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libcore: update bytes/str reader to work with regions.

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This optimizes away a copy.
This commit is contained in:
Erick Tryzelaar 2012-08-21 18:32:23 -07:00
parent 6b6bea9531
commit bf0ea66dac
3 changed files with 37 additions and 50 deletions
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74
src/libcore/io.rs
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@ -272,13 +272,14 @@ fn file_reader(path: ~str) -> result<Reader, ~str> {
// Byte buffer readers
type ByteBuf = {buf: ~[const u8], mut pos: uint, len: uint};
type ByteBuf = {buf: &[const u8], mut pos: uint};
impl ByteBuf: Reader {
fn read(buf: &[mut u8], len: uint) -> uint {
let count = uint::min(len, self.len - self.pos);
let count = uint::min(len, self.buf.len() - self.pos);
vec::u8::memcpy(buf, vec::const_view(self.buf, self.pos, self.len),
vec::u8::memcpy(buf,
vec::const_view(self.buf, self.pos, self.buf.len()),
count);
self.pos += count;
@ -286,46 +287,27 @@ impl ByteBuf: Reader {
count
}
fn read_byte() -> int {
if self.pos == self.len { return -1; }
if self.pos == self.buf.len() { return -1; }
let b = self.buf[self.pos];
self.pos += 1u;
return b as int;
}
// FIXME (#2738): implement this
fn unread_byte(_byte: int) { error!("Unimplemented: unread_byte"); fail; }
fn eof() -> bool { self.pos == self.len }
fn eof() -> bool { self.pos == self.buf.len() }
fn seek(offset: int, whence: SeekStyle) {
let pos = self.pos;
self.pos = seek_in_buf(offset, pos, self.len, whence);
self.pos = seek_in_buf(offset, pos, self.buf.len(), whence);
}
fn tell() -> uint { self.pos }
}
fn bytes_reader(bytes: ~[u8]) -> Reader {
bytes_reader_between(bytes, 0u, vec::len(bytes))
fn with_bytes_reader<t>(bytes: &[u8], f: fn(Reader) -> t) -> t {
f({buf: bytes, mut pos: 0u} as Reader)
}
fn bytes_reader_between(bytes: ~[u8], start: uint, end: uint) -> Reader {
{buf: bytes, mut pos: start, len: end} as Reader
}
fn with_bytes_reader<t>(bytes: ~[u8], f: fn(Reader) -> t) -> t {
f(bytes_reader(bytes))
}
fn with_bytes_reader_between<t>(bytes: ~[u8], start: uint, end: uint,
f: fn(Reader) -> t) -> t {
f(bytes_reader_between(bytes, start, end))
}
fn str_reader(s: ~str) -> Reader {
bytes_reader(str::to_bytes(s))
}
fn with_str_reader<T>(s: ~str, f: fn(Reader) -> T) -> T {
do str::as_bytes(s) |bytes| {
with_bytes_reader_between(bytes, 0u, str::len(s), f)
}
fn with_str_reader<T>(s: &str, f: fn(Reader) -> T) -> T {
str::byte_slice(s, |bytes| with_bytes_reader(bytes, f))
}
// Writing
@ -847,9 +829,10 @@ mod tests {
#[test]
fn test_readchars_empty() {
let inp : io::Reader = io::str_reader(~"");
let res : ~[char] = inp.read_chars(128u);
assert(vec::len(res) == 0u);
do io::with_str_reader(~"") |inp| {
let res : ~[char] = inp.read_chars(128u);
assert(vec::len(res) == 0u);
}
}
#[test]
@ -862,13 +845,14 @@ mod tests {
29983, 38152, 30340, 27748,
21273, 20999, 32905, 27748];
fn check_read_ln(len : uint, s: ~str, ivals: ~[int]) {
let inp : io::Reader = io::str_reader(s);
let res : ~[char] = inp.read_chars(len);
if (len <= vec::len(ivals)) {
assert(vec::len(res) == len);
do io::with_str_reader(s) |inp| {
let res : ~[char] = inp.read_chars(len);
if (len <= vec::len(ivals)) {
assert(vec::len(res) == len);
}
assert(vec::slice(ivals, 0u, vec::len(res)) ==
vec::map(res, |x| x as int));
}
assert(vec::slice(ivals, 0u, vec::len(res)) ==
vec::map(res, |x| x as int));
}
let mut i = 0u;
while i < 8u {
@ -881,16 +865,18 @@ mod tests {
#[test]
fn test_readchar() {
let inp : io::Reader = io::str_reader(~"生");
let res : char = inp.read_char();
assert(res as int == 29983);
do io::with_str_reader(~"生") |inp| {
let res : char = inp.read_char();
assert(res as int == 29983);
}
}
#[test]
fn test_readchar_empty() {
let inp : io::Reader = io::str_reader(~"");
let res : char = inp.read_char();
assert(res as int == -1);
do io::with_str_reader(~"") |inp| {
let res : char = inp.read_char();
assert(res as int == -1);
}
}
#[test]