Allows for long string or data constants to be compressed at compile-time, with a small decoder routine for decompression at run-time.
Allows for long strings of text or data to be compressed at compile-time, with an efficient decoder routine for decompression at run-time. The decoder conforms to `std::forward_iterator`, allowing for use in ranged-for or standard algorithms.
Compression is achieved using [Huffman coding](https://en.wikipedia.org/wiki/Huffman_coding), which works by creating short (measured in bits) codes for frequently-occuring characters.
Compression is achieved using [Huffman coding](https://en.wikipedia.org/wiki/Huffman_coding), which works by creating short codes (measured in bits) for frequently-occuring characters. This works best on larger pieces of data, or more so data that is limited in its range of values (e.g. written text).
## Use cases
## Use cases
**1. Text configurations (e.g. JSON)**
**1. Text configurations (e.g. JSON)**
A ~3.5kB string of JSON can be compressed down ~2.5kB ([see it on Godbolt](https://godbolt.org/z/P6a9Kr)).
A ~3.5kB string of JSON can be compressed down ~2.5kB ([see it on Godbolt](https://godbolt.org/z/1MzG1v)).
**2. Scripts (e.g. Lisp)**
**2. Scripts (e.g. Lisp)**
A ~40 line commented sample of Lisp can be reduced from 1,662 bytes to 1,244 (418 bytes saved) ([on Godbolt](https://godbolt.org/z/c64Pzz)).
A ~40 line comment-including sample of Lisp can be reduced from 1,662 bytes to 1,244 (418 bytes saved) ([Godbolt](https://godbolt.org/z/jcnKza)).
Compression will work best on larger blocks of text or data, as a decoding tree must be stored with the compressed data that requires three bytes per unique data byte.
## How to Use
## How to Use
@ -23,15 +21,17 @@ Compression will work best on larger blocks of text or data, as a decoding tree
constexpr static const char some_data_raw[] = /* insert text here */;
constexpr static const char some_data_raw[] = /* insert text here */;
constinit static const auto some_data = consteval_huffman<some_data_raw>();
// Creates an object with the compressed data
// If data is not smaller after compression, huffman_compress will keep the data uncompressed
constinit static const auto some_data = huffman_compress<some_data_raw>();