# mako/pyparser.py
# Copyright 2006-2022 the Mako authors and contributors <see AUTHORS file>
#
# This module is part of Mako and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Handles parsing of Python code.
Parsing to AST is done via _ast on Python > 2.5, otherwise the compiler
module is used.
"""
import operator
import _ast
from mako import _ast_util
from mako import compat
from mako import exceptions
from mako import util
# words that cannot be assigned to (notably
# smaller than the total keys in __builtins__)
reserved = {"True", "False", "None", "print"}
# the "id" attribute on a function node
arg_id = operator.attrgetter("arg")
util.restore__ast(_ast)
def parse(code, mode="exec", **exception_kwargs):
"""Parse an expression into AST"""
try:
return _ast_util.parse(code, "<unknown>", mode)
except Exception as e:
raise exceptions.SyntaxException(
"(%s) %s (%r)"
% (
compat.exception_as().__class__.__name__,
compat.exception_as(),
code[0:50],
),
**exception_kwargs,
) from e
class FindIdentifiers(_ast_util.NodeVisitor):
def __init__(self, listener, **exception_kwargs):
self.in_function = False
self.in_assign_targets = False
self.local_ident_stack = set()
self.listener = listener
self.exception_kwargs = exception_kwargs
def _add_declared(self, name):
if not self.in_function:
self.listener.declared_identifiers.add(name)
else:
self.local_ident_stack.add(name)
def visit_ClassDef(self, node):
self._add_declared(node.name)
def visit_Assign(self, node):
# flip around the visiting of Assign so the expression gets
# evaluated first, in the case of a clause like "x=x+5" (x
# is undeclared)
self.visit(node.value)
in_a = self.in_assign_targets
self.in_assign_targets = True
for n in node.targets:
self.visit(n)
self.in_assign_targets = in_a
def visit_ExceptHandler(self, node):
if node.name is not None:
self._add_declared(node.name)
if node.type is not None:
self.visit(node.type)
for statement in node.body:
self.visit(statement)
def visit_Lambda(self, node, *args):
self._visit_function(node, True)
def visit_FunctionDef(self, node):
self._add_declared(node.name)
self._visit_function(node, False)
def _expand_tuples(self, args):
for arg in args:
if isinstance(arg, _ast.Tuple):
yield from arg.elts
else:
yield arg
def _visit_function(self, node, islambda):
# push function state onto stack. dont log any more
# identifiers as "declared" until outside of the function,
# but keep logging identifiers as "undeclared". track
# argument names in each function header so they arent
# counted as "undeclared"
inf = self.in_function
self.in_function = True
local_ident_stack = self.local_ident_stack
self.local_ident_stack = local_ident_stack.union(
[arg_id(arg) for arg in self._expand_tuples(node.args.args)]
)
if islambda:
self.visit(node.body)
else:
for n in node.body:
self.visit(n)
self.in_function = inf
self.local_ident_stack = local_ident_stack
def visit_For(self, node):
# flip around visit
self.visit(node.iter)
self.visit(node.target)
for statement in node.body:
self.visit(statement)
for statement in node.orelse:
self.visit(statement)
def visit_Name(self, node):
if isinstance(node.ctx, _ast.Store):
# this is eqiuvalent to visit_AssName in
# compiler
self._add_declared(node.id)
elif (
node.id not in reserved
and node.id not in self.listener.declared_identifiers
and node.id not in self.local_ident_stack
):
self.listener.undeclared_identifiers.add(node.id)
def visit_Import(self, node):
for name in node.names:
if name.asname is not None:
self._add_declared(name.asname)
else:
self._add_declared(name.name.split(".")[0])
def visit_ImportFrom(self, node):
for name in node.names:
if name.asname is not None:
self._add_declared(name.asname)
elif name.name == "*":
raise exceptions.CompileException(
"'import *' is not supported, since all identifier "
"names must be explicitly declared. Please use the "
"form 'from <modulename> import <name1>, <name2>, "
"...' instead.",
**self.exception_kwargs,
)
else:
self._add_declared(name.name)
class FindTuple(_ast_util.NodeVisitor):
def __init__(self, listener, code_factory, **exception_kwargs):
self.listener = listener
self.exception_kwargs = exception_kwargs
self.code_factory = code_factory
def visit_Tuple(self, node):
for n in node.elts:
p = self.code_factory(n, **self.exception_kwargs)
self.listener.codeargs.append(p)
self.listener.args.append(ExpressionGenerator(n).value())
ldi = self.listener.declared_identifiers
self.listener.declared_identifiers = ldi.union(
p.declared_identifiers
)
lui = self.listener.undeclared_identifiers
self.listener.undeclared_identifiers = lui.union(
p.undeclared_identifiers
)
class ParseFunc(_ast_util.NodeVisitor):
def __init__(self, listener, **exception_kwargs):
self.listener = listener
self.exception_kwargs = exception_kwargs
def visit_FunctionDef(self, node):
self.listener.funcname = node.name
argnames = [arg_id(arg) for arg in node.args.args]
if node.args.vararg:
argnames.append(node.args.vararg.arg)
kwargnames = [arg_id(arg) for arg in node.args.kwonlyargs]
if node.args.kwarg:
kwargnames.append(node.args.kwarg.arg)
self.listener.argnames = argnames
self.listener.defaults = node.args.defaults # ast
self.listener.kwargnames = kwargnames
self.listener.kwdefaults = node.args.kw_defaults
self.listener.varargs = node.args.vararg
self.listener.kwargs = node.args.kwarg
class ExpressionGenerator:
def __init__(self, astnode):
self.generator = _ast_util.SourceGenerator(" " * 4)
self.generator.visit(astnode)
def value(self):
return "".join(self.generator.result)
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