parseSearchQuery static method

List<QueryTerm> parseSearchQuery(String query)

Parses query into a list of QueryTerm (words/phrases, AND/OR, minus).

Implementation

static List<QueryTerm> parseSearchQuery(String query) {
  final String q = query.trim();
  final RegExp quoted = RegExp(r'"([^"]*)"');
  final RegExp ws = RegExp(r'\s+');
  int pos = 0;
  // Upper bound on term count: every character could in theory start a new
  // single-char term, so length+1 slots can never overflow. Pre-filling avoids
  // per-add growth and the trailing slots are dropped by the final sublist.
  final int maxTerms = query.length + 1;
  final List<QueryTerm> out = List.filled(maxTerms, QueryTerm(''));
  int outIndex = 0;
  // Walk the quoted phrases in order; the gap before each match (pos..m.start)
  // is bare text that gets word-split, and the captured group is one phrase term.
  for (final Match m in quoted.allMatches(q)) {
    if (m.start > pos) {
      final int end = m.start.clamp(0, q.length);
      final int start = pos.clamp(0, end);
      final String span = start < end ? q.substringSafe(start, end) : '';
      for (final String word in span.split(ws).where((String x) => x.isNotEmpty)) {
        // "OR" is dropped, not emitted as a term: this parser treats every gap
        // between terms as AND, so the explicit OR keyword is a no-op separator.
        if (word.toUpperCase() != 'OR') {
          // Strip the leading '-' from the stored text (consistent with the
          // trailing-words branch below); the negation is captured separately.
          final String term = word.startsWith('-') ? word.replaceRange(0, 1, '') : word;
          out[outIndex++] = QueryTerm(term, isNegated: word.startsWith('-'));
        }
      }
    }
    final String phrase = m.group(1) ?? '';
    if (phrase.isNotEmpty) {
      out[outIndex++] = QueryTerm(phrase);
    }
    pos = m.end;
  }
  final int restStart = pos.clamp(0, q.length);
  final String rest = restStart < q.length ? q.substringSafe(restStart) : '';
  for (final String word in rest.split(ws).where((String x) => x.isNotEmpty)) {
    if (word.toUpperCase() != 'OR') {
      final String term = word.startsWith('-') ? word.replaceRange(0, 1, '') : word;
      out[outIndex++] = QueryTerm(term, isNegated: word.startsWith('-'));
    }
  }
  return out.sublist(0, outIndex);
}