1  /*
     2   * Copyright the original author or authors.
     3   * 
     4   * Licensed under the MOZILLA PUBLIC LICENSE, Version 1.1 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   * 
     8   *      http://www.mozilla.org/MPL/MPL-1.1.html
     9   * 
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16   
    17  import org.as2lib.regexp.node.Node; 
    18  import org.as2lib.regexp.node.TreeInfo;
    19  
    20  /**
    21   * {@code BackRef} refers to a group in the regular expression. 
    22   * Attempts to match whatever the group referred to last matched.
    23   * 
    24   * @author Igor Sadovskiy
    25   */
    26   
    27  class org.as2lib.regexp.node.BackRef extends Node {
    28  	
    29      private var groupIndex:Number;
    30      
    31      public function BackRef(groupCount:Number) {
    32          super();
    33          groupIndex = groupCount + groupCount;
    34      }
    35      
    36      public function match(matcher:Object, i:Number, seq:String):Boolean {
    37          var j:Number = matcher.groups[groupIndex];
    38          var k:Number = matcher.groups[groupIndex+1];
    39  
    40          var groupSize:Number = k - j;
    41  
    42          // If the referenced group didn't match, neither can this
    43          if (j < 0) return false;
    44  
    45          // If there isn't enough input left no match
    46          if (i + groupSize > matcher.to) return false;
    47  
    48          // Check each new char to make sure it matches what the group
    49          // referenced matched last time around
    50          for (var index=0; index<groupSize; index++) {
    51              if (seq.charAt(i+index) != seq.charAt(j+index)) {
    52                  return false;
    53              }
    54          }
    55  
    56          return next.match(matcher, i+groupSize, seq);
    57      }
    58      
    59      public function study(info:TreeInfo):Boolean {
    60          info.maxValid = false;
    61          return next.study(info);
    62      }
    63  }
    64  
    65
as2api