QuestionPrevLineStartsWith.java :  » IDE » DrJava » edu » rice » cs » drjava » model » definitions » indent » Java Open Source

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package edu.rice.cs.drjava.model.definitions.indent;

import javax.swing.text.*;
import edu.rice.cs.util.UnexpectedException;

import edu.rice.cs.drjava.model.AbstractDJDocument;

/** Question rule in indentation decision tree.  Determines if the preceding line starts with the specified character.
  * @version $Id: QuestionPrevLineStartsWith.java 5175 2010-01-20 08:46:32Z mgricken $
  */
public class QuestionPrevLineStartsWith extends IndentRuleQuestion {
  private String _prefix;
  
  /** Constructs a new rule for the given prefix string.  ALWAYS looks inside comments.  Only runs in the event thread.
    * @param prefix String to search for
    * @param yesRule Rule to use if this rule holds
    * @param noRule Rule to use if this rule does not hold
    */
  public QuestionPrevLineStartsWith(String prefix, IndentRule yesRule, IndentRule noRule) {
    super(yesRule, noRule);
    _prefix = prefix;
  }
  
  /** Determines if the previous line in the document starts with the specified characters, ignoring whitespace.
    * @param doc AbstractDJDocument containing the line to be indented.
    * @return true if this node's rule holds.
    */
  boolean applyRule(AbstractDJDocument doc, Indenter.IndentReason reason) {

    try {
      // Find start of line
      int here = doc.getCurrentLocation();
      int startLine = doc._getLineStartPos(here);
      
      if (startLine > 0) {
        // Find start of previous line
        int startPrevLine = doc._getLineStartPos(startLine - 1);
        int firstChar = doc._getLineFirstCharPos(startPrevLine);
        
        // Compare prefix
        String actualPrefix = doc.getText(firstChar, _prefix.length());
        return _prefix.equals(actualPrefix);
      }
    }
    catch (BadLocationException e) {
      // Shouldn't happen
      throw new UnexpectedException(e);
    }
    // On first line
    return false;
  }

}