matchme

Simple Object Query Language

matchme

This is an experimental library that will allow object matching based on a simple query language plus chainable function interface.

  • The equality operator == is now a case-senstive match
  • A loose equality operator ~= can be used for case insensitive matches.
  • Regex operators are now implemented using =? for a match and !? for not.

Matching is done at an object level against object properties, e.g.

var matchme = require('matchme');
var test = { name: 'Ted', age: 40 };
 
console.log(matchme(test, 'name == Ted'));
// --> true 
 
console.log(matchme(test, 'name == ted'));
// --> false 
 
console.log(matchme(test, 'name ~= ted'));
// --> true 
 
console.log(matchme(test, 'age > 25'));
// --> true 
 
console.log(matchme(test, 'name ~= ted && age > 45'));
// --> false 
 

In addition matchme can be used in conjunction the filter function (both the native JS implemenation or underscores):

var matchme = require('matchme');
var people = [
  { name: 'Ted', age: 40 },
  { name: 'Bill', age: 42 }
];
 
console.log(people.filter(matchme.filter('age > 40')));
// --> [ { name: 'Bill', age: 42 }] 

An example using the pull-stream module is shown below. This example reads data from a data file downloaded from geonames and loaded in through the geonames module which provides a pull-stream source.

var geonames = require('geonames');
var pull = require('pull-stream');
var matchme = require('matchme');
 
console.log('Places with a population > 500,000 (limited to first 10):');
 
pull(
  geonames.read(__dirname + '/data/AU.txt'),
  pull.filter(matchme.filter('featureClass == P && population > 500000')),
  pull.take(10),
  pull.drain(function(place) {
    console.log(place.name);
  })
);
 

Additionally, here is another example that uses a matchme regex to identify places that are named as Islands but are classified as something else:

var geonames = require('geonames');
var pull = require('pull-stream');
var matchme = require('matchme');
 
pull(
  geonames.read(__dirname + '/data/AU.txt'),
  pull.filter(matchme.filter('name =~ /Island$/ && featureCode != ISL')),
  pull.drain(function(place) {
    console.log(place.name + ' might seem like an island but is in fact a ' + place.featureCode);
  })
);
 

In general, the use of eval is considered evil. I have avoided using it for many, many years. That said matchme makes use of eval to simplifying the parsing required to properly deal with complex expressions (BOMDAS, etc).

Check whether the specified property of the target object is greater than the specified value. If the optional result argument is passed to the function then the result is passed back in that object. If not the result is stored in the local ok property of the matcher instance. Other comparison methods use the same principle as this function.

Greater than or equal to check.

Less than property value check

Less than or equal to check

Equality check

Equality check (case insensitive)

Copyright (c) 2014 Damon Oehlman damon.oehlman@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

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