gitmirror/examples/conf_nolex.py

#
# This example demonstrates scanless parsing using the earley_nolex frontend
#
# Using a lexer for configuration files is tricky, because values don't
# have to be surrounded by delimiters.
# In this example with skip lexing and let the Earley parser resolve the ambiguity.
#
# Future versions of lark will make it easier to write these kinds of grammars.
#
# Another approach is to use the contextual lexer. It is less powerful than the scanless approach,
# but it can handle some ambiguity in lexing and it's much faster since it uses LALR(1).
# See examples/conf.py for an example of that approach.
#


from lark import Lark

parser = Lark(r"""
        start: _NL? section+
        section: "[" NAME "]" _NL item+
        item: NAME "=" VALUE _NL
        VALUE: /./*
        %import common.CNAME -> NAME
        %import common.NEWLINE -> _NL

        %import common.WS_INLINE
        %ignore WS_INLINE
    """, lexer=None)

def test():
    sample_conf = """
[bla]

a=Hello
this="that",4
"""

    r = parser.parse(sample_conf)
    print (r.pretty())

if __name__ == '__main__':
    test()