mirror of https://github.com/icsharpcode/ILSpy.git
Daniel Grunwald
9 years ago
10 changed files with 685 additions and 15 deletions
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// Copyright (c) 2016 Daniel Grunwald
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// software and associated documentation files (the "Software"), to deal in the Software
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// without restriction, including without limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
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// to whom the Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all copies or
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// substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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using System; |
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using System.Collections.Generic; |
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namespace ICSharpCode.Decompiler.IL.Patterns |
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{ |
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/// <summary>
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/// Data holder for a single list matching operation.
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/// </summary>
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/// <remarks>
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/// Notes on backtracking:
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/// PerformMatch() may save backtracking-savepoints to the ListMatch instance.
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/// Each backtracking-savepoints is a Stack{int} with instructions of how to restore the saved state.
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/// When a savepoint is created by a PerformMatch() call, that call may be nested in several other PerformMatch() calls that operate on
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/// the same list.
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/// When leaving those calls (whether with a successful match or not), the outer PerformMatch() calls may push additional state onto
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/// all of the added backtracking-savepoints.
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/// When the overall list match fails but savepoints exists, the most recently added savepoint is restored by calling PerformMatch()
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/// with listMatch.restoreFrom set to that savepoint. Each PerformMatch() call must pop its state from the savepoint
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/// This state is popped again when resuming from the checkpoint.
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/// </remarks>
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public struct ListMatch |
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{ |
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/// <summary>
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/// The main list matching logic.
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/// </summary>
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/// <returns>Returns whether the list match was successful.
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/// If the method returns true, it adds the capture groups (if any) to the match.
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/// If the method returns false, the match object remains in a partially-updated state and needs to be restored
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/// before it can be reused.</returns>
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internal static bool DoMatch(IReadOnlyList<ILInstruction> patterns, IReadOnlyList<ILInstruction> syntaxList, ref Match match) |
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{ |
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ListMatch listMatch = new ListMatch(syntaxList); |
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do { |
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if (PerformMatchSequence(patterns, ref listMatch, ref match)) { |
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// If we have a successful match and it matches the whole list,
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// we are done.
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if (listMatch.SyntaxIndex == syntaxList.Count) |
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return true; |
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} |
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// Otherwise, restore a savepoint created by PerformMatch() and resume the matching logic at that savepoint.
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} while (listMatch.RestoreSavePoint(ref match)); |
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return false; |
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} |
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/// <summary>
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/// PerformMatch() for a sequence of patterns.
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/// </summary>
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/// <param name="patterns">List of patterns to match.</param>
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/// <param name="listMatch">Stores state about the current list match.</param>
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/// <param name="match">The match object, used to store global state during the match (such as the results of capture groups).</param>
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/// <returns>Returns whether all patterns were matched successfully against a part of the list.
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/// If the method returns true, it updates listMatch.SyntaxIndex to point to the next node that was not part of the match,
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/// and adds the capture groups (if any) to the match.
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/// If the method returns false, the listMatch and match objects remain in a partially-updated state and need to be restored
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/// before they can be reused.</returns>
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internal static bool PerformMatchSequence(IReadOnlyList<ILInstruction> patterns, ref ListMatch listMatch, ref Match match) |
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{ |
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// The patterns may create savepoints, so we need to save the 'i' variable
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// as part of those checkpoints.
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for (int i = listMatch.PopFromSavePoint() ?? 0; i < patterns.Count; i++) { |
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int startMarker = listMatch.GetSavePointStartMarker(); |
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bool success = patterns[i].PerformMatch(ref listMatch, ref match); |
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listMatch.PushToSavePoints(startMarker, i); |
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if (!success) |
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return false; |
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} |
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return true; |
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} |
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/// <summary>
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/// A savepoint that the list matching operation can be restored from.
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/// </summary>
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struct SavePoint |
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{ |
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internal readonly int CheckPoint; |
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internal readonly int SyntaxIndex; |
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internal readonly Stack<int> stack; |
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public SavePoint(int checkpoint, int syntaxIndex) |
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{ |
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this.CheckPoint = checkpoint; |
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this.SyntaxIndex = syntaxIndex; |
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this.stack = new Stack<int>(); |
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} |
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} |
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/// <summary>
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/// The syntax list we are matching against.
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/// </summary>
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internal readonly IReadOnlyList<ILInstruction> SyntaxList; |
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/// <summary>
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/// The current index in the syntax list.
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/// </summary>
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internal int SyntaxIndex; |
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ListMatch(IReadOnlyList<ILInstruction> syntaxList) |
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{ |
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this.SyntaxList = syntaxList; |
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this.SyntaxIndex = 0; |
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this.backtrackingStack = null; |
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this.restoreStack = null; |
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} |
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List<SavePoint> backtrackingStack; |
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Stack<int> restoreStack; |
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void AddSavePoint(SavePoint savepoint) |
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{ |
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if (backtrackingStack == null) |
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backtrackingStack = new List<SavePoint>(); |
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backtrackingStack.Add(savepoint); |
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} |
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internal void AddSavePoint(ref Match match, int data) |
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{ |
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var savepoint = new SavePoint(match.CheckPoint(), this.SyntaxIndex); |
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savepoint.stack.Push(data); |
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AddSavePoint(savepoint); |
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} |
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internal int GetSavePointStartMarker() |
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{ |
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return backtrackingStack != null ? backtrackingStack.Count : 0; |
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} |
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internal void PushToSavePoints(int startMarker, int data) |
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{ |
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for (int i = startMarker; i < backtrackingStack.Count; i++) { |
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backtrackingStack[i].stack.Push(data); |
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} |
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} |
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internal int? PopFromSavePoint() |
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{ |
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if (restoreStack == null || restoreStack.Count == 0) |
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return null; |
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return restoreStack.Pop(); |
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} |
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/// <summary>
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/// Restores the listmatch state from a savepoint.
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/// </summary>
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/// <returns>Returns whether a savepoint exists</returns>
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internal bool RestoreSavePoint(ref Match match) |
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{ |
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if (backtrackingStack == null || backtrackingStack.Count == 0) |
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return false; |
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var savepoint = backtrackingStack[backtrackingStack.Count - 1]; |
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backtrackingStack.RemoveAt(backtrackingStack.Count - 1); |
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match.RestoreCheckPoint(savepoint.CheckPoint); |
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this.SyntaxIndex = savepoint.SyntaxIndex; |
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restoreStack = savepoint.stack; |
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return true; |
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} |
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} |
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} |
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@ -0,0 +1,100 @@ |
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// Copyright (c) 2016 Daniel Grunwald
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// software and associated documentation files (the "Software"), to deal in the Software
|
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|
// without restriction, including without limitation the rights to use, copy, modify, merge,
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|
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
|
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// to whom the Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all copies or
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// substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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using System; |
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using System.Collections.Generic; |
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namespace ICSharpCode.Decompiler.IL.Patterns |
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{ |
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public class CaptureGroup {} |
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/// <summary>
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/// Data holder for the overall pattern matching operation.
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/// </summary>
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/// <remarks>
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/// This type is a struct in order to prevent unnecessary memory allocations during pattern matching.
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/// The default value <c>default(Match)</c> represents an unsuccessful match.
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/// </remarks>
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public struct Match |
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{ |
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static readonly List<KeyValuePair<CaptureGroup, ILInstruction>> emptyResults = new List<KeyValuePair<CaptureGroup, ILInstruction>>(); |
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List<KeyValuePair<CaptureGroup, ILInstruction>> results; |
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/// <summary>
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/// Gets whether the match was successful.
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/// </summary>
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public bool Success { |
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get { |
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return results != null; |
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} |
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internal set { |
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if (value) { |
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if (results == null) |
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results = emptyResults; |
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} else { |
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results = null; |
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} |
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} |
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} |
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/// <summary>
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/// Gets whether the match was successful.
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/// </summary>
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public static bool operator true(Match m) |
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{ |
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return m.Success; |
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} |
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/// <summary>
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/// Gets whether the match failed.
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/// </summary>
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public static bool operator false(Match m) |
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{ |
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return !m.Success; |
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} |
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internal void Add(CaptureGroup g, ILInstruction n) |
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{ |
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if (results == null) |
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results = new List<KeyValuePair<CaptureGroup, ILInstruction>>(); |
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results.Add(new KeyValuePair<CaptureGroup, ILInstruction>(g, n)); |
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} |
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internal int CheckPoint() |
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{ |
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return results != null ? results.Count : 0; |
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} |
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internal void RestoreCheckPoint(int checkPoint) |
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{ |
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if (results != null) |
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results.RemoveRange(checkPoint, results.Count - checkPoint); |
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} |
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public IEnumerable<ILInstruction> Get(CaptureGroup captureGroup) |
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{ |
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if (results != null) { |
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foreach (var pair in results) { |
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if (pair.Key == captureGroup) |
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yield return pair.Value; |
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} |
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} |
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} |
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} |
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} |
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