--- /dev/null
+//! Format attributes and meta items.
+
+use rustc_ast::ast;
+use rustc_ast::attr::HasAttrs;
+use rustc_span::{symbol::sym, Span, Symbol};
+
+use self::doc_comment::DocCommentFormatter;
+use crate::comment::{contains_comment, rewrite_doc_comment, CommentStyle};
+use crate::config::lists::*;
+use crate::config::IndentStyle;
+use crate::expr::rewrite_literal;
+use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
+use crate::overflow;
+use crate::rewrite::{Rewrite, RewriteContext};
+use crate::shape::Shape;
+use crate::types::{rewrite_path, PathContext};
+use crate::utils::{count_newlines, mk_sp};
+
+mod doc_comment;
+
+pub(crate) fn contains_name(attrs: &[ast::Attribute], name: Symbol) -> bool {
+ attrs.iter().any(|attr| attr.has_name(name))
+}
+
+pub(crate) fn first_attr_value_str_by_name(
+ attrs: &[ast::Attribute],
+ name: Symbol,
+) -> Option<Symbol> {
+ attrs
+ .iter()
+ .find(|attr| attr.has_name(name))
+ .and_then(|attr| attr.value_str())
+}
+
+/// Returns attributes on the given statement.
+pub(crate) fn get_attrs_from_stmt(stmt: &ast::Stmt) -> &[ast::Attribute] {
+ stmt.attrs()
+}
+
+pub(crate) fn get_span_without_attrs(stmt: &ast::Stmt) -> Span {
+ match stmt.kind {
+ ast::StmtKind::Local(ref local) => local.span,
+ ast::StmtKind::Item(ref item) => item.span,
+ ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => expr.span,
+ ast::StmtKind::MacCall(ref mac_stmt) => mac_stmt.mac.span(),
+ ast::StmtKind::Empty => stmt.span,
+ }
+}
+
+/// Returns attributes that are within `outer_span`.
+pub(crate) fn filter_inline_attrs(
+ attrs: &[ast::Attribute],
+ outer_span: Span,
+) -> Vec<ast::Attribute> {
+ attrs
+ .iter()
+ .filter(|a| outer_span.lo() <= a.span.lo() && a.span.hi() <= outer_span.hi())
+ .cloned()
+ .collect()
+}
+
+fn is_derive(attr: &ast::Attribute) -> bool {
+ attr.has_name(sym::derive)
+}
+
+// The shape of the arguments to a function-like attribute.
+fn argument_shape(
+ left: usize,
+ right: usize,
+ combine: bool,
+ shape: Shape,
+ context: &RewriteContext<'_>,
+) -> Option<Shape> {
+ match context.config.indent_style() {
+ IndentStyle::Block => {
+ if combine {
+ shape.offset_left(left)
+ } else {
+ Some(
+ shape
+ .block_indent(context.config.tab_spaces())
+ .with_max_width(context.config),
+ )
+ }
+ }
+ IndentStyle::Visual => shape
+ .visual_indent(0)
+ .shrink_left(left)
+ .and_then(|s| s.sub_width(right)),
+ }
+}
+
+fn format_derive(
+ derives: &[ast::Attribute],
+ shape: Shape,
+ context: &RewriteContext<'_>,
+) -> Option<String> {
+ // Collect all items from all attributes
+ let all_items = derives
+ .iter()
+ .map(|attr| {
+ // Parse the derive items and extract the span for each item; if any
+ // attribute is not parseable, none of the attributes will be
+ // reformatted.
+ let item_spans = attr.meta_item_list().map(|meta_item_list| {
+ meta_item_list
+ .into_iter()
+ .map(|nested_meta_item| nested_meta_item.span())
+ })?;
+
+ let items = itemize_list(
+ context.snippet_provider,
+ item_spans,
+ ")",
+ ",",
+ |span| span.lo(),
+ |span| span.hi(),
+ |span| Some(context.snippet(*span).to_owned()),
+ attr.span.lo(),
+ attr.span.hi(),
+ false,
+ );
+
+ Some(items)
+ })
+ // Fail if any attribute failed.
+ .collect::<Option<Vec<_>>>()?
+ // Collect the results into a single, flat, Vec.
+ .into_iter()
+ .flatten()
+ .collect::<Vec<_>>();
+
+ // Collect formatting parameters.
+ let prefix = attr_prefix(&derives[0]);
+ let argument_shape = argument_shape(
+ "[derive()]".len() + prefix.len(),
+ ")]".len(),
+ false,
+ shape,
+ context,
+ )?;
+ let one_line_shape = shape
+ .offset_left("[derive()]".len() + prefix.len())?
+ .sub_width("()]".len())?;
+ let one_line_budget = one_line_shape.width;
+
+ let tactic = definitive_tactic(
+ &all_items,
+ ListTactic::HorizontalVertical,
+ Separator::Comma,
+ argument_shape.width,
+ );
+ let trailing_separator = match context.config.indent_style() {
+ // We always add the trailing comma and remove it if it is not needed.
+ IndentStyle::Block => SeparatorTactic::Always,
+ IndentStyle::Visual => SeparatorTactic::Never,
+ };
+
+ // Format the collection of items.
+ let fmt = ListFormatting::new(argument_shape, context.config)
+ .tactic(tactic)
+ .trailing_separator(trailing_separator)
+ .ends_with_newline(false);
+ let item_str = write_list(&all_items, &fmt)?;
+
+ debug!("item_str: '{}'", item_str);
+
+ // Determine if the result will be nested, i.e. if we're using the block
+ // indent style and either the items are on multiple lines or we've exceeded
+ // our budget to fit on a single line.
+ let nested = context.config.indent_style() == IndentStyle::Block
+ && (item_str.contains('\n') || item_str.len() > one_line_budget);
+
+ // Format the final result.
+ let mut result = String::with_capacity(128);
+ result.push_str(prefix);
+ result.push_str("[derive(");
+ if nested {
+ let nested_indent = argument_shape.indent.to_string_with_newline(context.config);
+ result.push_str(&nested_indent);
+ result.push_str(&item_str);
+ result.push_str(&shape.indent.to_string_with_newline(context.config));
+ } else if let SeparatorTactic::Always = context.config.trailing_comma() {
+ // Retain the trailing comma.
+ result.push_str(&item_str);
+ } else if item_str.ends_with(",") {
+ // Remove the trailing comma.
+ result.push_str(&item_str[..item_str.len() - 1]);
+ } else {
+ result.push_str(&item_str);
+ }
+ result.push_str(")]");
+
+ Some(result)
+}
+
+/// Returns the first group of attributes that fills the given predicate.
+/// We consider two doc comments are in different group if they are separated by normal comments.
+fn take_while_with_pred<'a, P>(
+ context: &RewriteContext<'_>,
+ attrs: &'a [ast::Attribute],
+ pred: P,
+) -> &'a [ast::Attribute]
+where
+ P: Fn(&ast::Attribute) -> bool,
+{
+ let mut len = 0;
+ let mut iter = attrs.iter().peekable();
+
+ while let Some(attr) = iter.next() {
+ if pred(attr) {
+ len += 1;
+ } else {
+ break;
+ }
+ if let Some(next_attr) = iter.peek() {
+ // Extract comments between two attributes.
+ let span_between_attr = mk_sp(attr.span.hi(), next_attr.span.lo());
+ let snippet = context.snippet(span_between_attr);
+ if count_newlines(snippet) >= 2 || snippet.contains('/') {
+ break;
+ }
+ }
+ }
+
+ &attrs[..len]
+}
+
+/// Rewrite the any doc comments which come before any other attributes.
+fn rewrite_initial_doc_comments(
+ context: &RewriteContext<'_>,
+ attrs: &[ast::Attribute],
+ shape: Shape,
+) -> Option<(usize, Option<String>)> {
+ if attrs.is_empty() {
+ return Some((0, None));
+ }
+ // Rewrite doc comments
+ let sugared_docs = take_while_with_pred(context, attrs, |a| a.is_doc_comment());
+ if !sugared_docs.is_empty() {
+ let snippet = sugared_docs
+ .iter()
+ .map(|a| context.snippet(a.span))
+ .collect::<Vec<_>>()
+ .join("\n");
+ return Some((
+ sugared_docs.len(),
+ Some(rewrite_doc_comment(
+ &snippet,
+ shape.comment(context.config),
+ context.config,
+ )?),
+ ));
+ }
+
+ Some((0, None))
+}
+
+impl Rewrite for ast::NestedMetaItem {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ match self {
+ ast::NestedMetaItem::MetaItem(ref meta_item) => meta_item.rewrite(context, shape),
+ ast::NestedMetaItem::Literal(ref l) => rewrite_literal(context, l, shape),
+ }
+ }
+}
+
+fn has_newlines_before_after_comment(comment: &str) -> (&str, &str) {
+ // Look at before and after comment and see if there are any empty lines.
+ let comment_begin = comment.find('/');
+ let len = comment_begin.unwrap_or_else(|| comment.len());
+ let mlb = count_newlines(&comment[..len]) > 1;
+ let mla = if comment_begin.is_none() {
+ mlb
+ } else {
+ comment
+ .chars()
+ .rev()
+ .take_while(|c| c.is_whitespace())
+ .filter(|&c| c == '\n')
+ .count()
+ > 1
+ };
+ (if mlb { "\n" } else { "" }, if mla { "\n" } else { "" })
+}
+
+impl Rewrite for ast::MetaItem {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ Some(match self.kind {
+ ast::MetaItemKind::Word => {
+ rewrite_path(context, PathContext::Type, None, &self.path, shape)?
+ }
+ ast::MetaItemKind::List(ref list) => {
+ let path = rewrite_path(context, PathContext::Type, None, &self.path, shape)?;
+ let has_trailing_comma = crate::expr::span_ends_with_comma(context, self.span);
+ overflow::rewrite_with_parens(
+ context,
+ &path,
+ list.iter(),
+ // 1 = "]"
+ shape.sub_width(1)?,
+ self.span,
+ context.config.width_heuristics().attr_fn_like_width,
+ Some(if has_trailing_comma {
+ SeparatorTactic::Always
+ } else {
+ SeparatorTactic::Never
+ }),
+ )?
+ }
+ ast::MetaItemKind::NameValue(ref literal) => {
+ let path = rewrite_path(context, PathContext::Type, None, &self.path, shape)?;
+ // 3 = ` = `
+ let lit_shape = shape.shrink_left(path.len() + 3)?;
+ // `rewrite_literal` returns `None` when `literal` exceeds max
+ // width. Since a literal is basically unformattable unless it
+ // is a string literal (and only if `format_strings` is set),
+ // we might be better off ignoring the fact that the attribute
+ // is longer than the max width and continue on formatting.
+ // See #2479 for example.
+ let value = rewrite_literal(context, literal, lit_shape)
+ .unwrap_or_else(|| context.snippet(literal.span).to_owned());
+ format!("{} = {}", path, value)
+ }
+ })
+ }
+}
+
+impl Rewrite for ast::Attribute {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ let snippet = context.snippet(self.span);
+ if self.is_doc_comment() {
+ rewrite_doc_comment(snippet, shape.comment(context.config), context.config)
+ } else {
+ let should_skip = self
+ .ident()
+ .map(|s| context.skip_context.skip_attribute(&s.name.as_str()))
+ .unwrap_or(false);
+ let prefix = attr_prefix(self);
+
+ if should_skip || contains_comment(snippet) {
+ return Some(snippet.to_owned());
+ }
+
+ if let Some(ref meta) = self.meta() {
+ // This attribute is possibly a doc attribute needing normalization to a doc comment
+ if context.config.normalize_doc_attributes() && meta.has_name(sym::doc) {
+ if let Some(ref literal) = meta.value_str() {
+ let comment_style = match self.style {
+ ast::AttrStyle::Inner => CommentStyle::Doc,
+ ast::AttrStyle::Outer => CommentStyle::TripleSlash,
+ };
+
+ let literal_str = literal.as_str();
+ let doc_comment_formatter =
+ DocCommentFormatter::new(&*literal_str, comment_style);
+ let doc_comment = format!("{}", doc_comment_formatter);
+ return rewrite_doc_comment(
+ &doc_comment,
+ shape.comment(context.config),
+ context.config,
+ );
+ }
+ }
+
+ // 1 = `[`
+ let shape = shape.offset_left(prefix.len() + 1)?;
+ Some(
+ meta.rewrite(context, shape)
+ .map_or_else(|| snippet.to_owned(), |rw| format!("{}[{}]", prefix, rw)),
+ )
+ } else {
+ Some(snippet.to_owned())
+ }
+ }
+ }
+}
+
+impl<'a> Rewrite for [ast::Attribute] {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ if self.is_empty() {
+ return Some(String::new());
+ }
+
+ // The current remaining attributes.
+ let mut attrs = self;
+ let mut result = String::new();
+
+ // This is not just a simple map because we need to handle doc comments
+ // (where we take as many doc comment attributes as possible) and possibly
+ // merging derives into a single attribute.
+ loop {
+ if attrs.is_empty() {
+ return Some(result);
+ }
+
+ // Handle doc comments.
+ let (doc_comment_len, doc_comment_str) =
+ rewrite_initial_doc_comments(context, attrs, shape)?;
+ if doc_comment_len > 0 {
+ let doc_comment_str = doc_comment_str.expect("doc comments, but no result");
+ result.push_str(&doc_comment_str);
+
+ let missing_span = attrs
+ .get(doc_comment_len)
+ .map(|next| mk_sp(attrs[doc_comment_len - 1].span.hi(), next.span.lo()));
+ if let Some(missing_span) = missing_span {
+ let snippet = context.snippet(missing_span);
+ let (mla, mlb) = has_newlines_before_after_comment(snippet);
+ let comment = crate::comment::recover_missing_comment_in_span(
+ missing_span,
+ shape.with_max_width(context.config),
+ context,
+ 0,
+ )?;
+ let comment = if comment.is_empty() {
+ format!("\n{}", mlb)
+ } else {
+ format!("{}{}\n{}", mla, comment, mlb)
+ };
+ result.push_str(&comment);
+ result.push_str(&shape.indent.to_string(context.config));
+ }
+
+ attrs = &attrs[doc_comment_len..];
+
+ continue;
+ }
+
+ // Handle derives if we will merge them.
+ if context.config.merge_derives() && is_derive(&attrs[0]) {
+ let derives = take_while_with_pred(context, attrs, is_derive);
+ let derive_str = format_derive(derives, shape, context)?;
+ result.push_str(&derive_str);
+
+ let missing_span = attrs
+ .get(derives.len())
+ .map(|next| mk_sp(attrs[derives.len() - 1].span.hi(), next.span.lo()));
+ if let Some(missing_span) = missing_span {
+ let comment = crate::comment::recover_missing_comment_in_span(
+ missing_span,
+ shape.with_max_width(context.config),
+ context,
+ 0,
+ )?;
+ result.push_str(&comment);
+ if let Some(next) = attrs.get(derives.len()) {
+ if next.is_doc_comment() {
+ let snippet = context.snippet(missing_span);
+ let (_, mlb) = has_newlines_before_after_comment(snippet);
+ result.push_str(&mlb);
+ }
+ }
+ result.push('\n');
+ result.push_str(&shape.indent.to_string(context.config));
+ }
+
+ attrs = &attrs[derives.len()..];
+
+ continue;
+ }
+
+ // If we get here, then we have a regular attribute, just handle one
+ // at a time.
+
+ let formatted_attr = attrs[0].rewrite(context, shape)?;
+ result.push_str(&formatted_attr);
+
+ let missing_span = attrs
+ .get(1)
+ .map(|next| mk_sp(attrs[0].span.hi(), next.span.lo()));
+ if let Some(missing_span) = missing_span {
+ let comment = crate::comment::recover_missing_comment_in_span(
+ missing_span,
+ shape.with_max_width(context.config),
+ context,
+ 0,
+ )?;
+ result.push_str(&comment);
+ if let Some(next) = attrs.get(1) {
+ if next.is_doc_comment() {
+ let snippet = context.snippet(missing_span);
+ let (_, mlb) = has_newlines_before_after_comment(snippet);
+ result.push_str(&mlb);
+ }
+ }
+ result.push('\n');
+ result.push_str(&shape.indent.to_string(context.config));
+ }
+
+ attrs = &attrs[1..];
+ }
+ }
+}
+
+fn attr_prefix(attr: &ast::Attribute) -> &'static str {
+ match attr.style {
+ ast::AttrStyle::Inner => "#!",
+ ast::AttrStyle::Outer => "#",
+ }
+}
+
+pub(crate) trait MetaVisitor<'ast> {
+ fn visit_meta_item(&mut self, meta_item: &'ast ast::MetaItem) {
+ match meta_item.kind {
+ ast::MetaItemKind::Word => self.visit_meta_word(meta_item),
+ ast::MetaItemKind::List(ref list) => self.visit_meta_list(meta_item, list),
+ ast::MetaItemKind::NameValue(ref lit) => self.visit_meta_name_value(meta_item, lit),
+ }
+ }
+
+ fn visit_meta_list(
+ &mut self,
+ _meta_item: &'ast ast::MetaItem,
+ list: &'ast [ast::NestedMetaItem],
+ ) {
+ for nm in list {
+ self.visit_nested_meta_item(nm);
+ }
+ }
+
+ fn visit_meta_word(&mut self, _meta_item: &'ast ast::MetaItem) {}
+
+ fn visit_meta_name_value(&mut self, _meta_item: &'ast ast::MetaItem, _lit: &'ast ast::Lit) {}
+
+ fn visit_nested_meta_item(&mut self, nm: &'ast ast::NestedMetaItem) {
+ match nm {
+ ast::NestedMetaItem::MetaItem(ref meta_item) => self.visit_meta_item(meta_item),
+ ast::NestedMetaItem::Literal(ref lit) => self.visit_literal(lit),
+ }
+ }
+
+ fn visit_literal(&mut self, _lit: &'ast ast::Lit) {}
+}
projects / rustc.git / blobdiff