1 files changed, 76 insertions, 15 deletions

diff --git a/src/lower.c b/src/lower.c
index df095e4..141453c 100644
--- a/src/lower.c
+++ b/src/lower.c
@@ -34,7 +34,7 @@ static void indent(struct state *state)
 static int lower_var(struct ast *expr);
 
 static int lower_expr(struct state *state, struct ast *expr);
-static int lower_block(struct state *state, struct ast *block);
+static int lower_block(struct state *state, struct ast *block, bool ret);
 static int lower_closure(struct state *state, struct ast *closure);
 static int lower_statement(struct state *state, struct ast *stmt);
 
@@ -287,8 +287,18 @@ static int lower_moves(struct state *state, struct ast *moves)
 	return 0;
 }
 
+static int lower_err_branch(struct state *state, struct ast *err)
+{
+	return lower_block(state, err_branch_body(err), false);
+}
+
 static int lower_call(struct state *state, struct ast *call)
 {
+	struct ast *err = call_err(call);
+	/** @todo better default error name? */
+	const char *err_str = err ? err_branch_id(err) : "_fwd_err";
+
+	printf("if (auto %s = ", err_str);
 	if (lower_expr(state, call_expr(call)))
 		return -1;
 
@@ -297,7 +307,19 @@ static int lower_call(struct state *state, struct ast *call)
 	if (lower_moves(state, call_args(call)))
 		return -1;
 
-	printf(");\n");
+	printf("))");
+
+	if (!err) {
+		printf("\n");
+		indent(state);
+		printf(" return %s;\n", err_str);
+		return 0;
+	}
+
+	if (lower_err_branch(state, call_err(call)))
+		return -1;
+
+	printf("\n");
 	return 0;
 }
 
@@ -323,7 +345,7 @@ static int lower_if(struct state *state, struct ast *stmt)
 
 	printf(") ");
 
-	if (lower_block(state, if_body(stmt)))
+	if (lower_block(state, if_body(stmt), false))
 		return -1;
 
 	if (!if_else(stmt)) {
@@ -332,16 +354,36 @@ static int lower_if(struct state *state, struct ast *stmt)
 	}
 
 	printf(" else ");
-	if (lower_block(state, if_else(stmt)))
+	if (lower_block(state, if_else(stmt), false))
 		return -1;
 
 	printf("\n");
 	return 0;
 }
 
+static int lower_error(struct ast *err)
+{
+	assert(error_str(err) || error_id(err));
+	if (error_str(err)) {
+		printf("return %s;\n", error_str(err));
+		return 0;
+	}
+
+	struct ast *id = error_id(err);
+	printf("return %s;\n", id_str(id));
+	return 0;
+}
+
+static int lower_own(struct state *state, struct ast *stmt)
+{
+	printf("/* TODO own */\n");
+	return 0;
+}
+
 static int lower_statement(struct state *state, struct ast *stmt)
 {
 	switch (stmt->k) {
+	case AST_OWN:   return lower_own(state, stmt);
 	case AST_LET:   return lower_let(state, stmt);
 	case AST_CALL:  return lower_call(state, stmt);
 	case AST_IF:    return lower_if(state, stmt);
@@ -354,7 +396,7 @@ static int lower_statement(struct state *state, struct ast *stmt)
 	return 0;
 }
 
-static int lower_block(struct state *state, struct ast *block)
+static int lower_block(struct state *state, struct ast *block, bool ret)
 {
 	printf("{\n");
 	increase_indent(state);
@@ -366,8 +408,18 @@ static int lower_block(struct state *state, struct ast *block)
 			return -1;
 	}
 
-	decrease_indent(state);
+	if (block_error(block)) {
+		indent(state);
+		if (lower_error(block_error(block)))
+			return -1;
+	}
+
+	if (ret) {
+		indent(state);
+		printf("return nullptr;\n");
+	}
 
+	decrease_indent(state);
 	indent(state);
 	printf("}");
 	return 0;
@@ -407,7 +459,7 @@ static int lower_closure(struct state *state, struct ast *closure)
 
 	printf(")");
 
-	if (lower_block(state, closure_body(closure)))
+	if (lower_block(state, closure_body(closure), true))
 		return -1;
 
 	return 0;
@@ -420,12 +472,12 @@ static int lower_proto(struct ast *proc)
 	if (!proc_body(proc))
 		return 0;
 
+	printf("fwd_err_t ");
 	if (strcmp("main", proc_id(proc)) == 0)
-		printf("int ");
+		printf("fwd_main(");
 	else
-		printf("void ");
+		printf("%s(", proc_id(proc));
 
-	printf("%s(", proc_id(proc));
 
 	if (lower_vars(proc_params(proc)))
 		return -1;
@@ -439,12 +491,11 @@ static int lower_proc(struct ast *proc)
 	if (!proc_body(proc))
 		return 0;
 
+	printf("fwd_err_t ");
 	if (strcmp("main", proc_id(proc)) == 0)
-		printf("int ");
+		printf("fwd_main(");
 	else
-		printf("void ");
-
-	printf("%s(", proc_id(proc));
+		printf("%s(", proc_id(proc));
 
 	if (lower_vars(proc_params(proc)))
 		return -1;
@@ -452,7 +503,7 @@ static int lower_proc(struct ast *proc)
 	printf(")\n");
 
 	struct state state = {0};
-	if (lower_block(&state, proc_body(proc)))
+	if (lower_block(&state, proc_body(proc), true))
 		return -1;
 
 	printf("\n\n");
@@ -476,5 +527,15 @@ int lower(struct scope *root)
 			return -1;
 	}
 
+
+	puts("int main()");
+	puts("{");
+	puts("	fwd_err_t err = fwd_main();");
+	puts("	if (err) {");
+	puts("		fprintf(stderr, \"%s\", err);");
+	puts("		return -1;");
+	puts("	}");
+	puts("}");
+
 	return 0;
 }