basic ast

repl.py

@@ -2,7 +2,9 @@ import wasp.parser as parser
 
 line = raw_input(">> ")
 while line != "":
-    tree = parser.parse(line)
+    ptree = parser.parse(line)
-    print "^^", tree
+    print " ^ %s" % ptree
+    ast = ptree.ast()
+    print " ‡ %r" % ast
     #tree.eval()
     line = raw_input(">> ")

wasp/ast.py

@@ -0,0 +1,52 @@
+class Node(object):
+    pass
+
+
+class List(Node):
+    def __init__(self, car, cdr=None):
+        self.car = car
+        self.cdr = cdr
+
+    def eval(self):
+        pass
+
+    def __repr__(self):
+        return "<List %r %r>" % (self.car, self.cdr)
+
+
+class Atom(Node):
+    pass
+
+
+class Operator(Node):
+    pass
+
+
+class Number(Atom):
+    def __init__(self, value):
+        self.value = value
+
+    def eval(self):
+        return self.value
+
+    def __repr__(self):
+        return "<Number %s>" % self.value
+
+
+class Symbol(Atom):
+    pass
+
+
+class Quote(Node):
+    def __init__(self, sexpr):
+        self.sexpr = sexpr
+
+    def eval(self):
+        return self.sexpr.eval()
+
+    def __repr__(self):
+        return "<Quote %r>" % self.sexpr
+
+
+class Lambda(Node):
+    pass

wasp/parser/box.py

@@ -1,4 +1,5 @@
 from rply.token import BaseBox
+from wasp import ast
 
 
 class Quote(BaseBox):
@@ -11,6 +12,9 @@ class Quote(BaseBox):
     def __str__(self):
         return "'%s" % self.sexpr
 
+    def ast(self):
+        return ast.Quote(self.sexpr.ast())
+
 
 class Pair(BaseBox):
     def __init__(self, x, y=None):
@@ -24,6 +28,24 @@ class Pair(BaseBox):
             y = self.y
         return "(%s . %s)" % (self.x, y)
 
+    def r_cdr(self, cdr):
+        if self.y is None:
+            return (self.x.ast(), )
+        else:
+            return cdr + (self.x.ast(), ) + self.y.r_cdr(cdr)
+
+    def ast(self):
+        car = self.x.ast()
+
+        if self.y is None:
+            cdr = None
+        elif type(self.y) is Pair:
+            cdr = list(self.y.r_cdr(()))
+        else:
+            cdr = self.y.ast()
+
+        return ast.List(car, cdr)
+
 
 class Atom(BaseBox):
     def __init__(self, atom):
@@ -34,3 +56,6 @@ class Atom(BaseBox):
 
     def __str__(self):
         return "%s" % (self.atom)
+
+    def ast(self):
+        return ast.Number(int(self.atom))