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str.rs
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str.rs
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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Unicode string manipulation (the `str` type).
//!
//! Rust's `str` type is one of the core primitive types of the language. `&str`
//! is the borrowed string type. This type of string can only be created from
//! other strings, unless it is a `&'static str` (see below). It is not possible
//! to move out of borrowed strings because they are owned elsewhere.
//!
//! # Examples
//!
//! Here's some code that uses a `&str`:
//!
//! ```
//! let s = "Hello, world.";
//! ```
//!
//! This `&str` is a `&'static str`, which is the type of string literals.
//! They're `'static` because literals are available for the entire lifetime of
//! the program.
//!
//! You can get a non-`'static` `&str` by taking a slice of a `String`:
//!
//! ```
//! # let some_string = "Hello, world.".to_string();
//! let s = &some_string;
//! ```
//!
//! # Representation
//!
//! Rust's string type, `str`, is a sequence of Unicode scalar values encoded as
//! a stream of UTF-8 bytes. All [strings](../../reference.html#literals) are
//! guaranteed to be validly encoded UTF-8 sequences. Additionally, strings are
//! not null-terminated and can thus contain null bytes.
//!
//! The actual representation of `str`s have direct mappings to slices: `&str`
//! is the same as `&[u8]`.
#![doc(primitive = "str")]
#![stable(feature = "rust1", since = "1.0.0")]
use self::RecompositionState::*;
use self::DecompositionType::*;
use core::clone::Clone;
use core::iter::{Iterator, Extend};
use core::option::Option::{self, Some, None};
use core::result::Result;
use core::str as core_str;
use core::str::pattern::Pattern;
use core::str::pattern::{Searcher, ReverseSearcher, DoubleEndedSearcher};
use rustc_unicode::str::{UnicodeStr, Utf16Encoder};
use vec_deque::VecDeque;
use borrow::{Borrow, ToOwned};
use string::String;
use rustc_unicode;
use vec::Vec;
use slice::SliceConcatExt;
pub use core::str::{FromStr, Utf8Error};
pub use core::str::{Lines, LinesAny, CharRange};
pub use core::str::{Split, RSplit};
pub use core::str::{SplitN, RSplitN};
pub use core::str::{SplitTerminator, RSplitTerminator};
pub use core::str::{Matches, RMatches};
pub use core::str::{MatchIndices, RMatchIndices};
pub use core::str::{from_utf8, Chars, CharIndices, Bytes};
pub use core::str::{from_utf8_unchecked, ParseBoolError};
pub use rustc_unicode::str::{SplitWhitespace, Words, Graphemes, GraphemeIndices};
pub use core::str::pattern;
/*
Section: Creating a string
*/
impl<S: Borrow<str>> SliceConcatExt<str> for [S] {
type Output = String;
fn concat(&self) -> String {
if self.is_empty() {
return String::new();
}
// `len` calculation may overflow but push_str will check boundaries
let len = self.iter().map(|s| s.borrow().len()).sum();
let mut result = String::with_capacity(len);
for s in self {
result.push_str(s.borrow())
}
result
}
fn connect(&self, sep: &str) -> String {
if self.is_empty() {
return String::new();
}
// concat is faster
if sep.is_empty() {
return self.concat();
}
// this is wrong without the guarantee that `self` is non-empty
// `len` calculation may overflow but push_str but will check boundaries
let len = sep.len() * (self.len() - 1)
+ self.iter().map(|s| s.borrow().len()).sum::<usize>();
let mut result = String::with_capacity(len);
let mut first = true;
for s in self {
if first {
first = false;
} else {
result.push_str(sep);
}
result.push_str(s.borrow());
}
result
}
}
/*
Section: Iterators
*/
// Helper functions used for Unicode normalization
fn canonical_sort(comb: &mut [(char, u8)]) {
let len = comb.len();
for i in 0..len {
let mut swapped = false;
for j in 1..len-i {
let class_a = comb[j-1].1;
let class_b = comb[j].1;
if class_a != 0 && class_b != 0 && class_a > class_b {
comb.swap(j-1, j);
swapped = true;
}
}
if !swapped { break; }
}
}
#[derive(Clone)]
enum DecompositionType {
Canonical,
Compatible
}
/// External iterator for a string decomposition's characters.
///
/// For use with the `std::iter` module.
#[allow(deprecated)]
#[deprecated(reason = "use the crates.io `unicode-normalization` library instead",
since = "1.0.0")]
#[derive(Clone)]
#[unstable(feature = "unicode",
reason = "this functionality may be replaced with a more generic \
unicode crate on crates.io")]
pub struct Decompositions<'a> {
kind: DecompositionType,
iter: Chars<'a>,
buffer: Vec<(char, u8)>,
sorted: bool
}
#[allow(deprecated)]
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Decompositions<'a> {
type Item = char;
#[inline]
fn next(&mut self) -> Option<char> {
match self.buffer.first() {
Some(&(c, 0)) => {
self.sorted = false;
self.buffer.remove(0);
return Some(c);
}
Some(&(c, _)) if self.sorted => {
self.buffer.remove(0);
return Some(c);
}
_ => self.sorted = false
}
if !self.sorted {
for ch in self.iter.by_ref() {
let buffer = &mut self.buffer;
let sorted = &mut self.sorted;
{
let callback = |d| {
let class =
rustc_unicode::char::canonical_combining_class(d);
if class == 0 && !*sorted {
canonical_sort(buffer);
*sorted = true;
}
buffer.push((d, class));
};
match self.kind {
Canonical => {
rustc_unicode::char::decompose_canonical(ch, callback)
}
Compatible => {
rustc_unicode::char::decompose_compatible(ch, callback)
}
}
}
if *sorted {
break
}
}
}
if !self.sorted {
canonical_sort(&mut self.buffer);
self.sorted = true;
}
if self.buffer.is_empty() {
None
} else {
match self.buffer.remove(0) {
(c, 0) => {
self.sorted = false;
Some(c)
}
(c, _) => Some(c),
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (lower, _) = self.iter.size_hint();
(lower, None)
}
}
#[derive(Clone)]
enum RecompositionState {
Composing,
Purging,
Finished
}
/// External iterator for a string recomposition's characters.
///
/// For use with the `std::iter` module.
#[allow(deprecated)]
#[deprecated(reason = "use the crates.io `unicode-normalization` library instead",
since = "1.0.0")]
#[derive(Clone)]
#[unstable(feature = "unicode",
reason = "this functionality may be replaced with a more generic \
unicode crate on crates.io")]
pub struct Recompositions<'a> {
iter: Decompositions<'a>,
state: RecompositionState,
buffer: VecDeque<char>,
composee: Option<char>,
last_ccc: Option<u8>
}
#[allow(deprecated)]
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Recompositions<'a> {
type Item = char;
#[inline]
fn next(&mut self) -> Option<char> {
loop {
match self.state {
Composing => {
for ch in self.iter.by_ref() {
let ch_class = rustc_unicode::char::canonical_combining_class(ch);
if self.composee.is_none() {
if ch_class != 0 {
return Some(ch);
}
self.composee = Some(ch);
continue;
}
let k = self.composee.clone().unwrap();
match self.last_ccc {
None => {
match rustc_unicode::char::compose(k, ch) {
Some(r) => {
self.composee = Some(r);
continue;
}
None => {
if ch_class == 0 {
self.composee = Some(ch);
return Some(k);
}
self.buffer.push_back(ch);
self.last_ccc = Some(ch_class);
}
}
}
Some(l_class) => {
if l_class >= ch_class {
// `ch` is blocked from `composee`
if ch_class == 0 {
self.composee = Some(ch);
self.last_ccc = None;
self.state = Purging;
return Some(k);
}
self.buffer.push_back(ch);
self.last_ccc = Some(ch_class);
continue;
}
match rustc_unicode::char::compose(k, ch) {
Some(r) => {
self.composee = Some(r);
continue;
}
None => {
self.buffer.push_back(ch);
self.last_ccc = Some(ch_class);
}
}
}
}
}
self.state = Finished;
if self.composee.is_some() {
return self.composee.take();
}
}
Purging => {
match self.buffer.pop_front() {
None => self.state = Composing,
s => return s
}
}
Finished => {
match self.buffer.pop_front() {
None => return self.composee.take(),
s => return s
}
}
}
}
}
}
/// External iterator for a string's UTF16 codeunits.
///
/// For use with the `std::iter` module.
#[derive(Clone)]
#[unstable(feature = "collections")]
pub struct Utf16Units<'a> {
encoder: Utf16Encoder<Chars<'a>>
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Utf16Units<'a> {
type Item = u16;
#[inline]
fn next(&mut self) -> Option<u16> { self.encoder.next() }
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) { self.encoder.size_hint() }
}
/*
Section: Misc
*/
// Return the initial codepoint accumulator for the first byte.
// The first byte is special, only want bottom 5 bits for width 2, 4 bits
// for width 3, and 3 bits for width 4
macro_rules! utf8_first_byte {
($byte:expr, $width:expr) => (($byte & (0x7F >> $width)) as u32)
}
// return the value of $ch updated with continuation byte $byte
macro_rules! utf8_acc_cont_byte {
($ch:expr, $byte:expr) => (($ch << 6) | ($byte & 63) as u32)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Borrow<str> for String {
#[inline]
fn borrow(&self) -> &str { &self[..] }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl ToOwned for str {
type Owned = String;
fn to_owned(&self) -> String {
unsafe {
String::from_utf8_unchecked(self.as_bytes().to_owned())
}
}
}
/*
Section: CowString
*/
/*
Section: Trait implementations
*/
/// Any string that can be represented as a slice.
#[lang = "str"]
#[cfg(not(test))]
#[stable(feature = "rust1", since = "1.0.0")]
impl str {
/// Escapes each char in `s` with `char::escape_default`.
#[unstable(feature = "collections",
reason = "return type may change to be an iterator")]
pub fn escape_default(&self) -> String {
self.chars().flat_map(|c| c.escape_default()).collect()
}
/// Escapes each char in `s` with `char::escape_unicode`.
#[unstable(feature = "collections",
reason = "return type may change to be an iterator")]
pub fn escape_unicode(&self) -> String {
self.chars().flat_map(|c| c.escape_unicode()).collect()
}
/// Replaces all occurrences of one string with another.
///
/// `replace` takes two arguments, a sub-`&str` to find in `self`, and a
/// second `&str` to
/// replace it with. If the original `&str` isn't found, no change occurs.
///
/// # Examples
///
/// ```
/// let s = "this is old";
///
/// assert_eq!(s.replace("old", "new"), "this is new");
/// ```
///
/// When a `&str` isn't found:
///
/// ```
/// let s = "this is old";
/// assert_eq!(s.replace("cookie monster", "little lamb"), s);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn replace(&self, from: &str, to: &str) -> String {
let mut result = String::new();
let mut last_end = 0;
for (start, end) in self.match_indices(from) {
result.push_str(unsafe { self.slice_unchecked(last_end, start) });
result.push_str(to);
last_end = end;
}
result.push_str(unsafe { self.slice_unchecked(last_end, self.len()) });
result
}
/// Returns an iterator over the string in Unicode Normalization Form D
/// (canonical decomposition).
#[allow(deprecated)]
#[deprecated(reason = "use the crates.io `unicode-normalization` library instead",
since = "1.0.0")]
#[inline]
#[unstable(feature = "unicode",
reason = "this functionality may be replaced with a more generic \
unicode crate on crates.io")]
pub fn nfd_chars(&self) -> Decompositions {
Decompositions {
iter: self[..].chars(),
buffer: Vec::new(),
sorted: false,
kind: Canonical
}
}
/// Returns an iterator over the string in Unicode Normalization Form KD
/// (compatibility decomposition).
#[allow(deprecated)]
#[deprecated(reason = "use the crates.io `unicode-normalization` library instead",
since = "1.0.0")]
#[inline]
#[unstable(feature = "unicode",
reason = "this functionality may be replaced with a more generic \
unicode crate on crates.io")]
pub fn nfkd_chars(&self) -> Decompositions {
Decompositions {
iter: self[..].chars(),
buffer: Vec::new(),
sorted: false,
kind: Compatible
}
}
/// An Iterator over the string in Unicode Normalization Form C
/// (canonical decomposition followed by canonical composition).
#[allow(deprecated)]
#[deprecated(reason = "use the crates.io `unicode-normalization` library instead",
since = "1.0.0")]
#[inline]
#[unstable(feature = "unicode",
reason = "this functionality may be replaced with a more generic \
unicode crate on crates.io")]
pub fn nfc_chars(&self) -> Recompositions {
Recompositions {
iter: self.nfd_chars(),
state: Composing,
buffer: VecDeque::new(),
composee: None,
last_ccc: None
}
}
/// An Iterator over the string in Unicode Normalization Form KC
/// (compatibility decomposition followed by canonical composition).
#[allow(deprecated)]
#[deprecated(reason = "use the crates.io `unicode-normalization` library instead",
since = "1.0.0")]
#[inline]
#[unstable(feature = "unicode",
reason = "this functionality may be replaced with a more generic \
unicode crate on crates.io")]
pub fn nfkc_chars(&self) -> Recompositions {
Recompositions {
iter: self.nfkd_chars(),
state: Composing,
buffer: VecDeque::new(),
composee: None,
last_ccc: None
}
}
/// Returns `true` if `self` contains another `&str`.
///
/// # Examples
///
/// ```
/// assert!("bananas".contains("nana"));
///
/// assert!(!"bananas".contains("foobar"));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn contains<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool {
core_str::StrExt::contains(&self[..], pat)
}
/// An iterator over the codepoints of `self`.
///
/// # Examples
///
/// ```
/// let v: Vec<char> = "abc åäö".chars().collect();
///
/// assert_eq!(v, ['a', 'b', 'c', ' ', 'å', 'ä', 'ö']);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn chars(&self) -> Chars {
core_str::StrExt::chars(&self[..])
}
/// An iterator over the bytes of `self`.
///
/// # Examples
///
/// ```
/// let v: Vec<u8> = "bors".bytes().collect();
///
/// assert_eq!(v, b"bors".to_vec());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn bytes(&self) -> Bytes {
core_str::StrExt::bytes(&self[..])
}
/// An iterator over the characters of `self` and their byte offsets.
///
/// # Examples
///
/// ```
/// let v: Vec<(usize, char)> = "abc".char_indices().collect();
/// let b = vec![(0, 'a'), (1, 'b'), (2, 'c')];
///
/// assert_eq!(v, b);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn char_indices(&self) -> CharIndices {
core_str::StrExt::char_indices(&self[..])
}
/// An iterator over substrings of `self`, separated by characters
/// matched by a pattern.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator will be double ended if the pattern allows a
/// reverse search and forward/reverse search yields the same elements.
/// This is true for, eg, `char` but not
/// for `&str`.
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, `rsplit()` can be used.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
/// assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);
///
/// let v: Vec<&str> = "".split('X').collect();
/// assert_eq!(v, [""]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
/// assert_eq!(v, ["lion", "", "tiger", "leopard"]);
///
/// let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
/// assert_eq!(v, ["lion", "tiger", "leopard"]);
/// ```
///
/// More complex patterns with closures:
///
/// ```
/// let v: Vec<&str> = "abc1def2ghi".split(|c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["abc", "def", "ghi"]);
///
/// let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
/// assert_eq!(v, ["lion", "tiger", "leopard"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn split<'a, P: Pattern<'a>>(&'a self, pat: P) -> Split<'a, P> {
core_str::StrExt::split(&self[..], pat)
}
/// An iterator over substrings of `self`, separated by characters
/// matched by a pattern and yielded in reverse order.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a
/// reverse search,
/// and it will be double ended if a forward/reverse search yields
/// the same elements.
///
/// For iterating from the front, `split()` can be used.
///
/// # Examples
///
/// Simple patterns:
///
/// ```rust
/// let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
/// assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);
///
/// let v: Vec<&str> = "".rsplit('X').collect();
/// assert_eq!(v, [""]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
/// assert_eq!(v, ["leopard", "tiger", "", "lion"]);
///
/// let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
/// assert_eq!(v, ["leopard", "tiger", "lion"]);
/// ```
///
/// More complex patterns with closures:
///
/// ```rust
/// let v: Vec<&str> = "abc1def2ghi".rsplit(|c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["ghi", "def", "abc"]);
///
/// let v: Vec<&str> = "lionXtigerXleopard".rsplit(char::is_uppercase).collect();
/// assert_eq!(v, ["leopard", "tiger", "lion"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn rsplit<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplit<'a, P>
where P::Searcher: ReverseSearcher<'a>
{
core_str::StrExt::rsplit(&self[..], pat)
}
/// An iterator over substrings of `self`, separated by characters
/// matched by a pattern.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns
/// like regular expressions.
///
/// Equivalent to `split`, except that the trailing substring
/// is skipped if empty.
///
/// This method can be used for string data that is _terminated_,
/// rather than _separated_ by a pattern.
///
/// # Iterator behavior
///
/// The returned iterator will be double ended if the pattern allows a
/// reverse search
/// and forward/reverse search yields the same elements. This is true
/// for, eg, `char` but not for `&str`.
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, `rsplit_terminator()` can be used.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "A.B.".split_terminator('.').collect();
/// assert_eq!(v, ["A", "B"]);
///
/// let v: Vec<&str> = "A..B..".split_terminator(".").collect();
/// assert_eq!(v, ["A", "", "B", ""]);
/// ```
///
/// More complex patterns with closures:
///
/// ```
/// let v: Vec<&str> = "abc1def2ghi3".split_terminator(|c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["abc", "def", "ghi"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn split_terminator<'a, P: Pattern<'a>>(&'a self, pat: P) -> SplitTerminator<'a, P> {
core_str::StrExt::split_terminator(&self[..], pat)
}
/// An iterator over substrings of `self`, separated by characters
/// matched by a pattern and yielded in reverse order.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// Equivalent to `split`, except that the trailing substring is
/// skipped if empty.
///
/// This method can be used for string data that is _terminated_,
/// rather than _separated_ by a pattern.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a
/// reverse search, and it will be double ended if a forward/reverse
/// search yields the same elements.
///
/// For iterating from the front, `split_terminator()` can be used.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
/// assert_eq!(v, ["B", "A"]);
///
/// let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
/// assert_eq!(v, ["", "B", "", "A"]);
/// ```
///
/// More complex patterns with closures:
///
/// ```
/// let v: Vec<&str> = "abc1def2ghi3".rsplit_terminator(|c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["ghi", "def", "abc"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn rsplit_terminator<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplitTerminator<'a, P>
where P::Searcher: ReverseSearcher<'a>
{
core_str::StrExt::rsplit_terminator(&self[..], pat)
}
/// An iterator over substrings of `self`, separated by a pattern,
/// restricted to returning
/// at most `count` items.
///
/// The last element returned, if any, will contain the remainder of the
/// string.
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator will not be double ended, because it is
/// not efficient to support.
///
/// If the pattern allows a reverse search, `rsplitn()` can be used.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
/// assert_eq!(v, ["Mary", "had", "a little lambda"]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
/// assert_eq!(v, ["lion", "", "tigerXleopard"]);
///
/// let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
/// assert_eq!(v, ["abcXdef"]);
///
/// let v: Vec<&str> = "".splitn(1, 'X').collect();
/// assert_eq!(v, [""]);
/// ```
///
/// More complex patterns with closures:
///
/// ```
/// let v: Vec<&str> = "abc1def2ghi".splitn(2, |c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["abc", "def2ghi"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn splitn<'a, P: Pattern<'a>>(&'a self, count: usize, pat: P) -> SplitN<'a, P> {
core_str::StrExt::splitn(&self[..], count, pat)
}
/// An iterator over substrings of `self`, separated by a pattern,
/// starting from the end of the string, restricted to returning
/// at most `count` items.
///
/// The last element returned, if any, will contain the remainder of the
/// string.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator will not be double ended, because it is not
/// efficient to support.
///
/// `splitn()` can be used for splitting from the front.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
/// assert_eq!(v, ["lamb", "little", "Mary had a"]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
/// assert_eq!(v, ["leopard", "tiger", "lionX"]);
///
/// let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
/// assert_eq!(v, ["leopard", "lion::tiger"]);
/// ```
///
/// More complex patterns with closures:
///
/// ```
/// let v: Vec<&str> = "abc1def2ghi".rsplitn(2, |c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["ghi", "abc1def"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn rsplitn<'a, P: Pattern<'a>>(&'a self, count: usize, pat: P) -> RSplitN<'a, P>
where P::Searcher: ReverseSearcher<'a>
{
core_str::StrExt::rsplitn(&self[..], count, pat)
}
/// An iterator over the matches of a pattern within `self`.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator will be double ended if the pattern allows
/// a reverse search
/// and forward/reverse search yields the same elements. This is true
/// for, eg, `char` but not
/// for `&str`.
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, `rmatches()` can be used.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
/// assert_eq!(v, ["abc", "abc", "abc"]);
///
/// let v: Vec<&str> = "1abc2abc3".matches(|c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["1", "2", "3"]);
/// ```
#[unstable(feature = "collections",
reason = "method got recently added")]
pub fn matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> Matches<'a, P> {
core_str::StrExt::matches(&self[..], pat)
}
/// An iterator over the matches of a pattern within `self`, yielded in
/// reverse order.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a
/// reverse search,
/// and it will be double ended if a forward/reverse search yields
/// the same elements.
///
/// For iterating from the front, `matches()` can be used.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
/// assert_eq!(v, ["abc", "abc", "abc"]);
///
/// let v: Vec<&str> = "1abc2abc3".rmatches(|c: char| c.is_numeric()).collect();
/// assert_eq!(v, ["3", "2", "1"]);
/// ```
#[unstable(feature = "collections",
reason = "method got recently added")]
pub fn rmatches<'a, P: Pattern<'a>>(&'a self, pat: P) -> RMatches<'a, P>
where P::Searcher: ReverseSearcher<'a>
{
core_str::StrExt::rmatches(&self[..], pat)
}
/// An iterator over the start and end indices of the disjoint matches
/// of a pattern within `self`.
///
/// For matches of `pat` within `self` that overlap, only the indices
/// corresponding to the first
/// match are returned.
///
/// The pattern can be a simple `&str`, `char`, or a closure that
/// determines
/// the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// # Iterator behavior
///
/// The returned iterator will be double ended if the pattern allows a
/// reverse search
/// and forward/reverse search yields the same elements. This is true for,
/// eg, `char` but not
/// for `&str`.
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, `rmatch_indices()` can be used.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// let v: Vec<(usize, usize)> = "abcXXXabcYYYabc".match_indices("abc").collect();
/// assert_eq!(v, [(0, 3), (6, 9), (12, 15)]);
///
/// let v: Vec<(usize, usize)> = "1abcabc2".match_indices("abc").collect();
/// assert_eq!(v, [(1, 4), (4, 7)]);
///
/// let v: Vec<(usize, usize)> = "ababa".match_indices("aba").collect();
/// assert_eq!(v, [(0, 3)]); // only the first `aba`
/// ```
#[unstable(feature = "collections",