// 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

//! Unicode string manipulation (`str` type)
//!
//! # Basic Usage
//!
//! Rust's string type is one of the core primitive types of the language. While
//! represented by the name `str`, the name `str` is not actually a valid type in
//! Rust. Each string must also be decorated with a pointer. `String` is used
//! for an owned string, so there is only one commonly-used `str` type in Rust:
//! `&str`.
//!
//! `&str` is the borrowed string type. This type of string can only be created
//! from other strings, unless it is a static string (see below). As the word
//! "borrowed" implies, this type of string is owned elsewhere, and this string
//! cannot be moved out of.
//!
//! As an example, here's some code that uses a string.
//!
//! ```rust
//! fn main() {
//!     let borrowed_string = "This string is borrowed with the 'static lifetime";
//! }
//! ```
//!
//! From the example above, you can see that Rust's string literals have the
//! `'static` lifetime. This is akin to C's concept of a static string.
//!
//! String literals are allocated statically in the rodata of the
//! executable/library. The string then has the type `&'static str` meaning that
//! the string is valid for the `'static` lifetime, otherwise known as the
//! lifetime of the entire program. As can be inferred from the type, these static
//! strings are not mutable.
//!
//! # Representation
//!
//! Rust's string type, `str`, is a sequence of unicode scalar values encoded as a
//! stream of UTF-8 bytes. All strings are guaranteed to be validly encoded UTF-8
//! sequences. Additionally, strings are not null-terminated and can contain null
//! bytes.
//!
//! The actual representation of strings have direct mappings to slices: `&str`
//! is the same as `&[u8]`.

#![doc(primitive = "str")]

use core::default::Default;
use core::fmt;
use core::cmp;
use core::iter::AdditiveIterator;
use core::mem;
use core::prelude::{Char, Clone, Collection, Eq, Equiv, ImmutableSlice};
use core::prelude::{Iterator, MutableSlice, None, Option, Ord, Ordering};
use core::prelude::{PartialEq, PartialOrd, Result, Slice, Some, Tuple2};
use core::prelude::{range};

use {Deque, MutableSeq};
use hash;
use ringbuf::RingBuf;
use string::String;
use unicode;
use vec::Vec;

pub use core::str::{from_utf8, CharEq, Chars, CharOffsets};
pub use core::str::{Bytes, CharSplits};
pub use core::str::{CharSplitsN, AnyLines, MatchIndices, StrSplits};
pub use core::str::{eq_slice, is_utf8, is_utf16, Utf16Items};
pub use core::str::{Utf16Item, ScalarValue, LoneSurrogate, utf16_items};
pub use core::str::{truncate_utf16_at_nul, utf8_char_width, CharRange};
pub use core::str::{Str, StrSlice};
pub use unicode::str::{UnicodeStrSlice, Words, Graphemes, GraphemeIndices};

/*
Section: Creating a string
*/

/// Deprecated. Replaced by `String::from_utf8`.
#[deprecated = "Replaced by `String::from_utf8`"]
pub fn from_utf8_owned(vv: Vec<u8>) -> Result<String, Vec<u8>> {
    String::from_utf8(vv)
}

/// Deprecated. Replaced by `String::from_byte`.
#[deprecated = "Replaced by String::from_byte"]
pub fn from_byte(b: u8) -> String {
    assert!(b < 128u8);
    String::from_char(1, b as char)
}

/// Deprecated. Use `String::from_char` or `char::to_string()` instead.
#[deprecated = "use String::from_char or char.to_string()"]
pub fn from_char(ch: char) -> String {
    String::from_char(1, ch)
}

/// Deprecated. Replaced by `String::from_chars`.
#[deprecated = "use String::from_chars instead"]
pub fn from_chars(chs: &[char]) -> String {
    chs.iter().map(|c| *c).collect()
}

/// Methods for vectors of strings.
pub trait StrVector {
    /// Concatenates a vector of strings.
    ///
    /// # Example
    ///
    /// ```rust
    /// let first = "Restaurant at the End of the".to_string();
    /// let second = " Universe".to_string();
    /// let string_vec = vec![first, second];
    /// assert_eq!(string_vec.concat(), "Restaurant at the End of the Universe".to_string());
    /// ```
    fn concat(&self) -> String;

    /// Concatenates a vector of strings, placing a given separator between each.
    ///
    /// # Example
    ///
    /// ```rust
    /// let first = "Roast".to_string();
    /// let second = "Sirloin Steak".to_string();
    /// let string_vec = vec![first, second];
    /// assert_eq!(string_vec.connect(", "), "Roast, Sirloin Steak".to_string());
    /// ```
    fn connect(&self, sep: &str) -> String;
}

impl<'a, S: Str> StrVector for &'a [S] {
    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.as_slice().len()).sum();

        let mut result = String::with_capacity(len);

        for s in self.iter() {
            result.push_str(s.as_slice())
        }

        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.as_slice().len()).sum();
        let mut result = String::with_capacity(len);
        let mut first = true;

        for s in self.iter() {
            if first {
                first = false;
            } else {
                result.push_str(sep);
            }
            result.push_str(s.as_slice());
        }
        result
    }
}

impl<'a, S: Str> StrVector for Vec<S> {
    #[inline]
    fn concat(&self) -> String {
        self.as_slice().concat()
    }

    #[inline]
    fn connect(&self, sep: &str) -> String {
        self.as_slice().connect(sep)
    }
}

/*
Section: Iterators
*/

// Helper functions used for Unicode normalization
fn canonical_sort(comb: &mut [(char, u8)]) {
    let len = comb.len();
    for i in range(0, len) {
        let mut swapped = false;
        for j in range(1, len-i) {
            let class_a = *comb[j-1].ref1();
            let class_b = *comb[j].ref1();
            if class_a != 0 && class_b != 0 && class_a > class_b {
                comb.swap(j-1, j);
                swapped = true;
            }
        }
        if !swapped { break; }
    }
}

#[deriving(Clone)]
enum DecompositionType {
    Canonical,
    Compatible
}

/// External iterator for a string's decomposition's characters.
/// Use with the `std::iter` module.
#[deriving(Clone)]
pub struct Decompositions<'a> {
    kind: DecompositionType,
    iter: Chars<'a>,
    buffer: Vec<(char, u8)>,
    sorted: bool
}

impl<'a> Iterator<char> for Decompositions<'a> {
    #[inline]
    fn next(&mut self) -> Option<char> {
        match self.buffer.as_slice().head() {
            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
        }

        let decomposer = match self.kind {
            Canonical => unicode::char::decompose_canonical,
            Compatible => unicode::char::decompose_compatible
        };

        if !self.sorted {
            for ch in self.iter {
                let buffer = &mut self.buffer;
                let sorted = &mut self.sorted;
                decomposer(ch, |d| {
                    let class = unicode::char::canonical_combining_class(d);
                    if class == 0 && !*sorted {
                        canonical_sort(buffer.as_mut_slice());
                        *sorted = true;
                    }
                    buffer.push((d, class));
                });
                if *sorted { break }
            }
        }

        if !self.sorted {
            canonical_sort(self.buffer.as_mut_slice());
            self.sorted = true;
        }

        match self.buffer.remove(0) {
            Some((c, 0)) => {
                self.sorted = false;
                Some(c)
            }
            Some((c, _)) => Some(c),
            None => None
        }
    }

    fn size_hint(&self) -> (uint, Option<uint>) {
        let (lower, _) = self.iter.size_hint();
        (lower, None)
    }
}

#[deriving(Clone)]
enum RecompositionState {
    Composing,
    Purging,
    Finished
}

/// External iterator for a string's recomposition's characters.
/// Use with the `std::iter` module.
#[deriving(Clone)]
pub struct Recompositions<'a> {
    iter: Decompositions<'a>,
    state: RecompositionState,
    buffer: RingBuf<char>,
    composee: Option<char>,
    last_ccc: Option<u8>
}

impl<'a> Iterator<char> for Recompositions<'a> {
    #[inline]
    fn next(&mut self) -> Option<char> {
        loop {
            match self.state {
                Composing => {
                    for ch in self.iter {
                        let ch_class = 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 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(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(ch);
                                    self.last_ccc = Some(ch_class);
                                    continue;
                                }
                                match unicode::char::compose(k, ch) {
                                    Some(r) => {
                                        self.composee = Some(r);
                                        continue;
                                    }
                                    None => {
                                        self.buffer.push(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
                    }
                }
            }
        }
    }
}

/// Replaces all occurrences of one string with another.
///
/// # Arguments
///
/// * s - The string containing substrings to replace
/// * from - The string to replace
/// * to - The replacement string
///
/// # Return value
///
/// The original string with all occurrences of `from` replaced with `to`.
///
/// # Example
///
/// ```rust
/// use std::str;
/// let string = "orange";
/// let new_string = str::replace(string, "or", "str");
/// assert_eq!(new_string.as_slice(), "strange");
/// ```
pub fn replace(s: &str, from: &str, to: &str) -> String {
    let mut result = String::new();
    let mut last_end = 0;
    for (start, end) in s.match_indices(from) {
        result.push_str(unsafe{raw::slice_bytes(s, last_end, start)});
        result.push_str(to);
        last_end = end;
    }
    result.push_str(unsafe{raw::slice_bytes(s, last_end, s.len())});
    result
}

/*
Section: Misc
*/

/// Deprecated. Use `String::from_utf16`.
#[deprecated = "Replaced by String::from_utf16"]
pub fn from_utf16(v: &[u16]) -> Option<String> {
    String::from_utf16(v)
}

/// Deprecated. Use `String::from_utf16_lossy`.
#[deprecated = "Replaced by String::from_utf16_lossy"]
pub fn from_utf16_lossy(v: &[u16]) -> String {
    String::from_utf16_lossy(v)
}

// 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 & 63u8) as u32)
)

/// Deprecated. Use `String::from_utf8_lossy`.
#[deprecated = "Replaced by String::from_utf8_lossy"]
pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> MaybeOwned<'a> {
    String::from_utf8_lossy(v)
}

/*
Section: MaybeOwned
*/

/// A string type that can hold either a `String` or a `&str`.
/// This can be useful as an optimization when an allocation is sometimes
/// needed but not always.
pub enum MaybeOwned<'a> {
    /// A borrowed string.
    Slice(&'a str),
    /// An owned string.
    Owned(String)
}

/// A specialization of `MaybeOwned` to be sendable.
pub type SendStr = MaybeOwned<'static>;

impl<'a> MaybeOwned<'a> {
    /// Returns `true` if this `MaybeOwned` wraps an owned string.
    ///
    /// # Example
    ///
    /// ```rust
    /// let string = String::from_str("orange");
    /// let maybe_owned_string = string.into_maybe_owned();
    /// assert_eq!(true, maybe_owned_string.is_owned());
    /// ```
    #[inline]
    pub fn is_owned(&self) -> bool {
        match *self {
            Slice(_) => false,
            Owned(_) => true
        }
    }

    /// Returns `true` if this `MaybeOwned` wraps a borrowed string.
    ///
    /// # Example
    ///
    /// ```rust
    /// let string = "orange";
    /// let maybe_owned_string = string.as_slice().into_maybe_owned();
    /// assert_eq!(true, maybe_owned_string.is_slice());
    /// ```
    #[inline]
    pub fn is_slice(&self) -> bool {
        match *self {
            Slice(_) => true,
            Owned(_) => false
        }
    }
}

/// Trait for moving into a `MaybeOwned`.
pub trait IntoMaybeOwned<'a> {
    /// Moves `self` into a `MaybeOwned`.
    fn into_maybe_owned(self) -> MaybeOwned<'a>;
}

impl<'a> IntoMaybeOwned<'a> for String {
    /// # Example
    ///
    /// ```rust
    /// let owned_string = String::from_str("orange");
    /// let maybe_owned_string = owned_string.into_maybe_owned();
    /// assert_eq!(true, maybe_owned_string.is_owned());
    /// ```
    #[inline]
    fn into_maybe_owned(self) -> MaybeOwned<'a> {
        Owned(self)
    }
}

impl<'a> IntoMaybeOwned<'a> for &'a str {
    /// # Example
    ///
    /// ```rust
    /// let string = "orange";
    /// let maybe_owned_str = string.as_slice().into_maybe_owned();
    /// assert_eq!(false, maybe_owned_str.is_owned());
    /// ```
    #[inline]
    fn into_maybe_owned(self) -> MaybeOwned<'a> { Slice(self) }
}

impl<'a> IntoMaybeOwned<'a> for MaybeOwned<'a> {
    /// # Example
    ///
    /// ```rust
    /// let str = "orange";
    /// let maybe_owned_str = str.as_slice().into_maybe_owned();
    /// let maybe_maybe_owned_str = maybe_owned_str.into_maybe_owned();
    /// assert_eq!(false, maybe_maybe_owned_str.is_owned());
    /// ```
    #[inline]
    fn into_maybe_owned(self) -> MaybeOwned<'a> { self }
}

impl<'a> PartialEq for MaybeOwned<'a> {
    #[inline]
    fn eq(&self, other: &MaybeOwned) -> bool {
        self.as_slice() == other.as_slice()
    }
}

impl<'a> Eq for MaybeOwned<'a> {}

impl<'a> PartialOrd for MaybeOwned<'a> {
    #[inline]
    fn partial_cmp(&self, other: &MaybeOwned) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl<'a> Ord for MaybeOwned<'a> {
    #[inline]
    fn cmp(&self, other: &MaybeOwned) -> Ordering {
        self.as_slice().cmp(&other.as_slice())
    }
}

impl<'a, S: Str> Equiv<S> for MaybeOwned<'a> {
    #[inline]
    fn equiv(&self, other: &S) -> bool {
        self.as_slice() == other.as_slice()
    }
}

impl<'a> Str for MaybeOwned<'a> {
    #[inline]
    fn as_slice<'b>(&'b self) -> &'b str {
        match *self {
            Slice(s) => s,
            Owned(ref s) => s.as_slice()
        }
    }
}

impl<'a> StrAllocating for MaybeOwned<'a> {
    #[inline]
    fn into_string(self) -> String {
        match self {
            Slice(s) => String::from_str(s),
            Owned(s) => s
        }
    }
}

impl<'a> Collection for MaybeOwned<'a> {
    #[inline]
    fn len(&self) -> uint { self.as_slice().len() }
}

impl<'a> Clone for MaybeOwned<'a> {
    #[inline]
    fn clone(&self) -> MaybeOwned<'a> {
        match *self {
            Slice(s) => Slice(s),
            Owned(ref s) => Owned(String::from_str(s.as_slice()))
        }
    }
}

impl<'a> Default for MaybeOwned<'a> {
    #[inline]
    fn default() -> MaybeOwned<'a> { Slice("") }
}

impl<'a, H: hash::Writer> hash::Hash<H> for MaybeOwned<'a> {
    #[inline]
    fn hash(&self, hasher: &mut H) {
        self.as_slice().hash(hasher)
    }
}

impl<'a> fmt::Show for MaybeOwned<'a> {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Slice(ref s) => s.fmt(f),
            Owned(ref s) => s.fmt(f)
        }
    }
}

/// Unsafe string operations.
pub mod raw {
    use string;
    use string::String;
    use vec::Vec;

    use MutableSeq;

    pub use core::str::raw::{from_utf8, c_str_to_static_slice, slice_bytes};
    pub use core::str::raw::{slice_unchecked};

    /// Deprecated. Replaced by `string::raw::from_buf_len`
    #[deprecated = "Use string::raw::from_buf_len"]
    pub unsafe fn from_buf_len(buf: *const u8, len: uint) -> String {
        string::raw::from_buf_len(buf, len)
    }

    /// Deprecated. Use `string::raw::from_buf`
    #[deprecated = "Use string::raw::from_buf"]
    pub unsafe fn from_c_str(c_string: *const i8) -> String {
        string::raw::from_buf(c_string as *const u8)
    }

    /// Deprecated. Replaced by `string::raw::from_utf8`
    #[deprecated = "Use string::raw::from_utf8"]
    pub unsafe fn from_utf8_owned(v: Vec<u8>) -> String {
        string::raw::from_utf8(v)
    }

    /// Deprecated. Use `string::raw::from_utf8`
    #[deprecated = "Use string::raw::from_utf8"]
    pub unsafe fn from_byte(u: u8) -> String {
        string::raw::from_utf8(vec![u])
    }
}

/*
Section: Trait implementations
*/

/// Any string that can be represented as a slice.
pub trait StrAllocating: Str {
    /// Converts `self` into a `String`, not making a copy if possible.
    fn into_string(self) -> String;

    #[allow(missing_doc)]
    #[deprecated = "replaced by .into_string()"]
    fn into_owned(self) -> String {
        self.into_string()
    }

    /// Escapes each char in `s` with `char::escape_default`.
    fn escape_default(&self) -> String {
        let me = self.as_slice();
        let mut out = String::with_capacity(me.len());
        for c in me.chars() {
            c.escape_default(|c| out.push_char(c));
        }
        out
    }

    /// Escapes each char in `s` with `char::escape_unicode`.
    fn escape_unicode(&self) -> String {
        let me = self.as_slice();
        let mut out = String::with_capacity(me.len());
        for c in me.chars() {
            c.escape_unicode(|c| out.push_char(c));
        }
        out
    }

    /// Replaces all occurrences of one string with another.
    ///
    /// # Arguments
    ///
    /// * `from` - The string to replace
    /// * `to` - The replacement string
    ///
    /// # Return value
    ///
    /// The original string with all occurrences of `from` replaced with `to`.
    ///
    /// # Example
    ///
    /// ```rust
    /// let s = "Do you know the muffin man,
    /// The muffin man, the muffin man, ...".to_string();
    ///
    /// assert_eq!(s.replace("muffin man", "little lamb"),
    ///            "Do you know the little lamb,
    /// The little lamb, the little lamb, ...".to_string());
    ///
    /// // not found, so no change.
    /// assert_eq!(s.replace("cookie monster", "little lamb"), s);
    /// ```
    fn replace(&self, from: &str, to: &str) -> String {
        let me = self.as_slice();
        let mut result = String::new();
        let mut last_end = 0;
        for (start, end) in me.match_indices(from) {
            result.push_str(unsafe{raw::slice_bytes(me, last_end, start)});
            result.push_str(to);
            last_end = end;
        }
        result.push_str(unsafe{raw::slice_bytes(me, last_end, me.len())});
        result
    }

    #[allow(missing_doc)]
    #[deprecated = "obsolete, use `to_string`"]
    #[inline]
    fn to_owned(&self) -> String {
        unsafe {
            mem::transmute(Vec::from_slice(self.as_slice().as_bytes()))
        }
    }

    /// Converts to a vector of `u16` encoded as UTF-16.
    #[deprecated = "use `utf16_units` instead"]
    fn to_utf16(&self) -> Vec<u16> {
        self.as_slice().utf16_units().collect::<Vec<u16>>()
    }

    /// Given a string, makes a new string with repeated copies of it.
    fn repeat(&self, nn: uint) -> String {
        let me = self.as_slice();
        let mut ret = String::with_capacity(nn * me.len());
        for _ in range(0, nn) {
            ret.push_str(me);
        }
        ret
    }

    /// Returns the Levenshtein Distance between two strings.
    fn lev_distance(&self, t: &str) -> uint {
        let me = self.as_slice();
        let slen = me.len();
        let tlen = t.len();

        if slen == 0 { return tlen; }
        if tlen == 0 { return slen; }

        let mut dcol = Vec::from_fn(tlen + 1, |x| x);

        for (i, sc) in me.chars().enumerate() {

            let mut current = i;
            *dcol.get_mut(0) = current + 1;

            for (j, tc) in t.chars().enumerate() {

                let next = dcol[j + 1];

                if sc == tc {
                    *dcol.get_mut(j + 1) = current;
                } else {
                    *dcol.get_mut(j + 1) = cmp::min(current, next);
                    *dcol.get_mut(j + 1) = cmp::min(dcol[j + 1],
                                                    dcol[j]) + 1;
                }

                current = next;
            }
        }

        return dcol[tlen];
    }

    /// Returns an iterator over the string in Unicode Normalization Form D
    /// (canonical decomposition).
    #[inline]
    fn nfd_chars<'a>(&'a self) -> Decompositions<'a> {
        Decompositions {
            iter: self.as_slice().chars(),
            buffer: Vec::new(),
            sorted: false,
            kind: Canonical
        }
    }

    /// Returns an iterator over the string in Unicode Normalization Form KD
    /// (compatibility decomposition).
    #[inline]
    fn nfkd_chars<'a>(&'a self) -> Decompositions<'a> {
        Decompositions {
            iter: self.as_slice().chars(),
            buffer: Vec::new(),
            sorted: false,
            kind: Compatible
        }
    }

    /// An Iterator over the string in Unicode Normalization Form C
    /// (canonical decomposition followed by canonical composition).
    #[inline]
    fn nfc_chars<'a>(&'a self) -> Recompositions<'a> {
        Recompositions {
            iter: self.nfd_chars(),
            state: Composing,
            buffer: RingBuf::new(),
            composee: None,
            last_ccc: None
        }
    }

    /// An Iterator over the string in Unicode Normalization Form KC
    /// (compatibility decomposition followed by canonical composition).
    #[inline]
    fn nfkc_chars<'a>(&'a self) -> Recompositions<'a> {
        Recompositions {
            iter: self.nfkd_chars(),
            state: Composing,
            buffer: RingBuf::new(),
            composee: None,
            last_ccc: None
        }
    }
}

impl<'a> StrAllocating for &'a str {
    #[inline]
    fn into_string(self) -> String {
        String::from_str(self)
    }
}

#[cfg(test)]
mod tests {
    use std::iter::AdditiveIterator;
    use std::iter::range;
    use std::default::Default;
    use std::char::Char;
    use std::clone::Clone;
    use std::cmp::{Equal, Greater, Less, Ord, PartialOrd, Equiv};
    use std::option::{Some, None};
    use std::ptr::RawPtr;
    use std::iter::{Iterator, DoubleEndedIterator};
    use {Collection, MutableSeq};

    use super::*;
    use std::slice::{Slice, ImmutableSlice};
    use string::String;
    use vec::Vec;

    use unicode::char::UnicodeChar;

    #[test]
    fn test_eq_slice() {
        assert!((eq_slice("foobar".slice(0, 3), "foo")));
        assert!((eq_slice("barfoo".slice(3, 6), "foo")));
        assert!((!eq_slice("foo1", "foo2")));
    }

    #[test]
    fn test_le() {
        assert!("" <= "");
        assert!("" <= "foo");
        assert!("foo" <= "foo");
        assert!("foo" != "bar");
    }

    #[test]
    fn test_len() {
        assert_eq!("".len(), 0u);
        assert_eq!("hello world".len(), 11u);
        assert_eq!("\x63".len(), 1u);
        assert_eq!("\xa2".len(), 2u);
        assert_eq!("\u03c0".len(), 2u);
        assert_eq!("\u2620".len(), 3u);
        assert_eq!("\U0001d11e".len(), 4u);

        assert_eq!("".char_len(), 0u);
        assert_eq!("hello world".char_len(), 11u);
        assert_eq!("\x63".char_len(), 1u);
        assert_eq!("\xa2".char_len(), 1u);
        assert_eq!("\u03c0".char_len(), 1u);
        assert_eq!("\u2620".char_len(), 1u);
        assert_eq!("\U0001d11e".char_len(), 1u);
        assert_eq!("ประเทศไทย中华Việt Nam".char_len(), 19u);

        assert_eq!("ｈｅｌｌｏ".width(false), 10u);
        assert_eq!("ｈｅｌｌｏ".width(true), 10u);
        assert_eq!("\0\0\0\0\0".width(false), 0u);
        assert_eq!("\0\0\0\0\0".width(true), 0u);
        assert_eq!("".width(false), 0u);
        assert_eq!("".width(true), 0u);
        assert_eq!("\u2081\u2082\u2083\u2084".width(false), 4u);
        assert_eq!("\u2081\u2082\u2083\u2084".width(true), 8u);
    }

    #[test]
    fn test_find() {
        assert_eq!("hello".find('l'), Some(2u));
        assert_eq!("hello".find(|c:char| c == 'o'), Some(4u));
        assert!("hello".find('x').is_none());
        assert!("hello".find(|c:char| c == 'x').is_none());
        assert_eq!("ประเทศไทย中华Việt Nam".find('华'), Some(30u));
        assert_eq!("ประเทศไทย中华Việt Nam".find(|c: char| c == '华'), Some(30u));
    }

    #[test]
    fn test_rfind() {
        assert_eq!("hello".rfind('l'), Some(3u));
        assert_eq!("hello".rfind(|c:char| c == 'o'), Some(4u));
        assert!("hello".rfind('x').is_none());
        assert!("hello".rfind(|c:char| c == 'x').is_none());
        assert_eq!("ประเทศไทย中华Việt Nam".rfind('华'), Some(30u));
        assert_eq!("ประเทศไทย中华Việt Nam".rfind(|c: char| c == '华'), Some(30u));
    }

    #[test]
    fn test_collect() {
        let empty = String::from_str("");
        let s: String = empty.as_slice().chars().collect();
        assert_eq!(empty, s);
        let data = String::from_str("ประเทศไทย中");
        let s: String = data.as_slice().chars().collect();
        assert_eq!(data, s);
    }

    #[test]
    fn test_into_bytes() {
        let data = String::from_str("asdf");
        let buf = data.into_bytes();
        assert_eq!(b"asdf", buf.as_slice());
    }

    #[test]
    fn test_find_str() {
        // byte positions
        assert_eq!("".find_str(""), Some(0u));
        assert!("banana".find_str("apple pie").is_none());

        let data = "abcabc";
        assert_eq!(data.slice(0u, 6u).find_str("ab"), Some(0u));
        assert_eq!(data.slice(2u, 6u).find_str("ab"), Some(3u - 2u));
        assert!(data.slice(2u, 4u).find_str("ab").is_none());

        let string = "ประเทศไทย中华Việt Nam";
        let mut data = String::from_str(string);
        data.push_str(string);
        assert!(data.as_slice().find_str("ไท华").is_none());
        assert_eq!(data.as_slice().slice(0u, 43u).find_str(""), Some(0u));
        assert_eq!(data.as_slice().slice(6u, 43u).find_str(""), Some(6u - 6u));

        assert_eq!(data.as_slice().slice(0u, 43u).find_str("ประ"), Some( 0u));
        assert_eq!(data.as_slice().slice(0u, 43u).find_str("ทศไ"), Some(12u));
        assert_eq!(data.as_slice().slice(0u, 43u).find_str("ย中"), Some(24u));
        assert_eq!(data.as_slice().slice(0u, 43u).find_str("iệt"), Some(34u));
        assert_eq!(data.as_slice().slice(0u, 43u).find_str("Nam"), Some(40u));

        assert_eq!(data.as_slice().slice(43u, 86u).find_str("ประ"), Some(43u - 43u));
        assert_eq!(data.as_slice().slice(43u, 86u).find_str("ทศไ"), Some(55u - 43u));
        assert_eq!(data.as_slice().slice(43u, 86u).find_str("ย中"), Some(67u - 43u));
        assert_eq!(data.as_slice().slice(43u, 86u).find_str("iệt"), Some(77u - 43u));
        assert_eq!(data.as_slice().slice(43u, 86u).find_str("Nam"), Some(83u - 43u));
    }

    #[test]
    fn test_slice_chars() {
        fn t(a: &str, b: &str, start: uint) {
            assert_eq!(a.slice_chars(start, start + b.char_len()), b);
        }
        t("", "", 0);
        t("hello", "llo", 2);
        t("hello", "el", 1);
        t("αβλ", "β", 1);
        t("αβλ", "", 3);
        assert_eq!("ะเทศไท", "ประเทศไทย中华Việt Nam".slice_chars(2, 8));
    }

    #[test]
    fn test_concat() {
        fn t(v: &[String], s: &str) {
            assert_eq!(v.concat().as_slice(), s);
        }
        t([String::from_str("you"), String::from_str("know"),
           String::from_str("I'm"),
           String::from_str("no"), String::from_str("good")],
          "youknowI'mnogood");
        let v: &[String] = [];
        t(v, "");
        t([String::from_str("hi")], "hi");
    }

    #[test]
    fn test_connect() {
        fn t(v: &[String], sep: &str, s: &str) {
            assert_eq!(v.connect(sep).as_slice(), s);
        }
        t([String::from_str("you"), String::from_str("know"),
           String::from_str("I'm"),
           String::from_str("no"), String::from_str("good")],
          " ", "you know I'm no good");
        let v: &[String] = [];
        t(v, " ", "");
        t([String::from_str("hi")], " ", "hi");
    }

    #[test]
    fn test_concat_slices() {
        fn t(v: &[&str], s: &str) {
            assert_eq!(v.concat().as_slice(), s);
        }
        t(["you", "know", "I'm", "no", "good"], "youknowI'mnogood");
        let v: &[&str] = [];
        t(v, "");
        t(["hi"], "hi");
    }

    #[test]
    fn test_connect_slices() {
        fn t(v: &[&str], sep: &str, s: &str) {
            assert_eq!(v.connect(sep).as_slice(), s);
        }
        t(["you", "know", "I'm", "no", "good"],
          " ", "you know I'm no good");
        t([], " ", "");
        t(["hi"], " ", "hi");
    }

    #[test]
    fn test_repeat() {
        assert_eq!("x".repeat(4), String::from_str("xxxx"));
        assert_eq!("hi".repeat(4), String::from_str("hihihihi"));
        assert_eq!("ไท华".repeat(3), String::from_str("ไท华ไท华ไท华"));
        assert_eq!("".repeat(4), String::from_str(""));
        assert_eq!("hi".repeat(0), String::from_str(""));
    }

    #[test]
    fn test_unsafe_slice() {
        assert_eq!("ab", unsafe {raw::slice_bytes("abc", 0, 2)});
        assert_eq!("bc", unsafe {raw::slice_bytes("abc", 1, 3)});
        assert_eq!("", unsafe {raw::slice_bytes("abc", 1, 1)});
        fn a_million_letter_a() -> String {
            let mut i = 0u;
            let mut rs = String::new();
            while i < 100000 {
                rs.push_str("aaaaaaaaaa");
                i += 1;
            }
            rs
        }
        fn half_a_million_letter_a() -> String {
            let mut i = 0u;
            let mut rs = String::new();
            while i < 100000 {
                rs.push_str("aaaaa");
                i += 1;
            }
            rs
        }
        let letters = a_million_letter_a();
        assert!(half_a_million_letter_a() ==
            unsafe {String::from_str(raw::slice_bytes(letters.as_slice(),
                                     0u,
                                     500000))});
    }

    #[test]
    fn test_starts_with() {
        assert!(("".starts_with("")));
        assert!(("abc".starts_with("")));
        assert!(("abc".starts_with("a")));
        assert!((!"a".starts_with("abc")));
        assert!((!"".starts_with("abc")));
        assert!((!"ödd".starts_with("-")));
        assert!(("ödd".starts_with("öd")));
    }

    #[test]
    fn test_ends_with() {
        assert!(("".ends_with("")));
        assert!(("abc".ends_with("")));
        assert!(("abc".ends_with("c")));
        assert!((!"a".ends_with("abc")));
        assert!((!"".ends_with("abc")));
        assert!((!"ddö".ends_with("-")));
        assert!(("ddö".ends_with("dö")));
    }

    #[test]
    fn test_is_empty() {
        assert!("".is_empty());
        assert!(!"a".is_empty());
    }

    #[test]
    fn test_replace() {
        let a = "a";
        assert_eq!("".replace(a, "b"), String::from_str(""));
        assert_eq!("a".replace(a, "b"), String::from_str("b"));
        assert_eq!("ab".replace(a, "b"), String::from_str("bb"));
        let test = "test";
        assert!(" test test ".replace(test, "toast") ==
            String::from_str(" toast toast "));
        assert_eq!(" test test ".replace(test, ""), String::from_str("   "));
    }

    #[test]
    fn test_replace_2a() {
        let data = "ประเทศไทย中华";
        let repl = "دولة الكويت";

        let a = "ประเ";
        let a2 = "دولة الكويتทศไทย中华";
        assert_eq!(data.replace(a, repl).as_slice(), a2);
    }

    #[test]
    fn test_replace_2b() {
        let data = "ประเทศไทย中华";
        let repl = "دولة الكويت";

        let b = "ะเ";
        let b2 = "ปรدولة الكويتทศไทย中华";
        assert_eq!(data.replace(b, repl).as_slice(), b2);
    }

    #[test]
    fn test_replace_2c() {
        let data = "ประเทศไทย中华";
        let repl = "دولة الكويت";

        let c = "中华";
        let c2 = "ประเทศไทยدولة الكويت";
        assert_eq!(data.replace(c, repl).as_slice(), c2);
    }

    #[test]
    fn test_replace_2d() {
        let data = "ประเทศไทย中华";
        let repl = "دولة الكويت";

        let d = "ไท华";
        assert_eq!(data.replace(d, repl).as_slice(), data);
    }

    #[test]
    fn test_slice() {
        assert_eq!("ab", "abc".slice(0, 2));
        assert_eq!("bc", "abc".slice(1, 3));
        assert_eq!("", "abc".slice(1, 1));
        assert_eq!("\u65e5", "\u65e5\u672c".slice(0, 3));

        let data = "ประเทศไทย中华";
        assert_eq!("ป", data.slice(0, 3));
        assert_eq!("ร", data.slice(3, 6));
        assert_eq!("", data.slice(3, 3));
        assert_eq!("华", data.slice(30, 33));

        fn a_million_letter_x() -> String {
            let mut i = 0u;
            let mut rs = String::new();
            while i < 100000 {
                rs.push_str("华华华华华华华华华华");
                i += 1;
            }
            rs
        }
        fn half_a_million_letter_x() -> String {
            let mut i = 0u;
            let mut rs = String::new();
            while i < 100000 {
                rs.push_str("华华华华华");
                i += 1;
            }
            rs
        }
        let letters = a_million_letter_x();
        assert!(half_a_million_letter_x() ==
            String::from_str(letters.as_slice().slice(0u, 3u * 500000u)));
    }

    #[test]
    fn test_slice_2() {
        let ss = "中华Việt Nam";

        assert_eq!("华", ss.slice(3u, 6u));
        assert_eq!("Việt Nam", ss.slice(6u, 16u));

        assert_eq!("ab", "abc".slice(0u, 2u));
        assert_eq!("bc", "abc".slice(1u, 3u));
        assert_eq!("", "abc".slice(1u, 1u));

        assert_eq!("中", ss.slice(0u, 3u));
        assert_eq!("华V", ss.slice(3u, 7u));
        assert_eq!("", ss.slice(3u, 3u));
        /*0: 中
          3: 华
          6: V
          7: i
          8: ệ
         11: t
         12:
         13: N
         14: a
         15: m */
    }

    #[test]
    #[should_fail]
    fn test_slice_fail() {
        "中华Việt Nam".slice(0u, 2u);
    }

    #[test]
    fn test_slice_from() {
        assert_eq!("abcd".slice_from(0), "abcd");
        assert_eq!("abcd".slice_from(2), "cd");
        assert_eq!("abcd".slice_from(4), "");
    }
    #[test]
    fn test_slice_to() {
        assert_eq!("abcd".slice_to(0), "");
        assert_eq!("abcd".slice_to(2), "ab");
        assert_eq!("abcd".slice_to(4), "abcd");
    }

    #[test]
    fn test_trim_left_chars() {
        let v: &[char] = &[];
        assert_eq!(" *** foo *** ".trim_left_chars(v), " *** foo *** ");
        let chars: &[char] = &['*', ' '];
        assert_eq!(" *** foo *** ".trim_left_chars(chars), "foo *** ");
        assert_eq!(" ***  *** ".trim_left_chars(chars), "");
        assert_eq!("foo *** ".trim_left_chars(chars), "foo *** ");

        assert_eq!("11foo1bar11".trim_left_chars('1'), "foo1bar11");
        let chars: &[char] = &['1', '2'];
        assert_eq!("12foo1bar12".trim_left_chars(chars), "foo1bar12");
        assert_eq!("123foo1bar123".trim_left_chars(|c: char| c.is_digit()), "foo1bar123");
    }

    #[test]
    fn test_trim_right_chars() {
        let v: &[char] = &[];
        assert_eq!(" *** foo *** ".trim_right_chars(v), " *** foo *** ");
        let chars: &[char] = &['*', ' '];
        assert_eq!(" *** foo *** ".trim_right_chars(chars), " *** foo");
        assert_eq!(" ***  *** ".trim_right_chars(chars), "");
        assert_eq!(" *** foo".trim_right_chars(chars), " *** foo");

        assert_eq!("11foo1bar11".trim_right_chars('1'), "11foo1bar");
        let chars: &[char] = &['1', '2'];
        assert_eq!("12foo1bar12".trim_right_chars(chars), "12foo1bar");
        assert_eq!("123foo1bar123".trim_right_chars(|c: char| c.is_digit()), "123foo1bar");
    }

    #[test]
    fn test_trim_chars() {
        let v: &[char] = &[];
        assert_eq!(" *** foo *** ".trim_chars(v), " *** foo *** ");
        let chars: &[char] = &['*', ' '];
        assert_eq!(" *** foo *** ".trim_chars(chars), "foo");
        assert_eq!(" ***  *** ".trim_chars(chars), "");
        assert_eq!("foo".trim_chars(chars), "foo");

        assert_eq!("11foo1bar11".trim_chars('1'), "foo1bar");
        let chars: &[char] = &['1', '2'];
        assert_eq!("12foo1bar12".trim_chars(chars), "foo1bar");
        assert_eq!("123foo1bar123".trim_chars(|c: char| c.is_digit()), "foo1bar");
    }

    #[test]
    fn test_trim_left() {
        assert_eq!("".trim_left(), "");
        assert_eq!("a".trim_left(), "a");
        assert_eq!("    ".trim_left(), "");
        assert_eq!("     blah".trim_left(), "blah");
        assert_eq!("   \u3000  wut".trim_left(), "wut");
        assert_eq!("hey ".trim_left(), "hey ");
    }

    #[test]
    fn test_trim_right() {
        assert_eq!("".trim_right(), "");
        assert_eq!("a".trim_right(), "a");
        assert_eq!("    ".trim_right(), "");
        assert_eq!("blah     ".trim_right(), "blah");
        assert_eq!("wut   \u3000  ".trim_right(), "wut");
        assert_eq!(" hey".trim_right(), " hey");
    }

    #[test]
    fn test_trim() {
        assert_eq!("".trim(), "");
        assert_eq!("a".trim(), "a");
        assert_eq!("    ".trim(), "");
        assert_eq!("    blah     ".trim(), "blah");
        assert_eq!("\nwut   \u3000  ".trim(), "wut");
        assert_eq!(" hey dude ".trim(), "hey dude");
    }

    #[test]
    fn test_is_whitespace() {
        assert!("".is_whitespace());
        assert!(" ".is_whitespace());
        assert!("\u2009".is_whitespace()); // Thin space
        assert!("  \n\t   ".is_whitespace());
        assert!(!"   _   ".is_whitespace());
    }

    #[test]
    fn test_slice_shift_char() {
        let data = "ประเทศไทย中";
        assert_eq!(data.slice_shift_char(), (Some('ป'), "ระเทศไทย中"));
    }

    #[test]
    fn test_slice_shift_char_2() {
        let empty = "";
        assert_eq!(empty.slice_shift_char(), (None, ""));
    }

    #[test]
    fn test_is_utf8() {
        // deny overlong encodings
        assert!(!is_utf8([0xc0, 0x80]));
        assert!(!is_utf8([0xc0, 0xae]));
        assert!(!is_utf8([0xe0, 0x80, 0x80]));
        assert!(!is_utf8([0xe0, 0x80, 0xaf]));
        assert!(!is_utf8([0xe0, 0x81, 0x81]));
        assert!(!is_utf8([0xf0, 0x82, 0x82, 0xac]));
        assert!(!is_utf8([0xf4, 0x90, 0x80, 0x80]));

        // deny surrogates
        assert!(!is_utf8([0xED, 0xA0, 0x80]));
        assert!(!is_utf8([0xED, 0xBF, 0xBF]));

        assert!(is_utf8([0xC2, 0x80]));
        assert!(is_utf8([0xDF, 0xBF]));
        assert!(is_utf8([0xE0, 0xA0, 0x80]));
        assert!(is_utf8([0xED, 0x9F, 0xBF]));
        assert!(is_utf8([0xEE, 0x80, 0x80]));
        assert!(is_utf8([0xEF, 0xBF, 0xBF]));
        assert!(is_utf8([0xF0, 0x90, 0x80, 0x80]));
        assert!(is_utf8([0xF4, 0x8F, 0xBF, 0xBF]));
    }

    #[test]
    fn test_is_utf16() {
        macro_rules! pos ( ($($e:expr),*) => { { $(assert!(is_utf16($e));)* } });

        // non-surrogates
        pos!([0x0000],
             [0x0001, 0x0002],
             [0xD7FF],
             [0xE000]);

        // surrogate pairs (randomly generated with Python 3's
        // .encode('utf-16be'))
        pos!([0xdb54, 0xdf16, 0xd880, 0xdee0, 0xdb6a, 0xdd45],
             [0xd91f, 0xdeb1, 0xdb31, 0xdd84, 0xd8e2, 0xde14],
             [0xdb9f, 0xdc26, 0xdb6f, 0xde58, 0xd850, 0xdfae]);

        // mixtures (also random)
        pos!([0xd921, 0xdcc2, 0x002d, 0x004d, 0xdb32, 0xdf65],
             [0xdb45, 0xdd2d, 0x006a, 0xdacd, 0xddfe, 0x0006],
             [0x0067, 0xd8ff, 0xddb7, 0x000f, 0xd900, 0xdc80]);

        // negative tests
        macro_rules! neg ( ($($e:expr),*) => { { $(assert!(!is_utf16($e));)* } });

        neg!(
            // surrogate + regular unit
            [0xdb45, 0x0000],
            // surrogate + lead surrogate
            [0xd900, 0xd900],
            // unterminated surrogate
            [0xd8ff],
            // trail surrogate without a lead
            [0xddb7]);

        // random byte sequences that Python 3's .decode('utf-16be')
        // failed on
        neg!([0x5b3d, 0x0141, 0xde9e, 0x8fdc, 0xc6e7],
             [0xdf5a, 0x82a5, 0x62b9, 0xb447, 0x92f3],
             [0xda4e, 0x42bc, 0x4462, 0xee98, 0xc2ca],
             [0xbe00, 0xb04a, 0x6ecb, 0xdd89, 0xe278],
             [0x0465, 0xab56, 0xdbb6, 0xa893, 0x665e],
             [0x6b7f, 0x0a19, 0x40f4, 0xa657, 0xdcc5],
             [0x9b50, 0xda5e, 0x24ec, 0x03ad, 0x6dee],
             [0x8d17, 0xcaa7, 0xf4ae, 0xdf6e, 0xbed7],
             [0xdaee, 0x2584, 0x7d30, 0xa626, 0x121a],
             [0xd956, 0x4b43, 0x7570, 0xccd6, 0x4f4a],
             [0x9dcf, 0x1b49, 0x4ba5, 0xfce9, 0xdffe],
             [0x6572, 0xce53, 0xb05a, 0xf6af, 0xdacf],
             [0x1b90, 0x728c, 0x9906, 0xdb68, 0xf46e],
             [0x1606, 0xbeca, 0xbe76, 0x860f, 0xdfa5],
             [0x8b4f, 0xde7a, 0xd220, 0x9fac, 0x2b6f],
             [0xb8fe, 0xebbe, 0xda32, 0x1a5f, 0x8b8b],
             [0x934b, 0x8956, 0xc434, 0x1881, 0xddf7],
             [0x5a95, 0x13fc, 0xf116, 0xd89b, 0x93f9],
             [0xd640, 0x71f1, 0xdd7d, 0x77eb, 0x1cd8],
             [0x348b, 0xaef0, 0xdb2c, 0xebf1, 0x1282],
             [0x50d7, 0xd824, 0x5010, 0xb369, 0x22ea]);
    }

    #[test]
    fn test_as_bytes() {
        // no null
        let v = [
            224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
            184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
            109
        ];
        let b: &[u8] = &[];
        assert_eq!("".as_bytes(), b);
        assert_eq!("abc".as_bytes(), b"abc");
        assert_eq!("ศไทย中华Việt Nam".as_bytes(), v.as_slice());
    }

    #[test]
    #[should_fail]
    fn test_as_bytes_fail() {
        // Don't double free. (I'm not sure if this exercises the
        // original problem code path anymore.)
        let s = String::from_str("");
        let _bytes = s.as_bytes();
        fail!();
    }

    #[test]
    fn test_as_ptr() {
        let buf = "hello".as_ptr();
        unsafe {
            assert_eq!(*buf.offset(0), b'h');
            assert_eq!(*buf.offset(1), b'e');
            assert_eq!(*buf.offset(2), b'l');
            assert_eq!(*buf.offset(3), b'l');
            assert_eq!(*buf.offset(4), b'o');
        }
    }

    #[test]
    fn test_subslice_offset() {
        let a = "kernelsprite";
        let b = a.slice(7, a.len());
        let c = a.slice(0, a.len() - 6);
        assert_eq!(a.subslice_offset(b), 7);
        assert_eq!(a.subslice_offset(c), 0);

        let string = "a\nb\nc";
        let lines: Vec<&str> = string.lines().collect();
        let lines = lines.as_slice();
        assert_eq!(string.subslice_offset(lines[0]), 0);
        assert_eq!(string.subslice_offset(lines[1]), 2);
        assert_eq!(string.subslice_offset(lines[2]), 4);
    }

    #[test]
    #[should_fail]
    fn test_subslice_offset_2() {
        let a = "alchemiter";
        let b = "cruxtruder";
        a.subslice_offset(b);
    }

    #[test]
    fn vec_str_conversions() {
        let s1: String = String::from_str("All mimsy were the borogoves");

        let v: Vec<u8> = Vec::from_slice(s1.as_bytes());
        let s2: String = String::from_str(from_utf8(v.as_slice()).unwrap());
        let mut i: uint = 0u;
        let n1: uint = s1.len();
        let n2: uint = v.len();
        assert_eq!(n1, n2);
        while i < n1 {
            let a: u8 = s1.as_bytes()[i];
            let b: u8 = s2.as_bytes()[i];
            debug!("{}", a);
            debug!("{}", b);
            assert_eq!(a, b);
            i += 1u;
        }
    }

    #[test]
    fn test_contains() {
        assert!("abcde".contains("bcd"));
        assert!("abcde".contains("abcd"));
        assert!("abcde".contains("bcde"));
        assert!("abcde".contains(""));
        assert!("".contains(""));
        assert!(!"abcde".contains("def"));
        assert!(!"".contains("a"));

        let data = "ประเทศไทย中华Việt Nam";
        assert!(data.contains("ประเ"));
        assert!(data.contains("ะเ"));
        assert!(data.contains("中华"));
        assert!(!data.contains("ไท华"));
    }

    #[test]
    fn test_contains_char() {
        assert!("abc".contains_char('b'));
        assert!("a".contains_char('a'));
        assert!(!"abc".contains_char('d'));
        assert!(!"".contains_char('a'));
    }

    #[test]
    fn test_truncate_utf16_at_nul() {
        let v = [];
        let b: &[u16] = &[];
        assert_eq!(truncate_utf16_at_nul(v), b);

        let v = [0, 2, 3];
        assert_eq!(truncate_utf16_at_nul(v), b);

        let v = [1, 0, 3];
        let b: &[u16] = &[1];
        assert_eq!(truncate_utf16_at_nul(v), b);

        let v = [1, 2, 0];
        let b: &[u16] = &[1, 2];
        assert_eq!(truncate_utf16_at_nul(v), b);

        let v = [1, 2, 3];
        let b: &[u16] = &[1, 2, 3];
        assert_eq!(truncate_utf16_at_nul(v), b);
    }

    #[test]
    fn test_char_at() {
        let s = "ศไทย中华Việt Nam";
        let v = vec!['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];
        let mut pos = 0;
        for ch in v.iter() {
            assert!(s.char_at(pos) == *ch);
            pos += String::from_char(1, *ch).len();
        }
    }

    #[test]
    fn test_char_at_reverse() {
        let s = "ศไทย中华Việt Nam";
        let v = vec!['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];
        let mut pos = s.len();
        for ch in v.iter().rev() {
            assert!(s.char_at_reverse(pos) == *ch);
            pos -= String::from_char(1, *ch).len();
        }
    }

    #[test]
    fn test_escape_unicode() {
        assert_eq!("abc".escape_unicode(), String::from_str("\\x61\\x62\\x63"));
        assert_eq!("a c".escape_unicode(), String::from_str("\\x61\\x20\\x63"));
        assert_eq!("\r\n\t".escape_unicode(), String::from_str("\\x0d\\x0a\\x09"));
        assert_eq!("'\"\\".escape_unicode(), String::from_str("\\x27\\x22\\x5c"));
        assert_eq!("\x00\x01\xfe\xff".escape_unicode(), String::from_str("\\x00\\x01\\xfe\\xff"));
        assert_eq!("\u0100\uffff".escape_unicode(), String::from_str("\\u0100\\uffff"));
        assert_eq!("\U00010000\U0010ffff".escape_unicode(),
                   String::from_str("\\U00010000\\U0010ffff"));
        assert_eq!("ab\ufb00".escape_unicode(), String::from_str("\\x61\\x62\\ufb00"));
        assert_eq!("\U0001d4ea\r".escape_unicode(), String::from_str("\\U0001d4ea\\x0d"));
    }

    #[test]
    fn test_escape_default() {
        assert_eq!("abc".escape_default(), String::from_str("abc"));
        assert_eq!("a c".escape_default(), String::from_str("a c"));
        assert_eq!("\r\n\t".escape_default(), String::from_str("\\r\\n\\t"));
        assert_eq!("'\"\\".escape_default(), String::from_str("\\'\\\"\\\\"));
        assert_eq!("\u0100\uffff".escape_default(), String::from_str("\\u0100\\uffff"));
        assert_eq!("\U00010000\U0010ffff".escape_default(),
                   String::from_str("\\U00010000\\U0010ffff"));
        assert_eq!("ab\ufb00".escape_default(), String::from_str("ab\\ufb00"));
        assert_eq!("\U0001d4ea\r".escape_default(), String::from_str("\\U0001d4ea\\r"));
    }

    #[test]
    fn test_total_ord() {
        "1234".cmp(&("123")) == Greater;
        "123".cmp(&("1234")) == Less;
        "1234".cmp(&("1234")) == Equal;
        "12345555".cmp(&("123456")) == Less;
        "22".cmp(&("1234")) == Greater;
    }

    #[test]
    fn test_char_range_at() {
        let data = "b¢€𤭢𤭢€¢b";
        assert_eq!('b', data.char_range_at(0).ch);
        assert_eq!('¢', data.char_range_at(1).ch);
        assert_eq!('€', data.char_range_at(3).ch);
        assert_eq!('𤭢', data.char_range_at(6).ch);
        assert_eq!('𤭢', data.char_range_at(10).ch);
        assert_eq!('€', data.char_range_at(14).ch);
        assert_eq!('¢', data.char_range_at(17).ch);
        assert_eq!('b', data.char_range_at(19).ch);
    }

    #[test]
    fn test_char_range_at_reverse_underflow() {
        assert_eq!("abc".char_range_at_reverse(0).next, 0);
    }

    #[test]
    fn test_iterator() {
        let s = "ศไทย中华Việt Nam";
        let v = ['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];

        let mut pos = 0;
        let mut it = s.chars();

        for c in it {
            assert_eq!(c, v[pos]);
            pos += 1;
        }
        assert_eq!(pos, v.len());
    }

    #[test]
    fn test_rev_iterator() {
        let s = "ศไทย中华Việt Nam";
        let v = ['m', 'a', 'N', ' ', 't', 'ệ','i','V','华','中','ย','ท','ไ','ศ'];

        let mut pos = 0;
        let mut it = s.chars().rev();

        for c in it {
            assert_eq!(c, v[pos]);
            pos += 1;
        }
        assert_eq!(pos, v.len());
    }

    #[test]
    fn test_chars_decoding() {
        let mut bytes = [0u8, ..4];
        for c in range(0u32, 0x110000).filter_map(|c| ::core::char::from_u32(c)) {
            let len = c.encode_utf8(bytes).unwrap_or(0);
            let s = ::core::str::from_utf8(bytes.slice_to(len)).unwrap();
            if Some(c) != s.chars().next() {
                fail!("character {:x}={} does not decode correctly", c as u32, c);
            }
        }
    }

    #[test]
    fn test_chars_rev_decoding() {
        let mut bytes = [0u8, ..4];
        for c in range(0u32, 0x110000).filter_map(|c| ::core::char::from_u32(c)) {
            let len = c.encode_utf8(bytes).unwrap_or(0);
            let s = ::core::str::from_utf8(bytes.slice_to(len)).unwrap();
            if Some(c) != s.chars().rev().next() {
                fail!("character {:x}={} does not decode correctly", c as u32, c);
            }
        }
    }

    #[test]
    fn test_iterator_clone() {
        let s = "ศไทย中华Việt Nam";
        let mut it = s.chars();
        it.next();
        assert!(it.zip(it.clone()).all(|(x,y)| x == y));
    }

    #[test]
    fn test_bytesator() {
        let s = "ศไทย中华Việt Nam";
        let v = [
            224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
            184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
            109
        ];
        let mut pos = 0;

        for b in s.bytes() {
            assert_eq!(b, v[pos]);
            pos += 1;
        }
    }

    #[test]
    fn test_bytes_revator() {
        let s = "ศไทย中华Việt Nam";
        let v = [
            224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
            184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
            109
        ];
        let mut pos = v.len();

        for b in s.bytes().rev() {
            pos -= 1;
            assert_eq!(b, v[pos]);
        }
    }

    #[test]
    fn test_char_indicesator() {
        let s = "ศไทย中华Việt Nam";
        let p = [0, 3, 6, 9, 12, 15, 18, 19, 20, 23, 24, 25, 26, 27];
        let v = ['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];

        let mut pos = 0;
        let mut it = s.char_indices();

        for c in it {
            assert_eq!(c, (p[pos], v[pos]));
            pos += 1;
        }
        assert_eq!(pos, v.len());
        assert_eq!(pos, p.len());
    }

    #[test]
    fn test_char_indices_revator() {
        let s = "ศไทย中华Việt Nam";
        let p = [27, 26, 25, 24, 23, 20, 19, 18, 15, 12, 9, 6, 3, 0];
        let v = ['m', 'a', 'N', ' ', 't', 'ệ','i','V','华','中','ย','ท','ไ','ศ'];

        let mut pos = 0;
        let mut it = s.char_indices().rev();

        for c in it {
            assert_eq!(c, (p[pos], v[pos]));
            pos += 1;
        }
        assert_eq!(pos, v.len());
        assert_eq!(pos, p.len());
    }

    #[test]
    fn test_split_char_iterator() {
        let data = "\nMäry häd ä little lämb\nLittle lämb\n";

        let split: Vec<&str> = data.split(' ').collect();
        assert_eq!( split, vec!["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

        let mut rsplit: Vec<&str> = data.split(' ').rev().collect();
        rsplit.reverse();
        assert_eq!(rsplit, vec!["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

        let split: Vec<&str> = data.split(|c: char| c == ' ').collect();
        assert_eq!( split, vec!["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

        let mut rsplit: Vec<&str> = data.split(|c: char| c == ' ').rev().collect();
        rsplit.reverse();
        assert_eq!(rsplit, vec!["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

        // Unicode
        let split: Vec<&str> = data.split('ä').collect();
        assert_eq!( split, vec!["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);

        let mut rsplit: Vec<&str> = data.split('ä').rev().collect();
        rsplit.reverse();
        assert_eq!(rsplit, vec!["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);

        let split: Vec<&str> = data.split(|c: char| c == 'ä').collect();
        assert_eq!( split, vec!["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);

        let mut rsplit: Vec<&str> = data.split(|c: char| c == 'ä').rev().collect();
        rsplit.reverse();
        assert_eq!(rsplit, vec!["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);
    }

    #[test]
    fn test_splitn_char_iterator() {
        let data = "\nMäry häd ä little lämb\nLittle lämb\n";

        let split: Vec<&str> = data.splitn(3, ' ').collect();
        assert_eq!(split, vec!["\nMäry", "häd", "ä", "little lämb\nLittle lämb\n"]);

        let split: Vec<&str> = data.splitn(3, |c: char| c == ' ').collect();
        assert_eq!(split, vec!["\nMäry", "häd", "ä", "little lämb\nLittle lämb\n"]);

        // Unicode
        let split: Vec<&str> = data.splitn(3, 'ä').collect();
        assert_eq!(split, vec!["\nM", "ry h", "d ", " little lämb\nLittle lämb\n"]);

        let split: Vec<&str> = data.splitn(3, |c: char| c == 'ä').collect();
        assert_eq!(split, vec!["\nM", "ry h", "d ", " little lämb\nLittle lämb\n"]);
    }

    #[test]
    fn test_rsplitn_char_iterator() {
        let data = "\nMäry häd ä little lämb\nLittle lämb\n";

        let mut split: Vec<&str> = data.rsplitn(3, ' ').collect();
        split.reverse();
        assert_eq!(split, vec!["\nMäry häd ä", "little", "lämb\nLittle", "lämb\n"]);

        let mut split: Vec<&str> = data.rsplitn(3, |c: char| c == ' ').collect();
        split.reverse();
        assert_eq!(split, vec!["\nMäry häd ä", "little", "lämb\nLittle", "lämb\n"]);

        // Unicode
        let mut split: Vec<&str> = data.rsplitn(3, 'ä').collect();
        split.reverse();
        assert_eq!(split, vec!["\nMäry häd ", " little l", "mb\nLittle l", "mb\n"]);

        let mut split: Vec<&str> = data.rsplitn(3, |c: char| c == 'ä').collect();
        split.reverse();
        assert_eq!(split, vec!["\nMäry häd ", " little l", "mb\nLittle l", "mb\n"]);
    }

    #[test]
    fn test_split_char_iterator_no_trailing() {
        let data = "\nMäry häd ä little lämb\nLittle lämb\n";

        let split: Vec<&str> = data.split('\n').collect();
        assert_eq!(split, vec!["", "Märy häd ä little lämb", "Little lämb", ""]);

        let split: Vec<&str> = data.split_terminator('\n').collect();
        assert_eq!(split, vec!["", "Märy häd ä little lämb", "Little lämb"]);
    }

    #[test]
    fn test_rev_split_char_iterator_no_trailing() {
        let data = "\nMäry häd ä little lämb\nLittle lämb\n";

        let mut split: Vec<&str> = data.split('\n').rev().collect();
        split.reverse();
        assert_eq!(split, vec!["", "Märy häd ä little lämb", "Little lämb", ""]);

        let mut split: Vec<&str> = data.split_terminator('\n').rev().collect();
        split.reverse();
        assert_eq!(split, vec!["", "Märy häd ä little lämb", "Little lämb"]);
    }

    #[test]
    fn test_words() {
        let data = "\n \tMäry   häd\tä  little lämb\nLittle lämb\n";
        let words: Vec<&str> = data.words().collect();
        assert_eq!(words, vec!["Märy", "häd", "ä", "little", "lämb", "Little", "lämb"])
    }

    #[test]
    fn test_nfd_chars() {
        macro_rules! t {
            ($input: expr, $expected: expr) => {
                assert_eq!($input.nfd_chars().collect::<String>(), $expected.into_string());
            }
        }
        t!("abc", "abc");
        t!("\u1e0b\u01c4", "d\u0307\u01c4");
        t!("\u2026", "\u2026");
        t!("\u2126", "\u03a9");
        t!("\u1e0b\u0323", "d\u0323\u0307");
        t!("\u1e0d\u0307", "d\u0323\u0307");
        t!("a\u0301", "a\u0301");
        t!("\u0301a", "\u0301a");
        t!("\ud4db", "\u1111\u1171\u11b6");
        t!("\uac1c", "\u1100\u1162");
    }

    #[test]
    fn test_nfkd_chars() {
        macro_rules! t {
            ($input: expr, $expected: expr) => {
                assert_eq!($input.nfkd_chars().collect::<String>(), $expected.into_string());
            }
        }
        t!("abc", "abc");
        t!("\u1e0b\u01c4", "d\u0307DZ\u030c");
        t!("\u2026", "...");
        t!("\u2126", "\u03a9");
        t!("\u1e0b\u0323", "d\u0323\u0307");
        t!("\u1e0d\u0307", "d\u0323\u0307");
        t!("a\u0301", "a\u0301");
        t!("\u0301a", "\u0301a");
        t!("\ud4db", "\u1111\u1171\u11b6");
        t!("\uac1c", "\u1100\u1162");
    }

    #[test]
    fn test_nfc_chars() {
        macro_rules! t {
            ($input: expr, $expected: expr) => {
                assert_eq!($input.nfc_chars().collect::<String>(), $expected.into_string());
            }
        }
        t!("abc", "abc");
        t!("\u1e0b\u01c4", "\u1e0b\u01c4");
        t!("\u2026", "\u2026");
        t!("\u2126", "\u03a9");
        t!("\u1e0b\u0323", "\u1e0d\u0307");
        t!("\u1e0d\u0307", "\u1e0d\u0307");
        t!("a\u0301", "\xe1");
        t!("\u0301a", "\u0301a");
        t!("\ud4db", "\ud4db");
        t!("\uac1c", "\uac1c");
        t!("a\u0300\u0305\u0315\u05aeb", "\xe0\u05ae\u0305\u0315b");
    }

    #[test]
    fn test_nfkc_chars() {
        macro_rules! t {
            ($input: expr, $expected: expr) => {
                assert_eq!($input.nfkc_chars().collect::<String>(), $expected.into_string());
            }
        }
        t!("abc", "abc");
        t!("\u1e0b\u01c4", "\u1e0bD\u017d");
        t!("\u2026", "...");
        t!("\u2126", "\u03a9");
        t!("\u1e0b\u0323", "\u1e0d\u0307");
        t!("\u1e0d\u0307", "\u1e0d\u0307");
        t!("a\u0301", "\xe1");
        t!("\u0301a", "\u0301a");
        t!("\ud4db", "\ud4db");
        t!("\uac1c", "\uac1c");
        t!("a\u0300\u0305\u0315\u05aeb", "\xe0\u05ae\u0305\u0315b");
    }

    #[test]
    fn test_lines() {
        let data = "\nMäry häd ä little lämb\n\nLittle lämb\n";
        let lines: Vec<&str> = data.lines().collect();
        assert_eq!(lines, vec!["", "Märy häd ä little lämb", "", "Little lämb"]);

        let data = "\nMäry häd ä little lämb\n\nLittle lämb"; // no trailing \n
        let lines: Vec<&str> = data.lines().collect();
        assert_eq!(lines, vec!["", "Märy häd ä little lämb", "", "Little lämb"]);
    }

    #[test]
    fn test_graphemes() {
        use std::iter::order;
        // official Unicode test data
        // from http://www.unicode.org/Public/UCD/latest/ucd/auxiliary/GraphemeBreakTest.txt
        let test_same: [(_, &[_]), .. 325] = [
            ("\u0020\u0020", &["\u0020", "\u0020"]), ("\u0020\u0308\u0020", &["\u0020\u0308",
            "\u0020"]), ("\u0020\u000D", &["\u0020", "\u000D"]), ("\u0020\u0308\u000D",
            &["\u0020\u0308", "\u000D"]), ("\u0020\u000A", &["\u0020", "\u000A"]),
            ("\u0020\u0308\u000A", &["\u0020\u0308", "\u000A"]), ("\u0020\u0001", &["\u0020",
            "\u0001"]), ("\u0020\u0308\u0001", &["\u0020\u0308", "\u0001"]), ("\u0020\u0300",
            &["\u0020\u0300"]), ("\u0020\u0308\u0300", &["\u0020\u0308\u0300"]), ("\u0020\u1100",
            &["\u0020", "\u1100"]), ("\u0020\u0308\u1100", &["\u0020\u0308", "\u1100"]),
            ("\u0020\u1160", &["\u0020", "\u1160"]), ("\u0020\u0308\u1160", &["\u0020\u0308",
            "\u1160"]), ("\u0020\u11A8", &["\u0020", "\u11A8"]), ("\u0020\u0308\u11A8",
            &["\u0020\u0308", "\u11A8"]), ("\u0020\uAC00", &["\u0020", "\uAC00"]),
            ("\u0020\u0308\uAC00", &["\u0020\u0308", "\uAC00"]), ("\u0020\uAC01", &["\u0020",
            "\uAC01"]), ("\u0020\u0308\uAC01", &["\u0020\u0308", "\uAC01"]), ("\u0020\U0001F1E6",
            &["\u0020", "\U0001F1E6"]), ("\u0020\u0308\U0001F1E6", &["\u0020\u0308",
            "\U0001F1E6"]), ("\u0020\u0378", &["\u0020", "\u0378"]), ("\u0020\u0308\u0378",
            &["\u0020\u0308", "\u0378"]), ("\u000D\u0020", &["\u000D", "\u0020"]),
            ("\u000D\u0308\u0020", &["\u000D", "\u0308", "\u0020"]), ("\u000D\u000D", &["\u000D",
            "\u000D"]), ("\u000D\u0308\u000D", &["\u000D", "\u0308", "\u000D"]), ("\u000D\u000A",
            &["\u000D\u000A"]), ("\u000D\u0308\u000A", &["\u000D", "\u0308", "\u000A"]),
            ("\u000D\u0001", &["\u000D", "\u0001"]), ("\u000D\u0308\u0001", &["\u000D", "\u0308",
            "\u0001"]), ("\u000D\u0300", &["\u000D", "\u0300"]), ("\u000D\u0308\u0300",
            &["\u000D", "\u0308\u0300"]), ("\u000D\u0903", &["\u000D", "\u0903"]),
            ("\u000D\u1100", &["\u000D", "\u1100"]), ("\u000D\u0308\u1100", &["\u000D", "\u0308",
            "\u1100"]), ("\u000D\u1160", &["\u000D", "\u1160"]), ("\u000D\u0308\u1160",
            &["\u000D", "\u0308", "\u1160"]), ("\u000D\u11A8", &["\u000D", "\u11A8"]),
            ("\u000D\u0308\u11A8", &["\u000D", "\u0308", "\u11A8"]), ("\u000D\uAC00", &["\u000D",
            "\uAC00"]), ("\u000D\u0308\uAC00", &["\u000D", "\u0308", "\uAC00"]), ("\u000D\uAC01",
            &["\u000D", "\uAC01"]), ("\u000D\u0308\uAC01", &["\u000D", "\u0308", "\uAC01"]),
            ("\u000D\U0001F1E6", &["\u000D", "\U0001F1E6"]), ("\u000D\u0308\U0001F1E6",
            &["\u000D", "\u0308", "\U0001F1E6"]), ("\u000D\u0378", &["\u000D", "\u0378"]),
            ("\u000D\u0308\u0378", &["\u000D", "\u0308", "\u0378"]), ("\u000A\u0020", &["\u000A",
            "\u0020"]), ("\u000A\u0308\u0020", &["\u000A", "\u0308", "\u0020"]), ("\u000A\u000D",
            &["\u000A", "\u000D"]), ("\u000A\u0308\u000D", &["\u000A", "\u0308", "\u000D"]),
            ("\u000A\u000A", &["\u000A", "\u000A"]), ("\u000A\u0308\u000A", &["\u000A", "\u0308",
            "\u000A"]), ("\u000A\u0001", &["\u000A", "\u0001"]), ("\u000A\u0308\u0001",
            &["\u000A", "\u0308", "\u0001"]), ("\u000A\u0300", &["\u000A", "\u0300"]),
            ("\u000A\u0308\u0300", &["\u000A", "\u0308\u0300"]), ("\u000A\u0903", &["\u000A",
            "\u0903"]), ("\u000A\u1100", &["\u000A", "\u1100"]), ("\u000A\u0308\u1100",
            &["\u000A", "\u0308", "\u1100"]), ("\u000A\u1160", &["\u000A", "\u1160"]),
            ("\u000A\u0308\u1160", &["\u000A", "\u0308", "\u1160"]), ("\u000A\u11A8", &["\u000A",
            "\u11A8"]), ("\u000A\u0308\u11A8", &["\u000A", "\u0308", "\u11A8"]), ("\u000A\uAC00",
            &["\u000A", "\uAC00"]), ("\u000A\u0308\uAC00", &["\u000A", "\u0308", "\uAC00"]),
            ("\u000A\uAC01", &["\u000A", "\uAC01"]), ("\u000A\u0308\uAC01", &["\u000A", "\u0308",
            "\uAC01"]), ("\u000A\U0001F1E6", &["\u000A", "\U0001F1E6"]),
            ("\u000A\u0308\U0001F1E6", &["\u000A", "\u0308", "\U0001F1E6"]), ("\u000A\u0378",
            &["\u000A", "\u0378"]), ("\u000A\u0308\u0378", &["\u000A", "\u0308", "\u0378"]),
            ("\u0001\u0020", &["\u0001", "\u0020"]), ("\u0001\u0308\u0020", &["\u0001", "\u0308",
            "\u0020"]), ("\u0001\u000D", &["\u0001", "\u000D"]), ("\u0001\u0308\u000D",
            &["\u0001", "\u0308", "\u000D"]), ("\u0001\u000A", &["\u0001", "\u000A"]),
            ("\u0001\u0308\u000A", &["\u0001", "\u0308", "\u000A"]), ("\u0001\u0001", &["\u0001",
            "\u0001"]), ("\u0001\u0308\u0001", &["\u0001", "\u0308", "\u0001"]), ("\u0001\u0300",
            &["\u0001", "\u0300"]), ("\u0001\u0308\u0300", &["\u0001", "\u0308\u0300"]),
            ("\u0001\u0903", &["\u0001", "\u0903"]), ("\u0001\u1100", &["\u0001", "\u1100"]),
            ("\u0001\u0308\u1100", &["\u0001", "\u0308", "\u1100"]), ("\u0001\u1160", &["\u0001",
            "\u1160"]), ("\u0001\u0308\u1160", &["\u0001", "\u0308", "\u1160"]), ("\u0001\u11A8",
            &["\u0001", "\u11A8"]), ("\u0001\u0308\u11A8", &["\u0001", "\u0308", "\u11A8"]),
            ("\u0001\uAC00", &["\u0001", "\uAC00"]), ("\u0001\u0308\uAC00", &["\u0001", "\u0308",
            "\uAC00"]), ("\u0001\uAC01", &["\u0001", "\uAC01"]), ("\u0001\u0308\uAC01",
            &["\u0001", "\u0308", "\uAC01"]), ("\u0001\U0001F1E6", &["\u0001", "\U0001F1E6"]),
            ("\u0001\u0308\U0001F1E6", &["\u0001", "\u0308", "\U0001F1E6"]), ("\u0001\u0378",
            &["\u0001", "\u0378"]), ("\u0001\u0308\u0378", &["\u0001", "\u0308", "\u0378"]),
            ("\u0300\u0020", &["\u0300", "\u0020"]), ("\u0300\u0308\u0020", &["\u0300\u0308",
            "\u0020"]), ("\u0300\u000D", &["\u0300", "\u000D"]), ("\u0300\u0308\u000D",
            &["\u0300\u0308", "\u000D"]), ("\u0300\u000A", &["\u0300", "\u000A"]),
            ("\u0300\u0308\u000A", &["\u0300\u0308", "\u000A"]), ("\u0300\u0001", &["\u0300",
            "\u0001"]), ("\u0300\u0308\u0001", &["\u0300\u0308", "\u0001"]), ("\u0300\u0300",
            &["\u0300\u0300"]), ("\u0300\u0308\u0300", &["\u0300\u0308\u0300"]), ("\u0300\u1100",
            &["\u0300", "\u1100"]), ("\u0300\u0308\u1100", &["\u0300\u0308", "\u1100"]),
            ("\u0300\u1160", &["\u0300", "\u1160"]), ("\u0300\u0308\u1160", &["\u0300\u0308",
            "\u1160"]), ("\u0300\u11A8", &["\u0300", "\u11A8"]), ("\u0300\u0308\u11A8",
            &["\u0300\u0308", "\u11A8"]), ("\u0300\uAC00", &["\u0300", "\uAC00"]),
            ("\u0300\u0308\uAC00", &["\u0300\u0308", "\uAC00"]), ("\u0300\uAC01", &["\u0300",
            "\uAC01"]), ("\u0300\u0308\uAC01", &["\u0300\u0308", "\uAC01"]), ("\u0300\U0001F1E6",
            &["\u0300", "\U0001F1E6"]), ("\u0300\u0308\U0001F1E6", &["\u0300\u0308",
            "\U0001F1E6"]), ("\u0300\u0378", &["\u0300", "\u0378"]), ("\u0300\u0308\u0378",
            &["\u0300\u0308", "\u0378"]), ("\u0903\u0020", &["\u0903", "\u0020"]),
            ("\u0903\u0308\u0020", &["\u0903\u0308", "\u0020"]), ("\u0903\u000D", &["\u0903",
            "\u000D"]), ("\u0903\u0308\u000D", &["\u0903\u0308", "\u000D"]), ("\u0903\u000A",
            &["\u0903", "\u000A"]), ("\u0903\u0308\u000A", &["\u0903\u0308", "\u000A"]),
            ("\u0903\u0001", &["\u0903", "\u0001"]), ("\u0903\u0308\u0001", &["\u0903\u0308",
            "\u0001"]), ("\u0903\u0300", &["\u0903\u0300"]), ("\u0903\u0308\u0300",
            &["\u0903\u0308\u0300"]), ("\u0903\u1100", &["\u0903", "\u1100"]),
            ("\u0903\u0308\u1100", &["\u0903\u0308", "\u1100"]), ("\u0903\u1160", &["\u0903",
            "\u1160"]), ("\u0903\u0308\u1160", &["\u0903\u0308", "\u1160"]), ("\u0903\u11A8",
            &["\u0903", "\u11A8"]), ("\u0903\u0308\u11A8", &["\u0903\u0308", "\u11A8"]),
            ("\u0903\uAC00", &["\u0903", "\uAC00"]), ("\u0903\u0308\uAC00", &["\u0903\u0308",
            "\uAC00"]), ("\u0903\uAC01", &["\u0903", "\uAC01"]), ("\u0903\u0308\uAC01",
            &["\u0903\u0308", "\uAC01"]), ("\u0903\U0001F1E6", &["\u0903", "\U0001F1E6"]),
            ("\u0903\u0308\U0001F1E6", &["\u0903\u0308", "\U0001F1E6"]), ("\u0903\u0378",
            &["\u0903", "\u0378"]), ("\u0903\u0308\u0378", &["\u0903\u0308", "\u0378"]),
            ("\u1100\u0020", &["\u1100", "\u0020"]), ("\u1100\u0308\u0020", &["\u1100\u0308",
            "\u0020"]), ("\u1100\u000D", &["\u1100", "\u000D"]), ("\u1100\u0308\u000D",
            &["\u1100\u0308", "\u000D"]), ("\u1100\u000A", &["\u1100", "\u000A"]),
            ("\u1100\u0308\u000A", &["\u1100\u0308", "\u000A"]), ("\u1100\u0001", &["\u1100",
            "\u0001"]), ("\u1100\u0308\u0001", &["\u1100\u0308", "\u0001"]), ("\u1100\u0300",
            &["\u1100\u0300"]), ("\u1100\u0308\u0300", &["\u1100\u0308\u0300"]), ("\u1100\u1100",
            &["\u1100\u1100"]), ("\u1100\u0308\u1100", &["\u1100\u0308", "\u1100"]),
            ("\u1100\u1160", &["\u1100\u1160"]), ("\u1100\u0308\u1160", &["\u1100\u0308",
            "\u1160"]), ("\u1100\u11A8", &["\u1100", "\u11A8"]), ("\u1100\u0308\u11A8",
            &["\u1100\u0308", "\u11A8"]), ("\u1100\uAC00", &["\u1100\uAC00"]),
            ("\u1100\u0308\uAC00", &["\u1100\u0308", "\uAC00"]), ("\u1100\uAC01",
            &["\u1100\uAC01"]), ("\u1100\u0308\uAC01", &["\u1100\u0308", "\uAC01"]),
            ("\u1100\U0001F1E6", &["\u1100", "\U0001F1E6"]), ("\u1100\u0308\U0001F1E6",
            &["\u1100\u0308", "\U0001F1E6"]), ("\u1100\u0378", &["\u1100", "\u0378"]),
            ("\u1100\u0308\u0378", &["\u1100\u0308", "\u0378"]), ("\u1160\u0020", &["\u1160",
            "\u0020"]), ("\u1160\u0308\u0020", &["\u1160\u0308", "\u0020"]), ("\u1160\u000D",
            &["\u1160", "\u000D"]), ("\u1160\u0308\u000D", &["\u1160\u0308", "\u000D"]),
            ("\u1160\u000A", &["\u1160", "\u000A"]), ("\u1160\u0308\u000A", &["\u1160\u0308",
            "\u000A"]), ("\u1160\u0001", &["\u1160", "\u0001"]), ("\u1160\u0308\u0001",
            &["\u1160\u0308", "\u0001"]), ("\u1160\u0300", &["\u1160\u0300"]),
            ("\u1160\u0308\u0300", &["\u1160\u0308\u0300"]), ("\u1160\u1100", &["\u1160",
            "\u1100"]), ("\u1160\u0308\u1100", &["\u1160\u0308", "\u1100"]), ("\u1160\u1160",
            &["\u1160\u1160"]), ("\u1160\u0308\u1160", &["\u1160\u0308", "\u1160"]),
            ("\u1160\u11A8", &["\u1160\u11A8"]), ("\u1160\u0308\u11A8", &["\u1160\u0308",
            "\u11A8"]), ("\u1160\uAC00", &["\u1160", "\uAC00"]), ("\u1160\u0308\uAC00",
            &["\u1160\u0308", "\uAC00"]), ("\u1160\uAC01", &["\u1160", "\uAC01"]),
            ("\u1160\u0308\uAC01", &["\u1160\u0308", "\uAC01"]), ("\u1160\U0001F1E6", &["\u1160",
            "\U0001F1E6"]), ("\u1160\u0308\U0001F1E6", &["\u1160\u0308", "\U0001F1E6"]),
            ("\u1160\u0378", &["\u1160", "\u0378"]), ("\u1160\u0308\u0378", &["\u1160\u0308",
            "\u0378"]), ("\u11A8\u0020", &["\u11A8", "\u0020"]), ("\u11A8\u0308\u0020",
            &["\u11A8\u0308", "\u0020"]), ("\u11A8\u000D", &["\u11A8", "\u000D"]),
            ("\u11A8\u0308\u000D", &["\u11A8\u0308", "\u000D"]), ("\u11A8\u000A", &["\u11A8",
            "\u000A"]), ("\u11A8\u0308\u000A", &["\u11A8\u0308", "\u000A"]), ("\u11A8\u0001",
            &["\u11A8", "\u0001"]), ("\u11A8\u0308\u0001", &["\u11A8\u0308", "\u0001"]),
            ("\u11A8\u0300", &["\u11A8\u0300"]), ("\u11A8\u0308\u0300", &["\u11A8\u0308\u0300"]),
            ("\u11A8\u1100", &["\u11A8", "\u1100"]), ("\u11A8\u0308\u1100", &["\u11A8\u0308",
            "\u1100"]), ("\u11A8\u1160", &["\u11A8", "\u1160"]), ("\u11A8\u0308\u1160",
            &["\u11A8\u0308", "\u1160"]), ("\u11A8\u11A8", &["\u11A8\u11A8"]),
            ("\u11A8\u0308\u11A8", &["\u11A8\u0308", "\u11A8"]), ("\u11A8\uAC00", &["\u11A8",
            "\uAC00"]), ("\u11A8\u0308\uAC00", &["\u11A8\u0308", "\uAC00"]), ("\u11A8\uAC01",
            &["\u11A8", "\uAC01"]), ("\u11A8\u0308\uAC01", &["\u11A8\u0308", "\uAC01"]),
            ("\u11A8\U0001F1E6", &["\u11A8", "\U0001F1E6"]), ("\u11A8\u0308\U0001F1E6",
            &["\u11A8\u0308", "\U0001F1E6"]), ("\u11A8\u0378", &["\u11A8", "\u0378"]),
            ("\u11A8\u0308\u0378", &["\u11A8\u0308", "\u0378"]), ("\uAC00\u0020", &["\uAC00",
            "\u0020"]), ("\uAC00\u0308\u0020", &["\uAC00\u0308", "\u0020"]), ("\uAC00\u000D",
            &["\uAC00", "\u000D"]), ("\uAC00\u0308\u000D", &["\uAC00\u0308", "\u000D"]),
            ("\uAC00\u000A", &["\uAC00", "\u000A"]), ("\uAC00\u0308\u000A", &["\uAC00\u0308",
            "\u000A"]), ("\uAC00\u0001", &["\uAC00", "\u0001"]), ("\uAC00\u0308\u0001",
            &["\uAC00\u0308", "\u0001"]), ("\uAC00\u0300", &["\uAC00\u0300"]),
            ("\uAC00\u0308\u0300", &["\uAC00\u0308\u0300"]), ("\uAC00\u1100", &["\uAC00",
            "\u1100"]), ("\uAC00\u0308\u1100", &["\uAC00\u0308", "\u1100"]), ("\uAC00\u1160",
            &["\uAC00\u1160"]), ("\uAC00\u0308\u1160", &["\uAC00\u0308", "\u1160"]),
            ("\uAC00\u11A8", &["\uAC00\u11A8"]), ("\uAC00\u0308\u11A8", &["\uAC00\u0308",
            "\u11A8"]), ("\uAC00\uAC00", &["\uAC00", "\uAC00"]), ("\uAC00\u0308\uAC00",
            &["\uAC00\u0308", "\uAC00"]), ("\uAC00\uAC01", &["\uAC00", "\uAC01"]),
            ("\uAC00\u0308\uAC01", &["\uAC00\u0308", "\uAC01"]), ("\uAC00\U0001F1E6", &["\uAC00",
            "\U0001F1E6"]), ("\uAC00\u0308\U0001F1E6", &["\uAC00\u0308", "\U0001F1E6"]),
            ("\uAC00\u0378", &["\uAC00", "\u0378"]), ("\uAC00\u0308\u0378", &["\uAC00\u0308",
            "\u0378"]), ("\uAC01\u0020", &["\uAC01", "\u0020"]), ("\uAC01\u0308\u0020",
            &["\uAC01\u0308", "\u0020"]), ("\uAC01\u000D", &["\uAC01", "\u000D"]),
            ("\uAC01\u0308\u000D", &["\uAC01\u0308", "\u000D"]), ("\uAC01\u000A", &["\uAC01",
            "\u000A"]), ("\uAC01\u0308\u000A", &["\uAC01\u0308", "\u000A"]), ("\uAC01\u0001",
            &["\uAC01", "\u0001"]), ("\uAC01\u0308\u0001", &["\uAC01\u0308", "\u0001"]),
            ("\uAC01\u0300", &["\uAC01\u0300"]), ("\uAC01\u0308\u0300", &["\uAC01\u0308\u0300"]),
            ("\uAC01\u1100", &["\uAC01", "\u1100"]), ("\uAC01\u0308\u1100", &["\uAC01\u0308",
            "\u1100"]), ("\uAC01\u1160", &["\uAC01", "\u1160"]), ("\uAC01\u0308\u1160",
            &["\uAC01\u0308", "\u1160"]), ("\uAC01\u11A8", &["\uAC01\u11A8"]),
            ("\uAC01\u0308\u11A8", &["\uAC01\u0308", "\u11A8"]), ("\uAC01\uAC00", &["\uAC01",
            "\uAC00"]), ("\uAC01\u0308\uAC00", &["\uAC01\u0308", "\uAC00"]), ("\uAC01\uAC01",
            &["\uAC01", "\uAC01"]), ("\uAC01\u0308\uAC01", &["\uAC01\u0308", "\uAC01"]),
            ("\uAC01\U0001F1E6", &["\uAC01", "\U0001F1E6"]), ("\uAC01\u0308\U0001F1E6",
            &["\uAC01\u0308", "\U0001F1E6"]), ("\uAC01\u0378", &["\uAC01", "\u0378"]),
            ("\uAC01\u0308\u0378", &["\uAC01\u0308", "\u0378"]), ("\U0001F1E6\u0020",
            &["\U0001F1E6", "\u0020"]), ("\U0001F1E6\u0308\u0020", &["\U0001F1E6\u0308",
            "\u0020"]), ("\U0001F1E6\u000D", &["\U0001F1E6", "\u000D"]),
            ("\U0001F1E6\u0308\u000D", &["\U0001F1E6\u0308", "\u000D"]), ("\U0001F1E6\u000A",
            &["\U0001F1E6", "\u000A"]), ("\U0001F1E6\u0308\u000A", &["\U0001F1E6\u0308",
            "\u000A"]), ("\U0001F1E6\u0001", &["\U0001F1E6", "\u0001"]),
            ("\U0001F1E6\u0308\u0001", &["\U0001F1E6\u0308", "\u0001"]), ("\U0001F1E6\u0300",
            &["\U0001F1E6\u0300"]), ("\U0001F1E6\u0308\u0300", &["\U0001F1E6\u0308\u0300"]),
            ("\U0001F1E6\u1100", &["\U0001F1E6", "\u1100"]), ("\U0001F1E6\u0308\u1100",
            &["\U0001F1E6\u0308", "\u1100"]), ("\U0001F1E6\u1160", &["\U0001F1E6", "\u1160"]),
            ("\U0001F1E6\u0308\u1160", &["\U0001F1E6\u0308", "\u1160"]), ("\U0001F1E6\u11A8",
            &["\U0001F1E6", "\u11A8"]), ("\U0001F1E6\u0308\u11A8", &["\U0001F1E6\u0308",
            "\u11A8"]), ("\U0001F1E6\uAC00", &["\U0001F1E6", "\uAC00"]),
            ("\U0001F1E6\u0308\uAC00", &["\U0001F1E6\u0308", "\uAC00"]), ("\U0001F1E6\uAC01",
            &["\U0001F1E6", "\uAC01"]), ("\U0001F1E6\u0308\uAC01", &["\U0001F1E6\u0308",
            "\uAC01"]), ("\U0001F1E6\U0001F1E6", &["\U0001F1E6\U0001F1E6"]),
            ("\U0001F1E6\u0308\U0001F1E6", &["\U0001F1E6\u0308", "\U0001F1E6"]),
            ("\U0001F1E6\u0378", &["\U0001F1E6", "\u0378"]), ("\U0001F1E6\u0308\u0378",
            &["\U0001F1E6\u0308", "\u0378"]), ("\u0378\u0020", &["\u0378", "\u0020"]),
            ("\u0378\u0308\u0020", &["\u0378\u0308", "\u0020"]), ("\u0378\u000D", &["\u0378",
            "\u000D"]), ("\u0378\u0308\u000D", &["\u0378\u0308", "\u000D"]), ("\u0378\u000A",
            &["\u0378", "\u000A"]), ("\u0378\u0308\u000A", &["\u0378\u0308", "\u000A"]),
            ("\u0378\u0001", &["\u0378", "\u0001"]), ("\u0378\u0308\u0001", &["\u0378\u0308",
            "\u0001"]), ("\u0378\u0300", &["\u0378\u0300"]), ("\u0378\u0308\u0300",
            &["\u0378\u0308\u0300"]), ("\u0378\u1100", &["\u0378", "\u1100"]),
            ("\u0378\u0308\u1100", &["\u0378\u0308", "\u1100"]), ("\u0378\u1160", &["\u0378",
            "\u1160"]), ("\u0378\u0308\u1160", &["\u0378\u0308", "\u1160"]), ("\u0378\u11A8",
            &["\u0378", "\u11A8"]), ("\u0378\u0308\u11A8", &["\u0378\u0308", "\u11A8"]),
            ("\u0378\uAC00", &["\u0378", "\uAC00"]), ("\u0378\u0308\uAC00", &["\u0378\u0308",
            "\uAC00"]), ("\u0378\uAC01", &["\u0378", "\uAC01"]), ("\u0378\u0308\uAC01",
            &["\u0378\u0308", "\uAC01"]), ("\u0378\U0001F1E6", &["\u0378", "\U0001F1E6"]),
            ("\u0378\u0308\U0001F1E6", &["\u0378\u0308", "\U0001F1E6"]), ("\u0378\u0378",
            &["\u0378", "\u0378"]), ("\u0378\u0308\u0378", &["\u0378\u0308", "\u0378"]),
            ("\u0061\U0001F1E6\u0062", &["\u0061", "\U0001F1E6", "\u0062"]),
            ("\U0001F1F7\U0001F1FA", &["\U0001F1F7\U0001F1FA"]),
            ("\U0001F1F7\U0001F1FA\U0001F1F8", &["\U0001F1F7\U0001F1FA\U0001F1F8"]),
            ("\U0001F1F7\U0001F1FA\U0001F1F8\U0001F1EA",
            &["\U0001F1F7\U0001F1FA\U0001F1F8\U0001F1EA"]),
            ("\U0001F1F7\U0001F1FA\u200B\U0001F1F8\U0001F1EA", &["\U0001F1F7\U0001F1FA", "\u200B",
            "\U0001F1F8\U0001F1EA"]), ("\U0001F1E6\U0001F1E7\U0001F1E8",
            &["\U0001F1E6\U0001F1E7\U0001F1E8"]), ("\U0001F1E6\u200D\U0001F1E7\U0001F1E8",
            &["\U0001F1E6\u200D", "\U0001F1E7\U0001F1E8"]),
            ("\U0001F1E6\U0001F1E7\u200D\U0001F1E8", &["\U0001F1E6\U0001F1E7\u200D",
            "\U0001F1E8"]), ("\u0020\u200D\u0646", &["\u0020\u200D", "\u0646"]),
            ("\u0646\u200D\u0020", &["\u0646\u200D", "\u0020"]),
        ];

        let test_diff: [(_, &[_], &[_]), .. 23] = [
            ("\u0020\u0903", &["\u0020\u0903"], &["\u0020", "\u0903"]), ("\u0020\u0308\u0903",
            &["\u0020\u0308\u0903"], &["\u0020\u0308", "\u0903"]), ("\u000D\u0308\u0903",
            &["\u000D", "\u0308\u0903"], &["\u000D", "\u0308", "\u0903"]), ("\u000A\u0308\u0903",
            &["\u000A", "\u0308\u0903"], &["\u000A", "\u0308", "\u0903"]), ("\u0001\u0308\u0903",
            &["\u0001", "\u0308\u0903"], &["\u0001", "\u0308", "\u0903"]), ("\u0300\u0903",
            &["\u0300\u0903"], &["\u0300", "\u0903"]), ("\u0300\u0308\u0903",
            &["\u0300\u0308\u0903"], &["\u0300\u0308", "\u0903"]), ("\u0903\u0903",
            &["\u0903\u0903"], &["\u0903", "\u0903"]), ("\u0903\u0308\u0903",
            &["\u0903\u0308\u0903"], &["\u0903\u0308", "\u0903"]), ("\u1100\u0903",
            &["\u1100\u0903"], &["\u1100", "\u0903"]), ("\u1100\u0308\u0903",
            &["\u1100\u0308\u0903"], &["\u1100\u0308", "\u0903"]), ("\u1160\u0903",
            &["\u1160\u0903"], &["\u1160", "\u0903"]), ("\u1160\u0308\u0903",
            &["\u1160\u0308\u0903"], &["\u1160\u0308", "\u0903"]), ("\u11A8\u0903",
            &["\u11A8\u0903"], &["\u11A8", "\u0903"]), ("\u11A8\u0308\u0903",
            &["\u11A8\u0308\u0903"], &["\u11A8\u0308", "\u0903"]), ("\uAC00\u0903",
            &["\uAC00\u0903"], &["\uAC00", "\u0903"]), ("\uAC00\u0308\u0903",
            &["\uAC00\u0308\u0903"], &["\uAC00\u0308", "\u0903"]), ("\uAC01\u0903",
            &["\uAC01\u0903"], &["\uAC01", "\u0903"]), ("\uAC01\u0308\u0903",
            &["\uAC01\u0308\u0903"], &["\uAC01\u0308", "\u0903"]), ("\U0001F1E6\u0903",
            &["\U0001F1E6\u0903"], &["\U0001F1E6", "\u0903"]), ("\U0001F1E6\u0308\u0903",
            &["\U0001F1E6\u0308\u0903"], &["\U0001F1E6\u0308", "\u0903"]), ("\u0378\u0903",
            &["\u0378\u0903"], &["\u0378", "\u0903"]), ("\u0378\u0308\u0903",
            &["\u0378\u0308\u0903"], &["\u0378\u0308", "\u0903"]),
        ];

        for &(s, g) in test_same.iter() {
            // test forward iterator
            assert!(order::equals(s.graphemes(true), g.iter().map(|&x| x)));
            assert!(order::equals(s.graphemes(false), g.iter().map(|&x| x)));

            // test reverse iterator
            assert!(order::equals(s.graphemes(true).rev(), g.iter().rev().map(|&x| x)));
            assert!(order::equals(s.graphemes(false).rev(), g.iter().rev().map(|&x| x)));
        }

        for &(s, gt, gf) in test_diff.iter() {
            // test forward iterator
            assert!(order::equals(s.graphemes(true), gt.iter().map(|&x| x)));
            assert!(order::equals(s.graphemes(false), gf.iter().map(|&x| x)));

            // test reverse iterator
            assert!(order::equals(s.graphemes(true).rev(), gt.iter().rev().map(|&x| x)));
            assert!(order::equals(s.graphemes(false).rev(), gf.iter().rev().map(|&x| x)));
        }

        // test the indices iterators
        let s = "a̐éö̲\r\n";
        let gr_inds = s.grapheme_indices(true).collect::<Vec<(uint, &str)>>();
        let b: &[_] = &[(0u, "a̐"), (3, "é"), (6, "ö̲"), (11, "\r\n")];
        assert_eq!(gr_inds.as_slice(), b);
        let gr_inds = s.grapheme_indices(true).rev().collect::<Vec<(uint, &str)>>();
        let b: &[_] = &[(11, "\r\n"), (6, "ö̲"), (3, "é"), (0u, "a̐")];
        assert_eq!(gr_inds.as_slice(), b);
        let mut gr_inds = s.grapheme_indices(true);
        let e1 = gr_inds.size_hint();
        assert_eq!(e1, (1, Some(13)));
        let c = gr_inds.count();
        assert_eq!(c, 4);
        let e2 = gr_inds.size_hint();
        assert_eq!(e2, (0, Some(0)));

        // make sure the reverse iterator does the right thing with "\n" at beginning of string
        let s = "\n\r\n\r";
        let gr = s.graphemes(true).rev().collect::<Vec<&str>>();
        let b: &[_] = &["\r", "\r\n", "\n"];
        assert_eq!(gr.as_slice(), b);
    }

    #[test]
    fn test_split_strator() {
        fn t(s: &str, sep: &str, u: &[&str]) {
            let v: Vec<&str> = s.split_str(sep).collect();
            assert_eq!(v.as_slice(), u.as_slice());
        }
        t("--1233345--", "12345", ["--1233345--"]);
        t("abc::hello::there", "::", ["abc", "hello", "there"]);
        t("::hello::there", "::", ["", "hello", "there"]);
        t("hello::there::", "::", ["hello", "there", ""]);
        t("::hello::there::", "::", ["", "hello", "there", ""]);
        t("ประเทศไทย中华Việt Nam", "中华", ["ประเทศไทย", "Việt Nam"]);
        t("zzXXXzzYYYzz", "zz", ["", "XXX", "YYY", ""]);
        t("zzXXXzYYYz", "XXX", ["zz", "zYYYz"]);
        t(".XXX.YYY.", ".", ["", "XXX", "YYY", ""]);
        t("", ".", [""]);
        t("zz", "zz", ["",""]);
        t("ok", "z", ["ok"]);
        t("zzz", "zz", ["","z"]);
        t("zzzzz", "zz", ["","","z"]);
    }

    #[test]
    fn test_str_default() {
        use std::default::Default;
        fn t<S: Default + Str>() {
            let s: S = Default::default();
            assert_eq!(s.as_slice(), "");
        }

        t::<&str>();
        t::<String>();
    }

    #[test]
    fn test_str_container() {
        fn sum_len<S: Collection>(v: &[S]) -> uint {
            v.iter().map(|x| x.len()).sum()
        }

        let s = String::from_str("01234");
        assert_eq!(5, sum_len(["012", "", "34"]));
        assert_eq!(5, sum_len([String::from_str("01"), String::from_str("2"),
                               String::from_str("34"), String::from_str("")]));
        assert_eq!(5, sum_len([s.as_slice()]));
    }

    #[test]
    fn test_str_from_utf8() {
        let xs = b"hello";
        assert_eq!(from_utf8(xs), Some("hello"));

        let xs = "ศไทย中华Việt Nam".as_bytes();
        assert_eq!(from_utf8(xs), Some("ศไทย中华Việt Nam"));

        let xs = b"hello\xFF";
        assert_eq!(from_utf8(xs), None);
    }

    #[test]
    fn test_maybe_owned_traits() {
        let s = Slice("abcde");
        assert_eq!(s.len(), 5);
        assert_eq!(s.as_slice(), "abcde");
        assert_eq!(String::from_str(s.as_slice()).as_slice(), "abcde");
        assert_eq!(format!("{}", s).as_slice(), "abcde");
        assert!(s.lt(&Owned(String::from_str("bcdef"))));
        assert_eq!(Slice(""), Default::default());

        let o = Owned(String::from_str("abcde"));
        assert_eq!(o.len(), 5);
        assert_eq!(o.as_slice(), "abcde");
        assert_eq!(String::from_str(o.as_slice()).as_slice(), "abcde");
        assert_eq!(format!("{}", o).as_slice(), "abcde");
        assert!(o.lt(&Slice("bcdef")));
        assert_eq!(Owned(String::from_str("")), Default::default());

        assert!(s.cmp(&o) == Equal);
        assert!(s.equiv(&o));

        assert!(o.cmp(&s) == Equal);
        assert!(o.equiv(&s));
    }

    #[test]
    fn test_maybe_owned_methods() {
        let s = Slice("abcde");
        assert!(s.is_slice());
        assert!(!s.is_owned());

        let o = Owned(String::from_str("abcde"));
        assert!(!o.is_slice());
        assert!(o.is_owned());
    }

    #[test]
    fn test_maybe_owned_clone() {
        assert_eq!(Owned(String::from_str("abcde")), Slice("abcde").clone());
        assert_eq!(Owned(String::from_str("abcde")), Owned(String::from_str("abcde")).clone());
        assert_eq!(Slice("abcde"), Slice("abcde").clone());
        assert_eq!(Slice("abcde"), Owned(String::from_str("abcde")).clone());
    }

    #[test]
    fn test_maybe_owned_into_string() {
        assert_eq!(Slice("abcde").into_string(), String::from_str("abcde"));
        assert_eq!(Owned(String::from_str("abcde")).into_string(),
                   String::from_str("abcde"));
    }

    #[test]
    fn test_into_maybe_owned() {
        assert_eq!("abcde".into_maybe_owned(), Slice("abcde"));
        assert_eq!((String::from_str("abcde")).into_maybe_owned(), Slice("abcde"));
        assert_eq!("abcde".into_maybe_owned(), Owned(String::from_str("abcde")));
        assert_eq!((String::from_str("abcde")).into_maybe_owned(),
                   Owned(String::from_str("abcde")));
    }
}

#[cfg(test)]
mod bench {
    use test::Bencher;
    use test::black_box;
    use super::*;
    use std::option::{None, Some};
    use std::iter::{Iterator, DoubleEndedIterator};
    use std::collections::Collection;

    #[bench]
    fn char_iterator(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";

        b.iter(|| s.chars().count());
    }

    #[bench]
    fn char_iterator_for(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";

        b.iter(|| {
            for ch in s.chars() { black_box(ch) }
        });
    }

    #[bench]
    fn char_iterator_ascii(b: &mut Bencher) {
        let s = "Mary had a little lamb, Little lamb
        Mary had a little lamb, Little lamb
        Mary had a little lamb, Little lamb
        Mary had a little lamb, Little lamb
        Mary had a little lamb, Little lamb
        Mary had a little lamb, Little lamb";

        b.iter(|| s.chars().count());
    }

    #[bench]
    fn char_iterator_rev(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";

        b.iter(|| s.chars().rev().count());
    }

    #[bench]
    fn char_iterator_rev_for(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";

        b.iter(|| {
            for ch in s.chars().rev() { black_box(ch) }
        });
    }

    #[bench]
    fn char_indicesator(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";
        let len = s.char_len();

        b.iter(|| assert_eq!(s.char_indices().count(), len));
    }

    #[bench]
    fn char_indicesator_rev(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";
        let len = s.char_len();

        b.iter(|| assert_eq!(s.char_indices().rev().count(), len));
    }

    #[bench]
    fn split_unicode_ascii(b: &mut Bencher) {
        let s = "ประเทศไทย中华Việt Namประเทศไทย中华Việt Nam";

        b.iter(|| assert_eq!(s.split('V').count(), 3));
    }

    #[bench]
    fn split_unicode_not_ascii(b: &mut Bencher) {
        struct NotAscii(char);
        impl CharEq for NotAscii {
            fn matches(&mut self, c: char) -> bool {
                let NotAscii(cc) = *self;
                cc == c
            }
            fn only_ascii(&self) -> bool { false }
        }
        let s = "ประเทศไทย中华Việt Namประเทศไทย中华Việt Nam";

        b.iter(|| assert_eq!(s.split(NotAscii('V')).count(), 3));
    }


    #[bench]
    fn split_ascii(b: &mut Bencher) {
        let s = "Mary had a little lamb, Little lamb, little-lamb.";
        let len = s.split(' ').count();

        b.iter(|| assert_eq!(s.split(' ').count(), len));
    }

    #[bench]
    fn split_not_ascii(b: &mut Bencher) {
        struct NotAscii(char);
        impl CharEq for NotAscii {
            #[inline]
            fn matches(&mut self, c: char) -> bool {
                let NotAscii(cc) = *self;
                cc == c
            }
            fn only_ascii(&self) -> bool { false }
        }
        let s = "Mary had a little lamb, Little lamb, little-lamb.";
        let len = s.split(' ').count();

        b.iter(|| assert_eq!(s.split(NotAscii(' ')).count(), len));
    }

    #[bench]
    fn split_extern_fn(b: &mut Bencher) {
        let s = "Mary had a little lamb, Little lamb, little-lamb.";
        let len = s.split(' ').count();
        fn pred(c: char) -> bool { c == ' ' }

        b.iter(|| assert_eq!(s.split(pred).count(), len));
    }

    #[bench]
    fn split_closure(b: &mut Bencher) {
        let s = "Mary had a little lamb, Little lamb, little-lamb.";
        let len = s.split(' ').count();

        b.iter(|| assert_eq!(s.split(|c: char| c == ' ').count(), len));
    }

    #[bench]
    fn split_slice(b: &mut Bencher) {
        let s = "Mary had a little lamb, Little lamb, little-lamb.";
        let len = s.split(' ').count();

        let c: &[char] = &[' '];
        b.iter(|| assert_eq!(s.split(c).count(), len));
    }

    #[bench]
    fn is_utf8_100_ascii(b: &mut Bencher) {

        let s = b"Hello there, the quick brown fox jumped over the lazy dog! \
                  Lorem ipsum dolor sit amet, consectetur. ";

        assert_eq!(100, s.len());
        b.iter(|| {
            is_utf8(s)
        });
    }

    #[bench]
    fn is_utf8_100_multibyte(b: &mut Bencher) {
        let s = "𐌀𐌖𐌋𐌄𐌑𐌉ปรدولة الكويتทศไทย中华𐍅𐌿𐌻𐍆𐌹𐌻𐌰".as_bytes();
        assert_eq!(100, s.len());
        b.iter(|| {
            is_utf8(s)
        });
    }

    #[bench]
    fn bench_connect(b: &mut Bencher) {
        let s = "ศไทย中华Việt Nam; Mary had a little lamb, Little lamb";
        let sep = "→";
        let v = [s, s, s, s, s, s, s, s, s, s];
        b.iter(|| {
            assert_eq!(v.connect(sep).len(), s.len() * 10 + sep.len() * 9);
        })
    }

    #[bench]
    fn bench_contains_short_short(b: &mut Bencher) {
        let haystack = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
        let needle = "sit";

        b.iter(|| {
            assert!(haystack.contains(needle));
        })
    }

    #[bench]
    fn bench_contains_short_long(b: &mut Bencher) {
        let haystack = "\
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse quis lorem sit amet dolor \
ultricies condimentum. Praesent iaculis purus elit, ac malesuada quam malesuada in. Duis sed orci \
eros. Suspendisse sit amet magna mollis, mollis nunc luctus, imperdiet mi. Integer fringilla non \
sem ut lacinia. Fusce varius tortor a risus porttitor hendrerit. Morbi mauris dui, ultricies nec \
tempus vel, gravida nec quam.

In est dui, tincidunt sed tempus interdum, adipiscing laoreet ante. Etiam tempor, tellus quis \
sagittis interdum, nulla purus mattis sem, quis auctor erat odio ac tellus. In nec nunc sit amet \
diam volutpat molestie at sed ipsum. Vestibulum laoreet consequat vulputate. Integer accumsan \
lorem ac dignissim placerat. Suspendisse convallis faucibus lorem. Aliquam erat volutpat. In vel \
eleifend felis. Sed suscipit nulla lorem, sed mollis est sollicitudin et. Nam fermentum egestas \
interdum. Curabitur ut nisi justo.

Sed sollicitudin ipsum tellus, ut condimentum leo eleifend nec. Cras ut velit ante. Phasellus nec \
mollis odio. Mauris molestie erat in arcu mattis, at aliquet dolor vehicula. Quisque malesuada \
lectus sit amet nisi pretium, a condimentum ipsum porta. Morbi at dapibus diam. Praesent egestas \
est sed risus elementum, eu rutrum metus ultrices. Etiam fermentum consectetur magna, id rutrum \
felis accumsan a. Aliquam ut pellentesque libero. Sed mi nulla, lobortis eu tortor id, suscipit \
ultricies neque. Morbi iaculis sit amet risus at iaculis. Praesent eget ligula quis turpis \
feugiat suscipit vel non arcu. Interdum et malesuada fames ac ante ipsum primis in faucibus. \
Aliquam sit amet placerat lorem.

Cras a lacus vel ante posuere elementum. Nunc est leo, bibendum ut facilisis vel, bibendum at \
mauris. Nullam adipiscing diam vel odio ornare, luctus adipiscing mi luctus. Nulla facilisi. \
Mauris adipiscing bibendum neque, quis adipiscing lectus tempus et. Sed feugiat erat et nisl \
lobortis pharetra. Donec vitae erat enim. Nullam sit amet felis et quam lacinia tincidunt. Aliquam \
suscipit dapibus urna. Sed volutpat urna in magna pulvinar volutpat. Phasellus nec tellus ac diam \
cursus accumsan.

Nam lectus enim, dapibus non nisi tempor, consectetur convallis massa. Maecenas eleifend dictum \
feugiat. Etiam quis mauris vel risus luctus mattis a a nunc. Nullam orci quam, imperdiet id \
vehicula in, porttitor ut nibh. Duis sagittis adipiscing nisl vitae congue. Donec mollis risus eu \
leo suscipit, varius porttitor nulla porta. Pellentesque ut sem nec nisi euismod vehicula. Nulla \
malesuada sollicitudin quam eu fermentum.";
        let needle = "english";

        b.iter(|| {
            assert!(!haystack.contains(needle));
        })
    }

    #[bench]
    fn bench_contains_bad_naive(b: &mut Bencher) {
        let haystack = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
        let needle = "aaaaaaaab";

        b.iter(|| {
            assert!(!haystack.contains(needle));
        })
    }

    #[bench]
    fn bench_contains_equal(b: &mut Bencher) {
        let haystack = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
        let needle = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";

        b.iter(|| {
            assert!(haystack.contains(needle));
        })
    }
}