retext-overuse/index.js

Check words for overuse with Retext

/**
 * @author Duncan Beaton
 * @copyright 2016 Duncan Beaton
 * @license MIT
 * @module retext:overuse
 * @fileoverview Word overuse with Retext.
 */

'use strict';

/*
 * Dependencies.
 */

var keys = require('object-keys');
var difference = require('array-differ');
var search = require('nlcst-search');
var nlcstToString = require('nlcst-to-string');
var quotation = require('quotation');
var stopwords = require('stopwords').english;
var thesaurus = require('thesaurus/lib/th_en_US_new');

/*
 * Methods.
 */

/**
 * Get any duplicated Words in `node`.
 *
 * @param {Node} node - Parent to search in.
 * @param {Array.<string>} phrases - Phrases to search for.
 * @return {Object}
 */
function getDuplicates(node, phrases) {
    var duplicates = {};
    search(node, phrases, function (match, position, parent, phrase) {
        duplicates[phrase] = duplicates[phrase] ? duplicates[phrase] + 1 : 1
    });
    return duplicates;
}

/**
 * Get duplicates that are used too frequently.
 *
 * @param {Object} duplicates - Phrases to search for.
 * @param {number} limit - Number of times phrase must have been used.
 * @return {Array.<string>}
 */
function getOveruse(duplicates, limit) {
    var duplicate;
    for (duplicate in duplicates) {
        if (duplicates[duplicate] < limit) {
            delete duplicates[duplicate]
        }
    }
    return keys(duplicates);
}

/**
 * Attach.
 *
 * @param {Retext} retext - Instance.
 * @param {Object?} [options] - Configuration.
 * @param {Object.<Object>?} [options.list] - Phrases with suggestions
 * @param {Object.<Array>?} [options.ignore] - Phrases in the list
 * to ignore.
 * @param {Object.<number>?} [options.limit] - Number of times phrase
 * must have been used.
 * @return {Function} - `transformer`.
 */
function attacher(retext, options) {
    var settings = options || {};
    var ignore = settings.ignore || stopwords;
    var patterns = settings.list || thesaurus;
    var limit = settings.limit || 3;
    var list = keys(patterns);
    var phrases = difference(list, ignore);

    /**
     * Search `tree` for overuse.
     *
     * @param {Node} tree - NLCST node.
     * @param {VFile} file - Virtual file.
     */
    function transformer(tree, file) {
        var duplicates = getDuplicates(tree, phrases)
        var overuse = getOveruse(duplicates, limit)

        search(tree, overuse, function (match, position, parent, phrase) {
            var suggestions = patterns[phrase];
            var value = quotation(nlcstToString(match), '“', '”');

            var reason = 'Replace ' + value + ' with ' +
                quotation(suggestions, '“', '”').join(', ');

            var message = file.warn(reason, {
                'start': match[0].position.start,
                'end': match[match.length - 1].position.end
            });

            message.ruleId = phrase;
            message.source = 'retext-overuse';
            message.actual = value.slice(1, -1);
            message.expected = suggestions;
        });
    }
    return transformer;
}

/*
 * Expose.
 */

module.exports = attacher;