mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-29 18:23:49 +00:00
58 lines
1.5 KiB
Rust
58 lines
1.5 KiB
Rust
|
//@ known-bug: #90110
|
||
|
|
||
|
use std::fs::File;
|
||
|
use std::io::{BufReader, BufRead};
|
||
|
use std::str::Split;
|
||
|
use std::path::Path;
|
||
|
|
||
|
pub trait Parser<D>
|
||
|
where dyn Parser<D>: Sized
|
||
|
{
|
||
|
fn new(split_header: Split<&str>) -> Self where Self: Sized;
|
||
|
fn parse_line(&self, split_line: &Split<&str>) -> D;
|
||
|
}
|
||
|
|
||
|
|
||
|
pub struct CsvReader<D> {
|
||
|
parser: Box<dyn Parser<D>>,
|
||
|
|
||
|
reader: BufReader<File>,
|
||
|
buf: String, // Buffer we will read into. Avoids re-allocation on each line.
|
||
|
path: String, // Record this so we can return more informative error messages.
|
||
|
line: usize, // Same motivation for this.
|
||
|
}
|
||
|
|
||
|
impl<D> CsvReader<D>
|
||
|
where dyn Parser<D>: Sized
|
||
|
{
|
||
|
fn new<F>(path: &str, make_parser: F) -> CsvReader<D>
|
||
|
where F: Fn(Split<char>) -> dyn Parser<D> {
|
||
|
let file = match File::open(Path::new(path)) {
|
||
|
Err(err) => panic!("Couldn't read {}: {}", path, err),
|
||
|
Ok(file) => file,
|
||
|
};
|
||
|
|
||
|
let mut reader = BufReader::new(file);
|
||
|
|
||
|
let mut buf = String::new();
|
||
|
|
||
|
let parser = Box::new(match reader.read_line(&mut buf) {
|
||
|
Err(err) => panic!("Failed to read the header line from {}: {}", path, err),
|
||
|
Ok(_) => {
|
||
|
let split_header = buf.split(',');
|
||
|
make_parser(split_header)
|
||
|
},
|
||
|
});
|
||
|
|
||
|
CsvReader {
|
||
|
parser: parser,
|
||
|
reader,
|
||
|
buf,
|
||
|
path: path.to_string(),
|
||
|
line: 2,
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
pub fn main() {}
|