aboutsummaryrefslogtreecommitdiff
path: root/textwrap/src/lib.rs
blob: 2f82325fbc2ef4b22eb61727aaaed5c9483f7a8b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
//! `textwrap` provides functions for word wrapping and filling text.
//!
//! Wrapping text can be very useful in commandline programs where you
//! want to format dynamic output nicely so it looks good in a
//! terminal. A quick example:
//!
//! ```no_run
//! extern crate textwrap;
//! use textwrap::fill;
//!
//! fn main() {
//!     let text = "textwrap: a small library for wrapping text.";
//!     println!("{}", fill(text, 18));
//! }
//! ```
//!
//! This will display the following output:
//!
//! ```text
//! textwrap: a small
//! library for
//! wrapping text.
//! ```
//!
//! # Displayed Width vs Byte Size
//!
//! To word wrap text, one must know the width of each word so one can
//! know when to break lines. This library measures the width of text
//! using the [displayed width][unicode-width], not the size in bytes.
//!
//! This is important for non-ASCII text. ASCII characters such as `a`
//! and `!` are simple and take up one column each. This means that
//! the displayed width is equal to the string length in bytes.
//! However, non-ASCII characters and symbols take up more than one
//! byte when UTF-8 encoded: `é` is `0xc3 0xa9` (two bytes) and `⚙` is
//! `0xe2 0x9a 0x99` (three bytes) in UTF-8, respectively.
//!
//! This is why we take care to use the displayed width instead of the
//! byte count when computing line lengths. All functions in this
//! library handle Unicode characters like this.
//!
//! [unicode-width]: https://docs.rs/unicode-width/

#![doc(html_root_url = "https://docs.rs/textwrap/0.11.0")]
#![deny(missing_docs)]
#![deny(missing_debug_implementations)]

#[cfg(feature = "hyphenation")]
extern crate hyphenation;
#[cfg(feature = "term_size")]
extern crate term_size;
extern crate unicode_width;

use std::borrow::Cow;
use std::str::CharIndices;

use unicode_width::UnicodeWidthChar;
use unicode_width::UnicodeWidthStr;

/// A non-breaking space.
const NBSP: char = '\u{a0}';

mod indentation;
pub use indentation::dedent;
pub use indentation::indent;

mod splitting;
pub use splitting::{HyphenSplitter, NoHyphenation, WordSplitter};

/// A Wrapper holds settings for wrapping and filling text. Use it
/// when the convenience [`wrap_iter`], [`wrap`] and [`fill`] functions
/// are not flexible enough.
///
/// [`wrap_iter`]: fn.wrap_iter.html
/// [`wrap`]: fn.wrap.html
/// [`fill`]: fn.fill.html
///
/// The algorithm used by the `WrapIter` iterator (returned from the
/// `wrap_iter` method)  works by doing successive partial scans over
/// words in the input string (where each single scan yields a single
/// line) so that the overall time and memory complexity is O(*n*) where
/// *n* is the length of the input string.
#[derive(Clone, Debug)]
pub struct Wrapper<'a, S: WordSplitter> {
    /// The width in columns at which the text will be wrapped.
    pub width: usize,
    /// Indentation used for the first line of output.
    pub initial_indent: &'a str,
    /// Indentation used for subsequent lines of output.
    pub subsequent_indent: &'a str,
    /// Allow long words to be broken if they cannot fit on a line.
    /// When set to `false`, some lines may be longer than
    /// `self.width`.
    pub break_words: bool,
    /// The method for splitting words. If the `hyphenation` feature
    /// is enabled, you can use a `hyphenation::Standard` dictionary
    /// here to get language-aware hyphenation.
    pub splitter: S,
}

impl<'a> Wrapper<'a, HyphenSplitter> {
    /// Create a new Wrapper for wrapping at the specified width. By
    /// default, we allow words longer than `width` to be broken. A
    /// [`HyphenSplitter`] will be used by default for splitting
    /// words. See the [`WordSplitter`] trait for other options.
    ///
    /// [`HyphenSplitter`]: struct.HyphenSplitter.html
    /// [`WordSplitter`]: trait.WordSplitter.html
    pub fn new(width: usize) -> Wrapper<'a, HyphenSplitter> {
        Wrapper::with_splitter(width, HyphenSplitter)
    }

    /// Create a new Wrapper for wrapping text at the current terminal
    /// width. If the terminal width cannot be determined (typically
    /// because the standard input and output is not connected to a
    /// terminal), a width of 80 characters will be used. Other
    /// settings use the same defaults as `Wrapper::new`.
    ///
    /// Equivalent to:
    ///
    /// ```no_run
    /// # #![allow(unused_variables)]
    /// use textwrap::{Wrapper, termwidth};
    ///
    /// let wrapper = Wrapper::new(termwidth());
    /// ```
    #[cfg(feature = "term_size")]
    pub fn with_termwidth() -> Wrapper<'a, HyphenSplitter> {
        Wrapper::new(termwidth())
    }
}

impl<'a, S: WordSplitter> Wrapper<'a, S> {
    /// Use the given [`WordSplitter`] to create a new Wrapper for
    /// wrapping at the specified width. By default, we allow words
    /// longer than `width` to be broken.
    ///
    /// [`WordSplitter`]: trait.WordSplitter.html
    pub fn with_splitter(width: usize, splitter: S) -> Wrapper<'a, S> {
        Wrapper {
            width: width,
            initial_indent: "",
            subsequent_indent: "",
            break_words: true,
            splitter: splitter,
        }
    }

    /// Change [`self.initial_indent`]. The initial indentation is
    /// used on the very first line of output.
    ///
    /// # Examples
    ///
    /// Classic paragraph indentation can be achieved by specifying an
    /// initial indentation and wrapping each paragraph by itself:
    ///
    /// ```no_run
    /// # #![allow(unused_variables)]
    /// use textwrap::Wrapper;
    ///
    /// let wrapper = Wrapper::new(15).initial_indent("    ");
    /// ```
    ///
    /// [`self.initial_indent`]: #structfield.initial_indent
    pub fn initial_indent(self, indent: &'a str) -> Wrapper<'a, S> {
        Wrapper {
            initial_indent: indent,
            ..self
        }
    }

    /// Change [`self.subsequent_indent`]. The subsequent indentation
    /// is used on lines following the first line of output.
    ///
    /// # Examples
    ///
    /// Combining initial and subsequent indentation lets you format a
    /// single paragraph as a bullet list:
    ///
    /// ```no_run
    /// # #![allow(unused_variables)]
    /// use textwrap::Wrapper;
    ///
    /// let wrapper = Wrapper::new(15)
    ///     .initial_indent("* ")
    ///     .subsequent_indent("  ");
    /// ```
    ///
    /// [`self.subsequent_indent`]: #structfield.subsequent_indent
    pub fn subsequent_indent(self, indent: &'a str) -> Wrapper<'a, S> {
        Wrapper {
            subsequent_indent: indent,
            ..self
        }
    }

    /// Change [`self.break_words`]. This controls if words longer
    /// than `self.width` can be broken, or if they will be left
    /// sticking out into the right margin.
    ///
    /// [`self.break_words`]: #structfield.break_words
    pub fn break_words(self, setting: bool) -> Wrapper<'a, S> {
        Wrapper {
            break_words: setting,
            ..self
        }
    }

    /// Fill a line of text at `self.width` characters. Strings are
    /// wrapped based on their displayed width, not their size in
    /// bytes.
    ///
    /// The result is a string with newlines between each line. Use
    /// the `wrap` method if you need access to the individual lines.
    ///
    /// # Complexities
    ///
    /// This method simply joins the lines produced by `wrap_iter`. As
    /// such, it inherits the O(*n*) time and memory complexity where
    /// *n* is the input string length.
    ///
    /// # Examples
    ///
    /// ```
    /// use textwrap::Wrapper;
    ///
    /// let wrapper = Wrapper::new(15);
    /// assert_eq!(wrapper.fill("Memory safety without garbage collection."),
    ///            "Memory safety\nwithout garbage\ncollection.");
    /// ```
    pub fn fill(&self, s: &str) -> String {
        // This will avoid reallocation in simple cases (no
        // indentation, no hyphenation).
        let mut result = String::with_capacity(s.len());

        for (i, line) in self.wrap_iter(s).enumerate() {
            if i > 0 {
                result.push('\n');
            }
            result.push_str(&line);
        }

        result
    }

    /// Wrap a line of text at `self.width` characters. Strings are
    /// wrapped based on their displayed width, not their size in
    /// bytes.
    ///
    /// # Complexities
    ///
    /// This method simply collects the lines produced by `wrap_iter`.
    /// As such, it inherits the O(*n*) overall time and memory
    /// complexity where *n* is the input string length.
    ///
    /// # Examples
    ///
    /// ```
    /// use textwrap::Wrapper;
    ///
    /// let wrap15 = Wrapper::new(15);
    /// assert_eq!(wrap15.wrap("Concurrency without data races."),
    ///            vec!["Concurrency",
    ///                 "without data",
    ///                 "races."]);
    ///
    /// let wrap20 = Wrapper::new(20);
    /// assert_eq!(wrap20.wrap("Concurrency without data races."),
    ///            vec!["Concurrency without",
    ///                 "data races."]);
    /// ```
    ///
    /// Notice that newlines in the input are preserved. This means
    /// that they force a line break, regardless of how long the
    /// current line is:
    ///
    /// ```
    /// use textwrap::Wrapper;
    ///
    /// let wrapper = Wrapper::new(40);
    /// assert_eq!(wrapper.wrap("First line.\nSecond line."),
    ///            vec!["First line.", "Second line."]);
    /// ```
    ///
    pub fn wrap(&self, s: &'a str) -> Vec<Cow<'a, str>> {
        self.wrap_iter(s).collect::<Vec<_>>()
    }

    /// Lazily wrap a line of text at `self.width` characters. Strings
    /// are wrapped based on their displayed width, not their size in
    /// bytes.
    ///
    /// The [`WordSplitter`] stored in [`self.splitter`] is used
    /// whenever when a word is too large to fit on the current line.
    /// By changing the field, different hyphenation strategies can be
    /// implemented.
    ///
    /// # Complexities
    ///
    /// This method returns a [`WrapIter`] iterator which borrows this
    /// `Wrapper`. The algorithm used has a linear complexity, so
    /// getting the next line from the iterator will take O(*w*) time,
    /// where *w* is the wrapping width. Fully processing the iterator
    /// will take O(*n*) time for an input string of length *n*.
    ///
    /// When no indentation is used, each line returned is a slice of
    /// the input string and the memory overhead is thus constant.
    /// Otherwise new memory is allocated for each line returned.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::borrow::Cow;
    /// use textwrap::Wrapper;
    ///
    /// let wrap20 = Wrapper::new(20);
    /// let mut wrap20_iter = wrap20.wrap_iter("Zero-cost abstractions.");
    /// assert_eq!(wrap20_iter.next(), Some(Cow::from("Zero-cost")));
    /// assert_eq!(wrap20_iter.next(), Some(Cow::from("abstractions.")));
    /// assert_eq!(wrap20_iter.next(), None);
    ///
    /// let wrap25 = Wrapper::new(25);
    /// let mut wrap25_iter = wrap25.wrap_iter("Zero-cost abstractions.");
    /// assert_eq!(wrap25_iter.next(), Some(Cow::from("Zero-cost abstractions.")));
    /// assert_eq!(wrap25_iter.next(), None);
    /// ```
    ///
    /// [`self.splitter`]: #structfield.splitter
    /// [`WordSplitter`]: trait.WordSplitter.html
    /// [`WrapIter`]: struct.WrapIter.html
    pub fn wrap_iter<'w>(&'w self, s: &'a str) -> WrapIter<'w, 'a, S> {
        WrapIter {
            wrapper: self,
            inner: WrapIterImpl::new(self, s),
        }
    }

    /// Lazily wrap a line of text at `self.width` characters. Strings
    /// are wrapped based on their displayed width, not their size in
    /// bytes.
    ///
    /// The [`WordSplitter`] stored in [`self.splitter`] is used
    /// whenever when a word is too large to fit on the current line.
    /// By changing the field, different hyphenation strategies can be
    /// implemented.
    ///
    /// # Complexities
    ///
    /// This method consumes the `Wrapper` and returns a
    /// [`IntoWrapIter`] iterator. Fully processing the iterator has
    /// the same O(*n*) time complexity as [`wrap_iter`], where *n* is
    /// the length of the input string.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::borrow::Cow;
    /// use textwrap::Wrapper;
    ///
    /// let wrap20 = Wrapper::new(20);
    /// let mut wrap20_iter = wrap20.into_wrap_iter("Zero-cost abstractions.");
    /// assert_eq!(wrap20_iter.next(), Some(Cow::from("Zero-cost")));
    /// assert_eq!(wrap20_iter.next(), Some(Cow::from("abstractions.")));
    /// assert_eq!(wrap20_iter.next(), None);
    /// ```
    ///
    /// [`self.splitter`]: #structfield.splitter
    /// [`WordSplitter`]: trait.WordSplitter.html
    /// [`IntoWrapIter`]: struct.IntoWrapIter.html
    /// [`wrap_iter`]: #method.wrap_iter
    pub fn into_wrap_iter(self, s: &'a str) -> IntoWrapIter<'a, S> {
        let inner = WrapIterImpl::new(&self, s);

        IntoWrapIter {
            wrapper: self,
            inner: inner,
        }
    }
}

/// An iterator over the lines of the input string which owns a
/// `Wrapper`. An instance of `IntoWrapIter` is typically obtained
/// through either [`wrap_iter`] or [`Wrapper::into_wrap_iter`].
///
/// Each call of `.next()` method yields a line wrapped in `Some` if the
/// input hasn't been fully processed yet. Otherwise it returns `None`.
///
/// [`wrap_iter`]: fn.wrap_iter.html
/// [`Wrapper::into_wrap_iter`]: struct.Wrapper.html#method.into_wrap_iter
#[derive(Debug)]
pub struct IntoWrapIter<'a, S: WordSplitter> {
    wrapper: Wrapper<'a, S>,
    inner: WrapIterImpl<'a>,
}

impl<'a, S: WordSplitter> Iterator for IntoWrapIter<'a, S> {
    type Item = Cow<'a, str>;

    fn next(&mut self) -> Option<Cow<'a, str>> {
        self.inner.next(&self.wrapper)
    }
}

/// An iterator over the lines of the input string which borrows a
/// `Wrapper`. An instance of `WrapIter` is typically obtained
/// through the [`Wrapper::wrap_iter`] method.
///
/// Each call of `.next()` method yields a line wrapped in `Some` if the
/// input hasn't been fully processed yet. Otherwise it returns `None`.
///
/// [`Wrapper::wrap_iter`]: struct.Wrapper.html#method.wrap_iter
#[derive(Debug)]
pub struct WrapIter<'w, 'a: 'w, S: WordSplitter + 'w> {
    wrapper: &'w Wrapper<'a, S>,
    inner: WrapIterImpl<'a>,
}

impl<'w, 'a: 'w, S: WordSplitter> Iterator for WrapIter<'w, 'a, S> {
    type Item = Cow<'a, str>;

    fn next(&mut self) -> Option<Cow<'a, str>> {
        self.inner.next(self.wrapper)
    }
}

/// Like `char::is_whitespace`, but non-breaking spaces don't count.
#[inline]
fn is_whitespace(ch: char) -> bool {
    ch.is_whitespace() && ch != NBSP
}

/// Common implementation details for `WrapIter` and `IntoWrapIter`.
#[derive(Debug)]
struct WrapIterImpl<'a> {
    // String to wrap.
    source: &'a str,
    // CharIndices iterator over self.source.
    char_indices: CharIndices<'a>,
    // Byte index where the current line starts.
    start: usize,
    // Byte index of the last place where the string can be split.
    split: usize,
    // Size in bytes of the character at self.source[self.split].
    split_len: usize,
    // Width of self.source[self.start..idx].
    line_width: usize,
    // Width of self.source[self.start..self.split].
    line_width_at_split: usize,
    // Tracking runs of whitespace characters.
    in_whitespace: bool,
    // Has iterator finished producing elements?
    finished: bool,
}

impl<'a> WrapIterImpl<'a> {
    fn new<S: WordSplitter>(wrapper: &Wrapper<'a, S>, s: &'a str) -> WrapIterImpl<'a> {
        WrapIterImpl {
            source: s,
            char_indices: s.char_indices(),
            start: 0,
            split: 0,
            split_len: 0,
            line_width: wrapper.initial_indent.width(),
            line_width_at_split: wrapper.initial_indent.width(),
            in_whitespace: false,
            finished: false,
        }
    }

    fn create_result_line<S: WordSplitter>(&self, wrapper: &Wrapper<'a, S>) -> Cow<'a, str> {
        if self.start == 0 {
            Cow::from(wrapper.initial_indent)
        } else {
            Cow::from(wrapper.subsequent_indent)
        }
    }

    fn next<S: WordSplitter>(&mut self, wrapper: &Wrapper<'a, S>) -> Option<Cow<'a, str>> {
        if self.finished {
            return None;
        }

        while let Some((idx, ch)) = self.char_indices.next() {
            let char_width = ch.width().unwrap_or(0);
            let char_len = ch.len_utf8();

            if ch == '\n' {
                self.split = idx;
                self.split_len = char_len;
                self.line_width_at_split = self.line_width;
                self.in_whitespace = false;

                // If this is not the final line, return the current line. Otherwise,
                // we will return the line with its line break after exiting the loop
                if self.split + self.split_len < self.source.len() {
                    let mut line = self.create_result_line(wrapper);
                    line += &self.source[self.start..self.split];

                    self.start = self.split + self.split_len;
                    self.line_width = wrapper.subsequent_indent.width();

                    return Some(line);
                }
            } else if is_whitespace(ch) {
                // Extend the previous split or create a new one.
                if self.in_whitespace {
                    self.split_len += char_len;
                } else {
                    self.split = idx;
                    self.split_len = char_len;
                }
                self.line_width_at_split = self.line_width + char_width;
                self.in_whitespace = true;
            } else if self.line_width + char_width > wrapper.width {
                // There is no room for this character on the current
                // line. Try to split the final word.
                self.in_whitespace = false;
                let remaining_text = &self.source[self.split + self.split_len..];
                let final_word = match remaining_text.find(is_whitespace) {
                    Some(i) => &remaining_text[..i],
                    None => remaining_text,
                };

                let mut hyphen = "";
                let splits = wrapper.splitter.split(final_word);
                for &(head, hyp, _) in splits.iter().rev() {
                    if self.line_width_at_split + head.width() + hyp.width() <= wrapper.width {
                        // We can fit head into the current line.
                        // Advance the split point by the width of the
                        // whitespace and the head length.
                        self.split += self.split_len + head.len();
                        self.split_len = 0;
                        hyphen = hyp;
                        break;
                    }
                }

                if self.start >= self.split {
                    // The word is too big to fit on a single line, so we
                    // need to split it at the current index.
                    if wrapper.break_words {
                        // Break work at current index.
                        self.split = idx;
                        self.split_len = 0;
                        self.line_width_at_split = self.line_width;
                    } else {
                        // Add smallest split.
                        self.split = self.start + splits[0].0.len();
                        self.split_len = 0;
                        self.line_width_at_split = self.line_width;
                    }
                }

                if self.start < self.split {
                    let mut line = self.create_result_line(wrapper);
                    line += &self.source[self.start..self.split];
                    line += hyphen;

                    self.start = self.split + self.split_len;
                    self.line_width += wrapper.subsequent_indent.width();
                    self.line_width -= self.line_width_at_split;
                    self.line_width += char_width;

                    return Some(line);
                }
            } else {
                self.in_whitespace = false;
            }
            self.line_width += char_width;
        }

        self.finished = true;

        // Add final line.
        if self.start < self.source.len() {
            let mut line = self.create_result_line(wrapper);
            line += &self.source[self.start..];
            return Some(line);
        }

        None
    }
}

/// Return the current terminal width. If the terminal width cannot be
/// determined (typically because the standard output is not connected
/// to a terminal), a default width of 80 characters will be used.
///
/// # Examples
///
/// Create a `Wrapper` for the current terminal with a two column
/// margin:
///
/// ```no_run
/// # #![allow(unused_variables)]
/// use textwrap::{Wrapper, NoHyphenation, termwidth};
///
/// let width = termwidth() - 4; // Two columns on each side.
/// let wrapper = Wrapper::with_splitter(width, NoHyphenation)
///     .initial_indent("  ")
///     .subsequent_indent("  ");
/// ```
#[cfg(feature = "term_size")]
pub fn termwidth() -> usize {
    term_size::dimensions_stdout().map_or(80, |(w, _)| w)
}

/// Fill a line of text at `width` characters. Strings are wrapped
/// based on their displayed width, not their size in bytes.
///
/// The result is a string with newlines between each line. Use
/// [`wrap`] if you need access to the individual lines or
/// [`wrap_iter`] for its iterator counterpart.
///
/// ```
/// use textwrap::fill;
///
/// assert_eq!(fill("Memory safety without garbage collection.", 15),
///            "Memory safety\nwithout garbage\ncollection.");
/// ```
///
/// This function creates a Wrapper on the fly with default settings.
/// If you need to set a language corpus for automatic hyphenation, or
/// need to fill many strings, then it is suggested to create a Wrapper
/// and call its [`fill` method].
///
/// [`wrap`]: fn.wrap.html
/// [`wrap_iter`]: fn.wrap_iter.html
/// [`fill` method]: struct.Wrapper.html#method.fill
pub fn fill(s: &str, width: usize) -> String {
    Wrapper::new(width).fill(s)
}

/// Wrap a line of text at `width` characters. Strings are wrapped
/// based on their displayed width, not their size in bytes.
///
/// This function creates a Wrapper on the fly with default settings.
/// If you need to set a language corpus for automatic hyphenation, or
/// need to wrap many strings, then it is suggested to create a Wrapper
/// and call its [`wrap` method].
///
/// The result is a vector of strings. Use [`wrap_iter`] if you need an
/// iterator version.
///
/// # Examples
///
/// ```
/// use textwrap::wrap;
///
/// assert_eq!(wrap("Concurrency without data races.", 15),
///            vec!["Concurrency",
///                 "without data",
///                 "races."]);
///
/// assert_eq!(wrap("Concurrency without data races.", 20),
///            vec!["Concurrency without",
///                 "data races."]);
/// ```
///
/// [`wrap_iter`]: fn.wrap_iter.html
/// [`wrap` method]: struct.Wrapper.html#method.wrap
pub fn wrap(s: &str, width: usize) -> Vec<Cow<str>> {
    Wrapper::new(width).wrap(s)
}

/// Lazily wrap a line of text at `width` characters. Strings are
/// wrapped based on their displayed width, not their size in bytes.
///
/// This function creates a Wrapper on the fly with default settings.
/// It then calls the [`into_wrap_iter`] method. Hence, the return
/// value is an [`IntoWrapIter`], not a [`WrapIter`] as the function
/// name would otherwise suggest.
///
/// If you need to set a language corpus for automatic hyphenation, or
/// need to wrap many strings, then it is suggested to create a Wrapper
/// and call its [`wrap_iter`] or [`into_wrap_iter`] methods.
///
/// # Examples
///
/// ```
/// use std::borrow::Cow;
/// use textwrap::wrap_iter;
///
/// let mut wrap20_iter = wrap_iter("Zero-cost abstractions.", 20);
/// assert_eq!(wrap20_iter.next(), Some(Cow::from("Zero-cost")));
/// assert_eq!(wrap20_iter.next(), Some(Cow::from("abstractions.")));
/// assert_eq!(wrap20_iter.next(), None);
///
/// let mut wrap25_iter = wrap_iter("Zero-cost abstractions.", 25);
/// assert_eq!(wrap25_iter.next(), Some(Cow::from("Zero-cost abstractions.")));
/// assert_eq!(wrap25_iter.next(), None);
/// ```
///
/// [`wrap_iter`]: struct.Wrapper.html#method.wrap_iter
/// [`into_wrap_iter`]: struct.Wrapper.html#method.into_wrap_iter
/// [`IntoWrapIter`]: struct.IntoWrapIter.html
/// [`WrapIter`]: struct.WrapIter.html
pub fn wrap_iter(s: &str, width: usize) -> IntoWrapIter<HyphenSplitter> {
    Wrapper::new(width).into_wrap_iter(s)
}

#[cfg(test)]
mod tests {
    #[cfg(feature = "hyphenation")]
    extern crate hyphenation;

    use super::*;
    #[cfg(feature = "hyphenation")]
    use hyphenation::{Language, Load, Standard};

    #[test]
    fn no_wrap() {
        assert_eq!(wrap("foo", 10), vec!["foo"]);
    }

    #[test]
    fn simple() {
        assert_eq!(wrap("foo bar baz", 5), vec!["foo", "bar", "baz"]);
    }

    #[test]
    fn multi_word_on_line() {
        assert_eq!(wrap("foo bar baz", 10), vec!["foo bar", "baz"]);
    }

    #[test]
    fn long_word() {
        assert_eq!(wrap("foo", 0), vec!["f", "o", "o"]);
    }

    #[test]
    fn long_words() {
        assert_eq!(wrap("foo bar", 0), vec!["f", "o", "o", "b", "a", "r"]);
    }

    #[test]
    fn max_width() {
        assert_eq!(wrap("foo bar", usize::max_value()), vec!["foo bar"]);
    }

    #[test]
    fn leading_whitespace() {
        assert_eq!(wrap("  foo bar", 6), vec!["  foo", "bar"]);
    }

    #[test]
    fn trailing_whitespace() {
        assert_eq!(wrap("foo bar  ", 6), vec!["foo", "bar  "]);
    }

    #[test]
    fn interior_whitespace() {
        assert_eq!(wrap("foo:   bar baz", 10), vec!["foo:   bar", "baz"]);
    }

    #[test]
    fn extra_whitespace_start_of_line() {
        // Whitespace is only significant inside a line. After a line
        // gets too long and is broken, the first word starts in
        // column zero and is not indented. The line before might end
        // up with trailing whitespace.
        assert_eq!(wrap("foo               bar", 5), vec!["foo", "bar"]);
    }

    #[test]
    fn issue_99() {
        // We did not reset the in_whitespace flag correctly and did
        // not handle single-character words after a line break.
        assert_eq!(
            wrap("aaabbbccc x yyyzzzwww", 9),
            vec!["aaabbbccc", "x", "yyyzzzwww"]
        );
    }

    #[test]
    fn issue_129() {
        // The dash is an em-dash which takes up four bytes. We used
        // to panic since we tried to index into the character.
        assert_eq!(wrap("x – x", 1), vec!["x", "–", "x"]);
    }

    #[test]
    fn wide_character_handling() {
        assert_eq!(wrap("Hello, World!", 15), vec!["Hello, World!"]);
        assert_eq!(
            wrap("Hello, World!", 15),
            vec!["Hello,", "World!"]
        );
    }

    #[test]
    fn empty_input_not_indented() {
        let wrapper = Wrapper::new(10).initial_indent("!!!");
        assert_eq!(wrapper.fill(""), "");
    }

    #[test]
    fn indent_single_line() {
        let wrapper = Wrapper::new(10).initial_indent(">>>"); // No trailing space
        assert_eq!(wrapper.fill("foo"), ">>>foo");
    }

    #[test]
    fn indent_multiple_lines() {
        let wrapper = Wrapper::new(6).initial_indent("* ").subsequent_indent("  ");
        assert_eq!(wrapper.wrap("foo bar baz"), vec!["* foo", "  bar", "  baz"]);
    }

    #[test]
    fn indent_break_words() {
        let wrapper = Wrapper::new(5).initial_indent("* ").subsequent_indent("  ");
        assert_eq!(wrapper.wrap("foobarbaz"), vec!["* foo", "  bar", "  baz"]);
    }

    #[test]
    fn hyphens() {
        assert_eq!(wrap("foo-bar", 5), vec!["foo-", "bar"]);
    }

    #[test]
    fn trailing_hyphen() {
        let wrapper = Wrapper::new(5).break_words(false);
        assert_eq!(wrapper.wrap("foobar-"), vec!["foobar-"]);
    }

    #[test]
    fn multiple_hyphens() {
        assert_eq!(wrap("foo-bar-baz", 5), vec!["foo-", "bar-", "baz"]);
    }

    #[test]
    fn hyphens_flag() {
        let wrapper = Wrapper::new(5).break_words(false);
        assert_eq!(
            wrapper.wrap("The --foo-bar flag."),
            vec!["The", "--foo-", "bar", "flag."]
        );
    }

    #[test]
    fn repeated_hyphens() {
        let wrapper = Wrapper::new(4).break_words(false);
        assert_eq!(wrapper.wrap("foo--bar"), vec!["foo--bar"]);
    }

    #[test]
    fn hyphens_alphanumeric() {
        assert_eq!(wrap("Na2-CH4", 5), vec!["Na2-", "CH4"]);
    }

    #[test]
    fn hyphens_non_alphanumeric() {
        let wrapper = Wrapper::new(5).break_words(false);
        assert_eq!(wrapper.wrap("foo(-)bar"), vec!["foo(-)bar"]);
    }

    #[test]
    fn multiple_splits() {
        assert_eq!(wrap("foo-bar-baz", 9), vec!["foo-bar-", "baz"]);
    }

    #[test]
    fn forced_split() {
        let wrapper = Wrapper::new(5).break_words(false);
        assert_eq!(wrapper.wrap("foobar-baz"), vec!["foobar-", "baz"]);
    }

    #[test]
    fn no_hyphenation() {
        let wrapper = Wrapper::with_splitter(8, NoHyphenation);
        assert_eq!(wrapper.wrap("foo bar-baz"), vec!["foo", "bar-baz"]);
    }

    #[test]
    #[cfg(feature = "hyphenation")]
    fn auto_hyphenation() {
        let dictionary = Standard::from_embedded(Language::EnglishUS).unwrap();
        let wrapper = Wrapper::new(10);
        assert_eq!(
            wrapper.wrap("Internationalization"),
            vec!["Internatio", "nalization"]
        );

        let wrapper = Wrapper::with_splitter(10, dictionary);
        assert_eq!(
            wrapper.wrap("Internationalization"),
            vec!["Interna-", "tionaliza-", "tion"]
        );
    }

    #[test]
    #[cfg(feature = "hyphenation")]
    fn split_len_hyphenation() {
        // Test that hyphenation takes the width of the wihtespace
        // into account.
        let dictionary = Standard::from_embedded(Language::EnglishUS).unwrap();
        let wrapper = Wrapper::with_splitter(15, dictionary);
        assert_eq!(
            wrapper.wrap("garbage   collection"),
            vec!["garbage   col-", "lection"]
        );
    }

    #[test]
    #[cfg(feature = "hyphenation")]
    fn borrowed_lines() {
        // Lines that end with an extra hyphen are owned, the final
        // line is borrowed.
        use std::borrow::Cow::{Borrowed, Owned};
        let dictionary = Standard::from_embedded(Language::EnglishUS).unwrap();
        let wrapper = Wrapper::with_splitter(10, dictionary);
        let lines = wrapper.wrap("Internationalization");
        if let Borrowed(s) = lines[0] {
            assert!(false, "should not have been borrowed: {:?}", s);
        }
        if let Borrowed(s) = lines[1] {
            assert!(false, "should not have been borrowed: {:?}", s);
        }
        if let Owned(ref s) = lines[2] {
            assert!(false, "should not have been owned: {:?}", s);
        }
    }

    #[test]
    #[cfg(feature = "hyphenation")]
    fn auto_hyphenation_with_hyphen() {
        let dictionary = Standard::from_embedded(Language::EnglishUS).unwrap();
        let wrapper = Wrapper::new(8).break_words(false);
        assert_eq!(wrapper.wrap("over-caffinated"), vec!["over-", "caffinated"]);

        let wrapper = Wrapper::with_splitter(8, dictionary).break_words(false);
        assert_eq!(
            wrapper.wrap("over-caffinated"),
            vec!["over-", "caffi-", "nated"]
        );
    }

    #[test]
    fn break_words() {
        assert_eq!(wrap("foobarbaz", 3), vec!["foo", "bar", "baz"]);
    }

    #[test]
    fn break_words_wide_characters() {
        assert_eq!(wrap("Hello", 5), vec!["He", "ll", "o"]);
    }

    #[test]
    fn break_words_zero_width() {
        assert_eq!(wrap("foobar", 0), vec!["f", "o", "o", "b", "a", "r"]);
    }

    #[test]
    fn break_words_line_breaks() {
        assert_eq!(fill("ab\ncdefghijkl", 5), "ab\ncdefg\nhijkl");
        assert_eq!(fill("abcdefgh\nijkl", 5), "abcde\nfgh\nijkl");
    }

    #[test]
    fn preserve_line_breaks() {
        assert_eq!(fill("test\n", 11), "test\n");
        assert_eq!(fill("test\n\na\n\n", 11), "test\n\na\n\n");
        assert_eq!(fill("1 3 5 7\n1 3 5 7", 7), "1 3 5 7\n1 3 5 7");
    }

    #[test]
    fn wrap_preserve_line_breaks() {
        assert_eq!(fill("1 3 5 7\n1 3 5 7", 5), "1 3 5\n7\n1 3 5\n7");
    }

    #[test]
    fn non_breaking_space() {
        let wrapper = Wrapper::new(5).break_words(false);
        assert_eq!(wrapper.fill("foo bar baz"), "foo bar baz");
    }

    #[test]
    fn non_breaking_hyphen() {
        let wrapper = Wrapper::new(5).break_words(false);
        assert_eq!(wrapper.fill("foo‑bar‑baz"), "foo‑bar‑baz");
    }

    #[test]
    fn fill_simple() {
        assert_eq!(fill("foo bar baz", 10), "foo bar\nbaz");
    }
}