A Robust URL Parser and Builder for Lua

This small Lua library provides a few functions to parse URL with querystring and build new URL easily.

> url = require "net.url"

Querystring parser

The library supports brackets in querystrings, like PHP. It means you can use brackets to build multi-dimensional tables. The parsed querystring has a tostring() helper. As usual with Lua, if no index is specified, it starts from index 1.

> query = url.parseQuery("first=abc&a[]=123&a[]=false&b[]=str&c[]=3.5&a[]=last")
> = query
a[1]=123&a[2]=false&a[3]=last&b[1]=str&c[1]=3.5&first=abc
> = query.a[1]
123

URL parser

The library converts an URL to a table of the elements as described in RFC : scheme, host, path, etc.

> u = url.parse("http://www.example.com/test/?start=10")
> = u.scheme
http
> = u.host
www.example.com
> = u.path
/test/

URL normalization

> = url.parse("http://www.FOO.com:80///foo/../foo/./bar"):normalize()
http://www.foo.com/foo/bar

URL resolver

URL resolution follows the examples provided in the RFC 2396.

> = url.parse("http://a/b/c/d;p?q"):resolve("../../g")
http://a/g

Querystring builder

> u = url.parse("http://www.example.com")
> u.query.foo = "bar"
> = u
http://www.example.com/?foo=bar

> u:setQuery{ json = true, skip = 100 }
http://www.example.com/?json=true&skip=100

Differences with luasocket/url.lua

• Luasocket/url.lua can't parse http://www.example.com?url=net correctly because there are no path.
• Luasocket/url.lua can't clean and normalize url, for example by removing default port, extra zero in port, empty authority, uppercase scheme, domain name.
• Luasocket/url.lua doesn't parse the query string parameters.
• Luasocket/url.lua is less compliant with RFC 2396 and will resolve http://a/b/c/d;p?q and : ../../../g to http://ag instead of http://a/g ../../../../g to http://a../g instead of http://a/g g;x=1/../y to http://a/b/c/g;x=1/../y instead of http://a/b/c/y /./g to http://a/./g instead of http://a/g g;x=1/./y to http://a/b/c/g;x=1/./y instead of http://a/b/c/g;x=1/y