challenge-algorithms-v2.0-s.../node_modules/@jridgewell/set-array/dist/set-array.mjs

49 lines
1.4 KiB
JavaScript

/**
* Gets the index associated with `key` in the backing array, if it is already present.
*/
let get;
/**
* Puts `key` into the backing array, if it is not already present. Returns
* the index of the `key` in the backing array.
*/
let put;
/**
* Pops the last added item out of the SetArray.
*/
let pop;
/**
* SetArray acts like a `Set` (allowing only one occurrence of a string `key`), but provides the
* index of the `key` in the backing array.
*
* This is designed to allow synchronizing a second array with the contents of the backing array,
* like how in a sourcemap `sourcesContent[i]` is the source content associated with `source[i]`,
* and there are never duplicates.
*/
class SetArray {
constructor() {
this._indexes = { __proto__: null };
this.array = [];
}
}
(() => {
get = (strarr, key) => strarr._indexes[key];
put = (strarr, key) => {
// The key may or may not be present. If it is present, it's a number.
const index = get(strarr, key);
if (index !== undefined)
return index;
const { array, _indexes: indexes } = strarr;
return (indexes[key] = array.push(key) - 1);
};
pop = (strarr) => {
const { array, _indexes: indexes } = strarr;
if (array.length === 0)
return;
const last = array.pop();
indexes[last] = undefined;
};
})();
export { SetArray, get, pop, put };
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