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.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "examples/advanced/dynamic_complete.py"
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.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_examples_advanced_dynamic_complete.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_examples_advanced_dynamic_complete.py:


Using lexer dynamic_complete
============================

Demonstrates how to use ``lexer='dynamic_complete'`` and ``ambiguity='explicit'``

Sometimes you have data that is highly ambiguous or 'broken' in some sense.
When using ``parser='earley'`` and ``lexer='dynamic_complete'``, Lark will be able
parse just about anything as long as there is a valid way to generate it from
the Grammar, including looking 'into' the Regexes.

This examples shows how to parse a json input where the quotes have been
replaced by underscores: ``{_foo_:{}, _bar_: [], _baz_: __}``
Notice that underscores might still appear inside strings, so a potentially
valid reading of the above is:
``{"foo_:{}, _bar": [], "baz": ""}``

.. GENERATED FROM PYTHON SOURCE LINES 18-144

.. code-block:: default

    from pprint import pprint

    from lark import Lark, Tree, Transformer, v_args
    from lark.visitors import Transformer_InPlace

    GRAMMAR = r"""
    %import common.SIGNED_NUMBER
    %import common.WS_INLINE
    %import common.NEWLINE
    %ignore WS_INLINE

    ?start: value

    ?value: object
          | array
          | string
          | SIGNED_NUMBER      -> number
          | "true"             -> true
          | "false"            -> false
          | "null"             -> null

    array  : "[" (value ("," value)*)? "]"
    object : "{" (pair ("," pair)*)? "}"
    pair   : string ":" value

    string: STRING
    STRING : ESCAPED_STRING

    ESCAPED_STRING: QUOTE_CHAR _STRING_ESC_INNER QUOTE_CHAR
    QUOTE_CHAR: "_"

    _STRING_INNER: /.*/
    _STRING_ESC_INNER: _STRING_INNER /(?<!\\)(\\\\)*?/

    """


    def score(tree: Tree):
        """
        Scores an option by how many children (and grand-children, and
        grand-grand-children, ...) it has.
        This means that the option with fewer large terminals gets selected

        Between
            object
              pair
                string	_foo_
                object
              pair
                string	_bar_: [], _baz_
                string	__

        and

            object
              pair
                string	_foo_
                object
              pair
                string	_bar_
                array
              pair
                string	_baz_
                string	__

        this will give the second a higher score. (9 vs 13)
        """
        return sum(len(t.children) for t in tree.iter_subtrees())


    class RemoveAmbiguities(Transformer_InPlace):
        """
        Selects an option to resolve an ambiguity using the score function above.
        Scores each option and selects the one with the higher score, e.g. the one
        with more nodes.

        If there is a performance problem with the Tree having to many _ambig and
        being slow and to large, this can instead be written as a ForestVisitor.
        Look at the 'Custom SPPF Prioritizer' example.
        """
        def _ambig(self, options):
            return max(options, key=score)


    class TreeToJson(Transformer):
        """
        This is the same Transformer as the json_parser example.
        """
        @v_args(inline=True)
        def string(self, s):
            return s[1:-1].replace('\\"', '"')

        array = list
        pair = tuple
        object = dict
        number = v_args(inline=True)(float)

        null = lambda self, _: None
        true = lambda self, _: True
        false = lambda self, _: False


    parser = Lark(GRAMMAR, parser='earley', ambiguity="explicit", lexer='dynamic_complete')

    EXAMPLES = [
        r'{_array_:[1,2,3]}',

        r'{_abc_: _array must be of the following format [_1_, _2_, _3_]_}',

        r'{_foo_:{}, _bar_: [], _baz_: __}',

        r'{_error_:_invalid_client_, _error_description_:_AADSTS7000215: Invalid '
        r'client secret is provided.\r\nTrace ID: '
        r'a0a0aaaa-a0a0-0a00-000a-00a00aaa0a00\r\nCorrelation ID: '
        r'aa0aaa00-0aaa-0000-00a0-00000aaaa0aa\r\nTimestamp: 1997-10-10 00:00:00Z_, '
        r'_error_codes_:[7000215], _timestamp_:_1997-10-10 00:00:00Z_, '
        r'_trace_id_:_a0a0aaaa-a0a0-0a00-000a-00a00aaa0a00_, '
        r'_correlation_id_:_aa0aaa00-0aaa-0000-00a0-00000aaaa0aa_, '
        r'_error_uri_:_https://example.com_}',

    ]
    for example in EXAMPLES:
        tree = parser.parse(example)
        tree = RemoveAmbiguities().transform(tree)
        result = TreeToJson().transform(tree)
        pprint(result)


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

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


.. _sphx_glr_download_examples_advanced_dynamic_complete.py:

.. only:: html

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




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

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

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

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


.. only:: html

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

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