diet-yadda/lib/Competition.js

A true BDD framework for JavaScript - slimmed down

/*
 * Copyright 2010 Acuminous Ltd / Energized Work Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* jslint node: true */
"use strict";

var LevenshteinDistanceScore = require('./scores/LevenshteinDistanceScore');
var SameLibraryScore = require('./scores/SameLibraryScore');
var MultiScore = require('./scores/MultiScore');
var $ = require('./Array');

// Understands appropriateness of macros in relation to a specific step
var Competition = function(step, macros, last_macro) {

    var results = [];

    this.validate = function() {
        if (is_undefined()) return { step: step, valid: false, reason: 'Undefined Step' };
        if (is_ambiguous()) return { step: step, valid: false, reason: 'Ambiguous Step (Patterns [' + winning_patterns() + '] are all equally good candidates)' };
        return { step: step, valid: true, winner: this.winner() };
    };

    this.clear_winner = function() {
        if (is_undefined()) throw new Error('Undefined Step: [' + step + ']');
        if (is_ambiguous()) throw new Error('Ambiguous Step: [' + step + ']. Patterns [' + winning_patterns() + '] match equally well.');
        return this.winner();
    };

    function is_undefined() {
        return results.length === 0;
    }

    function is_ambiguous() {
        return (results.length > 1) && results[0].score.equals(results[1].score);
    }

    this.winner = function() {
        return results[0].macro;
    };

    function winning_patterns() {
        return results.find_all(by_winning_score).collect(macro_signatures).join(', ');
    }

    function rank(step, macros) {
        results = macros.collect(function(macro) {
            return {
                macro: macro,
                score: new MultiScore([
                    new LevenshteinDistanceScore(step, macro.levenshtein_signature()),
                    new SameLibraryScore(macro, last_macro)
                ])
            };
        }).sort(by_ascending_score);
    }

    function by_ascending_score(a, b) {
        return b.score.compare(a.score)
    }

    function by_winning_score(result) {
        return result.score.equals(results[0].score);
    }

    function macro_signatures(result) {
        return result.macro.toString();
    }

    rank(step, $(macros));
};

module.exports = Competition;