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// Copyright (C) 2022 André Bargull. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-string.prototype.substr
description: >
Test String.prototype.substr with number inputs for start and length.
---*/
function ToIntegerOrInfinity(arg) {
assert.sameValue(typeof arg, "number");
return Number.isNaN(arg) ? 0 : Math.trunc(arg);
}
// Basic reference implementation. Expects all inputs have the correct type.
function StringSubstr(string, start, length) {
// Steps 1-2.
assert.sameValue(typeof string, "string");
// Step 3.
let size = string.length;
// Step 4.
let intStart = ToIntegerOrInfinity(start);
// Steps 5-7.
if (intStart === -Infinity) {
intStart = 0;
} else if (intStart < 0) {
intStart = Math.max(size + intStart, 0);
} else {
intStart = Math.min(intStart, size)
}
// |0 <= intStart <= size| now holds.
assert(0 <= intStart && intStart <= size);
// Step 8.
let intLength = length === undefined ? size : ToIntegerOrInfinity(length);
// Step 9.
intLength = Math.min(Math.max(intLength, 0), size);
// |0 <= intLength <= size| now holds.
assert(0 <= intLength && intLength <= size);
// Step 10.
let intEnd = Math.min(intStart + intLength, size);
// |intStart <= intEnd <= size| now holds.
assert(intStart <= intEnd && intEnd <= size);
// Step 11.
//
// Call `substring` and check the result is correct.
let result = string.substring(intStart, intEnd);
assert.sameValue(result.length, intEnd - intStart);
for (let i = 0; i < result.length; ++i) {
assert.sameValue(result[i], string[intStart + i]);
}
return result;
}
const positiveIntegers = [
0, 1, 2, 3, 4, 5, 10, 100,
];
const integers = [
...positiveIntegers,
...positiveIntegers.map(v => -v),
];
const numbers = [
...integers,
...integers.map(v => v + 0.5),
-Infinity, Infinity, NaN,
];
for (let string of ["", "a", "ab", "abc"]) {
for (let start of numbers) {
for (let length of [...numbers, undefined]) {
let actual = string.substr(start, length);
let expected = StringSubstr(string, start, length);
assert.sameValue(actual, expected, `"${string}".substr(${start}, ${length})`);
}
}
}
reportCompare(0, 0);
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