source: branches/2915-AbsoluteSymbol/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/IndentEngine/CacheIndentEngine.cs @ 15943

//
// CacheIndentEngine.cs
//
// Author:
//       Matej Miklečić <matej.miklecic@gmail.com>
//
// Copyright (c) 2013 Matej Miklečić (matej.miklecic@gmail.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 ICSharpCode.NRefactory.Editor;
using System;
using System.Collections.Generic;
using System.Linq;

namespace ICSharpCode.NRefactory.CSharp
{
  /// <summary>
  ///     Represents a decorator of an IStateMachineIndentEngine instance that provides
  ///     logic for reseting and updating the engine on text changed events.
  /// </summary>
  /// <remarks>
  ///     The decorator is based on periodical caching of the engine's state and
  ///     delegating all logic behind indentation to the currently active engine.
  /// </remarks>
  public class CacheIndentEngine : IStateMachineIndentEngine
  {

    #region Properties

    IStateMachineIndentEngine currentEngine;
    Stack<IStateMachineIndentEngine> cachedEngines = new Stack<IStateMachineIndentEngine>();

    #endregion

    #region Constructors

    /// <summary>
    ///     Creates a new CacheIndentEngine instance.
    /// </summary>
    /// <param name="decoratedEngine">
    ///     An instance of <see cref="IStateMachineIndentEngine"/> to which the
    ///     logic for indentation will be delegated.
    /// </param>
    /// <param name="cacheRate">
    ///     The number of chars between caching.
    /// </param>
    public CacheIndentEngine(IStateMachineIndentEngine decoratedEngine, int cacheRate = 2000)
    {
      this.currentEngine = decoratedEngine;
    }

    /// <summary>
    ///     Creates a new CacheIndentEngine instance from the given prototype.
    /// </summary>
    /// <param name="prototype">
    ///     A CacheIndentEngine instance.
    /// </param>
    public CacheIndentEngine(CacheIndentEngine prototype)
    {
      this.currentEngine = prototype.currentEngine.Clone();
    }

    #endregion

    #region IDocumentIndentEngine

    /// <inheritdoc />
    public IDocument Document {
      get { return currentEngine.Document; }
    }

    /// <inheritdoc />
    public string ThisLineIndent {
      get { return currentEngine.ThisLineIndent; }
    }

    /// <inheritdoc />
    public string NextLineIndent {
      get { return currentEngine.NextLineIndent; }
    }

    /// <inheritdoc />
    public string CurrentIndent {
      get { return currentEngine.CurrentIndent; }
    }

    /// <inheritdoc />
    public bool NeedsReindent {
      get { return currentEngine.NeedsReindent; }
    }

    /// <inheritdoc />
    public int Offset {
      get { return currentEngine.Offset; }
    }

    /// <inheritdoc />
    public TextLocation Location {
      get { return currentEngine.Location; }
    }

    /// <inheritdoc />
    public bool EnableCustomIndentLevels
    {
      get { return currentEngine.EnableCustomIndentLevels; }
      set { currentEngine.EnableCustomIndentLevels = value; }
    }

    /// <inheritdoc />
    public void Push(char ch)
    {
      currentEngine.Push(ch);
    }

    /// <inheritdoc />
    public void Reset()
    {
      currentEngine.Reset();
      cachedEngines.Clear();
    }

    /// <summary>
    /// Resets the engine to offset. Clears all cached engines after the given offset.
    /// </summary>
    public void ResetEngineToPosition(int offset)
    {
      // We are already there
      if (currentEngine.Offset <= offset)
        return;
      
      bool gotCachedEngine = false;
      while (cachedEngines.Count > 0) {
        var topEngine = cachedEngines.Peek();
        if (topEngine.Offset <= offset) {
          currentEngine = topEngine.Clone();
          gotCachedEngine = true;
          break;
        } else {
          cachedEngines.Pop();
        }
      }
      if (!gotCachedEngine)
        currentEngine.Reset();
    }

    /// <inheritdoc />
    /// <remarks>
    ///     If the <paramref name="position"/> is negative, the engine will
    ///     update to: document.TextLength + (offset % document.TextLength+1)
    ///     Otherwise it will update to: offset % document.TextLength+1
    /// </remarks>
    public void Update(int position)
    {
      const int BUFFER_SIZE = 2000;
      
      if (currentEngine.Offset == position) {
        //positions match, nothing to be done
        return;
      } else if (currentEngine.Offset > position) {
        //moving backwards, so reset from previous saved location
        ResetEngineToPosition(position);
      }

      // get the engine caught up
      int nextSave = (cachedEngines.Count == 0) ? BUFFER_SIZE : cachedEngines.Peek().Offset + BUFFER_SIZE;
      if (currentEngine.Offset + 1 == position) {
        char ch = currentEngine.Document.GetCharAt(currentEngine.Offset);
        currentEngine.Push(ch);
        if (currentEngine.Offset == nextSave)
          cachedEngines.Push(currentEngine.Clone());
      } else {
        //bulk copy characters in case buffer is unmanaged 
        //(faster if we reduce managed/unmanaged transitions)
        while (currentEngine.Offset < position) {
          int endCut = currentEngine.Offset + BUFFER_SIZE;
          if (endCut > position)
            endCut = position;
          string buffer = currentEngine.Document.GetText(currentEngine.Offset, endCut - currentEngine.Offset);
          foreach (char ch in buffer) {
            currentEngine.Push(ch);
            //ConsoleWrite ("pushing character '{0}'", ch);
            if (currentEngine.Offset == nextSave) {
              cachedEngines.Push(currentEngine.Clone());
              nextSave += BUFFER_SIZE;
            }
          }
        }
      }
    }

    public IStateMachineIndentEngine GetEngine(int offset)
    {
      ResetEngineToPosition(offset);
      return currentEngine;
    }

    #endregion

    #region IClonable

    /// <inheritdoc />
    public IStateMachineIndentEngine Clone()
    {
      return new CacheIndentEngine(this);
    }

    /// <inheritdoc />
    IDocumentIndentEngine IDocumentIndentEngine.Clone()
    {
      return Clone();
    }

    object ICloneable.Clone()
    {
      return Clone();
    }

    #endregion

    #region IStateMachineIndentEngine

    public bool IsInsidePreprocessorDirective {
      get { return currentEngine.IsInsidePreprocessorDirective; }
    }

    public bool IsInsidePreprocessorComment {
      get { return currentEngine.IsInsidePreprocessorComment; }
    }

    public bool IsInsideStringLiteral {
      get { return currentEngine.IsInsideStringLiteral; }
    }

    public bool IsInsideVerbatimString {
      get { return currentEngine.IsInsideVerbatimString; }
    }

    public bool IsInsideCharacter {
      get { return currentEngine.IsInsideCharacter; }
    }

    public bool IsInsideString {
      get { return currentEngine.IsInsideString; }
    }

    public bool IsInsideLineComment {
      get { return currentEngine.IsInsideLineComment; }
    }

    public bool IsInsideMultiLineComment {
      get { return currentEngine.IsInsideMultiLineComment; }
    }

    public bool IsInsideDocLineComment {
      get { return currentEngine.IsInsideDocLineComment; }
    }

    public bool IsInsideComment {
      get { return currentEngine.IsInsideComment; }
    }

    public bool IsInsideOrdinaryComment {
      get { return currentEngine.IsInsideOrdinaryComment; }
    }

    public bool IsInsideOrdinaryCommentOrString {
      get { return currentEngine.IsInsideOrdinaryCommentOrString; }
    }

    public bool LineBeganInsideVerbatimString {
      get { return currentEngine.LineBeganInsideVerbatimString; }
    }

    public bool LineBeganInsideMultiLineComment {
      get { return currentEngine.LineBeganInsideMultiLineComment; }
    }

    #endregion

  }
  /*
/   // <summary>
  ///     Represents a decorator of an IStateMachineIndentEngine instance that provides
  ///     logic for reseting and updating the engine on text changed events.
  /// </summary>
  /// <remarks>
  ///     The decorator is based on periodical caching of the engine's state and
  ///     delegating all logic behind indentation to the currently active engine.
  /// </remarks>
  public class CacheIndentEngine : IStateMachineIndentEngine
  {
    #region Properties
    
    /// <summary>
    ///     Represents the cache interval in number of chars pushed to the engine.
    /// </summary>
    /// <remarks>
    ///     When this many new chars are pushed to the engine, the currently active
    ///     engine gets cloned and added to the end of <see cref="cachedEngines"/>.
    /// </remarks>
    readonly int cacheRate;
    
    /// <summary>
    ///     Determines how much memory to reserve on initialization for the
    ///     cached engines.
    /// </summary>
    const int cacheCapacity = 25;
    
    /// <summary>
    ///     Currently active engine.
    /// </summary>
    /// <remarks>
    ///     Should be equal to the last engine in <see cref="cachedEngines"/>.
    /// </remarks>
    IStateMachineIndentEngine currentEngine;
    
    /// <summary>
    ///     List of cached engines sorted ascending by 
    ///     <see cref="IDocumentIndentEngine.Offset"/>.
    /// </summary>
    IStateMachineIndentEngine[] cachedEngines;
    
    /// <summary>
    ///     The index of the last cached engine in cachedEngines.
    /// </summary>
    /// <remarks>
    ///     Should be equal to: currentEngine.Offset / CacheRate
    /// </remarks>
    int lastCachedEngine;
    
    #endregion
    
    #region Constructors
    
    /// <summary>
    ///     Creates a new CacheIndentEngine instance.
    /// </summary>
    /// <param name="decoratedEngine">
    ///     An instance of <see cref="IStateMachineIndentEngine"/> to which the
    ///     logic for indentation will be delegated.
    /// </param>
    /// <param name="cacheRate">
    ///     The number of chars between caching.
    /// </param>
    public CacheIndentEngine(IStateMachineIndentEngine decoratedEngine, int cacheRate = 2000)
    {
      this.cachedEngines = new IStateMachineIndentEngine[cacheCapacity];
      
      this.cachedEngines[0] = decoratedEngine.Clone();
      this.currentEngine = this.cachedEngines[0].Clone();
      this.cacheRate = cacheRate;
    }
    
    /// <summary>
    ///     Creates a new CacheIndentEngine instance from the given prototype.
    /// </summary>
    /// <param name="prototype">
    ///     A CacheIndentEngine instance.
    /// </param>
    public CacheIndentEngine(CacheIndentEngine prototype)
    {
      this.cachedEngines = new IStateMachineIndentEngine[prototype.cachedEngines.Length];
      Array.Copy(prototype.cachedEngines, this.cachedEngines, prototype.cachedEngines.Length);
      
      this.lastCachedEngine = prototype.lastCachedEngine;
      this.currentEngine = prototype.currentEngine.Clone();
      this.cacheRate = prototype.cacheRate;
    }
    
    #endregion
    
    #region Methods
    
    /// <summary>
    ///     Performs caching of the <see cref="CacheIndentEngine.currentEngine"/>.
    /// </summary>
    void cache()
    {
      if (currentEngine.Offset % cacheRate != 0)
      {
        throw new Exception("The current engine's offset is not divisable with the cacheRate.");
      }
      
      // determine the new current engine from cachedEngines
      lastCachedEngine = currentEngine.Offset / cacheRate;
      
      if (cachedEngines.Length < lastCachedEngine + 1)
      {
        Array.Resize(ref cachedEngines, lastCachedEngine * 2);
      }
      
      cachedEngines[lastCachedEngine] = currentEngine.Clone();
    }
    
    #endregion
    
    #region IDocumentIndentEngine
    
    /// <inheritdoc />
    public IDocument Document
    {
      get { return currentEngine.Document; }
    }
    
    /// <inheritdoc />
    public string ThisLineIndent
    {
      get { return currentEngine.ThisLineIndent; }
    }
    
    /// <inheritdoc />
    public string NextLineIndent
    {
      get { return currentEngine.NextLineIndent; }
    }
    
    /// <inheritdoc />
    public string CurrentIndent
    {
      get { return currentEngine.CurrentIndent; }
    }
    
    /// <inheritdoc />
    public bool NeedsReindent
    {
      get { return currentEngine.NeedsReindent; }
    }
    
    /// <inheritdoc />
    public int Offset
    {
      get { return currentEngine.Offset; }
    }
    
    /// <inheritdoc />
    public TextLocation Location
    {
      get { return currentEngine.Location; }
    }
    
    /// <inheritdoc />
    public void Push(char ch)
    {
      currentEngine.Push(ch);
      
      if (currentEngine.Offset % cacheRate == 0)
      {
        cache();
      }
    }
    
    /// <inheritdoc />
    public void Reset()
    {
      currentEngine = cachedEngines[lastCachedEngine = 0];
    }
    
    /// <inheritdoc />
    /// <remarks>
    ///     If the <paramref name="offset"/> is negative, the engine will
    ///     update to: document.TextLength + (offset % document.TextLength+1)
    ///     Otherwise it will update to: offset % document.TextLength+1
    /// </remarks>
    public void Update(int offset)
    {
      // map the given offset to the [0, document.TextLength] interval
      // using modulo arithmetics
      offset %= Document.TextLength + 1;
      if (offset < 0)
      {
        offset += Document.TextLength + 1;
      }
      
      // check if the engine has to be updated to some previous offset
      if (currentEngine.Offset > offset)
      {
        // replace the currentEngine with the first one whose offset
        // is less then the given <paramref name="offset"/>
        lastCachedEngine =  offset / cacheRate;
        currentEngine = cachedEngines[lastCachedEngine].Clone();
      }
      
      // update the engine to the given offset
      while (Offset < offset)
      {
        Push(Document.GetCharAt(Offset));
      }
    }
    
    public IStateMachineIndentEngine GetEngine(int offset)
    {
      // map the given offset to the [0, document.TextLength] interval
      // using modulo arithmetics
      offset %= Document.TextLength + 1;
      if (offset < 0)
      {
        offset += Document.TextLength + 1;
      }
      
      // check if the engine has to be updated to some previous offset
      if (currentEngine.Offset > offset)
      {
        // replace the currentEngine with the first one whose offset
        // is less then the given <paramref name="offset"/>
        lastCachedEngine =  offset / cacheRate;
        return cachedEngines[lastCachedEngine].Clone();
      }
      
      return currentEngine;
    }
    
    #endregion
    
    #region IClonable
    
    /// <inheritdoc />
    public IStateMachineIndentEngine Clone()
    {
      return new CacheIndentEngine(this);
    }
    
    /// <inheritdoc />
    IDocumentIndentEngine IDocumentIndentEngine.Clone()
    {
      return Clone();
    }
    
    object ICloneable.Clone()
    {
      return Clone();
    }
    
    #endregion
    
    #region IStateMachineIndentEngine
    
    public bool IsInsidePreprocessorDirective
    {
      get { return currentEngine.IsInsidePreprocessorDirective; }
    }
    
    public bool IsInsidePreprocessorComment
    {
      get { return currentEngine.IsInsidePreprocessorComment; }
    }
    
    public bool IsInsideStringLiteral
    {
      get { return currentEngine.IsInsideStringLiteral; }
    }
    
    public bool IsInsideVerbatimString
    {
      get { return currentEngine.IsInsideVerbatimString; }
    }
    
    public bool IsInsideCharacter
    {
      get { return currentEngine.IsInsideCharacter; }
    }
    
    public bool IsInsideString
    {
      get { return currentEngine.IsInsideString; }
    }
    
    public bool IsInsideLineComment
    {
      get { return currentEngine.IsInsideLineComment; }
    }
    
    public bool IsInsideMultiLineComment
    {
      get { return currentEngine.IsInsideMultiLineComment; }
    }
    
    public bool IsInsideDocLineComment
    {
      get { return currentEngine.IsInsideDocLineComment; }
    }
    
    public bool IsInsideComment
    {
      get { return currentEngine.IsInsideComment; }
    }
    
    public bool IsInsideOrdinaryComment
    {
      get { return currentEngine.IsInsideOrdinaryComment; }
    }
    
    public bool IsInsideOrdinaryCommentOrString
    {
      get { return currentEngine.IsInsideOrdinaryCommentOrString; }
    }
    
    public bool LineBeganInsideVerbatimString
    {
      get { return currentEngine.LineBeganInsideVerbatimString; }
    }
    
    public bool LineBeganInsideMultiLineComment
    {
      get { return currentEngine.LineBeganInsideMultiLineComment; }
    }
    
    #endregion
  }
  
  */
}