.. getthecode:: lexical-analysis.py
    :language: python3
    :hidden:

==================
 Lexical Analysis
==================

This page contains a memo on lexical analysis.

For a complete reference documentation, look at https://docs.python.org/3.6/reference/lexical_analysis.html

Python Keywords
---------------

.. code-block:: py3

    False      class      finally    is         return
    None       continue   for        lambda     try
    True       def        from       nonlocal   while
    and        del        global     not        with
    as         elif       if         or         yield
    assert     else       import     pass
    break      except     in         raise

Reserved classes of identifiers
-------------------------------

:code:`_*`
    Not imported by from module import *
:code:`__*__`
    System-defined names
:code:`__*`
    Class-private names

Usually, :code:`_` is assigned to last evaluation or used in conjunction with *gettext* for internationalization.

Indentation
-----------
Using continuation, backslash character "\\":


.. code-block:: py3

    def check_date(year, month, day, hour, minute, second):
        if 1900 < year < 2100 and 1 <= month <= 12 \
           and 1 <= day <= 31 and 0 <= hour < 24 \
           and 0 <= minute < 60 and 0 <= second < 60:
            return True
    
Better, using parenthesis, brace and bracket:


.. code-block:: py3

    def check_date(year, month, day, hour, minute, second):
        if (1900 < year < 2100 and 1 <= month <= 12
            and 1 <= day <= 31 and 0 <= hour < 24
            and 0 <= minute < 60 and 0 <= second < 60):
            return True
    
    x = (1 +
         2 * 3 -
         4 / 6)