# Struct regex_syntax::ByteClass [−] [src]

    pub struct ByteClass {
        // some fields omitted
    }

A byte class for byte ranges only.

A byte class has a canonical format that the parser guarantees. Its canonical format is defined by the following invariants:

1. Given any byte, it is matched by at most one byte range in a canonical character class.
2. Every adjacent byte range is separated by at least one byte.
3. Given any pair of byte ranges `r1` and `r2`, if `r1.end < r2.start`, then `r1` comes before `r2` in a canonical character class.

In sum, any `ByteClass` produced by this crate's parser is a sorted sequence of non-overlapping ranges. This makes it possible to test whether a byte is matched by a class with a binary search.

If the case insensitive flag was set when parsing a character class, then simple ASCII-only case folding is done automatically. For example, `(?i)[a-c]` is automatically translated to `[a-cA-C]`.

## Methods

### `impl ByteClass`

#### `fn new(ranges: Vec<ByteRange>) -> ByteClass`

Create a new class from an existing set of ranges.

#### `fn matches(&self, b: u8) -> bool`

Returns true if `b` is matched by this byte class.

#### `fn remove(&mut self, b: u8)`

Removes the given byte from the class if it exists.

Note that this takes `O(n)` time in the number of ranges.

#### `fn negate(self) -> ByteClass`

Negates the byte class.

For all `b` where `b` is a byte, `b` matches `self` if and only if `b` does not match `self.negate()`.

#### `fn case_fold(self) -> ByteClass`

Apply case folding to this byte class.

This assumes that the bytes in the ranges are ASCII compatible.

N.B. Applying case folding to a negated character class probably won't produce the expected result. e.g., `(?i)[^x]` really should match any character sans `x` and `X`, but if `[^x]` is negated before being case folded, you'll end up matching any character.

## Methods from Deref<Target=Vec<ByteRange>>

#### `fn capacity(&self) -> usize` 1.0.0

Returns the number of elements the vector can hold without reallocating.

# Examples

    let vec: Vec<i32> = Vec::with_capacity(10);
    assert_eq!(vec.capacity(), 10);

#### `fn reserve(&mut self, additional: usize)`1.0.0

Reserves capacity for at least `additional` more elements to be inserted in the given `Vec<T>`. The collection may reserve more space to avoid frequent reallocations.

# Panics

Panics if the new capacity overflows `usize`.

# Examples

    let mut vec = vec![1];
    vec.reserve(10);
    assert!(vec.capacity() >= 11);

#### `fn reserve_exact(&mut self, additional: usize)`1.0.0

Reserves the minimum capacity for exactly `additional` more elements to be inserted in the given `Vec<T>`. Does nothing if the capacity is already sufficient.

Note that the allocator may give the collection more space than it requests. Therefore capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future insertions are expected.

# Panics

Panics if the new capacity overflows `usize`.

# Examples

    let mut vec = vec![1];
    vec.reserve_exact(10);
    assert!(vec.capacity() >= 11);

#### `fn shrink_to_fit(&mut self)`1.0.0

Shrinks the capacity of the vector as much as possible.

It will drop down as close as possible to the length but the allocator may still inform the vector that there is space for a few more elements.

# Examples

    let mut vec = Vec::with_capacity(10);
    vec.extend([1, 2, 3].iter().cloned());
    assert_eq!(vec.capacity(), 10);
    vec.shrink_to_fit();
    assert!(vec.capacity() >= 3);

#### `fn into_boxed_slice(self) -> Box<[T]>`1.0.0

Converts the vector into Box<[T]>.

Note that this will drop any excess capacity. Calling this and converting back to a vector with `into_vec()` is equivalent to calling `shrink_to_fit()`.

#### `fn truncate(&mut self, len: usize)`1.0.0

Shorten a vector to be `len` elements long, dropping excess elements.

If `len` is greater than the vector's current length, this has no effect.

# Examples

    let mut vec = vec![1, 2, 3, 4, 5];
    vec.truncate(2);
    assert_eq!(vec, [1, 2]);

#### `fn as_slice(&self) -> &[T]`1.7.0

Extracts a slice containing the entire vector.

Equivalent to `&s[..]`.

#### `fn as_mut_slice(&mut self) -> &mut [T]`1.7.0

Extracts a mutable slice of the entire vector.

Equivalent to `&mut s[..]`.

#### `unsafe fn set_len(&mut self, len: usize)`1.0.0

Sets the length of a vector.

This will explicitly set the size of the vector, without actually modifying its buffers, so it is up to the caller to ensure that the vector is actually the specified size.

# Examples

    let mut v = vec![1, 2, 3, 4];
    unsafe {
        v.set_len(1);
    }

#### `fn swap_remove(&mut self, index: usize) -> T` 1.0.0

Removes an element from anywhere in the vector and return it, replacing it with the last element.

This does not preserve ordering, but is O(1).

# Panics

Panics if `index` is out of bounds.

# Examples

    let mut v = vec!["foo", "bar", "baz", "qux"];

    assert_eq!(v.swap_remove(1), "bar");
    assert_eq!(v, ["foo", "qux", "baz"]);

    assert_eq!(v.swap_remove(0), "foo");
    assert_eq!(v, ["baz", "qux"]);

#### `fn insert(&mut self, index: usize, element: T)`1.0.0

Inserts an element at position `index` within the vector, shifting all elements after it to the right.

# Panics

Panics if `index` is greater than the vector's length.

# Examples

    let mut vec = vec![1, 2, 3];
    vec.insert(1, 4);
    assert_eq!(vec, [1, 4, 2, 3]);
    vec.insert(4, 5);
    assert_eq!(vec, [1, 4, 2, 3, 5]);

#### `fn remove(&mut self, index: usize) -> T` 1.0.0

Removes and returns the element at position `index` within the vector, shifting all elements after it to the left.

# Panics

Panics if `index` is out of bounds.

# Examples

    let mut v = vec![1, 2, 3];
    assert_eq!(v.remove(1), 2);
    assert_eq!(v, [1, 3]);

#### `fn retain<F>(&mut self, f: F) where F: FnMut(&T) -> bool` 1.0.0

Retains only the elements specified by the predicate.

In other words, remove all elements `e` such that `f(&e)` returns false. This method operates in place and preserves the order of the retained elements.

# Examples

    let mut vec = vec![1, 2, 3, 4];
    vec.retain(|&x| x%2 == 0);
    assert_eq!(vec, [2, 4]);

#### `fn push(&mut self, value: T)`1.0.0

Appends an element to the back of a collection.

# Panics

Panics if the number of elements in the vector overflows a `usize`.

# Examples

    let mut vec = vec![1, 2];
    vec.push(3);
    assert_eq!(vec, [1, 2, 3]);

#### `fn pop(&mut self) -> Option<T>`1.0.0

Removes the last element from a vector and returns it, or `None` if it is empty.

# Examples

    let mut vec = vec![1, 2, 3];
    assert_eq!(vec.pop(), Some(3));
    assert_eq!(vec, [1, 2]);

#### `fn append(&mut self, other: &mut Vec<T>)`1.4.0

Moves all the elements of `other` into `Self`, leaving `other` empty.

# Panics

Panics if the number of elements in the vector overflows a `usize`.

# Examples

    let mut vec = vec![1, 2, 3];
    let mut vec2 = vec![4, 5, 6];
    vec.append(&mut vec2);
    assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
    assert_eq!(vec2, []);

#### `fn drain<R>(&mut self, range: R) -> Drain<T> where R: RangeArgument<usize>`1.6.0

Create a draining iterator that removes the specified range in the vector and yields the removed items.

Note 1: The element range is removed even if the iterator is not consumed until the end.

Note 2: It is unspecified how many elements are removed from the vector, if the `Drain` value is leaked.

# Panics

Panics if the starting point is greater than the end point or if the end point is greater than the length of the vector.

# Examples

    let mut v = vec![1, 2, 3];
    let u: Vec<_> = v.drain(1..).collect();
    assert_eq!(v, &[1]);
    assert_eq!(u, &[2, 3]);

    // A full range clears the vector
    v.drain(..);
    assert_eq!(v, &[]);

#### `fn clear(&mut self)`1.0.0

Clears the vector, removing all values.

# Examples

    let mut v = vec![1, 2, 3];

    v.clear();

    assert!(v.is_empty());

#### `fn len(&self) -> usize` 1.0.0

Returns the number of elements in the vector.

# Examples

    let a = vec![1, 2, 3];
    assert_eq!(a.len(), 3);

#### `fn is_empty(&self) -> bool` 1.0.0

Returns `true` if the vector contains no elements.

# Examples

    let mut v = Vec::new();
    assert!(v.is_empty());

    v.push(1);
    assert!(!v.is_empty());

#### `fn split_off(&mut self, at: usize) -> Vec<T>`1.4.0

Splits the collection into two at the given index.

Returns a newly allocated `Self`. `self` contains elements `[0, at)`, and the returned `Self` contains elements `[at, len)`.

Note that the capacity of `self` does not change.

# Panics

Panics if `at > len`.

# Examples

    let mut vec = vec![1,2,3];
    let vec2 = vec.split_off(1);
    assert_eq!(vec, [1]);
    assert_eq!(vec2, [2, 3]);

#### `fn resize(&mut self, new_len: usize, value: T)`1.5.0

Resizes the `Vec` in-place so that `len()` is equal to `new_len`.

If `new_len` is greater than `len()`, the `Vec` is extended by the difference, with each additional slot filled with `value`. If `new_len` is less than `len()`, the `Vec` is simply truncated.

# Examples

    let mut vec = vec!["hello"];
    vec.resize(3, "world");
    assert_eq!(vec, ["hello", "world", "world"]);

    let mut vec = vec![1, 2, 3, 4];
    vec.resize(2, 0);
    assert_eq!(vec, [1, 2]);

#### `fn extend_from_slice(&mut self, other: &[T])`1.6.0

Appends all elements in a slice to the `Vec`.

Iterates over the slice `other`, clones each element, and then appends it to this `Vec`. The `other` vector is traversed in-order.

Note that this function is same as `extend` except that it is specialized to work with slices instead. If and when Rust gets specialization this function will likely be deprecated (but still available).

# Examples

    let mut vec = vec![1];
    vec.extend_from_slice(&[2, 3, 4]);
    assert_eq!(vec, [1, 2, 3, 4]);

#### `fn dedup(&mut self)`1.0.0

Removes consecutive repeated elements in the vector.

If the vector is sorted, this removes all duplicates.

# Examples

    let mut vec = vec![1, 2, 2, 3, 2];

    vec.dedup();

    assert_eq!(vec, [1, 2, 3, 2]);

## Trait Implementations

### `impl Deref for ByteClass`

#### `type Target = Vec<ByteRange>`

#### `fn deref(&self) -> &Vec<ByteRange>`

### `impl IntoIterator for ByteClass`

#### `type Item = ByteRange`

#### `type IntoIter = IntoIter<ByteRange>`

#### `fn into_iter(self) -> IntoIter<ByteRange>`

### `impl<'a> IntoIterator for &'a ByteClass`

#### `type Item = &'a ByteRange`

#### `type IntoIter = Iter<'a, ByteRange>`

#### `fn into_iter(self) -> Iter<'a, ByteRange>`

### `impl Display for ByteClass`

#### `fn fmt(&self, f: &mut Formatter) -> Result`

### Derived Implementations

### `impl Eq for ByteClass`

### `impl PartialEq for ByteClass`

#### `fn eq(&self, __arg_0: &ByteClass) -> bool`

#### `fn ne(&self, __arg_0: &ByteClass) -> bool`

### `impl Debug for ByteClass`

#### `fn fmt(&self, __arg_0: &mut Formatter) -> Result`

### `impl Clone for ByteClass`

#### `fn clone(&self) -> ByteClass`

#### `fn clone_from(&mut self, source: &Self)`1.0.0

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