strings.js - mozsearch

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// for-of works on strings and String objects.

load(libdir + "string.js");

function test(s, expectedCodePoints) {

    var copy = '';

    var codepoints = 0;

    var singleHighSurrogate = false;

    for (var v of s) {

        assertEq(typeof v, 'string');

        assertEq(v.length, isSurrogatePair(v) ? 2 : 1);

        assertEq(false, singleHighSurrogate && isLowSurrogate(v));

        copy += v;

        codepoints += 1;

        singleHighSurrogate = !isSurrogatePair(v) && isHighSurrogate(v);

    assertEq(copy, String(s));

    assertEq(codepoints, expectedCodePoints);

test('', 0);

test('abc', 3);

test('a \0 \ufffe \ufeff', 7);

// Non-BMP characters are generally passed to JS in UTF-16, as surrogate pairs.

// ES6 requires that such pairs be treated as a single code point in for-of.

test('\ud808\udf45', 1);

// Also test invalid surrogate pairs:

// (1) High surrogate not followed by low surrogate

test('\ud808', 1);

test('\ud808\u0000', 2);

// (2) Low surrogate not preceded by high surrogate

test('\udf45', 1);

test('\u0000\udf45', 2);

// (3) Low surrogate followed by high surrogate

test('\udf45\ud808', 2);

test(new String(''), 0);

test(new String('abc'), 3);

test(new String('a \0 \ufffe \ufeff'), 7);

test(new String('\ud808\udf45'), 1);

test(new String('\ud808'), 1);

test(new String('\ud808\u0000'), 2);

test(new String('\udf45'), 1);

test(new String('\u0000\udf45'), 2);

test(new String('\udf45\ud808'), 2);