1 files changed, 157 insertions, 0 deletions
diff --git a/sketch.py b/sketch.py
new file mode 100644
index 0000000..edd866c
--- /dev/null
+++ b/sketch.py
@@ -0,0 +1,157 @@
+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__()