Repo created

libs/search/idf_map.cpp

@@ -0,0 +1,24 @@
+#include "search/idf_map.hpp"
+
+#include "base/assert.hpp"
+
+namespace search
+{
+IdfMap::IdfMap(Delegate const & delegate, double unknownIdf) : m_delegate(delegate), m_unknownIdf(unknownIdf)
+{
+  ASSERT_GREATER(m_unknownIdf, 0.0, ());
+}
+
+double IdfMap::GetImpl(Map & idfs, strings::UniString const & s, bool isPrefix)
+{
+  auto const it = idfs.find(s);
+  if (it != idfs.cend())
+    return it->second;
+
+  auto const df = static_cast<double>(m_delegate.GetNumDocs(s, isPrefix));
+  auto const idf = df == 0 ? m_unknownIdf : 1.0 / df;
+  idfs[s] = idf;
+
+  return idf;
+}
+}  // namespace search