Rust-PHF is a library to generate efficient lookup tables at compile time using perfect hash functions.
It currently uses the
CHD algorithm and can generate
a 100,000 entry map in roughly .4 seconds. By default statistics are not
produced, but if you set the environment variable PHF_STATS
it will issue
a compiler note about how long it took.
MSRV (minimum supported rust version) is Rust 1.46.
Usage
PHF data structures can be constructed via either the procedural
macros in the phf_macros
crate or code generation supported by the
phf_codegen
crate. If you prefer macros, you can easily use them by
enabling the macros
feature of the phf
crate, like:
[]
= { = "0.10", = ["macros"] }
To compile the phf
crate with a dependency on
libcore instead of libstd, enabling use in environments where libstd
will not work, set default-features = false
for the dependency:
[]
# to use `phf` in `no_std` environments
= { = "0.10", = false }
Example (with the macros
feature enabled)
use phf_map;
static KEYWORDS: Map = phf_map! ;
Alternatively, you can use the phf_codegen
crate to generate PHF datatypes
in a build script.
Note
Currently, the macro syntax has some limitations and may not work as you want. See #183 or #196 for example.