src/libstd/io_util.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use core::io::{Reader, BytesReader};
  12 use core::io;
  13
  14 pub struct BufReader {
  15     buf: ~[u8],
  16     mut pos: uint
  17 }
  18
  19 pub impl BufReader {
  20     pub fn new(v: ~[u8]) -> BufReader {
  21         BufReader {
  22             buf: v,
  23             pos: 0
  24         }
  25     }
  26
  27     priv fn as_bytes_reader<A>(&self, f: &fn(&BytesReader) -> A) -> A {
  28         // Recreating the BytesReader state every call since
  29         // I can't get the borrowing to work correctly
  30         let bytes_reader = BytesReader {
  31             bytes: ::core::util::id::<&[u8]>(self.buf),
  32             pos: self.pos
  33         };
  34
  35         let res = f(&bytes_reader);
  36
  37         // FIXME #4429: This isn't correct if f fails
  38         self.pos = bytes_reader.pos;
  39
  40         return res;
  41     }
  42 }
  43
  44 impl Reader for BufReader {
  45     fn read(&self, bytes: &mut [u8], len: uint) -> uint {
  46         self.as_bytes_reader(|r| r.read(bytes, len) )
  47     }
  48     fn read_byte(&self) -> int {
  49         self.as_bytes_reader(|r| r.read_byte() )
  50     }
  51     fn eof(&self) -> bool {
  52         self.as_bytes_reader(|r| r.eof() )
  53     }
  54     fn seek(&self, offset: int, whence: io::SeekStyle) {
  55         self.as_bytes_reader(|r| r.seek(offset, whence) )
  56     }
  57     fn tell(&self) -> uint {
  58         self.as_bytes_reader(|r| r.tell() )
  59     }
  60 }