Doc/lib/libtokenize.tex

   1 \section{\module{tokenize} ---
   2          Tokenizer for Python source}
   3
   4 \declaremodule{standard}{tokenize}
   5 \modulesynopsis{Lexical scanner for Python source code.}
   6 \moduleauthor{Ka Ping Yee}{}
   7 \sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
   8
   9
  10 The \module{tokenize} module provides a lexical scanner for Python
  11 source code, implemented in Python.  The scanner in this module
  12 returns comments as tokens as well, making it useful for implementing
  13 ``pretty-printers,'' including colorizers for on-screen displays.
  14
  15 The primary entry point is a generator:
  16
  17 \begin{funcdesc}{generate_tokens}{readline}
  18   The \function{generate_tokens()} generator requires one argment,
  19   \var{readline}, which must be a callable object which
  20   provides the same interface as the \method{readline()} method of
  21   built-in file objects (see section~\ref{bltin-file-objects}).  Each
  22   call to the function should return one line of input as a string.
  23
  24   The generator produces 5-tuples with these members:
  25   the token type;
  26   the token string;
  27   a 2-tuple \code{(\var{srow}, \var{scol})} of ints specifying the
  28   row and column where the token begins in the source;
  29   a 2-tuple \code{(\var{erow}, \var{ecol})} of ints specifying the
  30   row and column where the token ends in the source;
  31   and the line on which the token was found.
  32   The line passed is the \emph{logical} line;
  33   continuation lines are included.
  34   \versionadded{2.2}
  35 \end{funcdesc}
  36
  37 An older entry point is retained for backward compatibility:
  38
  39 \begin{funcdesc}{tokenize}{readline\optional{, tokeneater}}
  40   The \function{tokenize()} function accepts two parameters: one
  41   representing the input stream, and one providing an output mechanism
  42   for \function{tokenize()}.
  43
  44   The first parameter, \var{readline}, must be a callable object which
  45   provides the same interface as the \method{readline()} method of
  46   built-in file objects (see section~\ref{bltin-file-objects}).  Each
  47   call to the function should return one line of input as a string.
  48
  49   The second parameter, \var{tokeneater}, must also be a callable
  50   object.  It is called once for each token, with five arguments,
  51   corresponding to the tuples generated by \function{generate_tokens()}.
  52 \end{funcdesc}
  53
  54
  55 All constants from the \refmodule{token} module are also exported from
  56 \module{tokenize}, as are two additional token type values that might be
  57 passed to the \var{tokeneater} function by \function{tokenize()}:
  58
  59 \begin{datadesc}{COMMENT}
  60   Token value used to indicate a comment.
  61 \end{datadesc}
  62 \begin{datadesc}{NL}
  63   Token value used to indicate a non-terminating newline.  The NEWLINE
  64   token indicates the end of a logical line of Python code; NL tokens
  65   are generated when a logical line of code is continued over multiple
  66   physical lines.
  67 \end{datadesc}