1 files changed, 28 insertions, 0 deletions
diff --git a/gi/pf/reachability.h b/gi/pf/reachability.h
new file mode 100644
index 00000000..98450ec1
--- /dev/null
+++ b/gi/pf/reachability.h
@@ -0,0 +1,28 @@
+#ifndef _REACHABILITY_H_
+#define _REACHABILITY_H_
+
+#include "boost/multi_array.hpp"
+
+// determines minimum and maximum lengths of outgoing edges from all
+// coverage positions such that the alignment path respects src and
+// trg maximum phrase sizes
+//
+// runs in O(n^2 * src_max * trg_max) time but should be relatively fast
+//
+// currently forbids 0 -> n and n -> 0 alignments
+
+struct Reachability {
+  boost::multi_array<bool, 4> edges;  // edges[src_covered][trg_covered][x][trg_delta] is this edge worth exploring?
+  boost::multi_array<short, 2> max_src_delta; // msd[src_covered][trg_covered] -- the largest src delta that's valid
+
+  Reachability(int srclen, int trglen, int src_max_phrase_len, int trg_max_phrase_len) :
+      edges(boost::extents[srclen][trglen][src_max_phrase_len+1][trg_max_phrase_len+1]),
+      max_src_delta(boost::extents[srclen][trglen]) {
+    ComputeReachability(srclen, trglen, src_max_phrase_len, trg_max_phrase_len);
+  }
+
+ private:
+  void ComputeReachability(int srclen, int trglen, int src_max_phrase_len, int trg_max_phrase_len);
+};
+
+#endif