tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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string-at.js (2940B)

      1 // Test String.prototype.at with negative and non-negative indices.
      2 
      3 function* characters(...ranges) {
      4  for (let [start, end] of ranges) {
      5    for (let i = start; i <= end; ++i) {
      6      yield i;
      7    }
      8  }
      9 }
     10 
     11 const empty = [];
     12 
     13 const ascii = [...characters(
     14  [0x41, 0x5A], // A..Z
     15  [0x61, 0x7A], // a..z
     16 )];
     17 
     18 const latin1 = [...characters(
     19  [0xC0, 0xFF], // À..ÿ
     20 )];
     21 
     22 const twoByte = [...characters(
     23  [0x100, 0x17E], // Ā..ž
     24 )];
     25 
     26 function atomize(s) {
     27  return Object.keys({[s]: 0})[0];
     28 }
     29 
     30 function codePoints() {
     31  return [empty, ascii, latin1, twoByte];
     32 }
     33 
     34 function toRope(s) {
     35  // Ropes have at least two characters.
     36  if (s.length < 2) {
     37    return s;
     38  }
     39  if (s.length === 2) {
     40    return newRope(s[0], s[1]);
     41  }
     42  return newRope(s[0], s.substring(1));
     43 }
     44 
     45 function makeStrings() {
     46  let strings = codePoints()
     47  .map(codePoints => String.fromCodePoint(...codePoints))
     48  .flatMap(x => [
     49    x,
     50    toRope(x),
     51    newString(x, {twoByte: true}),
     52    atomize(x),
     53  ]);
     54  return strings;
     55 }
     56 
     57 function testNonNegativeIndexConstant() {
     58  let strings = makeStrings();
     59  for (let i = 0; i < 200; ++i) {
     60    let str = strings[i % strings.length];
     61    let index = 0;
     62    let ch = str.at(index);
     63    let expected = str.charAt(index);
     64    if (expected === "") expected = undefined;
     65    assertEq(ch, expected);
     66  }
     67 }
     68 for (let i = 0; i < 2; ++i) {
     69  testNonNegativeIndexConstant();
     70 }
     71 
     72 function testNonNegativeIndex() {
     73  let strings = makeStrings();
     74  for (let i = 0; i < 200; ++i) {
     75    let str = strings[i % strings.length];
     76    let index = i & 3;
     77    let ch = str.at(index);
     78    let expected = str.charAt(index);
     79    if (expected === "") expected = undefined;
     80    assertEq(ch, expected);
     81  }
     82 }
     83 for (let i = 0; i < 2; ++i) {
     84  testNonNegativeIndex();
     85 }
     86 
     87 function testNegativeIndexConstant() {
     88  let strings = makeStrings();
     89  for (let i = 0; i < 200; ++i) {
     90    let str = strings[i % strings.length];
     91    let index = -1;
     92    let ch = str.at(index);
     93    let expected = str.charAt(str.length + index);
     94    if (expected === "") expected = undefined;
     95    assertEq(ch, expected);
     96  }
     97 }
     98 for (let i = 0; i < 2; ++i) {
     99  testNegativeIndexConstant();
    100 }
    101 
    102 function testNegativeIndex() {
    103  let strings = makeStrings();
    104  for (let i = 0; i < 200; ++i) {
    105    let str = strings[i % strings.length];
    106    let index = -(i & 3) - 1;
    107    let ch = str.at(index);
    108    let expected = str.charAt(str.length + index);
    109    if (expected === "") expected = undefined;
    110    assertEq(ch, expected);
    111  }
    112 }
    113 for (let i = 0; i < 2; ++i) {
    114  testNegativeIndex();
    115 }
    116 
    117 function testAbsentIndex() {
    118  let strings = makeStrings();
    119  for (let i = 0; i < 200; ++i) {
    120    let str = strings[i % strings.length];
    121    let index = 0;
    122    let ch = str.at(/* ToInteger(ToNumber(undefined)) = ToInteger(NaN) = 0 */);
    123    let expected = str.charAt(index);
    124    if (expected === "") expected = undefined;
    125    assertEq(ch, expected);
    126  }
    127 }
    128 for (let i = 0; i < 2; ++i) {
    129  testAbsentIndex();
    130 }