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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 any children of a tag, and
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 * specifically collect those that match a child pattern.
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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.ChildMatches');
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goog.require('goog.dom.pattern.AllChildren');
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goog.require('goog.dom.pattern.MatchType');
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/**
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 * Pattern object that matches any nodes at or below the current tree depth.
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 *
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 * @param {goog.dom.pattern.AbstractPattern} childPattern Pattern to collect
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 *     child matches of.
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 * @param {number=} opt_minimumMatches Enforce a minimum nuber of matches.
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 *     Defaults to 0.
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 * @constructor
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 * @extends {goog.dom.pattern.AllChildren}
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 * @final
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 */
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goog.dom.pattern.ChildMatches = function(childPattern, opt_minimumMatches) {
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  /**
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   * The child pattern to collect matches from.
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   *
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   * @private {goog.dom.pattern.AbstractPattern}
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   */
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  this.childPattern_ = childPattern;
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  /**
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   * Array of matched child nodes.
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   *
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   * @type {Array<Node>}
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   */
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  this.matches = [];
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  /**
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   * Minimum number of matches.
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   *
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   * @private {number}
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   */
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  this.minimumMatches_ = opt_minimumMatches || 0;
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  /**
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   * Whether the pattern has recently matched or failed to match and will need
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   * to be reset when starting a new round of matches.
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   *
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   * @private {boolean}
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   */
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  this.needsReset_ = false;
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  goog.dom.pattern.ChildMatches.base(this, 'constructor');
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};
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goog.inherits(goog.dom.pattern.ChildMatches, goog.dom.pattern.AllChildren);
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/**
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 * Test whether the given token is on the same level.
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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 MATCHING} if the token is on the
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 *     same level or deeper and {@code BACKTRACK_MATCH} if not.
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 * @override
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 */
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goog.dom.pattern.ChildMatches.prototype.matchToken = function(token, type) {
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  // Defer resets so we maintain our matches array until the last possible time.
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  if (this.needsReset_) {
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    this.reset();
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  }
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  // Call the super-method to ensure we stay in the child tree.
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  var status =
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      goog.dom.pattern.AllChildren.prototype.matchToken.apply(this, arguments);
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  switch (status) {
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    case goog.dom.pattern.MatchType.MATCHING:
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      var backtrack = false;
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      switch (this.childPattern_.matchToken(token, type)) {
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        case goog.dom.pattern.MatchType.BACKTRACK_MATCH:
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          backtrack = true;
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        case goog.dom.pattern.MatchType.MATCH:
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          // Collect the match.
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          this.matches.push(this.childPattern_.matchedNode);
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          break;
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        default:
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          // Keep trying if we haven't hit a terminal state.
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          break;
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      }
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      if (backtrack) {
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        // The only interesting result is a MATCH, since BACKTRACK_MATCH means
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        // we are hitting an infinite loop on something like a Repeat(0).
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        if (this.childPattern_.matchToken(token, type) ==
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            goog.dom.pattern.MatchType.MATCH) {
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          this.matches.push(this.childPattern_.matchedNode);
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        }
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      }
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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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      // TODO(robbyw): this should return something like BACKTRACK_NO_MATCH
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      // when we don't meet our minimum.
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      this.needsReset_ = true;
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      return (this.matches.length >= this.minimumMatches_) ?
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          goog.dom.pattern.MatchType.BACKTRACK_MATCH :
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          goog.dom.pattern.MatchType.NO_MATCH;
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    default:
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      this.needsReset_ = true;
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      return status;
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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.ChildMatches.prototype.reset = function() {
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  this.needsReset_ = false;
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  this.matches.length = 0;
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  this.childPattern_.reset();
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  goog.dom.pattern.AllChildren.prototype.reset.call(this);
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};
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