From 18758d87f69212a5f81f014114502b022f6064b8 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Tue, 6 Nov 2012 13:52:19 +0100
Subject: [PATCH] pytholite: do not use ast.NodeVisitor

---
 migen/pytholite/compiler.py | 114 ++++++++++++++++++++++++++++++------
 1 file changed, 97 insertions(+), 17 deletions(-)

diff --git a/migen/pytholite/compiler.py b/migen/pytholite/compiler.py
index 5a9e0978b..e3f5a7609 100644
--- a/migen/pytholite/compiler.py
+++ b/migen/pytholite/compiler.py
@@ -37,31 +37,76 @@ class _Register:
 		sync = [Case(self.sel, *cases)]
 		return Fragment(sync=sync)
 
-class _AnonymousRegister:
-	def __init__(self, nbits):
-		self.nbits = nbits
-
-class _CompileVisitor(ast.NodeVisitor):
+class _Compiler:
 	def __init__(self, symdict, registers):
 		self.symdict = symdict
 		self.registers = registers
+		self.targetname = ""
 	
-	def visit_Assign(self, node):
-		value = self.visit(node.value)
-		if isinstance(value, _AnonymousRegister):
-			if isinstance(node.targets[0], ast.Name):
-				name = node.targets[0].id
+	def visit_top(self, node):
+		if isinstance(node, ast.Module) \
+		  and len(node.body) == 1 \
+		  and isinstance(node.body[0], ast.FunctionDef):
+			return self.visit_block(node.body[0].body)
+		else:
+			raise NotImplementedError
+	
+	# blocks and statements
+	def visit_block(self, statements):
+		r = []
+		for statement in statements:
+			if isinstance(statement, ast.Assign):
+				r += self.visit_assign(statement)
 			else:
 				raise NotImplementedError
-			value = _Register(name, value.nbits)
+		return r
+	
+	def visit_assign(self, node):
+		if isinstance(node.targets[0], ast.Name):
+			self.targetname = node.targets[0].id
+		value = self.visit_expr(node.value, True)
+		self.targetname = ""
+		
+		if isinstance(value, _Register):
 			self.registers.append(value)
 			for target in node.targets:
 				if isinstance(target, ast.Name):
 					self.symdict[target.id] = value
 				else:
 					raise NotImplementedError
+			return []
+		elif isinstance(value, Value):
+			r = []
+			for target in node.targets:
+				if isinstance(target, ast.Attribute) and target.attr == "store":
+					treg = target.value
+					if isinstance(treg, ast.Name):
+						r.append(self.symdict[treg.id].load(value))
+					else:
+						raise NotImplementedError
+				else:
+					raise NotImplementedError
+			return r
+		else:
+			raise NotImplementedError
 	
-	def visit_Call(self, node):
+	# expressions
+	def visit_expr(self, node, allow_call=False):
+		if isinstance(node, ast.Call):
+			if allow_call:
+				return self.visit_expr_call(node)
+			else:
+				raise NotImplementedError
+		elif isinstance(node, ast.BinOp):
+			return self.visit_expr_binop(node)
+		elif isinstance(node, ast.Name):
+			return self.visit_expr_name(node)
+		elif isinstance(node, ast.Num):
+			return self.visit_expr_num(node)
+		else:
+			raise NotImplementedError
+	
+	def visit_expr_call(self, node):
 		if isinstance(node.func, ast.Name):
 			callee = self.symdict[node.func.id]
 		else:
@@ -70,19 +115,54 @@ class _CompileVisitor(ast.NodeVisitor):
 			if len(node.args) != 1:
 				raise TypeError("Register() takes exactly 1 argument")
 			nbits = ast.literal_eval(node.args[0])
-			return _AnonymousRegister(nbits)
+			return _Register(self.targetname, nbits)
 		else:
 			raise NotImplementedError
 	
+	def visit_expr_binop(self, node):
+		left = self.visit_expr(node.left)
+		right = self.visit_expr(node.right)
+		if isinstance(node.op, ast.Add):
+			return left + right
+		elif isinstance(node.op, ast.Sub):
+			return left - right
+		elif isinstance(node.op, ast.Mult):
+			return left * right
+		elif isinstance(node.op, ast.LShift):
+			return left << right
+		elif isinstance(node.op, ast.RShift):
+			return left >> right
+		elif isinstance(node.op, ast.BitOr):
+			return left | right
+		elif isinstance(node.op, ast.BitXor):
+			return left ^ right
+		elif isinstance(node.op, ast.BitAnd):
+			return left & right
+		else:
+			raise NotImplementedError
+	
+	def visit_expr_name(self, node):
+		r = self.symdict[node.id]
+		if isinstance(r, _Register):
+			r = r.storage
+		return r
+	
+	def visit_expr_num(self, node):
+		return node.n
+
 def make_pytholite(func):
 	tree = ast.parse(inspect.getsource(func))
 	symdict = func.__globals__.copy()
 	registers = []
 	
-	cv = _CompileVisitor(symdict, registers)
-	cv.visit(tree)
+	c = _Compiler(symdict, registers)
+	print("compilation result:")
+	print(c.visit_top(tree))
 	
+	print("registers:")
 	print(registers)
-	print(symdict)
+	#print("symdict:")
+	#print(symdict)
 
-	#print(ast.dump(tree))
+	print("ast:")
+	print(ast.dump(tree))