Function findMatchingOpenParenOffset

packages/queryLanguage/src/tokens.ts:304–335

* Finds the offset of the '(' that matches the current ')' at offset 0. * Handles escaped characters (backslash followed by any character).

(input: InputStream)

 * Handles escaped characters (backslash followed by any character).
 */
function findMatchingOpenParenOffset(input: InputStream): number | null {
    if (input.next !== CLOSE_PAREN) {
        return null;
    }

    let offset = -1;
    let depth = 1;

    while (true) {
        const ch = input.peek(offset);

        if (ch === EOF) {
            return null;
        }

        if (isEscapedAt(input, offset)) {
            offset--;
            continue;
        }

        if (ch === CLOSE_PAREN) {
            depth++;
        } else if (ch === OPEN_PAREN) {
            depth--;
            if (depth === 0) {
                return offset;
            }
        }

        offset--;
    }
}

/**
 * Checks if we're currently inside a ParenExpr by looking backwards in the input