Attempt to auto-detect indentation style on document load.
This also moves the primary indentation-style setting into Document.
This commit is contained in:
Nathan Vegdahl
parent
1bda454149
commit
2329512122
1 changed files with 196 additions and 5 deletions
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@ -21,11 +21,18 @@ pub enum Mode {
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Insert,
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}
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#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
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pub enum IndentStyle {
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Tabs,
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Spaces(u8),
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}
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pub struct Document {
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// rope + selection
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pub(crate) id: DocumentId,
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text: Rope,
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pub(crate) selections: HashMap<ViewId, Selection>,
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pub(crate) indent_style: IndentStyle,
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path: Option<PathBuf>,
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@ -149,6 +156,7 @@ impl Document {
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path: None,
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text,
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selections: HashMap::default(),
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indent_style: IndentStyle::Spaces(4),
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mode: Mode::Normal,
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restore_cursor: false,
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syntax: None,
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@ -182,6 +190,7 @@ impl Document {
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let mut doc = Self::new(doc);
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// set the path and try detecting the language
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doc.set_path(&path)?;
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doc.detect_indent_style();
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Ok(doc)
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}
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@ -265,6 +274,176 @@ impl Document {
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}
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}
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fn detect_indent_style(&mut self) {
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// Determine whether a character is a line break.
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//
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// TODO: this is probably a generally useful utility function. Where
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// should we put it?
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fn char_is_linebreak(c: char) -> bool {
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match c {
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'\u{000A}' | // LineFeed
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'\u{000B}' | // VerticalTab
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'\u{000C}' | // FormFeed
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'\u{000D}' | // CarriageReturn
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'\u{0085}' | // NextLine
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'\u{2028}' | // Line Separator
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'\u{2029}' // ParagraphSeparator
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=> true,
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_ => false,
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}
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}
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// Determine whether a character qualifies as (non-line-break)
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// whitespace.
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//
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// TODO: this is probably a generally useful utility function. Where
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// should we put it?
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//
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// TODO: this is a naive binary categorization of whitespace
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// characters. For display, word wrapping, etc. we'll need a better
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// categorization based on e.g. breaking vs non-breaking spaces
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// and whether they're zero-width or not.
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pub fn char_is_whitespace(c: char) -> bool {
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match c {
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//'\u{1680}' | // Ogham Space Mark (here for completeness, but usually displayed as a dash, not as whitespace)
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'\u{0009}' | // Character Tabulation
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'\u{0020}' | // Space
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'\u{00A0}' | // No-break Space
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'\u{180E}' | // Mongolian Vowel Separator
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'\u{202F}' | // Narrow No-break Space
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'\u{205F}' | // Medium Mathematical Space
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'\u{3000}' | // Ideographic Space
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'\u{FEFF}' // Zero Width No-break Space
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=> true,
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// En Quad, Em Quad, En Space, Em Space, Three-per-em Space,
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// Four-per-em Space, Six-per-em Space, Figure Space,
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// Punctuation Space, Thin Space, Hair Space, Zero Width Space.
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c if c >= '\u{2000}' && c <= '\u{200B}' => true,
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_ => false,
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}
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}
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// Build a histogram of the indentation *increases* between
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// subsequent lines, ignoring lines that are all whitespace.
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//
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// Index 0 is for tabs, the rest are 1-8 spaces.
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let histogram: [usize; 9] = {
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let mut histogram = [0; 9];
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let mut prev_line_indent = (false, 0usize); // (was_tabs, count)
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'outer: for line in self.text.lines().take(1000) {
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let mut c_iter = line.chars();
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// Is first character a tab or space?
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let is_tabs = match c_iter.next() {
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Some('\t') => true,
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Some(' ') => false,
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// Ignore blank lines.
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Some(c) if char_is_linebreak(c) => continue 'outer,
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_ => {
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prev_line_indent = (false, 0usize);
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continue 'outer;
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}
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};
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// Count the total leading tab/space characters.
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let mut count = 1;
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let mut count_is_done = false;
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for c in c_iter {
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match c {
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'\t' if is_tabs && !count_is_done => count += 1,
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' ' if !is_tabs && !count_is_done => count += 1,
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// We stop counting if we hit whitespace that doesn't
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// qualify as indent or doesn't match the leading
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// whitespace, but we don't exit the loop yet because
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// we still want to determine if the line is blank.
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c if char_is_whitespace(c) => count_is_done = true,
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// Ignore blank lines.
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c if char_is_linebreak(c) => continue 'outer,
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_ => break,
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}
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// Bound the worst-case execution time for weird text files.
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if count > 256 {
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continue 'outer;
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}
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}
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// Update stats.
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if (prev_line_indent.0 == is_tabs || prev_line_indent.1 == 0)
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&& prev_line_indent.1 < count
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{
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if is_tabs {
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histogram[0] += 1;
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} else {
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let amount = count - prev_line_indent.1;
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if amount <= 8 {
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histogram[amount] += 1;
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}
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}
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}
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// Store data for use with the next line.
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prev_line_indent = (is_tabs, count);
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}
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// Give more weight to tabs, because their presence is a very
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// strong indicator.
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histogram[0] *= 2;
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histogram
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};
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// Find the most frequent indent, its frequency, and the frequency of
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// the next-most frequent indent.
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let indent = histogram
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.iter()
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.enumerate()
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.max_by_key(|kv| kv.1)
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.unwrap()
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.0;
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let indent_freq = histogram[indent];
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let indent_freq_2 = *histogram
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.iter()
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.enumerate()
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.filter(|kv| kv.0 != indent)
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.map(|kv| kv.1)
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.max()
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.unwrap();
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// Use the auto-detected result if we're confident enough in its
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// accuracy, based on some heuristics. Otherwise fall back to
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// the language-based setting.
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if indent_freq >= 1 && (indent_freq_2 as f64 / indent_freq as f64) < 0.66 {
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// Use the auto-detected setting.
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self.indent_style = match indent {
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0 => IndentStyle::Tabs,
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_ => IndentStyle::Spaces(indent as u8),
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};
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} else {
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// Fall back to language-based setting.
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let indent = self
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.language
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.as_ref()
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.and_then(|config| config.indent.as_ref())
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.map_or(" ", |config| config.unit.as_str()); // fallback to 2 spaces
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self.indent_style = if indent.starts_with(" ") {
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IndentStyle::Spaces(indent.len() as u8)
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} else {
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IndentStyle::Tabs
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};
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}
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}
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pub fn set_path(&mut self, path: &Path) -> Result<(), std::io::Error> {
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let path = canonicalize_path(path)?;
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@ -507,13 +686,25 @@ impl Document {
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}
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/// Returns a string containing a single level of indentation.
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///
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/// TODO: we might not need this function anymore, since the information
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/// is conveniently available in `Document::indent_style` now.
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pub fn indent_unit(&self) -> &str {
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self.language
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.as_ref()
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.and_then(|config| config.indent.as_ref())
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.map_or(" ", |config| config.unit.as_str()) // fallback to 2 spaces
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match self.indent_style {
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IndentStyle::Tabs => "\t",
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IndentStyle::Spaces(1) => " ",
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IndentStyle::Spaces(2) => " ",
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IndentStyle::Spaces(3) => " ",
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IndentStyle::Spaces(4) => " ",
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IndentStyle::Spaces(5) => " ",
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IndentStyle::Spaces(6) => " ",
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IndentStyle::Spaces(7) => " ",
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IndentStyle::Spaces(8) => " ",
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// " ".repeat(TAB_WIDTH)
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// Unsupported indentation style. This should never happen,
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// but just in case fall back to two spaces.
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_ => " ",
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}
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}
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#[inline]
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