unicode_bidi/
deprecated.rs

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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
12use super::*;
13
14/// Find the level runs within a line and return them in visual order.
15///
16/// NOTE: This implementation is incomplete. The algorithm needs information about the text,
17/// including original `BidiClass` property of each character, to be able to perform correctly.
18/// Please see [`BidiInfo::visual_runs()`](../struct.BidiInfo.html#method.visual_runs) for the
19/// improved implementation.
20///
21/// `line` is a range of bytes indices within `levels`.
22///
23/// <http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels>
24#[deprecated(
25    since = "0.3.0",
26    note = "please use `BidiInfo::visual_runs()` instead."
27)]
28pub 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 = cmp::min(run_level, min_level);
48            max_level = cmp::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
73            while seq_end < run_count && levels[runs[seq_end].start] >= max_level {
74                seq_end += 1;
75            }
76
77            // Reverse the runs within this sequence.
78            runs[seq_start..seq_end].reverse();
79
80            seq_start = seq_end;
81        }
82
83        max_level
84            .lower(1)
85            .expect("Lowering embedding level below zero");
86    }
87
88    runs
89}
unicode_bidi/deprecated.rs

unicode_bidi/
deprecated.rs
