content: /*******************************************************************************
   * Copyright (c) 2000, 2007 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.ArrayList;
  import java.util.List;
  
  import org.eclipse.core.runtime.Assert;
  import org.eclipse.jface.text.BadLocationException;
  import org.eclipse.jface.text.IDocument;
  import org.eclipse.jface.text.IRegion;
  import org.eclipse.jface.text.ITextViewer;
  import org.eclipse.jface.text.TextPresentation;
  import org.eclipse.jface.text.contentassist.IContextInformation;
  import org.eclipse.jface.text.contentassist.IContextInformationPresenter;
  import org.eclipse.jface.text.contentassist.IContextInformationValidator;
  import org.eclipse.swt.SWT;
  import org.eclipse.swt.custom.StyleRange;
  import org.eclipse.wst.jsdt.internal.ui.text.JavaHeuristicScanner;
  
  
  
  public class JavaParameterListValidator implements IContextInformationValidator, IContextInformationPresenter {
  
  	private int fPosition;
  	private ITextViewer fViewer;
  	private IContextInformation fInformation;
  
  	private int fCurrentParameter;
  
  
  
  	public JavaParameterListValidator() {
  	}
  
  	/**
  	 * @see IContextInformationValidator#install(IContextInformation, ITextViewer, int)
  	 * @see IContextInformationPresenter#install(IContextInformation, ITextViewer, int)
  	 */
  	public void install(IContextInformation info, ITextViewer viewer, int documentPosition) {
  		fPosition= documentPosition;
  		fViewer= viewer;
  		fInformation= info;
  
  		fCurrentParameter= -1;
  	}
  
  	private int getCommentEnd(IDocument d, int pos, int end) throws BadLocationException {
  		while (pos < end) {
  			char curr= d.getChar(pos);
  			pos++;
  			if (curr == '*') {
  				if (pos < end && d.getChar(pos) == '/') {
  					return pos + 1;
  				}
  			}
  		}
  		return end;
  	}
  
  	private int getStringEnd(IDocument d, int pos, int end, char ch) throws BadLocationException {
  		while (pos < end) {
  			char curr= d.getChar(pos);
  			pos++;
  			if (curr == '\\') {
  				// ignore escaped characters
  				pos++;
  			} else if (curr == ch) {
  				return pos;
  			}
  		}
  		return end;
  	}
  
  	private int getCharCount(IDocument document, final int start, final int end, String increments, String decrements, boolean considerNesting) throws BadLocationException {
  
  		Assert.isTrue((increments.length() != 0 || decrements.length() != 0) && !increments.equals(decrements));
  		
  		final int NONE= 0;
  		final int BRACKET= 1;
  		final int BRACE= 2;
  		final int PAREN= 3;
  		final int ANGLE= 4;
  
  		int nestingMode= NONE;
  		int nestingLevel= 0;
  
  		int charCount= 0;
  		int offset= start;
  		while (offset < end) {
  			char curr= document.getChar(offset++);
  			switch (curr) {
  				case '/':
  					if (offset < end) {
  						char next= document.getChar(offset);
  						if (next == '*') {
  							// a comment starts, advance to the comment end
  							offset= getCommentEnd(document, offset + 1, end);
  						} else if (next == '/') {
  							// '//'-comment: nothing to do anymore on this line
  							offset= end;
  						}
  					}
  					break;
  				case '*':
  					if (offset < end) {
  						char next= document.getChar(offset);
  						if (next == '/') {
  							// we have been in a comment: forget what we read before
  							charCount= 0;
  							++ offset;
  						}
  					}
  					break;
  				case '"':
  				case '\'':
  					offset= getStringEnd(document, offset, end, curr);
  					break;
  				case '[':
  					if (considerNesting) {
  						if (nestingMode == BRACKET || nestingMode == NONE) {
  							nestingMode= BRACKET;
  							nestingLevel++;
  						}
  						break;
  					}
  				case ']':
  					if (considerNesting) {
  						if (nestingMode == BRACKET)
  							if (--nestingLevel == 0)
  								nestingMode= NONE;
  						break;
  					}
  				case '(':
  					if (considerNesting) {
  						if (nestingMode == ANGLE) {
  							// generics heuristic failed
  							nestingMode=PAREN;
  							nestingLevel= 1;
  						}
  						if (nestingMode == PAREN || nestingMode == NONE) {
  							nestingMode= PAREN;
  							nestingLevel++;
  						}
  						break;
  					}
  				case ')':
  					if (considerNesting) {
  						if (nestingMode == PAREN)
  							if (--nestingLevel == 0)
  								nestingMode= NONE;
  						break;
  					}
  				case '{':
  					if (considerNesting) {
  						if (nestingMode == ANGLE) {
  							// generics heuristic failed
  							nestingMode=BRACE;
  							nestingLevel= 1;
  						}
  						if (nestingMode == BRACE || nestingMode == NONE) {
  							nestingMode= BRACE;
  							nestingLevel++;
  						}
  						break;
  					}
  				case '}':
  					if (considerNesting) {
  						if (nestingMode == BRACE)
  							if (--nestingLevel == 0)
  								nestingMode= NONE;
  						break;
  					}
  				case '<':
  					if (considerNesting) {
  						if (nestingMode == ANGLE || nestingMode == NONE && checkGenericsHeuristic(document, offset - 1, start - 1)) {
  							nestingMode= ANGLE;
  							nestingLevel++;
  						}
  						break;
  					}
  				case '>':
  					if (considerNesting) {
  						if (nestingMode == ANGLE)
  							if (--nestingLevel == 0)
  								nestingMode= NONE;
  						break;
  					}
  
  				default:
  					if (nestingLevel != 0)
  						continue;
  
  					if (increments.indexOf(curr) >= 0) {
  						++ charCount;
  					}
  
  					if (decrements.indexOf(curr) >= 0) {
  						-- charCount;
  					}
  			}
  		}
  
  		return charCount;
  	}
  
      private boolean checkGenericsHeuristic(IDocument document, int end, int bound) throws BadLocationException {
      	JavaHeuristicScanner scanner= new JavaHeuristicScanner(document);
      	return scanner.looksLikeClassInstanceCreationBackward(end, bound);
      }
  
  	/**
  	 * @see IContextInformationValidator#isContextInformationValid(int)
  	 */
  	public boolean isContextInformationValid(int position) {
  
  		try {
  			if (position < fPosition)
  				return false;
  
  			IDocument document= fViewer.getDocument();
  			IRegion line= document.getLineInformationOfOffset(fPosition);
  
  			if (position < line.getOffset() || position >= document.getLength())
  				return false;
  
  			return getCharCount(document, fPosition, position, "(<", ")>", false) >= 0; //$NON-NLS-1$ //$NON-NLS-2$
  
  		} catch (BadLocationException x) {
  			return false;
  		}
  	}
  
  	/**
  	 * @see IContextInformationPresenter#updatePresentation(int, TextPresentation)
  	 */
  	public boolean updatePresentation(int position, TextPresentation presentation) {
  
  		int currentParameter= -1;
  
  		try {
  			currentParameter= getCharCount(fViewer.getDocument(), fPosition, position, ",", "", true);  //$NON-NLS-1$//$NON-NLS-2$
  		} catch (BadLocationException x) {
  			return false;
  		}
  
  		if (fCurrentParameter != -1) {
  			if (currentParameter == fCurrentParameter)
  				return false;
  		}
  
  		presentation.clear();
  		fCurrentParameter= currentParameter;
  
  		String s= fInformation.getInformationDisplayString();
  		int[] commas= computeCommaPositions(s);
  
  		if (commas.length - 2 < fCurrentParameter) {
  			presentation.addStyleRange(new StyleRange(0, s.length(), null, null, SWT.NORMAL));
  			return true;
  		}
  		
  		int start= commas[fCurrentParameter] + 1;
  		int end= commas[fCurrentParameter + 1];
  		if (start > 0)
  			presentation.addStyleRange(new StyleRange(0, start, null, null, SWT.NORMAL));
  
  		if (end > start)
  			presentation.addStyleRange(new StyleRange(start, end - start, null, null, SWT.BOLD));
  
  		if (end < s.length())
  			presentation.addStyleRange(new StyleRange(end, s.length() - end, null, null, SWT.NORMAL));
  
  		return true;
  	}
  	
  	private int[] computeCommaPositions(String code) {
  		final int length= code.length();
  	    int pos= 0;
  		List positions= new ArrayList();
  		positions.add(Integer.valueOf(-1));
  		while (pos < length && pos != -1) {
  			char ch= code.charAt(pos);
  			switch (ch) {
  	            case ',':
  		            positions.add(Integer.valueOf(pos));
  		            break;
  	            case '<':
  	            	pos= code.indexOf('>', pos);
  	            	break;
  	            case '[':
  	            	pos= code.indexOf(']', pos);
  	            	break;
  	            default:
  	            	break;
              }
  			if (pos != -1)
  				pos++;
  		}
  		positions.add(Integer.valueOf(length));
  		
  		int[] fields= new int[positions.size()];
  		for (int i= 0; i < fields.length; i++)
  	        fields[i]= ((Integer) positions.get(i)).intValue();
  	    return fields;
      }
  
  }
  
  