A parser for parsing a string into parameters object.

Parameters parser will sequentially use provided rules to match a input string, trying to extract parameters from it. If a rule fails to parse the input, parser will try next one, till all the rules are tried. The parser will return the result as soon as a succeeded parse occurs.

Once require the module, you could use it as a constructor. Pass your rules array into it, it will return a parser based on the rules.

var ParamsParser = require('paramsParser');
var rules = [rule1, rule2, rule3];
var parser = new ParamsParser(rules);
var params = parser.parse(inputString);

The parser will apply the rules one by one to the input string, till he make a success. If all the rules return non-true values, a NO_MATCH_RULE error will be thrown.

In paramsParse, you can use regular expression or a function to express your parsing rules.

If rule.reg is given, paramsParser will match the input string with it, and pass the result into getter. If the result returned from getter is true, we'll regard it as a succeeded match.

var rule = {

  // a regex object or a string, will use it with .match
  reg: /https*:\/\/([^\/]+)(.*)/, 

  // a getter function
  getter: function (result) {

    return {
      url: result[0],
      host: result[1],
      path: result[2]
    };

  } // a function

}

try {

  var parser = new ParamsParser([rule]);
  var params = parser.parse('http://www.fizz.com/buzz.html');
  console.log(params.url); // http://www.fizz.com/buzz.html
  console.log(params.host); // www.fizz.com
  console.log(params.path); // /buzz.html

} catch (err) {

  console.log(err); // PARAMS_PARSER * err -> NO_MATCH_RULE * input -> xxxx

}

If rule.reg is not provided, paramsParser will pass the input string into the getter function, and regards a non-false return as a succeeded parse result.

var rule = {

  getter: function (inStr) {

    var url = require('url');
    var result = url.parse(inStr, true);
    
    return {
      url: result.href,
      path: result.path + '&numberOfTheBeast=666',
      fizz: 'buzz'
    };

  }

};
var parser = new ParamsParser([rule]);

try {

  var params = parser.parse('http://www.booo.com/search.html');
  console.log(params.url); // http://www.booo.com/search.html
  console.log(params.path); // search.html
  console.log(params.fizz); // buzz

} catch (err) {

  console.log(err);

}