🐐 short circuit evaluation

centvrion/ast_nodes.py

@@ -806,6 +806,20 @@ class BinOp(Node):
     return f"({self.left.print()} {OP_STR[self.op]} {self.right.print()})"
 
   def _eval(self, vtable):
+    # Short-circuit for logical operators
+    if self.op == "KEYWORD_AVT":
+      vtable, left = self.left.eval(vtable)
+      if bool(left):
+        return vtable, ValBool(True)
+      vtable, right = self.right.eval(vtable)
+      return vtable, ValBool(bool(right))
+    if self.op == "KEYWORD_ET":
+      vtable, left = self.left.eval(vtable)
+      if not bool(left):
+        return vtable, ValBool(False)
+      vtable, right = self.right.eval(vtable)
+      return vtable, ValBool(bool(right))
+
     vtable, left = self.left.eval(vtable)
     vtable, right = self.right.eval(vtable)
     lv, rv = left.value(), right.value()
@@ -874,10 +888,6 @@ class BinOp(Node):
             (isinstance(left, ValNul) and isinstance(right, ValInt) and rv == 0)):
           return vtable, ValBool(False)
         return vtable, ValBool(lv != rv)
-      case "KEYWORD_ET":
-        return vtable, ValBool(bool(left) and bool(right))
-      case "KEYWORD_AVT":
-        return vtable, ValBool(bool(left) or bool(right))
       case _:
         raise Exception(self.op)
 

centvrion/compiler/emit_expr.py

@@ -93,6 +93,25 @@ def emit_expr(node, ctx):
     return [f'CentValue {tmp} = cent_scope_get(&_scope, "{node.name}");'], tmp
 
   if isinstance(node, BinOp):
+    # Short-circuit for logical operators
+    if node.op in ("KEYWORD_AVT", "KEYWORD_ET"):
+      l_lines, l_var = emit_expr(node.left, ctx)
+      r_lines, r_var = emit_expr(node.right, ctx)
+      tmp = ctx.fresh_tmp()
+      if node.op == "KEYWORD_AVT":
+        lines = l_lines + [f"CentValue {tmp};"]
+        lines += [f"if (cent_truthy({l_var})) {{ {tmp} = cent_bool(1); }} else {{"]
+        lines += [f"  {l}" for l in r_lines]
+        lines += [f"  {tmp} = cent_bool(cent_truthy({r_var}));"]
+        lines += ["}"]
+      else:
+        lines = l_lines + [f"CentValue {tmp};"]
+        lines += [f"if (!cent_truthy({l_var})) {{ {tmp} = cent_bool(0); }} else {{"]
+        lines += [f"  {l}" for l in r_lines]
+        lines += [f"  {tmp} = cent_bool(cent_truthy({r_var}));"]
+        lines += ["}"]
+      return lines, tmp
+
     l_lines, l_var = emit_expr(node.left, ctx)
     r_lines, r_var = emit_expr(node.right, ctx)
     tmp = ctx.fresh_tmp()

tests.py

@@ -698,6 +698,9 @@ error_tests = [
   ("DEFINI f () VT { REDI(I) }\nINVOCA f (I)", CentvrionError),        # args to zero-param function
   ("SI NVLLVS TVNC { DESIGNA r VT I }", CentvrionError),               # NVLLVS cannot be used as boolean
   ("NVLLVS AVT VERITAS", CentvrionError),                              # NVLLVS cannot be used as boolean in AVT
+  ("FALSITAS AVT NVLLVS", CentvrionError),                             # no short-circuit: right side evaluated, NVLLVS not boolean
+  ("VERITAS ET NVLLVS", CentvrionError),                               # no short-circuit: right side evaluated, NVLLVS not boolean
+  ("NVLLVS ET VERITAS", CentvrionError),                               # NVLLVS cannot be used as boolean in ET
   ('"hello" + " world"', CentvrionError),                              # use & for string concatenation, not +
   ("[I, II][III]", CentvrionError),                                    # index too high
   ("CVM SVBNVLLA\n[I, II][-I]", CentvrionError),                       # negative index
@@ -1612,6 +1615,32 @@ et_avt_tests = [
   ("SI FALSITAS AVT FALSITAS TVNC { DESIGNA r VT I } ALIVD { DESIGNA r VT II }\nr",
     Program([], [SiStatement(BinOp(Bool(False), Bool(False), "KEYWORD_AVT"), [Designa(ID("r"), Numeral("I"))], [Designa(ID("r"), Numeral("II"))]), ExpressionStatement(ID("r"))]),
     ValInt(2)),
+  # short-circuit: right side not evaluated when result is determined
+  ("VERITAS AVT NVLLVS",
+    Program([], [ExpressionStatement(BinOp(Bool(True), Nullus(), "KEYWORD_AVT"))]),
+    ValBool(True)),
+  ("FALSITAS ET NVLLVS",
+    Program([], [ExpressionStatement(BinOp(Bool(False), Nullus(), "KEYWORD_ET"))]),
+    ValBool(False)),
+  # short-circuit with side-effect-prone expressions
+  ("DESIGNA x VT NVLLVS\nSI x EST NVLLVS AVT [I, II][x] EST I TVNC { DESIGNA r VT I } ALIVD { DESIGNA r VT II }\nr",
+    Program([], [
+      Designa(ID("x"), Nullus()),
+      SiStatement(
+        BinOp(BinOp(ID("x"), Nullus(), "KEYWORD_EST"), BinOp(ArrayIndex(DataArray([Numeral("I"), Numeral("II")]), ID("x")), Numeral("I"), "KEYWORD_EST"), "KEYWORD_AVT"),
+        [Designa(ID("r"), Numeral("I"))],
+        [Designa(ID("r"), Numeral("II"))]),
+      ExpressionStatement(ID("r"))]),
+    ValInt(1)),
+  ("DESIGNA x VT NVLLVS\nSI x DISPAR NVLLVS ET [I, II][x] EST I TVNC { DESIGNA r VT I } ALIVD { DESIGNA r VT II }\nr",
+    Program([], [
+      Designa(ID("x"), Nullus()),
+      SiStatement(
+        BinOp(BinOp(ID("x"), Nullus(), "KEYWORD_DISPAR"), BinOp(ArrayIndex(DataArray([Numeral("I"), Numeral("II")]), ID("x")), Numeral("I"), "KEYWORD_EST"), "KEYWORD_ET"),
+        [Designa(ID("r"), Numeral("I"))],
+        [Designa(ID("r"), Numeral("II"))]),
+      ExpressionStatement(ID("r"))]),
+    ValInt(2)),
 ]
 
 class TestEtAvt(unittest.TestCase):