1 files changed, 46 insertions, 0 deletions
diff --git a/extractor/matching_comparator.cc b/extractor/matching_comparator.cc
new file mode 100644
index 00000000..03db95c0
--- /dev/null
+++ b/extractor/matching_comparator.cc
@@ -0,0 +1,46 @@
+#include "matching_comparator.h"
+
+#include "matching.h"
+#include "vocabulary.h"
+
+MatchingComparator::MatchingComparator(int min_gap_size, int max_rule_span) :
+    min_gap_size(min_gap_size), max_rule_span(max_rule_span) {}
+
+int MatchingComparator::Compare(const Matching& left,
+                                const Matching& right,
+                                int last_chunk_len,
+                                bool offset) const {
+  if (left.sentence_id != right.sentence_id) {
+    return left.sentence_id < right.sentence_id ? -1 : 1;
+  }
+
+  if (left.positions.size() == 1 && right.positions.size() == 1) {
+    // The prefix and the suffix must be separated by a non-terminal, otherwise
+    // we would be doing a suffix array lookup.
+    if (right.positions[0] - left.positions[0] <= min_gap_size) {
+      return 1;
+    }
+  } else if (offset) {
+    for (size_t i = 1; i < left.positions.size(); ++i) {
+      if (left.positions[i] != right.positions[i - 1]) {
+        return left.positions[i] < right.positions[i - 1] ? -1 : 1;
+      }
+    }
+  } else {
+    if (left.positions[0] + 1 != right.positions[0]) {
+      return left.positions[0] + 1 < right.positions[0] ? -1 : 1;
+    }
+    for (size_t i = 1; i < left.positions.size(); ++i) {
+      if (left.positions[i] != right.positions[i]) {
+        return left.positions[i] < right.positions[i] ? -1 : 1;
+      }
+    }
+  }
+
+  if (right.positions.back() + last_chunk_len - left.positions.front() >
+      max_rule_span) {
+    return -1;
+  }
+
+  return 0;
+}