arrayvec/src/array_string.rs at specialization · Simteract/arrayvec · GitHub

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use std::borrow::Borrow;

use std::fmt;

use std::hash::{Hash, Hasher};

use std::mem;

use std::ptr;

use std::ops::{Deref, DerefMut};

use std::str;

use std::slice;

use array::Array;

use array::Index;

use CapacityError;

/// A string with a fixed capacity.

///

/// The `ArrayString` is a string backed by a fixed size array. It keeps track

/// of its length.

///

/// The string is a contiguous value that you can store directly on the stack

/// if needed.

#[derive(Copy)]

pub struct ArrayString<A: Array<Item=u8>> {

xs: A,

len: A::Index,

}

impl<A: Array<Item=u8>> ArrayString<A> {

/// Create a new empty `ArrayString`.

///

/// Capacity is inferred from the type parameter.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<[_; 16]>::new();

/// string.push_str("foo");

/// assert_eq!(&string[..], "foo");

/// assert_eq!(string.capacity(), 16);

/// ```

pub fn new() -> ArrayString<A> {

unsafe {

ArrayString {

xs: ::new_array(),

len: Index::from(0),

}

/// Create a new `ArrayString` from a `str`.

///

/// Capacity is inferred from the type parameter.

///

/// **Errors** if the backing array is not large enough to fit the string.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<[_; 3]>::from("foo").unwrap();

/// assert_eq!(&string[..], "foo");

/// assert_eq!(string.len(), 3);

/// assert_eq!(string.capacity(), 3);

/// ```

pub fn from(s: &str) -> Result<Self, CapacityError<&str>> {

let mut arraystr = Self::new();

try!(arraystr.push_str(s));

Ok(arraystr)

}

/// Return the capacity of the `ArrayString`.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let string = ArrayString::<[_; 3]>::new();

/// assert_eq!(string.capacity(), 3);

/// ```

#[inline]

pub fn capacity(&self) -> usize { A::capacity() }

/// Adds the given char to the end of the string.

///

/// Returns `Ok` if the push succeeds.

///

/// **Errors** if the backing array is not large enough to fit the additional char.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<[_; 2]>::new();

///

/// string.push('a').unwrap();

/// string.push('b').unwrap();

/// let overflow = string.push('c');

///

/// assert_eq!(&string[..], "ab");

/// assert_eq!(overflow.unwrap_err().element(), 'c');

/// ```

pub fn push(&mut self, c: char) -> Result<(), CapacityError<char>> {

use std::fmt::Write;

self.write_char(c).map_err(|_| CapacityError::new(c))

}

/// Adds the given string slice to the end of the string.

///

/// Returns `Ok` if the push succeeds.

///

/// **Errors** if the backing array is not large enough to fit the string.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<[_; 2]>::new();

///

/// string.push_str("a").unwrap();

/// let overflow1 = string.push_str("bc");

/// string.push_str("d").unwrap();

/// let overflow2 = string.push_str("ef");

///

/// assert_eq!(&string[..], "ad");

/// assert_eq!(overflow1.unwrap_err().element(), "bc");

/// assert_eq!(overflow2.unwrap_err().element(), "ef");

/// ```

pub fn push_str<'a>(&mut self, s: &'a str) -> Result<(), CapacityError<&'a str>> {

if s.len() > self.capacity() - self.len() {

return Err(CapacityError::new(s));

}

unsafe {

let dst = self.xs.as_mut_ptr().offset(self.len() as isize);

let src = s.as_ptr();

ptr::copy_nonoverlapping(src, dst, s.len());

let newl = self.len() + s.len();

self.set_len(newl);

}

Ok(())

}

/// Make the string empty.

pub fn clear(&mut self) {

unsafe {

self.set_len(0);

}

/// Set the strings's length.

///

/// May panic if `length` is greater than the capacity.

///

/// This function is `unsafe` because it changes the notion of the

/// number of “valid” bytes in the string. Use with care.

#[inline]

pub unsafe fn set_len(&mut self, length: usize) {

debug_assert!(length <= self.capacity());

self.len = Index::from(length);

}

/// Return a string slice of the whole `ArrayString`.

pub fn as_str(&self) -> &str {

self

}

impl<A: Array<Item=u8>> Deref for ArrayString<A> {

type Target = str;

#[inline]

fn deref(&self) -> &str {

unsafe {

let sl = slice::from_raw_parts(self.xs.as_ptr(), self.len.to_usize());

str::from_utf8_unchecked(sl)

}

impl<A: Array<Item=u8>> DerefMut for ArrayString<A> {

#[inline]

fn deref_mut(&mut self) -> &mut str {

unsafe {

let sl = slice::from_raw_parts_mut(self.xs.as_mut_ptr(), self.len.to_usize());

// FIXME: Nothing but transmute to do this right now

mem::transmute(sl)

}

impl<A: Array<Item=u8>> PartialEq for ArrayString<A> {

fn eq(&self, rhs: &Self) -> bool {

**self == **rhs

}

impl<A: Array<Item=u8>> PartialEq<str> for ArrayString<A> {

fn eq(&self, rhs: &str) -> bool {

&**self == rhs

}

impl<A: Array<Item=u8>> PartialEq<ArrayString<A>> for str {

fn eq(&self, rhs: &ArrayString<A>) -> bool {

self == &**rhs

}

impl<A: Array<Item=u8>> Eq for ArrayString<A> { }

impl<A: Array<Item=u8>> Hash for ArrayString<A> {

fn hash<H: Hasher>(&self, h: &mut H) {

(**self).hash(h)

}

impl<A: Array<Item=u8>> Borrow<str> for ArrayString<A> {

fn borrow(&self) -> &str { self }

}

impl<A: Array<Item=u8>> AsRef<str> for ArrayString<A> {

fn as_ref(&self) -> &str { self }

}

impl<A: Array<Item=u8>> fmt::Debug for ArrayString<A> {

fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }

}

impl<A: Array<Item=u8>> fmt::Display for ArrayString<A> {

fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }

}

/// `Write` appends written data to the end of the string.

impl<A: Array<Item=u8>> fmt::Write for ArrayString<A> {

fn write_str(&mut self, s: &str) -> fmt::Result {

self.push_str(s).map_err(|_| fmt::Error)

}

impl<A: Array<Item=u8> + Copy> Clone for ArrayString<A> {

fn clone(&self) -> ArrayString<A> {

*self

}

fn clone_from(&mut self, rhs: &Self) {

// guaranteed to fit due to types matching.

self.clear();

self.push_str(rhs).ok();

}

arrayvec/src/array_string.rs at specialization · Simteract/arrayvec · GitHub

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