feather-route-matcher/feather-route-matcher.js

featherweight url to handler matching

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  typeof define === 'function' && define.amd ? define(factory) :
  (global = global || self, global.createMatcher = factory());
}(this, (function () { 'use strict';

  // regexes borrowed from backbone
  var optionalParam = /\((.*?)\)/g;
  var namedParam = /(\(\?)?:\w+/g;
  // eslint-disable-next-line no-useless-escape
  var escapeRegExp = /[\-{}\[\]+?.,\\\^$|#\s]/g;
  var splatParam = /\*/g;

  // Parses a URL pattern such as `/users/:id`
  // and builds and returns a regex that can be used to
  // match said pattern. Credit for these
  // regexes belongs to Jeremy Ashkenas and the
  // other maintainers of Backbone.js
  //
  // It has been modified for extraction of
  // named parameters from the URL
  var parsePattern = function (pattern) {
    var names = [];
    pattern = pattern
      .replace(escapeRegExp, '\\$&')
      .replace(optionalParam, '(?:$1)?')
      .replace(namedParam, function (match, optional) {
        names.push(match.slice(1));
        return optional ? match : '([^/?]+)'
      })
      .replace(splatParam, function () {
        names.push('path');
        return '([^?]*?)'
      });

    return {
      regExp: new RegExp('^' + pattern + '(?:\\?([\\s\\S]*))?$'),
      namedParams: names
    }
  };

  function index (routes) {
    var keys = Object.keys(routes);
    var routeCache = {};

    // loop through each route we're
    // and build the shell of our
    // route cache.
    for (var item in routes) {
      routeCache[item] = {
        value: routes[item]
      };
    }

    // main result is a function that can be called
    // with the url
    return function (url) {
      var params;
      var route;

      // start looking for matches
      var matchFound = keys.some(function (key) {
        var parsed;

        // fetch the route pattern from the cache
        // there will always be one
        route = routeCache[key];

        // if the route doesn't already have
        // a regex we never generated one
        // so we do that here lazily.
        // Parse the pattern to generate the
        // regex once, and store the result
        // for next time.
        if (!route.regExp) {
          parsed = parsePattern(key);
          route.regExp = parsed.regExp;
          route.namedParams = parsed.namedParams;
          route.pattern = key;
        }

        // run our cached regex
        var result = route.regExp.exec(url);

        // if null there was no match
        // returning falsy here continues
        // the `Array.prototype.some` loop
        if (!result) {
          return
        }

        // remove other cruft from result
        result = result.slice(1, -1);

        // reduce our match to an object of named parameters
        // we've extracted from the url
        params = result.reduce(function (obj, val, index) {
          if (val) {
            obj[route.namedParams[index]] = val;
          }
          return obj
        }, {});

        // stops the loop
        return true
      });

      // no routes matched
      if (!matchFound) {
        return null
      }

      return {
        value: route.value,
        params: params,
        url: url,
        pattern: route.pattern
      }
    }
  }

  return index;

})));
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