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class SyntaxObj(object):
pass
class EvalObj(SyntaxObj):
def __str__(self):
return "#<Object>"
class ValObj(EvalObj):
def __str__(self):
return "#<Value>"
class NumberObj(ValObj):
def __str__():
return "#<Number>"
class IntObj(NumberObj):
def __init__(self, num):
self.val = int(num)
def __str__():
return "#<Integer>"
class FloatObj(NumberObj):
def __init__(self, num):
self.val = float(num)
def __str__():
return "#<Float>"
class StringObj(ValObj):
def __init__(self, string):
self.val = string
def __str__():
return "#<String>"
class ProcObj(ValObj):
def __init__(self, env, prog):
self.val = proc
def __str__():
return "#<Procedure>"
class IdObj(SyntaxObj):
def __init__(self, string):
self.name = string
def get_name():
return self.name
class Tokenizor():
def __init__(self):
self.data = ""
self.tokenized = list()
self.extended_chars = "!$%&*+-./:<=>?@^_~"
def is_identifier(self, string):
if string[0].isdigit(): return False
for i in string[1:]:
if not (i.isalnum() or i in self.extended_chars):
return False
return True
def feed(self, data):
self.data = data
def read(self):
if len(self.tokenized) == 0:
if len(self.data) == 0:
return None
self.tokenized = self.data.replace('(', '( ')\
.replace(')', ' )')\
.split()
self.data = ""
return self.tokenized.pop(0)
class AST(EvalObj):
class Node(object):
def __init__(self, syn_obj, sib = None, chd = None):
self.obj = syn_obj
self.sib = sib
self.chd = chd
def __str__(self):
return \
"Obj: " + str(self.obj) + " " + \
"Sib: " + str(self.sib) + " " + \
"Chd: " + str(self.chd)
def to_node(self, obj):
if isinstance(obj, self.Node): return obj
# else the obj is a string
try: return self.Node(IntObj(obj))
except ValueError:
try: return self.Node(FloatObj(obj))
except ValueError: return self.Node(IdObj(obj))
def __init__(self, stream):
stack = list()
while True:
token = stream.read()
if token is None: break
if token == '(':
stack.append(token)
elif token == ')':
lst = list()
while stack[-1] != '(':
lst = stack[-1:] + lst
del stack[-1]
root = self.to_node(lst[0])
if len(lst) > 1:
root.chd = self.to_node(lst[1])
ref = root.chd
for i in lst[2:]:
ref.sib = self.to_node(i)
ref = ref.sib
stack[-1] = root
else:
stack.append(token)
self.tree = stack
class Environment(object):
def __init__(self):
self.binding = dict()
def add_entry(id_obj, eval_obj):
self.binding[id_obj] = eval_obj
def get_obj(id_obj):
return self.binding[id_obj]
class Continuation(object):
def __init__(self, envt, pc, old_cont):
self.envt = envt
self.pc = pc
self.old_cont = old_cont
def get_envt(self):
return self.envt
def get_cont(self):
return self.cont
class Evaluator(object):
def __init__(self):
self.envt = Environment()
self.cont = None
self.pc = None
def run(self, prog):
self.stack = list() # object stack
self.flag = list() # call flag True for call False for value
self.pc = prog # Set to the root
self.top = 0 # Stack top
while self.flag[0]: # Still need to evaluate
pass
t = Tokenizor()
t.feed("(lambda (x) (x * x))")
a = AST(t)
root = a.tree
print root.__str__()
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