PropertyParser.java

package org.ant4eclipse.lib.platform.internal.model.resource.variable;

import java.util.Vector;

/**
 * A class that is able to parse properties in Strings like <code>${project_loc}</echo>
 * 
 * @author nils
 * 
 */
public class PropertyParser {

  /**
   * based on org.apache.tools.ant.PropertyHelper#parsePropertyString
   */
  public final void parsePropertyString(String value, Vector<String> fragments, Vector<String> propertyRefs,
      Vector<String> propertyArgs) {
    int prev = 0;
    int pos;
    // search for the next instance of $ from the 'prev' position
    while ((pos = value.indexOf("$", prev)) >= 0) {

      // if there was any text before this, add it as a fragment
      // TODO, this check could be modified to go if pos>prev;
      // seems like this current version could stick empty strings
      // into the list
      if (pos > 0) {
        fragments.addElement(value.substring(prev, pos));
      }
      // if we are at the end of the string, we tack on a $
      // then move past it
      if (pos == (value.length() - 1)) {
        fragments.addElement("$");
        prev = pos + 1;
      } else if (value.charAt(pos + 1) != '{') {
        // peek ahead to see if the next char is a property or not
        // not a property: insert the char as a literal
        /*
         * fragments.addElement(value.substring(pos + 1, pos + 2)); prev = pos + 2;
         */
        if (value.charAt(pos + 1) == '$') {
          // backwards compatibility two $ map to one mode
          fragments.addElement("$");
          prev = pos + 2;
        } else {
          // new behaviour: $X maps to $X for all values of X!='$'
          fragments.addElement(value.substring(pos, pos + 2));
          prev = pos + 2;
        }

      } else {
        // property found, extract its name or bail on a typo
        int endName = value.indexOf('}', pos);
        if (endName < 0) {
          throw new RuntimeException("Syntax error in property: " + value);
        }
        String propertyName = value.substring(pos + 2, endName);
        // cut off eclipse arguments, since they are not supported
        // by ant4eclipse
        int v = propertyName.indexOf(':');
        String propertyArg = null;
        if (v != -1) {
          propertyArg = propertyName.substring(v + 1);
          propertyName = propertyName.substring(0, v);
        }
        fragments.addElement(null);
        propertyRefs.addElement(propertyName);
        propertyArgs.addElement(propertyArg);
        prev = endName + 1;
      }
    }
    // no more $ signs found
    // if there is any tail to the file, append it
    if (prev < value.length()) {
      fragments.addElement(value.substring(prev));
    }
  }

}