--- /dev/null
+//! Format list-like expressions and items.
+
+use std::cmp;
+use std::iter::Peekable;
+
+use rustc_span::BytePos;
+
+use crate::comment::{find_comment_end, rewrite_comment, FindUncommented};
+use crate::config::lists::*;
+use crate::config::{Config, IndentStyle};
+use crate::rewrite::RewriteContext;
+use crate::shape::{Indent, Shape};
+use crate::utils::{
+ count_newlines, first_line_width, last_line_width, mk_sp, starts_with_newline,
+ unicode_str_width,
+};
+use crate::visitor::SnippetProvider;
+
+pub(crate) struct ListFormatting<'a> {
+ tactic: DefinitiveListTactic,
+ separator: &'a str,
+ trailing_separator: SeparatorTactic,
+ separator_place: SeparatorPlace,
+ shape: Shape,
+ // Non-expressions, e.g., items, will have a new line at the end of the list.
+ // Important for comment styles.
+ ends_with_newline: bool,
+ // Remove newlines between list elements for expressions.
+ preserve_newline: bool,
+ // Nested import lists get some special handling for the "Mixed" list type
+ nested: bool,
+ // Whether comments should be visually aligned.
+ align_comments: bool,
+ config: &'a Config,
+}
+
+impl<'a> ListFormatting<'a> {
+ pub(crate) fn new(shape: Shape, config: &'a Config) -> Self {
+ ListFormatting {
+ tactic: DefinitiveListTactic::Vertical,
+ separator: ",",
+ trailing_separator: SeparatorTactic::Never,
+ separator_place: SeparatorPlace::Back,
+ shape,
+ ends_with_newline: true,
+ preserve_newline: false,
+ nested: false,
+ align_comments: true,
+ config,
+ }
+ }
+
+ pub(crate) fn tactic(mut self, tactic: DefinitiveListTactic) -> Self {
+ self.tactic = tactic;
+ self
+ }
+
+ pub(crate) fn separator(mut self, separator: &'a str) -> Self {
+ self.separator = separator;
+ self
+ }
+
+ pub(crate) fn trailing_separator(mut self, trailing_separator: SeparatorTactic) -> Self {
+ self.trailing_separator = trailing_separator;
+ self
+ }
+
+ pub(crate) fn separator_place(mut self, separator_place: SeparatorPlace) -> Self {
+ self.separator_place = separator_place;
+ self
+ }
+
+ pub(crate) fn ends_with_newline(mut self, ends_with_newline: bool) -> Self {
+ self.ends_with_newline = ends_with_newline;
+ self
+ }
+
+ pub(crate) fn preserve_newline(mut self, preserve_newline: bool) -> Self {
+ self.preserve_newline = preserve_newline;
+ self
+ }
+
+ pub(crate) fn nested(mut self, nested: bool) -> Self {
+ self.nested = nested;
+ self
+ }
+
+ pub(crate) fn align_comments(mut self, align_comments: bool) -> Self {
+ self.align_comments = align_comments;
+ self
+ }
+
+ pub(crate) fn needs_trailing_separator(&self) -> bool {
+ match self.trailing_separator {
+ // We always put separator in front.
+ SeparatorTactic::Always => true,
+ SeparatorTactic::Vertical => self.tactic == DefinitiveListTactic::Vertical,
+ SeparatorTactic::Never => {
+ self.tactic == DefinitiveListTactic::Vertical && self.separator_place.is_front()
+ }
+ }
+ }
+}
+
+impl AsRef<ListItem> for ListItem {
+ fn as_ref(&self) -> &ListItem {
+ self
+ }
+}
+
+#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+pub(crate) enum ListItemCommentStyle {
+ // Try to keep the comment on the same line with the item.
+ SameLine,
+ // Put the comment on the previous or the next line of the item.
+ DifferentLine,
+ // No comment available.
+ None,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ListItem {
+ // None for comments mean that they are not present.
+ pub(crate) pre_comment: Option<String>,
+ pub(crate) pre_comment_style: ListItemCommentStyle,
+ // Item should include attributes and doc comments. None indicates a failed
+ // rewrite.
+ pub(crate) item: Option<String>,
+ pub(crate) post_comment: Option<String>,
+ // Whether there is extra whitespace before this item.
+ pub(crate) new_lines: bool,
+}
+
+impl ListItem {
+ pub(crate) fn empty() -> ListItem {
+ ListItem {
+ pre_comment: None,
+ pre_comment_style: ListItemCommentStyle::None,
+ item: None,
+ post_comment: None,
+ new_lines: false,
+ }
+ }
+
+ pub(crate) fn inner_as_ref(&self) -> &str {
+ self.item.as_ref().map_or("", |s| s)
+ }
+
+ pub(crate) fn is_different_group(&self) -> bool {
+ self.inner_as_ref().contains('\n')
+ || self.pre_comment.is_some()
+ || self
+ .post_comment
+ .as_ref()
+ .map_or(false, |s| s.contains('\n'))
+ }
+
+ pub(crate) fn is_multiline(&self) -> bool {
+ self.inner_as_ref().contains('\n')
+ || self
+ .pre_comment
+ .as_ref()
+ .map_or(false, |s| s.contains('\n'))
+ || self
+ .post_comment
+ .as_ref()
+ .map_or(false, |s| s.contains('\n'))
+ }
+
+ pub(crate) fn has_single_line_comment(&self) -> bool {
+ self.pre_comment
+ .as_ref()
+ .map_or(false, |comment| comment.trim_start().starts_with("//"))
+ || self
+ .post_comment
+ .as_ref()
+ .map_or(false, |comment| comment.trim_start().starts_with("//"))
+ }
+
+ pub(crate) fn has_comment(&self) -> bool {
+ self.pre_comment.is_some() || self.post_comment.is_some()
+ }
+
+ pub(crate) fn from_str<S: Into<String>>(s: S) -> ListItem {
+ ListItem {
+ pre_comment: None,
+ pre_comment_style: ListItemCommentStyle::None,
+ item: Some(s.into()),
+ post_comment: None,
+ new_lines: false,
+ }
+ }
+
+ // Returns `true` if the item causes something to be written.
+ fn is_substantial(&self) -> bool {
+ fn empty(s: &Option<String>) -> bool {
+ match *s {
+ Some(ref s) if !s.is_empty() => false,
+ _ => true,
+ }
+ }
+
+ !(empty(&self.pre_comment) && empty(&self.item) && empty(&self.post_comment))
+ }
+}
+
+/// The type of separator for lists.
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+pub(crate) enum Separator {
+ Comma,
+ VerticalBar,
+}
+
+impl Separator {
+ pub(crate) fn len(self) -> usize {
+ match self {
+ // 2 = `, `
+ Separator::Comma => 2,
+ // 3 = ` | `
+ Separator::VerticalBar => 3,
+ }
+ }
+}
+
+pub(crate) fn definitive_tactic<I, T>(
+ items: I,
+ tactic: ListTactic,
+ sep: Separator,
+ width: usize,
+) -> DefinitiveListTactic
+where
+ I: IntoIterator<Item = T> + Clone,
+ T: AsRef<ListItem>,
+{
+ let pre_line_comments = items
+ .clone()
+ .into_iter()
+ .any(|item| item.as_ref().has_single_line_comment());
+
+ let limit = match tactic {
+ _ if pre_line_comments => return DefinitiveListTactic::Vertical,
+ ListTactic::Horizontal => return DefinitiveListTactic::Horizontal,
+ ListTactic::Vertical => return DefinitiveListTactic::Vertical,
+ ListTactic::LimitedHorizontalVertical(limit) => ::std::cmp::min(width, limit),
+ ListTactic::Mixed | ListTactic::HorizontalVertical => width,
+ };
+
+ let (sep_count, total_width) = calculate_width(items.clone());
+ let total_sep_len = sep.len() * sep_count.saturating_sub(1);
+ let real_total = total_width + total_sep_len;
+
+ if real_total <= limit && !items.into_iter().any(|item| item.as_ref().is_multiline()) {
+ DefinitiveListTactic::Horizontal
+ } else {
+ match tactic {
+ ListTactic::Mixed => DefinitiveListTactic::Mixed,
+ _ => DefinitiveListTactic::Vertical,
+ }
+ }
+}
+
+// Format a list of commented items into a string.
+pub(crate) fn write_list<I, T>(items: I, formatting: &ListFormatting<'_>) -> Option<String>
+where
+ I: IntoIterator<Item = T> + Clone,
+ T: AsRef<ListItem>,
+{
+ let tactic = formatting.tactic;
+ let sep_len = formatting.separator.len();
+
+ // Now that we know how we will layout, we can decide for sure if there
+ // will be a trailing separator.
+ let mut trailing_separator = formatting.needs_trailing_separator();
+ let mut result = String::with_capacity(128);
+ let cloned_items = items.clone();
+ let mut iter = items.into_iter().enumerate().peekable();
+ let mut item_max_width: Option<usize> = None;
+ let sep_place =
+ SeparatorPlace::from_tactic(formatting.separator_place, tactic, formatting.separator);
+ let mut prev_item_had_post_comment = false;
+ let mut prev_item_is_nested_import = false;
+
+ let mut line_len = 0;
+ let indent_str = &formatting.shape.indent.to_string(formatting.config);
+ while let Some((i, item)) = iter.next() {
+ let item = item.as_ref();
+ let inner_item = item.item.as_ref()?;
+ let first = i == 0;
+ let last = iter.peek().is_none();
+ let mut separate = match sep_place {
+ SeparatorPlace::Front => !first,
+ SeparatorPlace::Back => !last || trailing_separator,
+ };
+ let item_sep_len = if separate { sep_len } else { 0 };
+
+ // Item string may be multi-line. Its length (used for block comment alignment)
+ // should be only the length of the last line.
+ let item_last_line = if item.is_multiline() {
+ inner_item.lines().last().unwrap_or("")
+ } else {
+ inner_item.as_ref()
+ };
+ let mut item_last_line_width = item_last_line.len() + item_sep_len;
+ if item_last_line.starts_with(&**indent_str) {
+ item_last_line_width -= indent_str.len();
+ }
+
+ if !item.is_substantial() {
+ continue;
+ }
+
+ match tactic {
+ DefinitiveListTactic::Horizontal if !first => {
+ result.push(' ');
+ }
+ DefinitiveListTactic::SpecialMacro(num_args_before) => {
+ if i == 0 {
+ // Nothing
+ } else if i < num_args_before {
+ result.push(' ');
+ } else if i <= num_args_before + 1 {
+ result.push('\n');
+ result.push_str(indent_str);
+ } else {
+ result.push(' ');
+ }
+ }
+ DefinitiveListTactic::Vertical
+ if !first && !inner_item.is_empty() && !result.is_empty() =>
+ {
+ result.push('\n');
+ result.push_str(indent_str);
+ }
+ DefinitiveListTactic::Mixed => {
+ let total_width = total_item_width(item) + item_sep_len;
+
+ // 1 is space between separator and item.
+ if (line_len > 0 && line_len + 1 + total_width > formatting.shape.width)
+ || prev_item_had_post_comment
+ || (formatting.nested
+ && (prev_item_is_nested_import || (!first && inner_item.contains("::"))))
+ {
+ result.push('\n');
+ result.push_str(indent_str);
+ line_len = 0;
+ if formatting.ends_with_newline {
+ trailing_separator = true;
+ }
+ } else if line_len > 0 {
+ result.push(' ');
+ line_len += 1;
+ }
+
+ if last && formatting.ends_with_newline {
+ separate = formatting.trailing_separator != SeparatorTactic::Never;
+ }
+
+ line_len += total_width;
+ }
+ _ => {}
+ }
+
+ // Pre-comments
+ if let Some(ref comment) = item.pre_comment {
+ // Block style in non-vertical mode.
+ let block_mode = tactic == DefinitiveListTactic::Horizontal;
+ // Width restriction is only relevant in vertical mode.
+ let comment =
+ rewrite_comment(comment, block_mode, formatting.shape, formatting.config)?;
+ result.push_str(&comment);
+
+ if !inner_item.is_empty() {
+ if tactic == DefinitiveListTactic::Vertical || tactic == DefinitiveListTactic::Mixed
+ {
+ // We cannot keep pre-comments on the same line if the comment if normalized.
+ let keep_comment = if formatting.config.normalize_comments()
+ || item.pre_comment_style == ListItemCommentStyle::DifferentLine
+ {
+ false
+ } else {
+ // We will try to keep the comment on the same line with the item here.
+ // 1 = ` `
+ let total_width = total_item_width(item) + item_sep_len + 1;
+ total_width <= formatting.shape.width
+ };
+ if keep_comment {
+ result.push(' ');
+ } else {
+ result.push('\n');
+ result.push_str(indent_str);
+ // This is the width of the item (without comments).
+ line_len = item.item.as_ref().map_or(0, |s| unicode_str_width(&s));
+ }
+ } else {
+ result.push(' ');
+ }
+ }
+ item_max_width = None;
+ }
+
+ if separate && sep_place.is_front() && !first {
+ result.push_str(formatting.separator.trim());
+ result.push(' ');
+ }
+ result.push_str(inner_item);
+
+ // Post-comments
+ if tactic == DefinitiveListTactic::Horizontal && item.post_comment.is_some() {
+ let comment = item.post_comment.as_ref().unwrap();
+ let formatted_comment = rewrite_comment(
+ comment,
+ true,
+ Shape::legacy(formatting.shape.width, Indent::empty()),
+ formatting.config,
+ )?;
+
+ result.push(' ');
+ result.push_str(&formatted_comment);
+ }
+
+ if separate && sep_place.is_back() {
+ result.push_str(formatting.separator);
+ }
+
+ if tactic != DefinitiveListTactic::Horizontal && item.post_comment.is_some() {
+ let comment = item.post_comment.as_ref().unwrap();
+ let overhead = last_line_width(&result) + first_line_width(comment.trim());
+
+ let rewrite_post_comment = |item_max_width: &mut Option<usize>| {
+ if item_max_width.is_none() && !last && !inner_item.contains('\n') {
+ *item_max_width = Some(max_width_of_item_with_post_comment(
+ &cloned_items,
+ i,
+ overhead,
+ formatting.config.max_width(),
+ ));
+ }
+ let overhead = if starts_with_newline(comment) {
+ 0
+ } else if let Some(max_width) = *item_max_width {
+ max_width + 2
+ } else {
+ // 1 = space between item and comment.
+ item_last_line_width + 1
+ };
+ let width = formatting.shape.width.checked_sub(overhead).unwrap_or(1);
+ let offset = formatting.shape.indent + overhead;
+ let comment_shape = Shape::legacy(width, offset);
+
+ // Use block-style only for the last item or multiline comments.
+ let block_style = !formatting.ends_with_newline && last
+ || comment.trim().contains('\n')
+ || comment.trim().len() > width;
+
+ rewrite_comment(
+ comment.trim_start(),
+ block_style,
+ comment_shape,
+ formatting.config,
+ )
+ };
+
+ let mut formatted_comment = rewrite_post_comment(&mut item_max_width)?;
+
+ if !starts_with_newline(comment) {
+ if formatting.align_comments {
+ let mut comment_alignment =
+ post_comment_alignment(item_max_width, inner_item.len());
+ if first_line_width(&formatted_comment)
+ + last_line_width(&result)
+ + comment_alignment
+ + 1
+ > formatting.config.max_width()
+ {
+ item_max_width = None;
+ formatted_comment = rewrite_post_comment(&mut item_max_width)?;
+ comment_alignment =
+ post_comment_alignment(item_max_width, inner_item.len());
+ }
+ for _ in 0..=comment_alignment {
+ result.push(' ');
+ }
+ }
+ // An additional space for the missing trailing separator (or
+ // if we skipped alignment above).
+ if !formatting.align_comments
+ || (last
+ && item_max_width.is_some()
+ && !separate
+ && !formatting.separator.is_empty())
+ {
+ result.push(' ');
+ }
+ } else {
+ result.push('\n');
+ result.push_str(indent_str);
+ }
+ if formatted_comment.contains('\n') {
+ item_max_width = None;
+ }
+ result.push_str(&formatted_comment);
+ } else {
+ item_max_width = None;
+ }
+
+ if formatting.preserve_newline
+ && !last
+ && tactic == DefinitiveListTactic::Vertical
+ && item.new_lines
+ {
+ item_max_width = None;
+ result.push('\n');
+ }
+
+ prev_item_had_post_comment = item.post_comment.is_some();
+ prev_item_is_nested_import = inner_item.contains("::");
+ }
+
+ Some(result)
+}
+
+fn max_width_of_item_with_post_comment<I, T>(
+ items: &I,
+ i: usize,
+ overhead: usize,
+ max_budget: usize,
+) -> usize
+where
+ I: IntoIterator<Item = T> + Clone,
+ T: AsRef<ListItem>,
+{
+ let mut max_width = 0;
+ let mut first = true;
+ for item in items.clone().into_iter().skip(i) {
+ let item = item.as_ref();
+ let inner_item_width = item.inner_as_ref().len();
+ if !first
+ && (item.is_different_group()
+ || item.post_comment.is_none()
+ || inner_item_width + overhead > max_budget)
+ {
+ return max_width;
+ }
+ if max_width < inner_item_width {
+ max_width = inner_item_width;
+ }
+ if item.new_lines {
+ return max_width;
+ }
+ first = false;
+ }
+ max_width
+}
+
+fn post_comment_alignment(item_max_width: Option<usize>, inner_item_len: usize) -> usize {
+ item_max_width.unwrap_or(0).saturating_sub(inner_item_len)
+}
+
+pub(crate) struct ListItems<'a, I, F1, F2, F3>
+where
+ I: Iterator,
+{
+ snippet_provider: &'a SnippetProvider,
+ inner: Peekable<I>,
+ get_lo: F1,
+ get_hi: F2,
+ get_item_string: F3,
+ prev_span_end: BytePos,
+ next_span_start: BytePos,
+ terminator: &'a str,
+ separator: &'a str,
+ leave_last: bool,
+}
+
+pub(crate) fn extract_pre_comment(pre_snippet: &str) -> (Option<String>, ListItemCommentStyle) {
+ let trimmed_pre_snippet = pre_snippet.trim();
+ // Both start and end are checked to support keeping a block comment inline with
+ // the item, even if there are preceeding line comments, while still supporting
+ // a snippet that starts with a block comment but also contains one or more
+ // trailing single line comments.
+ // https://github.com/rust-lang/rustfmt/issues/3025
+ // https://github.com/rust-lang/rustfmt/pull/3048
+ // https://github.com/rust-lang/rustfmt/issues/3839
+ let starts_with_block_comment = trimmed_pre_snippet.starts_with("/*");
+ let ends_with_block_comment = trimmed_pre_snippet.ends_with("*/");
+ let starts_with_single_line_comment = trimmed_pre_snippet.starts_with("//");
+ if ends_with_block_comment {
+ let comment_end = pre_snippet.rfind(|c| c == '/').unwrap();
+ if pre_snippet[comment_end..].contains('\n') {
+ (
+ Some(trimmed_pre_snippet.to_owned()),
+ ListItemCommentStyle::DifferentLine,
+ )
+ } else {
+ (
+ Some(trimmed_pre_snippet.to_owned()),
+ ListItemCommentStyle::SameLine,
+ )
+ }
+ } else if starts_with_single_line_comment || starts_with_block_comment {
+ (
+ Some(trimmed_pre_snippet.to_owned()),
+ ListItemCommentStyle::DifferentLine,
+ )
+ } else {
+ (None, ListItemCommentStyle::None)
+ }
+}
+
+pub(crate) fn extract_post_comment(
+ post_snippet: &str,
+ comment_end: usize,
+ separator: &str,
+) -> Option<String> {
+ let white_space: &[_] = &[' ', '\t'];
+
+ // Cleanup post-comment: strip separators and whitespace.
+ let post_snippet = post_snippet[..comment_end].trim();
+ let post_snippet_trimmed = if post_snippet.starts_with(|c| c == ',' || c == ':') {
+ post_snippet[1..].trim_matches(white_space)
+ } else if post_snippet.starts_with(separator) {
+ post_snippet[separator.len()..].trim_matches(white_space)
+ }
+ // not comment or over two lines
+ else if post_snippet.ends_with(',')
+ && (!post_snippet.trim().starts_with("//") || post_snippet.trim().contains('\n'))
+ {
+ post_snippet[..(post_snippet.len() - 1)].trim_matches(white_space)
+ } else {
+ post_snippet
+ };
+ // FIXME(#3441): post_snippet includes 'const' now
+ // it should not include here
+ let removed_newline_snippet = post_snippet_trimmed.trim();
+ if !post_snippet_trimmed.is_empty()
+ && (removed_newline_snippet.starts_with("//") || removed_newline_snippet.starts_with("/*"))
+ {
+ Some(post_snippet_trimmed.to_owned())
+ } else {
+ None
+ }
+}
+
+pub(crate) fn get_comment_end(
+ post_snippet: &str,
+ separator: &str,
+ terminator: &str,
+ is_last: bool,
+) -> usize {
+ if is_last {
+ return post_snippet
+ .find_uncommented(terminator)
+ .unwrap_or_else(|| post_snippet.len());
+ }
+
+ let mut block_open_index = post_snippet.find("/*");
+ // check if it really is a block comment (and not `//*` or a nested comment)
+ if let Some(i) = block_open_index {
+ match post_snippet.find('/') {
+ Some(j) if j < i => block_open_index = None,
+ _ if post_snippet[..i].ends_with('/') => block_open_index = None,
+ _ => (),
+ }
+ }
+ let newline_index = post_snippet.find('\n');
+ if let Some(separator_index) = post_snippet.find_uncommented(separator) {
+ match (block_open_index, newline_index) {
+ // Separator before comment, with the next item on same line.
+ // Comment belongs to next item.
+ (Some(i), None) if i > separator_index => separator_index + 1,
+ // Block-style post-comment before the separator.
+ (Some(i), None) => cmp::max(
+ find_comment_end(&post_snippet[i..]).unwrap() + i,
+ separator_index + 1,
+ ),
+ // Block-style post-comment. Either before or after the separator.
+ (Some(i), Some(j)) if i < j => cmp::max(
+ find_comment_end(&post_snippet[i..]).unwrap() + i,
+ separator_index + 1,
+ ),
+ // Potential *single* line comment.
+ (_, Some(j)) if j > separator_index => j + 1,
+ _ => post_snippet.len(),
+ }
+ } else if let Some(newline_index) = newline_index {
+ // Match arms may not have trailing comma. In any case, for match arms,
+ // we will assume that the post comment belongs to the next arm if they
+ // do not end with trailing comma.
+ newline_index + 1
+ } else {
+ 0
+ }
+}
+
+// Account for extra whitespace between items. This is fiddly
+// because of the way we divide pre- and post- comments.
+pub(crate) fn has_extra_newline(post_snippet: &str, comment_end: usize) -> bool {
+ if post_snippet.is_empty() || comment_end == 0 {
+ return false;
+ }
+
+ let len_last = post_snippet[..comment_end]
+ .chars()
+ .last()
+ .unwrap()
+ .len_utf8();
+ // Everything from the separator to the next item.
+ let test_snippet = &post_snippet[comment_end - len_last..];
+ let first_newline = test_snippet
+ .find('\n')
+ .unwrap_or_else(|| test_snippet.len());
+ // From the end of the first line of comments.
+ let test_snippet = &test_snippet[first_newline..];
+ let first = test_snippet
+ .find(|c: char| !c.is_whitespace())
+ .unwrap_or_else(|| test_snippet.len());
+ // From the end of the first line of comments to the next non-whitespace char.
+ let test_snippet = &test_snippet[..first];
+
+ // There were multiple line breaks which got trimmed to nothing.
+ count_newlines(test_snippet) > 1
+}
+
+impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
+where
+ I: Iterator<Item = T>,
+ F1: Fn(&T) -> BytePos,
+ F2: Fn(&T) -> BytePos,
+ F3: Fn(&T) -> Option<String>,
+{
+ type Item = ListItem;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner.next().map(|item| {
+ // Pre-comment
+ let pre_snippet = self
+ .snippet_provider
+ .span_to_snippet(mk_sp(self.prev_span_end, (self.get_lo)(&item)))
+ .unwrap_or("");
+ let (pre_comment, pre_comment_style) = extract_pre_comment(pre_snippet);
+
+ // Post-comment
+ let next_start = match self.inner.peek() {
+ Some(next_item) => (self.get_lo)(next_item),
+ None => self.next_span_start,
+ };
+ let post_snippet = self
+ .snippet_provider
+ .span_to_snippet(mk_sp((self.get_hi)(&item), next_start))
+ .unwrap_or("");
+ let comment_end = get_comment_end(
+ post_snippet,
+ self.separator,
+ self.terminator,
+ self.inner.peek().is_none(),
+ );
+ let new_lines = has_extra_newline(post_snippet, comment_end);
+ let post_comment = extract_post_comment(post_snippet, comment_end, self.separator);
+
+ self.prev_span_end = (self.get_hi)(&item) + BytePos(comment_end as u32);
+
+ ListItem {
+ pre_comment,
+ pre_comment_style,
+ item: if self.inner.peek().is_none() && self.leave_last {
+ None
+ } else {
+ (self.get_item_string)(&item)
+ },
+ post_comment,
+ new_lines,
+ }
+ })
+ }
+}
+
+#[allow(clippy::too_many_arguments)]
+// Creates an iterator over a list's items with associated comments.
+pub(crate) fn itemize_list<'a, T, I, F1, F2, F3>(
+ snippet_provider: &'a SnippetProvider,
+ inner: I,
+ terminator: &'a str,
+ separator: &'a str,
+ get_lo: F1,
+ get_hi: F2,
+ get_item_string: F3,
+ prev_span_end: BytePos,
+ next_span_start: BytePos,
+ leave_last: bool,
+) -> ListItems<'a, I, F1, F2, F3>
+where
+ I: Iterator<Item = T>,
+ F1: Fn(&T) -> BytePos,
+ F2: Fn(&T) -> BytePos,
+ F3: Fn(&T) -> Option<String>,
+{
+ ListItems {
+ snippet_provider,
+ inner: inner.peekable(),
+ get_lo,
+ get_hi,
+ get_item_string,
+ prev_span_end,
+ next_span_start,
+ terminator,
+ separator,
+ leave_last,
+ }
+}
+
+/// Returns the count and total width of the list items.
+fn calculate_width<I, T>(items: I) -> (usize, usize)
+where
+ I: IntoIterator<Item = T>,
+ T: AsRef<ListItem>,
+{
+ items
+ .into_iter()
+ .map(|item| total_item_width(item.as_ref()))
+ .fold((0, 0), |acc, l| (acc.0 + 1, acc.1 + l))
+}
+
+pub(crate) fn total_item_width(item: &ListItem) -> usize {
+ comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..]))
+ + comment_len(item.post_comment.as_ref().map(|x| &(*x)[..]))
+ + &item.item.as_ref().map_or(0, |s| unicode_str_width(&s))
+}
+
+fn comment_len(comment: Option<&str>) -> usize {
+ match comment {
+ Some(s) => {
+ let text_len = s.trim().len();
+ if text_len > 0 {
+ // We'll put " /*" before and " */" after inline comments.
+ text_len + 6
+ } else {
+ text_len
+ }
+ }
+ None => 0,
+ }
+}
+
+// Compute horizontal and vertical shapes for a struct-lit-like thing.
+pub(crate) fn struct_lit_shape(
+ shape: Shape,
+ context: &RewriteContext<'_>,
+ prefix_width: usize,
+ suffix_width: usize,
+) -> Option<(Option<Shape>, Shape)> {
+ let v_shape = match context.config.indent_style() {
+ IndentStyle::Visual => shape
+ .visual_indent(0)
+ .shrink_left(prefix_width)?
+ .sub_width(suffix_width)?,
+ IndentStyle::Block => {
+ let shape = shape.block_indent(context.config.tab_spaces());
+ Shape {
+ width: context.budget(shape.indent.width()),
+ ..shape
+ }
+ }
+ };
+ let shape_width = shape.width.checked_sub(prefix_width + suffix_width);
+ if let Some(w) = shape_width {
+ let shape_width = cmp::min(w, context.config.width_heuristics().struct_lit_width);
+ Some((Some(Shape::legacy(shape_width, shape.indent)), v_shape))
+ } else {
+ Some((None, v_shape))
+ }
+}
+
+// Compute the tactic for the internals of a struct-lit-like thing.
+pub(crate) fn struct_lit_tactic(
+ h_shape: Option<Shape>,
+ context: &RewriteContext<'_>,
+ items: &[ListItem],
+) -> DefinitiveListTactic {
+ if let Some(h_shape) = h_shape {
+ let prelim_tactic = match (context.config.indent_style(), items.len()) {
+ (IndentStyle::Visual, 1) => ListTactic::HorizontalVertical,
+ _ if context.config.struct_lit_single_line() => ListTactic::HorizontalVertical,
+ _ => ListTactic::Vertical,
+ };
+ definitive_tactic(items, prelim_tactic, Separator::Comma, h_shape.width)
+ } else {
+ DefinitiveListTactic::Vertical
+ }
+}
+
+// Given a tactic and possible shapes for horizontal and vertical layout,
+// come up with the actual shape to use.
+pub(crate) fn shape_for_tactic(
+ tactic: DefinitiveListTactic,
+ h_shape: Option<Shape>,
+ v_shape: Shape,
+) -> Shape {
+ match tactic {
+ DefinitiveListTactic::Horizontal => h_shape.unwrap(),
+ _ => v_shape,
+ }
+}
+
+// Create a ListFormatting object for formatting the internals of a
+// struct-lit-like thing, that is a series of fields.
+pub(crate) fn struct_lit_formatting<'a>(
+ shape: Shape,
+ tactic: DefinitiveListTactic,
+ context: &'a RewriteContext<'_>,
+ force_no_trailing_comma: bool,
+) -> ListFormatting<'a> {
+ let ends_with_newline = context.config.indent_style() != IndentStyle::Visual
+ && tactic == DefinitiveListTactic::Vertical;
+ ListFormatting {
+ tactic,
+ separator: ",",
+ trailing_separator: if force_no_trailing_comma {
+ SeparatorTactic::Never
+ } else {
+ context.config.trailing_comma()
+ },
+ separator_place: SeparatorPlace::Back,
+ shape,
+ ends_with_newline,
+ preserve_newline: true,
+ nested: false,
+ align_comments: true,
+ config: context.config,
+ }
+}
projects / rustc.git / blobdiff