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use std::error;
use std::fmt;
use std::str::FromStr;
#[derive(Debug, PartialEq)]
pub enum Error {
MissingMatch,
MissingClosingBrace,
UnexpectedValue(u8, Option<u8>),
InvalidUtf8(Vec<u8>),
PartialUtf8(usize, Vec<u8>),
Parse(String, &'static str),
#[doc(hidden)]
__NonExhaustive__,
}
impl error::Error for Error {}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use crate::Error::*;
use std::str::from_utf8;
match *self {
InvalidUtf8(ref raw) => write!(f, "input was not valid utf8: {:?}", raw),
Parse(ref s, arg) => write!(f, "could not parse {} as target type of {}", s, arg),
UnexpectedValue(exp, act) => write!(
f,
"found value {:?} not matching the pattern value {}",
act.map(|b| b as char),
exp as char
),
PartialUtf8(n, ref raw) => write!(
f,
"input was only partially valid utf8: \"{}\" followed by {:?}",
from_utf8(&raw[..n]).unwrap(),
&raw[n..]
),
MissingMatch => write!(f, "Bad read! format string: did not contain {{}}"),
MissingClosingBrace => write!(
f,
"found single open curly brace at the end of the format string"
),
__NonExhaustive__ => unreachable!(),
}
}
}
pub fn match_next(expected: u8, iter: &mut dyn Iterator<Item = u8>) -> Result<(), Error> {
let next = iter.next();
if next != Some(expected) {
return Err(Error::UnexpectedValue(expected, next))?;
}
Ok(())
}
pub fn parse_capture<T>(
name: &'static str,
next: Option<u8>,
iter: &mut dyn Iterator<Item = u8>,
) -> Result<T, Error>
where
T: FromStr,
<T as FromStr>::Err: ::std::fmt::Debug,
{
static WHITESPACES: &'static [u8] = b"\t\r\n ";
let raw: Vec<u8> = match next {
Some(c) => iter.take_while(|&ch| ch != c).collect(),
None => iter
.skip_while(|ch| WHITESPACES.contains(ch))
.take_while(|ch| !WHITESPACES.contains(ch))
.collect(),
};
match String::from_utf8(raw) {
Ok(s) => FromStr::from_str(&s).map_err(|_| Error::Parse(s, name)),
Err(e) => {
let n = e.utf8_error().valid_up_to();
let raw = e.into_bytes();
if n == 0 {
Err(Error::InvalidUtf8(raw))
} else {
Err(Error::PartialUtf8(n, raw))
}
}
}
}
#[macro_export]
macro_rules! try_read(
() => { $crate::try_read!("{}") };
($text:expr) => {{
(|| -> std::result::Result<_, $crate::Error> {
let __try_read_var__;
$crate::try_scan!($text, __try_read_var__);
Ok(__try_read_var__)
})()
}};
($text:expr, $input:expr) => {{
(|| -> std::result::Result<_, $crate::Error> {
let __try_read_var__;
$crate::try_scan!($input => $text, __try_read_var__);
Ok(__try_read_var__)
})()
}};
);
#[macro_export]
macro_rules! try_scan(
($pattern:expr, $($arg:expr),*) => {
use ::std::io::Read;
$crate::try_scan!(::std::io::stdin().bytes().map(std::result::Result::unwrap) => $pattern, $($arg),*);
format_args!($pattern, $($arg),*);
};
($input:expr => $pattern:expr, $($arg:expr),*) => {{
$crate::try_scan!(@impl question_mark; $input => $pattern, $($arg),*)
}};
(@question_mark: $($e:tt)+) => {{
($($e)+)?
}};
(@unwrap: $($e:tt)+) => {{
($($e)+).unwrap()
}};
(@impl $action:tt; $input:expr => $pattern:expr, $($arg:expr),*) => {{
#![allow(clippy::try_err)]
use $crate::{Error, match_next, parse_capture};
let pattern: &'static str = $pattern;
let stdin: &mut Iterator<Item = u8> = &mut ($input);
let mut pattern = pattern.bytes();
$(
$arg = loop {
match $crate::try_scan!(@$action: pattern.next().ok_or(Error::MissingMatch)) {
b'{' => match $crate::try_scan!(@$action: pattern.next().ok_or(Error::MissingClosingBrace)) {
b'{' => $crate::try_scan!(@$action: match_next(b'{', stdin)),
b'}' => break $crate::try_scan!(@$action: parse_capture(stringify!($arg), pattern.next(), stdin)),
_ => return $crate::try_scan!(@$action: Err(Error::MissingClosingBrace)),
},
c => $crate::try_scan!(@$action: match_next(c, stdin)),
}
};
)*
for c in pattern {
$crate::try_scan!(@$action: match_next(c, stdin))
}
format_args!($pattern, $($arg),*);
}};
);
#[macro_export]
macro_rules! read(
($($arg:tt)*) => {
$crate::try_read!($($arg)*).unwrap()
};
);
#[macro_export]
macro_rules! scan(
($text:expr, $($arg:expr),*) => {
use ::std::io::Read;
$crate::scan!(::std::io::stdin().bytes().map(std::result::Result::unwrap) => $text, $($arg),*);
format_args!($text, $($arg),*);
};
($input:expr => $pattern:expr, $($arg:expr),*) => {{
$crate::try_scan!(@impl unwrap; $input => $pattern, $($arg),*)
}};
);