@awayfl/avm2/lib/nat/as3ToLowerCase.ts

Virtual machine for executing AS3 code

/**
 * AS3 has a bug when converting a certain character range to lower case.
 */
export function as3ToLowerCase(value: string) {
	let chars: string [] = null;
	for (let i = 0; i < value.length; i++) {
		const charCode = value.charCodeAt(i);
		if (charCode >= 0x10A0 && charCode <= 0x10C5) {
			if (!chars) {
				chars = new Array(value.length);
			}
			chars[i] = String.fromCharCode(charCode + 48);
		}
	}
	if (chars) {
		// Fill in remaining chars if the bug needs to be emulated.
		for (let i = 0; i < chars.length; i++) {
			const char = chars[i];
			if (!char) {
				chars[i] = value.charAt(i).toLocaleString();
			}
		}
		return chars.join('');
	}
	return value.toLowerCase();
}