Makes RocksDB dependency optional

lib/Cargo.toml

@@ -16,7 +16,7 @@ travis-ci = { repository = "Tpt/rudf" }
 
 [dependencies]
 lazy_static = "1"
-rocksdb = "0.10"
+rocksdb = { version = "0.10", optional = true }
 url = "1"
 uuid = { version = "0.7", features = ["v4"] }
 bzip2 = "0.3"

lib/src/lib.rs

@@ -39,6 +39,7 @@ extern crate language_tags;
 extern crate num_traits;
 extern crate ordered_float;
 extern crate quick_xml;
+#[cfg(feature = "rocksdb")]
 extern crate rocksdb;
 extern crate rust_decimal;
 extern crate url;

lib/src/store/mod.rs

@@ -4,8 +4,10 @@ pub(crate) mod encoded;
 pub mod isomorphism;
 mod memory;
 pub(crate) mod numeric_encoder;
+#[cfg(feature = "rocksdb")]
 mod rocksdb;
 
 pub use store::memory::MemoryDataset;
 pub use store::memory::MemoryGraph;
+#[cfg(feature = "rocksdb")]
 pub use store::rocksdb::RocksDbDataset;