src/libstd_unicode/u_str.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Unicode-intensive string manipulations.
  12 //!
  13 //! This module provides functionality to `str` that requires the Unicode
  14 //! methods provided by the unicode parts of the CharExt trait.
  15
  16 use core::char;
  17 use core::iter::{Filter, FusedIterator};
  18 use core::str::Split;
  19
  20 /// An iterator over the non-whitespace substrings of a string,
  21 /// separated by any amount of whitespace.
  22 ///
  23 /// This struct is created by the [`split_whitespace`] method on [`str`].
  24 /// See its documentation for more.
  25 ///
  26 /// [`split_whitespace`]: ../../std/primitive.str.html#method.split_whitespace
  27 /// [`str`]: ../../std/primitive.str.html
  28 #[stable(feature = "split_whitespace", since = "1.1.0")]
  29 #[derive(Clone)]
  30 pub struct SplitWhitespace<'a> {
  31     inner: Filter<Split<'a, IsWhitespace>, IsNotEmpty>,
  32 }
  33
  34 /// Methods for Unicode string slices
  35 #[allow(missing_docs)] // docs in libcollections
  36 pub trait UnicodeStr {
  37     fn split_whitespace<'a>(&'a self) -> SplitWhitespace<'a>;
  38     fn is_whitespace(&self) -> bool;
  39     fn is_alphanumeric(&self) -> bool;
  40     fn trim(&self) -> &str;
  41     fn trim_left(&self) -> &str;
  42     fn trim_right(&self) -> &str;
  43 }
  44
  45 impl UnicodeStr for str {
  46     #[inline]
  47     fn split_whitespace(&self) -> SplitWhitespace {
  48         SplitWhitespace { inner: self.split(IsWhitespace).filter(IsNotEmpty) }
  49     }
  50
  51     #[inline]
  52     fn is_whitespace(&self) -> bool {
  53         self.chars().all(|c| c.is_whitespace())
  54     }
  55
  56     #[inline]
  57     fn is_alphanumeric(&self) -> bool {
  58         self.chars().all(|c| c.is_alphanumeric())
  59     }
  60
  61     #[inline]
  62     fn trim(&self) -> &str {
  63         self.trim_matches(|c: char| c.is_whitespace())
  64     }
  65
  66     #[inline]
  67     fn trim_left(&self) -> &str {
  68         self.trim_left_matches(|c: char| c.is_whitespace())
  69     }
  70
  71     #[inline]
  72     fn trim_right(&self) -> &str {
  73         self.trim_right_matches(|c: char| c.is_whitespace())
  74     }
  75 }
  76
  77 /// Iterator adaptor for encoding `char`s to UTF-16.
  78 #[derive(Clone)]
  79 pub struct Utf16Encoder<I> {
  80     chars: I,
  81     extra: u16,
  82 }
  83
  84 impl<I> Utf16Encoder<I> {
  85     /// Create a UTF-16 encoder from any `char` iterator.
  86     pub fn new(chars: I) -> Utf16Encoder<I>
  87         where I: Iterator<Item = char>
  88     {
  89         Utf16Encoder {
  90             chars: chars,
  91             extra: 0,
  92         }
  93     }
  94 }
  95
  96 impl<I> Iterator for Utf16Encoder<I>
  97     where I: Iterator<Item = char>
  98 {
  99     type Item = u16;
 100
 101     #[inline]
 102     fn next(&mut self) -> Option<u16> {
 103         if self.extra != 0 {
 104             let tmp = self.extra;
 105             self.extra = 0;
 106             return Some(tmp);
 107         }
 108
 109         let mut buf = [0; 2];
 110         self.chars.next().map(|ch| {
 111             let n = CharExt::encode_utf16(ch, &mut buf).len();
 112             if n == 2 {
 113                 self.extra = buf[1];
 114             }
 115             buf[0]
 116         })
 117     }
 118
 119     #[inline]
 120     fn size_hint(&self) -> (usize, Option<usize>) {
 121         let (low, high) = self.chars.size_hint();
 122         // every char gets either one u16 or two u16,
 123         // so this iterator is between 1 or 2 times as
 124         // long as the underlying iterator.
 125         (low, high.and_then(|n| n.checked_mul(2)))
 126     }
 127 }
 128
 129 #[unstable(feature = "fused", issue = "35602")]
 130 impl<I> FusedIterator for Utf16Encoder<I>
 131     where I: FusedIterator<Item = char> {}
 132
 133 #[derive(Clone)]
 134 struct IsWhitespace;
 135
 136 impl FnOnce<(char, )> for IsWhitespace {
 137     type Output = bool;
 138
 139     #[inline]
 140     extern "rust-call" fn call_once(mut self, arg: (char, )) -> bool {
 141         self.call_mut(arg)
 142     }
 143 }
 144
 145 impl FnMut<(char, )> for IsWhitespace {
 146     #[inline]
 147     extern "rust-call" fn call_mut(&mut self, arg: (char, )) -> bool {
 148         arg.0.is_whitespace()
 149     }
 150 }
 151
 152 #[derive(Clone)]
 153 struct IsNotEmpty;
 154
 155 impl<'a, 'b> FnOnce<(&'a &'b str, )> for IsNotEmpty {
 156     type Output = bool;
 157
 158     #[inline]
 159     extern "rust-call" fn call_once(mut self, arg: (&&str, )) -> bool {
 160         self.call_mut(arg)
 161     }
 162 }
 163
 164 impl<'a, 'b> FnMut<(&'a &'b str, )> for IsNotEmpty {
 165     #[inline]
 166     extern "rust-call" fn call_mut(&mut self, arg: (&&str, )) -> bool {
 167         !arg.0.is_empty()
 168     }
 169 }
 170
 171
 172 #[stable(feature = "split_whitespace", since = "1.1.0")]
 173 impl<'a> Iterator for SplitWhitespace<'a> {
 174     type Item = &'a str;
 175
 176     fn next(&mut self) -> Option<&'a str> {
 177         self.inner.next()
 178     }
 179 }
 180
 181 #[stable(feature = "split_whitespace", since = "1.1.0")]
 182 impl<'a> DoubleEndedIterator for SplitWhitespace<'a> {
 183     fn next_back(&mut self) -> Option<&'a str> {
 184         self.inner.next_back()
 185     }
 186 }
 187
 188 #[unstable(feature = "fused", issue = "35602")]
 189 impl<'a> FusedIterator for SplitWhitespace<'a> {}