class Compress::Gzip::Writer

Overview

A write-only IO object to compress data in the gzip format.

Instances of this class wrap another IO object. When you write to this instance, it compresses the data and writes it to the underlying IO.

NOTE unless created with a block, #close must be invoked after all data has been written to a Gzip::Writer instance.

Example: compress a file

require "compress/gzip"

File.write("file.txt", "abc")

File.open("./file.txt", "r") do |input_file|
  File.open("./file.gzip", "w") do |output_file|
    Compress::Gzip::Writer.open(output_file) do |gzip|
      IO.copy(input_file, gzip)
    end
  end
end

Defined in:

compress/gzip/writer.cr

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from class IO

<<(obj) : self <<, close close, closed? : Bool closed?, each_byte(&) : Nil
each_byte
each_byte
, each_char(&) : Nil
each_char
each_char
, each_line(*args, **options, &block : String -> ) : Nil
each_line(*args, **options)
each_line
, encoding : String encoding, flush flush, getb_to_end : Bytes getb_to_end, gets(limit : Int, chomp = false) : String | Nil
gets(delimiter : Char, limit : Int, chomp = false) : String | Nil
gets(delimiter : Char, chomp = false) : String | Nil
gets(delimiter : String, chomp = false) : String | Nil
gets(chomp = true) : String | Nil
gets
, gets_to_end : String gets_to_end, peek : Bytes | Nil peek, pos pos, pos=(value) pos=, print(obj : _) : Nil
print(*objects : _) : Nil
print
, printf(format_string, args : Array | Tuple) : Nil
printf(format_string, *args) : Nil
printf
, puts(string : String) : Nil
puts(obj : _) : Nil
puts : Nil
puts(*objects : _) : Nil
puts
, read(slice : Bytes) read, read_at(offset, bytesize, & : IO -> ) read_at, read_byte : UInt8 | Nil read_byte, read_bytes(type, format : IO::ByteFormat = IO::ByteFormat::SystemEndian) read_bytes, read_char : Char | Nil read_char, read_fully(slice : Bytes) : Int32 read_fully, read_fully?(slice : Bytes) : Int32 | Nil read_fully?, read_line(*args, **options) : String read_line, read_string(bytesize : Int) : String read_string, read_utf8(slice : Bytes) read_utf8, read_utf8_byte : UInt8 | Nil read_utf8_byte, rewind rewind, seek(offset, whence : Seek = Seek::Set) seek, set_encoding(encoding : String, invalid : Symbol | Nil = nil) : Nil set_encoding, skip(bytes_count : Int) : Nil skip, skip_to_end : Nil skip_to_end, tell tell, tty? : Bool tty?, write(slice : Bytes) : Nil write, write_byte(byte : UInt8) : Nil write_byte, write_bytes(object, format : IO::ByteFormat = IO::ByteFormat::SystemEndian) : Nil write_bytes, write_string(slice : Bytes) : Nil write_string, write_utf8(slice : Bytes) : Nil write_utf8

Class methods inherited from class IO

copy(src, dst, limit : Int) : Int64
copy(src, dst) : Int64
copy
, pipe(read_blocking = false, write_blocking = false) : Tuple(IO::FileDescriptor, IO::FileDescriptor)
pipe(read_blocking = false, write_blocking = false, &)
pipe
, same_content?(stream1 : IO, stream2 : IO) : Bool same_content?

Instance methods inherited from class Reference

==(other : self)
==(other : JSON::Any)
==(other : YAML::Any)
==(other)
==
, dup dup, hash(hasher) hash, initialize initialize, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference) : Bool
same?(other : Nil)
same?
, to_s(io : IO) : Nil to_s

Constructor methods inherited from class Reference

new new

Instance methods inherited from class Object

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other)
===
, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash
hash
, in?(collection : Object) : Bool
in?(*values : Object) : Bool
in?
, inspect(io : IO) : Nil
inspect : String
inspect
, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil!
not_nil!
, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String
to_json
, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil
to_pretty_json
, to_s(io : IO) : Nil
to_s : String
to_s
, to_yaml(io : IO) : Nil
to_yaml : String
to_yaml
, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

Class methods inherited from class Object

from_json(string_or_io, root : String)
from_json(string_or_io)
from_json
, from_yaml(string_or_io : String | IO) from_yaml

Constructor Detail

def self.new(io : IO, level : Int32 = Compress::Gzip::DEFAULT_COMPRESSION, sync_close : Bool = false) #

Creates a new writer to the given io.


[View source]
def self.new(filename : String, level = Compress::Gzip::DEFAULT_COMPRESSION) #

Creates a new writer to the given filename.


[View source]

Class Method Detail

def self.open(io : IO, level = Compress::Gzip::DEFAULT_COMPRESSION, sync_close = false, &) #

Creates a new writer to the given io, yields it to the given block, and closes it at the end.


[View source]
def self.open(filename : String, level = Compress::Gzip::DEFAULT_COMPRESSION, &) #

Creates a new writer to the given filename, yields it to the given block, and closes it at the end.


[View source]

Instance Method Detail

def close : Nil #

Closes this writer. Must be invoked after all data has been written.


[View source]
def closed? : Bool #

Returns true if this writer is closed.


[View source]
def flush : Nil #

Flushes data, forcing writing the gzip header if no data has been written yet.

See IO#flush.


[View source]
def header : Compress::Gzip::Header #

The header to write to the gzip stream. It will be written just before the first write to this writer. Changes to the header after the first write are ignored.


[View source]
def read(slice : Bytes) : NoReturn #

Always raises IO::Error because this is a write-only IO.


[View source]
def sync_close=(sync_close : Bool) #

Whether to close the enclosed IO when closing this writer.


[View source]
def sync_close? : Bool #

Whether to close the enclosed IO when closing this writer.


[View source]
def write(slice : Bytes) : Nil #

See IO#write.


[View source]