Implemented BufWriter
Filled in the implementations of Writer and Seek for BufWriter. It raises the io_error condition if a write cannot fit in the buffer. The Seek implementation for MemWriter, which was incorrectly using unsigned arithmatic to add signed offsets, has also been replaced.
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1 changed files with 99 additions and 10 deletions
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@ -14,7 +14,7 @@
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//!
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//!
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//! * Should probably have something like this for strings.
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//! * Should probably have something like this for strings.
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//! * Should they implement Closable? Would take extra state.
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//! * Should they implement Closable? Would take extra state.
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use cmp::max;
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use cmp::min;
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use cmp::min;
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use prelude::*;
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use prelude::*;
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use super::*;
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use super::*;
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@ -64,15 +64,19 @@ impl Writer for MemWriter {
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}
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}
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}
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}
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// FIXME(#10432)
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impl Seek for MemWriter {
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impl Seek for MemWriter {
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fn tell(&self) -> u64 { self.pos as u64 }
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fn tell(&self) -> u64 { self.pos as u64 }
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fn seek(&mut self, pos: i64, style: SeekStyle) {
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fn seek(&mut self, pos: i64, style: SeekStyle) {
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match style {
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// compute offset as signed and clamp to prevent overflow
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SeekSet => { self.pos = pos as uint; }
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let offset = match style {
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SeekEnd => { self.pos = self.buf.len() + pos as uint; }
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SeekSet => { 0 }
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SeekCur => { self.pos += pos as uint; }
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SeekEnd => { self.buf.len() }
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}
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SeekCur => { self.pos }
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} as i64;
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self.pos = max(0, offset+pos) as uint;
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}
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}
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}
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}
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@ -146,6 +150,9 @@ impl Decorator<~[u8]> for MemReader {
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/// Writes to a fixed-size byte slice
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/// Writes to a fixed-size byte slice
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///
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/// If a write will not fit in the buffer, it raises the `io_error`
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/// condition and does not write any data.
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pub struct BufWriter<'self> {
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pub struct BufWriter<'self> {
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priv buf: &'self mut [u8],
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priv buf: &'self mut [u8],
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priv pos: uint
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priv pos: uint
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@ -161,15 +168,38 @@ impl<'self> BufWriter<'self> {
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}
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}
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impl<'self> Writer for BufWriter<'self> {
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impl<'self> Writer for BufWriter<'self> {
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fn write(&mut self, _buf: &[u8]) { fail!() }
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fn write(&mut self, buf: &[u8]) {
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// raises a condition if the entire write does not fit in the buffer
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let max_size = self.buf.len();
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if self.pos >= max_size || (self.pos + buf.len()) > max_size {
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io_error::cond.raise(IoError {
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kind: OtherIoError,
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desc: "Trying to write past end of buffer",
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detail: None
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});
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return;
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}
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fn flush(&mut self) { fail!() }
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vec::bytes::copy_memory(self.buf.mut_slice_from(self.pos),
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buf, buf.len());
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self.pos += buf.len();
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}
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}
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}
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// FIXME(#10432)
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impl<'self> Seek for BufWriter<'self> {
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impl<'self> Seek for BufWriter<'self> {
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fn tell(&self) -> u64 { fail!() }
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fn tell(&self) -> u64 { self.pos as u64 }
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fn seek(&mut self, _pos: i64, _style: SeekStyle) { fail!() }
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fn seek(&mut self, pos: i64, style: SeekStyle) {
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// compute offset as signed and clamp to prevent overflow
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let offset = match style {
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SeekSet => { 0 }
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SeekEnd => { self.buf.len() }
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SeekCur => { self.pos }
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} as i64;
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self.pos = max(0, offset+pos) as uint;
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}
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}
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}
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@ -257,6 +287,65 @@ mod test {
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assert_eq!(*writer.inner_ref(), ~[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1]);
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assert_eq!(*writer.inner_ref(), ~[3, 4, 2, 0, 1, 5, 6, 1, 2, 0, 1]);
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}
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}
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#[test]
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fn test_buf_writer() {
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let mut buf = [0 as u8, ..8];
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{
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let mut writer = BufWriter::new(buf);
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assert_eq!(writer.tell(), 0);
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writer.write([0]);
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assert_eq!(writer.tell(), 1);
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writer.write([1, 2, 3]);
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writer.write([4, 5, 6, 7]);
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assert_eq!(writer.tell(), 8);
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}
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assert_eq!(buf, [0, 1, 2, 3, 4, 5, 6, 7]);
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}
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#[test]
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fn test_buf_writer_seek() {
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let mut buf = [0 as u8, ..8];
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{
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let mut writer = BufWriter::new(buf);
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assert_eq!(writer.tell(), 0);
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writer.write([1]);
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assert_eq!(writer.tell(), 1);
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writer.seek(2, SeekSet);
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assert_eq!(writer.tell(), 2);
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writer.write([2]);
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assert_eq!(writer.tell(), 3);
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writer.seek(-2, SeekCur);
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assert_eq!(writer.tell(), 1);
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writer.write([3]);
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assert_eq!(writer.tell(), 2);
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writer.seek(-1, SeekEnd);
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assert_eq!(writer.tell(), 7);
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writer.write([4]);
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assert_eq!(writer.tell(), 8);
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}
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assert_eq!(buf, [1, 3, 2, 0, 0, 0, 0, 4]);
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}
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#[test]
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fn test_buf_writer_error() {
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let mut buf = [0 as u8, ..2];
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let mut writer = BufWriter::new(buf);
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writer.write([0]);
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let mut called = false;
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do io_error::cond.trap(|err| {
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assert_eq!(err.kind, OtherIoError);
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called = true;
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}).inside {
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writer.write([0, 0]);
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}
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assert!(called);
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}
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#[test]
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#[test]
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fn test_mem_reader() {
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fn test_mem_reader() {
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let mut reader = MemReader::new(~[0, 1, 2, 3, 4, 5, 6, 7]);
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let mut reader = MemReader::new(~[0, 1, 2, 3, 4, 5, 6, 7]);
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