summaryrefslogtreecommitdiff
path: root/Source/Core/AlphaEquality.cs
diff options
context:
space:
mode:
Diffstat (limited to 'Source/Core/AlphaEquality.cs')
-rw-r--r--Source/Core/AlphaEquality.cs324
1 files changed, 162 insertions, 162 deletions
diff --git a/Source/Core/AlphaEquality.cs b/Source/Core/AlphaEquality.cs
index 1d4a1d95..986cc4bd 100644
--- a/Source/Core/AlphaEquality.cs
+++ b/Source/Core/AlphaEquality.cs
@@ -1,162 +1,162 @@
-//-----------------------------------------------------------------------------
-//
-// Copyright (C) Microsoft Corporation. All Rights Reserved.
-//
-//-----------------------------------------------------------------------------
-
-using System.ComponentModel;
-
-namespace Microsoft.Boogie
-{
-
- using System;
- using System.IO;
- using System.Collections;
- using System.Collections.Generic;
- using System.Diagnostics;
- using System.Diagnostics.Contracts;
-
- public class AlphaEquality : IEqualityComparer<Expr>
- {
- private readonly DeBruijnRenamer deBruijn = new DeBruijnRenamer();
-
- bool IEqualityComparer<Expr>.Equals(Expr x, Expr y) {
- var nx = deBruijn.Rename(x);
- var ny = deBruijn.Rename(y);
- return BinderExpr.EqualWithAttributesAndTriggers(nx, ny);
- }
-
- int IEqualityComparer<Expr>.GetHashCode(Expr obj) {
- return 0;
- // Best we can do because GetHashCode for Expression don't respect its equality.
- // When it does, we can instead use:
- // return deBruijn.Rename(obj).GetHashCode();
- }
-
- // Renames expressions into deBruijn indicies, such as
- // (lambda x : int :: x + a)
- // into
- // (lambda bv#0 : int :: bv#0 + fv#0)
- // It does not handle type variables yet, but it could be added.
- //
- // This class could be made public, but it is not since the Rename method
- // could then leak FreeVariables out of here.
- private class DeBruijnRenamer : Duplicator
- {
-
- // Maps from index positions and types to new variables
- private readonly TypeDict<BoundVariable> boundVars =
- new TypeDict<BoundVariable>("bv", ti => new BoundVariable(Token.NoToken, ti));
-
- private readonly TypeDict<FreeVariable> freeVars =
- new TypeDict<FreeVariable>("fv", ti => new FreeVariable(ti));
-
- // These three variables are reset at the beginning of every renaming
- private int boundVarCount, freeVarCount;
- private Dictionary<Variable, FreeVariable> freeVarMap;
-
- // Cached, previous results
- private readonly Dictionary<Expr, Expr> cache = new Dictionary<Expr, Expr>();
-
- public Expr Rename(Expr e) {
- Expr ne;
- if (!cache.TryGetValue(e, out ne)) {
- boundVarCount = 0;
- freeVarCount = 0;
- freeVarMap = new Dictionary<Variable, FreeVariable>();
-
- ne = VisitExpr(e);
- cache[e] = ne;
-#if DEBUG_ALPHA_RENAMING
- var wr = new TokenTextWriter("<console>", Console.Out, true);
- Console.Write("nm( ");
- e.Emit(wr);
- Console.WriteLine(" )");
- Console.Write(" = ");
- ne.Emit(wr);
- Console.WriteLine("");
- Console.WriteLine("h = " + ne.GetHashCode());
-#endif
- }
- return ne;
- }
-
- public override BinderExpr VisitBinderExpr(BinderExpr node) {
- var subst = new Dictionary<Variable, Expr>();
- var newBound = new List<Variable>();
- foreach (var bv in node.Dummies) {
- var bvNew = boundVars[boundVarCount++, bv.TypedIdent.Type];
- newBound.Add(bvNew);
- subst[bv] = new IdentifierExpr(Token.NoToken, bvNew);
- }
- node.Dummies = this.VisitVariableSeq(newBound);
- node.Body = this.VisitExpr(Substituter.Apply(Substituter.SubstitutionFromHashtable(subst), node.Body));
- return node;
- }
-
- public override Variable VisitVariable(Variable node) {
- FreeVariable fv;
- var bv = node as BoundVariable;
- if (boundVars.ContainsValue(bv)) {
- return node;
- } else if (freeVarMap.TryGetValue(node, out fv)) {
- return fv;
- } else {
- return freeVarMap[node] = freeVars[freeVarCount++, node.TypedIdent.Type];
- }
- }
-
- public override Expr VisitIdentifierExpr(IdentifierExpr node) {
- var ie = (IdentifierExpr) base.VisitIdentifierExpr(node);
- // Need to fix up the name, since IdentifierExpr's equality also checks the name
- ie.Name = ie.Decl.TypedIdent.Name;
- return ie;
- }
-
- private class TypeDict<A>
- {
- private readonly Dictionary<Tuple<int, Type>, A> vars = new Dictionary<Tuple<int, Type>, A>();
-
- private readonly string Prefix; // either "bv" or "fv"
- private readonly Func<TypedIdent, A> Mk; // either new BoundVar or new FreeVar
-
- public TypeDict(string prefix, Func<TypedIdent, A> mk) {
- Prefix = prefix;
- Mk = mk;
- }
-
- // For debugging purposes, we create unique names when types differ, but the index are the same.
- private int created = 0;
-
- // Make sure that this index and this type is always mapped to the same variable
- public A this[int i, Type t] {
- get {
- A v;
- if (!vars.TryGetValue(Tuple.Create(i, t), out v)) {
- v = Mk(new TypedIdent(Token.NoToken, Prefix + i + "#" + created++, t));
- vars[Tuple.Create(i, t)] = v;
- }
- return v;
- }
- }
-
- public bool ContainsValue(A a) {
- return vars.ContainsValue(a);
- }
- }
-
- private class FreeVariable : Variable
- {
- public FreeVariable(TypedIdent ti) : base(Token.NoToken, ti) {}
-
- public override bool IsMutable {
- get { throw new cce.UnreachableException(); }
- }
-
- public override void Register(ResolutionContext rc) {
- throw new cce.UnreachableException();
- }
- }
- }
- }
-}
+//-----------------------------------------------------------------------------
+//
+// Copyright (C) Microsoft Corporation. All Rights Reserved.
+//
+//-----------------------------------------------------------------------------
+
+using System.ComponentModel;
+
+namespace Microsoft.Boogie
+{
+
+ using System;
+ using System.IO;
+ using System.Collections;
+ using System.Collections.Generic;
+ using System.Diagnostics;
+ using System.Diagnostics.Contracts;
+
+ public class AlphaEquality : IEqualityComparer<Expr>
+ {
+ private readonly DeBruijnRenamer deBruijn = new DeBruijnRenamer();
+
+ bool IEqualityComparer<Expr>.Equals(Expr x, Expr y) {
+ var nx = deBruijn.Rename(x);
+ var ny = deBruijn.Rename(y);
+ return BinderExpr.EqualWithAttributesAndTriggers(nx, ny);
+ }
+
+ int IEqualityComparer<Expr>.GetHashCode(Expr obj) {
+ return 0;
+ // Best we can do because GetHashCode for Expression don't respect its equality.
+ // When it does, we can instead use:
+ // return deBruijn.Rename(obj).GetHashCode();
+ }
+
+ // Renames expressions into deBruijn indicies, such as
+ // (lambda x : int :: x + a)
+ // into
+ // (lambda bv#0 : int :: bv#0 + fv#0)
+ // It does not handle type variables yet, but it could be added.
+ //
+ // This class could be made public, but it is not since the Rename method
+ // could then leak FreeVariables out of here.
+ private class DeBruijnRenamer : Duplicator
+ {
+
+ // Maps from index positions and types to new variables
+ private readonly TypeDict<BoundVariable> boundVars =
+ new TypeDict<BoundVariable>("bv", ti => new BoundVariable(Token.NoToken, ti));
+
+ private readonly TypeDict<FreeVariable> freeVars =
+ new TypeDict<FreeVariable>("fv", ti => new FreeVariable(ti));
+
+ // These three variables are reset at the beginning of every renaming
+ private int boundVarCount, freeVarCount;
+ private Dictionary<Variable, FreeVariable> freeVarMap;
+
+ // Cached, previous results
+ private readonly Dictionary<Expr, Expr> cache = new Dictionary<Expr, Expr>();
+
+ public Expr Rename(Expr e) {
+ Expr ne;
+ if (!cache.TryGetValue(e, out ne)) {
+ boundVarCount = 0;
+ freeVarCount = 0;
+ freeVarMap = new Dictionary<Variable, FreeVariable>();
+
+ ne = VisitExpr(e);
+ cache[e] = ne;
+#if DEBUG_ALPHA_RENAMING
+ var wr = new TokenTextWriter("<console>", Console.Out, true);
+ Console.Write("nm( ");
+ e.Emit(wr);
+ Console.WriteLine(" )");
+ Console.Write(" = ");
+ ne.Emit(wr);
+ Console.WriteLine("");
+ Console.WriteLine("h = " + ne.GetHashCode());
+#endif
+ }
+ return ne;
+ }
+
+ public override BinderExpr VisitBinderExpr(BinderExpr node) {
+ var subst = new Dictionary<Variable, Expr>();
+ var newBound = new List<Variable>();
+ foreach (var bv in node.Dummies) {
+ var bvNew = boundVars[boundVarCount++, bv.TypedIdent.Type];
+ newBound.Add(bvNew);
+ subst[bv] = new IdentifierExpr(Token.NoToken, bvNew);
+ }
+ node.Dummies = this.VisitVariableSeq(newBound);
+ node.Body = this.VisitExpr(Substituter.Apply(Substituter.SubstitutionFromHashtable(subst), node.Body));
+ return node;
+ }
+
+ public override Variable VisitVariable(Variable node) {
+ FreeVariable fv;
+ var bv = node as BoundVariable;
+ if (boundVars.ContainsValue(bv)) {
+ return node;
+ } else if (freeVarMap.TryGetValue(node, out fv)) {
+ return fv;
+ } else {
+ return freeVarMap[node] = freeVars[freeVarCount++, node.TypedIdent.Type];
+ }
+ }
+
+ public override Expr VisitIdentifierExpr(IdentifierExpr node) {
+ var ie = (IdentifierExpr) base.VisitIdentifierExpr(node);
+ // Need to fix up the name, since IdentifierExpr's equality also checks the name
+ ie.Name = ie.Decl.TypedIdent.Name;
+ return ie;
+ }
+
+ private class TypeDict<A>
+ {
+ private readonly Dictionary<Tuple<int, Type>, A> vars = new Dictionary<Tuple<int, Type>, A>();
+
+ private readonly string Prefix; // either "bv" or "fv"
+ private readonly Func<TypedIdent, A> Mk; // either new BoundVar or new FreeVar
+
+ public TypeDict(string prefix, Func<TypedIdent, A> mk) {
+ Prefix = prefix;
+ Mk = mk;
+ }
+
+ // For debugging purposes, we create unique names when types differ, but the index are the same.
+ private int created = 0;
+
+ // Make sure that this index and this type is always mapped to the same variable
+ public A this[int i, Type t] {
+ get {
+ A v;
+ if (!vars.TryGetValue(Tuple.Create(i, t), out v)) {
+ v = Mk(new TypedIdent(Token.NoToken, Prefix + i + "#" + created++, t));
+ vars[Tuple.Create(i, t)] = v;
+ }
+ return v;
+ }
+ }
+
+ public bool ContainsValue(A a) {
+ return vars.ContainsValue(a);
+ }
+ }
+
+ private class FreeVariable : Variable
+ {
+ public FreeVariable(TypedIdent ti) : base(Token.NoToken, ti) {}
+
+ public override bool IsMutable {
+ get { throw new cce.UnreachableException(); }
+ }
+
+ public override void Register(ResolutionContext rc) {
+ throw new cce.UnreachableException();
+ }
+ }
+ }
+ }
+}