computational-problem-solving/sat

import _parse_int from './_parse_int.js';
import _skip_blanks from './_skip_blanks.js';

/**
 * _parse_DIMACS_CNF.
 *
 * @param {Iterable<string>} iterable
 */
export default function _parse_DIMACS_CNF(iterable) {
    const iterator = iterable[Symbol.iterator]();

    const clauses = [];

    // Skip comments
    while (true) {
        const current = iterator.next();

        if (current.done) return clauses;

        const c = current.value;

        // Go to problem description
        if (c === 'p') break;

        // Skip comment
        while (true) {
            const current = iterator.next();

            if (current.done) return clauses;

            // End of comment
            if (current.value === '\n') break;
        }
    }

    // Parse problem description
    // ( we do not actually need to parse it if we suppose it is correct )

    while (true) {
        const current = iterator.next();

        if (current.done) return clauses;

        // End of description
        if (current.value === '\n') break;
    }

    // Parse problem

    // eslint-disable-next-line no-labels
    loop: while (true) {
        const clause = [];

        while (true) {
            const [done1, symbol] = _skip_blanks(iterator);
            if (done1) {
                if (clause.length > 0) clauses.push(clause);
                return clauses;
            }

            const [done2, i] = _parse_int(symbol, iterator);
            if (i === 0) {
                if (done2) return clauses;
                clauses.push(clause);
                // eslint-disable-next-line no-labels
                continue loop;
            }

            clause.push(i > 0 ? (i - 1) << 1 : ((-i - 1) << 1) | 1);

            if (done2) {
                clauses.push(clause);
                return clauses;
            }
        }
    }
}