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
// 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.
//! 3.3.3 Preparations for Implicit Processing
//!
//! <http://www.unicode.org/reports/tr9/#Preparations_for_Implicit_Processing>
use alloc::vec::Vec;
use core::cmp::max;
use core::ops::Range;
#[cfg(feature = "smallvec")]
use smallvec::{smallvec, SmallVec};
use super::level::Level;
use super::BidiClass::{self, *};
/// A maximal substring of characters with the same embedding level.
///
/// Represented as a range of byte indices.
pub type LevelRun = Range<usize>;
#[cfg(feature = "smallvec")]
pub type LevelRunVec = SmallVec<[LevelRun; 8]>;
#[cfg(not(feature = "smallvec"))]
pub type LevelRunVec = Vec<LevelRun>;
/// Output of `isolating_run_sequences` (steps X9-X10)
#[derive(Debug, PartialEq)]
pub struct IsolatingRunSequence {
pub runs: Vec<LevelRun>,
pub sos: BidiClass, // Start-of-sequence type.
pub eos: BidiClass, // End-of-sequence type.
}
#[cfg(feature = "smallvec")]
pub type IsolatingRunSequenceVec = SmallVec<[IsolatingRunSequence; 8]>;
#[cfg(not(feature = "smallvec"))]
pub type IsolatingRunSequenceVec = Vec<IsolatingRunSequence>;
/// Compute the set of isolating run sequences.
///
/// An isolating run sequence is a maximal sequence of level runs such that for all level runs
/// except the last one in the sequence, the last character of the run is an isolate initiator
/// whose matching PDI is the first character of the next level run in the sequence.
///
/// Note: This function does *not* return the sequences in order by their first characters.
#[cfg_attr(feature = "flame_it", flamer::flame)]
pub fn isolating_run_sequences(
para_level: Level,
original_classes: &[BidiClass],
levels: &[Level],
runs: LevelRunVec,
has_isolate_controls: bool,
isolating_run_sequences: &mut IsolatingRunSequenceVec,
) {
// Per http://www.unicode.org/reports/tr9/#BD13:
// "In the absence of isolate initiators, each isolating run sequence in a paragraph
// consists of exactly one level run, and each level run constitutes a separate
// isolating run sequence."
// We can take a simplified path to handle this case.
if !has_isolate_controls {
isolating_run_sequences.reserve_exact(runs.len());
for run in runs {
// Determine the `sos` and `eos` class for the sequence.
// <http://www.unicode.org/reports/tr9/#X10>
let run_levels = &levels[run.clone()];
let run_classes = &original_classes[run.clone()];
let seq_level = run_levels[run_classes
.iter()
.position(|c| not_removed_by_x9(c))
.unwrap_or(0)];
let end_level = run_levels[run_classes
.iter()
.rposition(|c| not_removed_by_x9(c))
.unwrap_or(run.end - run.start - 1)];
// Get the level of the last non-removed char before the run.
let pred_level = match original_classes[..run.start]
.iter()
.rposition(not_removed_by_x9)
{
Some(idx) => levels[idx],
None => para_level,
};
// Get the level of the next non-removed char after the run.
let succ_level = match original_classes[run.end..]
.iter()
.position(not_removed_by_x9)
{
Some(idx) => levels[run.end + idx],
None => para_level,
};
isolating_run_sequences.push(IsolatingRunSequence {
runs: vec![run],
sos: max(seq_level, pred_level).bidi_class(),
eos: max(end_level, succ_level).bidi_class(),
});
}
return;
}
// Compute the set of isolating run sequences.
// <http://www.unicode.org/reports/tr9/#BD13>
let mut sequences = Vec::with_capacity(runs.len());
// When we encounter an isolate initiator, we push the current sequence onto the
// stack so we can resume it after the matching PDI.
#[cfg(feature = "smallvec")]
let mut stack: SmallVec<[Vec<Range<usize>>; 8]> = smallvec![vec![]];
#[cfg(not(feature = "smallvec"))]
let mut stack = vec![vec![]];
for run in runs {
assert!(!run.is_empty());
assert!(!stack.is_empty());
let start_class = original_classes[run.start];
// > In rule X10, [..] skip over any BNs when [..].
// > Do the same when determining if the last character of the sequence is an isolate initiator.
//
// <https://www.unicode.org/reports/tr9/#Retaining_Explicit_Formatting_Characters>
let end_class = original_classes[run.start..run.end]
.iter()
.copied()
.rev()
.find(not_removed_by_x9)
.unwrap_or(start_class);
let mut sequence = if start_class == PDI && stack.len() > 1 {
// Continue a previous sequence interrupted by an isolate.
stack.pop().unwrap()
} else {
// Start a new sequence.
Vec::new()
};
sequence.push(run);
if matches!(end_class, RLI | LRI | FSI) {
// Resume this sequence after the isolate.
stack.push(sequence);
} else {
// This sequence is finished.
sequences.push(sequence);
}
}
// Pop any remaining sequences off the stack.
sequences.extend(stack.into_iter().rev().filter(|seq| !seq.is_empty()));
// Determine the `sos` and `eos` class for each sequence.
// <http://www.unicode.org/reports/tr9/#X10>
for sequence in sequences {
assert!(!sequence.is_empty());
let start_of_seq = sequence[0].start;
let runs_len = sequence.len();
let end_of_seq = sequence[runs_len - 1].end;
let mut result = IsolatingRunSequence {
runs: sequence,
sos: L,
eos: L,
};
// > (not counting characters removed by X9)
let seq_level = levels[result
.iter_forwards_from(start_of_seq, 0)
.find(|i| not_removed_by_x9(&original_classes[*i]))
.unwrap_or(start_of_seq)];
// XXXManishearth the spec talks of a start and end level,
// but for a given IRS the two should be equivalent, yes?
let end_level = levels[result
.iter_backwards_from(end_of_seq, runs_len - 1)
.find(|i| not_removed_by_x9(&original_classes[*i]))
.unwrap_or(end_of_seq - 1)];
#[cfg(test)]
for idx in result.runs.clone().into_iter().flatten() {
if not_removed_by_x9(&original_classes[idx]) {
assert_eq!(seq_level, levels[idx]);
}
}
// Get the level of the last non-removed char before the runs.
let pred_level = match original_classes[..start_of_seq]
.iter()
.rposition(not_removed_by_x9)
{
Some(idx) => levels[idx],
None => para_level,
};
// Get the last non-removed character to check if it is an isolate initiator.
// The spec calls for an unmatched one, but matched isolate initiators
// will never be at the end of a level run (otherwise there would be more to the run).
// We unwrap_or(BN) because BN marks removed classes and it won't matter for the check.
let last_non_removed = original_classes[..end_of_seq]
.iter()
.copied()
.rev()
.find(not_removed_by_x9)
.unwrap_or(BN);
// Get the level of the next non-removed char after the runs.
let succ_level = if matches!(last_non_removed, RLI | LRI | FSI) {
para_level
} else {
match original_classes[end_of_seq..]
.iter()
.position(not_removed_by_x9)
{
Some(idx) => levels[end_of_seq + idx],
None => para_level,
}
};
result.sos = max(seq_level, pred_level).bidi_class();
result.eos = max(end_level, succ_level).bidi_class();
isolating_run_sequences.push(result);
}
}
impl IsolatingRunSequence {
/// Given a text-relative position `pos` and an index of the level run it is in,
/// produce an iterator of all characters after and pos (`pos..`) that are in this
/// run sequence
pub(crate) fn iter_forwards_from(
&self,
pos: usize,
level_run_index: usize,
) -> impl Iterator<Item = usize> + '_ {
let runs = &self.runs[level_run_index..];
// Check that it is in range
// (we can't use contains() since we want an inclusive range)
#[cfg(feature = "std")]
debug_assert!(runs[0].start <= pos && pos <= runs[0].end);
(pos..runs[0].end).chain(runs[1..].iter().flat_map(Clone::clone))
}
/// Given a text-relative position `pos` and an index of the level run it is in,
/// produce an iterator of all characters before and excludingpos (`..pos`) that are in this
/// run sequence
pub(crate) fn iter_backwards_from(
&self,
pos: usize,
level_run_index: usize,
) -> impl Iterator<Item = usize> + '_ {
let prev_runs = &self.runs[..level_run_index];
let current = &self.runs[level_run_index];
// Check that it is in range
// (we can't use contains() since we want an inclusive range)
#[cfg(feature = "std")]
debug_assert!(current.start <= pos && pos <= current.end);
(current.start..pos)
.rev()
.chain(prev_runs.iter().rev().flat_map(Clone::clone))
}
}
/// Finds the level runs in a paragraph.
///
/// <http://www.unicode.org/reports/tr9/#BD7>
///
/// This is only used by tests; normally level runs are identified during explicit::compute.
#[cfg(test)]
fn level_runs(levels: &[Level], original_classes: &[BidiClass]) -> Vec<LevelRun> {
assert_eq!(levels.len(), original_classes.len());
let mut runs = Vec::new();
if levels.is_empty() {
return runs;
}
let mut current_run_level = levels[0];
let mut current_run_start = 0;
for i in 1..levels.len() {
if !removed_by_x9(original_classes[i]) && levels[i] != current_run_level {
// End the last run and start a new one.
runs.push(current_run_start..i);
current_run_level = levels[i];
current_run_start = i;
}
}
runs.push(current_run_start..levels.len());
runs
}
/// Should this character be ignored in steps after X9?
///
/// <http://www.unicode.org/reports/tr9/#X9>
pub fn removed_by_x9(class: BidiClass) -> bool {
matches!(class, RLE | LRE | RLO | LRO | PDF | BN)
}
// For use as a predicate for `position` / `rposition`
pub fn not_removed_by_x9(class: &BidiClass) -> bool {
!removed_by_x9(*class)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_level_runs() {
assert_eq!(level_runs(&Level::vec(&[]), &[]), &[]);
assert_eq!(
level_runs(&Level::vec(&[0, 0, 0, 1, 1, 2, 0, 0]), &[L; 8]),
&[0..3, 3..5, 5..6, 6..8]
);
}
// From <http://www.unicode.org/reports/tr9/#BD13>
#[rustfmt::skip]
#[test]
fn test_isolating_run_sequences() {
// == Example 1 ==
// text1·RLE·text2·PDF·RLE·text3·PDF·text4
// index 0 1 2 3 4 5 6 7
let classes = &[L, RLE, L, PDF, RLE, L, PDF, L];
let levels = &[0, 1, 1, 1, 1, 1, 1, 0];
let para_level = Level::ltr();
let mut sequences = IsolatingRunSequenceVec::new();
isolating_run_sequences(
para_level,
classes,
&Level::vec(levels),
level_runs(&Level::vec(levels), classes).into(),
false,
&mut sequences);
sequences.sort_by(|a, b| a.runs[0].clone().cmp(b.runs[0].clone()));
assert_eq!(
sequences.iter().map(|s| s.runs.clone()).collect::<Vec<_>>(),
vec![vec![0..2], vec![2..7], vec![7..8]]
);
// == Example 2 ==
// text1·RLI·text2·PDI·RLI·text3·PDI·text4
// index 0 1 2 3 4 5 6 7
let classes = &[L, RLI, L, PDI, RLI, L, PDI, L];
let levels = &[0, 0, 1, 0, 0, 1, 0, 0];
let para_level = Level::ltr();
let mut sequences = IsolatingRunSequenceVec::new();
isolating_run_sequences(
para_level,
classes,
&Level::vec(levels),
level_runs(&Level::vec(levels), classes).into(),
true,
&mut sequences);
sequences.sort_by(|a, b| a.runs[0].clone().cmp(b.runs[0].clone()));
assert_eq!(
sequences.iter().map(|s| s.runs.clone()).collect::<Vec<_>>(),
vec![vec![0..2, 3..5, 6..8], vec![2..3], vec![5..6]]
);
// == Example 3 ==
// text1·RLI·text2·LRI·text3·RLE·text4·PDF·text5·PDI·text6·PDI·text7
// index 0 1 2 3 4 5 6 7 8 9 10 11 12
let classes = &[L, RLI, L, LRI, L, RLE, L, PDF, L, PDI, L, PDI, L];
let levels = &[0, 0, 1, 1, 2, 3, 3, 3, 2, 1, 1, 0, 0];
let para_level = Level::ltr();
let mut sequences = IsolatingRunSequenceVec::new();
isolating_run_sequences(
para_level,
classes,
&Level::vec(levels),
level_runs(&Level::vec(levels), classes).into(),
true,
&mut sequences);
sequences.sort_by(|a, b| a.runs[0].clone().cmp(b.runs[0].clone()));
assert_eq!(
sequences.iter().map(|s| s.runs.clone()).collect::<Vec<_>>(),
vec![vec![0..2, 11..13], vec![2..4, 9..11], vec![4..6], vec![6..8], vec![8..9]]
);
}
// From <http://www.unicode.org/reports/tr9/#X10>
#[rustfmt::skip]
#[test]
fn test_isolating_run_sequences_sos_and_eos() {
// == Example 1 ==
// text1·RLE·text2·LRE·text3·PDF·text4·PDF·RLE·text5·PDF·text6
// index 0 1 2 3 4 5 6 7 8 9 10 11
let classes = &[L, RLE, L, LRE, L, PDF, L, PDF, RLE, L, PDF, L];
let levels = &[0, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 0];
let para_level = Level::ltr();
let mut sequences = IsolatingRunSequenceVec::new();
isolating_run_sequences(
para_level,
classes,
&Level::vec(levels),
level_runs(&Level::vec(levels), classes).into(),
false,
&mut sequences);
sequences.sort_by(|a, b| a.runs[0].clone().cmp(b.runs[0].clone()));
// text1
assert_eq!(
&sequences[0],
&IsolatingRunSequence {
runs: vec![0..2],
sos: L,
eos: R,
}
);
// text2
assert_eq!(
&sequences[1],
&IsolatingRunSequence {
runs: vec![2..4],
sos: R,
eos: L,
}
);
// text3
assert_eq!(
&sequences[2],
&IsolatingRunSequence {
runs: vec![4..6],
sos: L,
eos: L,
}
);
// text4 text5
assert_eq!(
&sequences[3],
&IsolatingRunSequence {
runs: vec![6..11],
sos: L,
eos: R,
}
);
// text6
assert_eq!(
&sequences[4],
&IsolatingRunSequence {
runs: vec![11..12],
sos: R,
eos: L,
}
);
// == Example 2 ==
// text1·RLI·text2·LRI·text3·PDI·text4·PDI·RLI·text5·PDI·text6
// index 0 1 2 3 4 5 6 7 8 9 10 11
let classes = &[L, RLI, L, LRI, L, PDI, L, PDI, RLI, L, PDI, L];
let levels = &[0, 0, 1, 1, 2, 1, 1, 0, 0, 1, 0, 0];
let para_level = Level::ltr();
let mut sequences = IsolatingRunSequenceVec::new();
isolating_run_sequences(
para_level,
classes,
&Level::vec(levels),
level_runs(&Level::vec(levels), classes).into(),
true,
&mut sequences);
sequences.sort_by(|a, b| a.runs[0].clone().cmp(b.runs[0].clone()));
// text1·RLI·PDI·RLI·PDI·text6
assert_eq!(
&sequences[0],
&IsolatingRunSequence {
runs: vec![0..2, 7..9, 10..12],
sos: L,
eos: L,
}
);
// text2·LRI·PDI·text4
assert_eq!(
&sequences[1],
&IsolatingRunSequence {
runs: vec![2..4, 5..7],
sos: R,
eos: R,
}
);
// text3
assert_eq!(
&sequences[2],
&IsolatingRunSequence {
runs: vec![4..5],
sos: L,
eos: L,
}
);
// text5
assert_eq!(
&sequences[3],
&IsolatingRunSequence {
runs: vec![9..10],
sos: R,
eos: R,
}
);
}
#[test]
fn test_removed_by_x9() {
let rem_classes = &[RLE, LRE, RLO, LRO, PDF, BN];
let not_classes = &[L, RLI, AL, LRI, PDI];
for x in rem_classes {
assert_eq!(removed_by_x9(*x), true);
}
for x in not_classes {
assert_eq!(removed_by_x9(*x), false);
}
}
#[test]
fn test_not_removed_by_x9() {
let non_x9_classes = &[L, R, AL, EN, ES, ET, AN, CS, NSM, B, S, WS, ON, LRI, RLI, FSI, PDI];
for x in non_x9_classes {
assert_eq!(not_removed_by_x9(&x), true);
}
}
}