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from __future__ import annotations
from typing import TYPE_CHECKING
from jinja2 import nodes
from jinja2.environment import Environment
from jinja2.parser import Parser
if TYPE_CHECKING:
from collections.abc import Iterator
from jinja2.nodes import Node
env = Environment()
class BooleanParser(Parser):
"""
Only allow condition exprs and/or/not operations.
"""
def parse_compare(self) -> Node:
node: Node
token = self.stream.current
if token.type == 'name':
if token.value in ('true', 'false', 'True', 'False'):
node = nodes.Const(token.value in ('true', 'True'),
lineno=token.lineno)
elif token.value in ('none', 'None'):
node = nodes.Const(None, lineno=token.lineno)
else:
node = nodes.Name(token.value, 'load', lineno=token.lineno)
next(self.stream)
elif token.type == 'lparen':
next(self.stream)
node = self.parse_expression()
self.stream.expect('rparen')
else:
self.fail(f"unexpected token '{token}'", token.lineno)
return node
class Tags:
def __init__(self, tags: list[str] | None = None) -> None:
self.tags = dict.fromkeys(tags or [], True)
def has(self, tag: str) -> bool:
return tag in self.tags
__contains__ = has
def __iter__(self) -> Iterator[str]:
return iter(self.tags)
def add(self, tag: str) -> None:
self.tags[tag] = True
def remove(self, tag: str) -> None:
self.tags.pop(tag, None)
def eval_condition(self, condition: str) -> bool:
# exceptions are handled by the caller
parser = BooleanParser(env, condition, state='variable')
expr = parser.parse_expression()
if not parser.stream.eos:
msg = 'chunk after expression'
raise ValueError(msg)
def eval_node(node: Node) -> bool:
if isinstance(node, nodes.CondExpr):
if eval_node(node.test):
return eval_node(node.expr1)
else:
return eval_node(node.expr2)
elif isinstance(node, nodes.And):
return eval_node(node.left) and eval_node(node.right)
elif isinstance(node, nodes.Or):
return eval_node(node.left) or eval_node(node.right)
elif isinstance(node, nodes.Not):
return not eval_node(node.node)
elif isinstance(node, nodes.Name):
return self.tags.get(node.name, False)
else:
msg = 'invalid node, check parsing'
raise ValueError(msg)
return eval_node(expr)
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