1 files changed, 335 insertions, 0 deletions
diff --git a/core/bytes/buffer.odin b/core/bytes/buffer.odin
new file mode 100644
index 000000000..61fde9605
--- /dev/null
+++ b/core/bytes/buffer.odin
@@ -0,0 +1,335 @@
+package bytes
+
+import "core:io"
+import "core:unicode/utf8"
+
+MIN_READ :: 512;
+
+@(private)
+SMALL_BUFFER_SIZE :: 64;
+
+Buffer :: struct {
+	buf: [dynamic]byte,
+	off: int,
+	last_read: Read_Op,
+}
+
+@(private)
+Read_Op :: enum i8 {
+	Read       = -1,
+	Invalid    =  0,
+	Read_Rune1 =  1,
+	Read_Rune2 =  2,
+	Read_Rune3 =  3,
+	Read_Rune4 =  4,
+}
+
+
+buffer_init :: proc(b: ^Buffer, buf: []byte) {
+	resize(&b.buf, len(buf));
+	copy(b.buf[:], buf);
+}
+
+buffer_init_string :: proc(b: ^Buffer, s: string) {
+	resize(&b.buf, len(s));
+	copy(b.buf[:], s);
+}
+
+
+buffer_destroy :: proc(b: ^Buffer) {
+	delete(b.buf);
+	buffer_reset(b);
+}
+
+buffer_to_bytes :: proc(b: ^Buffer) -> []byte {
+	return b.buf[b.off:];
+}
+
+buffer_to_string :: proc(b: ^Buffer) -> string {
+	if b == nil {
+		return "<nil>";
+	}
+	return string(b.buf[b.off:]);
+}
+
+buffer_is_empty :: proc(b: ^Buffer) -> bool {
+	return len(b.buf) <= b.off;
+}
+
+buffer_length :: proc(b: ^Buffer) -> int {
+	return len(b.buf) - b.off;
+}
+
+buffer_capacity :: proc(b: ^Buffer) -> int {
+	return cap(b.buf);
+}
+
+buffer_reset :: proc(b: ^Buffer) {
+	clear(&b.buf);
+	b.off = 0;
+	b.last_read = .Invalid;
+}
+
+
+buffer_truncate :: proc(b: ^Buffer, n: int) {
+	if n == 0 {
+		buffer_reset(b);
+		return;
+	}
+	b.last_read = .Invalid;
+	if n < 0 || n > buffer_length(b) {
+		panic("bytes.truncate: truncation out of range");
+	}
+	resize(&b.buf, b.off+n);
+}
+
+@(private)
+_buffer_try_grow :: proc(b: ^Buffer, n: int) -> (int, bool) {
+	if l := len(b.buf); n <= cap(b.buf)-l {
+		resize(&b.buf, l+n);
+		return l, true;
+	}
+	return 0, false;
+}
+
+@(private)
+_buffer_grow :: proc(b: ^Buffer, n: int) -> int {
+	m := buffer_length(b);
+	if m == 0 && b.off != 0 {
+		buffer_reset(b);
+	}
+	if i, ok := _buffer_try_grow(b, n); ok {
+		return i;
+	}
+	if b.buf == nil && n <= SMALL_BUFFER_SIZE {
+		b.buf = make([dynamic]byte, n, SMALL_BUFFER_SIZE);
+		return 0;
+	}
+
+	c := cap(b.buf);
+	if n <= c/2 - m {
+		copy(b.buf[:], b.buf[b.off:]);
+	} else if c > max(int) - c - n {
+		panic("bytes.Buffer: too large");
+	} else {
+		resize(&b.buf, 2*c + n);
+		copy(b.buf[:], b.buf[b.off:]);
+	}
+	b.off = 0;
+	resize(&b.buf, m+n);
+	return m;
+}
+
+buffer_grow :: proc(b: ^Buffer, n: int) {
+	if n < 0 {
+		panic("bytes.buffer_grow: negative count");
+	}
+	m := _buffer_grow(b, n);
+	resize(&b.buf, m);
+}
+
+
+buffer_write :: proc(b: ^Buffer, p: []byte) -> (n: int, err: io.Error) {
+	b.last_read = .Invalid;
+	m, ok := _buffer_try_grow(b, len(p));
+	if !ok {
+		m = _buffer_grow(b, len(p));
+	}
+	return copy(b.buf[m:], p), nil;
+}
+
+buffer_write_string :: proc(b: ^Buffer, s: string) -> (n: int, err: io.Error) {
+	b.last_read = .Invalid;
+	m, ok := _buffer_try_grow(b, len(s));
+	if !ok {
+		m = _buffer_grow(b, len(s));
+	}
+	return copy(b.buf[m:], s), nil;
+}
+
+buffer_write_byte :: proc(b: ^Buffer, c: byte) -> io.Error {
+	b.last_read = .Invalid;
+	m, ok := _buffer_try_grow(b, 1);
+	if !ok {
+		m = _buffer_grow(b, 1);
+	}
+	b.buf[m] = c;
+	return nil;
+}
+
+buffer_write_rune :: proc(b: ^Buffer, r: rune) -> (n: int, err: io.Error) {
+	if r < utf8.RUNE_SELF {
+		buffer_write_byte(b, byte(r));
+		return 1, nil;
+	}
+	b.last_read = .Invalid;
+	m, ok := _buffer_try_grow(b, utf8.UTF_MAX);
+	if !ok {
+		m = _buffer_grow(b, utf8.UTF_MAX);
+	}
+	res: [4]byte;
+	res, n = utf8.encode_rune(r);
+	copy(b.buf[m:][:utf8.UTF_MAX], res[:n]);
+	resize(&b.buf, m+n);
+	return;
+}
+
+buffer_next :: proc(b: ^Buffer, n: int) -> []byte {
+	n := n;
+	b.last_read = .Invalid;
+	m := buffer_length(b);
+	if n > m {
+		n = m;
+	}
+	data := b.buf[b.off : b.off + n];
+	b.off += n;
+	if n > 0 {
+		b.last_read = .Read;
+	}
+	return data;
+}
+
+buffer_read :: proc(b: ^Buffer, p: []byte) -> (n: int, err: io.Error) {
+	b.last_read = .Invalid;
+	if buffer_is_empty(b) {
+		buffer_reset(b);
+		if len(p) == 0 {
+			return 0, nil;
+		}
+		return 0, .EOF;
+	}
+	n = copy(p, b.buf[b.off:]);
+	b.off += n;
+	if n > 0 {
+		b.last_read = .Read;
+	}
+	return;
+}
+
+buffer_read_byte :: proc(b: ^Buffer) -> (byte, io.Error) {
+	if buffer_is_empty(b) {
+		buffer_reset(b);
+		return 0, .EOF;
+	}
+	c := b.buf[b.off];
+	b.off += 1;
+	b.last_read = .Read;
+	return c, nil;
+}
+
+buffer_read_rune :: proc(b: ^Buffer) -> (r: rune, size: int, err: io.Error) {
+	if buffer_is_empty(b) {
+		buffer_reset(b);
+		return 0, 0, .EOF;
+	}
+	c := b.buf[b.off];
+	if c < utf8.RUNE_SELF {
+		b.off += 1;
+		b.last_read = .Read_Rune1;
+		return rune(c), 1, nil;
+	}
+	r, size = utf8.decode_rune(b.buf[b.off:]);
+	b.off += size;
+	b.last_read = Read_Op(i8(size));
+	return;
+}
+
+buffer_unread_byte :: proc(b: ^Buffer) -> io.Error {
+	if b.last_read == .Invalid {
+		return .Invalid_Unread;
+	}
+	b.last_read = .Invalid;
+	if b.off > 0 {
+		b.off -= 1;
+	}
+	return nil;
+}
+
+buffer_unread_rune :: proc(b: ^Buffer) -> io.Error {
+	if b.last_read <= .Invalid {
+		return .Invalid_Unread;
+	}
+	if b.off >= int(b.last_read) {
+		b.off -= int(i8(b.last_read));
+	}
+	b.last_read = .Invalid;
+	return nil;
+}
+
+
+buffer_read_bytes :: proc(b: ^Buffer, delim: byte) -> (line: []byte, err: io.Error) {
+	i := index_byte(b.buf[b.off:], delim);
+	end := b.off + i + 1;
+	if i < 0 {
+		end = len(b.buf);
+		err = .EOF;
+	}
+	line = b.buf[b.off:end];
+	b.off = end;
+	b.last_read = .Read;
+	return;
+}
+
+buffer_read_string :: proc(b: ^Buffer, delim: byte) -> (line: string, err: io.Error) {
+	slice: []byte;
+	slice, err = buffer_read_bytes(b, delim);
+	return string(slice), err;
+}
+
+
+
+buffer_to_stream :: proc(b: ^Buffer) -> (s: io.Stream) {
+	s.stream_data = b;
+	s.stream_vtable = _buffer_vtable;
+	return;
+}
+
+@(private)
+_buffer_vtable := &io.Stream_VTable{
+	impl_size = proc(s: io.Stream) -> i64 {
+		b := (^Buffer)(s.stream_data);
+		return i64(buffer_capacity(b));
+	},
+	impl_read = proc(s: io.Stream, p: []byte) -> (n: int, err: io.Error) {
+		b := (^Buffer)(s.stream_data);
+		return buffer_read(b, p);
+	},
+	impl_read_byte = proc(s: io.Stream) -> (byte, io.Error) {
+		b := (^Buffer)(s.stream_data);
+		return buffer_read_byte(b);
+	},
+	impl_read_rune = proc(s: io.Stream) -> (r: rune, size: int, err: io.Error) {
+		b := (^Buffer)(s.stream_data);
+		return buffer_read_rune(b);
+	},
+	impl_write = proc(s: io.Stream, p: []byte) -> (n: int, err: io.Error) {
+		b := (^Buffer)(s.stream_data);
+		return buffer_write(b, p);
+	},
+	impl_write_byte = proc(s: io.Stream, c: byte) -> io.Error {
+		b := (^Buffer)(s.stream_data);
+		return buffer_write_byte(b, c);
+	},
+	impl_write_rune = proc(s: io.Stream, r: rune) -> (int, io.Error) {
+		b := (^Buffer)(s.stream_data);
+		return buffer_write_rune(b, r);
+	},
+	impl_unread_byte = proc(s: io.Stream) -> io.Error {
+		b := (^Buffer)(s.stream_data);
+		return buffer_unread_byte(b);
+	},
+	impl_unread_rune = proc(s: io.Stream) -> io.Error {
+		b := (^Buffer)(s.stream_data);
+		return buffer_unread_rune(b);
+	},
+	impl_destroy = proc(s: io.Stream) -> io.Error {
+		b := (^Buffer)(s.stream_data);
+		buffer_destroy(b);
+		return nil;
+	},
+
+	// TODO(bill): write_to and read_from
+	// impl_write_to = nil,
+	// impl_read_from = nil,
+};
+