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//
// EvaluateExpressionVisitor.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2012 Alexander Chebaturkin
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
using Mono.CodeContracts.Static.DataStructures;
namespace Mono.CodeContracts.Static.Analysis.Numerical {
class EvaluateExpressionVisitor<TEnv, TVar, TExpr, TInterval, TNumeric> :
GenericExpressionVisitor<Counter<TEnv>, TInterval, TVar, TExpr>
where TEnv : IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric>
where TVar : IEquatable<TVar>
where TInterval : IntervalBase<TInterval, TNumeric> {
readonly
ConstToIntervalEvaluator
<IntervalContextBase<TInterval, TNumeric>, TVar, TExpr, TInterval, TNumeric> constToIntv;
readonly VariableOccurences occurences;
public Sequence<TVar> DuplicatedOccurences { get { return occurences.Duplicated; } }
public EvaluateExpressionVisitor (IExpressionDecoder<TVar, TExpr> decoder)
: base (decoder)
{
occurences = new VariableOccurences (decoder);
constToIntv =
new ConstToIntervalEvaluator
<IntervalContextBase<TInterval, TNumeric>, TVar, TExpr, TInterval, TNumeric> (
decoder);
}
public override TInterval Visit (TExpr expr, Counter<TEnv> data)
{
if (data.Count >= 10) // to avoid recursion if any
return Default (data);
var intv = base.Visit (expr, data.Incremented ());
if (intv == null)
return Default (data);
intv = RefineWithTypeRanges (intv, expr, data.Env);
var var = Decoder.UnderlyingVariable (expr);
TInterval current;
if (data.Env.TryGetValue (var, out current))
intv = intv.Meet (current);
return intv;
}
public override TInterval VisitConstant (TExpr expr, Counter<TEnv> data)
{
return constToIntv.Visit (expr, data.Env.Context);
}
public override TInterval VisitAddition (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultBinary (left, right, data, (d, l, r) => d.Env.Context.Add (l, r));
}
public override TInterval VisitDivision (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultBinary (left, right, data, (d, l, r) => d.Env.Context.Div (l, r));
}
public override TInterval VisitMultiply (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultBinary (left, right, data, (d, l, r) => d.Env.Context.Mul (l, r));
}
public override TInterval VisitSubtraction (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultBinary (left, right, data, (d, l, r) => d.Env.Context.Sub (l, r));
}
public override TInterval VisitEqual (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultComparisons (left, right, data);
}
public override TInterval VisitLessThan (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultComparisons (left, right, data);
}
public override TInterval VisitGreaterEqualThan (TExpr left, TExpr right, TExpr original,
Counter<TEnv> data)
{
return DefaultComparisons (left, right, data);
}
public override TInterval VisitLessEqualThan (TExpr left, TExpr right, TExpr original,
Counter<TEnv> data)
{
return DefaultComparisons (left, right, data);
}
public override TInterval VisitGreaterThan (TExpr left, TExpr right, TExpr original, Counter<TEnv> data)
{
return DefaultComparisons (left, right, data);
}
public override TInterval VisitUnknown (TExpr expr, Counter<TEnv> data)
{
occurences.Add (expr);
return Default (data);
}
protected override TInterval Default (Counter<TEnv> data)
{
return data.Env.Context.TopValue;
}
delegate TInterval BinaryEvaluator (Counter<TEnv> env, TInterval left, TInterval right);
TInterval DefaultBinary (TExpr left, TExpr right, Counter<TEnv> data, BinaryEvaluator binop)
{
occurences.Add (left, right);
var incremented = data.Incremented ();
var leftIntv = Visit (left, incremented);
var rightIntv = Visit (right, incremented);
return binop (data, leftIntv, rightIntv);
}
TInterval DefaultComparisons (TExpr left, TExpr right, Counter<TEnv> data)
{
occurences.Add (left, right);
return Default (data);
}
TInterval RefineWithTypeRanges (TInterval intv, TExpr expr, TEnv env)
{
switch (Decoder.TypeOf (expr)) {
case ExpressionType.Int32:
return env.Context.ApplyConversion (ExpressionOperator.ConvertToInt32, intv);
case ExpressionType.Bool:
return env.Context.ApplyConversion (ExpressionOperator.ConvertToInt32, intv);
default:
return intv;
}
}
class VariableOccurences {
readonly Dictionary<TVar, int> occurences;
readonly IExpressionDecoder<TVar, TExpr> decoder;
Sequence<TVar> duplicated;
public VariableOccurences (IExpressionDecoder<TVar, TExpr> decoder)
{
this.decoder = decoder;
occurences = new Dictionary<TVar, int> ();
duplicated = Sequence<TVar>.Empty;
}
public Sequence<TVar> Duplicated { get { return duplicated; } }
void Add (TVar var)
{
int cnt;
if (!occurences.TryGetValue (var, out cnt))
cnt = 0;
occurences[var] = cnt + 1;
if (cnt == 1) // if already was occurence
duplicated = duplicated.Cons (var);
}
public void Add (TExpr e)
{
Add (decoder.UnderlyingVariable (e));
}
public void Add (params TExpr[] exprs)
{
foreach (var expr in exprs)
Add (expr);
}
public override string ToString ()
{
return occurences.ToString ();
}
}
}
}
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