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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.
class NodeVisitor(object):
def visit(self, node):
# This is ugly as hell, but we don't have multimethods and
# they aren't trivial to fake without access to the class
# object from the class body
func = getattr(self, "visit_%s" % (node.__class__.__name__))
return func(node)
class Node(object):
def __init__(self, data=None):
self.data = data
self.parent = None
self.children = []
def append(self, other):
other.parent = self
self.children.append(other)
def remove(self):
self.parent.children.remove(self)
def __repr__(self):
return "<%s %s>" % (self.__class__.__name__, self.data)
def __str__(self):
rv = [repr(self)]
for item in self.children:
rv.extend(" %s" % line for line in str(item).split("\n"))
return "\n".join(rv)
def __eq__(self, other):
if not (self.__class__ == other.__class__ and
self.data == other.data and
len(self.children) == len(other.children)):
return False
for child, other_child in zip(self.children, other.children):
if not child == other_child:
return False
return True
def copy(self):
new = self.__class__(self.data)
for item in self.children:
new.append(item.copy())
return new
class DataNode(Node):
def append(self, other):
# Append that retains the invariant that child data nodes
# come after child nodes of other types
other.parent = self
if isinstance(other, DataNode):
self.children.append(other)
else:
index = len(self.children)
while index > 0 and isinstance(self.children[index - 1], DataNode):
index -= 1
for i in xrange(index):
assert other.data != self.children[i].data
self.children.insert(index, other)
class KeyValueNode(Node):
def append(self, other):
# Append that retains the invariant that conditional nodes
# come before unconditional nodes
other.parent = self
if isinstance(other, ValueNode):
if self.children:
assert not isinstance(self.children[-1], ValueNode)
self.children.append(other)
else:
if self.children and isinstance(self.children[-1], ValueNode):
self.children.insert(len(self.children) - 1, other)
else:
self.children.append(other)
class ListNode(Node):
def append(self, other):
other.parent = self
self.children.append(other)
class ValueNode(Node):
def append(self, other):
raise TypeError
class AtomNode(ValueNode):
pass
class ConditionalNode(Node):
pass
class UnaryExpressionNode(Node):
def __init__(self, operator, operand):
Node.__init__(self)
self.append(operator)
self.append(operand)
def append(self, other):
Node.append(self, other)
assert len(self.children) <= 2
def copy(self):
new = self.__class__(self.children[0].copy(),
self.children[1].copy())
return new
class BinaryExpressionNode(Node):
def __init__(self, operator, operand_0, operand_1):
Node.__init__(self)
self.append(operator)
self.append(operand_0)
self.append(operand_1)
def append(self, other):
Node.append(self, other)
assert len(self.children) <= 3
def copy(self):
new = self.__class__(self.children[0].copy(),
self.children[1].copy(),
self.children[2].copy())
return new
class UnaryOperatorNode(Node):
def append(self, other):
raise TypeError
class BinaryOperatorNode(Node):
def append(self, other):
raise TypeError
class IndexNode(Node):
pass
class VariableNode(Node):
pass
class StringNode(Node):
pass
class NumberNode(ValueNode):
pass
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