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authorValentin Popov <valentin@popov.link>2024-01-08 00:21:28 +0300
committerValentin Popov <valentin@popov.link>2024-01-08 00:21:28 +0300
commit1b6a04ca5504955c571d1c97504fb45ea0befee4 (patch)
tree7579f518b23313e8a9748a88ab6173d5e030b227 /vendor/textwrap/src/core.rs
parent5ecd8cf2cba827454317368b68571df0d13d7842 (diff)
downloadfparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.tar.xz
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Initial vendor packages
Signed-off-by: Valentin Popov <valentin@popov.link>
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+//! Building blocks for advanced wrapping functionality.
+//!
+//! The functions and structs in this module can be used to implement
+//! advanced wrapping functionality when the [`wrap`](super::wrap) and
+//! [`fill`](super::fill) function don't do what you want.
+//!
+//! In general, you want to follow these steps when wrapping
+//! something:
+//!
+//! 1. Split your input into [`Fragment`]s. These are abstract blocks
+//! of text or content which can be wrapped into lines. See
+//! [`WordSeparator`](crate::word_separators::WordSeparator) for
+//! how to do this for text.
+//!
+//! 2. Potentially split your fragments into smaller pieces. This
+//! allows you to implement things like hyphenation. If you use the
+//! `Word` type, you can use [`WordSplitter`](crate::WordSplitter)
+//! enum for this.
+//!
+//! 3. Potentially break apart fragments that are still too large to
+//! fit on a single line. This is implemented in [`break_words`].
+//!
+//! 4. Finally take your fragments and put them into lines. There are
+//! two algorithms for this in the
+//! [`wrap_algorithms`](crate::wrap_algorithms) module:
+//! [`wrap_optimal_fit`](crate::wrap_algorithms::wrap_optimal_fit)
+//! and [`wrap_first_fit`](crate::wrap_algorithms::wrap_first_fit).
+//! The former produces better line breaks, the latter is faster.
+//!
+//! 5. Iterate through the slices returned by the wrapping functions
+//! and construct your lines of output.
+//!
+//! Please [open an issue](https://github.com/mgeisler/textwrap/) if
+//! the functionality here is not sufficient or if you have ideas for
+//! improving it. We would love to hear from you!
+
+/// The CSI or “Control Sequence Introducer” introduces an ANSI escape
+/// sequence. This is typically used for colored text and will be
+/// ignored when computing the text width.
+const CSI: (char, char) = ('\x1b', '[');
+/// The final bytes of an ANSI escape sequence must be in this range.
+const ANSI_FINAL_BYTE: std::ops::RangeInclusive<char> = '\x40'..='\x7e';
+
+/// Skip ANSI escape sequences. The `ch` is the current `char`, the
+/// `chars` provide the following characters. The `chars` will be
+/// modified if `ch` is the start of an ANSI escape sequence.
+#[inline]
+pub(crate) fn skip_ansi_escape_sequence<I: Iterator<Item = char>>(ch: char, chars: &mut I) -> bool {
+ if ch == CSI.0 && chars.next() == Some(CSI.1) {
+ // We have found the start of an ANSI escape code, typically
+ // used for colored terminal text. We skip until we find a
+ // "final byte" in the range 0x40–0x7E.
+ for ch in chars {
+ if ANSI_FINAL_BYTE.contains(&ch) {
+ return true;
+ }
+ }
+ }
+ false
+}
+
+#[cfg(feature = "unicode-width")]
+#[inline]
+fn ch_width(ch: char) -> usize {
+ unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0)
+}
+
+/// First character which [`ch_width`] will classify as double-width.
+/// Please see [`display_width`].
+#[cfg(not(feature = "unicode-width"))]
+const DOUBLE_WIDTH_CUTOFF: char = '\u{1100}';
+
+#[cfg(not(feature = "unicode-width"))]
+#[inline]
+fn ch_width(ch: char) -> usize {
+ if ch < DOUBLE_WIDTH_CUTOFF {
+ 1
+ } else {
+ 2
+ }
+}
+
+/// Compute the display width of `text` while skipping over ANSI
+/// escape sequences.
+///
+/// # Examples
+///
+/// ```
+/// use textwrap::core::display_width;
+///
+/// assert_eq!(display_width("Café Plain"), 10);
+/// assert_eq!(display_width("\u{1b}[31mCafé Rouge\u{1b}[0m"), 10);
+/// ```
+///
+/// **Note:** When the `unicode-width` Cargo feature is disabled, the
+/// width of a `char` is determined by a crude approximation which
+/// simply counts chars below U+1100 as 1 column wide, and all other
+/// characters as 2 columns wide. With the feature enabled, function
+/// will correctly deal with [combining characters] in their
+/// decomposed form (see [Unicode equivalence]).
+///
+/// An example of a decomposed character is “é”, which can be
+/// decomposed into: “e” followed by a combining acute accent: “◌́”.
+/// Without the `unicode-width` Cargo feature, every `char` below
+/// U+1100 has a width of 1. This includes the combining accent:
+///
+/// ```
+/// use textwrap::core::display_width;
+///
+/// assert_eq!(display_width("Cafe Plain"), 10);
+/// #[cfg(feature = "unicode-width")]
+/// assert_eq!(display_width("Cafe\u{301} Plain"), 10);
+/// #[cfg(not(feature = "unicode-width"))]
+/// assert_eq!(display_width("Cafe\u{301} Plain"), 11);
+/// ```
+///
+/// ## Emojis and CJK Characters
+///
+/// Characters such as emojis and [CJK characters] used in the
+/// Chinese, Japanese, and Korean langauges are seen as double-width,
+/// even if the `unicode-width` feature is disabled:
+///
+/// ```
+/// use textwrap::core::display_width;
+///
+/// assert_eq!(display_width("😂😭🥺🤣✨😍🙏🥰😊🔥"), 20);
+/// assert_eq!(display_width("你好"), 4); // “Nǐ hǎo” or “Hello” in Chinese
+/// ```
+///
+/// # Limitations
+///
+/// The displayed width of a string cannot always be computed from the
+/// string alone. This is because the width depends on the rendering
+/// engine used. This is particularly visible with [emoji modifier
+/// sequences] where a base emoji is modified with, e.g., skin tone or
+/// hair color modifiers. It is up to the rendering engine to detect
+/// this and to produce a suitable emoji.
+///
+/// A simple example is “❤️”, which consists of “❤” (U+2764: Black
+/// Heart Symbol) followed by U+FE0F (Variation Selector-16). By
+/// itself, “❤” is a black heart, but if you follow it with the
+/// variant selector, you may get a wider red heart.
+///
+/// A more complex example would be “👨‍🦰” which should depict a man
+/// with red hair. Here the computed width is too large — and the
+/// width differs depending on the use of the `unicode-width` feature:
+///
+/// ```
+/// use textwrap::core::display_width;
+///
+/// assert_eq!("👨‍🦰".chars().collect::<Vec<char>>(), ['\u{1f468}', '\u{200d}', '\u{1f9b0}']);
+/// #[cfg(feature = "unicode-width")]
+/// assert_eq!(display_width("👨‍🦰"), 4);
+/// #[cfg(not(feature = "unicode-width"))]
+/// assert_eq!(display_width("👨‍🦰"), 6);
+/// ```
+///
+/// This happens because the grapheme consists of three code points:
+/// “👨” (U+1F468: Man), Zero Width Joiner (U+200D), and “🦰”
+/// (U+1F9B0: Red Hair). You can see them above in the test. With
+/// `unicode-width` enabled, the ZWJ is correctly seen as having zero
+/// width, without it is counted as a double-width character.
+///
+/// ## Terminal Support
+///
+/// Modern browsers typically do a great job at combining characters
+/// as shown above, but terminals often struggle more. As an example,
+/// Gnome Terminal version 3.38.1, shows “❤️” as a big red heart, but
+/// shows "👨‍🦰" as “👨🦰”.
+///
+/// [combining characters]: https://en.wikipedia.org/wiki/Combining_character
+/// [Unicode equivalence]: https://en.wikipedia.org/wiki/Unicode_equivalence
+/// [CJK characters]: https://en.wikipedia.org/wiki/CJK_characters
+/// [emoji modifier sequences]: https://unicode.org/emoji/charts/full-emoji-modifiers.html
+pub fn display_width(text: &str) -> usize {
+ let mut chars = text.chars();
+ let mut width = 0;
+ while let Some(ch) = chars.next() {
+ if skip_ansi_escape_sequence(ch, &mut chars) {
+ continue;
+ }
+ width += ch_width(ch);
+ }
+ width
+}
+
+/// A (text) fragment denotes the unit which we wrap into lines.
+///
+/// Fragments represent an abstract _word_ plus the _whitespace_
+/// following the word. In case the word falls at the end of the line,
+/// the whitespace is dropped and a so-called _penalty_ is inserted
+/// instead (typically `"-"` if the word was hyphenated).
+///
+/// For wrapping purposes, the precise content of the word, the
+/// whitespace, and the penalty is irrelevant. All we need to know is
+/// the displayed width of each part, which this trait provides.
+pub trait Fragment: std::fmt::Debug {
+ /// Displayed width of word represented by this fragment.
+ fn width(&self) -> f64;
+
+ /// Displayed width of the whitespace that must follow the word
+ /// when the word is not at the end of a line.
+ fn whitespace_width(&self) -> f64;
+
+ /// Displayed width of the penalty that must be inserted if the
+ /// word falls at the end of a line.
+ fn penalty_width(&self) -> f64;
+}
+
+/// A piece of wrappable text, including any trailing whitespace.
+///
+/// A `Word` is an example of a [`Fragment`], so it has a width,
+/// trailing whitespace, and potentially a penalty item.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct Word<'a> {
+ /// Word content.
+ pub word: &'a str,
+ /// Whitespace to insert if the word does not fall at the end of a line.
+ pub whitespace: &'a str,
+ /// Penalty string to insert if the word falls at the end of a line.
+ pub penalty: &'a str,
+ // Cached width in columns.
+ pub(crate) width: usize,
+}
+
+impl std::ops::Deref for Word<'_> {
+ type Target = str;
+
+ fn deref(&self) -> &Self::Target {
+ self.word
+ }
+}
+
+impl<'a> Word<'a> {
+ /// Construct a `Word` from a string.
+ ///
+ /// A trailing stretch of `' '` is automatically taken to be the
+ /// whitespace part of the word.
+ pub fn from(word: &str) -> Word<'_> {
+ let trimmed = word.trim_end_matches(' ');
+ Word {
+ word: trimmed,
+ width: display_width(trimmed),
+ whitespace: &word[trimmed.len()..],
+ penalty: "",
+ }
+ }
+
+ /// Break this word into smaller words with a width of at most
+ /// `line_width`. The whitespace and penalty from this `Word` is
+ /// added to the last piece.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use textwrap::core::Word;
+ /// assert_eq!(
+ /// Word::from("Hello! ").break_apart(3).collect::<Vec<_>>(),
+ /// vec![Word::from("Hel"), Word::from("lo! ")]
+ /// );
+ /// ```
+ pub fn break_apart<'b>(&'b self, line_width: usize) -> impl Iterator<Item = Word<'a>> + 'b {
+ let mut char_indices = self.word.char_indices();
+ let mut offset = 0;
+ let mut width = 0;
+
+ std::iter::from_fn(move || {
+ while let Some((idx, ch)) = char_indices.next() {
+ if skip_ansi_escape_sequence(ch, &mut char_indices.by_ref().map(|(_, ch)| ch)) {
+ continue;
+ }
+
+ if width > 0 && width + ch_width(ch) > line_width {
+ let word = Word {
+ word: &self.word[offset..idx],
+ width: width,
+ whitespace: "",
+ penalty: "",
+ };
+ offset = idx;
+ width = ch_width(ch);
+ return Some(word);
+ }
+
+ width += ch_width(ch);
+ }
+
+ if offset < self.word.len() {
+ let word = Word {
+ word: &self.word[offset..],
+ width: width,
+ whitespace: self.whitespace,
+ penalty: self.penalty,
+ };
+ offset = self.word.len();
+ return Some(word);
+ }
+
+ None
+ })
+ }
+}
+
+impl Fragment for Word<'_> {
+ #[inline]
+ fn width(&self) -> f64 {
+ self.width as f64
+ }
+
+ // We assume the whitespace consist of ' ' only. This allows us to
+ // compute the display width in constant time.
+ #[inline]
+ fn whitespace_width(&self) -> f64 {
+ self.whitespace.len() as f64
+ }
+
+ // We assume the penalty is `""` or `"-"`. This allows us to
+ // compute the display width in constant time.
+ #[inline]
+ fn penalty_width(&self) -> f64 {
+ self.penalty.len() as f64
+ }
+}
+
+/// Forcibly break words wider than `line_width` into smaller words.
+///
+/// This simply calls [`Word::break_apart`] on words that are too
+/// wide. This means that no extra `'-'` is inserted, the word is
+/// simply broken into smaller pieces.
+pub fn break_words<'a, I>(words: I, line_width: usize) -> Vec<Word<'a>>
+where
+ I: IntoIterator<Item = Word<'a>>,
+{
+ let mut shortened_words = Vec::new();
+ for word in words {
+ if word.width() > line_width as f64 {
+ shortened_words.extend(word.break_apart(line_width));
+ } else {
+ shortened_words.push(word);
+ }
+ }
+ shortened_words
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[cfg(feature = "unicode-width")]
+ use unicode_width::UnicodeWidthChar;
+
+ #[test]
+ fn skip_ansi_escape_sequence_works() {
+ let blue_text = "\u{1b}[34mHello\u{1b}[0m";
+ let mut chars = blue_text.chars();
+ let ch = chars.next().unwrap();
+ assert!(skip_ansi_escape_sequence(ch, &mut chars));
+ assert_eq!(chars.next(), Some('H'));
+ }
+
+ #[test]
+ fn emojis_have_correct_width() {
+ use unic_emoji_char::is_emoji;
+
+ // Emojis in the Basic Latin (ASCII) and Latin-1 Supplement
+ // blocks all have a width of 1 column. This includes
+ // characters such as '#' and '©'.
+ for ch in '\u{1}'..'\u{FF}' {
+ if is_emoji(ch) {
+ let desc = format!("{:?} U+{:04X}", ch, ch as u32);
+
+ #[cfg(feature = "unicode-width")]
+ assert_eq!(ch.width().unwrap(), 1, "char: {}", desc);
+
+ #[cfg(not(feature = "unicode-width"))]
+ assert_eq!(ch_width(ch), 1, "char: {}", desc);
+ }
+ }
+
+ // Emojis in the remaining blocks of the Basic Multilingual
+ // Plane (BMP), in the Supplementary Multilingual Plane (SMP),
+ // and in the Supplementary Ideographic Plane (SIP), are all 1
+ // or 2 columns wide when unicode-width is used, and always 2
+ // columns wide otherwise. This includes all of our favorite
+ // emojis such as 😊.
+ for ch in '\u{FF}'..'\u{2FFFF}' {
+ if is_emoji(ch) {
+ let desc = format!("{:?} U+{:04X}", ch, ch as u32);
+
+ #[cfg(feature = "unicode-width")]
+ assert!(ch.width().unwrap() <= 2, "char: {}", desc);
+
+ #[cfg(not(feature = "unicode-width"))]
+ assert_eq!(ch_width(ch), 2, "char: {}", desc);
+ }
+ }
+
+ // The remaining planes contain almost no assigned code points
+ // and thus also no emojis.
+ }
+
+ #[test]
+ fn display_width_works() {
+ assert_eq!("Café Plain".len(), 11); // “é” is two bytes
+ assert_eq!(display_width("Café Plain"), 10);
+ assert_eq!(display_width("\u{1b}[31mCafé Rouge\u{1b}[0m"), 10);
+ }
+
+ #[test]
+ fn display_width_narrow_emojis() {
+ #[cfg(feature = "unicode-width")]
+ assert_eq!(display_width("⁉"), 1);
+
+ // The ⁉ character is above DOUBLE_WIDTH_CUTOFF.
+ #[cfg(not(feature = "unicode-width"))]
+ assert_eq!(display_width("⁉"), 2);
+ }
+
+ #[test]
+ fn display_width_narrow_emojis_variant_selector() {
+ #[cfg(feature = "unicode-width")]
+ assert_eq!(display_width("⁉\u{fe0f}"), 1);
+
+ // The variant selector-16 is also counted.
+ #[cfg(not(feature = "unicode-width"))]
+ assert_eq!(display_width("⁉\u{fe0f}"), 4);
+ }
+
+ #[test]
+ fn display_width_emojis() {
+ assert_eq!(display_width("😂😭🥺🤣✨😍🙏🥰😊🔥"), 20);
+ }
+}