/rust/registry/src/index.crates.io-6f17d22bba15001f/unicode-bidi-0.3.8/src/explicit.rs

Source (jump to first uncovered line)
// Copyright 2015 The Servo Project Developers. See the
// COPYRIGHT file at the top-level directory of this distribution.
//
// 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.

//! 3.3.2 Explicit Levels and Directions
//!
//! <http://www.unicode.org/reports/tr9/#Explicit_Levels_and_Directions>

use alloc::vec::Vec;

use super::char_data::{
    is_rtl,
    BidiClass::{self, *},
};
use super::level::Level;

/// Compute explicit embedding levels for one paragraph of text (X1-X8).
///
/// `processing_classes[i]` must contain the `BidiClass` of the char at byte index `i`,
/// for each char in `text`.
#[cfg_attr(feature = "flame_it", flamer::flame)]
pub fn compute(
    text: &str,
    para_level: Level,
    original_classes: &[BidiClass],
    levels: &mut [Level],
    processing_classes: &mut [BidiClass],
) {
    assert_eq!(text.len(), original_classes.len());

    // <http://www.unicode.org/reports/tr9/#X1>
    let mut stack = DirectionalStatusStack::new();
    stack.push(para_level, OverrideStatus::Neutral);

    let mut overflow_isolate_count = 0u32;
    let mut overflow_embedding_count = 0u32;
    let mut valid_isolate_count = 0u32;

    for (i, c) in text.char_indices() {
        match original_classes[i] {
            // Rules X2-X5c
            RLE | LRE | RLO | LRO | RLI | LRI | FSI => {
                let last_level = stack.last().level;

                // X5a-X5c: Isolate initiators get the level of the last entry on the stack.
                let is_isolate = match original_classes[i] {
                    RLI | LRI | FSI => true,
                    _ => false,
                };
                if is_isolate {
                    levels[i] = last_level;
                    match stack.last().status {
                        OverrideStatus::RTL => processing_classes[i] = R,
                        OverrideStatus::LTR => processing_classes[i] = L,
                        _ => {}
                    }
                }

                let new_level = if is_rtl(original_classes[i]) {
                    last_level.new_explicit_next_rtl()
                } else {
                    last_level.new_explicit_next_ltr()
                };
                if new_level.is_ok() && overflow_isolate_count == 0 && overflow_embedding_count == 0
                {
                    let new_level = new_level.unwrap();
                    stack.push(
                        new_level,
                        match original_classes[i] {
                            RLO => OverrideStatus::RTL,
                            LRO => OverrideStatus::LTR,
                            RLI | LRI | FSI => OverrideStatus::Isolate,
                            _ => OverrideStatus::Neutral,
                        },
                    );
                    if is_isolate {
                        valid_isolate_count += 1;
                    } else {
                        // The spec doesn't explicitly mention this step, but it is necessary.
                        // See the reference implementations for comparison.
                        levels[i] = new_level;
                    }
                } else if is_isolate {
                    overflow_isolate_count += 1;
                } else if overflow_isolate_count == 0 {
                    overflow_embedding_count += 1;
                }
            }

            // <http://www.unicode.org/reports/tr9/#X6a>
            PDI => {
                if overflow_isolate_count > 0 {
                    overflow_isolate_count -= 1;
                } else if valid_isolate_count > 0 {
                    overflow_embedding_count = 0;
                    loop {
                        // Pop everything up to and including the last Isolate status.
                        match stack.vec.pop() {
                            None
                            | Some(Status {
                                status: OverrideStatus::Isolate,
                                ..
                            }) => break,
                            _ => continue,
                        }
                    }
                    valid_isolate_count -= 1;
                }
                let last = stack.last();
                levels[i] = last.level;
                match last.status {
                    OverrideStatus::RTL => processing_classes[i] = R,
                    OverrideStatus::LTR => processing_classes[i] = L,
                    _ => {}
                }
            }

            // <http://www.unicode.org/reports/tr9/#X7>
            PDF => {
                if overflow_isolate_count > 0 {
                    continue;
                }
                if overflow_embedding_count > 0 {
                    overflow_embedding_count -= 1;
                    continue;
                }
                if stack.last().status != OverrideStatus::Isolate && stack.vec.len() >= 2 {
                    stack.vec.pop();
                }
                // The spec doesn't explicitly mention this step, but it is necessary.
                // See the reference implementations for comparison.
                levels[i] = stack.last().level;
            }

            // Nothing
            B | BN => {}

            // <http://www.unicode.org/reports/tr9/#X6>
            _ => {
                let last = stack.last();
                levels[i] = last.level;
                match last.status {
                    OverrideStatus::RTL => processing_classes[i] = R,
                    OverrideStatus::LTR => processing_classes[i] = L,
                    _ => {}
                }
            }
        }

        // Handle multi-byte characters.
        for j in 1..c.len_utf8() {
            levels[i + j] = levels[i];
            processing_classes[i + j] = processing_classes[i];
        }
    }
}

/// Entries in the directional status stack:
struct Status {
    level: Level,
    status: OverrideStatus,
}

#[derive(PartialEq)]
enum OverrideStatus {
    Neutral,
    RTL,
    LTR,
    Isolate,
}

struct DirectionalStatusStack {
    vec: Vec<Status>,
}

impl DirectionalStatusStack {
    fn new() -> Self {
        DirectionalStatusStack {
            vec: Vec::with_capacity(Level::max_explicit_depth() as usize + 2),
        }
    }

    fn push(&mut self, level: Level, status: OverrideStatus) {
        self.vec.push(Status { level, status });
    }

    fn last(&self) -> &Status {
        self.vec.last().unwrap()
    }
}

Line	Count	Source (jump to first uncovered line)
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		//! 3.3.2 Explicit Levels and Directions
11		//!
12		//! <http://www.unicode.org/reports/tr9/#Explicit_Levels_and_Directions>
13
14		use alloc::vec::Vec;
15
16		use super::char_data::{
17		is_rtl,
18		BidiClass::{self, *},
19		};
20		use super::level::Level;
21
22		/// Compute explicit embedding levels for one paragraph of text (X1-X8).
23		///
24		/// `processing_classes[i]` must contain the `BidiClass` of the char at byte index `i`,
25		/// for each char in `text`.
26		#[cfg_attr(feature = "flame_it", flamer::flame)]
27	0	pub fn compute(
28	0	text: &str,
29	0	para_level: Level,
30	0	original_classes: &[BidiClass],
31	0	levels: &mut [Level],
32	0	processing_classes: &mut [BidiClass],
33	0	) {
34	0	assert_eq!(text.len(), original_classes.len());
35
36		// <http://www.unicode.org/reports/tr9/#X1>
37	0	let mut stack = DirectionalStatusStack::new();
38	0	stack.push(para_level, OverrideStatus::Neutral);
39	0
40	0	let mut overflow_isolate_count = 0u32;
41	0	let mut overflow_embedding_count = 0u32;
42	0	let mut valid_isolate_count = 0u32;
43
44	0	for (i, c) in text.char_indices() {
45	0	match original_classes[i] {
46		// Rules X2-X5c
47		RLE \| LRE \| RLO \| LRO \| RLI \| LRI \| FSI => {
48	0	let last_level = stack.last().level;
49
50		// X5a-X5c: Isolate initiators get the level of the last entry on the stack.
51	0	let is_isolate = match original_classes[i] {
52	0	RLI \| LRI \| FSI => true,
53	0	_ => false,
54		};
55	0	if is_isolate {
56	0	levels[i] = last_level;
57	0	match stack.last().status {
58	0	OverrideStatus::RTL => processing_classes[i] = R,
59	0	OverrideStatus::LTR => processing_classes[i] = L,
60	0	_ => {}
61		}
62	0	}
63
64	0	let new_level = if is_rtl(original_classes[i]) {
65	0	last_level.new_explicit_next_rtl()
66		} else {
67	0	last_level.new_explicit_next_ltr()
68		};
69	0	if new_level.is_ok() && overflow_isolate_count == 0 && overflow_embedding_count == 0
70		{
71	0	let new_level = new_level.unwrap();
72	0	stack.push(
73	0	new_level,
74	0	match original_classes[i] {
75	0	RLO => OverrideStatus::RTL,
76	0	LRO => OverrideStatus::LTR,
77	0	RLI \| LRI \| FSI => OverrideStatus::Isolate,
78	0	_ => OverrideStatus::Neutral,
79		},
80		);
81	0	if is_isolate {
82	0	valid_isolate_count += 1;
83	0	} else {
84	0	// The spec doesn't explicitly mention this step, but it is necessary.
85	0	// See the reference implementations for comparison.
86	0	levels[i] = new_level;
87	0	}
88	0	} else if is_isolate {
89	0	overflow_isolate_count += 1;
90	0	} else if overflow_isolate_count == 0 {
91	0	overflow_embedding_count += 1;
92	0	}
93		}
94
95		// <http://www.unicode.org/reports/tr9/#X6a>
96		PDI => {
97	0	if overflow_isolate_count > 0 {
98	0	overflow_isolate_count -= 1;
99	0	} else if valid_isolate_count > 0 {
100	0	overflow_embedding_count = 0;
101		loop {
102		// Pop everything up to and including the last Isolate status.
103	0	match stack.vec.pop() {
104		None
105		\| Some(Status {
106		status: OverrideStatus::Isolate,
107		..
108	0	}) => break,
109	0	_ => continue,
110		}
111		}
112	0	valid_isolate_count -= 1;
113	0	}
114	0	let last = stack.last();
115	0	levels[i] = last.level;
116	0	match last.status {
117	0	OverrideStatus::RTL => processing_classes[i] = R,
118	0	OverrideStatus::LTR => processing_classes[i] = L,
119	0	_ => {}
120		}
121		}
122
123		// <http://www.unicode.org/reports/tr9/#X7>
124		PDF => {
125	0	if overflow_isolate_count > 0 {
126	0	continue;
127	0	}
128	0	if overflow_embedding_count > 0 {
129	0	overflow_embedding_count -= 1;
130	0	continue;
131	0	}
132	0	if stack.last().status != OverrideStatus::Isolate && stack.vec.len() >= 2 {
133	0	stack.vec.pop();
134	0	}
135		// The spec doesn't explicitly mention this step, but it is necessary.
136		// See the reference implementations for comparison.
137	0	levels[i] = stack.last().level;
138		}
139
140		// Nothing
141	0	B \| BN => {}
142
143		// <http://www.unicode.org/reports/tr9/#X6>
144		_ => {
145	0	let last = stack.last();
146	0	levels[i] = last.level;
147	0	match last.status {
148	0	OverrideStatus::RTL => processing_classes[i] = R,
149	0	OverrideStatus::LTR => processing_classes[i] = L,
150	0	_ => {}
151		}
152		}
153		}
154
155		// Handle multi-byte characters.
156	0	for j in 1..c.len_utf8() {
157	0	levels[i + j] = levels[i];
158	0	processing_classes[i + j] = processing_classes[i];
159	0	}
160		}
161	0	}
162
163		/// Entries in the directional status stack:
164		struct Status {
165		level: Level,
166		status: OverrideStatus,
167		}
168
169	0	#[derive(PartialEq)]
170		enum OverrideStatus {
171		Neutral,
172		RTL,
173		LTR,
174		Isolate,
175		}
176
177		struct DirectionalStatusStack {
178		vec: Vec<Status>,
179		}
180
181		impl DirectionalStatusStack {
182	0	fn new() -> Self {
183	0	DirectionalStatusStack {
184	0	vec: Vec::with_capacity(Level::max_explicit_depth() as usize + 2),
185	0	}
186	0	}
187
188	0	fn push(&mut self, level: Level, status: OverrideStatus) {
189	0	self.vec.push(Status { level, status });
190	0	}
191
192	0	fn last(&self) -> &Status {
193	0	self.vec.last().unwrap()
194	0	}
195		}

Coverage Report

Created: 2023-04-25 07:07