src/test/run-pass/try-macro.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use std::num::{ParseFloatError, ParseIntError};
  12
  13 fn main() {
  14     assert_eq!(simple(), Ok(1));
  15     assert_eq!(nested(), Ok(2));
  16     assert_eq!(merge_ok(), Ok(3.0));
  17     assert_eq!(merge_int_err(), Err(Error::Int));
  18     assert_eq!(merge_float_err(), Err(Error::Float));
  19 }
  20
  21 fn simple() -> Result<i32, ParseIntError> {
  22     Ok(try!("1".parse()))
  23 }
  24
  25 fn nested() -> Result<i32, ParseIntError> {
  26     Ok(try!(try!("2".parse::<i32>()).to_string().parse::<i32>()))
  27 }
  28
  29 fn merge_ok() -> Result<f32, Error> {
  30     Ok(try!("1".parse::<i32>()) as f32 + try!("2.0".parse::<f32>()))
  31 }
  32
  33 fn merge_int_err() -> Result<f32, Error> {
  34     Ok(try!("a".parse::<i32>()) as f32 + try!("2.0".parse::<f32>()))
  35 }
  36
  37 fn merge_float_err() -> Result<f32, Error> {
  38     Ok(try!("1".parse::<i32>()) as f32 + try!("b".parse::<f32>()))
  39 }
  40
  41 #[derive(Debug, PartialEq)]
  42 enum Error {
  43     Int,
  44     Float,
  45 }
  46
  47 impl From<ParseIntError> for Error {
  48     fn from(_: ParseIntError) -> Error {
  49         Error::Int
  50     }
  51 }
  52
  53 impl From<ParseFloatError> for Error {
  54     fn from(_: ParseFloatError) -> Error {
  55         Error::Float
  56     }
  57 }