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rust/src/libcore/str/mod.rs
Alex Crichton 54452cdd68 std: Second pass stabilization for ptr 
This commit performs a second pass for stabilization over the `std::ptr` module.
The specific actions taken were:

* The `RawPtr` trait was renamed to `PtrExt`
* The `RawMutPtr` trait was renamed to `MutPtrExt`
* The module name `ptr` is now stable.
* These functions were all marked `#[stable]` with no modification:
  * `null`
  * `null_mut`
  * `swap`
  * `replace`
  * `read`
  * `write`
  * `PtrExt::is_null`
  * `PtrExt::offset`
* These functions remain unstable:
  * `as_ref`, `as_mut` - the return value of an `Option` is not fully expressive
                         as null isn't the only bad value, and it's unclear
                         whether we want to commit to these functions at this
                         time. The reference/lifetime semantics as written are
                         also problematic in how they encourage arbitrary
                         lifetimes.
  * `zero_memory` - This function is currently not used at all in the
                    distribution, and in general it plays a broader role in the
                    "working with unsafe pointers" story. This story is not yet
                    fully developed, so at this time the function remains
                    unstable for now.
  * `read_and_zero` - This function remains unstable for largely the same
                      reasons as `zero_memory`.
* These functions are now all deprecated:
  * `PtrExt::null` - call `ptr::null` or `ptr::null_mut` instead.
  * `PtrExt::to_uint` - use an `as` expression instead.
  * `PtrExt::is_not_null` - use `!p.is_null()` instead.
2014-12-29 15:57:28 -08:00

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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.
//
// ignore-lexer-test FIXME #15679
//! String manipulation
//!
//! For more details, see std::str
#![doc(primitive = "str")]
use self::Searcher::{Naive, TwoWay, TwoWayLong};
use cmp::{mod, Eq};
use default::Default;
use iter::range;
use iter::{DoubleEndedIteratorExt, ExactSizeIterator};
use iter::{Map, Iterator, IteratorExt, DoubleEndedIterator};
use kinds::Sized;
use mem;
use num::Int;
use ops::{Fn, FnMut};
use option::Option::{mod, None, Some};
use ptr::PtrExt;
use raw::{Repr, Slice};
use result::Result::{mod, Ok, Err};
use slice::{mod, SliceExt};
use uint;
macro_rules! delegate_iter {
(exact $te:ty in $ti:ty) => {
delegate_iter!{$te in $ti}
impl<'a> ExactSizeIterator<$te> for $ti {
#[inline]
fn rposition<P>(&mut self, predicate: P) -> Option<uint> where P: FnMut($te) -> bool{
self.0.rposition(predicate)
}
#[inline]
fn len(&self) -> uint {
self.0.len()
}
}
};
($te:ty in $ti:ty) => {
impl<'a> Iterator<$te> for $ti {
#[inline]
fn next(&mut self) -> Option<$te> {
self.0.next()
}
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) {
self.0.size_hint()
}
}
impl<'a> DoubleEndedIterator<$te> for $ti {
#[inline]
fn next_back(&mut self) -> Option<$te> {
self.0.next_back()
}
}
};
(pattern $te:ty in $ti:ty) => {
impl<'a, P: CharEq> Iterator<$te> for $ti {
#[inline]
fn next(&mut self) -> Option<$te> {
self.0.next()
}
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) {
self.0.size_hint()
}
}
impl<'a, P: CharEq> DoubleEndedIterator<$te> for $ti {
#[inline]
fn next_back(&mut self) -> Option<$te> {
self.0.next_back()
}
}
};
(pattern forward $te:ty in $ti:ty) => {
impl<'a, P: CharEq> Iterator<$te> for $ti {
#[inline]
fn next(&mut self) -> Option<$te> {
self.0.next()
}
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) {
self.0.size_hint()
}
}
}
}
/// A trait to abstract the idea of creating a new instance of a type from a
/// string.
// FIXME(#17307): there should be an `E` associated type for a `Result` return
#[unstable = "will return a Result once associated types are working"]
pub trait FromStr {
/// Parses a string `s` to return an optional value of this type. If the
/// string is ill-formatted, the None is returned.
fn from_str(s: &str) -> Option<Self>;
}
/// A utility function that just calls FromStr::from_str
#[deprecated = "call the .parse() method on the string instead"]
pub fn from_str<A: FromStr>(s: &str) -> Option<A> {
FromStr::from_str(s)
}
impl FromStr for bool {
/// Parse a `bool` from a string.
///
/// Yields an `Option<bool>`, because `s` may or may not actually be parseable.
///
/// # Examples
///
/// ```rust
/// assert_eq!("true".parse(), Some(true));
/// assert_eq!("false".parse(), Some(false));
/// assert_eq!("not even a boolean".parse::<bool>(), None);
/// ```
#[inline]
fn from_str(s: &str) -> Option<bool> {
match s {
"true" => Some(true),
"false" => Some(false),
_ => None,
}
}
}
/*
Section: Creating a string
*/
/// Errors which can occur when attempting to interpret a byte slice as a `str`.
#[deriving(Copy, Eq, PartialEq, Clone)]
pub enum Utf8Error {
/// An invalid byte was detected at the byte offset given.
///
/// The offset is guaranteed to be in bounds of the slice in question, and
/// the byte at the specified offset was the first invalid byte in the
/// sequence detected.
InvalidByte(uint),
/// The byte slice was invalid because more bytes were needed but no more
/// bytes were available.
TooShort,
}
/// Converts a slice of bytes to a string slice without performing any
/// allocations.
///
/// Once the slice has been validated as utf-8, it is transmuted in-place and
/// returned as a '&str' instead of a '&[u8]'
///
/// # Failure
///
/// Returns `Err` if the slice is not utf-8 with a description as to why the
/// provided slice is not utf-8.
pub fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error> {
try!(run_utf8_validation_iterator(&mut v.iter()));
Ok(unsafe { from_utf8_unchecked(v) })
}
/// Converts a slice of bytes to a string slice without checking
/// that the string contains valid UTF-8.
#[stable]
pub unsafe fn from_utf8_unchecked<'a>(v: &'a [u8]) -> &'a str {
mem::transmute(v)
}
/// Constructs a static string slice from a given raw pointer.
///
/// This function will read memory starting at `s` until it finds a 0, and then
/// transmute the memory up to that point as a string slice, returning the
/// corresponding `&'static str` value.
///
/// This function is unsafe because the caller must ensure the C string itself
/// has the static lifetime and that the memory `s` is valid up to and including
/// the first null byte.
///
/// # Panics
///
/// This function will panic if the string pointed to by `s` is not valid UTF-8.
#[unstable = "may change location based on the outcome of the c_str module"]
pub unsafe fn from_c_str(s: *const i8) -> &'static str {
let s = s as *const u8;
let mut len = 0u;
while *s.offset(len as int) != 0 {
len += 1u;
}
let v: &'static [u8] = ::mem::transmute(Slice { data: s, len: len });
from_utf8(v).ok().expect("from_c_str passed invalid utf-8 data")
}
/// Something that can be used to compare against a character
#[unstable = "definition may change as pattern-related methods are stabilized"]
pub trait CharEq {
/// Determine if the splitter should split at the given character
fn matches(&mut self, char) -> bool;
/// Indicate if this is only concerned about ASCII characters,
/// which can allow for a faster implementation.
fn only_ascii(&self) -> bool;
}
impl CharEq for char {
#[inline]
fn matches(&mut self, c: char) -> bool { *self == c }
#[inline]
fn only_ascii(&self) -> bool { (*self as uint) < 128 }
}
impl<F> CharEq for F where F: FnMut(char) -> bool {
#[inline]
fn matches(&mut self, c: char) -> bool { (*self)(c) }
#[inline]
fn only_ascii(&self) -> bool { false }
}
impl<'a> CharEq for &'a [char] {
#[inline]
fn matches(&mut self, c: char) -> bool {
self.iter().any(|&mut m| m.matches(c))
}
#[inline]
fn only_ascii(&self) -> bool {
self.iter().all(|m| m.only_ascii())
}
}
/*
Section: Iterators
*/
/// Iterator for the char (representing *Unicode Scalar Values*) of a string
///
/// Created with the method `.chars()`.
#[deriving(Clone, Copy)]
pub struct Chars<'a> {
iter: slice::Iter<'a, u8>
}
// 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) | ($byte & CONT_MASK) as u32)
}
macro_rules! utf8_is_cont_byte {
($byte:expr) => (($byte & !CONT_MASK) == TAG_CONT_U8)
}
#[inline]
fn unwrap_or_0(opt: Option<&u8>) -> u8 {
match opt {
Some(&byte) => byte,
None => 0,
}
}
impl<'a> Iterator<char> for Chars<'a> {
#[inline]
fn next(&mut self) -> Option<char> {
// Decode UTF-8, using the valid UTF-8 invariant
let x = match self.iter.next() {
None => return None,
Some(&next_byte) if next_byte < 128 => return Some(next_byte as char),
Some(&next_byte) => next_byte,
};
// Multibyte case follows
// Decode from a byte combination out of: [[[x y] z] w]
// NOTE: Performance is sensitive to the exact formulation here
let init = utf8_first_byte!(x, 2);
let y = unwrap_or_0(self.iter.next());
let mut ch = utf8_acc_cont_byte!(init, y);
if x >= 0xE0 {
// [[x y z] w] case
// 5th bit in 0xE0 .. 0xEF is always clear, so `init` is still valid
let z = unwrap_or_0(self.iter.next());
let y_z = utf8_acc_cont_byte!((y & CONT_MASK) as u32, z);
ch = init << 12 | y_z;
if x >= 0xF0 {
// [x y z w] case
// use only the lower 3 bits of `init`
let w = unwrap_or_0(self.iter.next());
ch = (init & 7) << 18 | utf8_acc_cont_byte!(y_z, w);
}
}
// str invariant says `ch` is a valid Unicode Scalar Value
unsafe {
Some(mem::transmute(ch))
}
}
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) {
let (len, _) = self.iter.size_hint();
(len.saturating_add(3) / 4, Some(len))
}
}
impl<'a> DoubleEndedIterator<char> for Chars<'a> {
#[inline]
fn next_back(&mut self) -> Option<char> {
let w = match self.iter.next_back() {
None => return None,
Some(&back_byte) if back_byte < 128 => return Some(back_byte as char),
Some(&back_byte) => back_byte,
};
// Multibyte case follows
// Decode from a byte combination out of: [x [y [z w]]]
let mut ch;
let z = unwrap_or_0(self.iter.next_back());
ch = utf8_first_byte!(z, 2);
if utf8_is_cont_byte!(z) {
let y = unwrap_or_0(self.iter.next_back());
ch = utf8_first_byte!(y, 3);
if utf8_is_cont_byte!(y) {
let x = unwrap_or_0(self.iter.next_back());
ch = utf8_first_byte!(x, 4);
ch = utf8_acc_cont_byte!(ch, y);
}
ch = utf8_acc_cont_byte!(ch, z);
}
ch = utf8_acc_cont_byte!(ch, w);
// str invariant says `ch` is a valid Unicode Scalar Value
unsafe {
Some(mem::transmute(ch))
}
}
}
/// External iterator for a string's characters and their byte offsets.
/// Use with the `std::iter` module.
#[deriving(Clone)]
pub struct CharIndices<'a> {
front_offset: uint,
iter: Chars<'a>,
}
impl<'a> Iterator<(uint, char)> for CharIndices<'a> {
#[inline]
fn next(&mut self) -> Option<(uint, char)> {
let (pre_len, _) = self.iter.iter.size_hint();
match self.iter.next() {
None => None,
Some(ch) => {
let index = self.front_offset;
let (len, _) = self.iter.iter.size_hint();
self.front_offset += pre_len - len;
Some((index, ch))
}
}
}
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator<(uint, char)> for CharIndices<'a> {
#[inline]
fn next_back(&mut self) -> Option<(uint, char)> {
match self.iter.next_back() {
None => None,
Some(ch) => {
let (len, _) = self.iter.iter.size_hint();
let index = self.front_offset + len;
Some((index, ch))
}
}
}
}
/// External iterator for a string's bytes.
/// Use with the `std::iter` module.
///
/// Created with `StrExt::bytes`
#[stable]
#[deriving(Clone)]
pub struct Bytes<'a>(Map<&'a u8, u8, slice::Iter<'a, u8>, BytesDeref>);
delegate_iter!{exact u8 in Bytes<'a>}
/// A temporary fn new type that ensures that the `Bytes` iterator
/// is cloneable.
#[deriving(Copy, Clone)]
struct BytesDeref;
impl<'a> Fn(&'a u8) -> u8 for BytesDeref {
#[inline]
extern "rust-call" fn call(&self, (ptr,): (&'a u8,)) -> u8 {
*ptr
}
}
/// An iterator over the substrings of a string, separated by `sep`.
#[deriving(Clone)]
#[deprecated = "Type is now named `Split` or `SplitTerminator`"]
pub struct CharSplits<'a, Sep> {
/// The slice remaining to be iterated
string: &'a str,
sep: Sep,
/// Whether an empty string at the end is allowed
allow_trailing_empty: bool,
only_ascii: bool,
finished: bool,
}
/// An iterator over the substrings of a string, separated by `sep`,
/// splitting at most `count` times.
#[deriving(Clone)]
#[deprecated = "Type is now named `SplitN` or `RSplitN`"]
pub struct CharSplitsN<'a, Sep> {
iter: CharSplits<'a, Sep>,
/// The number of splits remaining
count: uint,
invert: bool,
}
/// An iterator over the lines of a string, separated by `\n`.
#[stable]
pub struct Lines<'a> {
inner: CharSplits<'a, char>,
}
/// An iterator over the lines of a string, separated by either `\n` or (`\r\n`).
#[stable]
pub struct LinesAny<'a> {
inner: Map<&'a str, &'a str, Lines<'a>, fn(&str) -> &str>,
}
impl<'a, Sep> CharSplits<'a, Sep> {
#[inline]
fn get_end(&mut self) -> Option<&'a str> {
if !self.finished && (self.allow_trailing_empty || self.string.len() > 0) {
self.finished = true;
Some(self.string)
} else {
None
}
}
}
impl<'a, Sep: CharEq> Iterator<&'a str> for CharSplits<'a, Sep> {
#[inline]
fn next(&mut self) -> Option<&'a str> {
if self.finished { return None }
let mut next_split = None;
if self.only_ascii {
for (idx, byte) in self.string.bytes().enumerate() {
if self.sep.matches(byte as char) && byte < 128u8 {
next_split = Some((idx, idx + 1));
break;
}
}
} else {
for (idx, ch) in self.string.char_indices() {
if self.sep.matches(ch) {
next_split = Some((idx, self.string.char_range_at(idx).next));
break;
}
}
}
match next_split {
Some((a, b)) => unsafe {
let elt = self.string.slice_unchecked(0, a);
self.string = self.string.slice_unchecked(b, self.string.len());
Some(elt)
},
None => self.get_end(),
}
}
}
impl<'a, Sep: CharEq> DoubleEndedIterator<&'a str>
for CharSplits<'a, Sep> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> {
if self.finished { return None }
if !self.allow_trailing_empty {
self.allow_trailing_empty = true;
match self.next_back() {
Some(elt) if !elt.is_empty() => return Some(elt),
_ => if self.finished { return None }
}
}
let len = self.string.len();
let mut next_split = None;
if self.only_ascii {
for (idx, byte) in self.string.bytes().enumerate().rev() {
if self.sep.matches(byte as char) && byte < 128u8 {
next_split = Some((idx, idx + 1));
break;
}
}
} else {
for (idx, ch) in self.string.char_indices().rev() {
if self.sep.matches(ch) {
next_split = Some((idx, self.string.char_range_at(idx).next));
break;
}
}
}
match next_split {
Some((a, b)) => unsafe {
let elt = self.string.slice_unchecked(b, len);
self.string = self.string.slice_unchecked(0, a);
Some(elt)
},
None => { self.finished = true; Some(self.string) }
}
}
}
impl<'a, Sep: CharEq> Iterator<&'a str> for CharSplitsN<'a, Sep> {
#[inline]
fn next(&mut self) -> Option<&'a str> {
if self.count != 0 {
self.count -= 1;
if self.invert { self.iter.next_back() } else { self.iter.next() }
} else {
self.iter.get_end()
}
}
}
/// The internal state of an iterator that searches for matches of a substring
/// within a larger string using naive search
#[deriving(Clone)]
struct NaiveSearcher {
position: uint
}
impl NaiveSearcher {
fn new() -> NaiveSearcher {
NaiveSearcher { position: 0 }
}
fn next(&mut self, haystack: &[u8], needle: &[u8]) -> Option<(uint, uint)> {
while self.position + needle.len() <= haystack.len() {
if haystack[self.position .. self.position + needle.len()] == needle {
let match_pos = self.position;
self.position += needle.len(); // add 1 for all matches
return Some((match_pos, match_pos + needle.len()));
} else {
self.position += 1;
}
}
None
}
}
/// The internal state of an iterator that searches for matches of a substring
/// within a larger string using two-way search
#[deriving(Clone)]
struct TwoWaySearcher {
// constants
crit_pos: uint,
period: uint,
byteset: u64,
// variables
position: uint,
memory: uint
}
/*
This is the Two-Way search algorithm, which was introduced in the paper:
Crochemore, M., Perrin, D., 1991, Two-way string-matching, Journal of the ACM 38(3):651-675.
Here's some background information.
A *word* is a string of symbols. The *length* of a word should be a familiar
notion, and here we denote it for any word x by |x|.
(We also allow for the possibility of the *empty word*, a word of length zero).
If x is any non-empty word, then an integer p with 0 < p <= |x| is said to be a
*period* for x iff for all i with 0 <= i <= |x| - p - 1, we have x[i] == x[i+p].
For example, both 1 and 2 are periods for the string "aa". As another example,
the only period of the string "abcd" is 4.
We denote by period(x) the *smallest* period of x (provided that x is non-empty).
This is always well-defined since every non-empty word x has at least one period,
|x|. We sometimes call this *the period* of x.
If u, v and x are words such that x = uv, where uv is the concatenation of u and
v, then we say that (u, v) is a *factorization* of x.
Let (u, v) be a factorization for a word x. Then if w is a non-empty word such
that both of the following hold
- either w is a suffix of u or u is a suffix of w
- either w is a prefix of v or v is a prefix of w
then w is said to be a *repetition* for the factorization (u, v).
Just to unpack this, there are four possibilities here. Let w = "abc". Then we
might have:
- w is a suffix of u and w is a prefix of v. ex: ("lolabc", "abcde")
- w is a suffix of u and v is a prefix of w. ex: ("lolabc", "ab")
- u is a suffix of w and w is a prefix of v. ex: ("bc", "abchi")
- u is a suffix of w and v is a prefix of w. ex: ("bc", "a")
Note that the word vu is a repetition for any factorization (u,v) of x = uv,
so every factorization has at least one repetition.
If x is a string and (u, v) is a factorization for x, then a *local period* for
(u, v) is an integer r such that there is some word w such that |w| = r and w is
a repetition for (u, v).
We denote by local_period(u, v) the smallest local period of (u, v). We sometimes
call this *the local period* of (u, v). Provided that x = uv is non-empty, this
is well-defined (because each non-empty word has at least one factorization, as
noted above).
It can be proven that the following is an equivalent definition of a local period
for a factorization (u, v): any positive integer r such that x[i] == x[i+r] for
all i such that |u| - r <= i <= |u| - 1 and such that both x[i] and x[i+r] are
defined. (i.e. i > 0 and i + r < |x|).
Using the above reformulation, it is easy to prove that
1 <= local_period(u, v) <= period(uv)
A factorization (u, v) of x such that local_period(u,v) = period(x) is called a
*critical factorization*.
The algorithm hinges on the following theorem, which is stated without proof:
**Critical Factorization Theorem** Any word x has at least one critical
factorization (u, v) such that |u| < period(x).
The purpose of maximal_suffix is to find such a critical factorization.
*/
impl TwoWaySearcher {
fn new(needle: &[u8]) -> TwoWaySearcher {
let (crit_pos1, period1) = TwoWaySearcher::maximal_suffix(needle, false);
let (crit_pos2, period2) = TwoWaySearcher::maximal_suffix(needle, true);
let crit_pos;
let period;
if crit_pos1 > crit_pos2 {
crit_pos = crit_pos1;
period = period1;
} else {
crit_pos = crit_pos2;
period = period2;
}
// This isn't in the original algorithm, as far as I'm aware.
let byteset = needle.iter()
.fold(0, |a, &b| (1 << ((b & 0x3f) as uint)) | a);
// A particularly readable explanation of what's going on here can be found
// in Crochemore and Rytter's book "Text Algorithms", ch 13. Specifically
// see the code for "Algorithm CP" on p. 323.
//
// What's going on is we have some critical factorization (u, v) of the
// needle, and we want to determine whether u is a suffix of
// v[..period]. If it is, we use "Algorithm CP1". Otherwise we use
// "Algorithm CP2", which is optimized for when the period of the needle
// is large.
if needle[..crit_pos] == needle[period.. period + crit_pos] {
TwoWaySearcher {
crit_pos: crit_pos,
period: period,
byteset: byteset,
position: 0,
memory: 0
}
} else {
TwoWaySearcher {
crit_pos: crit_pos,
period: cmp::max(crit_pos, needle.len() - crit_pos) + 1,
byteset: byteset,
position: 0,
memory: uint::MAX // Dummy value to signify that the period is long
}
}
}
// One of the main ideas of Two-Way is that we factorize the needle into
// two halves, (u, v), and begin trying to find v in the haystack by scanning
// left to right. If v matches, we try to match u by scanning right to left.
// How far we can jump when we encounter a mismatch is all based on the fact
// that (u, v) is a critical factorization for the needle.
#[inline]
fn next(&mut self, haystack: &[u8], needle: &[u8], long_period: bool) -> Option<(uint, uint)> {
'search: loop {
// Check that we have room to search in
if self.position + needle.len() > haystack.len() {
return None;
}
// Quickly skip by large portions unrelated to our substring
if (self.byteset >>
((haystack[self.position + needle.len() - 1] & 0x3f)
as uint)) & 1 == 0 {
self.position += needle.len();
if !long_period {
self.memory = 0;
}
continue 'search;
}
// See if the right part of the needle matches
let start = if long_period { self.crit_pos }
else { cmp::max(self.crit_pos, self.memory) };
for i in range(start, needle.len()) {
if needle[i] != haystack[self.position + i] {
self.position += i - self.crit_pos + 1;
if !long_period {
self.memory = 0;
}
continue 'search;
}
}
// See if the left part of the needle matches
let start = if long_period { 0 } else { self.memory };
for i in range(start, self.crit_pos).rev() {
if needle[i] != haystack[self.position + i] {
self.position += self.period;
if !long_period {
self.memory = needle.len() - self.period;
}
continue 'search;
}
}
// We have found a match!
let match_pos = self.position;
self.position += needle.len(); // add self.period for all matches
if !long_period {
self.memory = 0; // set to needle.len() - self.period for all matches
}
return Some((match_pos, match_pos + needle.len()));
}
}
// Computes a critical factorization (u, v) of `arr`.
// Specifically, returns (i, p), where i is the starting index of v in some
// critical factorization (u, v) and p = period(v)
#[inline]
fn maximal_suffix(arr: &[u8], reversed: bool) -> (uint, uint) {
let mut left = -1; // Corresponds to i in the paper
let mut right = 0; // Corresponds to j in the paper
let mut offset = 1; // Corresponds to k in the paper
let mut period = 1; // Corresponds to p in the paper
while right + offset < arr.len() {
let a;
let b;
if reversed {
a = arr[left + offset];
b = arr[right + offset];
} else {
a = arr[right + offset];
b = arr[left + offset];
}
if a < b {
// Suffix is smaller, period is entire prefix so far.
right += offset;
offset = 1;
period = right - left;
} else if a == b {
// Advance through repetition of the current period.
if offset == period {
right += offset;
offset = 1;
} else {
offset += 1;
}
} else {
// Suffix is larger, start over from current location.
left = right;
right += 1;
offset = 1;
period = 1;
}
}
(left + 1, period)
}
}
/// The internal state of an iterator that searches for matches of a substring
/// within a larger string using a dynamically chosen search algorithm
#[deriving(Clone)]
enum Searcher {
Naive(NaiveSearcher),
TwoWay(TwoWaySearcher),
TwoWayLong(TwoWaySearcher)
}
impl Searcher {
fn new(haystack: &[u8], needle: &[u8]) -> Searcher {
// FIXME: Tune this.
// FIXME(#16715): This unsigned integer addition will probably not
// overflow because that would mean that the memory almost solely
// consists of the needle. Needs #16715 to be formally fixed.
if needle.len() + 20 > haystack.len() {
Naive(NaiveSearcher::new())
} else {
let searcher = TwoWaySearcher::new(needle);
if searcher.memory == uint::MAX { // If the period is long
TwoWayLong(searcher)
} else {
TwoWay(searcher)
}
}
}
}
/// An iterator over the start and end indices of the matches of a
/// substring within a larger string
#[deriving(Clone)]
pub struct MatchIndices<'a> {
// constants
haystack: &'a str,
needle: &'a str,
searcher: Searcher
}
/// An iterator over the substrings of a string separated by a given
/// search string
#[deriving(Clone)]
#[unstable = "Type might get removed"]
pub struct SplitStr<'a> {
it: MatchIndices<'a>,
last_end: uint,
finished: bool
}
/// Deprecated
#[deprecated = "Type is now named `SplitStr`"]
pub type StrSplits<'a> = SplitStr<'a>;
impl<'a> Iterator<(uint, uint)> for MatchIndices<'a> {
#[inline]
fn next(&mut self) -> Option<(uint, uint)> {
match self.searcher {
Naive(ref mut searcher)
=> searcher.next(self.haystack.as_bytes(), self.needle.as_bytes()),
TwoWay(ref mut searcher)
=> searcher.next(self.haystack.as_bytes(), self.needle.as_bytes(), false),
TwoWayLong(ref mut searcher)
=> searcher.next(self.haystack.as_bytes(), self.needle.as_bytes(), true)
}
}
}
impl<'a> Iterator<&'a str> for SplitStr<'a> {
#[inline]
fn next(&mut self) -> Option<&'a str> {
if self.finished { return None; }
match self.it.next() {
Some((from, to)) => {
let ret = Some(self.it.haystack.slice(self.last_end, from));
self.last_end = to;
ret
}
None => {
self.finished = true;
Some(self.it.haystack.slice(self.last_end, self.it.haystack.len()))
}
}
}
}
/*
Section: Comparing strings
*/
// share the implementation of the lang-item vs. non-lang-item
// eq_slice.
/// NOTE: This function is (ab)used in rustc::middle::trans::_match
/// to compare &[u8] byte slices that are not necessarily valid UTF-8.
#[inline]
fn eq_slice_(a: &str, b: &str) -> bool {
#[allow(improper_ctypes)]
extern { fn memcmp(s1: *const i8, s2: *const i8, n: uint) -> i32; }
a.len() == b.len() && unsafe {
memcmp(a.as_ptr() as *const i8,
b.as_ptr() as *const i8,
a.len()) == 0
}
}
/// Bytewise slice equality
/// NOTE: This function is (ab)used in rustc::middle::trans::_match
/// to compare &[u8] byte slices that are not necessarily valid UTF-8.
#[lang="str_eq"]
#[inline]
fn eq_slice(a: &str, b: &str) -> bool {
eq_slice_(a, b)
}
/*
Section: Misc
*/
/// Walk through `iter` checking that it's a valid UTF-8 sequence,
/// returning `true` in that case, or, if it is invalid, `false` with
/// `iter` reset such that it is pointing at the first byte in the
/// invalid sequence.
#[inline(always)]
fn run_utf8_validation_iterator(iter: &mut slice::Iter<u8>)
-> Result<(), Utf8Error> {
let whole = iter.as_slice();
loop {
// save the current thing we're pointing at.
let old = *iter;
// restore the iterator we had at the start of this codepoint.
macro_rules! err (() => { {
*iter = old;
return Err(Utf8Error::InvalidByte(whole.len() - iter.as_slice().len()))
} });
macro_rules! next ( () => {
match iter.next() {
Some(a) => *a,
// we needed data, but there was none: error!
None => return Err(Utf8Error::TooShort),
}
});
let first = match iter.next() {
Some(&b) => b,
// we're at the end of the iterator and a codepoint
// boundary at the same time, so this string is valid.
None => return Ok(())
};
// ASCII characters are always valid, so only large
// bytes need more examination.
if first >= 128 {
let w = UTF8_CHAR_WIDTH[first as uint] as uint;
let second = next!();
// 2-byte encoding is for codepoints \u{0080} to \u{07ff}
// first C2 80 last DF BF
// 3-byte encoding is for codepoints \u{0800} to \u{ffff}
// first E0 A0 80 last EF BF BF
// excluding surrogates codepoints \u{d800} to \u{dfff}
// ED A0 80 to ED BF BF
// 4-byte encoding is for codepoints \u{1000}0 to \u{10ff}ff
// first F0 90 80 80 last F4 8F BF BF
//
// Use the UTF-8 syntax from the RFC
//
// https://tools.ietf.org/html/rfc3629
// UTF8-1 = %x00-7F
// UTF8-2 = %xC2-DF UTF8-tail
// UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
// %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
// UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
// %xF4 %x80-8F 2( UTF8-tail )
match w {
2 => if second & !CONT_MASK != TAG_CONT_U8 {err!()},
3 => {
match (first, second, next!() & !CONT_MASK) {
(0xE0 , 0xA0 ... 0xBF, TAG_CONT_U8) |
(0xE1 ... 0xEC, 0x80 ... 0xBF, TAG_CONT_U8) |
(0xED , 0x80 ... 0x9F, TAG_CONT_U8) |
(0xEE ... 0xEF, 0x80 ... 0xBF, TAG_CONT_U8) => {}
_ => err!()
}
}
4 => {
match (first, second, next!() & !CONT_MASK, next!() & !CONT_MASK) {
(0xF0 , 0x90 ... 0xBF, TAG_CONT_U8, TAG_CONT_U8) |
(0xF1 ... 0xF3, 0x80 ... 0xBF, TAG_CONT_U8, TAG_CONT_U8) |
(0xF4 , 0x80 ... 0x8F, TAG_CONT_U8, TAG_CONT_U8) => {}
_ => err!()
}
}
_ => err!()
}
}
}
}
/// Determines if a vector of bytes contains valid UTF-8.
#[deprecated = "call from_utf8 instead"]
pub fn is_utf8(v: &[u8]) -> bool {
run_utf8_validation_iterator(&mut v.iter()).is_ok()
}
/// Deprecated function
#[deprecated = "this function will be removed"]
pub fn truncate_utf16_at_nul<'a>(v: &'a [u16]) -> &'a [u16] {
match v.iter().position(|c| *c == 0) {
// don't include the 0
Some(i) => v[..i],
None => v
}
}
// https://tools.ietf.org/html/rfc3629
static UTF8_CHAR_WIDTH: [u8, ..256] = [
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x1F
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x3F
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x5F
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x7F
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 0x9F
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 0xBF
0,0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // 0xDF
3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, // 0xEF
4,4,4,4,4,0,0,0,0,0,0,0,0,0,0,0, // 0xFF
];
/// Given a first byte, determine how many bytes are in this UTF-8 character
#[inline]
#[deprecated = "this function has moved to libunicode"]
pub fn utf8_char_width(b: u8) -> uint {
return UTF8_CHAR_WIDTH[b as uint] as uint;
}
/// Struct that contains a `char` and the index of the first byte of
/// the next `char` in a string. This can be used as a data structure
/// for iterating over the UTF-8 bytes of a string.
#[deriving(Copy)]
#[unstable = "naming is uncertain with container conventions"]
pub struct CharRange {
/// Current `char`
pub ch: char,
/// Index of the first byte of the next `char`
pub next: uint,
}
/// Mask of the value bits of a continuation byte
const CONT_MASK: u8 = 0b0011_1111u8;
/// Value of the tag bits (tag mask is !CONT_MASK) of a continuation byte
const TAG_CONT_U8: u8 = 0b1000_0000u8;
/// Unsafe operations
#[deprecated]
pub mod raw {
use ptr::PtrExt;
use raw::Slice;
use slice::SliceExt;
use str::StrExt;
/// Converts a slice of bytes to a string slice without checking
/// that the string contains valid UTF-8.
#[deprecated = "renamed to str::from_utf8_unchecked"]
pub unsafe fn from_utf8<'a>(v: &'a [u8]) -> &'a str {
super::from_utf8_unchecked(v)
}
/// Form a slice from a C string. Unsafe because the caller must ensure the
/// C string has the static lifetime, or else the return value may be
/// invalidated later.
#[deprecated = "renamed to str::from_c_str"]
pub unsafe fn c_str_to_static_slice(s: *const i8) -> &'static str {
let s = s as *const u8;
let mut curr = s;
let mut len = 0u;
while *curr != 0u8 {
len += 1u;
curr = s.offset(len as int);
}
let v = Slice { data: s, len: len };
super::from_utf8(::mem::transmute(v)).unwrap()
}
/// Takes a bytewise (not UTF-8) slice from a string.
///
/// Returns the substring from [`begin`..`end`).
///
/// # Panics
///
/// If begin is greater than end.
/// If end is greater than the length of the string.
#[inline]
#[deprecated = "call the slice_unchecked method instead"]
pub unsafe fn slice_bytes<'a>(s: &'a str, begin: uint, end: uint) -> &'a str {
assert!(begin <= end);
assert!(end <= s.len());
s.slice_unchecked(begin, end)
}
/// Takes a bytewise (not UTF-8) slice from a string.
///
/// Returns the substring from [`begin`..`end`).
///
/// Caller must check slice boundaries!
#[inline]
#[deprecated = "this has moved to a method on `str` directly"]
pub unsafe fn slice_unchecked<'a>(s: &'a str, begin: uint, end: uint) -> &'a str {
s.slice_unchecked(begin, end)
}
}
/*
Section: Trait implementations
*/
#[allow(missing_docs)]
pub mod traits {
use cmp::{Ordering, Ord, PartialEq, PartialOrd, Equiv, Eq};
use cmp::Ordering::{Less, Equal, Greater};
use iter::IteratorExt;
use option::Option;
use option::Option::Some;
use ops;
use str::{Str, StrExt, eq_slice};
impl Ord for str {
#[inline]
fn cmp(&self, other: &str) -> Ordering {
for (s_b, o_b) in self.bytes().zip(other.bytes()) {
match s_b.cmp(&o_b) {
Greater => return Greater,
Less => return Less,
Equal => ()
}
}
self.len().cmp(&other.len())
}
}
impl PartialEq for str {
#[inline]
fn eq(&self, other: &str) -> bool {
eq_slice(self, other)
}
#[inline]
fn ne(&self, other: &str) -> bool { !(*self).eq(other) }
}
impl Eq for str {}
impl PartialOrd for str {
#[inline]
fn partial_cmp(&self, other: &str) -> Option<Ordering> {
Some(self.cmp(other))
}
}
#[allow(deprecated)]
#[deprecated = "Use overloaded `core::cmp::PartialEq`"]
impl<S: Str> Equiv<S> for str {
#[inline]
fn equiv(&self, other: &S) -> bool { eq_slice(self, other.as_slice()) }
}
impl ops::Slice<uint, str> for str {
#[inline]
fn as_slice_<'a>(&'a self) -> &'a str {
self
}
#[inline]
fn slice_from_or_fail<'a>(&'a self, from: &uint) -> &'a str {
self.slice_from(*from)
}
#[inline]
fn slice_to_or_fail<'a>(&'a self, to: &uint) -> &'a str {
self.slice_to(*to)
}
#[inline]
fn slice_or_fail<'a>(&'a self, from: &uint, to: &uint) -> &'a str {
self.slice(*from, *to)
}
}
}
/// Any string that can be represented as a slice
#[unstable = "Instead of taking this bound generically, this trait will be \
replaced with one of slicing syntax, deref coercions, or \
a more generic conversion trait"]
pub trait Str for Sized? {
/// Work with `self` as a slice.
fn as_slice<'a>(&'a self) -> &'a str;
}
#[allow(deprecated)]
impl Str for str {
#[inline]
fn as_slice<'a>(&'a self) -> &'a str { self }
}
#[allow(deprecated)]
impl<'a, Sized? S> Str for &'a S where S: Str {
#[inline]
fn as_slice(&self) -> &str { Str::as_slice(*self) }
}
/// Return type of `StrExt::split`
#[deriving(Clone)]
#[stable]
pub struct Split<'a, P>(CharSplits<'a, P>);
delegate_iter!{pattern &'a str in Split<'a, P>}
/// Return type of `StrExt::split_terminator`
#[deriving(Clone)]
#[unstable = "might get removed in favour of a constructor method on Split"]
pub struct SplitTerminator<'a, P>(CharSplits<'a, P>);
delegate_iter!{pattern &'a str in SplitTerminator<'a, P>}
/// Return type of `StrExt::splitn`
#[deriving(Clone)]
#[stable]
pub struct SplitN<'a, P>(CharSplitsN<'a, P>);
delegate_iter!{pattern forward &'a str in SplitN<'a, P>}
/// Return type of `StrExt::rsplitn`
#[deriving(Clone)]
#[stable]
pub struct RSplitN<'a, P>(CharSplitsN<'a, P>);
delegate_iter!{pattern forward &'a str in RSplitN<'a, P>}
/// Methods for string slices
#[allow(missing_docs)]
pub trait StrExt for Sized? {
// NB there are no docs here are they're all located on the StrExt trait in
// libcollections, not here.
fn contains(&self, pat: &str) -> bool;
fn contains_char<P: CharEq>(&self, pat: P) -> bool;
fn chars<'a>(&'a self) -> Chars<'a>;
fn bytes<'a>(&'a self) -> Bytes<'a>;
fn char_indices<'a>(&'a self) -> CharIndices<'a>;
fn split<'a, P: CharEq>(&'a self, pat: P) -> Split<'a, P>;
fn splitn<'a, P: CharEq>(&'a self, count: uint, pat: P) -> SplitN<'a, P>;
fn split_terminator<'a, P: CharEq>(&'a self, pat: P) -> SplitTerminator<'a, P>;
fn rsplitn<'a, P: CharEq>(&'a self, count: uint, pat: P) -> RSplitN<'a, P>;
fn match_indices<'a>(&'a self, sep: &'a str) -> MatchIndices<'a>;
fn split_str<'a>(&'a self, pat: &'a str) -> SplitStr<'a>;
fn lines<'a>(&'a self) -> Lines<'a>;
fn lines_any<'a>(&'a self) -> LinesAny<'a>;
fn char_len(&self) -> uint;
fn slice<'a>(&'a self, begin: uint, end: uint) -> &'a str;
fn slice_from<'a>(&'a self, begin: uint) -> &'a str;
fn slice_to<'a>(&'a self, end: uint) -> &'a str;
fn slice_chars<'a>(&'a self, begin: uint, end: uint) -> &'a str;
unsafe fn slice_unchecked<'a>(&'a self, begin: uint, end: uint) -> &'a str;
fn starts_with(&self, pat: &str) -> bool;
fn ends_with(&self, pat: &str) -> bool;
fn trim_matches<'a, P: CharEq>(&'a self, pat: P) -> &'a str;
fn trim_left_matches<'a, P: CharEq>(&'a self, pat: P) -> &'a str;
fn trim_right_matches<'a, P: CharEq>(&'a self, pat: P) -> &'a str;
fn is_char_boundary(&self, index: uint) -> bool;
fn char_range_at(&self, start: uint) -> CharRange;
fn char_range_at_reverse(&self, start: uint) -> CharRange;
fn char_at(&self, i: uint) -> char;
fn char_at_reverse(&self, i: uint) -> char;
fn as_bytes<'a>(&'a self) -> &'a [u8];
fn find<P: CharEq>(&self, pat: P) -> Option<uint>;
fn rfind<P: CharEq>(&self, pat: P) -> Option<uint>;
fn find_str(&self, pat: &str) -> Option<uint>;
fn slice_shift_char<'a>(&'a self) -> Option<(char, &'a str)>;
fn subslice_offset(&self, inner: &str) -> uint;
fn as_ptr(&self) -> *const u8;
fn len(&self) -> uint;
fn is_empty(&self) -> bool;
}
#[inline(never)]
fn slice_error_fail(s: &str, begin: uint, end: uint) -> ! {
assert!(begin <= end);
panic!("index {} and/or {} in `{}` do not lie on character boundary",
begin, end, s);
}
impl StrExt for str {
#[inline]
fn contains(&self, needle: &str) -> bool {
self.find_str(needle).is_some()
}
#[inline]
fn contains_char<P: CharEq>(&self, pat: P) -> bool {
self.find(pat).is_some()
}
#[inline]
fn chars(&self) -> Chars {
Chars{iter: self.as_bytes().iter()}
}
#[inline]
fn bytes(&self) -> Bytes {
Bytes(self.as_bytes().iter().map(BytesDeref))
}
#[inline]
fn char_indices(&self) -> CharIndices {
CharIndices { front_offset: 0, iter: self.chars() }
}
#[inline]
#[allow(deprecated)] // For using CharSplits
fn split<P: CharEq>(&self, pat: P) -> Split<P> {
Split(CharSplits {
string: self,
only_ascii: pat.only_ascii(),
sep: pat,
allow_trailing_empty: true,
finished: false,
})
}
#[inline]
#[allow(deprecated)] // For using CharSplitsN
fn splitn<P: CharEq>(&self, count: uint, pat: P) -> SplitN<P> {
SplitN(CharSplitsN {
iter: self.split(pat).0,
count: count,
invert: false,
})
}
#[inline]
#[allow(deprecated)] // For using CharSplits
fn split_terminator<P: CharEq>(&self, pat: P) -> SplitTerminator<P> {
SplitTerminator(CharSplits {
allow_trailing_empty: false,
..self.split(pat).0
})
}
#[inline]
#[allow(deprecated)] // For using CharSplitsN
fn rsplitn<P: CharEq>(&self, count: uint, pat: P) -> RSplitN<P> {
RSplitN(CharSplitsN {
iter: self.split(pat).0,
count: count,
invert: true,
})
}
#[inline]
fn match_indices<'a>(&'a self, sep: &'a str) -> MatchIndices<'a> {
assert!(!sep.is_empty());
MatchIndices {
haystack: self,
needle: sep,
searcher: Searcher::new(self.as_bytes(), sep.as_bytes())
}
}
#[inline]
fn split_str<'a>(&'a self, sep: &'a str) -> SplitStr<'a> {
SplitStr {
it: self.match_indices(sep),
last_end: 0,
finished: false
}
}
#[inline]
fn lines(&self) -> Lines {
Lines { inner: self.split_terminator('\n').0 }
}
fn lines_any(&self) -> LinesAny {
fn f(line: &str) -> &str {
let l = line.len();
if l > 0 && line.as_bytes()[l - 1] == b'\r' { line.slice(0, l - 1) }
else { line }
}
let f: fn(&str) -> &str = f; // coerce to fn pointer
LinesAny { inner: self.lines().map(f) }
}
#[inline]
fn char_len(&self) -> uint { self.chars().count() }
#[inline]
fn slice(&self, begin: uint, end: uint) -> &str {
// is_char_boundary checks that the index is in [0, .len()]
if begin <= end &&
self.is_char_boundary(begin) &&
self.is_char_boundary(end) {
unsafe { self.slice_unchecked(begin, end) }
} else {
slice_error_fail(self, begin, end)
}
}
#[inline]
fn slice_from(&self, begin: uint) -> &str {
// is_char_boundary checks that the index is in [0, .len()]
if self.is_char_boundary(begin) {
unsafe { self.slice_unchecked(begin, self.len()) }
} else {
slice_error_fail(self, begin, self.len())
}
}
#[inline]
fn slice_to(&self, end: uint) -> &str {
// is_char_boundary checks that the index is in [0, .len()]
if self.is_char_boundary(end) {
unsafe { self.slice_unchecked(0, end) }
} else {
slice_error_fail(self, 0, end)
}
}
fn slice_chars(&self, begin: uint, end: uint) -> &str {
assert!(begin <= end);
let mut count = 0;
let mut begin_byte = None;
let mut end_byte = None;
// This could be even more efficient by not decoding,
// only finding the char boundaries
for (idx, _) in self.char_indices() {
if count == begin { begin_byte = Some(idx); }
if count == end { end_byte = Some(idx); break; }
count += 1;
}
if begin_byte.is_none() && count == begin { begin_byte = Some(self.len()) }
if end_byte.is_none() && count == end { end_byte = Some(self.len()) }
match (begin_byte, end_byte) {
(None, _) => panic!("slice_chars: `begin` is beyond end of string"),
(_, None) => panic!("slice_chars: `end` is beyond end of string"),
(Some(a), Some(b)) => unsafe { self.slice_unchecked(a, b) }
}
}
#[inline]
unsafe fn slice_unchecked(&self, begin: uint, end: uint) -> &str {
mem::transmute(Slice {
data: self.as_ptr().offset(begin as int),
len: end - begin,
})
}
#[inline]
fn starts_with(&self, needle: &str) -> bool {
let n = needle.len();
self.len() >= n && needle.as_bytes() == self.as_bytes()[..n]
}
#[inline]
fn ends_with(&self, needle: &str) -> bool {
let (m, n) = (self.len(), needle.len());
m >= n && needle.as_bytes() == self.as_bytes()[m-n..]
}
#[inline]
fn trim_matches<P: CharEq>(&self, mut pat: P) -> &str {
let cur = match self.find(|&mut: c: char| !pat.matches(c)) {
None => "",
Some(i) => unsafe { self.slice_unchecked(i, self.len()) }
};
match cur.rfind(|&mut: c: char| !pat.matches(c)) {
None => "",
Some(i) => {
let right = cur.char_range_at(i).next;
unsafe { cur.slice_unchecked(0, right) }
}
}
}
#[inline]
fn trim_left_matches<P: CharEq>(&self, mut pat: P) -> &str {
match self.find(|&mut: c: char| !pat.matches(c)) {
None => "",
Some(first) => unsafe { self.slice_unchecked(first, self.len()) }
}
}
#[inline]
fn trim_right_matches<P: CharEq>(&self, mut pat: P) -> &str {
match self.rfind(|&mut: c: char| !pat.matches(c)) {
None => "",
Some(last) => {
let next = self.char_range_at(last).next;
unsafe { self.slice_unchecked(0u, next) }
}
}
}
#[inline]
fn is_char_boundary(&self, index: uint) -> bool {
if index == self.len() { return true; }
match self.as_bytes().get(index) {
None => false,
Some(&b) => b < 128u8 || b >= 192u8,
}
}
#[inline]
fn char_range_at(&self, i: uint) -> CharRange {
if self.as_bytes()[i] < 128u8 {
return CharRange {ch: self.as_bytes()[i] as char, next: i + 1 };
}
// Multibyte case is a fn to allow char_range_at to inline cleanly
fn multibyte_char_range_at(s: &str, i: uint) -> CharRange {
let mut val = s.as_bytes()[i] as u32;
let w = UTF8_CHAR_WIDTH[val as uint] as uint;
assert!((w != 0));
val = utf8_first_byte!(val, w);
val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 1]);
if w > 2 { val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 2]); }
if w > 3 { val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 3]); }
return CharRange {ch: unsafe { mem::transmute(val) }, next: i + w};
}
return multibyte_char_range_at(self, i);
}
#[inline]
fn char_range_at_reverse(&self, start: uint) -> CharRange {
let mut prev = start;
prev = prev.saturating_sub(1);
if self.as_bytes()[prev] < 128 {
return CharRange{ch: self.as_bytes()[prev] as char, next: prev}
}
// Multibyte case is a fn to allow char_range_at_reverse to inline cleanly
fn multibyte_char_range_at_reverse(s: &str, mut i: uint) -> CharRange {
// while there is a previous byte == 10......
while i > 0 && s.as_bytes()[i] & !CONT_MASK == TAG_CONT_U8 {
i -= 1u;
}
let mut val = s.as_bytes()[i] as u32;
let w = UTF8_CHAR_WIDTH[val as uint] as uint;
assert!((w != 0));
val = utf8_first_byte!(val, w);
val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 1]);
if w > 2 { val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 2]); }
if w > 3 { val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 3]); }
return CharRange {ch: unsafe { mem::transmute(val) }, next: i};
}
return multibyte_char_range_at_reverse(self, prev);
}
#[inline]
fn char_at(&self, i: uint) -> char {
self.char_range_at(i).ch
}
#[inline]
fn char_at_reverse(&self, i: uint) -> char {
self.char_range_at_reverse(i).ch
}
#[inline]
fn as_bytes(&self) -> &[u8] {
unsafe { mem::transmute(self) }
}
fn find<P: CharEq>(&self, mut pat: P) -> Option<uint> {
if pat.only_ascii() {
self.bytes().position(|b| pat.matches(b as char))
} else {
for (index, c) in self.char_indices() {
if pat.matches(c) { return Some(index); }
}
None
}
}
fn rfind<P: CharEq>(&self, mut pat: P) -> Option<uint> {
if pat.only_ascii() {
self.bytes().rposition(|b| pat.matches(b as char))
} else {
for (index, c) in self.char_indices().rev() {
if pat.matches(c) { return Some(index); }
}
None
}
}
fn find_str(&self, needle: &str) -> Option<uint> {
if needle.is_empty() {
Some(0)
} else {
self.match_indices(needle)
.next()
.map(|(start, _end)| start)
}
}
#[inline]
fn slice_shift_char(&self) -> Option<(char, &str)> {
if self.is_empty() {
None
} else {
let CharRange {ch, next} = self.char_range_at(0u);
let next_s = unsafe { self.slice_unchecked(next, self.len()) };
Some((ch, next_s))
}
}
fn subslice_offset(&self, inner: &str) -> uint {
let a_start = self.as_ptr() as uint;
let a_end = a_start + self.len();
let b_start = inner.as_ptr() as uint;
let b_end = b_start + inner.len();
assert!(a_start <= b_start);
assert!(b_end <= a_end);
b_start - a_start
}
#[inline]
fn as_ptr(&self) -> *const u8 {
self.repr().data
}
#[inline]
fn len(&self) -> uint { self.repr().len }
#[inline]
fn is_empty(&self) -> bool { self.len() == 0 }
}
#[stable]
impl<'a> Default for &'a str {
#[stable]
fn default() -> &'a str { "" }
}
impl<'a> Iterator<&'a str> for Lines<'a> {
#[inline]
fn next(&mut self) -> Option<&'a str> { self.inner.next() }
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
}
impl<'a> DoubleEndedIterator<&'a str> for Lines<'a> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> { self.inner.next_back() }
}
impl<'a> Iterator<&'a str> for LinesAny<'a> {
#[inline]
fn next(&mut self) -> Option<&'a str> { self.inner.next() }
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) { self.inner.size_hint() }
}
impl<'a> DoubleEndedIterator<&'a str> for LinesAny<'a> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> { self.inner.next_back() }
}
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