1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
|
#[derive(Debug,PartialEq)]
enum FileState {
Open,
Closed,
}
#[derive(Debug)]
struct File {
name: String,
data: Vec<u8>,
state: FileState,
}
impl File {
fn new(name: &str) -> File {
File { name: String::from(name), data: Vec::new(), state: FileState::Closed }
}
fn read(self: &File, save_to: &mut Vec<u8>) -> Result<usize, String> {
if self.state != FileState::Open {
return Err(String::from("File must be open for reading"));
}
let mut tmp = self.data.clone();
let read_length = tmp.len();
save_to.reserve(read_length);
save_to.append(&mut tmp);
Ok(read_length) // <6>
}
}
fn open(mut f: File) -> Result<File, String> {
f.state = FileState::Open;
Ok(f)
}
fn close(mut f: File) -> Result<File, String> {
f.state = FileState::Closed;
Ok(f)
}
fn main() {
let mut f5 = File::new("5.txt");
let mut buffer: Vec<u8> = vec![];
if f5.read(&mut buffer).is_err() {
println!("Error checking is working");
}
f5 = open(f5).unwrap(); // <9>
let f5_length = f5.read(&mut buffer).unwrap(); // <9>
f5 = close(f5).unwrap(); // <9>
let text = String::from_utf8_lossy(&buffer);
println!("{:?}", f5);
println!("{} is {} bytes long", &f5.name, f5_length);
println!("{}", text);
}
|
