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