This content originally appeared on DEV Community and was authored by Sam
LuaRT provides a builtin zip module to work with compressed files in ZIP format, without any additional dependencies.
ZIP archive files
ZIP is a file format that supports lossless compression. A lossless compression algorithm allows the original data to be perfectly reconstructed from the compressed data. A ZIP file contains one or more compressed files, making it an ideal way to reduce the size of large files and keep related files together.
The Zip Object
The LuaRT 'zip' module provides an abstraction of zip files represented as a Zip Object. Only INFLATE/DEFLATE algorithms are supported.
This module facilitates the creation of ZIP archive files and provides methods and properties for adding and extracting compressed files.
To use the Zip Object, you must first require for the 'zip' module :
-- require the builtin 'zip' module for the Zip object
local Zip = require "zip"
Extract files from a ZIP archive
To extract files from an existing ZIP archive, you can use the Zip:extractall() method :
local Zip = require "zip"
-- Create a Zip value to represent the ZIP file 'archive.zip'
local archive = Zip("archive.zip")
-- open the ZIP archive for reading
archive:open("read")
-- extract and uncompress all the files in the current directory
archive:extractall()
You can extract a specific entry with the Zip:extract() method :
-- extract the ZIP entry "extractme.bin" in the current directory
archive:extract("extractme.bin")
A destination path can optionaly be provided :
-- extract the ZIP entry "data.bin" in the specified directory
archive:extract("data.bin", "C:\\Extract\\Me\\Here")
Creating a ZIP archive
Zip:open() can be used to create an empty ZIP archive. Files can be added to the archive with the Zip:write() method:
local Zip = require "zip"
-- Create a Zip value to represent the ZIP file 'new.zip'
local archive = Zip("new.zip")
-- open the ZIP archive for writing
archive:open("write")
-- add a file to this archive
archive:write("C:\\addme.txt"))
You can recursively add entire directories too :
archive:write("C:\\I_am_a_directory_addme\\"))
Iterating over files in a ZIP archive
Zip object is iterable with the each() function, returning at every iteration the next entry name in the ZIP archive previously opened in "read" mode:
local Zip = require "zip"
-- Create a Zip value to represent the ZIP file 'archive.zip'
local archive = Zip("archive.zip")
-- open the ZIP archive for reading
archive:open("read")
-- Iterate over each ZIP archive entries and extract it
for entry in each(archive) do
print("Extracting '"..entry.."'")
archive:extract(entry)
end
Reading ZIP archive entries in memory
ZIP archive entries can also be extracted in-memory using the Zip:read() method :
local Zip = require "zip"
-- Create a Zip value to represent the ZIP file 'archive.zip'
local archive = Zip("archive.zip")
-- open the ZIP archive for reading
archive:open("read")
-- print the content of the ZIP archive entry 'README.TXT'
print(archive:read("README.TXT")
As you can see, LuaRT's 'zip' module provides an easy way to manage ZIP archives. Additionally, you can read the complete Zip object specification Zip Object
This content originally appeared on DEV Community and was authored by Sam
Sam | Sciencx (2021-09-28T17:09:06+00:00) Working with ZIP files in LuaRT. Retrieved from https://www.scien.cx/2021/09/28/working-with-zip-files-in-luart/
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