ratatui/src/widgets/reflow.rs
2024-03-03 21:41:20 -08:00

708 lines
28 KiB
Rust

use std::{collections::VecDeque, vec::IntoIter};
use unicode_segmentation::UnicodeSegmentation;
use unicode_width::UnicodeWidthStr;
use crate::{layout::Alignment, text::StyledGrapheme};
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<'lend>(&'lend mut self) -> Option<WrappedLine<'lend, 'a>>;
}
pub struct WrappedLine<'lend, 'text> {
/// One line reflowed to the correct width
pub line: &'lend [StyledGrapheme<'text>],
/// The width of the line
pub width: u16,
/// Whether the line was aligned left or right
pub alignment: Alignment,
}
/// A state machine that wraps lines on word boundaries.
#[derive(Debug, Default, Clone)]
pub struct WordWrapper<'a, O, I>
where
// Outer iterator providing the individual lines
O: Iterator<Item = (I, Alignment)>,
// Inner iterator providing the styled symbols of a line Each line consists of an alignment and
// a series of symbols
I: Iterator<Item = StyledGrapheme<'a>>,
{
/// The given, unprocessed lines
input_lines: O,
max_line_width: u16,
wrapped_lines: Option<IntoIter<Vec<StyledGrapheme<'a>>>>,
current_alignment: Alignment,
current_line: Vec<StyledGrapheme<'a>>,
/// Removes the leading whitespace from lines
trim: bool,
}
impl<'a, O, I> WordWrapper<'a, O, I>
where
O: Iterator<Item = (I, Alignment)>,
I: Iterator<Item = StyledGrapheme<'a>>,
{
pub fn new(lines: O, max_line_width: u16, trim: bool) -> WordWrapper<'a, O, I> {
WordWrapper {
input_lines: lines,
max_line_width,
wrapped_lines: None,
current_alignment: Alignment::Left,
current_line: vec![],
trim,
}
}
}
impl<'a, O, I> LineComposer<'a> for WordWrapper<'a, O, I>
where
O: Iterator<Item = (I, Alignment)>,
I: Iterator<Item = StyledGrapheme<'a>>,
{
fn next_line<'lend>(&'lend mut self) -> Option<WrappedLine<'lend, 'a>> {
if self.max_line_width == 0 {
return None;
}
let mut current_line: Option<Vec<StyledGrapheme<'a>>> = None;
let mut line_width: u16 = 0;
// Try to repeatedly retrieve next line
while current_line.is_none() {
// Retrieve next preprocessed wrapped line
if let Some(line_iterator) = &mut self.wrapped_lines {
if let Some(line) = line_iterator.next() {
line_width = line
.iter()
.map(|grapheme| grapheme.symbol.width())
.sum::<usize>() as u16;
current_line = Some(line);
}
}
// When no more preprocessed wrapped lines
if current_line.is_none() {
// Try to calculate next wrapped lines based on current whole line
if let Some((line_symbols, line_alignment)) = &mut self.input_lines.next() {
// Save the whole line's alignment
self.current_alignment = *line_alignment;
let mut wrapped_lines = vec![]; // Saves the wrapped lines
// Saves the unfinished wrapped line
let (mut current_line, mut current_line_width) = (vec![], 0);
// Saves the partially processed word
let (mut unfinished_word, mut word_width) = (vec![], 0);
// Saves the whitespaces of the partially unfinished word
let (mut unfinished_whitespaces, mut whitespace_width) =
(VecDeque::<StyledGrapheme>::new(), 0);
let mut has_seen_non_whitespace = false;
for StyledGrapheme { symbol, style } in line_symbols {
let symbol_whitespace =
symbol.chars().all(&char::is_whitespace) && symbol != NBSP;
let symbol_width = symbol.width() as u16;
// Ignore characters wider than the total max width
if symbol_width > self.max_line_width {
continue;
}
// Append finished word to current line
if has_seen_non_whitespace && symbol_whitespace
// Append if trimmed (whitespaces removed) word would overflow
|| word_width + symbol_width > self.max_line_width && current_line.is_empty() && self.trim
// Append if removed whitespace would overflow -> reset whitespace counting to prevent overflow
|| whitespace_width + symbol_width > self.max_line_width && current_line.is_empty() && self.trim
// Append if complete word would overflow
|| word_width + whitespace_width + symbol_width > self.max_line_width && current_line.is_empty() && !self.trim
{
if !current_line.is_empty() || !self.trim {
// Also append whitespaces if not trimming or current line is not
// empty
current_line.extend(
std::mem::take(&mut unfinished_whitespaces).into_iter(),
);
current_line_width += whitespace_width;
}
// Append trimmed word
current_line.append(&mut unfinished_word);
current_line_width += word_width;
// Clear whitespace buffer
unfinished_whitespaces.clear();
whitespace_width = 0;
word_width = 0;
}
// Append the unfinished wrapped line to wrapped lines if it is as wide as
// max line width
if current_line_width >= self.max_line_width
// or if it would be too long with the current partially processed word added
|| current_line_width + whitespace_width + word_width >= self.max_line_width && symbol_width > 0
{
let mut remaining_width =
(self.max_line_width as i32 - current_line_width as i32).max(0)
as u16;
wrapped_lines.push(std::mem::take(&mut current_line));
current_line_width = 0;
// Remove all whitespaces till end of just appended wrapped line + next
// whitespace
let mut first_whitespace = unfinished_whitespaces.pop_front();
while let Some(grapheme) = first_whitespace.as_ref() {
let symbol_width = grapheme.symbol.width() as u16;
whitespace_width -= symbol_width;
if symbol_width > remaining_width {
break;
}
remaining_width -= symbol_width;
first_whitespace = unfinished_whitespaces.pop_front();
}
// In case all whitespaces have been exhausted
if symbol_whitespace && first_whitespace.is_none() {
// Prevent first whitespace to count towards next word
continue;
}
}
// Append symbol to unfinished, partially processed word
if symbol_whitespace {
whitespace_width += symbol_width;
unfinished_whitespaces.push_back(StyledGrapheme { symbol, style });
} else {
word_width += symbol_width;
unfinished_word.push(StyledGrapheme { symbol, style });
}
has_seen_non_whitespace = !symbol_whitespace;
}
// Append remaining text parts
if !unfinished_word.is_empty() || !unfinished_whitespaces.is_empty() {
if current_line.is_empty() && unfinished_word.is_empty() {
wrapped_lines.push(vec![]);
} else if !self.trim || !current_line.is_empty() {
current_line.extend(unfinished_whitespaces.into_iter());
}
current_line.append(&mut unfinished_word);
}
if !current_line.is_empty() {
wrapped_lines.push(current_line);
}
if wrapped_lines.is_empty() {
// Append empty line if there was nothing to wrap in the first place
wrapped_lines.push(vec![]);
}
self.wrapped_lines = Some(wrapped_lines.into_iter());
} else {
// No more whole lines available -> stop repeatedly retrieving next wrapped line
break;
}
}
}
if let Some(line) = current_line {
self.current_line = line;
Some(WrappedLine {
line: &self.current_line,
width: line_width,
alignment: self.current_alignment,
})
} else {
None
}
}
}
/// A state machine that truncates overhanging lines.
#[derive(Debug, Default, Clone)]
pub struct LineTruncator<'a, O, I>
where
// Outer iterator providing the individual lines
O: Iterator<Item = (I, Alignment)>,
// Inner iterator providing the styled symbols of a line Each line consists of an alignment and
// a series of symbols
I: Iterator<Item = StyledGrapheme<'a>>,
{
/// The given, unprocessed lines
input_lines: O,
max_line_width: u16,
current_line: Vec<StyledGrapheme<'a>>,
/// Record the offset to skip render
horizontal_offset: u16,
}
impl<'a, O, I> LineTruncator<'a, O, I>
where
O: Iterator<Item = (I, Alignment)>,
I: Iterator<Item = StyledGrapheme<'a>>,
{
pub fn new(lines: O, max_line_width: u16) -> LineTruncator<'a, O, I> {
LineTruncator {
input_lines: lines,
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, O, I> LineComposer<'a> for LineTruncator<'a, O, I>
where
O: Iterator<Item = (I, Alignment)>,
I: Iterator<Item = StyledGrapheme<'a>>,
{
fn next_line<'lend>(&'lend mut self) -> Option<WrappedLine<'lend, 'a>> {
if self.max_line_width == 0 {
return None;
}
self.current_line.truncate(0);
let mut current_line_width = 0;
let mut lines_exhausted = true;
let mut horizontal_offset = self.horizontal_offset as usize;
let mut current_alignment = Alignment::Left;
if let Some((current_line, alignment)) = &mut self.input_lines.next() {
lines_exhausted = false;
current_alignment = *alignment;
for StyledGrapheme { symbol, style } in current_line {
// Ignore characters wider that the total max width.
if symbol.width() as u16 > self.max_line_width {
continue;
}
if current_line_width + symbol.width() as u16 > self.max_line_width {
// Truncate line
break;
}
let symbol = if horizontal_offset == 0 || Alignment::Left != *alignment {
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 lines_exhausted {
None
} else {
Some(WrappedLine {
line: &self.current_line,
width: current_line_width,
alignment: current_alignment,
})
}
}
}
/// 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 unicode_segmentation::UnicodeSegmentation;
use super::*;
use crate::{
style::Style,
text::{Line, Text},
};
#[derive(Clone, Copy)]
enum Composer {
WordWrapper { trim: bool },
LineTruncator,
}
fn run_composer<'a>(
which: Composer,
text: impl Into<Text<'a>>,
text_area_width: u16,
) -> (Vec<String>, Vec<u16>, Vec<Alignment>) {
let text = text.into();
let styled_lines = text.iter().map(|line| {
(
line.iter()
.flat_map(|span| span.styled_graphemes(Style::default())),
line.alignment.unwrap_or(Alignment::Left),
)
});
let mut composer: Box<dyn LineComposer> = match which {
Composer::WordWrapper { trim } => {
Box::new(WordWrapper::new(styled_lines, text_area_width, trim))
}
Composer::LineTruncator => Box::new(LineTruncator::new(styled_lines, text_area_width)),
};
let mut lines = vec![];
let mut widths = vec![];
let mut alignments = vec![];
while let Some(WrappedLine {
line: styled,
width,
alignment,
}) = composer.next_line()
{
let line = styled
.iter()
.map(|StyledGrapheme { symbol, .. }| *symbol)
.collect::<String>();
assert!(width <= text_area_width);
lines.push(line);
widths.push(width);
alignments.push(alignment);
}
(lines, widths, alignments)
}
#[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\na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", "a"]);
assert_eq!(line_truncator, vec!["", "a", "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, followed 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, word_wrapper_widths, _) =
run_composer(Composer::WordWrapper { trim: true }, text, width);
assert_eq!(word_wrapper, vec!["AAAAAAAAAAAAAAA", "AAAA\u{00a0}AAA",]);
assert_eq!(word_wrapper_widths, vec![15, 8]);
// 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, word_wrapper_widths, _) =
run_composer(Composer::WordWrapper { trim: true }, text_space, width);
assert_eq!(word_wrapper_space, vec!["AAAAAAAAAAAAAAA AAAA", "AAA",]);
assert_eq!(word_wrapper_widths, vec![20, 3]);
}
#[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!"
]
);
}
#[test]
fn line_composer_zero_width_at_end() {
let width = 3;
let line = "foo\0";
let (word_wrapper, _, _) = run_composer(Composer::WordWrapper { trim: true }, line, width);
let (line_truncator, _, _) = run_composer(Composer::LineTruncator, line, width);
assert_eq!(word_wrapper, vec!["foo\0"]);
assert_eq!(line_truncator, vec!["foo\0"]);
}
#[test]
fn line_composer_preserves_line_alignment() {
let width = 20;
let lines = vec![
Line::from("Something that is left aligned.").alignment(Alignment::Left),
Line::from("This is right aligned and half short.").alignment(Alignment::Right),
Line::from("This should sit in the center.").alignment(Alignment::Center),
];
let (_, _, wrapped_alignments) =
run_composer(Composer::WordWrapper { trim: true }, lines.clone(), width);
let (_, _, truncated_alignments) = run_composer(Composer::LineTruncator, lines, width);
assert_eq!(
wrapped_alignments,
vec![
Alignment::Left,
Alignment::Left,
Alignment::Right,
Alignment::Right,
Alignment::Right,
Alignment::Center,
Alignment::Center
]
);
assert_eq!(
truncated_alignments,
vec![Alignment::Left, Alignment::Right, Alignment::Center]
);
}
}