Added string concatenation

docs/TODO.txt

@@ -10,8 +10,8 @@ DONE: while-then
 DONE: for-then
 DONE: break and continue statements
 DONE: truthiness rethink
+DONE: string concat with the + operator
 
-TODO: string concat with the + operator
 TODO: increment & decrement operators
 TODO: a = b = c = 1;
 TODO: are compounds shallow or deep copies?

docs/spec.md

@@ -357,7 +357,7 @@ export hello as world;
 
 ## String
 
-Strings are a series of characters, and are created by surrounding said characters with a pair of double quotation marks `"`. Strings cannot exceed 4096 bytes in length.
+Strings are a series of characters, and are created by surrounding said characters with a pair of double quotation marks `"`. Strings cannot exceed 4096 bytes in length (this amount can be tweaked in the source).
 
 ```
 var greeting: string = "Hello world";

source/interpreter.c

@@ -230,6 +230,22 @@ static bool execArithmetic(Interpreter* interpreter, Opcode opcode) {
 	parseIdentifierToValue(interpreter, &rhs);
 	parseIdentifierToValue(interpreter, &lhs);
 
+	//special case for string concatenation ONLY
+	if (IS_STRING(lhs) && IS_STRING(rhs)) {
+		//check for overflow
+		if (STRLEN(lhs) + STRLEN(rhs) > MAX_STRING_LENGTH) {
+			printf("Can't concatenate these strings (result is too long)\n");
+			return false;
+		}
+
+		//concat the strings
+		char buffer[MAX_STRING_LENGTH];
+		snprintf(buffer, MAX_STRING_LENGTH, "%s%s", AS_STRING(lhs), AS_STRING(rhs));
+		pushLiteralArray(&interpreter->stack, TO_STRING_LITERAL(buffer));
+
+		return true;
+	}
+
 	//type coersion
 	if (IS_FLOAT(lhs) && IS_INTEGER(rhs)) {
 		rhs = TO_FLOAT_LITERAL(AS_INTEGER(rhs));

source/literal.c

@@ -81,12 +81,12 @@ void printLiteralCustom(Literal literal, void (printFn)(const char*)) {
 		break;
 
 		case LITERAL_STRING: {
-			char buffer[4096];
+			char buffer[MAX_STRING_LENGTH];
 			if (!quotes) {
-				snprintf(buffer, 4096, "%.*s", STRLEN(literal), AS_STRING(literal));
+				snprintf(buffer, MAX_STRING_LENGTH, "%.*s", STRLEN(literal), AS_STRING(literal));
 			}
 			else {
-				snprintf(buffer, 4096, "%c%.*s%c", quotes, STRLEN(literal), AS_STRING(literal), quotes);
+				snprintf(buffer, MAX_STRING_LENGTH, "%c%.*s%c", quotes, STRLEN(literal), AS_STRING(literal), quotes);
 			}
 			printFn(buffer);
 		}

source/literal.h

@@ -92,6 +92,7 @@ void freeLiteral(Literal literal);
 
 #define IS_TRUTHY(x) _isTruthy(x)
 
+#define MAX_STRING_LENGTH					4096
 #define STRLEN(lit)							((lit).as.string.length)
 #define STRLEN_I(lit)						((lit).as.identifier.length)
 #define HASH_I(lit)							((lit).as.identifier.hash)

source/parser.c

@@ -241,9 +241,11 @@ static Opcode string(Parser* parser, Node** nodeHandle) {
 			int length = parser->previous.length;
 
 			//for safety
-			if (length > 4096) {
+			if (length > MAX_STRING_LENGTH) {
-				length = 4096;
+				length = MAX_STRING_LENGTH;
-				error(parser, parser->previous, "Strings can only be a maximum of 4096 characters long");
+				char buffer[256];
+				snprintf(buffer, 256, "Strings can only be a maximum of %d characters long", MAX_STRING_LENGTH);
+				error(parser, parser->previous, buffer);
 			}
 
 			emitNodeLiteral(nodeHandle, TO_STRING_LITERAL(copyString(parser->previous.lexeme, length)));