Doc/lib/liburlparse.tex

   1 \section{\module{urlparse} ---
   2          Parse URLs into components}
   3 \declaremodule{standard}{urlparse}
   4
   5 \modulesynopsis{Parse URLs into components.}
   6
   7 \index{WWW}
   8 \index{World-Wide Web}
   9 \index{URL}
  10 \indexii{URL}{parsing}
  11 \indexii{relative}{URL}
  12
  13
  14 This module defines a standard interface to break Uniform Resource
  15 Locator (URL) strings up in components (addressing scheme, network
  16 location, path etc.), to combine the components back into a URL
  17 string, and to convert a ``relative URL'' to an absolute URL given a
  18 ``base URL.''
  19
  20 The module has been designed to match the Internet RFC on Relative
  21 Uniform Resource Locators (and discovered a bug in an earlier
  22 draft!).
  23
  24 It defines the following functions:
  25
  26 \begin{funcdesc}{urlparse}{urlstring\optional{, default_scheme\optional{, allow_fragments}}}
  27 Parse a URL into 6 components, returning a 6-tuple: (addressing
  28 scheme, network location, path, parameters, query, fragment
  29 identifier).  This corresponds to the general structure of a URL:
  30 \code{\var{scheme}://\var{netloc}/\var{path};\var{parameters}?\var{query}\#\var{fragment}}.
  31 Each tuple item is a string, possibly empty.
  32 The components are not broken up in smaller parts (e.g. the network
  33 location is a single string), and \% escapes are not expanded.
  34 The delimiters as shown above are not part of the tuple items,
  35 except for a leading slash in the \var{path} component, which is
  36 retained if present.
  37
  38 Example:
  39
  40 \begin{verbatim}
  41 urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
  42 \end{verbatim}
  43
  44 yields the tuple
  45
  46 \begin{verbatim}
  47 ('http', 'www.cwi.nl:80', '/%7Eguido/Python.html', '', '', '')
  48 \end{verbatim}
  49
  50 If the \var{default_scheme} argument is specified, it gives the
  51 default addressing scheme, to be used only if the URL string does not
  52 specify one.  The default value for this argument is the empty string.
  53
  54 If the \var{allow_fragments} argument is zero, fragment identifiers
  55 are not allowed, even if the URL's addressing scheme normally does
  56 support them.  The default value for this argument is \code{1}.
  57 \end{funcdesc}
  58
  59 \begin{funcdesc}{urlunparse}{tuple}
  60 Construct a URL string from a tuple as returned by \code{urlparse()}.
  61 This may result in a slightly different, but equivalent URL, if the
  62 URL that was parsed originally had redundant delimiters, e.g. a ? with
  63 an empty query (the draft states that these are equivalent).
  64 \end{funcdesc}
  65
  66 \begin{funcdesc}{urljoin}{base, url\optional{, allow_fragments}}
  67 Construct a full (``absolute'') URL by combining a ``base URL''
  68 (\var{base}) with a ``relative URL'' (\var{url}).  Informally, this
  69 uses components of the base URL, in particular the addressing scheme,
  70 the network location and (part of) the path, to provide missing
  71 components in the relative URL.
  72
  73 Example:
  74
  75 \begin{verbatim}
  76 urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')
  77 \end{verbatim}
  78
  79 yields the string
  80
  81 \begin{verbatim}
  82 'http://www.cwi.nl/%7Eguido/FAQ.html'
  83 \end{verbatim}
  84
  85 The \var{allow_fragments} argument has the same meaning as for
  86 \code{urlparse()}.
  87 \end{funcdesc}
  88
  89
  90 \begin{seealso}
  91   \seerfc{1738}{Uniform Resource Locators (URL)}{
  92         This specifies the formal syntax and semantics of absolute
  93         URLs.}
  94   \seerfc{1808}{Relative Uniform Resource Locators}{
  95         This Request For Comments includes the rules for joining an
  96         absolute and a relative URL, including a fair normal of
  97         ``Abnormal Examples'' which govern the treatment of border
  98         cases.}
  99   \seerfc{2396}{Uniform Resource Identifiers (URI): Generic Syntax}{
 100         Document describing the generic syntactic requirements for
 101         both Uniform Resource Names (URNs) and Uniform Resource
 102         Locators (URLs).}
 103 \end{seealso}