Initial commit

ast.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+import nodes
+
+class AST(object):
+    def __init__(self, code):
+        self.nodes = []
+        while code != "":
+            code = self.add_node(code)
+        print self.nodes
+
+    def add_node(self, code):
+        for name in nodes.nodes:
+            node = nodes.nodes[name]
+            new_code, new_node = node.accepts(code)
+            if new_code is not None:
+                assert(new_node is not None)
+                self.nodes.append(new_node)
+                return new_code
+        raise SyntaxError("No nodes will accept code: %s"%(code))

main.py

@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+
+import ast
+import nodes
+
+ast.AST('p123p"')

nodes.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python
+
+nodes = {}
+
+class MetaNode(type):
+    def __new__(cls, name, bases, attrs):
+        new = super(MetaNode, cls).__new__(cls, name, bases, attrs)
+        if bases[0] is not object:
+            nodes[name] = new
+        return new
+
+class Node(object):
+    __metaclass__ = MetaNode
+    char = ""
+    func = lambda: None
+    args = 0
+    results = 0
+
+    def __init__(self):
+        print self
+
+    def __repr__(self):
+        return self.__class__.__name__
+
+    def __call__(self, *args):
+        assert(len(args) == self.args)
+        ret = func(*args)
+        assert(len(ret) == self.results)
+        return ret
+
+    @classmethod
+    def accepts(cls, code):
+        if code[0] == cls.char:
+            return code[1:], cls()
+        return None, None
+
+class PrintFunc(Node):
+    char = "p"
+    args = 1
+    results = 1
+    def func(arg):
+        print arg
+        return arg
+
+class NumericLiteral(Node):
+    args = 0
+    results = 1
+
+    def __init__(self, digits):
+        self.func = lambda: digits
+
+    def __repr__(self):
+        return "%s: %d"%(self.__class__.__name__, self.func())
+
+    @classmethod
+    def accepts(cls, code):
+        digits = ""
+        while code[0].isdigit():
+            digits += code[0]
+            code = code[1:]
+        if digits:
+            return code, cls(int(digits))
+        return None, None
+
+class StringLiteral(Node):
+    args = 0
+    results = 1
+
+    def __init__(self, string):
+        self.func = lambda: string
+
+    def __repr__(self):
+        return "%s: %r"%(self.__class__.__name__, self.func())
+
+    @classmethod
+    def accepts(cls, code):
+        string = None
+        if code[0] == '"':
+            string = ""
+            if len(code) != 1: 
+                code = code[1:]
+                while len(code) != 0 and code[0] != '"':
+                    string += code[0]
+                    code = code[1:]
+            if len(code) != 0: code = code[1:]
+        if string is not None:
+            return code, cls(string)
+        return None, None