.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        Click :ref:`here <sphx_glr_download_examples_advanced_python_parser.py>`     to download the full example code
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_examples_advanced_python_parser.py:


Grammar-complete Python Parser
==============================

A fully-working Python 2 & 3 parser (but not production ready yet!)

This example demonstrates usage of the included Python grammars


.. code-block:: default

    import sys
    import os, os.path
    from io import open
    import glob, time

    from lark import Lark
    from lark.indenter import Indenter

    # __path__ = os.path.dirname(__file__)

    class PythonIndenter(Indenter):
        NL_type = '_NEWLINE'
        OPEN_PAREN_types = ['LPAR', 'LSQB', 'LBRACE']
        CLOSE_PAREN_types = ['RPAR', 'RSQB', 'RBRACE']
        INDENT_type = '_INDENT'
        DEDENT_type = '_DEDENT'
        tab_len = 8

    kwargs = dict(rel_to=__file__, postlex=PythonIndenter(), start='file_input')

    python_parser2 = Lark.open('python2.lark', parser='lalr', **kwargs)
    python_parser3 = Lark.open('python3.lark',parser='lalr', **kwargs)
    python_parser2_earley = Lark.open('python2.lark', parser='earley', lexer='standard', **kwargs)

    try:
        xrange
    except NameError:
        chosen_parser = python_parser3
    else:
        chosen_parser = python_parser2


    def _read(fn, *args):
        kwargs = {'encoding': 'iso-8859-1'}
        with open(fn, *args, **kwargs) as f:
            return f.read()

    def _get_lib_path():
        if os.name == 'nt':
            if 'PyPy' in sys.version:
                return os.path.join(sys.prefix, 'lib-python', sys.winver)
            else:
                return os.path.join(sys.prefix, 'Lib')
        else:
            return [x for x in sys.path if x.endswith('%s.%s' % sys.version_info[:2])][0]

    def test_python_lib():
        path = _get_lib_path()

        start = time.time()
        files = glob.glob(path+'/*.py')
        for f in files:
            print( f )
            chosen_parser.parse(_read(os.path.join(path, f)) + '\n')

        end = time.time()
        print( "test_python_lib (%d files), time: %s secs"%(len(files), end-start) )

    def test_earley_equals_lalr():
        path = _get_lib_path()

        files = glob.glob(path+'/*.py')
        for f in files:
            print( f )
            tree1 = python_parser2.parse(_read(os.path.join(path, f)) + '\n')
            tree2 = python_parser2_earley.parse(_read(os.path.join(path, f)) + '\n')
            assert tree1 == tree2


    if __name__ == '__main__':
        test_python_lib()
        # test_earley_equals_lalr()
        # python_parser3.parse(_read(sys.argv[1]) + '\n')



.. rst-class:: sphx-glr-timing

   **Total running time of the script:** ( 0 minutes  0.000 seconds)


.. _sphx_glr_download_examples_advanced_python_parser.py:


.. only :: html

 .. container:: sphx-glr-footer
    :class: sphx-glr-footer-example



  .. container:: sphx-glr-download sphx-glr-download-python

     :download:`Download Python source code: python_parser.py <python_parser.py>`



  .. container:: sphx-glr-download sphx-glr-download-jupyter

     :download:`Download Jupyter notebook: python_parser.ipynb <python_parser.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_
