getConflictingAltSubsets static method

List<BitSet> getConflictingAltSubsets(ATNConfigSet configs)

This function gets the conflicting alt subsets from a configuration set. For each configuration c in configs:

map[c] U= c.{@link ATNConfig#alt alt} # map hash/equals uses s and x, not
alt and not pred

Implementation

static List<BitSet> getConflictingAltSubsets(ATNConfigSet configs) {
  final configToAlts =
      HashMap<ATNConfig, BitSet>(equals: (ATNConfig? a, ATNConfig? b) {
    if (identical(a, b)) return true;
    if (a == null || b == null) return false;
    return a.state.stateNumber == b.state.stateNumber &&
        a.context == b.context;
  }, hashCode: (ATNConfig o) {
    /**
     * The hash code is only a function of the {@link ATNState#stateNumber}
     * and {@link ATNConfig#context}.
     */
    var hashCode = MurmurHash.initialize(7);
    hashCode = MurmurHash.update(hashCode, o.state.stateNumber);
    hashCode = MurmurHash.update(hashCode, o.context);
    hashCode = MurmurHash.finish(hashCode, 2);
    return hashCode;
  });
  for (var c in configs) {
    var alts = configToAlts[c];
    if (alts == null) {
      alts = BitSet();
      configToAlts[c] = alts;
    }
    alts.set(c.alt);
  }
  return configToAlts.values.toList();
}