regexplus/index.js

RegExp Plus

var RE_PLUS = /\((\?<=|\?<!|\?<\w+>|.)/g;
var RE_NAMED = /\(\?<(\w+)>/g; // 命名分组。
var RE_REV_PRE = /\(\?<=/g; // 反向预搜索。
var RE_REV_PRE_NOT = /\(\?<!/g; // 反向预搜索不匹配。

function RegExplus(source, flags) {
  if (!flags) {
    flags = '';
  }
  this.source = source;
  this._plus = [null];
  this._reverse_pre_search = [];
  this._reverse_pre_search_not_match = [];
  var _source = source.replace(RE_PLUS, function($0, flag, subreg) {
    if (flag === '?:') { // unmatched group.
      return $0;
    } else if (flag === '?=') { // 正向预搜索。
      return $0;
    } else if (flag === '?=') { // 正向预搜索不匹配。
      return $0;
    } else if (flag === '?<=') { // 反向预搜索。
      this._plus.push({
        type: 'reverse-match',
        regexp: new RegExp(subreg, flags),
      });
    } else if (flag === '?<!') { // 反向预搜索不匹配。
      this._plus.push({
        type: 'reverse-mismatch',
        regexp: new RegExp(subreg, flags),
      });
    } else if (flag.startsWith('?<') && flag.endsWith('>')) {  // 命名分组。
      this._plus.push({
        type: 'named-group',
        name: flag.substring(2, flag.length - 1),
      });
    } else {// 普通分组。
      this._plus.push({
        type: 'group',
      });
      return $0;
    }
    return '(';
  }.bind(this));
  this._regexp = new RegExp(_source, flags);
  this.lastIndex = 0;
  this.global = flags.indexOf('g') >= 0;
  this.multiline = flags.indexOf('m') >= 0;
  this.ignoreCase = flags.indexOf('i') >= 0;
}

RegExplus.prototype = {
  exec: function(string) {
    var matched = this._regexp.exec(string);
    if (!matched) {
      return null;
    }
    // named group.
    for (var i=1, l=matched.length; i<l; i++) {
      switch(this._plus[i].type){
      case 'group':
        break;
      case 'named-group':
        matched[ this._plus[i].name ] = matched[i];
        break;
      case 'reverse-match':
        if (this._plus[i].regexp.test(matched[i])) {
          matched.splice(i, 1);
        } else {
          return null;
        }
        break;
      case 'reverse-mismatch':
        if (!this._plus[i].regexp.test(matched[i])) {
          matched.splice(i, 1);
        } else {
          return null;
        }
        break;
      default:
      // TODO: 反向预搜索
        throw new Error("Unknow type.");
      }
    }
    return matched;
  },
  test: function(string) {
    return this.exec(string) !== null;
  },
  valueOf: function() {
    return this._regexp;
  },
  toString: function() {
    return '/' + this.source + '/' +
            (this.ignoreCase ? 'i' : '') +
            (this.multiline ? 'm' : '') +
            (this.global ? 'g' : '');
  },
};


module.exports = RegExplus;