1 // Copyright 2015 The Servo Project Developers. See the
2 // COPYRIGHT file at the top-level directory of this distribution.
3 //
4 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
5 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
7 // option. This file may not be copied, modified, or distributed
8 // except according to those terms.
9 
10 //! This module holds deprecated assets only.
11 
12 // Doesn't worth updating API here
13 #![cfg_attr(feature="cargo-clippy", allow(needless_pass_by_value))]
14 
15 use super::*;
16 
17 /// Find the level runs within a line and return them in visual order.
18 ///
19 /// NOTE: This implementation is incomplete. The algorithm needs information about the text,
20 /// including original `BidiClass` property of each character, to be able to perform correctly.
21 /// Please see [`BidiInfo::visual_runs()`](../struct.BidiInfo.html#method.visual_runs) for the
22 /// improved implementation.
23 ///
24 /// `line` is a range of bytes indices within `levels`.
25 ///
26 /// <http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels>
27 #[deprecated(since = "0.3.0", note = "please use `BidiInfo::visual_runs()` instead.")]
28 pub fn visual_runs(line: Range<usize>, levels: &[Level]) -> Vec<LevelRun> {
29     assert!(line.start <= levels.len());
30     assert!(line.end <= levels.len());
31 
32     let mut runs = Vec::new();
33 
34     // Find consecutive level runs.
35     let mut start = line.start;
36     let mut run_level = levels[start];
37     let mut min_level = run_level;
38     let mut max_level = run_level;
39 
40     for (i, &new_level) in levels.iter().enumerate().take(line.end).skip(start + 1) {
41         if new_level != run_level {
42             // End of the previous run, start of a new one.
43             runs.push(start..i);
44             start = i;
45             run_level = new_level;
46 
47             min_level = min(run_level, min_level);
48             max_level = max(run_level, max_level);
49         }
50     }
51     runs.push(start..line.end);
52 
53     let run_count = runs.len();
54 
55     // Re-order the odd runs.
56     // <http://www.unicode.org/reports/tr9/#L2>
57 
58     // Stop at the lowest *odd* level.
59     min_level = min_level.new_lowest_ge_rtl().expect("Level error");
60 
61     while max_level >= min_level {
62         // Look for the start of a sequence of consecutive runs of max_level or higher.
63         let mut seq_start = 0;
64         while seq_start < run_count {
65             if levels[runs[seq_start].start] < max_level {
66                 seq_start += 1;
67                 continue;
68             }
69 
70             // Found the start of a sequence. Now find the end.
71             let mut seq_end = seq_start + 1;
72             while seq_end < run_count {
73                 if levels[runs[seq_end].start] < max_level {
74                     break;
75                 }
76                 seq_end += 1;
77             }
78 
79             // Reverse the runs within this sequence.
80             runs[seq_start..seq_end].reverse();
81 
82             seq_start = seq_end;
83         }
84         max_level.lower(1).expect(
85             "Lowering embedding level below zero",
86         );
87     }
88 
89     runs
90 }
91