# 11.12 `urlparse` -- Parse URLs into components

This module defines a standard interface to break Uniform Resource Locator (URL) strings up in components (addressing scheme, network location, path etc.), to combine the components back into a URL string, and to convert a ``relative URL'' to an absolute URL given a ``base URL.''

The module has been designed to match the Internet RFC on Relative Uniform Resource Locators (and discovered a bug in an earlier draft!).

It defines the following functions:

`urlparse` (urlstring[, default_scheme[, allow_fragments]])
  Parse a URL into 6 components, returning a 6-tuple: (addressing scheme, network location, path, parameters, query, fragment identifier). This corresponds to the general structure of a URL: `scheme://netloc/path;parameters?query#fragment`. Each tuple item is a string, possibly empty. The components are not broken up in smaller parts (e.g. the network location is a single string), and % escapes are not expanded. The delimiters as shown above are not part of the tuple items, except for a leading slash in the path component, which is retained if present.

  Example:

        urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')

  yields the tuple

        ('http', 'www.cwi.nl:80', '/%7Eguido/Python.html', '', '', '')

  If the default_scheme argument is specified, it gives the default addressing scheme, to be used only if the URL string does not specify one. The default value for this argument is the empty string.

  If the allow_fragments argument is zero, fragment identifiers are not allowed, even if the URL's addressing scheme normally does support them. The default value for this argument is `1`.

`urlunparse` (tuple)
  Construct a URL string from a tuple as returned by `urlparse()`. This may result in a slightly different, but equivalent URL, if the URL that was parsed originally had redundant delimiters, e.g. a ? with an empty query (the draft states that these are equivalent).

`urljoin` (base, url[, allow_fragments])
  Construct a full (``absolute'') URL by combining a ``base URL'' (base) with a ``relative URL'' (url). Informally, this uses components of the base URL, in particular the addressing scheme, the network location and (part of) the path, to provide missing components in the relative URL.

  Example:

        urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')

  yields the string

        'http://www.cwi.nl/%7Eguido/FAQ.html'

  The allow_fragments argument has the same meaning as for `urlparse()`.

See Also:

RFC 1738, Uniform Resource Locators (URL)
  This specifies the formal syntax and semantics of absolute URLs.

RFC 1808, Relative Uniform Resource Locators
  This Request For Comments includes the rules for joining an absolute and a relative URL, including a fair normal of ``Abnormal Examples'' which govern the treatment of border cases.

RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax
  Document describing the generic syntactic requirements for both Uniform Resource Names (URNs) and Uniform Resource Locators (URLs).