lz4.Decompressor

The Decompressor struct maintains a persistent configuration, memory allocator, and optional dictionary. It automatically handles both LZ4 Frames and Raw Blocks.

pub const Decompressor = struct {
    allocator: std.mem.Allocator,
    options: DecompressionOptions,
    dict: ?[]const u8 = null,
    // ...
};

---

Methods

init

pub fn init(allocator: std.mem.Allocator, opts: DecompressionOptions) Decompressor

Initializes a new Decompressor instance with the specified allocator and decompression options.

Parameters

• allocator: Memory allocator used for allocated decompression outputs.
• opts: Configuration options controlling maximum uncompressed size, dictionary, etc.

---

deinit

pub fn deinit(self: *Decompressor) void

Releases any internal resources owned by the decompressor.

---

reset

pub fn reset(self: *Decompressor, opts: DecompressionOptions) void

Resets options and dictionary configuration without re-allocating the struct.

---

attachDictionary

pub fn attachDictionary(self: *Decompressor, dict: []const u8) void

Attaches an in-memory dictionary slice for subsequent decompression operations.

---

decompress

pub fn decompress(self: *Decompressor, src: []const u8) ![]u8

Decompresses src into a newly allocated slice. Automatically handles standard LZ4 frames or raw blocks. The caller owns the returned slice and must free it with self.allocator.

Errors

• error.OutOfMemory: Failed to allocate uncompressed output buffer.
• error.MalformedInput: Invalid LZ4 sequence or corrupted tokens.
• error.BadChecksum: Checksum verification mismatch.
• error.OutputTooLarge: Decompressed content exceeded maxOutputSize.

---

decompressInto

pub fn decompressInto(self: *Decompressor, src: []const u8, dst: []u8) !usize

Decompresses src directly into the caller-provided dst buffer. Returns the exact number of decompressed bytes written.

Errors

• error.DestinationBufferTooSmall: Caller buffer is too small to contain the uncompressed data.
• error.MalformedInput: Corrupt byte stream.

---

Example Usage

const std = @import("std");
const lz4 = @import("lz4");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    var decompressor = lz4.Decompressor.init(allocator, .{
        .maxOutputSize = 50 * 1024 * 1024, // 50 MiB safety cap
    });
    defer decompressor.deinit();

    const restored = try decompressor.decompress(compressed_data);
    defer allocator.free(restored);

    std.debug.print("Restored {d} bytes\n", .{restored.len});
}