htmldiff

htmldiff.js

(function() {
  var Match, calculate_operations, consecutive_where, create_index, diff, find_match, find_matching_blocks, html_to_tokens, is_end_of_tag, is_start_of_tag, is_tag, is_whitespace, isnt_tag, op_map, recursively_find_matching_blocks, render_operations, wrap;

  is_end_of_tag = function(char) {
    return char === '>';
  };

  is_start_of_tag = function(char) {
    return char === '<';
  };

  is_whitespace = function(char) {
    return /^\s+$/.test(char);
  };

  is_tag = function(token) {
    return /^\s*<[^>]+>\s*$/.test(token);
  };

  isnt_tag = function(token) {
    return !is_tag(token);
  };

  Match = (function() {
    function Match(start_in_before, start_in_after, length) {
      this.start_in_before = start_in_before;
      this.start_in_after = start_in_after;
      this.length = length;
      this.end_in_before = (this.start_in_before + this.length) - 1;
      this.end_in_after = (this.start_in_after + this.length) - 1;
    }

    return Match;

  })();

  html_to_tokens = function(html) {
    var char, current_word, mode, words, _i, _len;
    mode = 'char';
    current_word = '';
    words = [];
    for (_i = 0, _len = html.length; _i < _len; _i++) {
      char = html[_i];
      switch (mode) {
        case 'tag':
          if (is_end_of_tag(char)) {
            current_word += '>';
            words.push(current_word);
            current_word = '';
            if (is_whitespace(char)) {
              mode = 'whitespace';
            } else {
              mode = 'char';
            }
          } else {
            current_word += char;
          }
          break;
        case 'char':
          if (is_start_of_tag(char)) {
            if (current_word) {
              words.push(current_word);
            }
            current_word = '<';
            mode = 'tag';
          } else if (/\s/.test(char)) {
            if (current_word) {
              words.push(current_word);
            }
            current_word = char;
            mode = 'whitespace';
          } else if (/[\w\#@]+/i.test(char)) {
            current_word += char;
          } else {
            if (current_word) {
              words.push(current_word);
            }
            current_word = char;
          }
          break;
        case 'whitespace':
          if (is_start_of_tag(char)) {
            if (current_word) {
              words.push(current_word);
            }
            current_word = '<';
            mode = 'tag';
          } else if (is_whitespace(char)) {
            current_word += char;
          } else {
            if (current_word) {
              words.push(current_word);
            }
            current_word = char;
            mode = 'char';
          }
          break;
        default:
          throw new Error("Unknown mode " + mode);
      }
    }
    if (current_word) {
      words.push(current_word);
    }
    return words;
  };

  find_match = function(before_tokens, after_tokens, index_of_before_locations_in_after_tokens, start_in_before, end_in_before, start_in_after, end_in_after) {
    var best_match_in_after, best_match_in_before, best_match_length, index_in_after, index_in_before, locations_in_after, looking_for, match, match_length_at, new_match_length, new_match_length_at, _i, _j, _len;
    best_match_in_before = start_in_before;
    best_match_in_after = start_in_after;
    best_match_length = 0;
    match_length_at = {};
    for (index_in_before = _i = start_in_before; start_in_before <= end_in_before ? _i < end_in_before : _i > end_in_before; index_in_before = start_in_before <= end_in_before ? ++_i : --_i) {
      new_match_length_at = {};
      looking_for = before_tokens[index_in_before];
      locations_in_after = index_of_before_locations_in_after_tokens[looking_for];
      for (_j = 0, _len = locations_in_after.length; _j < _len; _j++) {
        index_in_after = locations_in_after[_j];
        if (index_in_after < start_in_after) {
          continue;
        }
        if (index_in_after >= end_in_after) {
          break;
        }
        if (match_length_at[index_in_after - 1] == null) {
          match_length_at[index_in_after - 1] = 0;
        }
        new_match_length = match_length_at[index_in_after - 1] + 1;
        new_match_length_at[index_in_after] = new_match_length;
        if (new_match_length > best_match_length) {
          best_match_in_before = index_in_before - new_match_length + 1;
          best_match_in_after = index_in_after - new_match_length + 1;
          best_match_length = new_match_length;
        }
      }
      match_length_at = new_match_length_at;
    }
    if (best_match_length !== 0) {
      match = new Match(best_match_in_before, best_match_in_after, best_match_length);
    }
    return match;
  };

  recursively_find_matching_blocks = function(before_tokens, after_tokens, index_of_before_locations_in_after_tokens, start_in_before, end_in_before, start_in_after, end_in_after, matching_blocks) {
    var match;
    match = find_match(before_tokens, after_tokens, index_of_before_locations_in_after_tokens, start_in_before, end_in_before, start_in_after, end_in_after);
    if (match != null) {
      if (start_in_before < match.start_in_before && start_in_after < match.start_in_after) {
        recursively_find_matching_blocks(before_tokens, after_tokens, index_of_before_locations_in_after_tokens, start_in_before, match.start_in_before, start_in_after, match.start_in_after, matching_blocks);
      }
      matching_blocks.push(match);
      if (match.end_in_before <= end_in_before && match.end_in_after <= end_in_after) {
        recursively_find_matching_blocks(before_tokens, after_tokens, index_of_before_locations_in_after_tokens, match.end_in_before + 1, end_in_before, match.end_in_after + 1, end_in_after, matching_blocks);
      }
    }
    return matching_blocks;
  };

  create_index = function(p) {
    var idx, index, token, _i, _len, _ref;
    if (p.find_these == null) {
      throw new Error('params must have find_these key');
    }
    if (p.in_these == null) {
      throw new Error('params must have in_these key');
    }
    index = {};
    _ref = p.find_these;
    for (_i = 0, _len = _ref.length; _i < _len; _i++) {
      token = _ref[_i];
      index[token] = [];
      idx = p.in_these.indexOf(token);
      while (idx !== -1) {
        index[token].push(idx);
        idx = p.in_these.indexOf(token, idx + 1);
      }
    }
    return index;
  };

  find_matching_blocks = function(before_tokens, after_tokens) {
    var index_of_before_locations_in_after_tokens, matching_blocks;
    matching_blocks = [];
    index_of_before_locations_in_after_tokens = create_index({
      find_these: before_tokens,
      in_these: after_tokens
    });
    return recursively_find_matching_blocks(before_tokens, after_tokens, index_of_before_locations_in_after_tokens, 0, before_tokens.length, 0, after_tokens.length, matching_blocks);
  };

  calculate_operations = function(before_tokens, after_tokens) {
    var action_map, action_up_to_match_positions, index, is_single_whitespace, last_op, match, match_starts_at_current_position_in_after, match_starts_at_current_position_in_before, matches, op, operations, position_in_after, position_in_before, post_processed, _i, _j, _len, _len1;
    if (before_tokens == null) {
      throw new Error('before_tokens?');
    }
    if (after_tokens == null) {
      throw new Error('after_tokens?');
    }
    position_in_before = position_in_after = 0;
    operations = [];
    action_map = {
      'false,false': 'replace',
      'true,false': 'insert',
      'false,true': 'delete',
      'true,true': 'none'
    };
    matches = find_matching_blocks(before_tokens, after_tokens);
    matches.push(new Match(before_tokens.length, after_tokens.length, 0));
    for (index = _i = 0, _len = matches.length; _i < _len; index = ++_i) {
      match = matches[index];
      match_starts_at_current_position_in_before = position_in_before === match.start_in_before;
      match_starts_at_current_position_in_after = position_in_after === match.start_in_after;
      action_up_to_match_positions = action_map[[match_starts_at_current_position_in_before, match_starts_at_current_position_in_after].toString()];
      if (action_up_to_match_positions !== 'none') {
        operations.push({
          action: action_up_to_match_positions,
          start_in_before: position_in_before,
          end_in_before: (action_up_to_match_positions !== 'insert' ? match.start_in_before - 1 : void 0),
          start_in_after: position_in_after,
          end_in_after: (action_up_to_match_positions !== 'delete' ? match.start_in_after - 1 : void 0)
        });
      }
      if (match.length !== 0) {
        operations.push({
          action: 'equal',
          start_in_before: match.start_in_before,
          end_in_before: match.end_in_before,
          start_in_after: match.start_in_after,
          end_in_after: match.end_in_after
        });
      }
      position_in_before = match.end_in_before + 1;
      position_in_after = match.end_in_after + 1;
    }
    post_processed = [];
    last_op = {
      action: 'none'
    };
    is_single_whitespace = function(op) {
      if (op.action !== 'equal') {
        return false;
      }
      if (op.end_in_before - op.start_in_before !== 0) {
        return false;
      }
      return /^\s$/.test(before_tokens.slice(op.start_in_before, +op.end_in_before + 1 || 9e9));
    };
    for (_j = 0, _len1 = operations.length; _j < _len1; _j++) {
      op = operations[_j];
      if (((is_single_whitespace(op)) && last_op.action === 'replace') || (op.action === 'replace' && last_op.action === 'replace')) {
        last_op.end_in_before = op.end_in_before;
        last_op.end_in_after = op.end_in_after;
      } else {
        post_processed.push(op);
        last_op = op;
      }
    }
    return post_processed;
  };

  consecutive_where = function(start, content, predicate) {
    var answer, index, last_matching_index, token, _i, _len;
    content = content.slice(start, +content.length + 1 || 9e9);
    last_matching_index = void 0;
    for (index = _i = 0, _len = content.length; _i < _len; index = ++_i) {
      token = content[index];
      answer = predicate(token);
      if (answer === true) {
        last_matching_index = index;
      }
      if (answer === false) {
        break;
      }
    }
    if (last_matching_index != null) {
      return content.slice(0, +last_matching_index + 1 || 9e9);
    }
    return [];
  };

  wrap = function(tag, content) {
    var length, non_tags, position, rendering, tags;
    rendering = '';
    position = 0;
    length = content.length;
    while (true) {
      if (position >= length) {
        break;
      }
      non_tags = consecutive_where(position, content, isnt_tag);
      position += non_tags.length;
      if (non_tags.length !== 0) {
        rendering += "<" + tag + ">" + (non_tags.join('')) + "</" + tag + ">";
      }
      if (position >= length) {
        break;
      }
      tags = consecutive_where(position, content, is_tag);
      position += tags.length;
      rendering += tags.join('');
    }
    return rendering;
  };

  op_map = {
    equal: function(op, before_tokens, after_tokens) {
      return before_tokens.slice(op.start_in_before, +op.end_in_before + 1 || 9e9).join('');
    },
    insert: function(op, before_tokens, after_tokens) {
      var val;
      val = after_tokens.slice(op.start_in_after, +op.end_in_after + 1 || 9e9);
      return wrap('ins', val);
    },
    "delete": function(op, before_tokens, after_tokens) {
      var val;
      val = before_tokens.slice(op.start_in_before, +op.end_in_before + 1 || 9e9);
      return wrap('del', val);
    }
  };

  op_map.replace = function(op, before_tokens, after_tokens) {
    return (op_map["delete"](op, before_tokens, after_tokens)) + (op_map.insert(op, before_tokens, after_tokens));
  };

  render_operations = function(before_tokens, after_tokens, operations) {
    var op, rendering, _i, _len;
    rendering = '';
    for (_i = 0, _len = operations.length; _i < _len; _i++) {
      op = operations[_i];
      rendering += op_map[op.action](op, before_tokens, after_tokens);
    }
    return rendering;
  };

  diff = function(before, after, callback) {
    var ops;
    if (before === after) {
      return 0;
    }
    before = html_to_tokens(before);
    after = html_to_tokens(after);
    ops = calculate_operations(before, after);
    callback( render_operations(before, after, ops) );
  };

  diff.html_to_tokens = html_to_tokens;

  diff.find_matching_blocks = find_matching_blocks;

  find_matching_blocks.find_match = find_match;

  find_matching_blocks.create_index = create_index;

  diff.calculate_operations = calculate_operations;

  diff.render_operations = render_operations;

  if (typeof define === 'function') {
    define([], function() {
      return diff;
    });
  } else if (typeof module !== "undefined" && module !== null) {
    module.exports = diff;
  } else {
    this.htmldiff = diff;
  }

}).call(this);