umx_compiler

commit b9ce320fafd72790fdc6a5d95b92f6f3587edb96
parent c887ec01da2d32fb90c22dd84fe104ce5d6fa624
Author: bsandro <email@bsandro.tech>
Date:   Mon, 27 Jun 2022 00:12:30 +0300

string concat support

Diffstat:
M
eval/eval.go
 | 
11
+++++++++++
M
eval/eval_test.go
 | 
13
+++++++++++++

2 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/eval/eval.go b/eval/eval.go
@@ -142,6 +142,8 @@ func evalInfixExpression(operator string, left, right object.Object, ctx *object
 	switch {
 	case left.Type() == object.INTEGER_OBJ && right.Type() == object.INTEGER_OBJ:
 		return evalIntegerInfixExpression(operator, left, right, ctx)
+	case left.Type() == object.STRING_OBJ && right.Type() == object.STRING_OBJ:
+		return evalStringInfixExpression(operator, left, right, ctx)
 	case operator == "==":
 		return boolToObject(left == right)
 	case operator == "!=":
@@ -276,3 +278,12 @@ func unwrapReturnValue(obj object.Object) object.Object {
 	}
 	return obj
 }
+
+func evalStringInfixExpression(operator string, left, right object.Object, ctx *object.Context) object.Object {
+	if operator != "+" {
+		return newError("unknown operator: %s %s %s", left.Type(), operator, right.Type())
+	}
+	leftVal := left.(*object.String).Value
+	rightVal := right.(*object.String).Value
+	return &object.String{Value: leftVal + rightVal}
+}
diff --git a/eval/eval_test.go b/eval/eval_test.go
@@ -164,6 +164,7 @@ func TestErrorHandling(t *testing.T) {
 		{"true+false;", "unknown operator: BOOLEAN + BOOLEAN"},
 		{"if (10>1) { true + false; }", "unknown operator: BOOLEAN + BOOLEAN"},
 		{"foo", "identifier not found: foo"},
+		{`"foo"-"bar"`, "unknown operator: STRING - STRING"},
 	}
 	for _, tt := range tests {
 		evaluated := testEval(tt.input)
@@ -240,3 +241,15 @@ func TestStringLiteral(t *testing.T) {
 		t.Errorf("String has wrong value: %s", str.Value)
 	}
 }
+
+func TestStringsConcat(t *testing.T) {
+	input := `"hello" + " " + "world"`
+	evaluated := testEval(input)
+	str, ok := evaluated.(*object.String)
+	if !ok {
+		t.Fatalf("object is not a string")
+	}
+	if str.Value != "hello world" {
+		t.Fatalf("string value is wrong: %s", str.Value)
+	}
+}