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package bytes
import "core:io"
import "core:unicode/utf8"
Reader :: struct {
s: []byte, // read-only buffer
i: i64, // current reading index
prev_rune: int, // previous reading index of rune or < 0
}
reader_init :: proc(r: ^Reader, s: []byte) {
r.s = s;
r.i = 0;
r.prev_rune = -1;
}
reader_to_stream :: proc(r: ^Reader) -> (s: io.Stream) {
s.stream_data = r;
s.stream_vtable = _reader_vtable;
return;
}
reader_length :: proc(r: ^Reader) -> int {
if r.i >= i64(len(r.s)) {
return 0;
}
return int(i64(len(r.s)) - r.i);
}
reader_size :: proc(r: ^Reader) -> i64 {
return i64(len(r.s));
}
reader_read :: proc(r: ^Reader, p: []byte) -> (n: int, err: io.Error) {
if r.i >= i64(len(r.s)) {
return 0, .EOF;
}
r.prev_rune = -1;
n = copy(p, r.s[r.i:]);
r.i += i64(n);
return;
}
reader_read_at :: proc(r: ^Reader, p: []byte, off: i64) -> (n: int, err: io.Error) {
if off < 0 {
return 0, .Invalid_Offset;
}
if off >= i64(len(r.s)) {
return 0, .EOF;
}
n = copy(p, r.s[off:]);
if n < len(p) {
err = .EOF;
}
return;
}
reader_read_byte :: proc(r: ^Reader) -> (byte, io.Error) {
r.prev_rune = -1;
if r.i >= i64(len(r.s)) {
return 0, .EOF;
}
b := r.s[r.i];
r.i += 1;
return b, nil;
}
reader_unread_byte :: proc(r: ^Reader) -> io.Error {
if r.i <= 0 {
return .Invalid_Unread;
}
r.prev_rune = -1;
r.i -= 1;
return nil;
}
reader_read_rune :: proc(r: ^Reader) -> (ch: rune, size: int, err: io.Error) {
if r.i >= i64(len(r.s)) {
r.prev_rune = -1;
return 0, 0, .EOF;
}
r.prev_rune = int(r.i);
if c := r.s[r.i]; c < utf8.RUNE_SELF {
r.i += 1;
return rune(c), 1, nil;
}
ch, size = utf8.decode_rune(r.s[r.i:]);
r.i += i64(size);
return;
}
reader_unread_rune :: proc(r: ^Reader) -> io.Error {
if r.i <= 0 {
return .Invalid_Unread;
}
if r.prev_rune < 0 {
return .Invalid_Unread;
}
r.i = i64(r.prev_rune);
r.prev_rune = -1;
return nil;
}
reader_seek :: proc(r: ^Reader, offset: i64, whence: io.Seek_From) -> (i64, io.Error) {
r.prev_rune = -1;
abs: i64;
switch whence {
case .Start:
abs = offset;
case .Current:
abs = r.i + offset;
case .End:
abs = i64(len(r.s)) + offset;
case:
return 0, .Invalid_Whence;
}
if abs < 0 {
return 0, .Invalid_Offset;
}
r.i = abs;
return abs, nil;
}
reader_write_to :: proc(r: ^Reader, w: io.Writer) -> (n: i64, err: io.Error) {
r.prev_rune = -1;
if r.i >= i64(len(r.s)) {
return 0, nil;
}
s := r.s[r.i:];
m: int;
m, err = io.write(w, s);
if m > len(s) {
panic("bytes.Reader.write_to: invalid io.write_string count");
}
r.i += i64(m);
n = i64(m);
if m != len(s) && err == nil {
err = .Short_Write;
}
return;
}
@(private)
_reader_vtable := &io.Stream_VTable{
impl_size = proc(s: io.Stream) -> i64 {
r := (^Reader)(s.stream_data);
return reader_size(r);
},
impl_read = proc(s: io.Stream, p: []byte) -> (n: int, err: io.Error) {
r := (^Reader)(s.stream_data);
return reader_read(r, p);
},
impl_read_at = proc(s: io.Stream, p: []byte, off: i64) -> (n: int, err: io.Error) {
r := (^Reader)(s.stream_data);
return reader_read_at(r, p, off);
},
impl_read_byte = proc(s: io.Stream) -> (byte, io.Error) {
r := (^Reader)(s.stream_data);
return reader_read_byte(r);
},
impl_unread_byte = proc(s: io.Stream) -> io.Error {
r := (^Reader)(s.stream_data);
return reader_unread_byte(r);
},
impl_read_rune = proc(s: io.Stream) -> (ch: rune, size: int, err: io.Error) {
r := (^Reader)(s.stream_data);
return reader_read_rune(r);
},
impl_unread_rune = proc(s: io.Stream) -> io.Error {
r := (^Reader)(s.stream_data);
return reader_unread_rune(r);
},
impl_seek = proc(s: io.Stream, offset: i64, whence: io.Seek_From) -> (i64, io.Error) {
r := (^Reader)(s.stream_data);
return reader_seek(r, offset, whence);
},
impl_write_to = proc(s: io.Stream, w: io.Writer) -> (n: i64, err: io.Error) {
r := (^Reader)(s.stream_data);
return reader_write_to(r, w);
},
};
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