Implemented short-circuit coalesce/ternary

EvaluableExpression.go

@@ -6,6 +6,7 @@ import (
 )
 
 const isoDateFormat string = "2006-01-02T15:04:05.999999999Z0700"
+const shortCircuitHolder int = -1
 
 var DUMMY_PARAMETERS = MapParameters(map[string]interface{}{})
 
@@ -162,7 +163,6 @@ func (this EvaluableExpression) evaluateStage(stage *evaluationStage, parameters
 
 	var left, right interface{}
 	var err error
-	var shortResult bool
 
 	if stage.leftStage != nil {
 		left, err = this.evaluateStage(stage.leftStage, parameters)
@@ -171,23 +171,33 @@ func (this EvaluableExpression) evaluateStage(stage *evaluationStage, parameters
 		}
 	}
 
-	if stage.isShortCircuitable() && isBool(left) {
-
-		shortResult = left.(bool)
-
+	if stage.isShortCircuitable() {
 		switch stage.symbol {
 			case AND:
-				if !shortResult {
+				if left == false {
 					return false, nil
 				}
 			case OR:
-				if shortResult {
+				if left == true {
 					return true, nil
 				}
+			case COALESCE:
+				if left != nil {
+					return left, nil
+				}
+
+			case TERNARY_TRUE:
+				if left == false {
+					right = shortCircuitHolder
+				}
+			case TERNARY_FALSE:
+				if left != nil {
+					right = shortCircuitHolder
+				}
 		}
 	}
 
-	if stage.rightStage != nil {
+	if right != shortCircuitHolder && stage.rightStage != nil {
 		right, err = this.evaluateStage(stage.rightStage, parameters)
 		if err != nil {
 			return nil, err

evaluation_test.go

@@ -1250,6 +1250,28 @@ func TestParameterizedEvaluation(test *testing.T) {
 			},
 			Expected: false,
 		},
+		EvaluationTest{
+
+			Name:  "Short-circuit ternary",
+			Input: "true ? 1 : fail()",
+			Functions: map[string]ExpressionFunction{
+				"fail": func(arguments ...interface{}) (interface{}, error) {
+					return nil, errors.New("Did not short-circuit")
+				},
+			},
+			Expected: 1.0,
+		},
+		EvaluationTest{
+
+			Name:  "Short-circuit coalesce",
+			Input: "'foo' ?? fail()",
+			Functions: map[string]ExpressionFunction{
+				"fail": func(arguments ...interface{}) (interface{}, error) {
+					return nil, errors.New("Did not short-circuit")
+				},
+			},
+			Expected: "foo",
+		},
 	}
 
 	runEvaluationTests(evaluationTests, test)