Added string concat

"He" + "llo"
"He" + 77

Author: blitmaps

src/compiler.c

@@ -1011,15 +1011,19 @@ void term() {
 }
 
 void additive_expr() {
-    term();
+    term(); // Parses multiplication/division first
     while (curr.type == TK_PLUS || curr.type == TK_MINUS) {
         MyloTokenType op = curr.type;
         next_token();
         term();
         switch (op) {
-            case TK_PLUS: emit(OP_ADD);
+            case TK_PLUS:
+                // The VM's exec_math_op already checks if the
+                // operands are T_STR and performs concatenation.
+                emit(OP_ADD);
                 break;
-            case TK_MINUS: emit(OP_SUB);
+            case TK_MINUS:
+                emit(OP_SUB);
                 break;
             default: break;
         }
@@ -1166,11 +1170,8 @@ static void parse_region() {
 static void parse_print() {
     match(TK_PRINT);
     match(TK_LPAREN);
-    if (curr.type == TK_STR) {
-        int id = make_string(compiling_vm, curr.text);
-        emit(OP_PSH_STR); emit(id);
-        match(TK_STR);
-    } else expression();
+    expression();
+
     match(TK_RPAREN);
     emit(OP_PRN);
 }

src/vm.c

@@ -1089,6 +1089,27 @@ static void exec_math_op(VM* vm, int op) {
         broadcast_math(vm, op, arrVal, scalVal, scalType, objIsLhs);
         return;
     }
+
+    if (op == OP_ADD && (ta == T_STR || tb == T_STR)) {
+        char s1[MAX_STRING_LENGTH], s2[MAX_STRING_LENGTH];
+
+        // Convert Left Side
+        if (ta == T_STR) strncpy(s1, vm->string_pool[(int)a], MAX_STRING_LENGTH-1);
+        else snprintf(s1, MAX_STRING_LENGTH, "%g", a);
+        s1[MAX_STRING_LENGTH-1] = '\0';
+
+        // Convert Right Side
+        if (tb == T_STR) strncpy(s2, vm->string_pool[(int)b], MAX_STRING_LENGTH-1);
+        else snprintf(s2, MAX_STRING_LENGTH, "%g", b);
+        s2[MAX_STRING_LENGTH-1] = '\0';
+
+        char res[MAX_STRING_LENGTH * 2];
+        snprintf(res, sizeof(res), "%s%s", s1, s2);
+        int id = make_string(vm, res);
+        vm->stack[vm->sp] = (double)id;
+        vm->stack_types[vm->sp] = T_STR;
+        return;
+    }
     RUNTIME_ERROR("Invalid types for math operation");
 }
 

tests/test_generate_list.h

@@ -462,6 +462,19 @@ inline TestOutput test_list_concat() {
     return run_source_test(src, expected);
 }
 
+inline TestOutput test_string_concat() {
+
+    std::string src = """"
+    "print(\"He\" + \"llo\")\n"
+    "print(\"He\" + 77)\n";
+
+    std::string expected = """"
+    "Hello\nHe77\n";
+
+    return run_source_test(src, expected);
+}
+
+
 inline TestOutput test_list_slices() {
 
     std::string src = """"
@@ -1328,6 +1341,7 @@ inline void test_generate_list() {
     ADD_TEST("Test Struct", test_struct);
     ADD_TEST("Test Type Struct", test_typed_struct);
     ADD_TEST("Test String Interpolation", test_string_interp);
+    ADD_TEST("Test String Concat", test_string_concat);
     ADD_TEST("Test Scope", test_scope);
     ADD_TEST("Test Variable Access", test_var_access);
     ADD_TEST("Test Reverse Loop", test_literal_reverse);