333 lines
9.0 KiB
JavaScript
333 lines
9.0 KiB
JavaScript
"use strict";
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function _(message, opts) {
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return `${opts && opts.context ? opts.context : "Value"} ${message}.`;
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}
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function type(V) {
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if (V === null) {
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return "Null";
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}
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switch (typeof V) {
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case "undefined":
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return "Undefined";
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case "boolean":
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return "Boolean";
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case "number":
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return "Number";
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case "string":
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return "String";
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case "symbol":
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return "Symbol";
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case "object":
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// Falls through
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case "function":
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// Falls through
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default:
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// Per ES spec, typeof returns an implemention-defined value that is not any of the existing ones for
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// uncallable non-standard exotic objects. Yet Type() which the Web IDL spec depends on returns Object for
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// such cases. So treat the default case as an object.
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return "Object";
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}
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}
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// Round x to the nearest integer, choosing the even integer if it lies halfway between two.
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function evenRound(x) {
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// There are four cases for numbers with fractional part being .5:
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//
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// case | x | floor(x) | round(x) | expected | x <> 0 | x % 1 | x & 1 | example
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// 1 | 2n + 0.5 | 2n | 2n + 1 | 2n | > | 0.5 | 0 | 0.5 -> 0
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// 2 | 2n + 1.5 | 2n + 1 | 2n + 2 | 2n + 2 | > | 0.5 | 1 | 1.5 -> 2
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// 3 | -2n - 0.5 | -2n - 1 | -2n | -2n | < | -0.5 | 0 | -0.5 -> 0
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// 4 | -2n - 1.5 | -2n - 2 | -2n - 1 | -2n - 2 | < | -0.5 | 1 | -1.5 -> -2
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// (where n is a non-negative integer)
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//
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// Branch here for cases 1 and 4
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if ((x > 0 && (x % 1) === +0.5 && (x & 1) === 0) ||
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(x < 0 && (x % 1) === -0.5 && (x & 1) === 1)) {
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return censorNegativeZero(Math.floor(x));
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}
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return censorNegativeZero(Math.round(x));
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}
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function integerPart(n) {
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return censorNegativeZero(Math.trunc(n));
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}
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function sign(x) {
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return x < 0 ? -1 : 1;
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}
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function modulo(x, y) {
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// https://tc39.github.io/ecma262/#eqn-modulo
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// Note that http://stackoverflow.com/a/4467559/3191 does NOT work for large modulos
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const signMightNotMatch = x % y;
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if (sign(y) !== sign(signMightNotMatch)) {
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return signMightNotMatch + y;
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}
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return signMightNotMatch;
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}
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function censorNegativeZero(x) {
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return x === 0 ? 0 : x;
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}
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function createIntegerConversion(bitLength, typeOpts) {
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const isSigned = !typeOpts.unsigned;
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let lowerBound;
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let upperBound;
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if (bitLength === 64) {
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upperBound = Math.pow(2, 53) - 1;
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lowerBound = !isSigned ? 0 : -Math.pow(2, 53) + 1;
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} else if (!isSigned) {
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lowerBound = 0;
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upperBound = Math.pow(2, bitLength) - 1;
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} else {
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lowerBound = -Math.pow(2, bitLength - 1);
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upperBound = Math.pow(2, bitLength - 1) - 1;
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}
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const twoToTheBitLength = Math.pow(2, bitLength);
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const twoToOneLessThanTheBitLength = Math.pow(2, bitLength - 1);
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return (V, opts) => {
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if (opts === undefined) {
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opts = {};
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}
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let x = +V;
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x = censorNegativeZero(x); // Spec discussion ongoing: https://github.com/heycam/webidl/issues/306
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if (opts.enforceRange) {
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if (!Number.isFinite(x)) {
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throw new TypeError(_("is not a finite number", opts));
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}
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x = integerPart(x);
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if (x < lowerBound || x > upperBound) {
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throw new TypeError(_(
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`is outside the accepted range of ${lowerBound} to ${upperBound}, inclusive`, opts));
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}
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return x;
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}
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if (!Number.isNaN(x) && opts.clamp) {
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x = Math.min(Math.max(x, lowerBound), upperBound);
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x = evenRound(x);
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return x;
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}
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if (!Number.isFinite(x) || x === 0) {
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return 0;
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}
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x = integerPart(x);
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// Math.pow(2, 64) is not accurately representable in JavaScript, so try to avoid these per-spec operations if
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// possible. Hopefully it's an optimization for the non-64-bitLength cases too.
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if (x >= lowerBound && x <= upperBound) {
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return x;
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}
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// These will not work great for bitLength of 64, but oh well. See the README for more details.
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x = modulo(x, twoToTheBitLength);
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if (isSigned && x >= twoToOneLessThanTheBitLength) {
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return x - twoToTheBitLength;
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}
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return x;
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};
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}
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exports.any = V => {
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return V;
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};
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exports.void = function () {
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return undefined;
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};
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exports.boolean = function (val) {
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return !!val;
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};
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exports.byte = createIntegerConversion(8, { unsigned: false });
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exports.octet = createIntegerConversion(8, { unsigned: true });
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exports.short = createIntegerConversion(16, { unsigned: false });
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exports["unsigned short"] = createIntegerConversion(16, { unsigned: true });
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exports.long = createIntegerConversion(32, { unsigned: false });
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exports["unsigned long"] = createIntegerConversion(32, { unsigned: true });
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exports["long long"] = createIntegerConversion(64, { unsigned: false });
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exports["unsigned long long"] = createIntegerConversion(64, { unsigned: true });
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exports.double = (V, opts) => {
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const x = +V;
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if (!Number.isFinite(x)) {
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throw new TypeError(_("is not a finite floating-point value", opts));
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}
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return x;
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};
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exports["unrestricted double"] = V => {
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const x = +V;
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return x;
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};
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exports.float = (V, opts) => {
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const x = +V;
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if (!Number.isFinite(x)) {
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throw new TypeError(_("is not a finite floating-point value", opts));
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}
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if (Object.is(x, -0)) {
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return x;
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}
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const y = Math.fround(x);
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if (!Number.isFinite(y)) {
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throw new TypeError(_("is outside the range of a single-precision floating-point value", opts));
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}
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return y;
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};
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exports["unrestricted float"] = V => {
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const x = +V;
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if (isNaN(x)) {
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return x;
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}
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if (Object.is(x, -0)) {
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return x;
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}
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return Math.fround(x);
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};
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exports.DOMString = function (V, opts) {
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if (opts === undefined) {
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opts = {};
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}
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if (opts.treatNullAsEmptyString && V === null) {
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return "";
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}
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if (typeof V === "symbol") {
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throw new TypeError(_("is a symbol, which cannot be converted to a string", opts));
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}
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return String(V);
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};
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exports.ByteString = (V, opts) => {
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const x = exports.DOMString(V, opts);
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let c;
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for (let i = 0; (c = x.codePointAt(i)) !== undefined; ++i) {
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if (c > 255) {
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throw new TypeError(_("is not a valid ByteString", opts));
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}
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}
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return x;
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};
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exports.USVString = (V, opts) => {
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const S = exports.DOMString(V, opts);
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const n = S.length;
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const U = [];
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for (let i = 0; i < n; ++i) {
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const c = S.charCodeAt(i);
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if (c < 0xD800 || c > 0xDFFF) {
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U.push(String.fromCodePoint(c));
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} else if (0xDC00 <= c && c <= 0xDFFF) {
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U.push(String.fromCodePoint(0xFFFD));
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} else if (i === n - 1) {
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U.push(String.fromCodePoint(0xFFFD));
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} else {
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const d = S.charCodeAt(i + 1);
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if (0xDC00 <= d && d <= 0xDFFF) {
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const a = c & 0x3FF;
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const b = d & 0x3FF;
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U.push(String.fromCodePoint((2 << 15) + ((2 << 9) * a) + b));
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++i;
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} else {
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U.push(String.fromCodePoint(0xFFFD));
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}
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}
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}
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return U.join("");
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};
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exports.object = (V, opts) => {
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if (type(V) !== "Object") {
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throw new TypeError(_("is not an object", opts));
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}
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return V;
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};
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// Not exported, but used in Function and VoidFunction.
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// Neither Function nor VoidFunction is defined with [TreatNonObjectAsNull], so
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// handling for that is omitted.
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function convertCallbackFunction(V, opts) {
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if (typeof V !== "function") {
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throw new TypeError(_("is not a function", opts));
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}
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return V;
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}
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[
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Error,
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ArrayBuffer, // The IsDetachedBuffer abstract operation is not exposed in JS
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DataView, Int8Array, Int16Array, Int32Array, Uint8Array,
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Uint16Array, Uint32Array, Uint8ClampedArray, Float32Array, Float64Array
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].forEach(func => {
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const name = func.name;
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const article = /^[AEIOU]/.test(name) ? "an" : "a";
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exports[name] = (V, opts) => {
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if (!(V instanceof func)) {
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throw new TypeError(_(`is not ${article} ${name} object`, opts));
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}
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return V;
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};
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});
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// Common definitions
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exports.ArrayBufferView = (V, opts) => {
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if (!ArrayBuffer.isView(V)) {
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throw new TypeError(_("is not a view on an ArrayBuffer object", opts));
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}
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return V;
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};
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exports.BufferSource = (V, opts) => {
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if (!(ArrayBuffer.isView(V) || V instanceof ArrayBuffer)) {
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throw new TypeError(_("is not an ArrayBuffer object or a view on one", opts));
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}
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return V;
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};
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exports.DOMTimeStamp = exports["unsigned long long"];
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exports.Function = convertCallbackFunction;
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exports.VoidFunction = convertCallbackFunction;
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