maplibre-gl/src/util/script_detection.test.ts

BSD licensed community fork of mapbox-gl, a WebGL interactive maps library

import {describe, test, expect} from 'vitest';
import {charIsWhitespace, charAllowsLetterSpacing, charInComplexShapingScript, charInRTLScript} from './script_detection.ts';

describe('charIsWhitespace', () => {
    test('detects whitespace', () => {
        expect(charIsWhitespace(' '.codePointAt(0))).toBe(true);
        expect(charIsWhitespace('\t'.codePointAt(0))).toBe(true);
        expect(charIsWhitespace('\v'.codePointAt(0))).toBe(true);
        expect(charIsWhitespace('\f'.codePointAt(0))).toBe(true);
        expect(charIsWhitespace('\r'.codePointAt(0))).toBe(true);
        expect(charIsWhitespace('\n'.codePointAt(0))).toBe(true);
    });
});

describe('charAllowsLetterSpacing', () => {
    test('allows letter spacing of Latin text', () => {
        expect(charAllowsLetterSpacing('A'.codePointAt(0))).toBe(true);
    });

    test('disallows letter spacing of Arabic text', () => {
        // Arabic
        expect(charAllowsLetterSpacing('۳'.codePointAt(0))).toBe(false);
        // Arabic Supplement
        expect(charAllowsLetterSpacing('ݣ'.codePointAt(0))).toBe(false);
        // Arabic Extended-A
        expect(charAllowsLetterSpacing('ࢳ'.codePointAt(0))).toBe(false);
        // Arabic Extended-B
        expect(charAllowsLetterSpacing('࢐'.codePointAt(0))).toBe(false);
        // Arabic Presentation Forms-A
        expect(charAllowsLetterSpacing('ﰤ'.codePointAt(0))).toBe(false);
        // Arabic Presentation Forms-B
        expect(charAllowsLetterSpacing('ﺽ'.codePointAt(0))).toBe(false);
    });

    test('disallows letter spacing of cursive scripts written outside the basic plane', () => {
        // Duployan
        expect(charAllowsLetterSpacing(0x1bc00)).toBe(false);
        // Old Uyghur
        expect(charAllowsLetterSpacing(0x10f70)).toBe(false);
    });

    test('disallows letter spacing of every script whose letters join, not only Arabic', () => {
        // Mongolian
        expect(charAllowsLetterSpacing(0x1820)).toBe(false);
        // Syriac
        expect(charAllowsLetterSpacing(0x0710)).toBe(false);
        // Adlam
        expect(charAllowsLetterSpacing(0x1e900)).toBe(false);
        // N'Ko
        expect(charAllowsLetterSpacing(0x07ca)).toBe(false);
        // Mandaic
        expect(charAllowsLetterSpacing(0x0840)).toBe(false);
        // Hanifi Rohingya
        expect(charAllowsLetterSpacing(0x10d00)).toBe(false);
    });

    test('allows letter spacing of scripts whose letters stand apart', () => {
        // Hebrew, which is read right to left but is not written joined up
        expect(charAllowsLetterSpacing('ה'.codePointAt(0))).toBe(true);
        // Thaana
        expect(charAllowsLetterSpacing('ޘ'.codePointAt(0))).toBe(true);
        // Devanagari
        expect(charAllowsLetterSpacing('द'.codePointAt(0))).toBe(true);
    });
});

describe('charInComplexShapingScript', () => {
    test('recognizes that Arabic text needs complex shaping', () => {
        // Non-Arabic
        expect(charInComplexShapingScript('3'.codePointAt(0))).toBe(false);
        // Arabic
        expect(charInComplexShapingScript('۳'.codePointAt(0))).toBe(true);
        // Arabic Supplement
        expect(charInComplexShapingScript('ݣ'.codePointAt(0))).toBe(true);
        // Arabic Extended-A
        expect(charInComplexShapingScript('ࢳ'.codePointAt(0))).toBe(true);
        // Arabic Extended-B
        expect(charInComplexShapingScript('࢐'.codePointAt(0))).toBe(true);
        // Arabic Presentation Forms-A
        expect(charInComplexShapingScript('ﰤ'.codePointAt(0))).toBe(true);
        // Arabic Presentation Forms-B
        expect(charInComplexShapingScript('ﺽ'.codePointAt(0))).toBe(true);
    });
});

describe('charInRTLScript', () => {
    test('does not identify direction-neutral text as right-to-left', () => {
        expect(charInRTLScript('3'.codePointAt(0))).toBe(false);
    });

    test('identifies Arabic text as right-to-left', () => {
        // Arabic
        expect(charInRTLScript('۳'.codePointAt(0))).toBe(true);
        // Arabic Supplement
        expect(charInRTLScript('ݣ'.codePointAt(0))).toBe(true);
        // Arabic Extended-A
        expect(charInRTLScript('ࢳ'.codePointAt(0))).toBe(true);
        // Arabic Extended-B
        expect(charInRTLScript('࢐'.codePointAt(0))).toBe(true);
        // Arabic Presentation Forms-A
        expect(charInRTLScript('ﰤ'.codePointAt(0))).toBe(true);
        // Arabic Presentation Forms-B
        expect(charInRTLScript('ﺽ'.codePointAt(0))).toBe(true);
    });

    test('identifies Hebrew text as right-to-left', () => {
        // Hebrew
        expect(charInRTLScript('ה'.codePointAt(0))).toBe(true);
        // Alphabetic Presentation Forms
        expect(charInRTLScript('ﬡ'.codePointAt(0))).toBe(true);
    });

    test('identifies Thaana text as right-to-left', () => {
        // Thaana
        expect(charInRTLScript('ޘ'.codePointAt(0))).toBe(true);
    });

    test('identifies the scripts added in recent versions of the standard', () => {
        // Garay
        expect(charInRTLScript(0x10d40)).toBe(true);
        // Sidetic
        expect(charInRTLScript(0x10940)).toBe(true);
        // Old Uyghur
        expect(charInRTLScript(0x10f70)).toBe(true);
    });

    test('leaves a script the standard reads left to right alone, however it is written by hand', () => {
        // Todhri
        expect(charInRTLScript(0x105c0)).toBe(false);
        // Egyptian Hieroglyphs
        expect(charInRTLScript(0x13000)).toBe(false);
    });

    test('leaves left-to-right text alone', () => {
        expect(charInRTLScript('A'.codePointAt(0))).toBe(false);
        expect(charInRTLScript('あ'.codePointAt(0))).toBe(false);
    });
});