compiler/fold_constants: use eval_constant from tools

artiq/compiler/fold_constants.py

@@ -1,28 +1,6 @@
 import ast, operator
 
-from artiq.language import units
+from artiq.compiler.tools import *
-from artiq.compiler.tools import value_to_ast, make_stmt_transformer
-
-class _NotConstant(Exception):
-	pass
-
-def _get_constant(node):
-	if isinstance(node, ast.Num):
-		return node.n
-	elif isinstance(node, ast.Str):
-		return node.s
-	elif isinstance(node, ast.Call) \
-	  and isinstance(node.func, ast.Name) \
-	  and node.func.id == "Quantity":
-		amount, unit = node.args
-		amount = _get_constant(amount)
-		try:
-			unit = getattr(units, unit.id)
-		except:
-			raise _NotConstant
-		return units.Quantity(amount, unit)
-	else:
-		raise _NotConstant
 
 _ast_unops = {
 	ast.Invert: operator.inv,
@@ -50,8 +28,8 @@ class _ConstantFolder(ast.NodeTransformer):
 	def visit_UnaryOp(self, node):
 		self.generic_visit(node)
 		try:
-			operand = _get_constant(node.operand)
+			operand = eval_constant(node.operand)
-		except _NotConstant:
+		except NotConstant:
 			return node
 		try:
 			op = _ast_unops[type(node.op)]
@@ -66,8 +44,8 @@ class _ConstantFolder(ast.NodeTransformer):
 	def visit_BinOp(self, node):
 		self.generic_visit(node)
 		try:
-			left, right = _get_constant(node.left), _get_constant(node.right)
+			left, right = eval_constant(node.left), eval_constant(node.right)
-		except _NotConstant:
+		except NotConstant:
 			return node
 		try:
 			op = _ast_binops[type(node.op)]