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Re-add a read_byte() method to buf_reader objs

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This was removed because of the repetition, but doing single-byte
reads in terms of read_bytes (which allocates a vec) is needlessly
slow. This change speeds up parsing by 22%.

(Eventually, we won't be able to escape handling the buffering in the
stdlib itself.)
This commit is contained in:
Marijn Haverbeke 2011-04-08 02:09:20 +02:00
parent bb56253015
commit 53cc673db1
1 changed files with 18 additions and 20 deletions
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38
src/lib/io.rs
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@ -15,6 +15,7 @@ tag seek_style {seek_set; seek_end; seek_cur;}
type buf_reader =
state obj {
impure fn read(uint len) -> vec[u8];
impure fn read_byte() -> int;
impure fn unread_byte(int byte);
impure fn eof() -> bool;
@ -60,6 +61,9 @@ state obj FILE_buf_reader(os.libc.FILE f, bool must_close) {
_vec.len_set[u8](buf, read);
ret buf;
}
impure fn read_byte() -> int {
ret os.libc.fgetc(f);
}
impure fn unread_byte(int byte) {
os.libc.ungetc(byte, f);
}
@ -77,25 +81,13 @@ state obj FILE_buf_reader(os.libc.FILE f, bool must_close) {
}
}
// FIXME: When we have a "self" keyword, move this into read_byte(). This is
// only here so that multiple method implementations below can use it.
//
// FIXME: Return value should be option[u8], not int.
impure fn read_byte_from_buf_reader(buf_reader rdr) -> int {
auto buf = rdr.read(1u);
if (_vec.len[u8](buf) == 0u) {
ret -1;
}
ret buf.(0) as int;
}
// FIXME: Convert this into pseudomethods on buf_reader.
state obj new_reader(buf_reader rdr) {
impure fn get_buf_reader() -> buf_reader {
ret rdr;
}
impure fn read_byte() -> int {
ret read_byte_from_buf_reader(rdr);
ret rdr.read_byte();
}
impure fn unread_byte(int byte) {
ret rdr.unread_byte(byte);
@ -104,7 +96,7 @@ state obj new_reader(buf_reader rdr) {
ret rdr.read(len);
}
impure fn read_char() -> char {
auto c0 = read_byte_from_buf_reader(rdr);
auto c0 = rdr.read_byte();
if (c0 == -1) {ret -1 as char;} // FIXME will this stay valid?
auto b0 = c0 as u8;
auto w = _str.utf8_char_width(b0);
@ -113,7 +105,7 @@ state obj new_reader(buf_reader rdr) {
auto val = 0u;
while (w > 1u) {
w -= 1u;
auto next = read_byte_from_buf_reader(rdr);
auto next = rdr.read_byte();
check(next > -1);
check(next & 0xc0 == 0x80);
val <<= 6u;
@ -131,7 +123,7 @@ state obj new_reader(buf_reader rdr) {
// No break yet in rustc
auto go_on = true;
while (go_on) {
auto ch = read_byte_from_buf_reader(rdr);
auto ch = rdr.read_byte();
if (ch == -1 || ch == 10) {go_on = false;}
else {_vec.push[u8](buf, ch as u8);}
}
@ -141,7 +133,7 @@ state obj new_reader(buf_reader rdr) {
let vec[u8] buf = vec();
auto go_on = true;
while (go_on) {
auto ch = read_byte_from_buf_reader(rdr);
auto ch = rdr.read_byte();
if (ch < 1) {go_on = false;}
else {_vec.push[u8](buf, ch as u8);}
}
@ -152,7 +144,7 @@ state obj new_reader(buf_reader rdr) {
auto val = 0u;
auto pos = 0u;
while (size > 0u) {
val += (read_byte_from_buf_reader(rdr) as uint) << pos;
val += (rdr.read_byte() as uint) << pos;
pos += 8u;
size -= 1u;
}
@ -162,7 +154,7 @@ state obj new_reader(buf_reader rdr) {
auto val = 0u;
auto pos = 0u;
while (size > 0u) {
val += (read_byte_from_buf_reader(rdr) as uint) << pos;
val += (rdr.read_byte() as uint) << pos;
pos += 8u;
size -= 1u;
}
@ -174,7 +166,7 @@ state obj new_reader(buf_reader rdr) {
auto sz = size; // FIXME: trans.ml bug workaround
while (sz > 0u) {
sz -= 1u;
val += (read_byte_from_buf_reader(rdr) as uint) << (sz * 8u);
val += (rdr.read_byte() as uint) << (sz * 8u);
}
ret val;
}
@ -221,6 +213,12 @@ state obj byte_buf_reader(byte_buf bbuf) {
bbuf.pos += to_read;
ret range;
}
impure fn read_byte() -> int {
if (bbuf.pos == _vec.len[u8](bbuf.buf)) {ret -1;}
auto b = bbuf.buf.(bbuf.pos);
bbuf.pos += 1u;
ret b as int;
}
impure fn unread_byte(int byte) {
log "TODO: unread_byte";