export interface Pos {
    line: number;
    column: number;
    pos: number;
    name: string | null;
    fixed?: boolean;
}

export function startPos(name: string | null): Pos {
    return { line: 1, column: 0, pos: 0, name };
}

export function fixPos(p: Pos): Pos {
    return { ... p, fixed: true };
}

export function advancePos(p: Pos, ch: string): boolean {
    if (p.fixed ?? false) {
        return ch === '\n';
    } else {
        let advancedLine = false;
        p.pos++;
        switch (ch) {
            case '\t':
                p.column = (p.column + 8) & ~7;
                break;
            case '\n':
                p.column = 0;
                p.line++;
                advancedLine = true;
                break;
            case '\r':
                p.column = 0;
                break;
            default:
                p.column++;
                break;
        }
        return advancedLine;
    }
}