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// Test String.prototype.charAt with out-of-bounds indices.
function* characters(...ranges) {
for (let [start, end] of ranges) {
for (let i = start; i <= end; ++i) {
yield i;
}
}
}
const empty = [];
const ascii = [...characters(
[0x41, 0x5A], // A..Z
[0x61, 0x7A], // a..z
)];
const latin1 = [...characters(
[0xC0, 0xFF], // À..ÿ
)];
const twoByte = [...characters(
[0x100, 0x17E], // Ā..ž
)];
function atomize(s) {
return Object.keys({[s]: 0})[0];
}
function codePoints() {
return [empty, ascii, latin1, twoByte];
}
function toRope(s) {
// Ropes have at least two characters.
if (s.length < 2) {
return s;
}
if (s.length === 2) {
return newRope(s[0], s[1]);
}
return newRope(s[0], s.substring(1));
}
function makeStrings() {
let strings = codePoints()
.map(codePoints => String.fromCodePoint(...codePoints))
.flatMap(x => [
x,
toRope(x),
newString(x, {twoByte: true}),
atomize(x),
]);
return strings;
}
function testNegativeIndexConstant() {
let strings = makeStrings();
for (let i = 0; i < 200; ++i) {
let str = strings[i % strings.length];
let ch = str.charAt(-1);
assertEq(ch, "");
}
}
for (let i = 0; i < 2; ++i) {
testNegativeIndexConstant();
}
function testNegativeIndexVariable() {
let indices = [-1, -2];
let strings = makeStrings();
for (let i = 0; i < 200; ++i) {
let str = strings[i % strings.length];
let ch = str.charAt(indices[i & 1]);
assertEq(ch, "");
}
}
for (let i = 0; i < 2; ++i) {
testNegativeIndexVariable();
}
function testNegativeOrValidIndex() {
let indices = [-1, 0];
let strings = makeStrings();
// Number of string kinds created in makeStrings.
const N = 4;
let cpoints = codePoints();
assertEq(strings.length, cpoints.length * N);
for (let i = 0; i < 200; ++i) {
let str = strings[i % strings.length];
let index = indices[i & 1];
let ch = str.charAt(index);
let cp = cpoints[Math.trunc((i % strings.length) / N)];
assertEq(ch, (0 <= index && index < cp.length ? String.fromCodePoint(cp[index]) : ""));
}
}
for (let i = 0; i < 2; ++i) {
testNegativeOrValidIndex();
}
function testTooLargeIndexConstant() {
let strings = makeStrings();
for (let i = 0; i < 200; ++i) {
let str = strings[i % strings.length];
let ch = str.charAt(1000);
assertEq(ch, "");
}
}
for (let i = 0; i < 2; ++i) {
testTooLargeIndexConstant();
}
function testTooLargeIndexVariable() {
let indices = [1000, 2000];
let strings = makeStrings();
for (let i = 0; i < 200; ++i) {
let str = strings[i % strings.length];
let ch = str.charAt(indices[i & 1]);
assertEq(ch, "");
}
}
for (let i = 0; i < 2; ++i) {
testTooLargeIndexVariable();
}
function testTooLargeOrValidIndex() {
let indices = [1000, 0];
let strings = makeStrings();
// Number of string kinds created in makeStrings.
const N = 4;
let cpoints = codePoints();
assertEq(strings.length, cpoints.length * N);
for (let i = 0; i < 200; ++i) {
let str = strings[i % strings.length];
let index = indices[i & 1];
let ch = str.charAt(index);
let cp = cpoints[Math.trunc((i % strings.length) / N)];
assertEq(ch, (0 <= index && index < cp.length ? String.fromCodePoint(cp[index]) : ""));
}
}
for (let i = 0; i < 2; ++i) {
testTooLargeOrValidIndex();
}