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//
// Gendarme.Rules.Smells.Pattern class
//
// Authors:
// Néstor Salceda <nestor.salceda@gmail.com>
// Sebastien Pouliot <sebastien@ximian.com>
//
// (C) 2008 Néstor Salceda
// Copyright (C) 2010 Novell, Inc (http://www.novell.com)
//
// 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 Mono.Cecil;
using Mono.Cecil.Cil;
using Gendarme.Framework.Rocks;
namespace Gendarme.Rules.Smells {
internal sealed class Pattern {
Instruction[] instructions;
int[] prefixes;
bool? compilerGeneratedBlock;
bool? extractableToMethodBlock;
internal Pattern (Instruction[] instructions) {
if (instructions == null)
throw new ArgumentNullException ("instructions");
this.instructions = instructions;
}
// look for: isinst System.IDisposable
static bool IsInstanceOfIDisposable (Instruction ins)
{
if (ins.OpCode.Code != Code.Isinst)
return false;
return ((ins.Operand as TypeReference).FullName == "System.IDisposable");
}
// look for a virtual call to a specific method
static bool IsCallVirt (Instruction ins, string typeName, string methodName)
{
if (ins.OpCode.Code != Code.Callvirt)
return false;
MethodReference mr = (ins.Operand as MethodReference);
return ((mr != null) && (mr.Name == methodName) && (mr.DeclaringType.FullName == typeName));
}
// look for:
// callvirt System.Void System.IDisposable::Dispose()
// endfinally
static bool IsIDisposableDisposePattern (Instruction ins)
{
if (!IsCallVirt (ins, "System.IDisposable", "Dispose"))
return false;
return ins.Next.Is (Code.Endfinally);
}
// IIRC older xMCS generated that quite often
bool IsDoubleReturn {
get {
return ((Count > 1) && (instructions[Count - 1].OpCode.Code == Code.Ret) &&
(instructions[Count - 2].OpCode.Code == Code.Ret));
}
}
// small patterns that highly suggest they were compiler generated
bool ComputeUnlikelyUserPatterns ()
{
bool call = false;
for (int i = 0; i < Count; i++) {
Instruction ins = instructions [i];
// foreach
if (IsCallVirt (ins, "System.Collections.IEnumerator", "get_Current"))
return true;
if (IsCallVirt (ins, "System.Collections.IEnumerator", "MoveNext"))
return !call;
// if there's a unknown call then it's likely not (totally) compiler generated
call |= (ins.OpCode.FlowControl == FlowControl.Call);
// foreach
if (IsInstanceOfIDisposable (ins))
return true;
// foreach, using
if (IsIDisposableDisposePattern (ins))
return true;
}
return false;
}
internal bool IsCompilerGeneratedBlock {
get {
if (compilerGeneratedBlock == null)
compilerGeneratedBlock = ComputeUnlikelyUserPatterns () || IsDoubleReturn;
return (bool) compilerGeneratedBlock;
}
}
bool IsReturningCode {
get {
return ((Count == 4 &&
instructions[0].OpCode.StackBehaviourPush == StackBehaviour.Push1 &&
(instructions [1].OpCode.Code == Code.Brtrue || instructions [1].OpCode.Code == Code.Brtrue_S) &&
instructions[2].OpCode.StackBehaviourPush == StackBehaviour.Pushi &&
instructions[3].OpCode.Code == Code.Ret)
||
(Count > 1 &&
instructions[Count - 1].OpCode.Code == Code.Ret &&
instructions[Count - 2].OpCode.FlowControl == FlowControl.Cond_Branch));
}
}
internal bool IsExtractableToMethodBlock {
get {
if (extractableToMethodBlock == null)
extractableToMethodBlock = !IsReturningCode;
return (bool) extractableToMethodBlock;
}
}
internal void ComputePrefixes (MethodDefinition method)
{
MethodDefinition target = InstructionMatcher.Target;
InstructionMatcher.Target = method;
try {
int offset = 0;
if ((prefixes == null) || (prefixes.Length < instructions.Length))
prefixes = new int [instructions.Length];
for (int index = 1; index < instructions.Length; index++) {
while (offset > 0 &&
!InstructionMatcher.AreEquivalent (instructions [offset], instructions [index]))
offset = prefixes [offset - 1];
if (InstructionMatcher.AreEquivalent (instructions [offset], instructions [index]))
offset++;
prefixes [index] = offset;
}
}
finally {
InstructionMatcher.Target = target;
}
}
internal int Count {
get {
return instructions.Length;
}
}
internal Instruction this[int index] {
get {
return instructions[index];
}
}
internal int[] Prefixes {
get {
return prefixes;
}
}
}
}
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