linguist-js/dist/analyser/classifiers/byHeuristics.js

Analyse the programming languages used in a folder or from raw content, using the same rules that GitHub Linguist does.

import pcre from '../../program/utils/pcre.js';
import byFilename from './byFilename.js';
import byModeline from './byModeline.js';
import byShebang from './byShebang.js';
function collectPatterns(heuristic, heuristicsData) {
    const patterns = [];
    const add = (value) => {
        if (!value)
            return;
        if (Array.isArray(value)) {
            patterns.push(...value);
        }
        else {
            patterns.push(value);
        }
    };
    add(heuristic.pattern);
    add(heuristicsData.named_patterns?.[heuristic.named_pattern]);
    if (heuristic.and) {
        for (const entry of heuristic.and) {
            add(entry.pattern);
            add(heuristicsData.named_patterns?.[entry.named_pattern]);
        }
    }
    return patterns;
}
export default function byHeuristics(file, candidateLanguages, heuristicsData, langData, opts) {
    // Parse heuristics if applicable
    if (!opts.checkHeuristics || file.content === undefined)
        return [];
    // Skip if file has explicit association
    if (file.attributes?.language)
        return [];
    if (byFilename(file, langData).length)
        return [];
    if (byShebang(file, langData, opts).length)
        return [];
    if (byModeline(file, langData, opts).length)
        return [];
    if (candidateLanguages.length <= 1)
        return [];
    const extension = file.extension ?? '';
    for (const heuristics of heuristicsData.disambiguations ?? []) {
        // Make sure the extension matches the current file
        if (!heuristics.extensions.includes(extension))
            continue;
        // Load heuristic rules
        for (const heuristic of heuristics.rules) {
            // Make sure the language is not an array
            const language = Array.isArray(heuristic.language) ? heuristic.language[0] : heuristic.language;
            const languageGroup = langData[language]?.group;
            const matchesLang = candidateLanguages.includes(language);
            const matchesParent = languageGroup ? candidateLanguages.includes(languageGroup) : false;
            // Make sure the results includes this language
            if (!matchesLang && !matchesParent)
                continue;
            // Normalise heuristic data
            const patterns = collectPatterns(heuristic, heuristicsData);
            // Check file contents and apply heuristic patterns
            if (!patterns.length || patterns.some((pattern) => pcre(pattern).test(file.content))) {
                // Apply heuristics
                return [language];
            }
        }
    }
    return [];
}