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// Copyright 2007 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview DOM pattern to match a sequence of other patterns.
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 *
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 * @author [email protected] (Robby Walker)
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 */
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goog.provide('goog.dom.pattern.Sequence');
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goog.require('goog.dom.NodeType');
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goog.require('goog.dom.pattern');
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goog.require('goog.dom.pattern.AbstractPattern');
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goog.require('goog.dom.pattern.MatchType');
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/**
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 * Pattern object that matches a sequence of other patterns.
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 *
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 * @param {Array<goog.dom.pattern.AbstractPattern>} patterns Ordered array of
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 *     patterns to match.
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 * @param {boolean=} opt_ignoreWhitespace Optional flag to ignore text nodes
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 *     consisting entirely of whitespace.  The default is to not ignore them.
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 * @constructor
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 * @extends {goog.dom.pattern.AbstractPattern}
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 * @final
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 */
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goog.dom.pattern.Sequence = function(patterns, opt_ignoreWhitespace) {
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  /**
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   * Ordered array of patterns to match.
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   *
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   * @type {Array<goog.dom.pattern.AbstractPattern>}
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   */
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  this.patterns = patterns;
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  /**
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   * Whether or not to ignore whitespace only Text nodes.
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   *
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   * @private {boolean}
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   */
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  this.ignoreWhitespace_ = !!opt_ignoreWhitespace;
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  /**
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   * Position in the patterns array we have reached by successful matches.
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   *
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   * @private {number}
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   */
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  this.currentPosition_ = 0;
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};
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goog.inherits(goog.dom.pattern.Sequence, goog.dom.pattern.AbstractPattern);
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/**
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 * Regular expression for breaking text nodes.
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 * @private {!RegExp}
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 */
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goog.dom.pattern.Sequence.BREAKING_TEXTNODE_RE_ = /^\s*$/;
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/**
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 * Test whether the given token starts, continues, or finishes the sequence
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 * of patterns given in the constructor.
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 *
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 * @param {Node} token Token to match against.
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 * @param {goog.dom.TagWalkType} type The type of token.
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 * @return {goog.dom.pattern.MatchType} <code>MATCH</code> if the pattern
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 *     matches, <code>MATCHING</code> if the pattern starts a match, and
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 *     <code>NO_MATCH</code> if the pattern does not match.
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 * @override
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 */
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goog.dom.pattern.Sequence.prototype.matchToken = function(token, type) {
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  // If the option is set, ignore any whitespace only text nodes
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  if (this.ignoreWhitespace_ && token.nodeType == goog.dom.NodeType.TEXT &&
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      goog.dom.pattern.Sequence.BREAKING_TEXTNODE_RE_.test(token.nodeValue)) {
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    return goog.dom.pattern.MatchType.MATCHING;
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  }
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  switch (this.patterns[this.currentPosition_].matchToken(token, type)) {
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    case goog.dom.pattern.MatchType.MATCH:
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      // Record the first token we match.
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      if (this.currentPosition_ == 0) {
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        this.matchedNode = token;
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      }
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      // Move forward one position.
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      this.currentPosition_++;
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      // Check if this is the last position.
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      if (this.currentPosition_ == this.patterns.length) {
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        this.reset();
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        return goog.dom.pattern.MatchType.MATCH;
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      } else {
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        return goog.dom.pattern.MatchType.MATCHING;
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      }
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    case goog.dom.pattern.MatchType.MATCHING:
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      // This can happen when our child pattern is a sequence or a repetition.
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      return goog.dom.pattern.MatchType.MATCHING;
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    case goog.dom.pattern.MatchType.BACKTRACK_MATCH:
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      // This means a repetitive match succeeded 1 token ago.
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      // TODO(robbyw): Backtrack further if necessary.
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      this.currentPosition_++;
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      if (this.currentPosition_ == this.patterns.length) {
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        this.reset();
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        return goog.dom.pattern.MatchType.BACKTRACK_MATCH;
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      } else {
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        // Retry the same token on the next pattern.
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        return this.matchToken(token, type);
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      }
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    default:
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      this.reset();
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      return goog.dom.pattern.MatchType.NO_MATCH;
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  }
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};
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/**
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 * Reset any internal state this pattern keeps.
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 * @override
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 */
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goog.dom.pattern.Sequence.prototype.reset = function() {
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  if (this.patterns[this.currentPosition_]) {
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    this.patterns[this.currentPosition_].reset();
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  }
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  this.currentPosition_ = 0;
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};
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