add constant compare

filter/eval.go

@@ -330,15 +330,37 @@ func (e *BinaryExpr) singleEval(data KVs) bool {
  case *NilLiteral:
  lit = rhs
 
+ case *BoolLiteral:
+ lit = rhs.Val
+
  default:
 
  log.Errorf("invalid RHS, got type `%s'", reflect.TypeOf(e.RHS).String())
  return false
  }
 
- // first: fetch left-handle-symbol and OP on right-handle-symbol
- lhs, ok := e.LHS.(*Identifier)
- if !ok {
+ var lhs *Identifier
+ switch left := e.LHS.(type) {
+ case *NilLiteral:
+ return binEval(e.Op, nilVal, lit)
+
+ case *NumberLiteral:
+ if left.IsInt {
+ return binEval(e.Op, left.Int, lit)
+ } else {
+ return binEval(e.Op, left.Float, lit)
+ }
+
+ case *BoolLiteral:
+ return binEval(e.Op, left.Val, lit)
+
+ case *StringLiteral:
+ return binEval(e.Op, left.Val, lit)
+
+ case *Identifier:
+ lhs = left // we get detailed lhs value later...
+
+ default:
  log.Errorf("unknown LHS type, expect Identifier, got `%s'", reflect.TypeOf(e.LHS).String())
  return false
  }

filter/eval_test.go

@@ -161,6 +161,35 @@ func TestExprConditions(t *testing.T) {
  in: "{ xyz != nil }",
  pass: false,
  },
+
+ {
+ in: "{ nil = nil }", // nil literal
+ pass: true,
+ },
+
+ {
+ in: "{ 1 = 1 }", // int literal
+ pass: true,
+ },
+
+ {
+ in: "{ true = true }", // boolean literal
+ pass: true,
+ },
+
+ {
+ in: "{ 'hello' = 'hello'}", // string literal
+ pass: true,
+ },
+
+ {
+ in: "{ 1.0 = 1.0 }", // float literal
+ pass: true,
+ },
+ {
+ in: "{ 'abc' = 'ABC' }",
+ pass: false,
+ },
  }
 
  for _, tc := range cases {