Struct regex::CaptureLocations

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pub struct CaptureLocations(/* private fields */);
Expand description

A low level representation of the byte offsets of each capture group.

You can think of this as a lower level Captures, where this type does not support named capturing groups directly and it does not borrow the haystack that these offsets were matched on.

Primarily, this type is useful when using the lower level Regex APIs such as Regex::captures_read, which permits amortizing the allocation in which capture match offsets are stored.

In order to build a value of this type, you’ll need to call the Regex::capture_locations method. The value returned can then be reused in subsequent searches for that regex. Using it for other regexes may result in a panic or otherwise incorrect results.

§Example

This example shows how to create and use CaptureLocations in a search.

use regex::Regex;

let re = Regex::new(r"(?<first>\w+)\s+(?<last>\w+)").unwrap();
let mut locs = re.capture_locations();
let m = re.captures_read(&mut locs, "Bruce Springsteen").unwrap();
assert_eq!(0..17, m.range());
assert_eq!(Some((0, 17)), locs.get(0));
assert_eq!(Some((0, 5)), locs.get(1));
assert_eq!(Some((6, 17)), locs.get(2));

// Asking for an invalid capture group always returns None.
assert_eq!(None, locs.get(3));
assert_eq!(None, locs.get(34973498648));
assert_eq!(None, locs.get(9944060567225171988));

Implementations§

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impl CaptureLocations

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pub fn get(&self, i: usize) -> Option<(usize, usize)>

Returns the start and end byte offsets of the capture group at index i. This returns None if i is not a valid capture group or if the capture group did not match.

§Example
use regex::Regex;

let re = Regex::new(r"(?<first>\w+)\s+(?<last>\w+)").unwrap();
let mut locs = re.capture_locations();
re.captures_read(&mut locs, "Bruce Springsteen").unwrap();
assert_eq!(Some((0, 17)), locs.get(0));
assert_eq!(Some((0, 5)), locs.get(1));
assert_eq!(Some((6, 17)), locs.get(2));
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pub fn len(&self) -> usize

Returns the total number of capture groups (even if they didn’t match). That is, the length returned is unaffected by the result of a search.

This is always at least 1 since every regex has at least 1 capturing group that corresponds to the entire match.

§Example
use regex::Regex;

let re = Regex::new(r"(?<first>\w+)\s+(?<last>\w+)").unwrap();
let mut locs = re.capture_locations();
assert_eq!(3, locs.len());
re.captures_read(&mut locs, "Bruce Springsteen").unwrap();
assert_eq!(3, locs.len());

Notice that the length is always at least 1, regardless of the regex:

use regex::Regex;

let re = Regex::new(r"").unwrap();
let locs = re.capture_locations();
assert_eq!(1, locs.len());

// [a&&b] is a regex that never matches anything.
let re = Regex::new(r"[a&&b]").unwrap();
let locs = re.capture_locations();
assert_eq!(1, locs.len());

Trait Implementations§

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impl Clone for CaptureLocations

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fn clone(&self) -> CaptureLocations

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for CaptureLocations

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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impl<T> Any for T
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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
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type Error = Infallible

The type returned in the event of a conversion error.
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Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.