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15 lines
316 B
JavaScript
15 lines
316 B
JavaScript
"use strict";
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const { NoMatch } = require("../symbols");
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module.exports = function* optional(instruction, state, context) {
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let result = yield instruction.rule;
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// FIXME: NotEnoughInput handling?
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if (result === NoMatch) {
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return undefined; // TODO: Or return `null` instead?
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} else {
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return result;
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}
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};
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