Rustで競プロをやるための標準入力取得法

scan-stdin-once.rs

#![allow(unused_imports)]
#![cfg_attr(feature = "cargo-clippy", allow(redundant_field_names))]

#[macro_use]
mod _input {
    use std::fmt;
    use std::io::{self, Read};
    use std::str::{self, FromStr};

    macro_rules! input {
        ($($name:ident : $t:tt), *,) => {
            input!($($name: $t),*)
        };
        ($($name:ident : $t:tt), *) => {
            let ($($name, )*) = {
                let mut _scanned = ::_input::Scanned::new(::std::io::stdin(), 1024);
                $(let $name = _read_value!(_scanned, $t);)*
                ($($name, )*)
            };
            $(let _ = &$name;)*
        };
    }

    macro_rules! _read_value {
        ($scanned:expr, ($($t:tt), *)) => {
            ($(_read_value!($scanned, $t)), *)
        };
        ($scanned:expr, [$t:tt; $n:expr]) => {
            (0..$n).map(|_| _read_value!($scanned, $t)).collect::<Vec<_>>()
        };
        ($scanned:expr, _bytes) => {
            _read_value!($scanned, String).into_bytes()
        };
        ($scanned:expr, _index) => {
            _read_value!($scanned, usize) - 1
        };
        ($scanned:expr, $t:ty) => {
            $scanned.next::<$t>()
        };
    }

    #[derive(Default)]
    pub struct Scanned {
        buf: Vec<u8>,
        pos: usize,
    }

    impl Scanned {
        pub fn new<R: Read>(mut input: R, estimated: usize) -> Self {
            let mut buf = Vec::with_capacity(estimated);
            let _ = io::copy(&mut input, &mut buf).unwrap();
            // if buf.last() != Some(&b'\n') {
            //     buf.push(b'\n');
            // }
            // assert!(buf.iter().all(|&b| b <= 0x7f));
            Scanned { buf: buf, pos: 0 }
        }

        #[inline]
        pub fn next<T: FromStr>(&mut self) -> T
        where
            T::Err: fmt::Debug,
        {
            let mut start = None;
            loop {
                match (self.buf[self.pos], start.is_some()) {
                    (b' ', true) | (b'\n', true) => break,
                    (_, true) | (b' ', false) | (b'\n', false) => self.pos += 1,
                    (_, false) => start = Some(self.pos),
                }
            }
            let target = &self.buf[start.unwrap()..self.pos];
            unsafe { str::from_utf8_unchecked(target) }.parse().unwrap()
        }
    }
}

#[allow(dead_code)]
mod output {
    use std::io::{self, BufWriter, StdoutLock, Write as _Write};

    pub fn with_stdout<F: FnMut(&mut BufWriter<StdoutLock>)>(mut f: F) {
        let stdout = io::stdout();
        let mut stdout = BufWriter::new(stdout.lock());
        f(&mut stdout);
        stdout.flush().unwrap();
    }
}

use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
use std::io::Write;
use std::ops::{
    Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Div, DivAssign,
    Mul, MulAssign, Neg, Not, Rem, RemAssign, Sub, SubAssign,
};
use std::str::{self, FromStr};
use std::{char, cmp, f32, f64, fmt, i16, i32, i64, i8, thread, u16, u32, u64, u8};

fn main() {
    input! {
        n: usize,
        v: [u64; n],
    }
}

scan-stdin.rs

#![allow(unused_imports)]
#![cfg_attr(feature = "cargo-clippy", allow(redundant_field_names))]

#[macro_use]
mod _input {
    use std::fmt;
    use std::io::BufRead;
    use std::str::{self, FromStr};

    macro_rules! input {
        ($($name:ident : $t:tt), *,) => {
            input!($($name: $t),*)
        };
        ($($name:ident : $t:tt), *) => {
            let ($($name, )*) = {
                let _stdin = ::std::io::stdin();
                // ::_input::SCANNER.with(|_scanner| {
                //     let mut _scanner = _scanner.borrow_mut();
                //     $(
                //         let $name = _read_value!(_scanner, $t);
                //     )*
                //     ($($name, )*)
                // })
                let mut _scanner = ::_input::Scanner::new(
                    ::std::io::BufReader::new(_stdin.lock()),
                    1024,
                );
                $(let $name = _read_value!(_scanner, $t);)*
                ($($name, )*)
            };
            $(let _ = &$name;)*
        };
    }

    macro_rules! _read_value {
        ($scanner:expr, ($($t:tt), *)) => {
            ($(_read_value!($scanner, $t)), *)
        };
        ($scanner:expr, [$t:tt; $n:expr]) => {
            (0..$n).map(|_| _read_value!($scanner, $t)).collect::<Vec<_>>()
        };
        ($scanner:expr, _bytes) => {
            _read_value!($scanner, String).into_bytes()
        };
        ($scanner:expr, _index) => {
            _read_value!($scanner, usize) - 1
        };
        ($scanner:expr, $t:ty) => {
            $scanner.next::<$t>()
        };
    }

    // use std::cell::RefCell;
    // use std::io::{self, BufReader, Stdin};
    // thread_local! {
    //     pub static SCANNER: RefCell<Scanner<BufReader<Stdin>>> = {
    //         RefCell::new(Scanner::new(BufReader::new(io::stdin()), 0))
    //     };
    // }

    pub struct Scanner<R: BufRead> {
        rdr: R,
        buf: Vec<u8>,
        pos: usize,
    }

    impl<R: BufRead> Scanner<R> {
        pub fn new(rdr: R, capacity: usize) -> Self {
            Scanner {
                rdr: rdr,
                buf: Vec::with_capacity(capacity),
                pos: 0,
            }
        }

        #[inline]
        pub fn next<T: FromStr>(&mut self) -> T
        where
            T::Err: fmt::Debug,
        {
            if self.buf.is_empty() {
                self.read_next_line();
            }
            let mut start = None;
            loop {
                match (self.buf[self.pos], start.is_some()) {
                    // (c, _) if (c > 0x7f) => panic!("non-ASCII characer"),
                    (b' ', true) | (b'\n', true) => break,
                    (_, true) | (b' ', false) => self.pos += 1,
                    (b'\n', false) => self.read_next_line(),
                    (_, false) => start = Some(self.pos),
                }
            }
            let target = &self.buf[start.unwrap()..self.pos];
            unsafe { str::from_utf8_unchecked(target) }.parse().unwrap()
        }

        #[inline]
        fn read_next_line(&mut self) {
            self.pos = 0;
            self.buf.clear();
            if self.rdr.read_until(b'\n', &mut self.buf).unwrap() == 0 {
                panic!("reached EOF");
            }
            // if self.buf.last() != Some(&b'\n') {
            //     self.buf.push(b'\n');
            // }
        }
    }
}

use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
use std::io::Write;
use std::ops::{
    Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Div, DivAssign,
    Mul, MulAssign, Neg, Not, Rem, RemAssign, Sub, SubAssign,
};
use std::str::{self, FromStr};
use std::{char, cmp, f32, f64, fmt, i16, i32, i64, i8, thread, u16, u32, u64, u8};

fn main() {
    input! {
        n: usize,
        v: [u64; n],
    }
}