Crate yield_closures_impl[−][src]
Expand description
yield-closures
An implementation of MCP-49.
#[test]
fn decode_escape_string() {
let escaped_text = "Hello,\x20world!\\n";
let text: String = escaped_text
.chars()
.filter_map(co!(|c| {
loop {
if c != '\\' {
Not escaped
yield Some(c);
continue;
}
Go past the \
yield None;
Unescaped-char
match c {
Hexadecimal
'x' => {
yield None; Go past the x
let most = c.to_digit(16);
yield None; Go past the first digit
let least = c.to_digit(16);
Yield the decoded char if valid
yield (|| char::from_u32(most? << 4 | least?))()
}
Simple escapes
'n' => yield Some('\n'),
'r' => yield Some('\r'),
't' => yield Some('\t'),
'0' => yield Some('\0'),
'\\' => yield Some('\\'),
Unnecessary escape
_ => yield Some(c),
}
}
}))
.collect();
assert_eq!(text, "Hello, world!\n");
}
For the details of the proposal, see https://lang-team.rust-lang.org/design_notes/general_coroutines.html.
Differences between this implementation and the proposal are summarized below:
- This crate offers a macro implementation. It works with the stable Rust.
- No
FnPin
is provided. Yield closures made with this crate useBox::pin
internally and henceFnMut
. - In yield closures, one cannot use
return
expressions. - The body of a yield closure must be explosive i.e. must not return and typed by the
!
type. Thus it is compatible with both of the two designs of yield closures discussed in the document of MCP-49: poisoning by default or not.