From 9153fc39c4f918f5004816b8cd8db017aedd54bd Mon Sep 17 00:00:00 2001
From: Jason Heeris <jason.heeris@gmail.com>
Date: Fri, 1 Jan 2021 21:26:02 +0800
Subject: [PATCH] Add an annotation to typedef structs and enums.

A new annotation 'typedefto' allows you to make a typedef in the generated
code for structs and enums (but not union 'which' enums).
---
 compiler/c.capnp    |  3 +++
 compiler/capnpc-c.c | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/compiler/c.capnp b/compiler/c.capnp
index 2af08b9..92c955a 100644
--- a/compiler/c.capnp
+++ b/compiler/c.capnp
@@ -43,3 +43,6 @@ annotation fieldgetset @0xf72bc690355d66de (file): Void;
 annotation donotinclude @0x8c99797357b357e9 (file): UInt64;
 # do not generate an include directive for an import statement for the file with
 # the given ID
+
+annotation typedefto @0xcefaf27713042144 (struct, enum): Text;
+# generate a typedef for the annotated struct or enum declaration
diff --git a/compiler/capnpc-c.c b/compiler/capnpc-c.c
index f21e913..2512f13 100644
--- a/compiler/capnpc-c.c
+++ b/compiler/capnpc-c.c
@@ -191,6 +191,24 @@ static void define_enum(struct node *n) {
 		str_addf(&HDR, "\n\t%s_%s = %d", n->name.str, e.name.str, i);
 	}
 	str_addf(&HDR, "\n};\n");
+
+	for (i = capn_len(n->n.annotations)-1; i >= 0; i--) {
+		struct Annotation a;
+		struct Value v;
+		get_Annotation(&a, n->n.annotations, i);
+		read_Value(&v, a.value);
+
+		switch (a.id) {
+		case 0xcefaf27713042144UL:
+			if (v.which != Value_text) {
+				fprintf(stderr, "schema breakage on $C::typedefto annotation\n");
+				exit(2);
+			}
+
+			str_addf(&HDR, "\ntypedef enum %s %s;\n", n->name.str, v.text.str);
+			break;
+		}
+	}
 }
 
 static void decode_value(struct value* v, Type_ptr type, Value_ptr value, const char *symbol) {
@@ -1007,6 +1025,7 @@ static void define_group(struct strings *s, struct node *n, const char *group_na
 
 static void define_struct(struct node *n) {
 	static struct strings s;
+	int i;
 
 	str_reset(&s.dtab);
 	str_reset(&s.ftab);
@@ -1034,6 +1053,24 @@ static void define_struct(struct node *n) {
 	str_add(&HDR, s.decl.str, s.decl.len);
 	str_addf(&HDR, "};\n");
 
+	for (i = capn_len(n->n.annotations)-1; i >= 0; i--) {
+		struct Annotation a;
+		struct Value v;
+		get_Annotation(&a, n->n.annotations, i);
+		read_Value(&v, a.value);
+
+		switch (a.id) {
+		case 0xcefaf27713042144UL:
+			if (v.which != Value_text) {
+				fprintf(stderr, "schema breakage on $C::typedefto annotation\n");
+				exit(2);
+			}
+
+			str_addf(&HDR, "\ntypedef struct %s %s;\n", n->name.str, v.text.str);
+			break;
+		}
+	}
+
 	str_addf(&SRC, "\n%s_ptr new_%s(struct capn_segment *s) {\n", n->name.str, n->name.str);
 	str_addf(&SRC, "\t%s_ptr p;\n", n->name.str);
 	str_addf(&SRC, "\tp.p = capn_new_struct(s, %d, %d);\n", 8*n->n._struct.dataWordCount, n->n._struct.pointerCount);