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//-----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All Rights Reserved.
//
//-----------------------------------------------------------------------------
using System;
using System.Collections;
using Microsoft.Boogie;
using Microsoft.Boogie.VCExprAST;
using Microsoft.Contracts;
namespace VC {
public class VCContext
{
[Rep] public readonly Hashtable/*<int, Absy!>*/! Label2absy;
[Rep] public readonly ProverContext! Ctxt;
public VCContext(Hashtable/*<int, Absy!>*/! label2absy, ProverContext! ctxt)
{
this.Label2absy = label2absy;
this.Ctxt = ctxt;
// base();
}
}
#region A class to compute wlp of a passive command program
public class Wlp
{
public static VCExpr! Block(Block! b, VCExpr! N, VCContext! ctxt)
modifies ctxt.*;
{
VCExpressionGenerator! gen = ctxt.Ctxt.ExprGen;
VCExpr! res = N;
for (int i = b.Cmds.Length; --i>=0; )
{
res = Cmd((!) b.Cmds[i], res, ctxt);
}
int id = b.UniqueId;
expose (ctxt) {
ctxt.Label2absy[id] = b;
return gen.Implies(gen.LabelPos((!)id.ToString(), VCExpressionGenerator.True), res);
}
}
/// <summary>
/// Computes the wlp for an assert or assume command "cmd".
/// </summary>
public static VCExpr! Cmd(Cmd! cmd, VCExpr! N, VCContext! ctxt)
{
VCExpressionGenerator! gen = ctxt.Ctxt.ExprGen;
if (cmd is AssertCmd) {
AssertCmd ac = (AssertCmd)cmd;
VCExpr C = ctxt.Ctxt.BoogieExprTranslator.Translate(ac.Expr);
if (CommandLineOptions.Clo.vcVariety == CommandLineOptions.VCVariety.Doomed) {
return gen.Implies(C, N);
} else {
int id = ac.UniqueId;
ctxt.Label2absy[id] = ac;
switch (CommandLineOptions.Clo.UseSubsumption) {
case CommandLineOptions.SubsumptionOption.Never:
break;
case CommandLineOptions.SubsumptionOption.Always:
N = gen.Implies(C, N);
break;
case CommandLineOptions.SubsumptionOption.NotForQuantifiers:
if (!(C is VCExprQuantifier)) {
N = gen.Implies(C, N);
}
break;
default:
assert false; // unexpected case
}
// (MSchaef) Hack: This line might be useless, but at least it is not harmfull
// need to test it
if (CommandLineOptions.Clo.vcVariety == CommandLineOptions.VCVariety.Doomed) return gen.Implies(C, N);
return gen.And(gen.LabelNeg((!)id.ToString(), C), N);
}
} else if (cmd is AssumeCmd) {
AssumeCmd ac = (AssumeCmd)cmd;
return gen.Implies(ctxt.Ctxt.BoogieExprTranslator.Translate(ac.Expr), N);
} else {
assert false; // unexpected command
}
}
public static VCExpr! RegExpr(RE! r, VCExpr! N, VCContext! ctxt)
{
if ( r is AtomicRE )
{
AtomicRE ar = (AtomicRE) r;
return Block(ar.b, N, ctxt);
}
else if ( r is Sequential )
{
Sequential s = (Sequential) r;
return RegExpr(s.first, RegExpr(s.second, N, ctxt), ctxt);
}
else if ( r is Choice )
{
Choice ch = (Choice) r;
VCExpr! res;
if (ch.rs == null || ch.rs.Length==0)
{
res = N;
}
else
{
VCExpr currentWLP = RegExpr((!)ch.rs[0], N, ctxt);
for (int i = 1, n = ch.rs.Length; i < n; i++)
{
currentWLP = ctxt.Ctxt.ExprGen.And(currentWLP, RegExpr((!)ch.rs[i], N, ctxt));
}
res = currentWLP;
}
return res;
}
else
{
assert false; // unexpected RE subtype
}
}
}
#endregion
}
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