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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/.
import operator
from ..node import NodeVisitor
from ..parser import parse
class Compiler(NodeVisitor):
"""Compiler backend that evaluates conditional expressions
to give static output"""
def compile(self, tree, expr_data, data_cls_getter=None, **kwargs):
"""Compile a raw AST into a form with conditional expressions
evaluated.
tree - The root node of the wptmanifest AST to compile
expr_data - A dictionary of key / value pairs to use when
evaluating conditional expressions
data_cls_getter - A function taking two parameters; the previous
output node and the current ast node and returning
the class of the output node to use for the current
ast node
"""
self._kwargs = kwargs
self.expr_data = expr_data
if data_cls_getter is None:
self.data_cls_getter = lambda x, y: ManifestItem
else:
self.data_cls_getter = data_cls_getter
self.output_node = None
self.visit(tree)
return self.output_node
def visit_DataNode(self, node):
output_parent = self.output_node
if self.output_node is None:
assert node.parent is None
self.output_node = self.data_cls_getter(None, None)(None, **self._kwargs)
else:
self.output_node = self.data_cls_getter(self.output_node, node)(node.data)
for child in node.children:
self.visit(child)
if output_parent is not None:
output_parent.append(self.output_node)
self.output_node = self.output_node.parent
def visit_KeyValueNode(self, node):
key_name = node.data
key_value = None
for child in node.children:
value = self.visit(child)
if value is not None:
key_value = value
break
if key_value is not None:
self.output_node.set(key_name, key_value)
def visit_ValueNode(self, node):
return node.data
def visit_AtomNode(self, node):
return node.data
def visit_ListNode(self, node):
return [self.visit(child) for child in node.children]
def visit_ConditionalNode(self, node):
assert len(node.children) == 2
if self.visit(node.children[0]):
return self.visit(node.children[1])
def visit_StringNode(self, node):
value = node.data
for child in node.children:
value = self.visit(child)(value)
return value
def visit_NumberNode(self, node):
if "." in node.data:
return float(node.data)
else:
return int(node.data)
def visit_VariableNode(self, node):
value = self.expr_data[node.data]
for child in node.children:
value = self.visit(child)(value)
return value
def visit_IndexNode(self, node):
assert len(node.children) == 1
index = self.visit(node.children[0])
return lambda x: x[index]
def visit_UnaryExpressionNode(self, node):
assert len(node.children) == 2
operator = self.visit(node.children[0])
operand = self.visit(node.children[1])
return operator(operand)
def visit_BinaryExpressionNode(self, node):
assert len(node.children) == 3
operator = self.visit(node.children[0])
operand_0 = self.visit(node.children[1])
operand_1 = self.visit(node.children[2])
return operator(operand_0, operand_1)
def visit_UnaryOperatorNode(self, node):
return {"not": operator.not_}[node.data]
def visit_BinaryOperatorNode(self, node):
return {"and": operator.and_,
"or": operator.or_,
"==": operator.eq,
"!=": operator.ne}[node.data]
class ManifestItem(object):
def __init__(self, name, **kwargs):
self.parent = None
self.name = name
self.children = []
self._data = {}
def __repr__(self):
return "<ManifestItem %s>" % (self.name)
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)
@property
def is_empty(self):
if self._data:
return False
return all(child.is_empty for child in self.children)
@property
def root(self):
node = self
while node.parent is not None:
node = node.parent
return node
def has_key(self, key):
for node in [self, self.root]:
if key in node._data:
return True
return False
def get(self, key):
for node in [self, self.root]:
if key in node._data:
return node._data[key]
raise KeyError
def set(self, name, value):
self._data[name] = value
def remove(self):
if self.parent:
self.parent._remove_child(self)
def _remove_child(self, child):
self.children.remove(child)
child.parent = None
def iterchildren(self, name=None):
for item in self.children:
if item.name == name or name is None:
yield item
def _flatten(self):
rv = {}
for node in [self, self.root]:
for name, value in node._data.iteritems():
if name not in rv:
rv[name] = value
return rv
def iteritems(self):
for item in self._flatten().iteritems():
yield item
def iterkeys(self):
for item in self._flatten().iterkeys():
yield item
def itervalues(self):
for item in self._flatten().itervalues():
yield item
def append(self, child):
child.parent = self
self.children.append(child)
return child
def compile_ast(ast, expr_data, data_cls_getter=None, **kwargs):
return Compiler().compile(ast,
expr_data,
data_cls_getter=data_cls_getter,
**kwargs)
def compile(stream, expr_data, data_cls_getter=None, **kwargs):
return compile_ast(parse(stream),
expr_data,
data_cls_getter=data_cls_getter,
**kwargs)
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