From 38a5bee71f6b49515cd105a9467ff602ff9dee64 Mon Sep 17 00:00:00 2001 From: Chris Dyer Date: Tue, 13 Sep 2011 13:25:46 +0100 Subject: optional support for doing perfect hashing of feature strings to save lots of memory --- utils/perfect_hash.cc | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 utils/perfect_hash.cc (limited to 'utils/perfect_hash.cc') diff --git a/utils/perfect_hash.cc b/utils/perfect_hash.cc new file mode 100644 index 00000000..706e2741 --- /dev/null +++ b/utils/perfect_hash.cc @@ -0,0 +1,37 @@ +#include "config.h" + +#ifdef HAVE_CMPH + +#include "perfect_hash.h" + +#include +#include + +using namespace std; + +PerfectHashFunction::~PerfectHashFunction() { + cmph_destroy(mphf_); +} + +PerfectHashFunction::PerfectHashFunction(const string& fname) { + FILE* f = fopen(fname.c_str(), "r"); + if (!f) { + cerr << "Failed to open file " << fname << " for reading: cannot load hash function.\n"; + abort(); + } + mphf_ = cmph_load(f); + if (!mphf_) { + cerr << "cmph_load failed on " << fname << "!\n"; + abort(); + } +} + +size_t PerfectHashFunction::operator()(const string& key) const { + return cmph_search(mphf_, &key[0], key.size()); +} + +size_t PerfectHashFunction::number_of_keys() const { + return cmph_size(mphf_); +} + +#endif -- cgit v1.2.3