swc/scripts/sourcemap/vlq.js
2022-05-04 14:25:28 +00:00

108 lines
2.6 KiB
JavaScript

(function (global, factory) {
typeof exports === "object" && typeof module !== "undefined"
? factory(exports)
: typeof define === "function" && define.amd
? define(["exports"], factory)
: ((global =
typeof globalThis !== "undefined" ? globalThis : global || self),
factory((global.vlq = {})));
})(this, function (exports) {
"use strict";
/** @type {Record<string, number>} */
let char_to_integer = {};
/** @type {Record<number, string>} */
let integer_to_char = {};
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
.split("")
.forEach(function (char, i) {
char_to_integer[char] = i;
integer_to_char[i] = char;
});
/** @param {string} string */
function decode(string) {
/** @type {number[]} */
let result = [];
let shift = 0;
let value = 0;
for (let i = 0; i < string.length; i += 1) {
let integer = char_to_integer[string[i]];
if (integer === undefined) {
throw new Error("Invalid character (" + string[i] + ")");
}
const has_continuation_bit = integer & 32;
integer &= 31;
value += integer << shift;
if (has_continuation_bit) {
shift += 5;
} else {
const should_negate = value & 1;
value >>>= 1;
if (should_negate) {
result.push(value === 0 ? -0x80000000 : -value);
} else {
result.push(value);
}
// reset
value = shift = 0;
}
}
return result;
}
/** @param {number | number[]} value */
function encode(value) {
if (typeof value === "number") {
return encode_integer(value);
}
let result = "";
for (let i = 0; i < value.length; i += 1) {
result += encode_integer(value[i]);
}
return result;
}
/** @param {number} num */
function encode_integer(num) {
let result = "";
if (num < 0) {
num = (-num << 1) | 1;
} else {
num <<= 1;
}
do {
let clamped = num & 31;
num >>>= 5;
if (num > 0) {
clamped |= 32;
}
result += integer_to_char[clamped];
} while (num > 0);
return result;
}
exports.decode = decode;
exports.encode = encode;
Object.defineProperty(exports, "__esModule", { value: true });
});