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Diffstat (limited to 'helix-tui/src/widgets/reflow.rs')
| -rw-r--r-- | helix-tui/src/widgets/reflow.rs | 534 |
1 files changed, 534 insertions, 0 deletions
diff --git a/helix-tui/src/widgets/reflow.rs b/helix-tui/src/widgets/reflow.rs new file mode 100644 index 00000000..94ff7330 --- /dev/null +++ b/helix-tui/src/widgets/reflow.rs @@ -0,0 +1,534 @@ +use crate::text::StyledGrapheme; +use unicode_segmentation::UnicodeSegmentation; +use unicode_width::UnicodeWidthStr; + +const NBSP: &str = "\u{00a0}"; + +/// A state machine to pack styled symbols into lines. +/// Cannot implement it as Iterator since it yields slices of the internal buffer (need streaming +/// iterators for that). +pub trait LineComposer<'a> { + fn next_line(&mut self) -> Option<(&[StyledGrapheme<'a>], u16)>; +} + +/// A state machine that wraps lines on word boundaries. +pub struct WordWrapper<'a, 'b> { + symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>, + max_line_width: u16, + current_line: Vec<StyledGrapheme<'a>>, + next_line: Vec<StyledGrapheme<'a>>, + /// Removes the leading whitespace from lines + trim: bool, +} + +impl<'a, 'b> WordWrapper<'a, 'b> { + pub fn new( + symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>, + max_line_width: u16, + trim: bool, + ) -> WordWrapper<'a, 'b> { + WordWrapper { + symbols, + max_line_width, + current_line: vec![], + next_line: vec![], + trim, + } + } +} + +impl<'a, 'b> LineComposer<'a> for WordWrapper<'a, 'b> { + fn next_line(&mut self) -> Option<(&[StyledGrapheme<'a>], u16)> { + if self.max_line_width == 0 { + return None; + } + std::mem::swap(&mut self.current_line, &mut self.next_line); + self.next_line.truncate(0); + + let mut current_line_width = self + .current_line + .iter() + .map(|StyledGrapheme { symbol, .. }| symbol.width() as u16) + .sum(); + + let mut symbols_to_last_word_end: usize = 0; + let mut width_to_last_word_end: u16 = 0; + let mut prev_whitespace = false; + let mut symbols_exhausted = true; + for StyledGrapheme { symbol, style } in &mut self.symbols { + symbols_exhausted = false; + let symbol_whitespace = symbol.chars().all(&char::is_whitespace) && symbol != NBSP; + + // Ignore characters wider that the total max width. + if symbol.width() as u16 > self.max_line_width + // Skip leading whitespace when trim is enabled. + || self.trim && symbol_whitespace && symbol != "\n" && current_line_width == 0 + { + continue; + } + + // Break on newline and discard it. + if symbol == "\n" { + if prev_whitespace { + current_line_width = width_to_last_word_end; + self.current_line.truncate(symbols_to_last_word_end); + } + break; + } + + // Mark the previous symbol as word end. + if symbol_whitespace && !prev_whitespace { + symbols_to_last_word_end = self.current_line.len(); + width_to_last_word_end = current_line_width; + } + + self.current_line.push(StyledGrapheme { symbol, style }); + current_line_width += symbol.width() as u16; + + if current_line_width > self.max_line_width { + // If there was no word break in the text, wrap at the end of the line. + let (truncate_at, truncated_width) = if symbols_to_last_word_end != 0 { + (symbols_to_last_word_end, width_to_last_word_end) + } else { + (self.current_line.len() - 1, self.max_line_width) + }; + + // Push the remainder to the next line but strip leading whitespace: + { + let remainder = &self.current_line[truncate_at..]; + if let Some(remainder_nonwhite) = + remainder.iter().position(|StyledGrapheme { symbol, .. }| { + !symbol.chars().all(&char::is_whitespace) + }) + { + self.next_line + .extend_from_slice(&remainder[remainder_nonwhite..]); + } + } + self.current_line.truncate(truncate_at); + current_line_width = truncated_width; + break; + } + + prev_whitespace = symbol_whitespace; + } + + // Even if the iterator is exhausted, pass the previous remainder. + if symbols_exhausted && self.current_line.is_empty() { + None + } else { + Some((&self.current_line[..], current_line_width)) + } + } +} + +/// A state machine that truncates overhanging lines. +pub struct LineTruncator<'a, 'b> { + symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>, + max_line_width: u16, + current_line: Vec<StyledGrapheme<'a>>, + /// Record the offet to skip render + horizontal_offset: u16, +} + +impl<'a, 'b> LineTruncator<'a, 'b> { + pub fn new( + symbols: &'b mut dyn Iterator<Item = StyledGrapheme<'a>>, + max_line_width: u16, + ) -> LineTruncator<'a, 'b> { + LineTruncator { + symbols, + max_line_width, + horizontal_offset: 0, + current_line: vec![], + } + } + + pub fn set_horizontal_offset(&mut self, horizontal_offset: u16) { + self.horizontal_offset = horizontal_offset; + } +} + +impl<'a, 'b> LineComposer<'a> for LineTruncator<'a, 'b> { + fn next_line(&mut self) -> Option<(&[StyledGrapheme<'a>], u16)> { + if self.max_line_width == 0 { + return None; + } + + self.current_line.truncate(0); + let mut current_line_width = 0; + + let mut skip_rest = false; + let mut symbols_exhausted = true; + let mut horizontal_offset = self.horizontal_offset as usize; + for StyledGrapheme { symbol, style } in &mut self.symbols { + symbols_exhausted = false; + + // Ignore characters wider that the total max width. + if symbol.width() as u16 > self.max_line_width { + continue; + } + + // Break on newline and discard it. + if symbol == "\n" { + break; + } + + if current_line_width + symbol.width() as u16 > self.max_line_width { + // Exhaust the remainder of the line. + skip_rest = true; + break; + } + + let symbol = if horizontal_offset == 0 { + symbol + } else { + let w = symbol.width(); + if w > horizontal_offset { + let t = trim_offset(symbol, horizontal_offset); + horizontal_offset = 0; + t + } else { + horizontal_offset -= w; + "" + } + }; + current_line_width += symbol.width() as u16; + self.current_line.push(StyledGrapheme { symbol, style }); + } + + if skip_rest { + for StyledGrapheme { symbol, .. } in &mut self.symbols { + if symbol == "\n" { + break; + } + } + } + + if symbols_exhausted && self.current_line.is_empty() { + None + } else { + Some((&self.current_line[..], current_line_width)) + } + } +} + +/// This function will return a str slice which start at specified offset. +/// As src is a unicode str, start offset has to be calculated with each character. +fn trim_offset(src: &str, mut offset: usize) -> &str { + let mut start = 0; + for c in UnicodeSegmentation::graphemes(src, true) { + let w = c.width(); + if w <= offset { + offset -= w; + start += c.len(); + } else { + break; + } + } + &src[start..] +} + +#[cfg(test)] +mod test { + use super::*; + use unicode_segmentation::UnicodeSegmentation; + + enum Composer { + WordWrapper { trim: bool }, + LineTruncator, + } + + fn run_composer(which: Composer, text: &str, text_area_width: u16) -> (Vec<String>, Vec<u16>) { + let style = Default::default(); + let mut styled = + UnicodeSegmentation::graphemes(text, true).map(|g| StyledGrapheme { symbol: g, style }); + let mut composer: Box<dyn LineComposer> = match which { + Composer::WordWrapper { trim } => { + Box::new(WordWrapper::new(&mut styled, text_area_width, trim)) + } + Composer::LineTruncator => Box::new(LineTruncator::new(&mut styled, text_area_width)), + }; + let mut lines = vec![]; + let mut widths = vec![]; + while let Some((styled, width)) = composer.next_line() { + let line = styled + .iter() + .map(|StyledGrapheme { symbol, .. }| *symbol) + .collect::<String>(); + assert!(width <= text_area_width); + lines.push(line); + widths.push(width); + } + (lines, widths) + } + + #[test] + fn line_composer_one_line() { + let width = 40; + for i in 1..width { + let text = "a".repeat(i); + let (word_wrapper, _) = + run_composer(Composer::WordWrapper { trim: true }, &text, width as u16); + let (line_truncator, _) = run_composer(Composer::LineTruncator, &text, width as u16); + let expected = vec![text]; + assert_eq!(word_wrapper, expected); + assert_eq!(line_truncator, expected); + } + } + + #[test] + fn line_composer_short_lines() { + let width = 20; + let text = + "abcdefg\nhijklmno\npabcdefg\nhijklmn\nopabcdefghijk\nlmnopabcd\n\n\nefghijklmno"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + + let wrapped: Vec<&str> = text.split('\n').collect(); + assert_eq!(word_wrapper, wrapped); + assert_eq!(line_truncator, wrapped); + } + + #[test] + fn line_composer_long_word() { + let width = 20; + let text = "abcdefghijklmnopabcdefghijklmnopabcdefghijklmnopabcdefghijklmno"; + let (word_wrapper, _) = + run_composer(Composer::WordWrapper { trim: true }, text, width as u16); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width as u16); + + let wrapped = vec![ + &text[..width], + &text[width..width * 2], + &text[width * 2..width * 3], + &text[width * 3..], + ]; + assert_eq!( + word_wrapper, wrapped, + "WordWrapper should detect the line cannot be broken on word boundary and \ + break it at line width limit." + ); + assert_eq!(line_truncator, vec![&text[..width]]); + } + + #[test] + fn line_composer_long_sentence() { + let width = 20; + let text = + "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab c d e f g h i j k l m n o"; + let text_multi_space = + "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab c d e f g h i j k l \ + m n o"; + let (word_wrapper_single_space, _) = + run_composer(Composer::WordWrapper { trim: true }, text, width as u16); + let (word_wrapper_multi_space, _) = run_composer( + Composer::WordWrapper { trim: true }, + text_multi_space, + width as u16, + ); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width as u16); + + let word_wrapped = vec![ + "abcd efghij", + "klmnopabcd efgh", + "ijklmnopabcdefg", + "hijkl mnopab c d e f", + "g h i j k l m n o", + ]; + assert_eq!(word_wrapper_single_space, word_wrapped); + assert_eq!(word_wrapper_multi_space, word_wrapped); + + assert_eq!(line_truncator, vec![&text[..width]]); + } + + #[test] + fn line_composer_zero_width() { + let width = 0; + let text = "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab "; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + + let expected: Vec<&str> = Vec::new(); + assert_eq!(word_wrapper, expected); + assert_eq!(line_truncator, expected); + } + + #[test] + fn line_composer_max_line_width_of_1() { + let width = 1; + let text = "abcd efghij klmnopabcd efgh ijklmnopabcdefg hijkl mnopab "; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + + let expected: Vec<&str> = UnicodeSegmentation::graphemes(text, true) + .filter(|g| g.chars().any(|c| !c.is_whitespace())) + .collect(); + assert_eq!(word_wrapper, expected); + assert_eq!(line_truncator, vec!["a"]); + } + + #[test] + fn line_composer_max_line_width_of_1_double_width_characters() { + let width = 1; + let text = "コンピュータ上で文字を扱う場合、典型的には文字\naaaによる通信を行う場合にその\ + 両端点では、"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + assert_eq!(word_wrapper, vec!["", "a", "a", "a"]); + assert_eq!(line_truncator, vec!["", "a"]); + } + + /// Tests WordWrapper with words some of which exceed line length and some not. + #[test] + fn line_composer_word_wrapper_mixed_length() { + let width = 20; + let text = "abcd efghij klmnopabcdefghijklmnopabcdefghijkl mnopab cdefghi j klmno"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + assert_eq!( + word_wrapper, + vec![ + "abcd efghij", + "klmnopabcdefghijklmn", + "opabcdefghijkl", + "mnopab cdefghi j", + "klmno", + ] + ) + } + + #[test] + fn line_composer_double_width_chars() { + let width = 20; + let text = "コンピュータ上で文字を扱う場合、典型的には文字による通信を行う場合にその両端点\ + では、"; + let (word_wrapper, word_wrapper_width) = + run_composer(Composer::WordWrapper { trim: true }, &text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, &text, width); + assert_eq!(line_truncator, vec!["コンピュータ上で文字"]); + let wrapped = vec![ + "コンピュータ上で文字", + "を扱う場合、典型的に", + "は文字による通信を行", + "う場合にその両端点で", + "は、", + ]; + assert_eq!(word_wrapper, wrapped); + assert_eq!(word_wrapper_width, vec![width, width, width, width, 4]); + } + + #[test] + fn line_composer_leading_whitespace_removal() { + let width = 20; + let text = "AAAAAAAAAAAAAAAAAAAA AAA"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAAAAAAA", "AAA",]); + assert_eq!(line_truncator, vec!["AAAAAAAAAAAAAAAAAAAA"]); + } + + /// Tests truncation of leading whitespace. + #[test] + fn line_composer_lots_of_spaces() { + let width = 20; + let text = " "; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + assert_eq!(word_wrapper, vec![""]); + assert_eq!(line_truncator, vec![" "]); + } + + /// Tests an input starting with a letter, folowed by spaces - some of the behaviour is + /// incidental. + #[test] + fn line_composer_char_plus_lots_of_spaces() { + let width = 20; + let text = "a "; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + let (line_truncator, _) = run_composer(Composer::LineTruncator, text, width); + // What's happening below is: the first line gets consumed, trailing spaces discarded, + // after 20 of which a word break occurs (probably shouldn't). The second line break + // discards all whitespace. The result should probably be vec!["a"] but it doesn't matter + // that much. + assert_eq!(word_wrapper, vec!["a", ""]); + assert_eq!(line_truncator, vec!["a "]); + } + + #[test] + fn line_composer_word_wrapper_double_width_chars_mixed_with_spaces() { + let width = 20; + // Japanese seems not to use spaces but we should break on spaces anyway... We're using it + // to test double-width chars. + // You are more than welcome to add word boundary detection based of alterations of + // hiragana and katakana... + // This happens to also be a test case for mixed width because regular spaces are single width. + let text = "コンピュ ータ上で文字を扱う場合、 典型的には文 字による 通信を行 う場合にその両端点では、"; + let (word_wrapper, word_wrapper_width) = + run_composer(Composer::WordWrapper { trim: true }, text, width); + assert_eq!( + word_wrapper, + vec![ + "コンピュ", + "ータ上で文字を扱う場", + "合、 典型的には文", + "字による 通信を行", + "う場合にその両端点で", + "は、", + ] + ); + // Odd-sized lines have a space in them. + assert_eq!(word_wrapper_width, vec![8, 20, 17, 17, 20, 4]); + } + + /// Ensure words separated by nbsp are wrapped as if they were a single one. + #[test] + fn line_composer_word_wrapper_nbsp() { + let width = 20; + let text = "AAAAAAAAAAAAAAA AAAA\u{00a0}AAA"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: true }, text, width); + assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAA", "AAAA\u{00a0}AAA",]); + + // Ensure that if the character was a regular space, it would be wrapped differently. + let text_space = text.replace("\u{00a0}", " "); + let (word_wrapper_space, _) = + run_composer(Composer::WordWrapper { trim: true }, &text_space, width); + assert_eq!(word_wrapper_space, vec!["AAAAAAAAAAAAAAA AAAA", "AAA",]); + } + + #[test] + fn line_composer_word_wrapper_preserve_indentation() { + let width = 20; + let text = "AAAAAAAAAAAAAAAAAAAA AAA"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: false }, text, width); + assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAAAAAAA", " AAA",]); + } + + #[test] + fn line_composer_word_wrapper_preserve_indentation_with_wrap() { + let width = 10; + let text = "AAA AAA AAAAA AA AAAAAA\n B\n C\n D"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: false }, text, width); + assert_eq!( + word_wrapper, + vec!["AAA AAA", "AAAAA AA", "AAAAAA", " B", " C", " D"] + ); + } + + #[test] + fn line_composer_word_wrapper_preserve_indentation_lots_of_whitespace() { + let width = 10; + let text = " 4 Indent\n must wrap!"; + let (word_wrapper, _) = run_composer(Composer::WordWrapper { trim: false }, text, width); + assert_eq!( + word_wrapper, + vec![ + " ", + " 4", + "Indent", + " ", + " must", + "wrap!" + ] + ); + } +} |