content: /*******************************************************************************
   * Copyright (c) 2000, 2008 IBM Corporation and others.
   * All rights reserved. This program and the accompanying materials
   * are made available under the terms of the Eclipse Public License v1.0
   * which accompanies this distribution, and is available at
   * http://www.eclipse.org/legal/epl-v10.html
   *
   * Contributors:
   *     IBM Corporation - initial API and implementation
   *******************************************************************************/
  package org.eclipse.wst.jsdt.internal.ui.text.java;
  
  import java.util.Arrays;
  
  import org.eclipse.core.runtime.Assert;
  import org.eclipse.jface.preference.IPreferenceStore;
  import org.eclipse.jface.text.BadLocationException;
  import org.eclipse.jface.text.DocumentCommand;
  import org.eclipse.jface.text.IAutoEditStrategy;
  import org.eclipse.jface.text.IDocument;
  import org.eclipse.jface.text.IRegion;
  import org.eclipse.jface.text.ITextSelection;
  import org.eclipse.jface.text.ITypedRegion;
  import org.eclipse.jface.text.Region;
  import org.eclipse.jface.text.TextSelection;
  import org.eclipse.jface.text.TextUtilities;
  import org.eclipse.text.edits.DeleteEdit;
  import org.eclipse.text.edits.MalformedTreeException;
  import org.eclipse.text.edits.ReplaceEdit;
  import org.eclipse.text.edits.TextEdit;
  import org.eclipse.ui.IEditorPart;
  import org.eclipse.ui.IWorkbenchPage;
  import org.eclipse.ui.texteditor.ITextEditorExtension2;
  import org.eclipse.ui.texteditor.ITextEditorExtension3;
  import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
  import org.eclipse.wst.jsdt.internal.ui.javaeditor.CompilationUnitEditor;
  import org.eclipse.wst.jsdt.internal.ui.text.SmartBackspaceManager;
  import org.eclipse.wst.jsdt.internal.ui.text.SmartBackspaceManager.UndoSpec;
  import org.eclipse.wst.jsdt.ui.PreferenceConstants;
  import org.eclipse.wst.jsdt.ui.text.IJavaScriptPartitions;
  
  /**
   * Modifies <code>DocumentCommand</code>s inserting semicolons and opening braces to place them
   * smartly, i.e. moving them to the end of a line if that is what the user expects.
   *
   * <p>In practice,  semicolons and braces (and the caret) are moved to the end of the line if they are typed
   * anywhere except for semicolons in a <code>for</code> statements definition. If the line contains a semicolon
   * or brace after the current caret position, the cursor is moved after it.</p>
   *
   * @see org.eclipse.jface.text.DocumentCommand
   * 
   */
  public class SmartSemicolonAutoEditStrategy implements IAutoEditStrategy {
  
  	/** String representation of a semicolon. */
  	private static final String SEMICOLON= ";"; //$NON-NLS-1$
  	/** Char representation of a semicolon. */
  	private static final char SEMICHAR= ';';
  	/** String represenattion of a opening brace. */
  	private static final String BRACE= "{"; //$NON-NLS-1$
  	/** Char representation of a opening brace */
  	private static final char BRACECHAR= '{';
  
  	private char fCharacter;
  	private String fPartitioning;
  
  	/**
  	 * Creates a new SmartSemicolonAutoEditStrategy.
  	 *
  	 * @param partitioning the document partitioning
  	 */
  	public SmartSemicolonAutoEditStrategy(String partitioning) {
  		fPartitioning= partitioning;
  	}
  
  	/*
  	 * @see org.eclipse.jface.text.IAutoEditStrategy#customizeDocumentCommand(org.eclipse.jface.text.IDocument, org.eclipse.jface.text.DocumentCommand)
  	 */
  	public void customizeDocumentCommand(IDocument document, DocumentCommand command) {
  		// 0: early pruning
  		// also customize if <code>doit</code> is false (so it works in code completion situations)
  		//		if (!command.doit)
  		//			return;
  
  		if (command.text == null)
  			return;
  
  		if (command.text.equals(SEMICOLON))
  			fCharacter= SEMICHAR;
  		else if (command.text.equals(BRACE))
  			fCharacter= BRACECHAR;
  		else
  			return;
  
  		IPreferenceStore store= JavaScriptPlugin.getDefault().getPreferenceStore();
  		if (fCharacter == SEMICHAR && !store.getBoolean(PreferenceConstants.EDITOR_SMART_SEMICOLON))
  			return;
  		if (fCharacter == BRACECHAR && !store.getBoolean(PreferenceConstants.EDITOR_SMART_OPENING_BRACE))
  			return;
  
  		IWorkbenchPage page= JavaScriptPlugin.getActivePage();
  		if (page == null)
  			return;
  		IEditorPart part= page.getActiveEditor();
  		if (!(part instanceof CompilationUnitEditor))
  			return;
  		CompilationUnitEditor editor= (CompilationUnitEditor)part;
  		if (editor.getInsertMode() != ITextEditorExtension3.SMART_INSERT || !editor.isEditable())
  			return;
  		ITextEditorExtension2 extension= (ITextEditorExtension2)editor.getAdapter(ITextEditorExtension2.class);
  		if (extension != null && !extension.validateEditorInputState())
  			return;
  		if (isMultilineSelection(document, command))
  			return;
  
  		// 1: find concerned line / position in java code, location in statement
  		int pos= command.offset;
  		ITextSelection line;
  		try {
  			IRegion l= document.getLineInformationOfOffset(pos);
  			line= new TextSelection(document, l.getOffset(), l.getLength());
  		} catch (BadLocationException e) {
  			return;
  		}
  
  		// 2: choose action based on findings (is for-Statement?)
  		// for now: compute the best position to insert the new character
  		int positionInLine= computeCharacterPosition(document, line, pos - line.getOffset(), fCharacter, fPartitioning);
  		int position= positionInLine + line.getOffset();
  
  		// never position before the current position!
  		if (position < pos)
  			return;
  
  		// never double already existing content
  		if (alreadyPresent(document, fCharacter, position))
  			return;
  
  		// don't do special processing if what we do is actually the normal behaviour
  		String insertion= adjustSpacing(document, position, fCharacter);
  		if (command.offset == position && insertion.equals(command.text))
  			return;
  
  		try {
  
  			final SmartBackspaceManager manager= (SmartBackspaceManager) editor.getAdapter(SmartBackspaceManager.class);
  			if (manager != null && JavaScriptPlugin.getDefault().getPreferenceStore().getBoolean(PreferenceConstants.EDITOR_SMART_BACKSPACE)) {
  				TextEdit e1= new ReplaceEdit(command.offset, command.text.length(), document.get(command.offset, command.length));
  				UndoSpec s1= new UndoSpec(command.offset + command.text.length(),
  						new Region(command.offset, 0),
  						new TextEdit[] {e1},
  						0,
  						null);
  
  				DeleteEdit smart= new DeleteEdit(position, insertion.length());
  				ReplaceEdit raw= new ReplaceEdit(command.offset, command.length, command.text);
  				UndoSpec s2= new UndoSpec(position + insertion.length(),
  						new Region(command.offset + command.text.length(), 0),
  						new TextEdit[] {smart, raw},
  						2,
  						s1);
  				manager.register(s2);
  			}
  
  			// 3: modify command
  			command.offset= position;
  			command.length= 0;
  			command.caretOffset= position;
  			command.text= insertion;
  			command.doit= true;
  			command.owner= null;
  		} catch (MalformedTreeException e) {
  			JavaScriptPlugin.log(e);
  		} catch (BadLocationException e) {
  			JavaScriptPlugin.log(e);
  		}
  
  
  	}
  
  	/**
  	 * Returns <code>true</code> if the document command is applied on a multi
  	 * line selection, <code>false</code> otherwise.
  	 *
  	 * @param document the document
  	 * @param command the command
  	 * @return <code>true</code> if <code>command</code> is a multiline command
  	 */
  	private boolean isMultilineSelection(IDocument document, DocumentCommand command) {
  		try {
  			return document.getNumberOfLines(command.offset, command.length) > 1;
  		} catch (BadLocationException e) {
  			// ignore
  			return false;
  		}
  	}
  
  	/**
  	 * Adds a space before a brace if it is inserted after a parenthesis, equal sign, or one
  	 * of the keywords <code>try, else, do</code>.
  	 *
  	 * @param doc the document we are working on
  	 * @param position the insert position of <code>character</code>
  	 * @param character the character to be inserted
  	 * @return a <code>String</code> consisting of <code>character</code> plus any additional spacing
  	 */
  	private String adjustSpacing(IDocument doc, int position, char character) {
  		if (character == BRACECHAR) {
  			if (position > 0 && position <= doc.getLength()) {
  				int pos= position - 1;
  				if (looksLike(doc, pos, ")") //$NON-NLS-1$
  				|| looksLike(doc, pos, "=") //$NON-NLS-1$
  				|| looksLike(doc, pos, "]") //$NON-NLS-1$
  				|| looksLike(doc, pos, "try") //$NON-NLS-1$
  				|| looksLike(doc, pos, "else") //$NON-NLS-1$
  				|| looksLike(doc, pos, "synchronized") //$NON-NLS-1$
  				|| looksLike(doc, pos, "static") //$NON-NLS-1$
  				|| looksLike(doc, pos, "finally") //$NON-NLS-1$
  				|| looksLike(doc, pos, "do")) //$NON-NLS-1$
  					return new String(new char[] { ' ', character });
  			}
  		}
  
  		return new String(new char[] { character });
  	}
  
  	/**
  	 * Checks whether a character to be inserted is already present at the insert location (perhaps
  	 * separated by some whitespace from <code>position</code>.
  	 *
  	 * @param document the document we are working on
  	 * @param position the insert position of <code>ch</code>
  	 * @param ch the character to be inserted
  	 * @return <code>true</code> if <code>ch</code> is already present at <code>location</code>, <code>false</code> otherwise
  	 */
  	private boolean alreadyPresent(IDocument document, char ch, int position) {
  		int pos= firstNonWhitespaceForward(document, position, fPartitioning, document.getLength());
  		try {
  			if (pos != -1 && document.getChar(pos) == ch)
  				return true;
  		} catch (BadLocationException e) {
  		}
  
  		return false;
  	}
  
  	/**
  	 * Computes the next insert position of the given character in the current line.
  	 *
  	 * @param document the document we are working on
  	 * @param line the line where the change is being made
  	 * @param offset the position of the caret in the line when <code>character</code> was typed
  	 * @param character the character to look for
  	 * @param partitioning the document partitioning
  	 * @return the position where <code>character</code> should be inserted / replaced
  	 */
  	protected static int computeCharacterPosition(IDocument document, ITextSelection line, int offset, char character, String partitioning) {
  		String text= line.getText();
  		if (text == null)
  			return 0;
  
  		int insertPos;
  		if (character == BRACECHAR) {
  
  			insertPos= computeArrayInitializationPos(document, line, offset, partitioning);
  
  			if (insertPos == -1) {
  				insertPos= computeAfterTryDoElse(document, line, offset);
  			}
  
  			if (insertPos == -1) {
  				insertPos= computeAfterParenthesis(document, line, offset, partitioning);
  			}
  
  		} else if (character == SEMICHAR) {
  
  			if (isForStatement(text, offset)) {
  				insertPos= -1; // don't do anything in for statements, as semis are vital part of these
  			} else {
  				int nextPartitionPos= nextPartitionOrLineEnd(document, line, offset, partitioning);
  				insertPos= startOfWhitespaceBeforeOffset(text, nextPartitionPos);
  				// if there is a semi present, return its location as alreadyPresent() will take it out this way.
  				if (insertPos > 0 && text.charAt(insertPos - 1) == character)
  					insertPos= insertPos - 1;
  				else if (insertPos > 0 && text.charAt(insertPos - 1) == '}') {
  					int opening= scanBackward(document, insertPos - 1 + line.getOffset(), partitioning, -1, new char[] { '{' });
  					if (opening > -1 && opening < offset + line.getOffset()) {
  						if (computeArrayInitializationPos(document, line, opening - line.getOffset(), partitioning) == -1) {
  							insertPos= offset;
  						}
  					}
  				}
  			}
  
  		} else {
  			Assert.isTrue(false);
  			return -1;
  		}
  
  		return insertPos;
  	}
  
  	/**
  	 * Computes an insert position for an opening brace if <code>offset</code> maps to a position in
  	 * <code>document</code> that looks like being the RHS of an assignment or like an array definition.
  	 *
  	 * @param document the document being modified
  	 * @param line the current line under investigation
  	 * @param offset the offset of the caret position, relative to the line start.
  	 * @param partitioning the document partitioning
  	 * @return an insert position  relative to the line start if <code>line</code> looks like being an array initialization at <code>offset</code>, -1 otherwise
  	 */
  	private static int computeArrayInitializationPos(IDocument document, ITextSelection line, int offset, String partitioning) {
  		// search backward while WS, find = (not != <= >= ==) in default partition
  		int pos= offset + line.getOffset();
  
  		if (pos == 0)
  			return -1;
  
  		int p= firstNonWhitespaceBackward(document, pos - 1, partitioning, -1);
  
  		if (p == -1)
  			return -1;
  
  		try {
  
  			char ch= document.getChar(p);
  			if (ch != '=' && ch != ']')
  				return -1;
  
  			if (p == 0)
  				return offset;
  
  			p= firstNonWhitespaceBackward(document, p - 1, partitioning, -1);
  			if (p == -1)
  				return -1;
  
  			ch= document.getChar(p);
  			if (Character.isJavaIdentifierPart(ch) || ch == ']' || ch == '[')
  				return offset;
  
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  	/**
  	 * Computes an insert position for an opening brace if <code>offset</code> maps to a position in
  	 * <code>doc</code> involving a keyword taking a block after it. These are: <code>try</code>,
  	 * <code>do</code>, <code>synchronized</code>, <code>static</code>, <code>finally</code>, or <code>else</code>.
  	 *
  	 * @param doc the document being modified
  	 * @param line the current line under investigation
  	 * @param offset the offset of the caret position, relative to the line start.
  	 * @return an insert position  relative to the line start if <code>line</code> contains one of the above keywords at or before <code>offset</code>, -1 otherwise
  	 */
  	private static int computeAfterTryDoElse(IDocument doc, ITextSelection line, int offset) {
  		// search backward while WS, find 'try', 'do', 'else' in default partition
  		int p= offset + line.getOffset();
  		p= firstWhitespaceToRight(doc, p);
  		if (p == -1)
  			return -1;
  		p--;
  
  		if (looksLike(doc, p, "try") //$NON-NLS-1$
  				|| looksLike(doc, p, "do")  //$NON-NLS-1$
  				|| looksLike(doc, p, "synchronized")  //$NON-NLS-1$
  				|| looksLike(doc, p, "static")  //$NON-NLS-1$
  				|| looksLike(doc, p, "finally")  //$NON-NLS-1$
  				|| looksLike(doc, p, "else"))  //$NON-NLS-1$
  			return p + 1 - line.getOffset();
  
  		return -1;
  	}
  
  	/**
  	 * Computes an insert position for an opening brace if <code>offset</code> maps to a position in
  	 * <code>document</code> with a expression in parenthesis that will take a block after the closing parenthesis.
  	 *
  	 * @param document the document being modified
  	 * @param line the current line under investigation
  	 * @param offset the offset of the caret position, relative to the line start.
  	 * @param partitioning the document partitioning
  	 * @return an insert position relative to the line start if <code>line</code> contains a parenthesized expression that can be followed by a block, -1 otherwise
  	 */
  	private static int computeAfterParenthesis(IDocument document, ITextSelection line, int offset, String partitioning) {
  		// find the opening parenthesis for every closing parenthesis on the current line after offset
  		// return the position behind the closing parenthesis if it looks like a method declaration
  		// or an expression for an if, while, for, catch statement
  		int pos= offset + line.getOffset();
  		int length= line.getOffset() + line.getLength();
  		int scanTo= scanForward(document, pos, partitioning, length, '}');
  		if (scanTo == -1)
  			scanTo= length;
  
  		int closingParen= findClosingParenToLeft(document, pos, partitioning) - 1;
  
  		while (true) {
  			int startScan= closingParen + 1;
  			closingParen= scanForward(document, startScan, partitioning, scanTo, ')');
  			if (closingParen == -1)
  				break;
  
  			int openingParen= findOpeningParenMatch(document, closingParen, partitioning);
  
  			// no way an expression at the beginning of the document can mean anything
  			if (openingParen < 1)
  				break;
  
  			// only select insert positions for parenthesis currently embracing the caret
  			if (openingParen > pos)
  				continue;
  
  			if (looksLikeAnonymousClassDef(document, openingParen - 1, partitioning))
  				return closingParen + 1 - line.getOffset();
  
  			if (looksLikeIfWhileForCatch(document, openingParen - 1, partitioning))
  				return closingParen + 1 - line.getOffset();
  
  			if (looksLikeMethodDecl(document, openingParen - 1, partitioning))
  				return closingParen + 1 - line.getOffset();
  
  		}
  
  		return -1;
  	}
  
  	/**
  	 * Finds a closing parenthesis to the left of <code>position</code> in document, where that parenthesis is only
  	 * separated by whitespace from <code>position</code>. If no such parenthesis can be found, <code>position</code> is returned.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @return the position of a closing parenthesis left to <code>position</code> separated only by whitespace, or <code>position</code> if no parenthesis can be found
  	 */
  	private static int findClosingParenToLeft(IDocument document, int position, String partitioning) {
  		final char CLOSING_PAREN= ')';
  		try {
  			if (position < 1)
  				return position;
  
  			int nonWS= firstNonWhitespaceBackward(document, position - 1, partitioning, -1);
  			if (nonWS != -1 && document.getChar(nonWS) == CLOSING_PAREN)
  				return nonWS;
  		} catch (BadLocationException e1) {
  		}
  		return position;
  	}
  
  	/**
  	 * Finds the first whitespace character position to the right of (and including) <code>position</code>.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @return the position of a whitespace character greater or equal than <code>position</code> separated only by whitespace, or -1 if none found
  	 */
  	private static int firstWhitespaceToRight(IDocument document, int position) {
  		int length= document.getLength();
  		Assert.isTrue(position >= 0);
  		Assert.isTrue(position <= length);
  
  		try {
  			while (position < length) {
  				char ch= document.getChar(position);
  				if (Character.isWhitespace(ch))
  					return position;
  				position++;
  			}
  			return position;
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  	/**
  	 * Finds the highest position in <code>document</code> such that the position is &lt;= <code>position</code>
  	 * and &gt; <code>bound</code> and <code>Character.isWhitespace(document.getChar(pos))</code> evaluates to <code>false</code>
  	 * and the position is in the default partition.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @param bound the first position in <code>document</code> to not consider any more, with <code>bound</code> &lt; <code>position</code>
  	 * @return the highest position of one element in <code>chars</code> in [<code>position</code>, <code>scanTo</code>) that resides in a Java partition, or <code>-1</code> if none can be found
  	 */
  	private static int firstNonWhitespaceBackward(IDocument document, int position, String partitioning, int bound) {
  		Assert.isTrue(position < document.getLength());
  		Assert.isTrue(bound >= -1);
  
  		try {
  			while (position > bound) {
  				char ch= document.getChar(position);
  				if (!Character.isWhitespace(ch) && isDefaultPartition(document, position, partitioning))
  					return position;
  				position--;
  			}
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  	/**
  	 * Finds the smallest position in <code>document</code> such that the position is &gt;= <code>position</code>
  	 * and &lt; <code>bound</code> and <code>Character.isWhitespace(document.getChar(pos))</code> evaluates to <code>false</code>
  	 * and the position is in the default partition.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @param bound the first position in <code>document</code> to not consider any more, with <code>bound</code> &gt; <code>position</code>
  	 * @return the smallest position of one element in <code>chars</code> in [<code>position</code>, <code>scanTo</code>) that resides in a Java partition, or <code>-1</code> if none can be found
  	 */
  	private static int firstNonWhitespaceForward(IDocument document, int position, String partitioning, int bound) {
  		Assert.isTrue(position >= 0);
  		Assert.isTrue(bound <= document.getLength());
  
  		try {
  			while (position < bound) {
  				char ch= document.getChar(position);
  				if (!Character.isWhitespace(ch) && isDefaultPartition(document, position, partitioning))
  					return position;
  				position++;
  			}
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  	/**
  	 * Finds the highest position in <code>document</code> such that the position is &lt;= <code>position</code>
  	 * and &gt; <code>bound</code> and <code>document.getChar(position) == ch</code> evaluates to <code>true</code> for at least one
  	 * ch in <code>chars</code> and the position is in the default partition.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @param bound the first position in <code>document</code> to not consider any more, with <code>scanTo</code> &gt; <code>position</code>
  	 * @param chars an array of <code>char</code> to search for
  	 * @return the highest position of one element in <code>chars</code> in (<code>bound</code>, <code>position</code>] that resides in a Java partition, or <code>-1</code> if none can be found
  	 */
  	private static int scanBackward(IDocument document, int position, String partitioning, int bound, char[] chars) {
  		Assert.isTrue(bound >= -1);
  		Assert.isTrue(position < document.getLength() );
  
  		Arrays.sort(chars);
  
  		try {
  			while (position > bound) {
  
  				if (Arrays.binarySearch(chars, document.getChar(position)) >= 0 && isDefaultPartition(document, position, partitioning))
  					return position;
  
  				position--;
  			}
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  //	/**
  //	 * Finds the highest position in <code>document</code> such that the position is &lt;= <code>position</code>
  //	 * and &gt; <code>bound</code> and <code>document.getChar(position) == ch</code> evaluates to <code>true</code>
  //	 * and the position is in the default partition.
  //	 *
  //	 * @param document the document being modified
  //	 * @param position the first character position in <code>document</code> to be considered
  //	 * @param bound the first position in <code>document</code> to not consider any more, with <code>scanTo</code> &gt; <code>position</code>
  //	 * @param chars an array of <code>char</code> to search for
  //	 * @return the highest position of one element in <code>chars</code> in [<code>position</code>, <code>scanTo</code>) that resides in a Java partition, or <code>-1</code> if none can be found
  //	 */
  //	private static int scanBackward(IDocument document, int position, int bound, char ch) {
  //		return scanBackward(document, position, bound, new char[] {ch});
  //	}
  //
  	/**
  	 * Finds the lowest position in <code>document</code> such that the position is &gt;= <code>position</code>
  	 * and &lt; <code>bound</code> and <code>document.getChar(position) == ch</code> evaluates to <code>true</code> for at least one
  	 * ch in <code>chars</code> and the position is in the default partition.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @param bound the first position in <code>document</code> to not consider any more, with <code>scanTo</code> &gt; <code>position</code>
  	 * @param chars an array of <code>char</code> to search for
  	 * @return the lowest position of one element in <code>chars</code> in [<code>position</code>, <code>bound</code>) that resides in a Java partition, or <code>-1</code> if none can be found
  	 */
  	private static int scanForward(IDocument document, int position, String partitioning, int bound, char[] chars) {
  		Assert.isTrue(position >= 0);
  		Assert.isTrue(bound <= document.getLength());
  
  		Arrays.sort(chars);
  
  		try {
  			while (position < bound) {
  
  				if (Arrays.binarySearch(chars, document.getChar(position)) >= 0 && isDefaultPartition(document, position, partitioning))
  					return position;
  
  				position++;
  			}
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  	/**
  	 * Finds the lowest position in <code>document</code> such that the position is &gt;= <code>position</code>
  	 * and &lt; <code>bound</code> and <code>document.getChar(position) == ch</code> evaluates to <code>true</code>
  	 * and the position is in the default partition.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @param bound the first position in <code>document</code> to not consider any more, with <code>scanTo</code> &gt; <code>position</code>
  	 * @param ch a <code>char</code> to search for
  	 * @return the lowest position of one element in <code>chars</code> in [<code>position</code>, <code>bound</code>) that resides in a Java partition, or <code>-1</code> if none can be found
  	 */
  	private static int scanForward(IDocument document, int position, String partitioning, int bound, char ch) {
  		return scanForward(document, position, partitioning, bound, new char[] {ch});
  	}
  
  	/**
  	 * Checks whether the content of <code>document</code> in the range (<code>offset</code>, <code>length</code>)
  	 * contains the <code>new</code> keyword.
  	 *
  	 * @param document the document being modified
  	 * @param offset the first character position in <code>document</code> to be considered
  	 * @param length the length of the character range to be considered
  	 * @param partitioning the document partitioning
  	 * @return <code>true</code> if the specified character range contains a <code>new</code> keyword, <code>false</code> otherwise.
  	 */
  	private static boolean isNewMatch(IDocument document, int offset, int length, String partitioning) {
  		Assert.isTrue(length >= 0);
  		Assert.isTrue(offset >= 0);
  		Assert.isTrue(offset + length < document.getLength() + 1);
  
  		try {
  			String text= document.get(offset, length);
  			int pos= text.indexOf("new"); //$NON-NLS-1$
  
  			while (pos != -1 && !isDefaultPartition(document, pos + offset, partitioning))
  				pos= text.indexOf("new", pos + 2); //$NON-NLS-1$
  
  			if (pos < 0)
  				return false;
  
  			if (pos != 0 && Character.isJavaIdentifierPart(text.charAt(pos - 1)))
  				return false;
  
  			if (pos + 3 < length && Character.isJavaIdentifierPart(text.charAt(pos + 3)))
  				return false;
  
  			return true;
  
  		} catch (BadLocationException e) {
  		}
  		return false;
  	}
  
  	/**
  	 * Checks whether the content of <code>document</code> at <code>position</code> looks like an
  	 * anonymous class definition. <code>position</code> must be to the left of the opening
  	 * parenthesis of the definition's parameter list.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @return <code>true</code> if the content of <code>document</code> looks like an anonymous class definition, <code>false</code> otherwise
  	 */
  	private static boolean looksLikeAnonymousClassDef(IDocument document, int position, String partitioning) {
  		int previousCommaParenEqual= scanBackward(document, position - 1, partitioning, -1, new char[] {',', '(', '='});
  		if (previousCommaParenEqual == -1 || position < previousCommaParenEqual + 5) // 2 for borders, 3 for "new"
  			return false;
  
  		if (isNewMatch(document, previousCommaParenEqual + 1, position - previousCommaParenEqual - 2, partitioning))
  			return true;
  
  		return false;
  	}
  
  	/**
  	 * Checks whether <code>position</code> resides in a default (Java) partition of <code>document</code>.
  	 *
  	 * @param document the document being modified
  	 * @param position the position to be checked
  	 * @param partitioning the document partitioning
  	 * @return <code>true</code> if <code>position</code> is in the default partition of <code>document</code>, <code>false</code> otherwise
  	 */
  	private static boolean isDefaultPartition(IDocument document, int position, String partitioning) {
  		Assert.isTrue(position >= 0);
  		Assert.isTrue(position <= document.getLength());
  
  		try {
  			// don't use getPartition2 since we're interested in the scanned character's partition
  			ITypedRegion region= TextUtilities.getPartition(document, partitioning, position, false);
  			return region.getType().equals(IDocument.DEFAULT_CONTENT_TYPE);
  
  		} catch (BadLocationException e) {
  		}
  
  		return false;
  	}
  
  	/**
  	 * Finds the position of the parenthesis matching the closing parenthesis at <code>position</code>.
  	 *
  	 * @param document the document being modified
  	 * @param position the position in <code>document</code> of a closing parenthesis
  	 * @param partitioning the document partitioning
  	 * @return the position in <code>document</code> of the matching parenthesis, or -1 if none can be found
  	 */
  	private static int findOpeningParenMatch(IDocument document, int position, String partitioning) {
  		final char CLOSING_PAREN= ')';
  		final char OPENING_PAREN= '(';
  
  		Assert.isTrue(position < document.getLength());
  		Assert.isTrue(position >= 0);
  		Assert.isTrue(isDefaultPartition(document, position, partitioning));
  
  		try {
  
  			Assert.isTrue(document.getChar(position) == CLOSING_PAREN);
  
  			int depth= 1;
  			while (true) {
  				position= scanBackward(document, position - 1, partitioning, -1, new char[] {CLOSING_PAREN, OPENING_PAREN});
  				if (position == -1)
  					return -1;
  
  				if (document.getChar(position) == CLOSING_PAREN)
  					depth++;
  				else
  					depth--;
  
  				if (depth == 0)
  					return position;
  			}
  
  		} catch (BadLocationException e) {
  			return -1;
  		}
  	}
  
  	/**
  	 * Checks whether, to the left of <code>position</code> and separated only by whitespace,
  	 * <code>document</code> contains a keyword taking a parameter list and a block after it.
  	 * These are: <code>if</code>, <code>while</code>, <code>catch</code>, <code>for</code>, <code>synchronized</code>, <code>switch</code>.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @return <code>true</code> if <code>document</code> contains any of the above keywords to the left of <code>position</code>, <code>false</code> otherwise
  	 */
  	private static boolean looksLikeIfWhileForCatch(IDocument document, int position, String partitioning) {
  		position= firstNonWhitespaceBackward(document, position, partitioning, -1);
  		if (position == -1)
  			return false;
  
  		return looksLike(document, position, "if") //$NON-NLS-1$
  				|| looksLike(document, position, "while") //$NON-NLS-1$
  				|| looksLike(document, position, "catch") //$NON-NLS-1$
  				|| looksLike(document, position, "synchronized") //$NON-NLS-1$
  				|| looksLike(document, position, "switch") //$NON-NLS-1$
  				|| looksLike(document, position, "for"); //$NON-NLS-1$
  	}
  
  	/**
  	 * Checks whether code>document</code> contains the <code>String</code> <code>like</code> such
  	 * that its last character is at <code>position</code>. If <code>like</code> starts with a
  	 * identifier part (as determined by {@link Character#isJavaIdentifierPart(char)}), it is also made
  	 * sure that <code>like</code> is preceded by some non-identifier character or stands at the
  	 * document start.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param like the <code>String</code> to look for.
  	 * @return <code>true</code> if  <code>document</code> contains <code>like</code> such that it ends at <code>position</code>, <code>false</code> otherwise
  	 */
  	private static boolean looksLike(IDocument document, int position, String like) {
  		int length= like.length();
  		if (position < length - 1)
  			return false;
  
  		try {
  			if (!like.equals(document.get(position - length + 1, length)))
  				return false;
  
  			if (position >= length && Character.isJavaIdentifierPart(like.charAt(0)) && Character.isJavaIdentifierPart(document.getChar(position - length)))
  				return false;
  
  		} catch (BadLocationException e) {
  			return false;
  		}
  
  		return true;
  	}
  
  	/**
  	 * Checks whether the content of <code>document</code> at <code>position</code> looks like a
  	 * method declaration header (i.e. only the return type and method name). <code>position</code>
  	 * must be just left of the opening parenthesis of the parameter list.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @return <code>true</code> if the content of <code>document</code> looks like a method definition, <code>false</code> otherwise
  	 */
  	private static boolean looksLikeMethodDecl(IDocument document, int position, String partitioning) {
  
  		// method name
  		position= eatIdentToLeft(document, position, partitioning);
  		if (position < 1)
  			return false;
  
  		position= eatBrackets(document, position - 1, partitioning);
  		if (position < 1)
  			return false;
  
  		position= eatIdentToLeft(document, position - 1, partitioning);
  
  		return position != -1;
  	}
  
  	/**
  	 * From <code>position</code> to the left, eats any whitespace and then a pair of brackets
  	 * as used to declare an array return type like <pre>String [ ]</pre>.
  	 * The return value is either the position of the opening bracket or <code>position</code> if no
  	 * pair of brackets can be parsed.
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @return the smallest character position of bracket pair or <code>position</code>
  	 */
  	private static int eatBrackets(IDocument document, int position, String partitioning) {
  		// accept array return type
  		int pos= firstNonWhitespaceBackward(document, position, partitioning, -1);
  		try {
  			if (pos > 1 && document.getChar(pos) == ']') {
  				pos= firstNonWhitespaceBackward(document, pos - 1, partitioning, -1);
  				if (pos > 0 && document.getChar(pos) == '[')
  					return pos;
  			}
  		} catch (BadLocationException e) {
  			// won't happen
  		}
  		return position;
  	}
  
  	/**
  	 * From <code>position</code> to the left, eats any whitespace and the first identifier, returning
  	 * the position of the first identifier character (in normal read order).
  	 * <p>When called on a document with content <code>" some string  "</code> and positionition 13, the
  	 * return value will be 6 (the first letter in <code>string</code>).
  	 * </p>
  	 *
  	 * @param document the document being modified
  	 * @param position the first character position in <code>document</code> to be considered
  	 * @param partitioning the document partitioning
  	 * @return the smallest character position of an identifier or -1 if none can be found; always &lt;= <code>position</code>
  	 */
  	private static int eatIdentToLeft(IDocument document, int position, String partitioning) {
  		if (position < 0)
  			return -1;
  		Assert.isTrue(position < document.getLength());
  
  		int p= firstNonWhitespaceBackward(document, position, partitioning, -1);
  		if (p == -1)
  			return -1;
  
  		try {
  			while (p >= 0) {
  
  				char ch= document.getChar(p);
  				if (Character.isJavaIdentifierPart(ch)) {
  					p--;
  					continue;
  				}
  
  				// length must be > 0
  				if (Character.isWhitespace(ch) && p != position)
  					return p + 1;
  				else
  					return -1;
  
  			}
  
  			// start of document reached
  			return 0;
  
  		} catch (BadLocationException e) {
  		}
  		return -1;
  	}
  
  	/**
  	 * Returns a position in the first java partition after the last non-empty and non-comment partition.
  	 * There is no non-whitespace from the returned position to the end of the partition it is contained in.
  	 *
  	 * @param document the document being modified
  	 * @param line the line under investigation
  	 * @param offset the caret offset into <code>line</code>
  	 * @param partitioning the document partitioning
  	 * @return the position of the next Java partition, or the end of <code>line</code>
  	 */
  	private static int nextPartitionOrLineEnd(IDocument document, ITextSelection line, int offset, String partitioning) {
  		// run relative to document
  		final int docOffset= offset + line.getOffset();
  		final int eol= line.getOffset() + line.getLength();
  		int nextPartitionPos= eol; // init with line end
  		int validPosition= docOffset;
  
  		try {
  			ITypedRegion partition= TextUtilities.getPartition(document, partitioning, nextPartitionPos, true);
  			validPosition= getValidPositionForPartition(document, partition, eol);
  			while (validPosition == -1) {
  				nextPartitionPos= partition.getOffset() - 1;
  				if (nextPartitionPos < docOffset) {
  					validPosition= docOffset;
  					break;
  				}
  				partition= TextUtilities.getPartition(document, partitioning, nextPartitionPos, false);
  				validPosition= getValidPositionForPartition(document, partition, eol);
  			}
  		} catch (BadLocationException e) {
  		}
  
  		validPosition= Math.max(validPosition, docOffset);
  		// make relative to line
  		validPosition -= line.getOffset();
  		return validPosition;
  	}
  
  	/**
  	 * Returns a valid insert location (except for whitespace) in <code>partition</code> or -1 if
  	 * there is no valid insert location.
  	 * An valid insert location is right after any java string or character partition, or at the end
  	 * of a java default partition, but never behind <code>maxOffset</code>. Comment partitions or
  	 * empty java partitions do never yield valid insert positions.
  	 *
  	 * @param doc the document being modified
  	 * @param partition the current partition
  	 * @param maxOffset the maximum offset to consider
  	 * @return a valid insert location in <code>partition</code>, or -1 if there is no valid insert location
  	 */
  	private static int getValidPositionForPartition(IDocument doc, ITypedRegion partition, int maxOffset) {
  		final int INVALID= -1;
  
  		if (IJavaScriptPartitions.JAVA_DOC.equals(partition.getType()))
  			return INVALID;
  		if (IJavaScriptPartitions.JAVA_MULTI_LINE_COMMENT.equals(partition.getType()))
  			return INVALID;
  		if (IJavaScriptPartitions.JAVA_SINGLE_LINE_COMMENT.equals(partition.getType()))
  			return INVALID;
  
  		int endOffset= Math.min(maxOffset, partition.getOffset() + partition.getLength());
  
  		if (IJavaScriptPartitions.JAVA_CHARACTER.equals(partition.getType()))
  			return endOffset;
  		if (IJavaScriptPartitions.JAVA_STRING.equals(partition.getType()))
  			return endOffset;
  		if (IDocument.DEFAULT_CONTENT_TYPE.equals(partition.getType())) {
  			try {
  				if (doc.get(partition.getOffset(), endOffset - partition.getOffset()).trim().length() == 0)
  					return INVALID;
  				else
  					return endOffset;
  			} catch (BadLocationException e) {
  				return INVALID;
  			}
  		}
  		// default: we don't know anything about the partition - assume valid
  		return endOffset;
  	}
  
  	/**
  	 * Determines whether the current line contains a for statement.
  	 * Algorithm: any "for" word in the line is a positive, "for" contained in a string literal will
  	 * produce a false positive.
  	 *
  	 * @param line the line where the change is being made
  	 * @param offset the position of the caret
  	 * @return <code>true</code> if <code>line</code> contains <code>for</code>, <code>false</code> otherwise
  	 */
  	private static boolean isForStatement(String line, int offset) {
  		/* searching for (^|\s)for(\s|$) */
  		int forPos= line.indexOf("for"); //$NON-NLS-1$
  		if (forPos != -1) {
  			if ((forPos == 0 || !Character.isJavaIdentifierPart(line.charAt(forPos - 1))) && (line.length() == forPos + 3 || !Character.isJavaIdentifierPart(line.charAt(forPos + 3))))
  				return true;
  		}
  		return false;
  	}
  
  	/**
  	 * Returns the position in <code>text</code> after which there comes only whitespace, up to
  	 * <code>offset</code>.
  	 *
  	 * @param text the text being searched
  	 * @param offset the maximum offset to search for
  	 * @return the smallest value <code>v</code> such that <code>text.substring(v, offset).trim() == 0</code>
  	 */
  	private static int startOfWhitespaceBeforeOffset(String text, int offset) {
  		int i= Math.min(offset, text.length());
  		for (; i >= 1; i--) {
  			if (!Character.isWhitespace(text.charAt(i - 1)))
  				break;
  		}
  		return i;
  	}
  }
  