consteval-huffman

Allows for long string or data constants to be compressed at compile-time, with a small decoder routine for decompression at run-time.

Compression is achieved using Huffman coding, which works by creating codes for frequently-occuring characters.

Use cases

1. Text configurations (e.g. JSON)

A ~3.5kB string of JSON can be compressed down ~2.5kB (see it on Godbolt).

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).

Compression will work best on not-small blocks of text or data. This is because a decoding tree must be stored with the compressed data, requiring three bytes per value.

How to Use

#include "consteval_huffman.hpp"

constexpr static const char some_data_raw[] = /* insert text here */;

constinit static const auto some_data = consteval_huffman<some_data_raw>();

// Or, with a set data length:
// ... some_data = consteval_huffman<some_data_raw, 1500>();

int main()
{
    // Decompress and print out the data
    for (auto decode = some_data.get_decoder(); decode; ++decode)
        putchar(*decode);
}