extensions/php-language-features/src/features/signatureHelpProvider.ts/BackwardIterator/next
class BackwardIterator:	public next(): number {
		if (this.offset < 0) {
			if (this.lineNumber > 0) {
				this.lineNumber--;
				this.line = this.model.lineAt(this.lineNumber).text;
				this.offset = this.line.length - 1;
				return _NL;
			}
			this.lineNumber = -1;
			return BOF;
		}
		let ch = this.line.charCodeAt(this.offset);
		this.offset--;
		return ch;
	}