module Zlib
This module provides access to the zlib library. Zlib is designed to be a portable, free, general-purpose, legally unencumbered – that is, not covered by any patents – lossless data-compression library for use on virtually any computer hardware and operating system.
The zlib compression library provides in-memory compression and decompression functions, including integrity checks of the uncompressed data.
The zlib compressed data format is described in RFC 1950, which is a wrapper around a deflate stream which is described in RFC 1951.
The library also supports reading and writing files in gzip (.gz) format with an interface similar to that of IO. The gzip format is described in RFC 1952 which is also a wrapper around a deflate stream.
The zlib format was designed to be compact and fast for use in memory and on communications channels. The gzip format was designed for single-file compression on file systems, has a larger header than zlib to maintain directory information, and uses a different, slower check method than zlib.
See your system’s zlib.h for further information about zlib
Sample usage
Using the wrapper to compress strings with default parameters is quite simple:
require "zlib" data_to_compress = File.read("don_quixote.txt") puts "Input size: #{data_to_compress.size}" #=> Input size: 2347740 data_compressed = Zlib::Deflate.deflate(data_to_compress) puts "Compressed size: #{data_compressed.size}" #=> Compressed size: 887238 uncompressed_data = Zlib::Inflate.inflate(data_compressed) puts "Uncompressed data is: #{uncompressed_data}" #=> Uncompressed data is: The Project Gutenberg EBook of Don Quixote...
Class tree
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Zlib::InProgressError
(if you have GZIP_SUPPORT) * Zlib::GzipReader * Zlib::GzipWriter * Zlib::GzipFile * Zlib::GzipFile::Error * Zlib::GzipFile::LengthError * Zlib::GzipFile::CRCError * Zlib::GzipFile::NoFooter
Public Class Methods
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 88
def self.adler32: () -> Integer
| (String) -> Integer
| (String, Integer) -> Integer
Calculates Adler-32 checksum for string, and returns updated value of adler. If string is omitted, it returns the Adler-32 initial value. If adler is omitted, it assumes that the initial value is given to adler. If string is an IO instance, reads from the IO until the IO returns nil and returns Adler-32 of all read data.
Example usage:
require "zlib" data = "foo" puts "Adler32 checksum: #{Zlib.adler32(data).to_s(16)}" #=> Adler32 checksum: 2820145
Source
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 100
def self.adler32_combine: (Integer, Integer, Integer) -> Integer
Combine two Adler-32 check values in to one. adler1 is the first Adler-32 value, adler2 is the second Adler-32 value. len2 is the length of the string used to generate adler2.
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 114
def self.crc32: () -> Integer
| (String) -> Integer
| (String, Integer) -> Integer
Calculates CRC checksum for string, and returns updated value of crc. If string is omitted, it returns the CRC initial value. If crc is omitted, it assumes that the initial value is given to crc. If string is an IO instance, reads from the IO until the IO returns nil and returns CRC checksum of all read data.
FIXME: expression.
Source
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 126
def self.crc32_combine: (Integer, Integer, Integer) -> Integer
Combine two CRC-32 check values in to one. crc1 is the first CRC-32 value, crc2 is the second CRC-32 value. len2 is the length of the string used to generate crc2.
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 134
def self.crc_table: () -> Array[Integer]
Returns the table for calculating CRC checksum as an array.
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 156
def self.deflate: (String) -> String
| (String, Integer) -> String
Compresses the given string. Valid values of level are Zlib::NO_COMPRESSION, Zlib::BEST_SPEED, Zlib::BEST_COMPRESSION, Zlib::DEFAULT_COMPRESSION, or an integer from 0 to 9.
This method is almost equivalent to the following code:
def deflate(string, level) z = Zlib::Deflate.new(level) dst = z.deflate(string, Zlib::FINISH) z.close dst end
See also Zlib.inflate
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 177
def self.gunzip: (String) -> String
Decode the given gzipped string.
This method is almost equivalent to the following code:
def gunzip(string) sio = StringIO.new(string) gz = Zlib::GzipReader.new(sio, encoding: Encoding::ASCII_8BIT) gz.read ensure gz&.close end
See also Zlib.gzip
(String) → String
(String, level: Integer) → String
(String, strategy: Integer) → String
(String, level: Integer, strategy: Integer) → StringSource
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 200
def self.gzip: (String) -> String
| (String, level: Integer) -> String
| (String, strategy: Integer) -> String
| (String, level: Integer, strategy: Integer) -> String
Gzip the given string. Valid values of level are Zlib::NO_COMPRESSION, Zlib::BEST_SPEED, Zlib::BEST_COMPRESSION, Zlib::DEFAULT_COMPRESSION (default), or an integer from 0 to 9.
This method is almost equivalent to the following code:
def gzip(string, level: nil, strategy: nil) sio = StringIO.new sio.binmode gz = Zlib::GzipWriter.new(sio, level, strategy) gz.write(string) gz.close sio.string end
See also Zlib.gunzip
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 225
def self.inflate: (String) -> String
Decompresses string. Raises a Zlib::NeedDict exception if a preset dictionary is needed for decompression.
This method is almost equivalent to the following code:
def inflate(string) zstream = Zlib::Inflate.new buf = zstream.inflate(string) zstream.finish zstream.close buf end
See also Zlib.deflate
() → StringSource
# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/stdlib/zlib/0/zlib.rbs, line 233
def self.zlib_version: () -> String
Returns the string which represents the version of zlib library.