1 files changed, 72 insertions, 0 deletions
diff --git a/idreg.ha b/idreg.ha
new file mode 100644
index 0000000..1cdd74a
--- /dev/null
+++ b/idreg.ha
@@ -0,0 +1,72 @@
+use hash::fnv;
+use htab;
+use strings;
+use types;
+
+type IdRegistry = struct {
+	idtoname: []str,
+	nametoid: htab::table, // u32
+};
+
+def HTAB_EMPTY = htab::table {
+	// XXX: harec limitation...
+	table = &htab::empty,
+	nslots = 1,
+	...
+};
+
+def IDREG_EMPTY = IdRegistry {
+	nametoid = HTAB_EMPTY,
+	...
+};
+
+fn newidreg() IdRegistry =
+	IdRegistry {
+		idtoname = [],
+		nametoid = htab::new(0, size(u32)),
+	};
+
+fn idreg_count(reg: *IdRegistry) u32 =
+	len(reg.idtoname): u32;
+
+fn idreg_exists(reg: *IdRegistry, id: u32) bool =
+	id < len(reg.idtoname);
+
+fn idreg_getname(reg: *IdRegistry, id: u32) str =
+	reg.idtoname[id];
+
+fn idreg_eqfunc(ctx: *opaque, entry: *opaque) bool = {
+	const ctx = ctx: *(*IdRegistry, str);
+	return ctx.1 == ctx.0.idtoname[*(entry: *u32)];
+};
+
+fn idreg_lookup(reg: *IdRegistry, name: str) (u32 | void) = {
+	const hash = fnv::string64(name);
+	match (htab::get(&reg.nametoid, hash,
+		&idreg_eqfunc, &(reg, name), size(u32))) {
+	case let entry: *opaque =>
+		return *(entry: *u32);
+	case null => void;
+	};
+};
+
+fn idreg_register(reg: *IdRegistry, name: str) u32 = {
+	assert(idreg_lookup(reg, name) is void, "already registered");
+	assert(len(reg.idtoname) < types::U32_MAX, "registry full");
+
+	const id = len(reg.idtoname): u32;
+	append(reg.idtoname, strings::dup(name));
+
+	const hash = fnv::string64(name);
+	const entry = htab::add(&reg.nametoid, hash, size(u32));
+	*(entry: *u32) = id;
+
+	return id;
+};
+
+fn idreg_clear(reg: *IdRegistry) void = {
+	strings::freeall(reg.idtoname);
+	htab::finish(&reg.nametoid);
+	reg.idtoname = [];
+	reg.nametoid = htab::new(0, size(u32));
+};