expand!() { /* proc-macro */ }
Expand description
Expand byte string literals
Prefix a byte string or a string literal with a @
to expand it
Examples
expanding a byte string
assert_eq!(
&expand!([@b"Hello,", b' ', @b"world", b'!']),
b"Hello, world!",
);
expanding a string
assert_eq!(
expand!(vec![@"Hello,", ' ', @"world", '!']),
"Hello, world!".chars().collect::<Vec<char>>(),
);
pattern matching
if let expand!([@b"patt", x, y, b'n', ..]) = b"pattern matching" {
assert_eq!(x, &b'e');
assert_eq!(y, &b'r');
} else {
panic!("pattern matching failed");
}
more pattern matching
if let expand!([@b"msg = \"", xs @ .., b'"']) = br#"msg = "Hello, world!""# {
assert_eq!(xs, b"Hello, world!");
} else {
panic!("pattern matching failed");
}