Infix Operator Evaluation for Boolean Comparisons

2 files changed, 37 insertions, 5 deletions

diff --git a/evaluator/evaluator.go b/evaluator/evaluator.go
index 5d69e2b..479e244 100644
--- a/evaluator/evaluator.go
+++ b/evaluator/evaluator.go
@@ -7,7 +7,7 @@ import (
 
 var (
 	NULL  = &object.Null{}
-	TRUE = &object.Boolean{Value: true}
+	TRUE  = &object.Boolean{Value: true}
 	FALSE = &object.Boolean{Value: false}
 )
 
@@ -31,7 +31,7 @@ func Eval(node ast.Node) object.Object {
 	case *ast.PrefixExpression:
 		right := Eval(node.Right)
 		return evalPrefixExpression(node.Operator, right)
-	
+
 	case *ast.InfixExpression:
 		left := Eval(node.Left)
 		right := Eval(node.Right)
@@ -73,6 +73,10 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 	switch {
 	case left.Type() == object.INTEGER_OBJ && right.Type() == object.INTEGER_OBJ:
 		return evalIntegerInfixExpression(operator, left, right)
+	case operator == "==":
+		return nativeBoolToBooleanObject(left == right)
+	case operator == "!=":
+		return nativeBoolToBooleanObject(left != right)
 	default:
 		return NULL
 	}
@@ -112,7 +116,18 @@ func evalIntegerInfixExpression(operator string, left, right object.Object) obje
 	case "*":
 		return &object.Integer{Value: leftValue * rightValue}
 	case "/":
+		if rightValue == 0 {
+			return NULL
+		}
 		return &object.Integer{Value: leftValue / rightValue}
+	case "<":
+		return nativeBoolToBooleanObject(leftValue < rightValue)
+	case ">":
+		return nativeBoolToBooleanObject(leftValue > rightValue)
+	case "==":
+		return nativeBoolToBooleanObject(leftValue == rightValue)
+	case "!=":
+		return nativeBoolToBooleanObject(leftValue != rightValue)
 	default:
 		return NULL
 	}
diff --git a/evaluator/evaluator_test.go b/evaluator/evaluator_test.go
index f0a5180..e5bc66c 100644
--- a/evaluator/evaluator_test.go
+++ b/evaluator/evaluator_test.go
@@ -10,7 +10,7 @@ import (
 
 func TestEvalIntegerExpression(t *testing.T) {
 	tests := []struct {
-		input	string
+		input    string
 		expected int64
 	}{
 		{"5", 5},
@@ -38,11 +38,28 @@ func TestEvalIntegerExpression(t *testing.T) {
 
 func TestEvalBooleanExpression(t *testing.T) {
 	tests := []struct {
-		input	string
+		input    string
 		expected bool
 	}{
 		{"true", true},
 		{"false", false},
+		{"1 < 2", true},
+		{"1 > 2", false},
+		{"1 < 1", false},
+		{"1 > 1", false},
+		{"1 == 1", true},
+		{"1 != 1", false},
+		{"1 == 2", false},
+		{"1 != 2", true},
+		{"true == true", true},
+		{"false == false", true},
+		{"true == false", false},
+		{"true != false", true},
+		{"false != true", true},
+		{"(1 < 2) == true", true},
+		{"(1 < 2) == false", false},
+		{"(1 > 2) == true", false},
+		{"(1 > 2) == false", true},
 	}
 
 	for _, tt := range tests {
@@ -53,7 +70,7 @@ func TestEvalBooleanExpression(t *testing.T) {
 
 func TestBangOperator(t *testing.T) {
 	tests := []struct {
-		input string
+		input    string
 		expected bool
 	}{
 		{"!true", false},