SOURCE CODE: Uize.Loc.Plurals.RuleParser (view docs)

/*______________
|       ______  |   U I Z E    J A V A S C R I P T    F R A M E W O R K
|     /      /  |   ---------------------------------------------------
|    /    O /   |    MODULE : Uize.Loc.Plurals.RuleParser Package
|   /    / /    |
|  /    / /  /| |    ONLINE : http://www.uize.com
| /____/ /__/_| | COPYRIGHT : (c)2014-2016 UIZE
|          /___ |   LICENSE : Available under MIT License or GNU General Public License
|_______________|             http://www.uize.com/license.html
*/

/* Module Meta Data
  type: Package
  importance: 1
  codeCompleteness: 5
  docCompleteness: 5
*/

/*?
  Introduction
    The =Uize.Loc.Plurals.RuleParser= module provides methods for parsing [[http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html][CLDR plural rules]] defined using the [[http://unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules][CLDR plural rule syntax]].

    *DEVELOPERS:* `Chris van Rensburg`
*/

Uize.module ({
  name:'Uize.Loc.Plurals.RuleParser',
  required:[
    'Uize.Str.Split',
    'Uize.Str.Trim',
    'Uize.Util.RegExpComposition'
  ],
  builder:function () {
    'use strict';

    var
      /*** Variables for Scruncher Optimization ***/
        _split = Uize.Str.Split.split,

      /*** references to static methods used internally ***/
        _ruleToJs,
        _rulesToJs,

      /*** General Variables ***/
        _ruleRegExpComposition = Uize.Util.RegExpComposition ({
          digit:/\d/,
          value:/{digit}+/,
          decimalValue:/{value}(\.{value})?/,
          range:/{value}\.\.{value}/,
          sampleRange:/{decimalValue}(~{decimalValue})?/,
          samples:/{sampleRange}(\s*,\s*{sampleRange})*(\s*,\s*(…|\.\.\.))?/,
          integerOrDecimalSamples:/@(integer|decimal)\s+{samples}/g
        }),
        _samplesRegExp = _ruleRegExpComposition.get ('integerOrDecimalSamples'),
        _orRegExp = /\s+or\s+/,
        _andRegExp = /\s+and\s+/,
        _relationPartsRegExp = /^\s*(.+?)\s*(!?=)\s*(.+?)\s*$/,
        _rangeDetectorRegExp = /\.\.|,/
    ;

    return Uize.package ({
      ruleToJs:_ruleToJs = function (_pluralRuleStr) {
        return Uize.Str.Trim.trim (
          Uize.map (
            _split (_pluralRuleStr.replace (_samplesRegExp,''),_orRegExp), // remove samples, split or conditions
            function (_andCondition) {
              return Uize.map (
                _split (_andCondition,_andRegExp),
                function (_relation) {
                  var
                    _relationParts = _relation.match (_relationPartsRegExp),
                    _operandA = _relationParts [1],
                    _operator = _relationParts [2],
                    _operandB = _relationParts [3]
                  ;
                  if (_operator == '=')
                    _operator = '=='
                  ;
                  return (
                    _rangeDetectorRegExp.test (_operandB)
                      ?
                        (_operator == '!=' ? '!' : '') +
                        'within (' +
                          _operandA + ',' +
                          '[' +
                            _operandB.replace (
                              /(\d+)\.\.(\d+)/g,
                              function (_match,_rangeLimitA,_rangeLimitB) {
                                return '[' + _rangeLimitA + ',' + _rangeLimitB + ']';
                              }
                            ) +
                          ']' +
                        ')'
                      : _operandA + ' ' + _operator + ' ' + _operandB
                  );
                }
              ).join (' && ');
            }
          ).join (' || ')
        );
        /*?
          Static Methods
            Uize.Loc.Plurals.RuleParser.ruleToJs
              Returns a string, representing the CLDR plural rule in the form of a JavaScript expression.

              SYNTAX
              .......................................................................
              jsExpressionSTR = Uize.Loc.Plurals.RuleParser.ruleToJs (pluralRuleSTR);
              .......................................................................
        */
      },

      rulesToJs:_rulesToJs = function (_pluralRulesMap) {
        delete (_pluralRulesMap = Uize.copy (_pluralRulesMap)).other;
        var
          _pluralRuleNo = -1,
          _pluralRuleNames = Uize.keys (_pluralRulesMap)
        ;
        function _getPluralRuleCondition () {
          var _pluralRuleName = _pluralRuleNames [++_pluralRuleNo];
          return (
            _pluralRuleName
              ? (
                _ruleToJs (_pluralRulesMap [_pluralRuleName]) +
                ' ? \'' + _pluralRuleName + '\'' +
                ' : ' + _getPluralRuleCondition ()
              )
              : '\'other\''
          );
        }
        return _getPluralRuleCondition ();
      },

      rulesToJsFunctionStr:function (_pluralRulesMap) {
        return (
          'function (n,i,f,t,v,w,within) {\n' +
            '\treturn ' + _rulesToJs (_pluralRulesMap) + ';\n' +
          '}\n'
        );
      },

      rulesToJsFunction:function (_pluralRulesMap) {
        return Function (
          'n', 'i', 'f', 't', 'v', 'w', 'within',
          'return ' + _rulesToJs (_pluralRulesMap) + ';'
        );
      }
    });
  }
});