boost::capy::zlib::deflate_service

Provides the ZLib compression API.

Synopsis

Declared in <boost/capy/zlib/deflate.hpp>

struct deflate_service;

Description

This service interface exposes the ZLib deflate (compression) functionality through a set of virtual functions. The deflate algorithm compresses data by finding repeated byte sequences and encoding them efficiently using a combination of LZ77 and Huffman coding.

The windowBits parameter in init2() controls the format: ‐ 8..15: zlib format with specified window size ‐ ‐8..‐15: raw deflate format (no header/trailer) ‐ 16+windowBits: gzip format

// Example: Basic compression
boost::capy::datastore ctx;
auto& deflate_svc = boost::capy::zlib::install_deflate_service(ctx);

boost::capy::zlib::stream st = {};
std::vector<unsigned char> input_data = get_data();
std::vector<unsigned char> output(input_data.size() * 2);

st.zalloc = nullptr;
st.zfree = nullptr;
st.opaque = nullptr;

deflate_svc.init(st, boost::capy::zlib::default_compression);

st.avail_in = input_data.size();
st.next_in = input_data.data();
st.avail_out = output.size();
st.next_out = output.data();

deflate_svc.deflate(st, boost::capy::zlib::finish);
output.resize(st.total_out);

deflate_svc.deflate_end(st);
// Example: Gzip compression with custom window size
boost::capy::zlib::stream st = {};
st.zalloc = nullptr;
st.zfree = nullptr;

// Use gzip format (16 + 15 for max window)
deflate_svc.init2(st,
    6,                                      // level
    boost::capy::zlib::deflated,           // method
    16 + 15,                                // gzip format
    8,                                      // memLevel
    boost::capy::zlib::default_strategy);   // strategy

// Compress data...
deflate_svc.deflate_end(st);

Member Functions

Name

Description

bound [virtual]

Return an upper bound on compressed size.

deflate [virtual]

Compress data in the stream.

deflate_end [virtual]

Release all resources held by the deflate stream.

dup [virtual]

Duplicate a deflate stream.

get_dict [virtual]

Return the current compression dictionary.

init [virtual]

Initialize deflate compression.

init2 [virtual]

Initialize deflate compression with extended parameters.

params [virtual]

Dynamically update compression parameters.

pending [virtual]

Return the number of pending output bytes.

prime [virtual]

Insert bits into the compressed stream.

reset [virtual]

Reset the deflate stream state.

set_dict [virtual]

Set the compression dictionary.

set_header [virtual]

Set the gzip header information.

version [virtual]

Return the ZLib version string.

Non-Member Functions

Name

Description

install_deflate_service

Install the deflate service into a polystore.

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