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# Copyright (c) 2017-2026 Juancarlo Añez (apalala@gmail.com)
# SPDX-License-Identifier: BSD-4-Clause
from __future__ import annotations
from collections import defaultdict
import tatsu
from tatsu.util import asjsons
from tatsu.walkers import BreadthFirstWalker, DepthFirstWalker, NodeWalker
def test_walk_node_ast():
GRAMMAR = r"""
@@grammar::TLA
#
# comment
#
start = expression $;
expression = temporal_expression | nontemporal_top_expression ;
nontemporal_top_expression(SampleExpression) = expr:nontemporal_expression ;
temporal_expression = temporal_atom;
temporal_atom(TemporalSeq) = ['Seq'] '(' @:temporal_arg_list ')';
temporal_arg_list = "," .{@+:expression}+;
nontemporal_expression(Number) = number ;
# tokens
number::int = /\d+/;
"""
parser = tatsu.compile(GRAMMAR, asmodel=True)
model = parser.parse('Seq(1,1)')
assert model.ast is not None
seen = defaultdict(int)
class PW(DepthFirstWalker):
def walk_Node(self, node, *args, **kwargs):
t = type(node).__name__
print(f'node {t}')
seen[t] += 1
print(asjsons(model))
PW().walk(model)
assert dict(seen) == {'SampleExpression': 2, 'TemporalSeq': 1, 'Number': 2}
walker = BreadthFirstWalker()
result = tuple(type(n).__name__ for n in walker.walk(model))
assert result == (
'TemporalSeq',
'SampleExpression',
'SampleExpression',
'Number',
'Number',
)
walker = DepthFirstWalker()
result = tuple(type(n).__name__ for n in walker.walk(model))
assert result == (
'TemporalSeq',
'SampleExpression',
'Number',
'SampleExpression',
'Number',
)
def test_cache_per_class():
class PW(DepthFirstWalker):
pass
assert isinstance(NodeWalker._walker_cache, dict)
assert isinstance(DepthFirstWalker._walker_cache, dict)
assert isinstance(PW._walker_cache, dict)
assert id(NodeWalker._walker_cache) != id(DepthFirstWalker.walker_cache)
assert id(PW._walker_cache) != id(DepthFirstWalker._walker_cache)
walker = PW()
assert id(walker.walker_cache) == id(PW._walker_cache)
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