def visitTryExcept(self, node):
# If we are code after a 'try' block, then it either succeeded or
# handled its own exception. So either the 'try' and 'else' blocks ran,
# or some of the 'try' and one of the handlers ran. If we treat the
# 'try' and 'else' blocks as one, then we can say that
# 'try'/'except'/'else' produces unconditional locals when the same
# name is local to 'try'/'else' and every handler. All other bindings
# are conditional.
# Visit children
body_v = walk([node.body, node.else_], NameFinder())
# (A handler is (type, name, body) where 'type' and 'name' can be None)
handler_vs = [ walk(h, NameFinder()) for h in node.handlers ]
assert all(not v.conditional_locals for v in handler_vs)
# Free names come from 'try', 'else', and names in 'except' that aren't
# bound by the exception name. Since 'handlers' bundles each 'except'
# body with its exception name, the bindings are already computed.
self._see_unbound(body_v.free | union(v.free for v in handler_vs))
# Unconditional locals only come from locals in both the 'try'/'else'
# body and every 'except' body. All other locals are conditional.
locals = body_v.locals & intersect(v.locals for v in handler_vs)
conditional_locals = \
(body_v.all_locals() | union(v.all_locals() for v in handler_vs)) \
- locals
self._bind(locals)
self._bind_conditional(conditional_locals)
def visitTryExcept(self, node):
# If we are code after a 'try' block, then it either succeeded or
# handled its own exception. So either the 'try' and 'else' blocks ran,
# or some of the 'try' and one of the handlers ran. If we treat the
# 'try' and 'else' blocks as one, then we can say that
# 'try'/'except'/'else' produces unconditional locals when the same
# name is local to 'try'/'else' and every handler. All other bindings
# are conditional.
# Visit children
body_v = walk([node.body, node.else_], NameFinder())
# (A handler is (type, name, body) where 'type' and 'name' can be None)
handler_vs = [walk(h, NameFinder()) for h in node.handlers]
assert all(not v.conditional_locals for v in handler_vs)
# Free names come from 'try', 'else', and names in 'except' that aren't
# bound by the exception name. Since 'handlers' bundles each 'except'
# body with its exception name, the bindings are already computed.
self._see_unbound(body_v.free | union(v.free for v in handler_vs))
# Unconditional locals only come from locals in both the 'try'/'else'
# body and every 'except' body. All other locals are conditional.
locals = body_v.locals & intersect(v.locals for v in handler_vs)
conditional_locals = \
(body_v.all_locals() | union(v.all_locals() for v in handler_vs)) \
- locals
self._bind(locals)
self._bind_conditional(conditional_locals)
def is_const(ast):
''' Whether an AST represents a constant expression.
I'm not sure what "constant" means yet, but here are some examples:
>>> all(is_const(parse(s, mode='eval')) for s in (
... '0',
... 'True',
... 'None',
... '"foo"',
... '[1,2]',
... '(False, [])',
... '{"a": 1}',
... '{"a": 0, (True, False): [None, 3, "fish", ()]}',
... ))
True
And some non-examples, some of which maybe should be reclassified:
>>> any(is_const(parse(s, mode='eval')) for s in (
... '0+1',
... '~8',
... '0 < 1',
... 'not True',
... '"fo%s" % "o"',
... 'len([1,2])',
... '[1,2][0]',
... '[1,a]',
... '[a for a in [1,2]]',
... '{"a": 0}.keys()',
... 'set()',
... 'list()',
... 'dict()',
... 'dict',
... 'lambda: 3',
... 'lambda a: a',
... ))
False
'''
return (
isinstance(ast, Const) or
isinstance(ast, Name) and ast.name in ['None', 'True', 'False'] or
isinstance(ast, (List, Tuple, Dict)) and all(map(is_const, ast)) or
isinstance(ast, Expression) and is_const(ast.node)
)
def is_const(ast):
''' Whether an AST represents a constant expression.
I'm not sure what "constant" means yet, but here are some examples:
>>> all(is_const(parse(s, mode='eval')) for s in (
... '0',
... 'True',
... 'None',
... '"foo"',
... '[1,2]',
... '(False, [])',
... '{"a": 1}',
... '{"a": 0, (True, False): [None, 3, "fish", ()]}',
... ))
True
And some non-examples, some of which maybe should be reclassified:
>>> any(is_const(parse(s, mode='eval')) for s in (
... '0+1',
... '~8',
... '0 < 1',
... 'not True',
... '"fo%s" % "o"',
... 'len([1,2])',
... '[1,2][0]',
... '[1,a]',
... '[a for a in [1,2]]',
... '{"a": 0}.keys()',
... 'set()',
... 'list()',
... 'dict()',
... 'dict',
... 'lambda: 3',
... 'lambda a: a',
... ))
False
'''
return (isinstance(ast, Const)
or isinstance(ast, Name) and ast.name in ['None', 'True', 'False']
or isinstance(ast, (List, Tuple, Dict)) and all(map(is_const, ast))
or isinstance(ast, Expression) and is_const(ast.node))
