diff --git a/bitbake/lib/codegen.py b/bitbake/lib/codegen.py
new file mode 100644
index 0000000..be772d5
--- /dev/null
+++ b/bitbake/lib/codegen.py
@@ -0,0 +1,570 @@
+# -*- coding: utf-8 -*-
+"""
+    codegen
+    ~~~~~~~
+
+    Extension to ast that allow ast -> python code generation.
+
+    :copyright: Copyright 2008 by Armin Ronacher.
+    :license: BSD.
+"""
+from ast import *
+
+BOOLOP_SYMBOLS = {
+    And:        'and',
+    Or:         'or'
+}
+
+BINOP_SYMBOLS = {
+    Add:        '+',
+    Sub:        '-',
+    Mult:       '*',
+    Div:        '/',
+    FloorDiv:   '//',
+    Mod:        '%',
+    LShift:     '<<',
+    RShift:     '>>',
+    BitOr:      '|',
+    BitAnd:     '&',
+    BitXor:     '^'
+}
+
+CMPOP_SYMBOLS = {
+    Eq:         '==',
+    Gt:         '>',
+    GtE:        '>=',
+    In:         'in',
+    Is:         'is',
+    IsNot:      'is not',
+    Lt:         '<',
+    LtE:        '<=',
+    NotEq:      '!=',
+    NotIn:      'not in'
+}
+
+UNARYOP_SYMBOLS = {
+    Invert:     '~',
+    Not:        'not',
+    UAdd:       '+',
+    USub:       '-'
+}
+
+ALL_SYMBOLS = {}
+ALL_SYMBOLS.update(BOOLOP_SYMBOLS)
+ALL_SYMBOLS.update(BINOP_SYMBOLS)
+ALL_SYMBOLS.update(CMPOP_SYMBOLS)
+ALL_SYMBOLS.update(UNARYOP_SYMBOLS)
+
+def to_source(node, indent_with=' ' * 4, add_line_information=False):
+    """This function can convert a node tree back into python sourcecode.
+    This is useful for debugging purposes, especially if you're dealing with
+    custom asts not generated by python itself.
+
+    It could be that the sourcecode is evaluable when the AST itself is not
+    compilable / evaluable.  The reason for this is that the AST contains some
+    more data than regular sourcecode does, which is dropped during
+    conversion.
+
+    Each level of indentation is replaced with `indent_with`.  Per default this
+    parameter is equal to four spaces as suggested by PEP 8, but it might be
+    adjusted to match the application's styleguide.
+
+    If `add_line_information` is set to `True` comments for the line numbers
+    of the nodes are added to the output.  This can be used to spot wrong line
+    number information of statement nodes.
+    """
+    generator = SourceGenerator(indent_with, add_line_information)
+    generator.visit(node)
+    return ''.join(generator.result)
+
+
+class SourceGenerator(NodeVisitor):
+    """This visitor is able to transform a well formed syntax tree into python
+    sourcecode.  For more details have a look at the docstring of the
+    `node_to_source` function.
+    """
+
+    def __init__(self, indent_with, add_line_information=False):
+        self.result = []
+        self.indent_with = indent_with
+        self.add_line_information = add_line_information
+        self.indentation = 0
+        self.new_lines = 0
+
+    def write(self, x):
+        if self.new_lines:
+            if self.result:
+                self.result.append('\n' * self.new_lines)
+            self.result.append(self.indent_with * self.indentation)
+            self.new_lines = 0
+        self.result.append(x)
+
+    def newline(self, node=None, extra=0):
+        self.new_lines = max(self.new_lines, 1 + extra)
+        if node is not None and self.add_line_information:
+            self.write('# line: %s' % node.lineno)
+            self.new_lines = 1
+
+    def body(self, statements):
+        self.new_line = True
+        self.indentation += 1
+        for stmt in statements:
+            self.visit(stmt)
+        self.indentation -= 1
+
+    def body_or_else(self, node):
+        self.body(node.body)
+        if node.orelse:
+            self.newline()
+            self.write('else:')
+            self.body(node.orelse)
+
+    def signature(self, node):
+        want_comma = []
+        def write_comma():
+            if want_comma:
+                self.write(', ')
+            else:
+                want_comma.append(True)
+
+        padding = [None] * (len(node.args) - len(node.defaults))
+        for arg, default in zip(node.args, padding + node.defaults):
+            write_comma()
+            self.visit(arg)
+            if default is not None:
+                self.write('=')
+                self.visit(default)
+        if node.vararg is not None:
+            write_comma()
+            self.write('*' + node.vararg)
+        if node.kwarg is not None:
+            write_comma()
+            self.write('**' + node.kwarg)
+
+    def decorators(self, node):
+        for decorator in node.decorator_list:
+            self.newline(decorator)
+            self.write('@')
+            self.visit(decorator)
+
+    # Statements
+
+    def visit_Assign(self, node):
+        self.newline(node)
+        for idx, target in enumerate(node.targets):
+            if idx:
+                self.write(', ')
+            self.visit(target)
+        self.write(' = ')
+        self.visit(node.value)
+
+    def visit_AugAssign(self, node):
+        self.newline(node)
+        self.visit(node.target)
+        self.write(BINOP_SYMBOLS[type(node.op)] + '=')
+        self.visit(node.value)
+
+    def visit_ImportFrom(self, node):
+        self.newline(node)
+        self.write('from %s%s import ' % ('.' * node.level, node.module))
+        for idx, item in enumerate(node.names):
+            if idx:
+                self.write(', ')
+            self.write(item)
+
+    def visit_Import(self, node):
+        self.newline(node)
+        for item in node.names:
+            self.write('import ')
+            self.visit(item)
+
+    def visit_Expr(self, node):
+        self.newline(node)
+        self.generic_visit(node)
+
+    def visit_FunctionDef(self, node):
+        self.newline(extra=1)
+        self.decorators(node)
+        self.newline(node)
+        self.write('def %s(' % node.name)
+        self.signature(node.args)
+        self.write('):')
+        self.body(node.body)
+
+    def visit_ClassDef(self, node):
+        have_args = []
+        def paren_or_comma():
+            if have_args:
+                self.write(', ')
+            else:
+                have_args.append(True)
+                self.write('(')
+
+        self.newline(extra=2)
+        self.decorators(node)
+        self.newline(node)
+        self.write('class %s' % node.name)
+        for base in node.bases:
+            paren_or_comma()
+            self.visit(base)
+        # XXX: the if here is used to keep this module compatible
+        #      with python 2.6.
+        if hasattr(node, 'keywords'):
+            for keyword in node.keywords:
+                paren_or_comma()
+                self.write(keyword.arg + '=')
+                self.visit(keyword.value)
+            if node.starargs is not None:
+                paren_or_comma()
+                self.write('*')
+                self.visit(node.starargs)
+            if node.kwargs is not None:
+                paren_or_comma()
+                self.write('**')
+                self.visit(node.kwargs)
+        self.write(have_args and '):' or ':')
+        self.body(node.body)
+
+    def visit_If(self, node):
+        self.newline(node)
+        self.write('if ')
+        self.visit(node.test)
+        self.write(':')
+        self.body(node.body)
+        while True:
+            else_ = node.orelse
+            if len(else_) == 1 and isinstance(else_[0], If):
+                node = else_[0]
+                self.newline()
+                self.write('elif ')
+                self.visit(node.test)
+                self.write(':')
+                self.body(node.body)
+            else:
+                self.newline()
+                self.write('else:')
+                self.body(else_)
+                break
+
+    def visit_For(self, node):
+        self.newline(node)
+        self.write('for ')
+        self.visit(node.target)
+        self.write(' in ')
+        self.visit(node.iter)
+        self.write(':')
+        self.body_or_else(node)
+
+    def visit_While(self, node):
+        self.newline(node)
+        self.write('while ')
+        self.visit(node.test)
+        self.write(':')
+        self.body_or_else(node)
+
+    def visit_With(self, node):
+        self.newline(node)
+        self.write('with ')
+        self.visit(node.context_expr)
+        if node.optional_vars is not None:
+            self.write(' as ')
+            self.visit(node.optional_vars)
+        self.write(':')
+        self.body(node.body)
+
+    def visit_Pass(self, node):
+        self.newline(node)
+        self.write('pass')
+
+    def visit_Print(self, node):
+        # XXX: python 2.6 only
+        self.newline(node)
+        self.write('print ')
+        want_comma = False
+        if node.dest is not None:
+            self.write(' >> ')
+            self.visit(node.dest)
+            want_comma = True
+        for value in node.values:
+            if want_comma:
+                self.write(', ')
+            self.visit(value)
+            want_comma = True
+        if not node.nl:
+            self.write(',')
+
+    def visit_Delete(self, node):
+        self.newline(node)
+        self.write('del ')
+        for idx, target in enumerate(node):
+            if idx:
+                self.write(', ')
+            self.visit(target)
+
+    def visit_TryExcept(self, node):
+        self.newline(node)
+        self.write('try:')
+        self.body(node.body)
+        for handler in node.handlers:
+            self.visit(handler)
+
+    def visit_TryFinally(self, node):
+        self.newline(node)
+        self.write('try:')
+        self.body(node.body)
+        self.newline(node)
+        self.write('finally:')
+        self.body(node.finalbody)
+
+    def visit_Global(self, node):
+        self.newline(node)
+        self.write('global ' + ', '.join(node.names))
+
+    def visit_Nonlocal(self, node):
+        self.newline(node)
+        self.write('nonlocal ' + ', '.join(node.names))
+
+    def visit_Return(self, node):
+        self.newline(node)
+        self.write('return ')
+        self.visit(node.value)
+
+    def visit_Break(self, node):
+        self.newline(node)
+        self.write('break')
+
+    def visit_Continue(self, node):
+        self.newline(node)
+        self.write('continue')
+
+    def visit_Raise(self, node):
+        # XXX: Python 2.6 / 3.0 compatibility
+        self.newline(node)
+        self.write('raise')
+        if hasattr(node, 'exc') and node.exc is not None:
+            self.write(' ')
+            self.visit(node.exc)
+            if node.cause is not None:
+                self.write(' from ')
+                self.visit(node.cause)
+        elif hasattr(node, 'type') and node.type is not None:
+            self.visit(node.type)
+            if node.inst is not None:
+                self.write(', ')
+                self.visit(node.inst)
+            if node.tback is not None:
+                self.write(', ')
+                self.visit(node.tback)
+
+    # Expressions
+
+    def visit_Attribute(self, node):
+        self.visit(node.value)
+        self.write('.' + node.attr)
+
+    def visit_Call(self, node):
+        want_comma = []
+        def write_comma():
+            if want_comma:
+                self.write(', ')
+            else:
+                want_comma.append(True)
+
+        self.visit(node.func)
+        self.write('(')
+        for arg in node.args:
+            write_comma()
+            self.visit(arg)
+        for keyword in node.keywords:
+            write_comma()
+            self.write(keyword.arg + '=')
+            self.visit(keyword.value)
+        if node.starargs is not None:
+            write_comma()
+            self.write('*')
+            self.visit(node.starargs)
+        if node.kwargs is not None:
+            write_comma()
+            self.write('**')
+            self.visit(node.kwargs)
+        self.write(')')
+
+    def visit_Name(self, node):
+        self.write(node.id)
+
+    def visit_Str(self, node):
+        self.write(repr(node.s))
+
+    def visit_Bytes(self, node):
+        self.write(repr(node.s))
+
+    def visit_Num(self, node):
+        self.write(repr(node.n))
+
+    def visit_Tuple(self, node):
+        self.write('(')
+        idx = -1
+        for idx, item in enumerate(node.elts):
+            if idx:
+                self.write(', ')
+            self.visit(item)
+        self.write(idx and ')' or ',)')
+
+    def sequence_visit(left, right):
+        def visit(self, node):
+            self.write(left)
+            for idx, item in enumerate(node.elts):
+                if idx:
+                    self.write(', ')
+                self.visit(item)
+            self.write(right)
+        return visit
+
+    visit_List = sequence_visit('[', ']')
+    visit_Set = sequence_visit('{', '}')
+    del sequence_visit
+
+    def visit_Dict(self, node):
+        self.write('{')
+        for idx, (key, value) in enumerate(zip(node.keys, node.values)):
+            if idx:
+                self.write(', ')
+            self.visit(key)
+            self.write(': ')
+            self.visit(value)
+        self.write('}')
+
+    def visit_BinOp(self, node):
+        self.visit(node.left)
+        self.write(' %s ' % BINOP_SYMBOLS[type(node.op)])
+        self.visit(node.right)
+
+    def visit_BoolOp(self, node):
+        self.write('(')
+        for idx, value in enumerate(node.values):
+            if idx:
+                self.write(' %s ' % BOOLOP_SYMBOLS[type(node.op)])
+            self.visit(value)
+        self.write(')')
+
+    def visit_Compare(self, node):
+        self.write('(')
+        self.write(node.left)
+        for op, right in zip(node.ops, node.comparators):
+            self.write(' %s %%' % CMPOP_SYMBOLS[type(op)])
+            self.visit(right)
+        self.write(')')
+
+    def visit_UnaryOp(self, node):
+        self.write('(')
+        op = UNARYOP_SYMBOLS[type(node.op)]
+        self.write(op)
+        if op == 'not':
+            self.write(' ')
+        self.visit(node.operand)
+        self.write(')')
+
+    def visit_Subscript(self, node):
+        self.visit(node.value)
+        self.write('[')
+        self.visit(node.slice)
+        self.write(']')
+
+    def visit_Slice(self, node):
+        if node.lower is not None:
+            self.visit(node.lower)
+        self.write(':')
+        if node.upper is not None:
+            self.visit(node.upper)
+        if node.step is not None:
+            self.write(':')
+            if not (isinstance(node.step, Name) and node.step.id == 'None'):
+                self.visit(node.step)
+
+    def visit_ExtSlice(self, node):
+        for idx, item in node.dims:
+            if idx:
+                self.write(', ')
+            self.visit(item)
+
+    def visit_Yield(self, node):
+        self.write('yield ')
+        self.visit(node.value)
+
+    def visit_Lambda(self, node):
+        self.write('lambda ')
+        self.signature(node.args)
+        self.write(': ')
+        self.visit(node.body)
+
+    def visit_Ellipsis(self, node):
+        self.write('Ellipsis')
+
+    def generator_visit(left, right):
+        def visit(self, node):
+            self.write(left)
+            self.visit(node.elt)
+            for comprehension in node.generators:
+                self.visit(comprehension)
+            self.write(right)
+        return visit
+
+    visit_ListComp = generator_visit('[', ']')
+    visit_GeneratorExp = generator_visit('(', ')')
+    visit_SetComp = generator_visit('{', '}')
+    del generator_visit
+
+    def visit_DictComp(self, node):
+        self.write('{')
+        self.visit(node.key)
+        self.write(': ')
+        self.visit(node.value)
+        for comprehension in node.generators:
+            self.visit(comprehension)
+        self.write('}')
+
+    def visit_IfExp(self, node):
+        self.visit(node.body)
+        self.write(' if ')
+        self.visit(node.test)
+        self.write(' else ')
+        self.visit(node.orelse)
+
+    def visit_Starred(self, node):
+        self.write('*')
+        self.visit(node.value)
+
+    def visit_Repr(self, node):
+        # XXX: python 2.6 only
+        self.write('`')
+        self.visit(node.value)
+        self.write('`')
+
+    # Helper Nodes
+
+    def visit_alias(self, node):
+        self.write(node.name)
+        if node.asname is not None:
+            self.write(' as ' + node.asname)
+
+    def visit_comprehension(self, node):
+        self.write(' for ')
+        self.visit(node.target)
+        self.write(' in ')
+        self.visit(node.iter)
+        if node.ifs:
+            for if_ in node.ifs:
+                self.write(' if ')
+                self.visit(if_)
+
+    def visit_excepthandler(self, node):
+        self.newline(node)
+        self.write('except')
+        if node.type is not None:
+            self.write(' ')
+            self.visit(node.type)
+            if node.name is not None:
+                self.write(' as ')
+                self.visit(node.name)
+        self.write(':')
+        self.body(node.body)