Add some assertions and PHOBIC typedef

include/dense_partitioned_phf.hpp

@@ -7,13 +7,17 @@ namespace pthash {
 template <typename Hasher, typename Bucketer, typename Encoder, bool NeedsFreeArray,
           pthash_search_type Search>
 struct dense_partitioned_phf {
+    static_assert(std::is_base_of<dense_encoder, Encoder>::value,
+                  "Needs a dense encoder for dense partitioned PTHash. Select another encoder.");
     typedef Encoder encoder_type;
     static constexpr bool needsFreeArray = NeedsFreeArray;
 
     template <typename Iterator>
     build_timings build_in_internal_memory(Iterator keys, const uint64_t num_keys,
                                            build_configuration const& config) {
         assert(Search == config.search);
+        assert(config.dense_partitioning == true);
+        assert(config.avg_partition_size < 10000); // Unlike partitioned, must use small partitions
         internal_memory_builder_partitioned_phf<Hasher, Bucketer> builder;
         auto timings = builder.build_from_keys(keys, num_keys, config);
         timings.encoding_microseconds = build(builder, config);
@@ -132,4 +136,7 @@ struct dense_partitioned_phf {
     ef_sequence<false> m_free_slots;
 };
 
+template <typename Hasher, typename Encoder>
+using phobic = dense_partitioned_phf<Hasher, table_bucketer<opt_bucketer>,
+    dense_interleaved<Encoder>, false, pthash_search_type::add_displacement>;
 }  // namespace pthash

include/encoders/dense_encoders.hpp

@@ -49,8 +49,11 @@ struct diff {
     Encoder m_encoder;
 };
 
+struct dense_encoder {
+};
+
 template <typename Encoder>
-struct dense_mono {
+struct dense_mono : dense_encoder {
     template <typename Iterator>
     void encode(Iterator begin,                            //
                 const uint64_t num_partitions,             //
@@ -89,7 +92,7 @@ struct dense_mono {
 };
 
 template <typename Encoder>
-struct dense_interleaved {
+struct dense_interleaved : dense_encoder {
     template <typename Iterator>
     void encode(Iterator begin,                            //
                 const uint64_t num_partitions,             //
@@ -151,7 +154,7 @@ struct dense_interleaved {
 };
 
 template <typename Front, typename Back, uint64_t numerator = 1, uint64_t denominator = 3>
-struct dense_dual {
+struct dense_dual : dense_encoder {
     template <typename Iterator>
     void encode(Iterator begin,                            //
                 const uint64_t num_partitions,             //

include/partitioned_phf.hpp

@@ -10,6 +10,8 @@ namespace pthash {
 template <typename Hasher, typename Bucketer, typename Encoder, bool Minimal,
           pthash_search_type Search>
 struct partitioned_phf {
+    static_assert(!std::is_base_of<dense_encoder, Encoder>::value,
+                  "Dense encoders are only for dense PTHash. Select another encoder.");
 private:
     struct partition {
         template <typename Visitor>

include/single_phf.hpp

@@ -9,6 +9,8 @@ namespace pthash {
 template <typename Hasher, typename Bucketer, typename Encoder, bool Minimal,
           pthash_search_type Search>
 struct single_phf {
+    static_assert(!std::is_base_of<dense_encoder, Encoder>::value,
+                  "Dense encoders are only for dense PTHash. Select another encoder.");
     typedef Encoder encoder_type;
     static constexpr bool minimal = Minimal;