1 files changed, 96 insertions, 0 deletions
diff --git a/storage/mroonga/vendor/groonga/lib/scorers.c b/storage/mroonga/vendor/groonga/lib/scorers.c
new file mode 100644
index 00000000..44a3e9b4
--- /dev/null
+++ b/storage/mroonga/vendor/groonga/lib/scorers.c
@@ -0,0 +1,96 @@
+/* -*- c-basic-offset: 2 -*- */
+/*
+  Copyright(C) 2015 Brazil
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License version 2.1 as published by the Free Software Foundation.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA
+*/
+
+#include "grn_db.h"
+
+#include <groonga/scorer.h>
+
+#include <math.h>
+
+static double
+scorer_tf_idf(grn_ctx *ctx, grn_scorer_matched_record *record)
+{
+  double min_score = 1.0;
+  double tf;
+  double n_all_documents;
+  double n_candidates;
+  double n_tokens;
+  double n_estimated_match_documents;
+
+  tf = grn_scorer_matched_record_get_n_occurrences(ctx, record) +
+    grn_scorer_matched_record_get_total_term_weights(ctx, record);
+  n_all_documents = grn_scorer_matched_record_get_n_documents(ctx, record);
+  n_candidates = grn_scorer_matched_record_get_n_candidates(ctx, record);
+  n_tokens = grn_scorer_matched_record_get_n_tokens(ctx, record);
+  n_estimated_match_documents = n_candidates / n_tokens;
+
+  if (n_estimated_match_documents >= n_all_documents) {
+    return min_score;
+  } else {
+    double idf;
+    double tf_idf;
+
+    idf = log(n_all_documents / n_estimated_match_documents);
+    tf_idf = tf * idf;
+    return fmax(tf_idf, min_score);
+  }
+}
+
+static double
+scorer_tf_at_most(grn_ctx *ctx, grn_scorer_matched_record *record)
+{
+  double tf;
+  double max;
+  grn_obj *max_raw;
+
+  tf = grn_scorer_matched_record_get_n_occurrences(ctx, record) +
+    grn_scorer_matched_record_get_total_term_weights(ctx, record);
+  max_raw = grn_scorer_matched_record_get_arg(ctx, record, 0);
+
+  if (!max_raw) {
+    return tf;
+  }
+
+  if (max_raw->header.type != GRN_BULK) {
+    return tf;
+  }
+
+  if (max_raw->header.domain == GRN_DB_FLOAT) {
+    max = GRN_FLOAT_VALUE(max_raw);
+  } else {
+    grn_obj casted_max_raw;
+    GRN_FLOAT_INIT(&casted_max_raw, 0);
+    if (grn_obj_cast(ctx, max_raw, &casted_max_raw, GRN_FALSE) != GRN_SUCCESS) {
+      GRN_OBJ_FIN(ctx, &casted_max_raw);
+      return tf;
+    } else {
+      max = GRN_FLOAT_VALUE(&casted_max_raw);
+    }
+    GRN_OBJ_FIN(ctx, &casted_max_raw);
+  }
+
+  return fmin(tf, max);
+}
+
+grn_rc
+grn_db_init_builtin_scorers(grn_ctx *ctx)
+{
+  grn_scorer_register(ctx, "scorer_tf_idf", -1, scorer_tf_idf);
+  grn_scorer_register(ctx, "scorer_tf_at_most", -1, scorer_tf_at_most);
+  return GRN_SUCCESS;
+}