source: branches/2817-BinPackingSpeedup/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.Xml-5.5.0/TokenReader.cs @ 16351

// Copyright (c) 2009-2013 AlphaSierraPapa for the SharpDevelop Team
// 
// 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 System.Diagnostics;
using System.Linq;
using ICSharpCode.NRefactory.Editor;

namespace ICSharpCode.NRefactory.Xml
{
  class TokenReader
  {
    protected readonly ITextSource input;
    protected readonly int inputLength;
    int currentLocation;
    
    // CurrentLocation is assumed to be touched and the fact does not
    //   have to be recorded in this variable.
    // This stores any value bigger than that if applicable.
    // Actual value is max(currentLocation, maxTouchedLocation).
    int maxTouchedLocation;
    
    public int InputLength {
      get { return inputLength; }
    }
    
    public int CurrentLocation {
      get { return currentLocation; }
    }
    
    public int MaxTouchedLocation {
      // add 1 to currentLocation because single-char-peek does not increment maxTouchedLocation
      get { return Math.Max(currentLocation + 1, maxTouchedLocation); }
    }
    
    public TokenReader(ITextSource input)
    {
      this.input = input;
      this.inputLength = input.TextLength;
    }
    
    protected bool IsEndOfFile()
    {
      return currentLocation == inputLength;
    }
    
    protected bool HasMoreData()
    {
      return currentLocation < inputLength;
    }
    
    protected void AssertHasMoreData()
    {
      Log.Assert(HasMoreData(), "Unexpected end of file");
    }
    
    protected bool TryMoveNext()
    {
      if (currentLocation == inputLength) return false;
      
      currentLocation++;
      return true;
    }
    
    protected void Skip(int count)
    {
      Log.Assert(currentLocation + count <= inputLength, "Skipping after the end of file");
      currentLocation += count;
    }
    
    protected void GoBack(int oldLocation)
    {
      Log.Assert(oldLocation <= currentLocation, "Trying to move forward");
      // add 1 because single-char-peek does not increment maxTouchedLocation
      maxTouchedLocation = Math.Max(maxTouchedLocation, currentLocation + 1);
      currentLocation = oldLocation;
    }
    
    protected bool TryRead(char c)
    {
      if (currentLocation == inputLength) return false;
      
      if (input.GetCharAt(currentLocation) == c) {
        currentLocation++;
        return true;
      } else {
        return false;
      }
    }
    
    protected bool TryReadAnyOf(params char[] c)
    {
      if (currentLocation == inputLength) return false;
      
      if (c.Contains(input.GetCharAt(currentLocation))) {
        currentLocation++;
        return true;
      } else {
        return false;
      }
    }
    
    protected bool TryRead(string text)
    {
      if (TryPeek(text)) {
        currentLocation += text.Length;
        return true;
      } else {
        return false;
      }
    }
    
    protected bool TryPeekPrevious(char c, int back)
    {
      if (currentLocation - back == inputLength) return false;
      if (currentLocation - back < 0 ) return false;
      
      return input.GetCharAt(currentLocation - back) == c;
    }
    
    protected bool TryPeek(char c)
    {
      if (currentLocation == inputLength) return false;
      
      return input.GetCharAt(currentLocation) == c;
    }
    
    protected bool TryPeekAnyOf(params char[] chars)
    {
      if (currentLocation == inputLength) return false;
      
      return chars.Contains(input.GetCharAt(currentLocation));
    }
    
    protected bool TryPeek(string text)
    {
      if (!TryPeek(text[0])) return false; // Early exit
      
      maxTouchedLocation = Math.Max(maxTouchedLocation, currentLocation + text.Length);
      // The following comparison 'touches' the end of file - it does depend on the end being there
      if (currentLocation + text.Length > inputLength) return false;
      
      return input.GetText(currentLocation, text.Length) == text;
    }
    
    protected bool TryPeekWhiteSpace()
    {
      if (currentLocation == inputLength) return false;
      
      char c = input.GetCharAt(currentLocation);
      return ((int)c <= 0x20) && (c == ' ' || c == '\t' || c == '\n' || c == '\r');
    }
    
    // The move functions do not have to move if already at target
    // The move functions allow 'overriding' of the document length
    
    protected bool TryMoveTo(char c)
    {
      return TryMoveTo(c, inputLength);
    }
    
    protected bool TryMoveTo(char c, int inputLength)
    {
      if (currentLocation == inputLength) return false;
      int index = input.IndexOf(c, currentLocation, inputLength - currentLocation);
      if (index != -1) {
        currentLocation = index;
        return true;
      } else {
        currentLocation = inputLength;
        return false;
      }
    }
    
    protected bool TryMoveToAnyOf(params char[] c)
    {
      return TryMoveToAnyOf(c, inputLength);
    }
    
    protected bool TryMoveToAnyOf(char[] c, int inputLength)
    {
      if (currentLocation == inputLength) return false;
      int index = input.IndexOfAny(c, currentLocation, inputLength - currentLocation);
      if (index != -1) {
        currentLocation = index;
        return true;
      } else {
        currentLocation = inputLength;
        return false;
      }
    }
    
    protected bool TryMoveTo(string text)
    {
      return TryMoveTo(text, inputLength);
    }
    
    protected bool TryMoveTo(string text, int inputLength)
    {
      if (currentLocation == inputLength) return false;
      int index = input.IndexOf(text, currentLocation, inputLength - currentLocation, StringComparison.Ordinal);
      if (index != -1) {
        maxTouchedLocation = index + text.Length;
        currentLocation = index;
        return true;
      } else {
        currentLocation = inputLength;
        return false;
      }
    }
    
    protected bool TryMoveToNonWhiteSpace()
    {
      return TryMoveToNonWhiteSpace(inputLength);
    }
    
    protected bool TryMoveToNonWhiteSpace(int inputLength)
    {
      while(true) {
        if (currentLocation == inputLength) return false; // Reject end of file
        char c = input.GetCharAt(currentLocation);
        if (((int)c <= 0x20) && (c == ' ' || c == '\t' || c == '\n' || c == '\r')) {
          currentLocation++;                            // Accept white-space
          continue;
        } else {
          return true;  // Found non-white-space
        }
      }
    }
    
    /// <summary>
    /// Read a name token.
    /// The following characters are not allowed:
    ///   ""         End of file
    ///   " \n\r\t"  Whitesapce
    ///   "=\'\""    Attribute value
    ///   "&lt;>/?"  Tags
    /// </summary>
    /// <returns>Returns the length of the name</returns>
    protected bool TryReadName()
    {
      int start = currentLocation;
      // Keep reading up to invalid character
      while (HasMoreData()) {
        char c = input.GetCharAt(currentLocation);
        if (0x41 <= (int)c) {                                   // Accpet from 'A' onwards
          currentLocation++;
          continue;
        }
        if (c == ' ' || c == '\n' || c == '\r' || c == '\t' ||  // Reject whitesapce
            c == '=' || c == '\'' || c == '"'  ||               // Reject attributes
            c == '<' || c == '>'  || c == '/'  || c == '?') {   // Reject tags
          break;
        } else {
          currentLocation++;
          continue;                                            // Accept other character
        }
      }
      return currentLocation > start;
    }
    
    protected bool TryReadName(out string name)
    {
      int start = currentLocation;
      if (TryReadName()) {
        name = GetCachedString(GetText(start, currentLocation));
        return true;
      } else {
        name = string.Empty;
        return false;
      }
    }
    
    protected string GetText(int start, int end)
    {
      Log.Assert(end <= currentLocation, "Reading ahead of current location");
      return input.GetText(start, end - start);
    }
    
    Dictionary<string, string> stringCache = new Dictionary<string, string>();
    
    #if DEBUG
    int stringCacheRequestedCount;
    int stringCacheRequestedSize;
    int stringCacheStoredCount;
    int stringCacheStoredSize;
    #endif
    
    internal void PrintStringCacheStats()
    {
      #if DEBUG
      Log.WriteLine("String cache: Requested {0} ({1} bytes);  Actaully stored {2} ({3} bytes); {4}% stored", stringCacheRequestedCount, stringCacheRequestedSize, stringCacheStoredCount, stringCacheStoredSize, stringCacheRequestedSize == 0 ? 0 : stringCacheStoredSize * 100 / stringCacheRequestedSize);
      #endif
    }
    
    [Conditional("DEBUG")]
    void AddToRequestedSize(string text)
    {
      #if DEBUG
      stringCacheRequestedCount += 1;
      stringCacheRequestedSize += 8 + 2 * text.Length;
      #endif
    }
    
    [Conditional("DEBUG")]
    void AddToStoredSize(string text)
    {
      #if DEBUG
      stringCacheStoredCount += 1;
      stringCacheStoredSize += 8 + 2 * text.Length;
      #endif
    }
    
    protected string GetCachedString(string cached)
    {
      AddToRequestedSize(cached);
      // Do not bother with long strings
      if (cached.Length > 32) {
        AddToStoredSize(cached);
        return cached;
      }
      string result;
      if (stringCache.TryGetValue(cached, out result)) {
        // Get the instance from the cache instead
        return result;
      } else {
        // Add to cache
        AddToStoredSize(cached);
        stringCache.Add(cached, cached);
        return cached;
      }
    }
  }
}