From 0cef986e6958a0a6a7e94e8256b0039709aed56b Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Fri, 6 Dec 2024 20:00:42 +0200
Subject: add trailing closures

+ Useful for guard statements, not entirely sure about the final syntax
  but at least they're possible
---
 src/lower.c  | 17 ++++++++++++++++-
 src/parser.y | 24 +++++++++++++++++++++---
 2 files changed, 37 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/lower.c b/src/lower.c
index 35d16fe..4b9fae9 100644
--- a/src/lower.c
+++ b/src/lower.c
@@ -123,6 +123,11 @@ static int lower_type_construct(struct type *type)
 
 static int lower_type_callable(struct type *type)
 {
+	/* std::function has a slight overhead compared to just using auto here,
+	 * but auto doesn't play well with recursive templates like with our
+	 * fib.fwd example, so use std::function for now. Eventually I might
+	 * instead write a C backend or something to have more control over the
+	 * exact semantics, but for now this is good enough. */
 	printf("std::function<void(");
 
 	if (lower_types(tcallable_args(type)))
@@ -317,8 +322,10 @@ static int lower_if(struct state *state, struct ast *stmt)
 	if (lower_block(state, if_body(stmt)))
 		return -1;
 
-	if (!if_else(stmt))
+	if (!if_else(stmt)) {
+		printf("\n");
 		return 0;
+	}
 
 	printf(" else ");
 	if (lower_block(state, if_else(stmt)))
@@ -403,6 +410,11 @@ static int lower_closure(struct state *state, struct ast *closure)
 
 static int lower_proto(struct ast *proc)
 {
+	/* 'extern' functions should be provided to us by whatever framework the
+	 * user is using */
+	if (!proc_body(proc))
+		return 0;
+
 	if (strcmp("main", proc_id(proc)) == 0)
 		printf("int ");
 	else
@@ -419,6 +431,9 @@ static int lower_proto(struct ast *proc)
 
 static int lower_proc(struct ast *proc)
 {
+	if (!proc_body(proc))
+		return 0;
+
 	if (strcmp("main", proc_id(proc)) == 0)
 		printf("int ");
 	else
diff --git a/src/parser.y b/src/parser.y
index 97a700e..9f532b9 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -93,8 +93,8 @@
 %left "::"
 
 %nterm <node> top unit proc call closure var expr statement body
-%nterm <node> vars exprs statements closures
-%nterm <node> opt_vars opt_exprs opt_statements
+%nterm <node> vars exprs statements closures trailing_closure
+%nterm <node> opt_vars opt_exprs opt_statements opt_trailing_closure
 %nterm <node> rev_vars rev_exprs rev_closures rev_statements
 %nterm <node> let if unop binop construct
 
@@ -197,6 +197,9 @@ proc
 	: ID "(" opt_vars ")" body {
 		$$ = gen_proc($[ID], $[opt_vars], NULL, $[body], src_loc(@$));
 	}
+	| ID "(" opt_vars ")" ";" {
+		$$ = gen_proc($[ID], $[opt_vars], NULL, NULL, src_loc(@$));
+	}
 
 binop
 	: expr "+"  expr { $$ = gen_binop(AST_ADD, $1, $3, src_loc(@$));  }
@@ -276,8 +279,22 @@ rev_closures
 	: rev_closures closure { $$ = $2; $2->n = $1; }
 	| closure
 
+trailing_closure
+	: "=>" opt_vars ";" { $$ = gen_closure($[opt_vars], NULL, src_loc(@$));}
+
+opt_trailing_closure
+	: trailing_closure
+	| { $$ = NULL; }
+
 closures
-	: rev_closures { $$ = reverse_ast_list($1); }
+	: rev_closures opt_trailing_closure {
+		if ($[opt_trailing_closure]) {
+			$[opt_trailing_closure]->n = $[rev_closures];
+			$$ = reverse_ast_list($[opt_trailing_closure]);
+		} else {
+			$$ = reverse_ast_list($[rev_closures]);
+		}
+	}
 
 call
 	: expr "(" opt_exprs ")" ";" {
@@ -307,6 +324,7 @@ statement
 	: call
 	| let
 	| if
+	| body
 	| ";" { $$ = gen_empty(src_loc(@$)); }
 
 rev_statements
-- 
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