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# 32.7. `tokenize` — Analyseur lexical de Python

Code source : Lib/tokenize.py

Le module `tokenize` fournit un analyseur lexical pour Python, implémenté en Python. L’analyseur de ce module renvoie les commentaire sous forme de token, se qui le rend intéressant pour implémenter des pretty-printers, typiquement pour faire de la coloration syntaxique.

To simplify token stream handling, all Opérateurs and Délimiteurs tokens are returned using the generic `token.OP` token type. The exact type can be determined by checking the second field (containing the actual token string matched) of the tuple returned from `tokenize.generate_tokens()` for the character sequence that identifies a specific operator token.

Le point d’entrée principal est un générateur :

`tokenize.``generate_tokens`(readline)

  The `generate_tokens()` generator requires one argument, readline, which must be a callable object which provides the same interface as the `readline()` method of built-in file objects (see section Objets fichiers). 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 `StopIteration`.

  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.

  Nouveau dans la version 2.2.

An older entry point is retained for backward compatibility:

`tokenize.``tokenize`(readline[, tokeneater])

  The `tokenize()` function accepts two parameters: one representing the input stream, and one providing an output mechanism for `tokenize()`.

  The first parameter, readline, must be a callable object which provides the same interface as the `readline()` method of built-in file objects (see section Objets fichiers). 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 `StopIteration`.

  Modifié dans la version 2.5: Added `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 `generate_tokens()`.

All constants from the `token` module are also exported from `tokenize`, as are two additional token type values that might be passed to the tokeneater function by `tokenize()`:

`tokenize.``COMMENT`

  Valeur du jeton utilisée pour indiquer un commentaire.

`tokenize.``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.

Une autre fonction est fournie pour inverser le processus de tokenisation. Ceci est utile pour créer des outils permettant de codifier un script, de modifier le flux de jetons et de réécrire le script modifié.

`tokenize.``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.

  Le script reconstruit est renvoyé sous la forme d’une chaîne unique. Le résultat est garanti pour que le jeton corresponde à l’entrée afin que la conversion soit sans perte et que les allers et retours soient assurés. La garantie ne s’applique qu’au type de jeton et à la chaîne de jetons car l’espacement entre les jetons (positions des colonnes) peut changer.

  Nouveau dans la version 2.5.

exception `tokenize.``TokenError`

  Déclenché lorsque soit une docstring soit une expression qui pourrait être divisée sur plusieurs lignes n’est pas complété dans le fichier, par exemple :

      """Beginning of
      docstring

  ou :

      [1,
       2,
       3

Note that unclosed single-quoted strings do not cause an error to be raised. They are tokenized as `ERRORTOKEN`, followed by the tokenization of their contents.

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)