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// Test case to cover String.prototype.substring as startsWith with a constant search string.
//
// String.prototype.substring comparison with a short (≤32 characters) constant string is
// optimised during lowering.
function* characters(...ranges) {
for (let [start, end] of ranges) {
for (let i = start; i <= end; ++i) {
yield i;
}
}
}
const ascii = [...characters(
[0x41, 0x5A], // A..Z
[0x61, 0x7A], // a..z
[0x30, 0x39], // 0..9
)];
const latin1 = [...characters(
[0xC0, 0xFF], // À..ÿ
)];
const twoByte = [...characters(
[0x100, 0x17E], // Ā..ž
)];
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 atomize(s) {
return Object.keys({[s]: 0})[0];
}
const operators = [
"==", "===", "!=", "!==",
];
for (let i = 1; i <= 32; ++i) {
let strings = [ascii, latin1, twoByte].flatMap(codePoints => [
// Same string as the input.
String.fromCodePoint(...codePoints.slice(0, i)),
// Same length as the input, but a different string.
String.fromCodePoint(...codePoints.slice(1, i + 1)),
// Shorter string than the input.
String.fromCodePoint(...codePoints.slice(0, i - 1)),
// Longer string than the input.
String.fromCodePoint(...codePoints.slice(0, i + 1)),
]).flatMap(x => [
x,
toRope(x),
newString(x, {twoByte: true}),
atomize(x),
]);
for (let codePoints of [ascii, latin1, twoByte]) {
let str = String.fromCodePoint(...codePoints.slice(0, i));
for (let op of operators) {
let fn = Function("strings", `
const expected = strings.map(x => {
// Prevent Warp compilation when computing the expected results.
with ({}) ;
return x.substring(0, ${str.length}) ${op} "${str}";
});
for (let i = 0; i < 250; ++i) {
let idx = i % strings.length;
let str = strings[idx];
let lhs = str.substring(0, ${str.length}) ${op} "${str}";
if (lhs !== expected[idx]) throw new Error();
let rhs = "${str}" ${op} str.substring(0, ${str.length});
if (rhs !== expected[idx]) throw new Error();
}
`);
fn(strings);
}
}
}
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