Zlib bindings

The zlib module provides single-call and stream-oriented functions for interacting with zlib data.

Source: lib/zlib.c, line 17

Classes

zlib.zstrmd

Represents a handle for interacting with a deflate stream initiated by defnew().

zlib.zstrmi

Represents a handle for interacting with an inflate stream initiated by infnew().

Methods

deflate(str_or_resource, gzipopt, nullable, levelopt, nullable) → {string}nullable

Compresses data in Zlib or gzip format.

If the input argument is a plain string, it is directly compressed.

If an array, object or resource value is given, this function will attempt to invoke a read() method on it to read chunks of input text to incrementally compress. Reading will stop if the object's read() method returns either null or an empty string.

Throws an exception on errors.

Returns the compressed data.

Parameters:

Name	Type	Description
`str_or_resource`	string	The string or resource object to be compressed.
`gzip`	boolean	(optional, nullable, default: `false`) Add a gzip header if true (creates a gzip-compliant output, otherwise defaults to Zlib)
`level`	number	(optional, nullable, default: `Z_DEFAULT_COMPRESSION`) The compression level (0-9).

Returns: string

Example

// deflate content using default compression
const deflated = deflate(content);

// deflate content using fastest compression
const deflated = deflate(content, Z_BEST_SPEED);

Source: lib/zlib.c, line 169

defnew(gzipopt, nullable, levelopt, nullable) → {zstrmd}nullable

Initializes a deflate stream.

Returns a stream handle on success.

Returns null if an error occurred.

Parameters:

Name	Type	Description
`gzip`	boolean	(optional, nullable, default: `false`) Add a gzip header if true (creates a gzip-compliant output, otherwise defaults to Zlib)
`level`	number	(optional, nullable, default: `Z_DEFAULT_COMPRESSION`) The compression level (0-9).

Returns: zstrmd

Example

// initialize a Zlib deflate stream using default compression
const zstrmd = defnew();

// initialize a gzip deflate stream using fastest compression
const zstrmd = defnew(true, Z_BEST_SPEED);

Source: lib/zlib.c, line 494

inflate(str_or_resource) → {string}nullable

Decompresses data in Zlib or gzip format.

If the input argument is a plain string, it is directly decompressed.

If an array, object or resource value is given, this function will attempt to invoke a read() method on it to read chunks of input text to incrementally decompress. Reading will stop if the object's read() method returns either null or an empty string.

Throws an exception on errors.

Returns the decompressed data.

Parameters:

Name	Type	Description
`str_or_resource`	string	The string or resource object to be parsed as JSON.

Returns: string

Source: lib/zlib.c, line 388

infnew() → {zstrmi}nullable

Initializes an inflate stream. Can process either Zlib or gzip data.

Returns a stream handle on success.

Returns null if an error occurred.

Returns: zstrmi

Example

// initialize an inflate stream
const zstrmi = infnew();

Source: lib/zlib.c, line 700

Type Definitions

Compression levels

Constants representing predefined compression levels.

Properties

Name	Type	Description
`Z_NO_COMPRESSION.`	number
`Z_BEST_SPEED.`	number
`Z_BEST_COMPRESSION.`	number
`Z_DEFAULT_COMPRESSION`	number	default compromise between speed and compression (currently equivalent to level 6).

Source: lib/zlib.c, line 923

flush options

Constants representing flush options.

Properties

Name	Type	Description
`Z_NO_FLUSH.`	number
`Z_PARTIAL_FLUSH.`	number
`Z_SYNC_FLUSH.`	number
`Z_FULL_FLUSH.`	number
`Z_FINISH.`	number

Source: lib/zlib.c, line 937