source: branches/2870_AutoDiff-nuget/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Indentation/CSharp/IndentationReformatter.cs

// Copyright (c) 2014 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.Globalization;
using System.Text;

namespace ICSharpCode.AvalonEdit.Indentation.CSharp
{
  sealed class IndentationSettings
  {
    public string IndentString = "\t";
    /// <summary>Leave empty lines empty.</summary>
    public bool LeaveEmptyLines = true;
  }
  
  sealed class IndentationReformatter
  {
    /// <summary>
    /// An indentation block. Tracks the state of the indentation.
    /// </summary>
    struct Block
    {
      /// <summary>
      /// The indentation outside of the block.
      /// </summary>
      public string OuterIndent;
      
      /// <summary>
      /// The indentation inside the block.
      /// </summary>
      public string InnerIndent;
      
      /// <summary>
      /// The last word that was seen inside this block.
      /// Because parenthesis open a sub-block and thus don't change their parent's LastWord,
      /// this property can be used to identify the type of block statement (if, while, switch)
      /// at the position of the '{'.
      /// </summary>
      public string LastWord;
      
      /// <summary>
      /// The type of bracket that opened this block (, [ or {
      /// </summary>
      public char Bracket;
      
      /// <summary>
      /// Gets whether there's currently a line continuation going on inside this block.
      /// </summary>
      public bool Continuation;
      
      /// <summary>
      /// Gets whether there's currently a 'one-line-block' going on. 'one-line-blocks' occur
      /// with if statements that don't use '{}'. They are not represented by a Block instance on
      /// the stack, but are instead handled similar to line continuations.
      /// This property is an integer because there might be multiple nested one-line-blocks.
      /// As soon as there is a finished statement, OneLineBlock is reset to 0.
      /// </summary>
      public int OneLineBlock;
      
      /// <summary>
      /// The previous value of one-line-block before it was reset.
      /// Used to restore the indentation of 'else' to the correct level.
      /// </summary>
      public int PreviousOneLineBlock;
      
      public void ResetOneLineBlock()
      {
        PreviousOneLineBlock = OneLineBlock;
        OneLineBlock = 0;
      }
      
      /// <summary>
      /// Gets the line number where this block started.
      /// </summary>
      public int StartLine;
      
      public void Indent(IndentationSettings set)
      {
        Indent(set.IndentString);
      }
      
      public void Indent(string indentationString)
      {
        OuterIndent = InnerIndent;
        InnerIndent += indentationString;
        Continuation = false;
        ResetOneLineBlock();
        LastWord = "";
      }
      
      public override string ToString()
      {
        return string.Format(
          CultureInfo.InvariantCulture,
          "[Block StartLine={0}, LastWord='{1}', Continuation={2}, OneLineBlock={3}, PreviousOneLineBlock={4}]",
          this.StartLine, this.LastWord, this.Continuation, this.OneLineBlock, this.PreviousOneLineBlock);
      }
    }
    
    StringBuilder wordBuilder;
    Stack<Block> blocks; // blocks contains all blocks outside of the current
    Block block;  // block is the current block
    
    bool inString;
    bool inChar;
    bool verbatim;
    bool escape;
    
    bool lineComment;
    bool blockComment;
    
    char lastRealChar; // last non-comment char
    
    public void Reformat(IDocumentAccessor doc, IndentationSettings set)
    {
      Init();
      
      while (doc.MoveNext()) {
        Step(doc, set);
      }
    }
    
    public void Init()
    {
      wordBuilder = new StringBuilder();
      blocks = new Stack<Block>();
      block = new Block();
      block.InnerIndent = "";
      block.OuterIndent = "";
      block.Bracket = '{';
      block.Continuation = false;
      block.LastWord = "";
      block.OneLineBlock = 0;
      block.PreviousOneLineBlock = 0;
      block.StartLine = 0;
      
      inString = false;
      inChar   = false;
      verbatim = false;
      escape   = false;
      
      lineComment  = false;
      blockComment = false;
      
      lastRealChar = ' '; // last non-comment char
    }
    
    public void Step(IDocumentAccessor doc, IndentationSettings set)
    {
      string line = doc.Text;
      if (set.LeaveEmptyLines && line.Length == 0) return; // leave empty lines empty
      line = line.TrimStart();
      
      StringBuilder indent = new StringBuilder();
      if (line.Length == 0) {
        // Special treatment for empty lines:
        if (blockComment || (inString && verbatim))
          return;
        indent.Append(block.InnerIndent);
        indent.Append(Repeat(set.IndentString, block.OneLineBlock));
        if (block.Continuation)
          indent.Append(set.IndentString);
        if (doc.Text != indent.ToString())
          doc.Text = indent.ToString();
        return;
      }
      
      if (TrimEnd(doc))
        line = doc.Text.TrimStart();
      
      Block oldBlock = block;
      bool startInComment = blockComment;
      bool startInString = (inString && verbatim);
      
      #region Parse char by char
      lineComment = false;
      inChar = false;
      escape = false;
      if (!verbatim) inString = false;
      
      lastRealChar = '\n';
      
      char lastchar = ' ';
      char c = ' ';
      char nextchar = line[0];
      for (int i = 0; i < line.Length; i++) {
        if (lineComment) break; // cancel parsing current line
        
        lastchar = c;
        c = nextchar;
        if (i + 1 < line.Length)
          nextchar = line[i + 1];
        else
          nextchar = '\n';
        
        if (escape) {
          escape = false;
          continue;
        }
        
        #region Check for comment/string chars
        switch (c) {
          case '/':
            if (blockComment && lastchar == '*')
              blockComment = false;
            if (!inString && !inChar) {
              if (!blockComment && nextchar == '/')
                lineComment = true;
              if (!lineComment && nextchar == '*')
                blockComment = true;
            }
            break;
          case '#':
            if (!(inChar || blockComment || inString))
              lineComment = true;
            break;
          case '"':
            if (!(inChar || lineComment || blockComment)) {
              inString = !inString;
              if (!inString && verbatim) {
                if (nextchar == '"') {
                  escape = true; // skip escaped quote
                  inString = true;
                } else {
                  verbatim = false;
                }
              } else if (inString && lastchar == '@') {
                verbatim = true;
              }
            }
            break;
          case '\'':
            if (!(inString || lineComment || blockComment)) {
              inChar = !inChar;
            }
            break;
          case '\\':
            if ((inString && !verbatim) || inChar)
              escape = true; // skip next character
            break;
        }
        #endregion
        
        if (lineComment || blockComment || inString || inChar) {
          if (wordBuilder.Length > 0)
            block.LastWord = wordBuilder.ToString();
          wordBuilder.Length = 0;
          continue;
        }
        
        if (!Char.IsWhiteSpace(c) && c != '[' && c != '/') {
          if (block.Bracket == '{')
            block.Continuation = true;
        }
        
        if (Char.IsLetterOrDigit(c)) {
          wordBuilder.Append(c);
        } else {
          if (wordBuilder.Length > 0)
            block.LastWord = wordBuilder.ToString();
          wordBuilder.Length = 0;
        }
        
        #region Push/Pop the blocks
        switch (c) {
          case '{':
            block.ResetOneLineBlock();
            blocks.Push(block);
            block.StartLine = doc.LineNumber;
            if (block.LastWord == "switch") {
              block.Indent(set.IndentString + set.IndentString);
              /* oldBlock refers to the previous line, not the previous block
               * The block we want is not available anymore because it was never pushed.
               * } else if (oldBlock.OneLineBlock) {
              // Inside a one-line-block is another statement
              // with a full block: indent the inner full block
              // by one additional level
              block.Indent(set, set.IndentString + set.IndentString);
              block.OuterIndent += set.IndentString;
              // Indent current line if it starts with the '{' character
              if (i == 0) {
                oldBlock.InnerIndent += set.IndentString;
              }*/
            } else {
              block.Indent(set);
            }
            block.Bracket = '{';
            break;
          case '}':
            while (block.Bracket != '{') {
              if (blocks.Count == 0) break;
              block = blocks.Pop();
            }
            if (blocks.Count == 0) break;
            block = blocks.Pop();
            block.Continuation = false;
            block.ResetOneLineBlock();
            break;
          case '(':
          case '[':
            blocks.Push(block);
            if (block.StartLine == doc.LineNumber)
              block.InnerIndent = block.OuterIndent;
            else
              block.StartLine = doc.LineNumber;
            block.Indent(Repeat(set.IndentString, oldBlock.OneLineBlock) +
                         (oldBlock.Continuation ? set.IndentString : "") +
                         (i == line.Length - 1 ? set.IndentString : new String(' ', i + 1)));
            block.Bracket = c;
            break;
          case ')':
            if (blocks.Count == 0) break;
            if (block.Bracket == '(') {
              block = blocks.Pop();
              if (IsSingleStatementKeyword(block.LastWord))
                block.Continuation = false;
            }
            break;
          case ']':
            if (blocks.Count == 0) break;
            if (block.Bracket == '[')
              block = blocks.Pop();
            break;
          case ';':
          case ',':
            block.Continuation = false;
            block.ResetOneLineBlock();
            break;
          case ':':
            if (block.LastWord == "case" 
                || line.StartsWith("case ", StringComparison.Ordinal) 
                || line.StartsWith(block.LastWord + ":", StringComparison.Ordinal)) 
            {
              block.Continuation = false;
              block.ResetOneLineBlock();
            }
            break;
        }
        
        if (!Char.IsWhiteSpace(c)) {
          // register this char as last char
          lastRealChar = c;
        }
        #endregion
      }
      #endregion
      
      if (wordBuilder.Length > 0)
        block.LastWord = wordBuilder.ToString();
      wordBuilder.Length = 0;
      
      if (startInString) return;
      if (startInComment && line[0] != '*') return;
      if (doc.Text.StartsWith("//\t", StringComparison.Ordinal) || doc.Text == "//")
        return;
      
      if (line[0] == '}') {
        indent.Append(oldBlock.OuterIndent);
        oldBlock.ResetOneLineBlock();
        oldBlock.Continuation = false;
      } else {
        indent.Append(oldBlock.InnerIndent);
      }
      
      if (indent.Length > 0 && oldBlock.Bracket == '(' && line[0] == ')') {
        indent.Remove(indent.Length - 1, 1);
      } else if (indent.Length > 0 && oldBlock.Bracket == '[' && line[0] == ']') {
        indent.Remove(indent.Length - 1, 1);
      }
      
      if (line[0] == ':') {
        oldBlock.Continuation = true;
      } else if (lastRealChar == ':' && indent.Length >= set.IndentString.Length) {
        if (block.LastWord == "case" || line.StartsWith("case ", StringComparison.Ordinal) || line.StartsWith(block.LastWord + ":", StringComparison.Ordinal))
          indent.Remove(indent.Length - set.IndentString.Length, set.IndentString.Length);
      } else if (lastRealChar == ')') {
        if (IsSingleStatementKeyword(block.LastWord)) {
          block.OneLineBlock++;
        }
      } else if (lastRealChar == 'e' && block.LastWord == "else") {
        block.OneLineBlock = Math.Max(1, block.PreviousOneLineBlock);
        block.Continuation = false;
        oldBlock.OneLineBlock = block.OneLineBlock - 1;
      }
      
      if (doc.IsReadOnly) {
        // We can't change the current line, but we should accept the existing
        // indentation if possible (=if the current statement is not a multiline
        // statement).
        if (!oldBlock.Continuation && oldBlock.OneLineBlock == 0 &&
            oldBlock.StartLine == block.StartLine &&
            block.StartLine < doc.LineNumber && lastRealChar != ':')
        {
          // use indent StringBuilder to get the indentation of the current line
          indent.Length = 0;
          line = doc.Text; // get untrimmed line
          for (int i = 0; i < line.Length; ++i) {
            if (!Char.IsWhiteSpace(line[i]))
              break;
            indent.Append(line[i]);
          }
          // /* */ multiline comments have an extra space - do not count it
          // for the block's indentation.
          if (startInComment && indent.Length > 0 && indent[indent.Length - 1] == ' ') {
            indent.Length -= 1;
          }
          block.InnerIndent = indent.ToString();
        }
        return;
      }
      
      if (line[0] != '{') {
        if (line[0] != ')' && oldBlock.Continuation && oldBlock.Bracket == '{')
          indent.Append(set.IndentString);
        indent.Append(Repeat(set.IndentString, oldBlock.OneLineBlock));
      }
      
      // this is only for blockcomment lines starting with *,
      // all others keep their old indentation
      if (startInComment)
        indent.Append(' ');
      
      if (indent.Length != (doc.Text.Length - line.Length) ||
          !doc.Text.StartsWith(indent.ToString(), StringComparison.Ordinal) ||
          Char.IsWhiteSpace(doc.Text[indent.Length]))
      {
        doc.Text = indent.ToString() + line;
      }
    }
    
    static string Repeat(string text, int count)
    {
      if (count == 0)
        return string.Empty;
      if (count == 1)
        return text;
      StringBuilder b = new StringBuilder(text.Length * count);
      for (int i = 0; i < count; i++)
        b.Append(text);
      return b.ToString();
    }
    
    static bool IsSingleStatementKeyword(string keyword)
    {
      switch (keyword) {
        case "if":
        case "for":
        case "while":
        case "do":
        case "foreach":
        case "using":
        case "lock":
          return true;
        default:
          return false;
      }
    }
    
    static bool TrimEnd(IDocumentAccessor doc)
    {
      string line = doc.Text;
      if (!Char.IsWhiteSpace(line[line.Length - 1])) return false;
      
      // one space after an empty comment is allowed
      if (line.EndsWith("// ", StringComparison.Ordinal) || line.EndsWith("* ", StringComparison.Ordinal))
        return false;
      
      doc.Text = line.TrimEnd();
      return true;
    }
  }
}