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