* @param {[FileMetadata]} fileMetadatas - gitStream's list of metadata about file changes in the PR including path
 * @returns {[Object]} Returns a list of objects for each platform containing info about the changes to files in that platform
 * @example {{ owners | categorize(branch.diff.files_metadata) }}
 */

function categorize(fileOwners, fileMetadatas) {

/**
 * @module nullToEmpty
 * @description Returns the specified value if non-null, otherwise an empty array.
 * @param {Object} input - The object to investigate
 * @returns Object - The specified value if non-null, otherwise an empty array
 * @example {{ readField('jvm', 'files') | nullToEmpty }}
 */
function nullToEmpty(input) {
    let output;
    if (input) {
        output = input;
    } else {
        output = [];
    }

    let preppedStatistics = statistics.filter(s => s.files.length > 0)
        .sort(s => -(s.additions + s.deletions));

    let totalAdditions = Object.values(preppedStatistics).reduce((acc, summary) => acc + summary.additions, 0);
    let totalDeletions = Object.values(preppedStatistics).reduce((acc, summary) => acc + summary.deletions, 0);
    let newRatio = totalAdditions / (totalAdditions + totalDeletions) * 100;

 * @param {[FileMetadata]} fileMetadatas - gitStream's list of metadata about file changes in the PR including path
 * @returns {[Object]} Returns list of computed summary statistic objects for each platform in the input groupedFiles
 * @example {{ fileOwners | categorize(branch.diff.files_metadata) | changeStatistics(branch.diff.files_metadata) }}
 */

    // Check if always enabled, or enabled by comment
    if (automationActivations.includes('always')) {
        result = true;
    } else {
        result = Object.values(pr.comments).some(comment => {
            const checks = extractCheckNames(comment.content);
            if (checks.includes(automationName)) {
                return true;
            }
        });
    }

// A simple implementation of make-array
function makeArray (subject) {
    return Array.isArray(subject)
        ? subject
        : [subject]
}

const EMPTY = ''
const SPACE = ' '
const ESCAPE = '\\'
const REGEX_TEST_BLANK_LINE = /^\s+$/
const REGEX_INVALID_TRAILING_BACKSLASH = /(?:[^\\]|^)\\$/
const REGEX_REPLACE_LEADING_EXCAPED_EXCLAMATION = /^\\!/
const REGEX_REPLACE_LEADING_EXCAPED_HASH = /^\\#/
const REGEX_SPLITALL_CRLF = /\r?\n/g

/**
 * @module readField
 * @description Returns one field for a particular named object in a list of objects.
 * @param {[Object]} objects - The objects to search
 * @param {String} objectName - The name of the particular object to find
 * @param {String} fieldName - The name of the field for the group to return
 * @returns String - The specified value
 * @example {{ files | byPlatform | categorize(branch.diff.files_metadata) | readField('jvm', 'name') }}
 */

/**
 * @module byCodeowner
 * @description Groups the PR's files' by owner based on the CODEOWNERs file.
 * @param {string[]} files - the gitStream's files context variable
 * @param {Object} pr - the gitStream's pr context variable
 * @param {string} token - access token with repo:read scope, used to read the CODEOWNERS file
 * @param {string} pathToCodeOwners - path from repo root to CODEOWNERS file
 * @returns {Map} - Map from owner name to list of files they own