예제 #1
0
파일: FTWords.java 프로젝트: jefferya/basex
  @Override
  public boolean indexAccessible(final IndexInfo ii) {
    /* If the following conditions yield true, the index is accessed:
     * - all query terms are statically available
     * - no FTTimes option is specified
     * - explicitly set case, diacritics and stemming match options do not
     *   conflict with index options. */
    data = ii.ic.data;
    final MetaData md = data.meta;
    final FTOpt fto = ftt.opt;

    /* Index will be applied if no explicit match options have been set
     * that conflict with the index options. As a consequence, though, index-
     * based querying might yield other results than sequential scanning. */
    if (occ != null
        || fto.cs != null && md.casesens == (fto.cs == FTCase.INSENSITIVE)
        || fto.isSet(DC) && md.diacritics != fto.is(DC)
        || fto.isSet(ST) && md.stemming != fto.is(ST)
        || fto.ln != null && !fto.ln.equals(md.language)) return false;

    // adopt database options to tokenizer
    fto.copy(md);

    // estimate costs if text is not known at compile time
    if (tokens == null) {
      ii.costs = Math.max(2, data.meta.size / 30);
      return true;
    }

    // summarize number of hits; break loop if no hits are expected
    final FTLexer ft = new FTLexer(fto);
    ii.costs = 0;
    for (byte[] t : tokens) {
      ft.init(t);
      while (ft.hasNext()) {
        final byte[] tok = ft.nextToken();
        if (fto.sw != null && fto.sw.contains(tok)) continue;

        if (fto.is(WC)) {
          // don't use index if one of the terms starts with a wildcard
          t = ft.get();
          if (t[0] == '.') return false;
          // don't use index if certain characters or more than 1 dot are found
          int d = 0;
          for (final byte w : t) {
            if (w == '{' || w == '\\' || w == '.' && ++d > 1) return false;
          }
        }
        // favor full-text index requests over exact queries
        final int costs = data.costs(ft);
        if (costs != 0) ii.costs += Math.max(2, costs / 100);
      }
    }
    return true;
  }
예제 #2
0
파일: FTWords.java 프로젝트: jefferya/basex
  /**
   * Returns a scan-based index iterator.
   *
   * @param lex lexer, including the queried value
   * @return node iterator
   * @throws QueryException query exception
   */
  private FTIndexIterator scan(final FTLexer lex) throws QueryException {
    final FTLexer input = new FTLexer(ftt.opt);
    final FTTokens fttokens = ftt.cache(lex.get());

    return new FTIndexIterator() {
      final int sz = data.meta.size;
      int pre = -1, ps;

      @Override
      public int pre() {
        return pre;
      }

      @Override
      public boolean more() {
        while (++pre < sz) {
          if (data.kind(pre) != Data.TEXT) continue;
          input.init(data.text(pre, true));
          matches.reset(ps);
          try {
            if (ftt.contains(fttokens, input) != 0) return true;
          } catch (final QueryException ignore) {
            // ignore exceptions
          }
        }
        return false;
      }

      @Override
      public FTMatches matches() {
        return matches;
      }

      @Override
      public void pos(final int p) {
        ps = p;
      }

      @Override
      public int size() {
        // worst case
        return Math.max(1, sz >>> 1);
      }
    };
  }