def __init__(self, x=(), file=None, **kw):
super(Block, self).__init__(**kw)
self.on_trait_change(self._structure_changed, 'sub_blocks')
self.on_trait_change(self._structure_changed, 'sub_blocks_items')
self.on_trait_change(self._structure_changed, 'ast')
# Interpret arguments:
is_file_object = lambda o: hasattr(o, 'read') and hasattr(o, 'name')
# 'file' -> 'x'
if file is not None:
# Turn 'file' into a file object and move to 'x'
if isinstance(file, basestring):
file = open(file)
elif not is_file_object(file):
raise ValueError("Expected 'file' to be a file or string, "
"got %r" % f)
x = file
# 'x': file object -> string
saved_filename = None
if is_file_object(x):
self.filename = x.name
saved_filename = self.filename
x = x.read()
# 'x' -> 'self.ast' or 'self.sub_blocks'
if isinstance(x, basestring):
# (BlockTransformer handles things like 'import *')
self.ast = parse(x, mode='exec', transformer=BlockTransformer())
elif isinstance(x, Node):
self.ast = x
elif is_sequence(x):
self.sub_blocks = map(to_block, x)
else:
raise ValueError('Expecting string, Node, or sequence. Got %r' % x)
# We really want to keep the filename for "pristine" blocks, and
# _structure_changed nukes it most times
self.filename = saved_filename
def from_string(cls, s):
ast = parse(s, mode='eval', transformer=BlockTransformer())
assert isinstance(ast, compiler.ast.Expression)
v = compiler.walk(ast, NameFinder())
return Expression(ast, v.free, v.locals)