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//
// Gendarme.Rules.Smells.InstructionMatcher class
//
// Authors:
// Néstor Salceda <nestor.salceda@gmail.com>
//
// (C) 2008 Néstor Salceda
//
// 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.Cecil;
using Mono.Cecil.Cil;
using Gendarme.Framework.Rocks;
namespace Gendarme.Rules.Smells {
internal static class InstructionMatcher {
static MethodDefinition current;
static MethodDefinition target;
internal static MethodDefinition Current {
get {
return current;
}
set {
current = value;
}
}
internal static MethodDefinition Target {
get {
return target;
}
set {
target = value;
}
}
static bool AreEquivalent (ParameterReference source, ParameterReference target)
{
if ((source == null) || (target == null))
return false;
int ss = source.Sequence - 1;
int ts = target.Sequence - 1;
if ((ss <= 0) || (ts <= 0))
return false;
ParameterDefinitionCollection cp = Current.Parameters;
ParameterDefinitionCollection tp = Target.Parameters;
return ((cp.Count > ss) && (tp.Count > ts)) ?
cp [ss].ParameterType.Equals (tp [ts].ParameterType) : false;
}
static bool AreEquivalent (VariableReference source, VariableReference target)
{
VariableDefinitionCollection cv = Current.Body.Variables;
VariableDefinitionCollection tv = Target.Body.Variables;
return cv.Count > source.Index && tv.Count > target.Index ?
cv [source.Index].VariableType.Equals (tv [target.Index].VariableType) : false;
}
internal static bool AreEquivalent (Instruction source, Instruction target)
{
if (source.OpCode.Code != target.OpCode.Code)
return false;
if (source.OpCode.Code == Code.Ldstr)
return true;
//Check the types in ldarg stuff. Sometimes this scheme
//could lead us to false positives. We need an analysis
//which depends on the context.
if (source.IsLoadArgument ()) {
// case where 'ldarg this' is used (p.Sequence would be 0)
if (!Current.HasParameters && !Target.HasParameters)
return true;
return AreEquivalent (source.GetParameter (Current), target.GetParameter (Target));
}
// The same for ldloc / stloc
if (source.IsLoadLocal () || source.IsStoreLocal ())
return AreEquivalent (source.GetVariable (Current), target.GetVariable (Target));
//WARNING: Dirty Evil Hack: this should be in the
//Pattern class
if (source.OpCode.Code == Code.Ret && source.Previous != null &&
(source.Previous.OpCode.StackBehaviourPush == StackBehaviour.Pushi ||
source.Previous.OpCode.Code == Code.Ldnull ||
source.Previous.OpCode.StackBehaviourPush == StackBehaviour.Push1))
return false;
//if (source.Operand != target.Operand)
if (source.Operand != null && target.Operand != null) {
// we're sure that target.Operand is of the same type as source.Operand (same OpCode is used)
Instruction si = (source.Operand as Instruction);
if (si != null)
return (si.Offset == ((Instruction) target.Operand).Offset);
IMetadataTokenProvider sm = (source.Operand as IMetadataTokenProvider);
if (sm != null)
return sm.Equals (target.Operand as IMetadataTokenProvider);
if (source.Operand == target.Operand)
return true;
// last chance: we do call ToString
if (source.Operand.ToString () != target.Operand.ToString ())
return false;
}
return true;
}
//This is a Knuth-Morris-Pratt string-matching algorithm, but applied to
//Mono.Cecil.Cil.Instruction instead of characters, and a
//InstructionCollection instead of string. I think it's a nice
//metaphor :)
internal static bool Match (Pattern pattern, InstructionCollection target)
{
int instructionsMatched = 0;
pattern.ComputePrefixes (Current);
for (int index = 0; index < target.Count; index++) {
while (instructionsMatched > 0 && !AreEquivalent (pattern[instructionsMatched], target[index]))
instructionsMatched = pattern.Prefixes[instructionsMatched - 1];
if (AreEquivalent (pattern[instructionsMatched], target[index]))
instructionsMatched++;
if (instructionsMatched == pattern.Count)
return true;
}
return false;
}
}
}
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