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#!/usr/bin/env python
"""Compiles C into assembly for the practicum processor (PP2)
Copyright (C) 2011-2014 Peter Wu <lekensteyn@gmail.com>
Licensed under the MIT license <http://opensource.org/licenses/MIT>.
"""
__author__ = "Peter Wu"
__copyright__ = "Copyright (C) 2011-2014 Peter Wu"
__credits__ = ["Peter Wu"]
__license__ = "MIT"
__version__ = "1.0"
__maintainer__ = "Peter Wu"
__email__ = "lekensteyn@gmail.com"
class LinkedNode(object):
"""Stores nodes with a reference to the parent"""
def __init__(self, node, parent=None, level_increment=False):
"""Holds properties for a node
Keyword arguments:
node -- a Node object which is an object from the c_ast class
parent -- a parent LinkedNode object
level_increment -- True if the indentation level needs to be
incremented, False otherwise
"""
self.node = node
if parent:
assert isinstance(parent, LinkedNode), "parent is not a LinkedNode!"
self.parent = parent
self.function = None
self.break_label = None
self.continue_label = None
self.type = type(node).__name__
self.level = 0
self.variables = None
# for supporting post increment and post decrement
self.post_lines = []
# inherit level and variables from parent
if parent:
self.level = parent.level
self.variables = parent.variables
if level_increment:
self.incrementLevel()
# labels are limited to function contexts
if self.type == "FuncDef":
self.goto_labels = {}
def setVariablesObj(self, variables_obj):
"""Sets a new variables scope object for this node"""
self.variables = variables_obj
def handle_post_lines(self, lines):
"""Add post-increment lines to the lines list and clear the queue"""
lines += self.post_lines
self.post_lines = []
def needNewScope(self):
"""Returns True if a new name scope is necessary and False otherwise"""
if self.type == "Compound":
if self.parent.type not in ("For", "FuncDef"):
return True
elif self.type in ("FileAST", "For", "FuncDef"):
return True
return False
def isTypeStatement(self):
"""Returns True if the node is a statement type"""
return self.type in ("Compound", "If", "Return", "DoWhile", "While",
"For", "Decl", "FuncDef", "Break", "Continue",
"EmptyStatement", "Switch", "DeclList",
"FuncDecl", "ArrayDecl", "Case",
"Default", "EllipsisParam",# (int a, ...)
"Enum", # enum type
"Enumerator", # enum value
"EnumeratorList", # list of enum values
"Goto", "Label", "ParamList", "PtrDecl", "Struct",
"TypeDecl", "Typedef", "Union")
def getStatementNode(self):
"""Returns the nearest LinkedNode which is a statement node type"""
if self.isTypeStatement():
return self
if self.parent:
return self.parent.getStatementNode()
return None
def incrementLevel(self):
self.level += 1
def getFunctionNode(self):
"""Returns the nearest LinkedNode which is a function definition node
type"""
if self.type == "FuncDef":
return self
if self.parent:
return self.parent.getFunctionNode()
return None
def setFunction(self, function):
"""Sets the function object containing label information and a stack
allocation function
"""
self.function = function
function.setLinkedNode(self)
self.variables.setFunction(function)
def getLocation(self):
if hasattr(self.node, "coord"):
return str(self.node.coord)
return "Unknown"
def setBreak(self, break_label):
"""Marks this node as a loop or switch by setting the label for break
Keywords arguments:
break_label -- The label to continue when using the break keyword
"""
self.break_label = break_label
def setContinue(self, continue_label):
"""Marks this node as a loop by setting the label for continue
Keywords arguments:
continue_label -- The label to continue when using the continue keyword
"""
self.continue_label = continue_label
def getBreakNode(self):
"""Returns the label to the end of the nearest switch statement or for
loop"""
if self.break_label is not None:
return self
if self.parent:
return self.parent.getBreakNode()
return None
def getContinueNode(self):
"""Returns the label to the label to continue a loop"""
if self.continue_label is not None:
return self
if self.parent:
return self.parent.getContinueNode()
return None
def setLabel(self, label_name, label_asm):
"""Sets the label for this node
Keyword arguments:
label_name -- The label name as can be used in C
label_asm -- The label as it appears in assembly
"""
if self.parent:
function = self.parent.getFunctionNode()
if not self.parent or not function:
raise RuntimeError("Labels are only allowed in functions")
if label_name in function.goto_labels:
raise RuntimeError("Duplicate label '{}'".format(label_name))
function.goto_labels[label_name] = label_asm
return label_asm
def lookupLabel(self, label_name):
"""Returns the label name as it appears in assembly for label_name"""
# get the nearest function for this node
if self.parent:
function = self.parent.getFunctionNode()
if not self.parent or not function:
raise RuntimeError("Labels are only allowed in functions")
if label_name in function.goto_labels:
return function.goto_labels[label_name]
raise RuntimeError("Label '{}' used but not defined".format(name))
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