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Implement new methods vec.starts_with()/vec.ends_with()

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This commit is contained in:
Kevin Ballard 2013-10-16 22:01:20 -07:00
parent d8f82c8e43
commit 2fcb53493d
4 changed files with 51 additions and 15 deletions
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46
src/libstd/vec.rs
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@ -1173,6 +1173,12 @@ pub trait ImmutableEqVector<T:Eq> {
/// Return true if a vector contains an element with the given value
fn contains(&self, x: &T) -> bool;
/// Returns true if `needle` is a prefix of the vector.
fn starts_with(&self, needle: &[T]) -> bool;
/// Returns true if `needle` is a suffix of the vector.
fn ends_with(&self, needle: &[T]) -> bool;
}
impl<'self,T:Eq> ImmutableEqVector<T> for &'self [T] {
@ -1190,6 +1196,18 @@ impl<'self,T:Eq> ImmutableEqVector<T> for &'self [T] {
fn contains(&self, x: &T) -> bool {
self.iter().any(|elt| *x == *elt)
}
#[inline]
fn starts_with(&self, needle: &[T]) -> bool {
let n = needle.len();
self.len() >= n && needle == self.slice_to(n)
}
#[inline]
fn ends_with(&self, needle: &[T]) -> bool {
let (m, n) = (self.len(), needle.len());
m >= n && needle == self.slice_from(m - n)
}
}
/// Extension methods for vectors containing `TotalOrd` elements.
@ -3828,6 +3846,34 @@ mod tests {
assert_eq!(xs.capacity(), 100);
assert_eq!(xs, range(0, 100).to_owned_vec());
}
#[test]
fn test_starts_with() {
assert!(bytes!("foobar").starts_with(bytes!("foo")));
assert!(!bytes!("foobar").starts_with(bytes!("oob")));
assert!(!bytes!("foobar").starts_with(bytes!("bar")));
assert!(!bytes!("foo").starts_with(bytes!("foobar")));
assert!(!bytes!("bar").starts_with(bytes!("foobar")));
assert!(bytes!("foobar").starts_with(bytes!("foobar")));
let empty: &[u8] = [];
assert!(empty.starts_with(empty));
assert!(!empty.starts_with(bytes!("foo")));
assert!(bytes!("foobar").starts_with(empty));
}
#[test]
fn test_ends_with() {
assert!(bytes!("foobar").ends_with(bytes!("bar")));
assert!(!bytes!("foobar").ends_with(bytes!("oba")));
assert!(!bytes!("foobar").ends_with(bytes!("foo")));
assert!(!bytes!("foo").ends_with(bytes!("foobar")));
assert!(!bytes!("bar").ends_with(bytes!("foobar")));
assert!(bytes!("foobar").ends_with(bytes!("foobar")));
let empty: &[u8] = [];
assert!(empty.ends_with(empty));
assert!(!empty.ends_with(bytes!("foo")));
assert!(bytes!("foobar").ends_with(empty));
}
}
#[cfg(test)]