80 lines
2.4 KiB
C#
80 lines
2.4 KiB
C#
//
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// NullExpr.cs
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//
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// Authors:
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// Alexander Chebaturkin (chebaturkin@gmail.com)
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//
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// Copyright (C) 2011 Alexander Chebaturkin
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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using System;
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using System.Collections.Generic;
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using Mono.CodeContracts.Static.ControlFlow;
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using Mono.CodeContracts.Static.DataStructures;
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namespace Mono.CodeContracts.Static.Analysis.ExpressionAnalysis.Expressions {
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sealed class NullExpr<TSymbolicValue> : Expr<TSymbolicValue> where TSymbolicValue : IEquatable<TSymbolicValue> {
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public static readonly Expr<TSymbolicValue> Instance = new NullExpr<TSymbolicValue> ();
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private NullExpr ()
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{
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}
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#region Overrides of Expression
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public override IEnumerable<TSymbolicValue> Variables
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{
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get { yield break; }
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}
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public override Result Decode<Data, Result, Visitor> (APC pc, TSymbolicValue dest, Visitor visitor, Data data)
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{
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return visitor.LoadNull (pc, dest, data);
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}
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public override Expr<TSymbolicValue> Substitute (IImmutableMap<TSymbolicValue, Sequence<TSymbolicValue>> substitutions)
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{
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return this;
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}
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public override bool IsContained (IImmutableSet<TSymbolicValue> candidates)
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{
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return false;
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}
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public override bool Contains (TSymbolicValue symbol)
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{
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return false;
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}
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public override string ToString ()
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{
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return "Null()";
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}
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public override bool Equals (Expr<TSymbolicValue> other)
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{
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return other == this;
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}
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#endregion
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}
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}
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