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- "use strict";
- Object.defineProperty(exports, "__esModule", { value: true });
- exports.parse = void 0;
- var whitespace = new Set([9, 10, 12, 13, 32]);
- var ZERO = "0".charCodeAt(0);
- var NINE = "9".charCodeAt(0);
- function parse(formula) {
- formula = formula.trim().toLowerCase();
- if (formula === "even") {
- return [2, 0];
- }
- else if (formula === "odd") {
- return [2, 1];
- }
-
- var idx = 0;
- var a = 0;
- var sign = readSign();
- var number = readNumber();
- if (idx < formula.length && formula.charAt(idx) === "n") {
- idx++;
- a = sign * (number !== null && number !== void 0 ? number : 1);
- skipWhitespace();
- if (idx < formula.length) {
- sign = readSign();
- skipWhitespace();
- number = readNumber();
- }
- else {
- sign = number = 0;
- }
- }
-
- if (number === null || idx < formula.length) {
- throw new Error("n-th rule couldn't be parsed ('" + formula + "')");
- }
- return [a, sign * number];
- function readSign() {
- if (formula.charAt(idx) === "-") {
- idx++;
- return -1;
- }
- if (formula.charAt(idx) === "+") {
- idx++;
- }
- return 1;
- }
- function readNumber() {
- var start = idx;
- var value = 0;
- while (idx < formula.length &&
- formula.charCodeAt(idx) >= ZERO &&
- formula.charCodeAt(idx) <= NINE) {
- value = value * 10 + (formula.charCodeAt(idx) - ZERO);
- idx++;
- }
-
- return idx === start ? null : value;
- }
- function skipWhitespace() {
- while (idx < formula.length &&
- whitespace.has(formula.charCodeAt(idx))) {
- idx++;
- }
- }
- }
- exports.parse = parse;
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