Add `##` and `##=` operators

4 files changed, 54 insertions, 2 deletions

diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 91d9e669f..72de88f61 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -1995,6 +1995,12 @@ gb_internal bool check_binary_op(CheckerContext *c, Operand *o, Token op) {
 			return false;
 		}
 		break;
+	case Token_Concat:
+	case Token_ConcatEq:
+		if (!is_type_integer(type)) {
+			error(op, "Operator '%.*s' is only allowed with integer expressions", LIT(op.string));
+		}
+		break;
 
 	case Token_Add:
 		if (is_type_string(type)) {
diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index 0c82180ec..29c690096 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -1427,6 +1427,38 @@ handle_op:;
 			return res;
 		}
 		break;
+
+
+	case Token_Concat:
+		{
+			lbValue left  = lb_emit_conv(p, lhs, type);
+			lbValue right = lb_emit_conv(p, rhs, type);
+
+			lbValue ten = lb_const_int(p->module, type, 10);
+			lbAddr pow = lb_add_local_generated(p, type, false);
+			lb_addr_store(p, pow, ten);
+
+			lbBlock *loop = lb_create_block(p, "concat.loop");
+			lbBlock *body = lb_create_block(p, "concat.body");
+			lbBlock *done = lb_create_block(p, "concat.done");
+
+			lb_emit_jump(p, loop);
+			lb_start_block(p, loop);
+
+			lbValue cond = lb_emit_comp(p, Token_GtEq, right, lb_addr_load(p, pow));
+
+			lb_emit_if(p, cond, body, done);
+			lb_start_block(p, body);
+
+			lbValue pow_10 = lb_emit_arith(p, Token_Mul, lb_addr_load(p, pow), ten, type);
+			lb_addr_store(p, pow, pow_10);
+
+			lb_emit_jump(p, loop);
+			lb_start_block(p, done);
+
+			lbValue x = lb_emit_arith(p, Token_Mul, left, lb_addr_load(p, pow), type);
+			return lb_emit_arith(p, Token_Add, x, right, type);
+		}
 	}
 
 	GB_PANIC("unhandled operator of lb_emit_arith");
@@ -1517,7 +1549,9 @@ gb_internal lbValue lb_build_binary_expr(lbProcedure *p, Ast *expr) {
 	case Token_And:
 	case Token_Or:
 	case Token_Xor:
-	case Token_AndNot: {
+	case Token_AndNot:
+	case Token_Concat:
+	case Token_ConcatEq: {
 		Type *type = default_type(tv.type);
 		lbValue left = lb_build_expr(p, be->left);
 		lbValue right = lb_build_expr(p, be->right);
@@ -1604,6 +1638,7 @@ gb_internal lbValue lb_build_binary_expr(lbProcedure *p, Ast *expr) {
 			lbValue right = lb_build_expr(p, be->right);
 			return lb_build_binary_in(p, left, right, be->op.kind);
 		}
+
 	default:
 		GB_PANIC("Invalid binary expression");
 		break;
diff --git a/src/parser.cpp b/src/parser.cpp
index f38f79607..a38351220 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -3490,6 +3490,7 @@ gb_internal i32 token_precedence(AstFile *f, TokenKind t) {
 	case Token_AndNot:
 	case Token_Shl:
 	case Token_Shr:
+	case Token_Concat:
 		return 7;
 	}
 	return 0;
@@ -3778,6 +3779,7 @@ gb_internal Ast *parse_simple_stmt(AstFile *f, u32 flags) {
 	case Token_AndNotEq:
 	case Token_CmpAndEq:
 	case Token_CmpOrEq:
+	case Token_ConcatEq:
 	{
 		if (f->curr_proc == nullptr) {
 			syntax_error(f->curr_token, "You cannot use a simple statement in the file scope");
diff --git a/src/tokenizer.cpp b/src/tokenizer.cpp
index 53f6135d0..3a5828a3a 100644
--- a/src/tokenizer.cpp
+++ b/src/tokenizer.cpp
@@ -33,6 +33,7 @@ TOKEN_KIND(Token__OperatorBegin, ""), \
 	TOKEN_KIND(Token_AndNot,   "&~"), \
 	TOKEN_KIND(Token_Shl,      "<<"), \
 	TOKEN_KIND(Token_Shr,      ">>"), \
+	TOKEN_KIND(Token_Concat,   "##"), \
 	TOKEN_KIND(Token_CmpAnd,   "&&"), \
 	TOKEN_KIND(Token_CmpOr,    "||"), \
 \
@@ -49,6 +50,7 @@ TOKEN_KIND(Token__AssignOpBegin, ""), \
 	TOKEN_KIND(Token_AndNotEq, "&~="), \
 	TOKEN_KIND(Token_ShlEq,    "<<="), \
 	TOKEN_KIND(Token_ShrEq,    ">>="), \
+	TOKEN_KIND(Token_ConcatEq, "##="), \
 	TOKEN_KIND(Token_CmpAndEq, "&&="), \
 	TOKEN_KIND(Token_CmpOrEq,  "||="), \
 TOKEN_KIND(Token__AssignOpEnd, ""), \
@@ -937,7 +939,14 @@ gb_internal void tokenizer_get_token(Tokenizer *t, Token *token, int repeat=0) {
 			break;
 		case '#':
 			token->kind = Token_Hash;
-			if (t->curr_rune == '!') {
+			if (t->curr_rune == '#') {
+				advance_to_next_rune(t);
+				token->kind = Token_Concat;
+				if (t->curr_rune == '=') {
+					advance_to_next_rune(t);
+					token->kind = Token_ConcatEq;
+				}
+			} else if (t->curr_rune == '!') {
 				token->kind = Token_Comment;
 				tokenizer_skip_line(t);
 			} else if (t->curr_rune == '+') {