GitCafe格调秀第二周第一题，Proof-of-concept。需要rust-peg

number_parser.rs

#![feature(plugin)]
#![feature(collections)]
#![feature(str_char)]
#![feature(convert)]
#![plugin(peg_syntax_ext)]
use std::io;
peg! pynum(r#"
digit -> i64
      = digit_nozero
      / "ling" {0i64}

digit_nozero -> i64
      = "yi" {1i64}
      / "er" {2i64}
      / "san" {3i64}
      / "si" {4i64}
      / "wu" {5i64}
      / "liu" {6i64}
      / "qi" {7i64}
      / "ba" {8i64}
      / "jiu" {9i64}

tens -> i64
     = hi:digit_nozero " shi " lo:digit {hi*10+lo}
       / "shi " lo:digit {lo+10}
       / hi:digit_nozero " shi" {hi*10}
       / "shi" {10i64}

hundreds_lo -> i64
     = " " lo:tens {lo} / " ling " lo:digit {lo}
hundreds -> i64
     = hi:digit_nozero " bai" lo:hundreds_lo? {
	     let f = hi*100;
	     if let Some(lop) = lo {
		     f + lop
	     } else {
		     f
	     }
     }
number_positive -> i64
       = hundreds / tens / digit
#[pub]
number -> i64
       = number_positive / "fu "p: number_positive {-p}
"#);

fn main() {
	let mut input = io::stdin();
	let mut line = "".to_string();
	if let Ok(_) = input.read_line(&mut line) {
		let line_str = line.as_str().trim_right();
		if let Ok(res) = pynum::number(line_str) {
			println!("{}", res);
		} else {
			println!("Parse error");
		}
	}
}