6 use std::io::{Read, self};
7 use std::num::ParseIntError;
10 fn on_method() -> Result<i32, ParseIntError> {
11 Ok("1".parse::<i32>()? + "2".parse::<i32>()?)
14 fn in_chain() -> Result<String, ParseIntError> {
15 Ok("3".parse::<i32>()?.to_string())
18 fn on_call() -> Result<i32, ParseIntError> {
19 fn parse<T: FromStr>(s: &str) -> Result<T, T::Err> {
26 fn nested() -> Result<i32, ParseIntError> {
27 Ok("5".parse::<i32>()?.to_string().parse()?)
30 fn on_path() -> Result<i32, ParseIntError> {
31 let x = "6".parse::<i32>();
36 fn on_macro() -> Result<i32, ParseIntError> {
41 Ok(id!("7".parse::<i32>())?)
44 fn on_parens() -> Result<i32, ParseIntError> {
45 let x = "8".parse::<i32>();
50 fn on_block() -> Result<i32, ParseIntError> {
51 let x = "9".parse::<i32>();
56 fn on_field() -> Result<i32, ParseIntError> {
57 struct Pair<A, B> { a: A, b: B }
59 let x = Pair { a: "10".parse::<i32>(), b: 0 };
64 fn on_tuple_field() -> Result<i32, ParseIntError> {
65 let x = ("11".parse::<i32>(), 0);
70 fn on_try() -> Result<i32, ParseIntError> {
71 let x = "12".parse::<i32>().map(|i| i.to_string().parse::<i32>());
76 fn on_binary_op() -> Result<i32, ParseIntError> {
77 let x = 13 - "14".parse::<i32>()?;
78 let y = "15".parse::<i32>()? - 16;
79 let z = "17".parse::<i32>()? - "18".parse::<i32>()?;
84 fn on_index() -> Result<i32, ParseIntError> {
86 let y = "0".parse::<usize>();
91 fn on_args() -> Result<i32, ParseIntError> {
92 fn sub(x: i32, y: i32) -> i32 { x - y }
100 fn on_if() -> Result<i32, ParseIntError> {
108 fn on_if_let() -> Result<i32, ParseIntError> {
109 Ok(if let Ok(..) = "24".parse::<i32>() {
116 fn on_match() -> Result<i32, ParseIntError> {
117 Ok(match "27".parse::<i32>() {
118 Err(..) => "28".parse::<i32>(),
119 Ok(..) => "29".parse::<i32>(),
123 fn tight_binding() -> Result<bool, ()> {
124 fn ok<T>(x: T) -> Result<T, ()> { Ok(x) }
131 fn merge_error() -> Result<i32, Error> {
132 let mut s = String::new();
134 File::open("foo.txt")?.read_to_string(&mut s)?;
136 Ok(s.parse::<i32>()? + 1)
140 assert_eq!(Ok(3), on_method());
142 assert_eq!(Ok("3".to_string()), in_chain());
144 assert_eq!(Ok(4), on_call());
146 assert_eq!(Ok(5), nested());
148 assert_eq!(Ok(6), on_path());
150 assert_eq!(Ok(7), on_macro());
152 assert_eq!(Ok(8), on_parens());
154 assert_eq!(Ok(9), on_block());
156 assert_eq!(Ok(10), on_field());
158 assert_eq!(Ok(11), on_tuple_field());
160 assert_eq!(Ok(12), on_try());
162 assert_eq!(Ok(-3), on_binary_op());
164 assert_eq!(Ok(19), on_index());
166 assert_eq!(Ok(-1), on_args());
168 assert_eq!(Ok(22), on_if());
170 assert_eq!(Ok(25), on_if_let());
172 assert_eq!(Ok(29), on_match());
174 assert_eq!(Ok(false), tight_binding());
179 Parse(ParseIntError),
182 impl From<io::Error> for Error {
183 fn from(e: io::Error) -> Error {
188 impl From<ParseIntError> for Error {
189 fn from(e: ParseIntError) -> Error {