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f1fb451791
This is needed in the future to be able to roll back state within the line breaking when we can't fit even a single word into the line and have to go back to fitting glyph by glyph. For the unicode line break iterator the clone is a little more complicated. The iterator is clone, but the type is anonymous. I first had an implementation to moved the iterator into a closure, which was cloned via another control closure. But that's complicated and still involves allocating the various bits & pieces the closure captures. So instead the simpler solution used here is to allocate the breaks into a shared vector.
42 lines
1.3 KiB
Rust
42 lines
1.3 KiB
Rust
// Copyright © SixtyFPS GmbH <info@slint-ui.com>
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// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-commercial
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#[derive(Copy, Clone, PartialEq, Eq, Debug)]
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pub enum BreakOpportunity {
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Allowed,
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Mandatory,
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}
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#[derive(Clone)]
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pub struct LineBreakIterator<'a> {
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it: core::str::CharIndices<'a>,
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leading_whitespace: bool,
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}
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impl<'a> LineBreakIterator<'a> {
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pub fn new(text: &'a str) -> Self {
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Self { it: text.char_indices(), leading_whitespace: false }
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}
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}
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impl<'a> Iterator for LineBreakIterator<'a> {
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type Item = (usize, BreakOpportunity);
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fn next(&mut self) -> Option<Self::Item> {
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while let Some((byte_offset, char)) = self.it.next() {
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let maybe_opportunity = match char {
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'\u{2028}' | '\u{2029}' => Some(BreakOpportunity::Mandatory), // unicode line- and paragraph separators
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'\n' => Some(BreakOpportunity::Mandatory), // ascii line break
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_ if self.leading_whitespace => Some(BreakOpportunity::Allowed),
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_ => None,
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};
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self.leading_whitespace = char.is_ascii_whitespace();
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if let Some(opportunity) = maybe_opportunity {
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return Some((byte_offset, opportunity));
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}
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}
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None
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}
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}
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