSelectExpr(e, twoState, true);
} else if (expr is MultiSelectExpr) {
MultiSelectExpr e = (MultiSelectExpr)expr;
ResolveExpression(e.Array, twoState);
Contract.Assert(e.Array.Type != null); // follows from postcondition of ResolveExpression
Type elementType = new InferredTypeProxy();
if (!UnifyTypes(e.Array.Type, builtIns.ArrayType(e.Indices.Count, elementType))) {
Error(e.Array, "array selection requires an array{0} (got {1})", e.Indices.Count, e.Array.Type);
}
int i = 0;
foreach (Expression idx in e.Indices) {
Contract.Assert(idx != null);
ResolveExpression(idx, twoState);
Contract.Assert(idx.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(idx.Type, Type.Int)) {
Error(idx, "array selection requires integer indices (got {0} for index {1})", idx.Type, i);
}
i++;
}
e.Type = elementType;
} else if (expr is SeqUpdateExpr) {
SeqUpdateExpr e = (SeqUpdateExpr)expr;
bool seqErr = false;
ResolveExpression(e.Seq, twoState);
Contract.Assert(e.Seq.Type != null); // follows from postcondition of ResolveExpression
Type elementType = new InferredTypeProxy();
if (!UnifyTypes(e.Seq.Type, new SeqType(elementType))) {
Error(expr, "sequence update requires a sequence (got {0})", e.Seq.Type);
seqErr = true;
}
ResolveExpression(e.Index, twoState);
Contract.Assert(e.Index.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Index.Type, Type.Int)) {
Error(e.Index, "sequence update requires integer index (got {0})", e.Index.Type);
}
ResolveExpression(e.Value, twoState);
Contract.Assert(e.Value.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Value.Type, elementType)) {
Error(e.Value, "sequence update requires the value to have the element type of the sequence (got {0})", e.Value.Type);
}
if (!seqErr) {
expr.Type = e.Seq.Type;
}
} else if (expr is FunctionCallExpr) {
FunctionCallExpr e = (FunctionCallExpr)expr;
ResolveFunctionCallExpr(e, twoState, false);
} else if (expr is OldExpr) {
OldExpr e = (OldExpr)expr;
if (!twoState) {
Error(expr, "old expressions are not allowed in this context");
}
ResolveExpression(e.E, twoState);
expr.Type = e.E.Type;
} else if (expr is MultiSetFormingExpr) {
MultiSetFormingExpr e = (MultiSetFormingExpr)expr;
ResolveExpression(e.E, twoState);
if (!UnifyTypes(e.E.Type, new SetType(new InferredTypeProxy())) && !UnifyTypes(e.E.Type, new SeqType(new InferredTypeProxy()))) {
Error(e.tok, "can only form a multiset from a seq or set.");
}
expr.Type = new MultiSetType(((CollectionType)e.E.Type).Arg);
} else if (expr is FreshExpr) {
FreshExpr e = (FreshExpr)expr;
if (!twoState) {
Error(expr, "fresh expressions are not allowed in this context");
}
ResolveExpression(e.E, twoState);
// the type of e.E must be either an object or a collection of objects
Type t = e.E.Type;
Contract.Assert(t != null); // follows from postcondition of ResolveExpression
if (t is CollectionType) {
t = ((CollectionType)t).Arg;
}
if (t is ObjectType) {
// fine
} else if (UserDefinedType.DenotesClass(t) != null) {
// fine
} else {
Error(expr, "the argument of a fresh expression must denote an object or a collection of objects (instead got {0})", e.E.Type);
}
expr.Type = Type.Bool;
} else if (expr is AllocatedExpr) {
AllocatedExpr e = (AllocatedExpr)expr;
ResolveExpression(e.E, twoState);
// e.E can be of any type
expr.Type = Type.Bool;
} else if (expr is UnaryExpr) {
UnaryExpr e = (UnaryExpr)expr;
ResolveExpression(e.E, twoState);
Contract.Assert(e.E.Type != null); // follows from postcondition of ResolveExpression
switch (e.Op) {
case UnaryExpr.Opcode.Not:
if (!UnifyTypes(e.E.Type, Type.Bool)) {
Error(expr, "logical negation expects a boolean argument (instead got {0})", e.E.Type);
}
expr.Type = Type.Bool;
break;
case UnaryExpr.Opcode.SetChoose:
var elType = new InferredTypeProxy();
if (!UnifyTypes(e.E.Type, new SetType(elType))) {
Error(expr, "choose operator expects a set argument (instead got {0})", e.E.Type);
}
expr.Type = elType;
break;
case UnaryExpr.Opcode.SeqLength:
if (!UnifyTypes(e.E.Type, new SeqType(new InferredTypeProxy()))) {
Error(expr, "length operator expects a sequence argument (instead got {0})", e.E.Type);
}
expr.Type = Type.Int;
break;
default:
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected unary operator
}
} else if (expr is BinaryExpr) {
BinaryExpr e = (BinaryExpr)expr;
ResolveExpression(e.E0, twoState);
Contract.Assert(e.E0.Type != null); // follows from postcondition of ResolveExpression
ResolveExpression(e.E1, twoState);
Contract.Assert(e.E1.Type != null); // follows from postcondition of ResolveExpression
switch (e.Op) {
case BinaryExpr.Opcode.Iff:
case BinaryExpr.Opcode.Imp:
case BinaryExpr.Opcode.And:
case BinaryExpr.Opcode.Or:
if (!UnifyTypes(e.E0.Type, Type.Bool)) {
Error(expr, "first argument to {0} must be of type bool (instead got {1})", BinaryExpr.OpcodeString(e.Op), e.E0.Type);
}
if (!UnifyTypes(e.E1.Type, Type.Bool)) {
Error(expr, "second argument to {0} must be of type bool (instead got {1})", BinaryExpr.OpcodeString(e.Op), e.E1.Type);
}
expr.Type = Type.Bool;
break;
case BinaryExpr.Opcode.Eq:
case BinaryExpr.Opcode.Neq:
if (!UnifyTypes(e.E0.Type, e.E1.Type)) {
Error(expr, "arguments must have the same type (got {0} and {1})", e.E0.Type, e.E1.Type);
}
expr.Type = Type.Bool;
break;
case BinaryExpr.Opcode.Disjoint:
// TODO: the error messages are backwards from what (ideally) they should be. this is necessary because UnifyTypes can't backtrack.
if (!UnifyTypes(e.E0.Type, e.E1.Type)) {
Error(expr, "arguments must have the same type (got {0} and {1})", e.E0.Type, e.E1.Type);
}
if (!UnifyTypes(e.E0.Type, new SetType(new InferredTypeProxy())) && !UnifyTypes(e.E0.Type, new MultiSetType(new InferredTypeProxy()))) {
Error(expr, "arguments must be of a [multi]set type (got {0})", e.E0.Type);
}
expr.Type = Type.Bool;
break;
case BinaryExpr.Opcode.Lt:
case BinaryExpr.Opcode.Le:
case BinaryExpr.Opcode.Add:
{
if (e.Op == BinaryExpr.Opcode.Lt && e.E0.Type.IsDatatype) {
if (!UnifyTypes(e.E1.Type, new DatatypeProxy())) {
Error(expr, "arguments to rank comparison must be datatypes (instead of {0})", e.E1.Type);
}
expr.Type = Type.Bool;
} else if (e.Op == BinaryExpr.Opcode.Lt && e.E1.Type.IsDatatype) {
if (!UnifyTypes(e.E0.Type, new DatatypeProxy())) {
Error(expr, "arguments to rank comparison must be datatypes (instead of {0})", e.E0.Type);
}
expr.Type = Type.Bool;
} else {
bool err = false;
if (!UnifyTypes(e.E0.Type, new OperationTypeProxy(true))) {
Error(expr, "arguments to {0} must be int or a collection type (instead got {1})", BinaryExpr.OpcodeString(e.Op), e.E0.Type);
err = true;
}
if (!UnifyTypes(e.E1.Type, e.E0.Type)) {
Error(expr, "arguments to {0} must have the same type (got {1} and {2})", BinaryExpr.OpcodeString(e.Op), e.E0.Type, e.E1.Type);
err = true;
}
if (e.Op != BinaryExpr.Opcode.Add) {
expr.Type = Type.Bool;
} else if (!err) {
expr.Type = e.E0.Type;
}
}
}
break;
case BinaryExpr.Opcode.Sub:
case BinaryExpr.Opcode.Mul:
case BinaryExpr.Opcode.Gt:
case BinaryExpr.Opcode.Ge:
{
if (e.Op == BinaryExpr.Opcode.Gt && e.E0.Type.IsDatatype) {
if (!UnifyTypes(e.E1.Type, new DatatypeProxy())) {
Error(expr, "arguments to rank comparison must be datatypes (instead of {0})", e.E1.Type);
}
expr.Type = Type.Bool;
} else {
bool err = false;
if (!UnifyTypes(e.E0.Type, new OperationTypeProxy(false))) {
Error(expr, "arguments to {0} must be int or a set (instead got {1})", BinaryExpr.OpcodeString(e.Op), e.E0.Type);
err = true;
}
if (!UnifyTypes(e.E1.Type, e.E0.Type)) {
Error(expr, "arguments to {0} must have the same type (got {1} and {2})", BinaryExpr.OpcodeString(e.Op), e.E0.Type, e.E1.Type);
err = true;
}
if (e.Op == BinaryExpr.Opcode.Gt || e.Op == BinaryExpr.Opcode.Ge) {
expr.Type = Type.Bool;
} else if (!err) {
expr.Type = e.E0.Type;
}
}
}
break;
case BinaryExpr.Opcode.In:
case BinaryExpr.Opcode.NotIn:
if (!UnifyTypes(e.E1.Type, new CollectionTypeProxy(e.E0.Type))) {
Error(expr, "second argument to {0} must be a set or sequence of type {1} (instead got {2})", BinaryExpr.OpcodeString(e.Op), e.E0.Type, e.E1.Type);
}
expr.Type = Type.Bool;
break;
case BinaryExpr.Opcode.Div:
case BinaryExpr.Opcode.Mod:
if (!UnifyTypes(e.E0.Type, Type.Int)) {
Error(expr, "first argument to {0} must be of type int (instead got {1})", BinaryExpr.OpcodeString(e.Op), e.E0.Type);
}
if (!UnifyTypes(e.E1.Type, Type.Int)) {
Error(expr, "second argument to {0} must be of type int (instead got {1})", BinaryExpr.OpcodeString(e.Op), e.E1.Type);
}
expr.Type = Type.Int;
break;
default:
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected operator
}
e.ResolvedOp = ResolveOp(e.Op, e.E1.Type);
} else if (expr is QuantifierExpr) {
QuantifierExpr e = (QuantifierExpr)expr;
int prevErrorCount = ErrorCount;
scope.PushMarker();
foreach (BoundVar v in e.BoundVars) {
if (!scope.Push(v.Name, v)) {
Error(v, "Duplicate bound-variable name: {0}", v.Name);
}
ResolveType(v.tok, v.Type);
}
if (e.Range != null) {
ResolveExpression(e.Range, twoState);
Contract.Assert(e.Range.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Range.Type, Type.Bool)) {
Error(expr, "range of quantifier must be of type bool (instead got {0})", e.Range.Type);
}
}
ResolveExpression(e.Term, twoState);
Contract.Assert(e.Term.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Term.Type, Type.Bool)) {
Error(expr, "body of quantifier must be of type bool (instead got {0})", e.Term.Type);
}
// Since the body is more likely to infer the types of the bound variables, resolve it
// first (above) and only then resolve the attributes (below).
ResolveAttributes(e.Attributes, twoState);
scope.PopMarker();
expr.Type = Type.Bool;
if (prevErrorCount == ErrorCount) {
var missingBounds = new List();
e.Bounds = DiscoverBounds(e.tok, e.BoundVars, e.LogicalBody(), e is ExistsExpr, missingBounds);
if (missingBounds.Count != 0) {
e.MissingBounds = missingBounds;
}
}
} else if (expr is SetComprehension) {
var e = (SetComprehension)expr;
int prevErrorCount = ErrorCount;
scope.PushMarker();
foreach (BoundVar v in e.BoundVars) {
if (!scope.Push(v.Name, v)) {
Error(v, "Duplicate bound-variable name: {0}", v.Name);
}
ResolveType(v.tok, v.Type);
}
ResolveExpression(e.Range, twoState);
Contract.Assert(e.Range.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Range.Type, Type.Bool)) {
Error(expr, "range of comprehension must be of type bool (instead got {0})", e.Range.Type);
}
ResolveExpression(e.Term, twoState);
Contract.Assert(e.Term.Type != null); // follows from postcondition of ResolveExpression
ResolveAttributes(e.Attributes, twoState);
scope.PopMarker();
expr.Type = new SetType(e.Term.Type);
if (prevErrorCount == ErrorCount) {
var missingBounds = new List();
e.Bounds = DiscoverBounds(e.tok, e.BoundVars, e.Range, true, missingBounds);
if (missingBounds.Count != 0) {
e.MissingBounds = missingBounds;
foreach (var bv in e.MissingBounds) {
Error(expr, "a set comprehension must produce a finite set, but Dafny's heuristics can't figure out how to produce a bounded set of values for '{0}'", bv.Name);
}
}
}
} else if (expr is WildcardExpr) {
expr.Type = new SetType(new ObjectType());
} else if (expr is PredicateExpr) {
var e = (PredicateExpr)expr;
ResolveExpression(e.Guard, twoState);
Contract.Assert(e.Guard.Type != null); // follows from postcondition of ResolveExpression
ResolveExpression(e.Body, twoState);
Contract.Assert(e.Body.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Guard.Type, Type.Bool)) {
Error(expr, "guard condition in {0} expression must be a boolean (instead got {1})", e.Kind, e.Guard.Type);
}
expr.Type = e.Body.Type;
} else if (expr is ITEExpr) {
ITEExpr e = (ITEExpr)expr;
ResolveExpression(e.Test, twoState);
Contract.Assert(e.Test.Type != null); // follows from postcondition of ResolveExpression
ResolveExpression(e.Thn, twoState);
Contract.Assert(e.Thn.Type != null); // follows from postcondition of ResolveExpression
ResolveExpression(e.Els, twoState);
Contract.Assert(e.Els.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.Test.Type, Type.Bool)) {
Error(expr, "guard condition in if-then-else expression must be a boolean (instead got {0})", e.Test.Type);
}
if (UnifyTypes(e.Thn.Type, e.Els.Type)) {
expr.Type = e.Thn.Type;
} else {
Error(expr, "the two branches of an if-then-else expression must have the same type (got {0} and {1})", e.Thn.Type, e.Els.Type);
}
} else if (expr is MatchExpr) {
MatchExpr me = (MatchExpr)expr;
Contract.Assert(!twoState); // currently, match expressions are allowed only at the outermost level of function bodies
if (matchVarContext == null) {
Error(me, "'match' expressions are not supported in this context");
matchVarContext = new List();
}
ResolveExpression(me.Source, twoState);
Contract.Assert(me.Source.Type != null); // follows from postcondition of ResolveExpression
UserDefinedType sourceType = null;
DatatypeDecl dtd = null;
Dictionary subst = new Dictionary();
if (me.Source.Type.IsDatatype) {
sourceType = (UserDefinedType)me.Source.Type;
dtd = cce.NonNull((DatatypeDecl)sourceType.ResolvedClass);
}
Dictionary ctors;
IVariable goodMatchVariable = null;
if (dtd == null) {
Error(me.Source, "the type of the match source expression must be a datatype (instead found {0})", me.Source.Type);
ctors = null;
} else {
Contract.Assert(sourceType != null); // dtd and sourceType are set together above
ctors = datatypeCtors[dtd];
Contract.Assert(ctors != null); // dtd should have been inserted into datatypeCtors during a previous resolution stage
IdentifierExpr ie = me.Source.Resolved as IdentifierExpr;
if (ie == null || !(ie.Var is Formal || ie.Var is BoundVar)) {
Error(me.Source.tok, "match source expression must be a formal parameter of the enclosing function or an enclosing match expression");
} else if (!matchVarContext.Contains(ie.Var)) {
Error(me.Source.tok, "match source expression '{0}' has already been used as a match source expression in this context", ie.Var.Name);
} else {
goodMatchVariable = ie.Var;
}
// build the type-parameter substitution map for this use of the datatype
for (int i = 0; i < dtd.TypeArgs.Count; i++) {
subst.Add(dtd.TypeArgs[i], sourceType.TypeArgs[i]);
}
}
Dictionary memberNamesUsed = new Dictionary(); // this is really a set
expr.Type = new InferredTypeProxy();
foreach (MatchCaseExpr mc in me.Cases) {
DatatypeCtor ctor = null;
if (ctors != null) {
Contract.Assert(dtd != null);
if (!ctors.TryGetValue(mc.Id, out ctor)) {
Error(mc.tok, "member {0} does not exist in datatype {1}", mc.Id, dtd.Name);
} else {
Contract.Assert(ctor != null); // follows from postcondition of TryGetValue
mc.Ctor = ctor;
if (ctor.Formals.Count != mc.Arguments.Count) {
Error(mc.tok, "member {0} has wrong number of formals (found {1}, expected {2})", mc.Id, mc.Arguments.Count, ctor.Formals.Count);
}
if (memberNamesUsed.ContainsKey(mc.Id)) {
Error(mc.tok, "member {0} appears in more than one case", mc.Id);
} else {
memberNamesUsed.Add(mc.Id, null); // add mc.Id to the set of names used
}
}
}
scope.PushMarker();
int i = 0;
foreach (BoundVar v in mc.Arguments) {
if (!scope.Push(v.Name, v)) {
Error(v, "Duplicate parameter name: {0}", v.Name);
}
ResolveType(v.tok, v.Type);
if (ctor != null && i < ctor.Formals.Count) {
Formal formal = ctor.Formals[i];
Type st = SubstType(formal.Type, subst);
if (!UnifyTypes(v.Type, st)) {
Error(expr, "the declared type of the formal ({0}) does not agree with the corresponding type in the constructor's signature ({1})", v.Type, st);
}
v.IsGhost = formal.IsGhost;
}
i++;
}
List innerMatchVarContext = new List(matchVarContext);
if (goodMatchVariable != null) {
innerMatchVarContext.Remove(goodMatchVariable); // this variable is no longer available for matching
}
innerMatchVarContext.AddRange(mc.Arguments);
ResolveExpression(mc.Body, twoState, innerMatchVarContext);
Contract.Assert(mc.Body.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(expr.Type, mc.Body.Type)) {
Error(mc.Body.tok, "type of case bodies do not agree (found {0}, previous types {1})", mc.Body.Type, expr.Type);
}
scope.PopMarker();
}
if (dtd != null && memberNamesUsed.Count != dtd.Ctors.Count) {
// We could complain about the syntactic omission of constructors:
// Error(expr, "match expression does not cover all constructors");
// but instead we let the verifier do a semantic check.
// So, for now, record the missing constructors:
foreach (var ctr in dtd.Ctors) {
if (!memberNamesUsed.ContainsKey(ctr.Name)) {
me.MissingCases.Add(ctr);
}
}
Contract.Assert(memberNamesUsed.Count + me.MissingCases.Count == dtd.Ctors.Count);
}
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected expression
}
if (expr.Type == null) {
// some resolution error occurred
expr.Type = Type.Flexible;
}
}
///
/// Generate an error for every non-ghost feature used in "expr".
/// Requires "expr" to have been successfully resolved.
///
void CheckIsNonGhost(Expression expr) {
Contract.Requires(expr != null);
Contract.Requires(currentClass != null);
Contract.Requires(expr.WasResolved()); // this check approximates the requirement that "expr" be resolved
if (expr is IdentifierExpr) {
var e = (IdentifierExpr)expr;
if (e.Var != null && e.Var.IsGhost) {
Error(expr, "ghost variables are allowed only in specification contexts");
return;
}
} else if (expr is FieldSelectExpr) {
var e = (FieldSelectExpr)expr;
if (e.Field != null && e.Field.IsGhost) {
Error(expr, "ghost fields are allowed only in specification contexts");
return;
}
} else if (expr is FunctionCallExpr) {
var e = (FunctionCallExpr)expr;
if (e.Function != null) {
if (e.Function.IsGhost) {
Error(expr, "function calls are allowed only in specification contexts (consider declaring the function a 'function method')");
return;
}
// function is okay, so check all NON-ghost arguments
CheckIsNonGhost(e.Receiver);
for (int i = 0; i < e.Function.Formals.Count; i++) {
if (!e.Function.Formals[i].IsGhost) {
CheckIsNonGhost(e.Args[i]);
}
}
}
return;
} else if (expr is DatatypeValue) {
var e = (DatatypeValue)expr;
// check all NON-ghost arguments
for (int i = 0; i < e.Ctor.Formals.Count; i++) {
if (!e.Ctor.Formals[i].IsGhost) {
CheckIsNonGhost(e.Arguments[i]);
}
}
return;
} else if (expr is OldExpr) {
Error(expr, "old expressions are allowed only in specification and ghost contexts");
return;
} else if (expr is FreshExpr) {
Error(expr, "fresh expressions are allowed only in specification and ghost contexts");
return;
} else if (expr is AllocatedExpr) {
Error(expr, "allocated expressions are allowed only in specification and ghost contexts");
return;
} else if (expr is PredicateExpr) {
var e = (PredicateExpr)expr;
// ignore the guard
CheckIsNonGhost(e.Body);
return;
} else if (expr is BinaryExpr) {
var e = (BinaryExpr)expr;
switch (e.ResolvedOp) {
case BinaryExpr.ResolvedOpcode.RankGt:
case BinaryExpr.ResolvedOpcode.RankLt:
Error(expr, "rank comparisons are allowed only in specification and ghost contexts");
return;
default:
break;
}
} else if (expr is QuantifierExpr) {
var e = (QuantifierExpr)expr;
if (e.MissingBounds != null) {
foreach (var bv in e.MissingBounds) {
Error(expr, "quantifiers in non-ghost contexts must be compilable, but Dafny's heuristics can't figure out how to produce a bounded set of values for '{0}'", bv.Name);
}
return;
}
}
foreach (var ee in expr.SubExpressions) {
CheckIsNonGhost(ee);
}
}
///
/// If "!allowMethodCall" or if what is being called does not refer to a method, resolves "e" and returns "null".
/// Otherwise (that is, if "allowMethodCall" and what is being called refers to a method), resolves the receiver
/// of "e" but NOT the arguments, and returns a CallRhs corresponding to the call.
///
CallRhs ResolveFunctionCallExpr(FunctionCallExpr e, bool twoState, bool allowMethodCall) {
ResolveReceiver(e.Receiver, twoState);
Contract.Assert(e.Receiver.Type != null); // follows from postcondition of ResolveExpression
NonProxyType nptype;
MemberDecl member = ResolveMember(e.tok, e.Receiver.Type, e.Name, out nptype);
#if !NO_WORK_TO_BE_DONE
UserDefinedType ctype = (UserDefinedType)nptype;
#endif
if (member == null) {
// error has already been reported by ResolveMember
} else if (member is Method) {
if (allowMethodCall) {
// it's a method
return new CallRhs(e.tok, e.Receiver, e.Name, e.Args);
} else {
Error(e, "member {0} in type {1} refers to a method, but only functions can be used in this context", e.Name, cce.NonNull(ctype).Name);
}
} else if (!(member is Function)) {
Error(e, "member {0} in type {1} does not refer to a function", e.Name, cce.NonNull(ctype).Name);
} else {
Function function = (Function)member;
e.Function = function;
if (e.Receiver is StaticReceiverExpr && !function.IsStatic) {
Error(e, "an instance function must be selected via an object, not just a class name");
}
if (function.Formals.Count != e.Args.Count) {
Error(e, "wrong number of function arguments (got {0}, expected {1})", e.Args.Count, function.Formals.Count);
} else {
Contract.Assert(ctype != null); // follows from postcondition of ResolveMember
if (!function.IsStatic) {
if (!scope.AllowInstance && e.Receiver is ThisExpr) {
// The call really needs an instance, but that instance is given as 'this', which is not
// available in this context. In most cases, occurrences of 'this' inside e.Receiver would
// have been caught in the recursive call to resolve e.Receiver, but not the specific case
// of e.Receiver being 'this' (explicitly or implicitly), for that case needs to be allowed
// in the event that a static function calls another static function (and note that we need the
// type of the receiver in order to find the method, so we could not have made this check
// earlier).
Error(e.Receiver, "'this' is not allowed in a 'static' context");
} else if (e.Receiver is StaticReceiverExpr) {
Error(e.Receiver, "call to instance function requires an instance");
}
}
// build the type substitution map
Dictionary subst = new Dictionary();
for (int i = 0; i < ctype.TypeArgs.Count; i++) {
subst.Add(cce.NonNull(ctype.ResolvedClass).TypeArgs[i], ctype.TypeArgs[i]);
}
foreach (TypeParameter p in function.TypeArgs) {
subst.Add(p, new ParamTypeProxy(p));
}
// type check the arguments
for (int i = 0; i < function.Formals.Count; i++) {
Expression farg = e.Args[i];
ResolveExpression(farg, twoState);
Contract.Assert(farg.Type != null); // follows from postcondition of ResolveExpression
Type s = SubstType(function.Formals[i].Type, subst);
if (!UnifyTypes(farg.Type, s)) {
Error(e, "incorrect type of function argument {0} (expected {1}, got {2})", i, s, farg.Type);
}
}
e.Type = SubstType(function.ResultType, subst);
}
// Resolution termination check
if (currentFunction != null && currentFunction.EnclosingClass != null && function.EnclosingClass != null) {
ModuleDecl callerModule = currentFunction.EnclosingClass.Module;
ModuleDecl calleeModule = function.EnclosingClass.Module;
if (callerModule == calleeModule) {
// intra-module call; this is allowed; add edge in module's call graph
callerModule.CallGraph.AddEdge(currentFunction, function);
if (currentFunction == function) {
currentFunction.IsRecursive = true; // self recursion (mutual recursion is determined elsewhere)
}
} else if (calleeModule.IsDefaultModule) {
// all is fine: everything implicitly imports the default module
} else if (importGraph.Reaches(callerModule, calleeModule)) {
// all is fine: the callee is downstream of the caller
} else {
Error(e, "inter-module calls must follow the module import relation (so module {0} must transitively import {1})", callerModule.Name, calleeModule.Name);
}
}
}
return null;
}
///
/// If "!allowMethodCall", or if "e" does not designate a method call, resolves "e" and returns "null".
/// Otherwise, resolves all sub-parts of "e" and returns a (resolved) CallRhs expression representing the call.
///
CallRhs ResolveIdentifierSequence(IdentifierSequence e, bool twoState, bool allowMethodCall) {
// Look up "id" as follows:
// - local variable, parameter, or bound variable (if this clashes with something of interest, one can always rename the local variable locally)
// - type name (class or datatype)
// - unambiguous constructor name of a datatype (if two constructors have the same name, an error message is produced here)
// - field name (with implicit receiver) (if the field is ocluded by anything above, one can use an explicit "this.")
// Note, at present, modules do not give rise to new namespaces, which is something that should
// be changed in the language when modules are given more attention.
Expression r = null; // resolved version of e
CallRhs call = null;
TopLevelDecl decl;
Tuple pair;
Dictionary members;
MemberDecl member;
var id = e.Tokens[0];
if (scope.Find(id.val) != null) {
// ----- root is a local variable, parameter, or bound variable
r = new IdentifierExpr(id, id.val);
ResolveExpression(r, twoState);
r = ResolveSuffix(r, e, 1, twoState, allowMethodCall, out call);
} else if (classes.TryGetValue(id.val, out decl)) {
if (e.Tokens.Count == 1 && e.Arguments == null) {
Error(id, "name of type ('{0}') is used as a variable", id.val);
} else if (e.Tokens.Count == 1 && e.Arguments != null) {
Error(id, "name of type ('{0}') is used as a function", id.val);
// resolve the arguments nonetheless
foreach (var arg in e.Arguments) {
ResolveExpression(arg, twoState);
}
} else if (decl is ClassDecl) {
// ----- root is a class
var cd = (ClassDecl)decl;
r = ResolveSuffix(new StaticReceiverExpr(id, cd), e, 1, twoState, allowMethodCall, out call);
} else {
// ----- root is a datatype
var dt = (DatatypeDecl)decl; // otherwise, unexpected TopLevelDecl
var args = (e.Tokens.Count == 2 ? e.Arguments : null) ?? new List();
r = new DatatypeValue(id, id.val, e.Tokens[1].val, args);
ResolveExpression(r, twoState);
if (e.Tokens.Count != 2) {
r = ResolveSuffix(r, e, 2, twoState, allowMethodCall, out call);
}
}
} else if (allDatatypeCtors.TryGetValue(id.val, out pair)) {
// ----- root is a datatype constructor
if (pair.Item2) {
// there is more than one constructor with this name
Error(id, "the name '{0}' denotes a datatype constructor, but does not do so uniquely; add an explicit qualification (for example, '{1}.{0}')", id.val, pair.Item1.EnclosingDatatype.Name);
} else {
var args = (e.Tokens.Count == 1 ? e.Arguments : null) ?? new List();
r = new DatatypeValue(id, pair.Item1.EnclosingDatatype.Name, id.val, args);
ResolveExpression(r, twoState);
if (e.Tokens.Count != 1) {
r = ResolveSuffix(r, e, 1, twoState, allowMethodCall, out call);
}
}
} else if (classMembers.TryGetValue(currentClass, out members) && members.TryGetValue(id.val, out member)) {
// ----- field, function, or method
Expression receiver;
if (member.IsStatic) {
receiver = new StaticReceiverExpr(id, currentClass);
} else {
if (!scope.AllowInstance) {
Error(id, "'this' is not allowed in a 'static' context");
// nevertheless, set "receiver" to a value so we can continue resolution
}
receiver = new ImplicitThisExpr(id);
receiver.Type = GetThisType(id, currentClass); // resolve here
}
r = ResolveSuffix(receiver, e, 0, twoState, allowMethodCall, out call);
} else {
Error(id, "unresolved identifier: {0}", id.val);
// resolve arguments, if any
if (e.Arguments != null) {
foreach (var arg in e.Arguments) {
ResolveExpression(arg, twoState);
}
}
}
if (r != null) {
e.ResolvedExpression = r;
e.Type = r.Type;
}
return call;
}
///
/// Given resolved expression "r" and unresolved expressions e.Tokens[p..] and e.Arguments.
/// Returns a resolved version of the expression:
/// r . e.Tokens[p] . e.Tokens[p+1] ... . e.Tokens[e.Tokens.Count-1] ( e.Arguments )
/// Except, if "allowMethodCall" is "true" and the would-be-returned value designates a method
/// call, instead returns null and returns "call" as a non-null value.
///
Expression ResolveSuffix(Expression r, IdentifierSequence e, int p, bool twoState, bool allowMethodCall, out CallRhs call) {
Contract.Requires(r != null);
Contract.Requires(e != null);
Contract.Requires(0 <= p && p <= e.Tokens.Count);
Contract.Ensures((Contract.Result() != null && Contract.ValueAtReturn(out call) == null) ||
(allowMethodCall && Contract.Result() == null && Contract.ValueAtReturn(out call) != null));
call = null;
int nonCallArguments = e.Arguments == null ? e.Tokens.Count : e.Tokens.Count - 1;
for (; p < nonCallArguments; p++) {
r = new FieldSelectExpr(e.Tokens[p], r, e.Tokens[p].val);
ResolveExpression(r, twoState);
}
if (p < e.Tokens.Count) {
Contract.Assert(e.Arguments != null);
Dictionary members;
MemberDecl member;
UserDefinedType receiverType = UserDefinedType.DenotesClass(r.Type);
if (allowMethodCall &&
receiverType != null &&
classMembers.TryGetValue((ClassDecl)receiverType.ResolvedClass, out members) &&
members.TryGetValue(e.Tokens[p].val, out member) &&
member is Method) {
// method
call = new CallRhs(e.Tokens[p], r, e.Tokens[p].val, e.Arguments);
r = null;
} else {
r = new FunctionCallExpr(e.Tokens[p], e.Tokens[p].val, r, e.Arguments);
ResolveExpression(r, twoState);
}
} else if (e.Arguments != null) {
Contract.Assert(p == e.Tokens.Count);
Error(e.OpenParen, "non-function expression is called with parameters");
// resolve the arguments nonetheless
foreach (var arg in e.Arguments) {
ResolveExpression(arg, twoState);
}
}
return r;
}
///
/// Tries to find a bounded pool for each of the bound variables "bvars" of "expr". If this process
/// fails, then "null" is returned and the bound variables for which the process fails are added to "missingBounds".
/// Requires "expr" to be successfully resolved.
///
List DiscoverBounds(IToken tok, List bvars, Expression expr, bool polarity, List missingBounds) {
Contract.Requires(tok != null);
Contract.Requires(bvars != null);
Contract.Requires(missingBounds != null);
Contract.Requires(expr != null);
Contract.Requires(expr.Type != null); // a sanity check (but not a complete proof) that "expr" has been resolved
Contract.Ensures(
(Contract.Result>() != null &&
Contract.Result>().Count == bvars.Count &&
Contract.OldValue(missingBounds.Count) == missingBounds.Count) ||
(Contract.Result>() == null &&
Contract.OldValue(missingBounds.Count) < missingBounds.Count));
var bounds = new List();
bool foundError = false;
for (int j = 0; j < bvars.Count; j++) {
var bv = bvars[j];
if (bv.Type is BoolType) {
// easy
bounds.Add(new QuantifierExpr.BoolBoundedPool());
} else {
// Go through the conjuncts of the range expression look for bounds.
Expression lowerBound = bv.Type is NatType ? new LiteralExpr(bv.tok, new BigInteger(0)) : null;
Expression upperBound = null;
foreach (var conjunct in NormalizedConjuncts(expr, polarity)) {
var c = conjunct as BinaryExpr;
if (c == null) {
goto CHECK_NEXT_CONJUNCT;
}
var e0 = c.E0;
var e1 = c.E1;
int whereIsBv = SanitizeForBoundDiscovery(bvars, j, c.ResolvedOp, ref e0, ref e1);
if (whereIsBv < 0) {
goto CHECK_NEXT_CONJUNCT;
}
switch (c.ResolvedOp) {
case BinaryExpr.ResolvedOpcode.InSet:
if (whereIsBv == 0) {
bounds.Add(new QuantifierExpr.SetBoundedPool(e1));
goto CHECK_NEXT_BOUND_VARIABLE;
}
break;
case BinaryExpr.ResolvedOpcode.InMultiSet:
if (whereIsBv == 0) {
bounds.Add(new QuantifierExpr.SetBoundedPool(e1));
goto CHECK_NEXT_BOUND_VARIABLE;
}
break;
case BinaryExpr.ResolvedOpcode.InSeq:
if (whereIsBv == 0) {
bounds.Add(new QuantifierExpr.SeqBoundedPool(e1));
goto CHECK_NEXT_BOUND_VARIABLE;
}
break;
case BinaryExpr.ResolvedOpcode.EqCommon:
if (bv.Type is IntType) {
var otherOperand = whereIsBv == 0 ? e1 : e0;
bounds.Add(new QuantifierExpr.IntBoundedPool(otherOperand, Plus(otherOperand, 1)));
goto CHECK_NEXT_BOUND_VARIABLE;
}
break;
case BinaryExpr.ResolvedOpcode.Gt:
case BinaryExpr.ResolvedOpcode.Ge:
Contract.Assert(false); throw new cce.UnreachableException(); // promised by postconditions of NormalizedConjunct
case BinaryExpr.ResolvedOpcode.Lt:
if (whereIsBv == 0 && upperBound == null) {
upperBound = e1; // bv < E
} else if (whereIsBv == 1 && lowerBound == null) {
lowerBound = Plus(e0, 1); // E < bv
}
break;
case BinaryExpr.ResolvedOpcode.Le:
if (whereIsBv == 0 && upperBound == null) {
upperBound = Plus(e1, 1); // bv <= E
} else if (whereIsBv == 1 && lowerBound == null) {
lowerBound = e0; // E <= bv
}
break;
default:
break;
}
if (lowerBound != null && upperBound != null) {
// we have found two halves
bounds.Add(new QuantifierExpr.IntBoundedPool(lowerBound, upperBound));
goto CHECK_NEXT_BOUND_VARIABLE;
}
CHECK_NEXT_CONJUNCT: ;
}
// we have checked every conjunct in the range expression and still have not discovered good bounds
missingBounds.Add(bv); // record failing bound variable
foundError = true;
}
CHECK_NEXT_BOUND_VARIABLE: ; // should goto here only if the bound for the current variable has been discovered (otherwise, return with null from this method)
}
return foundError ? null : bounds;
}
///
/// If the return value is negative, the resulting "e0" and "e1" should not be used.
/// Otherwise, the following is true on return:
/// The new "e0 op e1" is equivalent to the old "e0 op e1".
/// One of "e0" and "e1" is the identifier "boundVars[bvi]"; the return value is either 0 or 1, and indicates which.
/// The other of "e0" and "e1" is an expression whose free variables are not among "boundVars[bvi..]".
/// Ensures that the resulting "e0" and "e1" are not ConcreteSyntaxExpression's.
///
int SanitizeForBoundDiscovery(List boundVars, int bvi, BinaryExpr.ResolvedOpcode op, ref Expression e0, ref Expression e1)
{
Contract.Requires(e0 != null);
Contract.Requires(e1 != null);
Contract.Requires(boundVars != null);
Contract.Requires(0 <= bvi && bvi < boundVars.Count);
Contract.Ensures(Contract.Result() < 2);
Contract.Ensures(!(Contract.ValueAtReturn(out e0) is ConcreteSyntaxExpression));
Contract.Ensures(!(Contract.ValueAtReturn(out e1) is ConcreteSyntaxExpression));
var bv = boundVars[bvi];
e0 = e0.Resolved;
e1 = e1.Resolved;
// make an initial assessment of where bv is; to continue, we need bv to appear in exactly one operand
var fv0 = FreeVariables(e0);
var fv1 = FreeVariables(e1);
Expression thisSide;
Expression thatSide;
int whereIsBv;
if (fv0.Contains(bv)) {
if (fv1.Contains(bv)) {
return -1;
}
whereIsBv = 0;
thisSide = e0; thatSide = e1;
} else if (fv1.Contains(bv)) {
whereIsBv = 1;
thisSide = e1; thatSide = e0;
} else {
return -1;
}
// Next, clean up the side where bv is by adjusting both sides of the expression
switch (op) {
case BinaryExpr.ResolvedOpcode.EqCommon:
case BinaryExpr.ResolvedOpcode.NeqCommon:
case BinaryExpr.ResolvedOpcode.Gt:
case BinaryExpr.ResolvedOpcode.Ge:
case BinaryExpr.ResolvedOpcode.Le:
case BinaryExpr.ResolvedOpcode.Lt:
// Repeatedly move additive or subtractive terms from thisSide to thatSide
while (true) {
var bin = thisSide as BinaryExpr;
if (bin == null) {
break; // done simplifying
} else if (bin.ResolvedOp == BinaryExpr.ResolvedOpcode.Add) {
// Change "A+B op C" into either "A op C-B" or "B op C-A", depending on where we find bv among A and B.
if (!FreeVariables(bin.E1).Contains(bv)) {
thisSide = bin.E0.Resolved;
thatSide = new BinaryExpr(bin.tok, BinaryExpr.Opcode.Sub, thatSide, bin.E1);
} else {
thisSide = bin.E1.Resolved;
thatSide = new BinaryExpr(bin.tok, BinaryExpr.Opcode.Sub, thatSide, bin.E0);
}
((BinaryExpr)thatSide).ResolvedOp = BinaryExpr.ResolvedOpcode.Sub;
thatSide.Type = bin.Type;
} else if (bin.ResolvedOp == BinaryExpr.ResolvedOpcode.Sub) {
// Change "A-B op C" in a similar way.
if (!FreeVariables(bin.E1).Contains(bv)) {
// change to "A op C+B"
thisSide = bin.E0.Resolved;
thatSide = new BinaryExpr(bin.tok, BinaryExpr.Opcode.Add, thatSide, bin.E1);
((BinaryExpr)thatSide).ResolvedOp = BinaryExpr.ResolvedOpcode.Add;
} else {
// In principle, change to "-B op C-A" and then to "B dualOp A-C". But since we don't want
// to change "op", we instead end with "A-C op B" and switch the mapping of thisSide/thatSide
// to e0/e1 (by inverting "whereIsBv").
thisSide = bin.E1.Resolved;
thatSide = new BinaryExpr(bin.tok, BinaryExpr.Opcode.Sub, bin.E0, thatSide);
((BinaryExpr)thatSide).ResolvedOp = BinaryExpr.ResolvedOpcode.Sub;
whereIsBv = 1 - whereIsBv;
}
thatSide.Type = bin.Type;
} else {
break; // done simplifying
}
}
break;
default:
break;
}
// Now, see if the interesting side is simply bv itself
if (thisSide is IdentifierExpr && ((IdentifierExpr)thisSide).Var == bv) {
// we're cool
} else {
// no, the situation is more complicated than we care to understand
return -1;
}
// Finally, check that the other side does not contain "bv" or any of the bound variables
// listed after "bv" in the quantifier.
var fv = FreeVariables(thatSide);
for (int i = bvi; i < boundVars.Count; i++) {
if (fv.Contains(boundVars[i])) {
return -1;
}
}
// As we return, also return the adjusted sides
if (whereIsBv == 0) {
e0 = thisSide; e1 = thatSide;
} else {
e0 = thatSide; e1 = thisSide;
}
return whereIsBv;
}
///
/// Returns all conjuncts of "expr" in "polarity" positions. That is, if "polarity" is "true", then
/// returns the conjuncts of "expr" in positive positions; else, returns the conjuncts of "expr" in
/// negative positions. The method considers a canonical-like form of the expression that pushes
/// negations inwards far enough that one can determine what the result is going to be (so, almost
/// a negation normal form).
/// As a convenience, arithmetic inequalities are rewritten so that the negation of an arithmetic
/// inequality is never returned and the comparisons > and >= are never returned; the negation of
/// a common equality or disequality is rewritten analogously.
/// Requires "expr" to be successfully resolved.
/// Ensures that what is returned is not a ConcreteSyntaxExpression.
///
IEnumerable NormalizedConjuncts(Expression expr, bool polarity) {
// We consider 5 cases. To describe them, define P(e)=Conjuncts(e,true) and N(e)=Conjuncts(e,false).
// * X ==> Y is treated as a shorthand for !X || Y, and so is described by the remaining cases
// * X && Y P(_) = P(X),P(Y) and N(_) = !(X && Y)
// * X || Y P(_) = (X || Y) and N(_) = N(X),N(Y)
// * !X P(_) = N(X) and N(_) = P(X)
// * else P(_) = else and N(_) = !else
// So for ==>, we have:
// * X ==> Y P(_) = P(!X || Y) = (!X || Y) = (X ==> Y)
// N(_) = N(!X || Y) = N(!X),N(Y) = P(X),N(Y)
expr = expr.Resolved;
// Binary expressions
var b = expr as BinaryExpr;
if (b != null) {
bool breakDownFurther = false;
bool p0 = polarity;
if (b.ResolvedOp == BinaryExpr.ResolvedOpcode.And) {
breakDownFurther = polarity;
} else if (b.ResolvedOp == BinaryExpr.ResolvedOpcode.Or) {
breakDownFurther = !polarity;
} else if (b.ResolvedOp == BinaryExpr.ResolvedOpcode.Imp) {
breakDownFurther = !polarity;
p0 = !p0;
}
if (breakDownFurther) {
foreach (var c in NormalizedConjuncts(b.E0, p0)) {
yield return c;
}
foreach (var c in NormalizedConjuncts(b.E1, polarity)) {
yield return c;
}
yield break;
}
}
// Unary expression
var u = expr as UnaryExpr;
if (u != null && u.Op == UnaryExpr.Opcode.Not) {
foreach (var c in NormalizedConjuncts(u.E, !polarity)) {
yield return c;
}
yield break;
}
// no other case applied, so return the expression or its negation, but first clean it up a little
b = expr as BinaryExpr;
if (b != null) {
BinaryExpr.Opcode newOp;
BinaryExpr.ResolvedOpcode newROp;
bool swapOperands;
switch (b.ResolvedOp) {
case BinaryExpr.ResolvedOpcode.Gt: // A > B yield polarity ? (B < A) : (A <= B);
newOp = polarity ? BinaryExpr.Opcode.Lt : BinaryExpr.Opcode.Le;
newROp = polarity ? BinaryExpr.ResolvedOpcode.Lt : BinaryExpr.ResolvedOpcode.Le;
swapOperands = polarity;
break;
case BinaryExpr.ResolvedOpcode.Ge: // A >= B yield polarity ? (B <= A) : (A < B);
newOp = polarity ? BinaryExpr.Opcode.Le : BinaryExpr.Opcode.Lt;
newROp = polarity ? BinaryExpr.ResolvedOpcode.Le : BinaryExpr.ResolvedOpcode.Lt;
swapOperands = polarity;
break;
case BinaryExpr.ResolvedOpcode.Le: // A <= B yield polarity ? (A <= B) : (B < A);
newOp = polarity ? BinaryExpr.Opcode.Le : BinaryExpr.Opcode.Lt;
newROp = polarity ? BinaryExpr.ResolvedOpcode.Le : BinaryExpr.ResolvedOpcode.Lt;
swapOperands = !polarity;
break;
case BinaryExpr.ResolvedOpcode.Lt: // A < B yield polarity ? (A < B) : (B <= A);
newOp = polarity ? BinaryExpr.Opcode.Lt : BinaryExpr.Opcode.Le;
newROp = polarity ? BinaryExpr.ResolvedOpcode.Lt : BinaryExpr.ResolvedOpcode.Le;
swapOperands = !polarity;
break;
case BinaryExpr.ResolvedOpcode.EqCommon: // A == B yield polarity ? (A == B) : (A != B);
newOp = polarity ? BinaryExpr.Opcode.Eq : BinaryExpr.Opcode.Neq;
newROp = polarity ? BinaryExpr.ResolvedOpcode.EqCommon : BinaryExpr.ResolvedOpcode.NeqCommon;
swapOperands = false;
break;
case BinaryExpr.ResolvedOpcode.NeqCommon: // A != B yield polarity ? (A != B) : (A == B);
newOp = polarity ? BinaryExpr.Opcode.Neq : BinaryExpr.Opcode.Eq;
newROp = polarity ? BinaryExpr.ResolvedOpcode.NeqCommon : BinaryExpr.ResolvedOpcode.EqCommon;
swapOperands = false;
break;
default:
goto JUST_RETURN_IT;
}
if (newROp != b.ResolvedOp || swapOperands) {
b = new BinaryExpr(b.tok, newOp, swapOperands ? b.E1 : b.E0, swapOperands ? b.E0 : b.E1);
b.ResolvedOp = newROp;
b.Type = Type.Bool;
yield return b;
yield break;
}
}
JUST_RETURN_IT: ;
if (polarity) {
yield return expr;
} else {
expr = new UnaryExpr(expr.tok, UnaryExpr.Opcode.Not, expr);
expr.Type = Type.Bool;
yield return expr;
}
}
Expression Plus(Expression e, int n) {
Contract.Requires(0 <= n);
var nn = new LiteralExpr(e.tok, n);
nn.Type = Type.Int;
var p = new BinaryExpr(e.tok, BinaryExpr.Opcode.Add, e, nn);
p.ResolvedOp = BinaryExpr.ResolvedOpcode.Add;
p.Type = Type.Int;
return p;
}
///
/// Returns the set of free variables in "expr".
/// Requires "expr" to be successfully resolved.
/// Ensures that the set returned has no aliases.
///
ISet FreeVariables(Expression expr) {
Contract.Requires(expr != null);
Contract.Ensures(expr.Type != null);
if (expr is IdentifierExpr) {
var e = (IdentifierExpr)expr;
return new HashSet() { e.Var };
} else if (expr is QuantifierExpr) {
var e = (QuantifierExpr)expr;
var s = FreeVariables(e.LogicalBody());
foreach (var bv in e.BoundVars) {
s.Remove(bv);
}
return s;
} else if (expr is MatchExpr) {
var e = (MatchExpr)expr;
var s = FreeVariables(e.Source);
foreach (MatchCaseExpr mc in e.Cases) {
var t = FreeVariables(mc.Body);
foreach (var bv in mc.Arguments) {
t.Remove(bv);
}
s.UnionWith(t);
}
return s;
} else {
ISet s = null;
foreach (var e in expr.SubExpressions) {
var t = FreeVariables(e);
if (s == null) {
s = t;
} else {
s.UnionWith(t);
}
}
return s == null ? new HashSet() : s;
}
}
void ResolveReceiver(Expression expr, bool twoState)
{
Contract.Requires(expr != null);
Contract.Requires(currentClass != null);
Contract.Ensures(expr.Type != null);
if (expr is ThisExpr && !expr.WasResolved()) {
// Allow 'this' here, regardless of scope.AllowInstance. The caller is responsible for
// making sure 'this' does not really get used when it's not available.
expr.Type = GetThisType(expr.tok, currentClass);
} else {
ResolveExpression(expr, twoState);
}
}
void ResolveSeqSelectExpr(SeqSelectExpr e, bool twoState, bool allowNonUnitArraySelection) {
Contract.Requires(e != null);
if (e.Type != null) {
// already resolved
return;
}
bool seqErr = false;
ResolveExpression(e.Seq, twoState);
Contract.Assert(e.Seq.Type != null); // follows from postcondition of ResolveExpression
Type elementType = new InferredTypeProxy();
Type expectedType;
if (e.SelectOne || allowNonUnitArraySelection) {
expectedType = new IndexableTypeProxy(elementType);
} else {
expectedType = new SeqType(elementType);
}
if (!UnifyTypes(e.Seq.Type, expectedType)) {
Error(e, "sequence/array selection requires a sequence or array (got {0})", e.Seq.Type);
seqErr = true;
}
if (e.E0 != null) {
ResolveExpression(e.E0, twoState);
Contract.Assert(e.E0.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.E0.Type, Type.Int)) {
Error(e.E0, "sequence/array selection requires integer indices (got {0})", e.E0.Type);
}
}
if (e.E1 != null) {
ResolveExpression(e.E1, twoState);
Contract.Assert(e.E1.Type != null); // follows from postcondition of ResolveExpression
if (!UnifyTypes(e.E1.Type, Type.Int)) {
Error(e.E1, "sequence/array selection requires integer indices (got {0})", e.E1.Type);
}
}
if (!seqErr) {
if (e.SelectOne) {
e.Type = elementType;
} else {
e.Type = new SeqType(elementType);
}
}
}
///
/// Note: this method is allowed to be called even if "type" does not make sense for "op", as might be the case if
/// resolution of the binary expression failed. If so, an arbitrary resolved opcode is returned.
///
BinaryExpr.ResolvedOpcode ResolveOp(BinaryExpr.Opcode op, Type operandType) {
Contract.Requires(operandType != null);
switch (op) {
case BinaryExpr.Opcode.Iff: return BinaryExpr.ResolvedOpcode.Iff;
case BinaryExpr.Opcode.Imp: return BinaryExpr.ResolvedOpcode.Imp;
case BinaryExpr.Opcode.And: return BinaryExpr.ResolvedOpcode.And;
case BinaryExpr.Opcode.Or: return BinaryExpr.ResolvedOpcode.Or;
case BinaryExpr.Opcode.Eq:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.SetEq;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSetEq;
} else if (operandType is SeqType) {
return BinaryExpr.ResolvedOpcode.SeqEq;
} else {
return BinaryExpr.ResolvedOpcode.EqCommon;
}
case BinaryExpr.Opcode.Neq:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.SetNeq;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSetNeq;
} else if (operandType is SeqType) {
return BinaryExpr.ResolvedOpcode.SeqNeq;
} else {
return BinaryExpr.ResolvedOpcode.NeqCommon;
}
case BinaryExpr.Opcode.Disjoint:
if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSetDisjoint;
} else {
return BinaryExpr.ResolvedOpcode.Disjoint;
}
case BinaryExpr.Opcode.Lt:
if (operandType.IsDatatype || operandType is DatatypeProxy) {
return BinaryExpr.ResolvedOpcode.RankLt;
} else if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.ProperSubset;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.ProperMultiSubset;
} else if (operandType is SeqType) {
return BinaryExpr.ResolvedOpcode.ProperPrefix;
} else {
return BinaryExpr.ResolvedOpcode.Lt;
}
case BinaryExpr.Opcode.Le:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.Subset;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSubset;
} else if (operandType is SeqType) {
return BinaryExpr.ResolvedOpcode.Prefix;
} else {
return BinaryExpr.ResolvedOpcode.Le;
}
case BinaryExpr.Opcode.Add:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.Union;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSetUnion;
} else if (operandType is SeqType) {
return BinaryExpr.ResolvedOpcode.Concat;
} else {
return BinaryExpr.ResolvedOpcode.Add;
}
case BinaryExpr.Opcode.Sub:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.SetDifference;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSetDifference;
} else {
return BinaryExpr.ResolvedOpcode.Sub;
}
case BinaryExpr.Opcode.Mul:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.Intersection;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSetIntersection;
} else {
return BinaryExpr.ResolvedOpcode.Mul;
}
case BinaryExpr.Opcode.Gt:
if (operandType.IsDatatype) {
return BinaryExpr.ResolvedOpcode.RankGt;
} else if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.ProperSuperset;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.ProperMultiSuperset;
} else {
return BinaryExpr.ResolvedOpcode.Gt;
}
case BinaryExpr.Opcode.Ge:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.Superset;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.MultiSuperset;
} else {
return BinaryExpr.ResolvedOpcode.Ge;
}
case BinaryExpr.Opcode.In:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.InSet;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.InMultiSet;
} else {
return BinaryExpr.ResolvedOpcode.InSeq;
}
case BinaryExpr.Opcode.NotIn:
if (operandType is SetType) {
return BinaryExpr.ResolvedOpcode.NotInSet;
} else if (operandType is MultiSetType) {
return BinaryExpr.ResolvedOpcode.NotInMultiSet;
} else {
return BinaryExpr.ResolvedOpcode.NotInSeq;
}
case BinaryExpr.Opcode.Div: return BinaryExpr.ResolvedOpcode.Div;
case BinaryExpr.Opcode.Mod: return BinaryExpr.ResolvedOpcode.Mod;
default:
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected operator
}
}
///
/// Returns whether or not 'expr' has any subexpression that uses some feature (like a ghost or quantifier)
/// that is allowed only in specification contexts.
/// Requires 'expr' to be a successfully resolved expression.
///
bool UsesSpecFeatures(Expression expr)
{
Contract.Requires(expr != null);
Contract.Requires(currentClass != null);
if (expr is LiteralExpr) {
return false;
} else if (expr is ThisExpr) {
return false;
} else if (expr is IdentifierExpr) {
IdentifierExpr e = (IdentifierExpr)expr;
return cce.NonNull(e.Var).IsGhost;
} else if (expr is DatatypeValue) {
DatatypeValue dtv = (DatatypeValue)expr;
return dtv.Arguments.Exists(arg => UsesSpecFeatures(arg));
} else if (expr is DisplayExpression) {
DisplayExpression e = (DisplayExpression)expr;
return e.Elements.Exists(ee => UsesSpecFeatures(ee));
} else if (expr is FieldSelectExpr) {
FieldSelectExpr e = (FieldSelectExpr)expr;
return cce.NonNull(e.Field).IsGhost || UsesSpecFeatures(e.Obj);
} else if (expr is SeqSelectExpr) {
SeqSelectExpr e = (SeqSelectExpr)expr;
return UsesSpecFeatures(e.Seq) ||
(e.E0 != null && UsesSpecFeatures(e.E0)) ||
(e.E1 != null && UsesSpecFeatures(e.E1));
} else if (expr is MultiSelectExpr) {
MultiSelectExpr e = (MultiSelectExpr)expr;
return UsesSpecFeatures(e.Array) || e.Indices.Exists(ee => UsesSpecFeatures(ee));
} else if (expr is SeqUpdateExpr) {
SeqUpdateExpr e = (SeqUpdateExpr)expr;
return UsesSpecFeatures(e.Seq) ||
(e.Index != null && UsesSpecFeatures(e.Index)) ||
(e.Value != null && UsesSpecFeatures(e.Value));
} else if (expr is FunctionCallExpr) {
FunctionCallExpr e = (FunctionCallExpr)expr;
if (cce.NonNull(e.Function).IsGhost) {
return true;
}
return e.Args.Exists(arg => UsesSpecFeatures(arg));
} else if (expr is OldExpr) {
OldExpr e = (OldExpr)expr;
return UsesSpecFeatures(e.E);
} else if (expr is FreshExpr) {
return true;
} else if (expr is AllocatedExpr) {
return true;
} else if (expr is UnaryExpr) {
UnaryExpr e = (UnaryExpr)expr;
return UsesSpecFeatures(e.E);
} else if (expr is BinaryExpr) {
BinaryExpr e = (BinaryExpr)expr;
if (e.ResolvedOp == BinaryExpr.ResolvedOpcode.RankLt || e.ResolvedOp == BinaryExpr.ResolvedOpcode.RankGt) {
return true;
}
return UsesSpecFeatures(e.E0) || UsesSpecFeatures(e.E1);
} else if (expr is ComprehensionExpr) {
if (expr is QuantifierExpr && ((QuantifierExpr)expr).Bounds == null) {
return true; // the quantifier cannot be compiled if the resolver found no bounds
}
return Contract.Exists(expr.SubExpressions, se => UsesSpecFeatures(se));
} else if (expr is SetComprehension) {
var e = (SetComprehension)expr;
return (e.Range != null && UsesSpecFeatures(e.Range)) || (e.Term != null && UsesSpecFeatures(e.Term));
} else if (expr is WildcardExpr) {
return false;
} else if (expr is PredicateExpr) {
var e = (PredicateExpr)expr;
return UsesSpecFeatures(e.Body);
} else if (expr is ITEExpr) {
ITEExpr e = (ITEExpr)expr;
return UsesSpecFeatures(e.Test) || UsesSpecFeatures(e.Thn) || UsesSpecFeatures(e.Els);
} else if (expr is MatchExpr) {
MatchExpr me = (MatchExpr)expr;
if (UsesSpecFeatures(me.Source)) {
return true;
}
return me.Cases.Exists(mc => UsesSpecFeatures(mc.Body));
} else if (expr is ConcreteSyntaxExpression) {
var e = (ConcreteSyntaxExpression)expr;
return e.ResolvedExpression != null && UsesSpecFeatures(e.ResolvedExpression);
} else {
Contract.Assert(false); throw new cce.UnreachableException(); // unexpected expression
}
}
}
class Scope where Thing : class {
[Rep] readonly List names = new List(); // a null means a marker
[Rep] readonly List things = new List();
[ContractInvariantMethod]
void ObjectInvariant()
{
Contract.Invariant(names != null);
Contract.Invariant(things != null);
Contract.Invariant(names.Count == things.Count);
Contract.Invariant(-1 <= scopeSizeWhereInstancesWereDisallowed && scopeSizeWhereInstancesWereDisallowed <= names.Count);
}
int scopeSizeWhereInstancesWereDisallowed = -1;
public bool AllowInstance {
get { return scopeSizeWhereInstancesWereDisallowed == -1; }
set
{Contract.Requires(AllowInstance && !value); // only allowed to change from true to false (that's all that's currently needed in Dafny); Pop is what can make the change in the other direction
scopeSizeWhereInstancesWereDisallowed = names.Count;
}
}
public void PushMarker() {
names.Add(null);
things.Add(null);
}
public void PopMarker() {
int n = names.Count;
while (true) {
n--;
if (names[n] == null) {
break;
}
}
names.RemoveRange(n, names.Count - n);
things.RemoveRange(n, things.Count - n);
if (names.Count < scopeSizeWhereInstancesWereDisallowed) {
scopeSizeWhereInstancesWereDisallowed = -1;
}
}
// Pushes name-->thing association and returns "true", if name has not already been pushed since the last marker.
// If name already has been pushed since the last marker, does nothing and returns "false".
public bool Push(string name, Thing thing) {
Contract.Requires(name != null);
Contract.Requires(thing != null);
if (Find(name, true) != null) {
return false;
} else {
names.Add(name);
things.Add(thing);
return true;
}
}
Thing Find(string name, bool topScopeOnly) {
Contract.Requires(name != null);
for (int n = names.Count; 0 <= --n; ) {
if (names[n] == null) {
if (topScopeOnly) {
return null; // no present
}
} else if (names[n] == name) {
Thing t = things[n];
Contract.Assert(t != null);
return t;
}
}
return null; // not present
}
public Thing Find(string name) {
Contract.Requires(name != null);
return Find(name, false);
}
public bool ContainsDecl(Thing t) {
return things.Exists(thing => thing == t);
}
}
}