dupe_krill/
lazyfile.rs

1use std::path::Path;
2use std::{fs, io};
3
4/// Open the file only if necessary.
5/// The file will be closed automatically when this object goes out of scope.
6pub struct LazyFile<'a> {
7    path: &'a Path,
8    file: Option<fs::File>,
9}
10
11impl<'a> LazyFile<'a> {
12    pub fn new(path: &'a Path) -> Self {
13        LazyFile { path, file: None }
14    }
15
16    /// Open the file (or reuse already-opened handle)
17    pub fn fd(&mut self) -> Result<&mut fs::File, io::Error> {
18        if let Some(ref mut fd) = self.file {
19            Ok(fd)
20        } else {
21            self.file = Some(fs::File::open(self.path)?);
22            if let Some(ref mut fd) = self.file {
23                Ok(fd)
24            } else {
25                unreachable!();
26            }
27        }
28    }
29}
dupe_krill/lazyfile.rs

dupe_krill/
lazyfile.rs
