eval: Remove _ExprEvaluator

Signed-off-by: Martin Povišer <povik@cutebit.org>

fold/eval.py

@@ -125,8 +125,32 @@ def __call__(self, expr):
                 raise ValueError("Unknown expression node of type %s" % type(expr))
 
 
-class _ExprEvaluator(ExprVisitor):
-    def on_Op_builtin(self, expr):
+def index(v, indices):
+    if len(indices) == 0:
+        return v
+    if isinstance(v, list):
+        return index(v[indices[0]], indices[1:])
+    if isinstance(v, int) and len(indices) == 1:
+        return bool((v >> indices[0]) & 1)
+    raise NotImplementedError
+
+
+class ConstExprEvaluator(ExprVisitor):
+    def __init__(self, constvals):
+        self.constvals = constvals
+
+    def on_Var(self, expr):
+        varname = expr.varname
+
+        if varname in self.constvals:
+            return self.constvals[varname]
+        else:
+            raise ast.BadInput("no such constant or variable: '%s'" % varname)
+
+    def on_Const(self, expr):
+        return expr.val
+
+    def on_Op(self, expr):
         opname = expr.opname
         args = [self(node) for node in expr.args]
 
@@ -173,77 +197,19 @@ def on_Op_builtin(self, expr):
             return int(args[0] != 0 and args[1] != 0)
         if opname == "?:":
             return args[1] if args[0] else args[2]
-
-        # these below need special treatment of zero case if we are
-        # working with python integers
-        if opname == "//":
-            return args[0]//args[1]
-        if opname == "%":
-            return args[0]%args[1]
-
-    def on_Op(self, expr):
-        val = self.on_Op_builtin(expr)
-        if val is not None:
-            return val
-
-        raise NotImplementedError("unimplemented: evaluation of %s" % expr)
-
-    def on_unimplemented(self, expr):
-        raise NotImplementedError
-
-    on_Var = on_unimplemented
-    on_Const = on_unimplemented
-    on_Special = on_unimplemented
-
-
-def index(v, indices):
-    if len(indices) == 0:
-        return v
-    if isinstance(v, list):
-        return index(v[indices[0]], indices[1:])
-    if isinstance(v, int) and len(indices) == 1:
-        return bool((v >> indices[0]) & 1)
-    raise NotImplementedError
-
-
-class ConstExprEvaluator(_ExprEvaluator):
-    def __init__(self, constvals):
-        self.constvals = constvals
-
-    def on_Var(self, expr):
-        varname = expr.varname
-
-        if varname in self.constvals:
-            return self.constvals[varname]
-        else:
-            raise ast.BadInput("no such constant or variable: '%s'" % varname)
-
-    def on_Const(self, expr):
-        return expr.val
-
-    def on_Op(self, expr):
-        opname, args = expr.opname, expr.args
-
         if opname == "log2ceil":
-            return (self(args[0])-1).bit_length()
-
+            return (args[0]-1).bit_length()
         if opname == "ctz":
-            v = self(args[0])
+            v = args[0]
             return (v & -v).bit_length() - 1
-
-        if opname not in ast.Expr.SPECIAL_OPNAMES:
-            raise ast.BadInput("function calls are unsupported in constant expressions")
-
         if opname == "[":
-            return index(self(args[0]), [self(n) for n in args[1:]])
+            return index(args[0], args[1:])
         if opname == "//":
-            args = [self(a) for a in args]
             return (args[0]//args[1]) if args[1] != 0 else 0
         if opname == "%":
-            args = [self(a) for a in args]
             return (args[0]%args[1]) if args[1] != 0 else 0
 
-        return super().on_Op(expr)
+        raise ast.BadInput("function calls are unsupported in constant expressions")
 
 
 if __name__ == "__main__":

fold/logic/eval.py

@@ -5,7 +5,7 @@
 import sys
 
 from .. import ast
-from ..eval import _ExprEvaluator
+from ..eval import ExprVisitor
 from ..utils import product
 
 from .shape import SignalValue, Shape
@@ -17,7 +17,7 @@
              "&&", "||", "%", "?:", "^"]
 
 
-class CombinatorialEvaluator(_ExprEvaluator):
+class CombinatorialEvaluator(ExprVisitor):
     def __init__(self, rtl_module):
         self.m = rtl_module
 

fold/machinecode/__init__.py

@@ -324,7 +324,7 @@ def wrapper(self, arg1, arg2, *operands, **kwargs):
 
 # TODO: check `common_shape` variables versus shape policies
 # does the result IR shape match up only by accident?
-class ExprEvaluator(baseeval._ExprEvaluator):
+class ExprEvaluator(baseeval.ExprVisitor):
     def __init__(self, frame):
         self.frame = frame