Scanner

This crate provides Java-like Scanners which can parse primitive types and strings using UTF-8 or ASCII.

Scan a stream

Scanner or ScannerAscii can be used for reading strings or raw data from a stream.

use std::io::{self, Write};

use scanner_rust::ScannerAscii;

print!("Please input two integers, a and b: ");
io::stdout().flush().unwrap();

let mut sc = ScannerAscii::new(io::stdin());

let a = {
    loop {
        match sc.next_isize() {
            Ok(i) => break i.unwrap_or(0),
            Err(_) => {
                print!("Re-input a and b: ");
                io::stdout().flush().unwrap();
            }
        }
    }
};

let b = {
    loop {
        match sc.next_isize() {
            Ok(i) => break i.unwrap_or(0),
            Err(_) => {
                print!("Re-input b: ");
                io::stdout().flush().unwrap();
            }
        }
    }
};

println!("{} + {} = {}", a, b, a + b);

Besides, the drop_next and drop_next_line methods are useful when you want to skip some data.

The default buffer size is 256 bytes. If you want to change that, you can use the new2 associated function or the scan_path2 associated function and define a length explicitly to create an instance of the above structs.

For example, to change the buffer size to 64 bytes,

use scanner_rust::generic_array::typenum::U64;
use scanner_rust::Scanner;

let mut sc: Scanner<_, U64> = Scanner::scan_path2("Cargo.toml").unwrap();

Scan a string slice (&str)

ScannerStr can be used for reading strings from a string slice.

use std::io::{self, Write};

use scanner_rust::ScannerStr;

let mut sc = ScannerStr::new(" 123   456.7    \t\r\n\n c中文字\n\tHello world!");

assert_eq!(Some(123), sc.next_u8().unwrap());
assert_eq!(Some(456.7), sc.next_f64().unwrap());
assert_eq!(Some(' '), sc.next_char().unwrap());
assert_eq!(Some(' '), sc.next_char().unwrap());
assert_eq!(true, sc.skip_whitespaces().unwrap());
assert_eq!(Some('c'), sc.next_char().unwrap());
assert_eq!(Some("中文字"), sc.next_line().unwrap());
assert_eq!(Some("\tHello world!".into()), sc.next_line().unwrap());
assert_eq!(None, sc.next_line().unwrap());

Scan a u8 slice

ScannerU8Slice or ScannerU8SliceAscii can be used for reading raw data from a u8 slice.

use std::io::{self, Write};

use scanner_rust::ScannerU8Slice;

let mut sc = ScannerU8Slice::new(" 123   456.7    \t\r\n\n c中文字\n\tHello world!".as_bytes());

assert_eq!(Some(123), sc.next_u8().unwrap());
assert_eq!(Some(456.7), sc.next_f64().unwrap());
assert_eq!(Some(' '), sc.next_char().unwrap());
assert_eq!(Some(' '), sc.next_char().unwrap());
assert_eq!(true, sc.skip_whitespaces().unwrap());
assert_eq!(Some('c'), sc.next_char().unwrap());
assert_eq!(Some("中文字".as_bytes()), sc.next_line().unwrap());
assert_eq!(Some("\tHello world!".as_bytes()), sc.next_line().unwrap());
assert_eq!(None, sc.next_line().unwrap());

Crates.io

https://crates.io/crates/scanner-rust

Documentation

https://docs.rs/scanner-rust

License

MIT