1 files changed, 152 insertions, 0 deletions
diff --git a/nbt/load.ha b/nbt/load.ha
new file mode 100644
index 0000000..9e54bbb
--- /dev/null
+++ b/nbt/load.ha
@@ -0,0 +1,152 @@
+use endian;
+use strings;
+
+export type Invalid = !void;
+
+type Tag = enum i8 {
+	END = 0,
+	BYTE = 1,
+	SHORT = 2,
+	INT = 3,
+	LONG = 4,
+	FLOAT = 5,
+	DOUBLE = 6,
+	BYTE_ARRAY = 7,
+	STRING = 8,
+	LIST = 9,
+	COMPOUND = 10,
+	INT_ARRAY = 11,
+	LONG_ARRAY = 12,
+};
+
+// XXX: these are duplicated from mcproto; not sure what to do about that.
+
+fn decode_nbytes(in: *[]u8, length: size) ([]u8 | Invalid) = {
+	if (len(in) < length) return Invalid;
+	const res = in[..length];
+	*in = in[length..];
+	return res;
+};
+
+fn decode_byte(in: *[]u8) (i8 | Invalid) =
+	decode_nbytes(in, 1)?[0]: i8;
+fn decode_short(in: *[]u8) (i16 | Invalid) =
+	endian::begetu16(decode_nbytes(in, 2)?): i16;
+fn decode_int(in: *[]u8) (i32 | Invalid) =
+	endian::begetu32(decode_nbytes(in, 4)?): i32;
+fn decode_long(in: *[]u8) (i64 | Invalid) =
+	endian::begetu64(decode_nbytes(in, 8)?): i64;
+
+fn decode_bool(in: *[]u8) (bool | Invalid) =
+	decode_byte(in)? != 0;
+
+fn decode_float(in: *[]u8) (f32 | Invalid) =
+	*(&decode_int(in)?: *f32);
+fn decode_double(in: *[]u8) (f64 | Invalid) =
+	*(&decode_long(in)?: *f64);
+
+fn decode_string(in: *[]u8) (str | Invalid) = {
+	const length = decode_short(in)?;
+	if (length < 0) return Invalid;
+	// TODO: need to deal with braindead java utf8.
+	match (strings::fromutf8(decode_nbytes(in, length: size)?)) {
+	case let s: str =>
+		return strings::dup(s);
+	case =>
+		return Invalid;
+	};
+};
+
+// TODO: depth limit
+export fn load(in: *[]u8) ((str, Object) | Invalid) = {
+	const tag = decode_byte(in)?: Tag;
+	if (tag != Tag::COMPOUND) return Invalid;
+	const name = decode_string(in)?;
+	match (_load(in, tag)?) {
+	case let obj: Object =>
+		return (name, obj);
+	case =>
+		return Invalid;
+	};
+};
+
+fn _load(in: *[]u8, tag: Tag) (Value | Invalid) = {
+	switch (tag) {
+	case Tag::BYTE =>
+		return decode_byte(in)?;
+	case Tag::SHORT =>
+		return decode_short(in)?;
+	case Tag::INT =>
+		return decode_int(in)?;
+	case Tag::LONG =>
+		return decode_long(in)?;
+	case Tag::FLOAT =>
+		return decode_float(in)?;
+	case Tag::DOUBLE =>
+		return decode_double(in)?;
+	case Tag::STRING =>
+		return decode_string(in)?;
+	case Tag::BYTE_ARRAY =>
+		const length = decode_int(in)?;
+		if (length < 0) return Invalid;
+		return alloc(decode_nbytes(in, length: size)?...): []i8;
+	case Tag::LIST =>
+		let success = false;
+
+		const tag = decode_byte(in)?: Tag;
+		const length = decode_int(in)?;
+		if (length < 0) return Invalid;
+
+		let list = alloc([]: [0]Value, length: size);
+		defer if (!success) finish(list);
+		for (let i = 0i32; i < length; i += 1) {
+			static append(list, _load(in, tag)?);
+		};
+
+		success = true;
+		return list;
+	case Tag::COMPOUND =>
+		let success = false;
+
+		let object = newobject(0);
+		defer if (!success) finish(object);
+		for (true) {
+			const tag = decode_byte(in)?: Tag;
+			if (tag == Tag::END) break;
+			const name = decode_string(in)?;
+			defer free(name);
+			set(&object, name, _load(in, tag)?);
+		};
+
+		success = true;
+		return object;
+	case Tag::INT_ARRAY =>
+		let success = false;
+		const length = decode_int(in)?;
+		if (length < 0) return Invalid;
+
+		let array = alloc([]: [0]i32, length: size);
+		defer if (!success) free(array);
+		for (let i = 0i32; i < length; i += 1) {
+			static append(array, decode_int(in)?);
+		};
+
+		success = true;
+		return array;
+	case Tag::LONG_ARRAY =>
+		let success = false;
+		const length = decode_int(in)?;
+		if (length < 0) return Invalid;
+
+		let array = alloc([]: [0]i64, length: size);
+		defer if (!success) free(array);
+		for (let i = 0i32; i < length; i += 1) {
+			static append(array, decode_long(in)?);
+		};
+
+		success = true;
+		return array;
+	case =>
+		return Invalid;
+	};
+};