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import unittest
from tatsu.exceptions import FailedSemantics
from tatsu.grammars import ModelContext
from tatsu.tool import compile
class StatefulTests(unittest.TestCase):
def test_stateful(self):
# Parser for mediawiki-style unordered lists.
grammar = r"""
document = @:ul [ nl ] $ ;
ul = "*" ul_start el+:li { nl el:li } * ul_end ;
li = ul | li_text ;
(* Quirk: If a text line is followed by a sublist, the sublist does not get its own li. *)
li_text = text:text [ ul:li_followed_by_ul ] ;
li_followed_by_ul = nl @:ul ;
text = ?/.*/? ;
nl = ?/\n/? ul_marker ;
(* The following rules are placeholders for state transitions. *)
ul_start = () ;
ul_end = () ;
(* The following rules are placeholders for state validations and grammar rules. *)
ul_marker = () ;
"""
class StatefulSemantics:
def __init__(self, parser):
self._context = parser
def ul_start(self, ast):
ctx = self._context
ctx.substate = 1 if ctx.substate is None else ctx.substate + 1
return ast
def ul_end(self, ast):
ctx = self._context
ctx.substate = (
None
if ctx.substate is None or ctx.substate <= 1
else ctx.substate - 1
)
return ast
def ul_marker(self, ast):
ctx = self._context
if ctx.substate is not None and not ctx.tokenizer.match(
'*' * ctx.substate,
):
raise FailedSemantics('not at correct level')
return ast
def ul(self, ast):
return '<ul>' + ''.join(ast.el) + '</ul>'
def li(self, ast):
return '<li>' + ast + '</li>'
def li_text(self, ast):
return ast.text if ast.ul is None else ast.text + ast.ul
model = compile(grammar, 'test')
context = ModelContext(model.rules, whitespace='', nameguard=False)
ast = model.parse(
'*abc',
start='document',
ctx=context,
semantics=StatefulSemantics(context),
whitespace='',
nameguard=False,
)
self.assertEqual(ast, '<ul><li>abc</li></ul>')
ast = model.parse(
'*abc\n',
start='document',
ctx=context,
semantics=StatefulSemantics(context),
whitespace='',
nameguard=False,
)
self.assertEqual('<ul><li>abc</li></ul>', ast)
ast = model.parse(
'*abc\n*def\n',
start='document',
ctx=context,
semantics=StatefulSemantics(context),
whitespace='',
nameguard=False,
)
self.assertEqual('<ul><li>abc</li><li>def</li></ul>', ast)
ast = model.parse(
'**abc',
start='document',
ctx=context,
semantics=StatefulSemantics(context),
whitespace='',
nameguard=False,
)
self.assertEqual('<ul><li><ul><li>abc</li></ul></li></ul>', ast)
ast = model.parse(
'*abc\n**def\n',
start='document',
ctx=context,
semantics=StatefulSemantics(context),
whitespace='',
nameguard=False,
)
self.assertEqual('<ul><li>abc<ul><li>def</li></ul></li></ul>', ast)
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