finitedomain/src/propagators/neq.js

A fast feature rich finite domain solver

import {
  LOG_FLAG_PROPSTEPS,
  NO_SUCH_VALUE,

  ASSERT,
  ASSERT_LOG,
  ASSERT_NORDOM,
} from '../helpers';
import {
  domain__debug,
  domain_createEmpty,
  domain_getValue,
  domain_removeValue,
} from '../domain';

// BODY_START

/**
 * @param {$space} space
 * @param {$config} config
 * @param {number} varIndex1
 * @param {number} varIndex2
 */
function propagator_neqStepBare(space, config, varIndex1, varIndex2) {
  ASSERT(space && space._class === '$space', 'SHOULD_GET_SPACE');
  ASSERT(typeof varIndex1 === 'number', 'VAR_INDEX_SHOULD_BE_NUMBER');
  ASSERT(typeof varIndex2 === 'number', 'VAR_INDEX_SHOULD_BE_NUMBER');

  let vardoms = space.vardoms;
  let domain1 = vardoms[varIndex1];
  let domain2 = vardoms[varIndex2];

  ASSERT_NORDOM(domain1);
  ASSERT_NORDOM(domain2);
  ASSERT(domain1 && domain2, 'SHOULD_NOT_BE_REJECTED');

  // remove solved value from the other domain. confirm neither rejects over it.
  let value = domain_getValue(domain1);
  if (value !== NO_SUCH_VALUE) {
    if (domain1 === domain2) {
      vardoms[varIndex1] = domain_createEmpty();
      vardoms[varIndex2] = domain_createEmpty();
    } else {
      vardoms[varIndex2] = domain_removeValue(domain2, value);
    }
  } else {
    // domain1 is not solved, remove domain2 from domain1 if domain2 is solved
    value = domain_getValue(domain2);
    if (value !== NO_SUCH_VALUE) {
      vardoms[varIndex1] = domain_removeValue(domain1, value);
    }
  }

  ASSERT_LOG(LOG_FLAG_PROPSTEPS, log => log('propagator_neqStepBare; indexes:', varIndex1, varIndex2, 'doms:', domain__debug(domain1), 'neq', domain__debug(domain2), '->', domain__debug(vardoms[varIndex1]), domain__debug(vardoms[varIndex2])));
  ASSERT_NORDOM(space.vardoms[varIndex1], true, domain__debug);
  ASSERT_NORDOM(space.vardoms[varIndex2], true, domain__debug);
}

/**
 * neq will only reject if both domains are solved and equal.
 * This is a read-only check.
 *
 * @param {$domain} domain1
 * @param {$domain} domain2
 * @returns {boolean}
 */
function propagator_neqStepWouldReject(domain1, domain2) {
  let value = domain_getValue(domain1);
  let result = value !== NO_SUCH_VALUE && value === domain_getValue(domain2);
  ASSERT_LOG(LOG_FLAG_PROPSTEPS, log => log('propagator_neqStepWouldReject;', domain__debug(domain1), '===', domain__debug(domain2), '->', result));
  return result;
}

// BODY_STOP

export {
  propagator_neqStepBare,
  propagator_neqStepWouldReject,
};