yoastseo-dep/src/languageProcessing/languages/en/helpers/internal/getAdjectiveStem.js

Yoast clientside page analysis

// "use strict";
import { languageProcessing } from "yoastseo-dep";
const { buildFormRule, createRulesFromArrays } = languageProcessing;

/**
 * Constructs a function that checks if the input word can be a specific adjectival form.
 *
 * @param {string}      endsWith            How the form ends.
 * @param {int}         minimumWordLength   How long the word should be to classify for this form.
 * @param {string[]}    exceptions          The list of words with that ending (endsWith) which are not this form.
 *
 * @returns {Function} A function that checks if the input word can be a specific adjectival form.
 */
const constructCanBeFunction = function( endsWith, minimumWordLength, exceptions ) {
	return word => {
		const wordLength = word.length;
		if ( wordLength < minimumWordLength ) {
			return false;
		}

		const doesEndWith = word.substring( wordLength - endsWith.length, wordLength ) === endsWith;
		return doesEndWith && ! exceptions.includes( word );
	};
};

/**
 * Forms the base form from an input word.
 *
 * @param {string}   word                                  The word to build the base form for.
 * @param {Object}   regexAdjective                        The lists of regexes to apply to stem adjectives.
 * @param {Array}    regexAdjective.comparativeToBaseRegex The Array of regex-based rules to bring comparatives to base.
 * @param {Array}    regexAdjective.superlativeToBaseRegex The Array of regex-based rules to bring superlatives to base.
 * @param {Array}    regexAdjective.adverbToBaseRegex      The Array of regex-based rules to bring adverbs to base.
 * @param {Object}   stopAdjectives                        The lists of words that are not adverbs.
 * @param {string[]} stopAdjectives.erExceptions           The list of words that end with -er and are not comparatives.
 * @param {string[]} stopAdjectives.estExceptions          The list of words that end with -est and are not superlatives.
 * @param {string[]} stopAdjectives.lyExceptions           The list of words that end with -ly and are not adverbs.
 *
 * @returns {Object} The base form of the input word.
 */
export default function( word, regexAdjective, stopAdjectives ) {
	/*
	 * Check comparatives: Consider only words of four letters or more (otherwise, words like "per" are being treated
	 * as comparatives).
	 */
	const canBeComparative = constructCanBeFunction( "er", 4, stopAdjectives.erExceptions );
	if ( canBeComparative( word ) ) {
		const comparativeToBaseRegex = createRulesFromArrays( regexAdjective.comparativeToBase );
		return {
			base: buildFormRule( word, comparativeToBaseRegex ) || word,
			guessedForm: "er",
		};
	}

	/*
	 * Check superlatives: Consider only words of five letters or more (otherwise, words like "test" are being treated
	 * as superlatives).
	 */
	const canBeSuperlative = constructCanBeFunction( "est", 5, stopAdjectives.estExceptions );
	if ( canBeSuperlative( word ) ) {
		const superlativeToBaseRegex = createRulesFromArrays( regexAdjective.superlativeToBase );
		return {
			base: buildFormRule( word, superlativeToBaseRegex ) || word,
			guessedForm: "est",
		};
	}

	/*
	 * Check ly-adverbs: Consider only words of five letters or more (otherwise, words like "lily" are being treated
	 * as ly-adverbs).
	 */
	const canBeLyAdverb = constructCanBeFunction( "ly", 5, stopAdjectives.lyExceptions );
	if ( canBeLyAdverb( word ) ) {
		const adverbToBaseRegex = createRulesFromArrays( regexAdjective.adverbToBase );
		return {
			base: buildFormRule( word, adverbToBaseRegex ),
			guessedForm: "ly",
		};
	}

	return {
		base: word,
		guessedForm: "base",
	};
}