reduceByDelimitedContent.js

/**
 * Created by elydelacruz on 11/8/16.
 * Simple function to extract delimited content from a string.
 */

'use strict';

/**
 * Returns whether our content has opening and closing delimiters.
 * @param content {String}
 * @param openDelim {String}
 * @param closingDelim {String}
 * @param minDelimitedContentLen {Number} - Default `1`.
 * @returns {boolean}
 */
function hasOpeningAndClosingDelim (content, openDelim, closingDelim, minDelimitedContentLen = 1) {
    return (content.indexOf(openDelim) > -1 ||
        content.indexOf(closingDelim) > (openDelim.length + minDelimitedContentLen));
}

/**
 * Returns normalized aggregator to use for our module.
 * @param aggregator
 * @returns {*}
 */
function normalizeAggregator (aggregator) {
    if (!aggregator.hasOwnProperty('difference')) {
        aggregator.difference = '';
    }
    if (!aggregator.hasOwnProperty('extracted')) {
        aggregator.extracted = [];
    }
    return aggregator;
}

/**
 * Returns reduced content and the results it was reduced by;  E.g.,
 * @todo add extensive example here
 * @note Doesn't take care of nested delimiters.
 * @param content {String} - Required.
 * @param openingDelimiter {String} - Required.
 * @param closingDelimiter {String} - Required.
 * @param aggregatorLike {Object} - Optional.  Default `{}`.
 * @param minDelimitedContentLen {Number} - Optional.  Default `1`.
 * @returns {{difference: String, extracted: Array}}
 */
function reduceByDelimitedContent (content, openingDelimiter, closingDelimiter, aggregatorLike = {}, minDelimitedContentLen = 1) {
    var aggregator = normalizeAggregator(aggregatorLike),
        argsForRemainingCalls;

    // If no opening or closing delimiter return untouched contents
    if (!hasOpeningAndClosingDelim(content, openingDelimiter, closingDelimiter)) {
        aggregator.difference = content;
        return aggregator;
    }

    // Start processing content
    let openingMatch = (new RegExp('(' + openingDelimiter +  ')', 'gim')).exec(content),
        closingMatch = (new RegExp('(' + closingDelimiter + ')', 'gim')).exec(content),
        extractedContent = content.slice(openingMatch.index, closingMatch.index + closingDelimiter.length),
        remainingContent = content.slice(0, openingMatch.index) + 
            content.substring(closingMatch.index + closingDelimiter.length, content.length);

    // Push extracted content
    aggregator.difference = remainingContent;
    aggregator.extracted.push(extractedContent);

    // Prepare for further calls
    argsForRemainingCalls = [remainingContent, openingDelimiter, closingDelimiter, aggregator, minDelimitedContentLen];

    // If content can still be reduced further do so
    if (hasOpeningAndClosingDelim.apply(null, argsForRemainingCalls)) {
        return reduceByDelimitedContent.apply(null, argsForRemainingCalls);
    }

    // Returned reduced and extracted content
    return aggregator;
}

module.exports = reduceByDelimitedContent;