diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/tokenize.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/tokenize.rst Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,121 @@ + +:mod:`tokenize` --- Tokenizer for Python source +=============================================== + +.. module:: tokenize + :synopsis: Lexical scanner for Python source code. +.. moduleauthor:: Ka Ping Yee +.. sectionauthor:: Fred L. Drake, Jr. + + +The :mod:`tokenize` module provides a lexical scanner for Python source code, +implemented in Python. The scanner in this module returns comments as tokens as +well, making it useful for implementing "pretty-printers," including colorizers +for on-screen displays. + +The primary entry point is a :term:`generator`: + +.. function:: generate_tokens(readline) + + The :func:`generate_tokens` generator requires one argument, *readline*, + which must be a callable object which provides the same interface as the + :meth:`readline` method of built-in file objects (see section + :ref:`bltin-file-objects`). Each call to the function should return one line + of input as a string. + + The generator produces 5-tuples with these members: the token type; the token + string; a 2-tuple ``(srow, scol)`` of ints specifying the row and column + where the token begins in the source; a 2-tuple ``(erow, ecol)`` of ints + specifying the row and column where the token ends in the source; and the + line on which the token was found. The line passed (the last tuple item) is + the *logical* line; continuation lines are included. + + .. versionadded:: 2.2 + +An older entry point is retained for backward compatibility: + + +.. function:: tokenize(readline[, tokeneater]) + + The :func:`tokenize` function accepts two parameters: one representing the input + stream, and one providing an output mechanism for :func:`tokenize`. + + The first parameter, *readline*, must be a callable object which provides the + same interface as the :meth:`readline` method of built-in file objects (see + section :ref:`bltin-file-objects`). Each call to the function should return one + line of input as a string. Alternately, *readline* may be a callable object that + signals completion by raising :exc:`StopIteration`. + + .. versionchanged:: 2.5 + Added :exc:`StopIteration` support. + + The second parameter, *tokeneater*, must also be a callable object. It is + called once for each token, with five arguments, corresponding to the tuples + generated by :func:`generate_tokens`. + +All constants from the :mod:`token` module are also exported from +:mod:`tokenize`, as are two additional token type values that might be passed to +the *tokeneater* function by :func:`tokenize`: + + +.. data:: COMMENT + + Token value used to indicate a comment. + + +.. data:: NL + + Token value used to indicate a non-terminating newline. The NEWLINE token + indicates the end of a logical line of Python code; NL tokens are generated when + a logical line of code is continued over multiple physical lines. + +Another function is provided to reverse the tokenization process. This is useful +for creating tools that tokenize a script, modify the token stream, and write +back the modified script. + + +.. function:: untokenize(iterable) + + Converts tokens back into Python source code. The *iterable* must return + sequences with at least two elements, the token type and the token string. Any + additional sequence elements are ignored. + + The reconstructed script is returned as a single string. The result is + guaranteed to tokenize back to match the input so that the conversion is + lossless and round-trips are assured. The guarantee applies only to the token + type and token string as the spacing between tokens (column positions) may + change. + + .. versionadded:: 2.5 + +Example of a script re-writer that transforms float literals into Decimal +objects:: + + def decistmt(s): + """Substitute Decimals for floats in a string of statements. + + >>> from decimal import Decimal + >>> s = 'print +21.3e-5*-.1234/81.7' + >>> decistmt(s) + "print +Decimal ('21.3e-5')*-Decimal ('.1234')/Decimal ('81.7')" + + >>> exec(s) + -3.21716034272e-007 + >>> exec(decistmt(s)) + -3.217160342717258261933904529E-7 + + """ + result = [] + g = generate_tokens(StringIO(s).readline) # tokenize the string + for toknum, tokval, _, _, _ in g: + if toknum == NUMBER and '.' in tokval: # replace NUMBER tokens + result.extend([ + (NAME, 'Decimal'), + (OP, '('), + (STRING, repr(tokval)), + (OP, ')') + ]) + else: + result.append((toknum, tokval)) + return untokenize(result) +