optional support for doing perfect hashing of feature strings to save lots of memory

1 files changed, 24 insertions, 0 deletions

diff --git a/utils/perfect_hash.h b/utils/perfect_hash.h
new file mode 100644
index 00000000..8ac11f18
--- /dev/null
+++ b/utils/perfect_hash.h
@@ -0,0 +1,24 @@
+#ifndef _PERFECT_HASH_MAP_H_
+#define _PERFECT_HASH_MAP_H_
+
+#include "config.h"
+
+#ifndef HAVE_CMPH
+#error libcmph is required to use PerfectHashFunction
+#endif
+
+#include <vector>
+#include <boost/utility.hpp>
+#include "cmph.h"
+
+class PerfectHashFunction : boost::noncopyable {
+ public:
+  explicit PerfectHashFunction(const std::string& fname);
+  ~PerfectHashFunction();
+  size_t operator()(const std::string& key) const;
+  size_t number_of_keys() const;
+ private:
+  cmph_t *mphf_;
+};
+
+#endif