@woosh/meep-engine/src/core/parser/simple/readUnsignedIntegerToken.js

Pure JavaScript game engine. Fully featured and production ready.

import { assert } from "../../assert.js";
import DataType from "./DataType.js";
import ParserError from "./ParserError.js";
import Token from "./Token.js";

/**
 *
 * @param {string} text
 * @param {number} cursor
 * @param {number} length
 * @returns {Token}
 */
export function readUnsignedIntegerToken(text, cursor, length) {
    assert.isString(text, 'text');
    assert.isNonNegativeInteger(cursor, 'cursor');
    assert.isNonNegativeInteger(length, 'length');

    let i = cursor;

    let value = 0;

    main_loop: for (; i < length;) {
        const char = text.charAt(i);
        let digit;
        switch (char) {
            case '0':
                digit = 0;
                break;
            case '1':
                digit = 1;
                break;
            case '2':
                digit = 2;
                break;
            case '3':
                digit = 3;
                break;
            case '4':
                digit = 4;
                break;
            case '5':
                digit = 5;
                break;
            case '6':
                digit = 6;
                break;
            case '7':
                digit = 7;
                break;
            case '8':
                digit = 8;
                break;
            case '9':
                digit = 9;
                break;
            default:
                if (i === cursor) {
                    //first character is not a digit
                    throw new ParserError(i, `Expected a digit [0,1,2,3,4,5,6,7,8,9] but got '${char}' instead`, text);
                }
                //not a digit
                break main_loop;
        }
        i++;
        value = value * 10 + digit;
    }


    return new Token(value, cursor, i, "uint", DataType.Number);
}