umx_compiler

commit ed5362ca03dff4a3b9d7b3c0958a450b9a46db7d
parent d068fe3b1d66c3d0500299e2c3ae1388b4d0cf0a
Author: bsandro <email@bsandro.tech>
Date:   Fri, 24 Jun 2022 00:44:54 +0300

if-else eval

Diffstat:
M
eval/eval.go
 | 
28
++++++++++++++++++++++++++++
M
eval/eval_test.go
 | 
32
++++++++++++++++++++++++++++++++

2 files changed, 60 insertions(+), 0 deletions(-)
diff --git a/eval/eval.go b/eval/eval.go
@@ -36,6 +36,10 @@ func Eval(node ast.Node) object.Object {
 		left := Eval(node.Left)
 		right := Eval(node.Right)
 		return evalInfixExpression(node.Operator, left, right)
+	case *ast.BlockStatement:
+		return evalStatements(node.Statements)
+	case *ast.IfExpression:
+		return evalIfExpression(node)
 	}
 	return nil
 }
@@ -117,3 +121,27 @@ func evalIntegerInfixExpression(operator string, left, right object.Object) obje
 		return NULL
 	}
 }
+
+func evalIfExpression(ie *ast.IfExpression) object.Object {
+	condition := Eval(ie.Condition)
+	if isTruthy(condition) {
+		return Eval(ie.Consequence)
+	} else if ie.Alternative != nil {
+		return Eval(ie.Alternative)
+	} else {
+		return NULL
+	}
+}
+
+func isTruthy(obj object.Object) bool {
+	switch obj {
+	case NULL:
+		return false
+	case TRUE:
+		return true
+	case FALSE:
+		return false
+	default:
+		return true
+	}
+}
diff --git a/eval/eval_test.go b/eval/eval_test.go
@@ -99,3 +99,35 @@ func TestShriekOperator(t *testing.T) {
 		testBooleanObject(t, evaluated, tt.expected)
 	}
 }
+
+func TestIfElseExpressions(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected interface{}
+	}{
+		{"if (true) { 10 }", 10},
+		{"if (false) { 20 }", nil},
+		{"if (1) { 30 }", 30},
+		{"if (1<2) { 40 }", 40},
+		{"if (1>2) { 11 }", nil},
+		{"if (1>2) { 50 } else { 60 }", 60},
+		{"if (1<2) { 50 } else { 60 }", 50},
+	}
+	for _, tt := range tests {
+		evaluated := testEval(tt.input)
+		integer, ok := tt.expected.(int)
+		if ok {
+			testIntegerObject(t, evaluated, int64(integer))
+		} else {
+			testNullObject(t, evaluated)
+		}
+	}
+}
+
+func testNullObject(t *testing.T, obj object.Object) bool {
+	if obj != NULL {
+		t.Errorf("obj is not NULL but %T (%+v)", obj, obj)
+		return false
+	}
+	return true
+}