465 lines
16 KiB
Rust
465 lines
16 KiB
Rust
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Format attributes and meta items.
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use comment::{contains_comment, rewrite_doc_comment};
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use config::lists::*;
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use config::IndentStyle;
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use expr::rewrite_literal;
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use lists::{itemize_list, write_list, ListFormatting};
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use rewrite::{Rewrite, RewriteContext};
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use shape::Shape;
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use types::{rewrite_path, PathContext};
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use utils::{count_newlines, mk_sp};
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use std::borrow::Cow;
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use syntax::ast;
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use syntax::codemap::{BytePos, Span, DUMMY_SP};
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/// Returns attributes on the given statement.
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pub fn get_attrs_from_stmt(stmt: &ast::Stmt) -> &[ast::Attribute] {
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match stmt.node {
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ast::StmtKind::Local(ref local) => &local.attrs,
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ast::StmtKind::Item(ref item) => &item.attrs,
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ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => &expr.attrs,
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ast::StmtKind::Mac(ref mac) => &mac.2,
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}
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}
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/// Returns attributes that are within `outer_span`.
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pub fn filter_inline_attrs(attrs: &[ast::Attribute], outer_span: Span) -> 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.check_name("derive")
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}
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/// Returns the arguments of `#[derive(...)]`.
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fn get_derive_spans<'a>(attr: &ast::Attribute) -> Option<Vec<Span>> {
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attr.meta_item_list().map(|meta_item_list| {
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meta_item_list
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.iter()
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.map(|nested_meta_item| nested_meta_item.span)
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.collect()
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})
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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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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 => 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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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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derive_args: &[Span],
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prefix: &str,
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shape: Shape,
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context: &RewriteContext,
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) -> Option<String> {
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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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let argument_shape = argument_shape(10 + prefix.len(), 2, shape, context)?;
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let item_str = format_arg_list(
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derive_args.iter(),
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|_| DUMMY_SP.lo(),
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|_| DUMMY_SP.hi(),
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|sp| Some(context.snippet(**sp).to_owned()),
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DUMMY_SP,
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context,
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argument_shape,
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// 10 = "[derive()]", 3 = "()" and "]"
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shape.offset_left(10 + prefix.len())?.sub_width(3)?,
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None,
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)?;
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result.push_str(&item_str);
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if item_str.starts_with('\n') {
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result.push(',');
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result.push_str(&shape.indent.to_string_with_newline(context.config));
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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_sugared_doc);
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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.node {
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ast::NestedMetaItemKind::MetaItem(ref meta_item) => meta_item.rewrite(context, shape),
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ast::NestedMetaItemKind::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.node {
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ast::MetaItemKind::Word => {
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rewrite_path(context, PathContext::Type, None, &self.ident, 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.ident, shape)?;
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let snippet = context.snippet(self.span);
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// 2 = )] (this might go wrong if there is whitespace between the brackets, but
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// it's close enough).
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let snippet = snippet[..snippet.len() - 2].trim();
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let trailing_comma = if snippet.ends_with(',') { "," } else { "" };
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let argument_shape =
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argument_shape(path.len() + 1, 2 + trailing_comma.len(), shape, context)?;
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let item_str = format_arg_list(
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list.iter(),
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|nested_meta_item| nested_meta_item.span.lo(),
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|nested_meta_item| nested_meta_item.span.hi(),
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|nested_meta_item| nested_meta_item.rewrite(context, argument_shape),
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self.span,
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context,
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argument_shape,
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// 3 = "()" and "]"
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shape
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.offset_left(path.len())?
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.sub_width(3 + trailing_comma.len())?,
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Some(context.config.width_heuristics().fn_call_width),
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)?;
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let indent = if item_str.starts_with('\n') {
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shape.indent.to_string_with_newline(context.config)
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} else {
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Cow::Borrowed("")
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};
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format!("{}({}{}{})", path, item_str, trailing_comma, indent)
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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.ident, 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 contiue 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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fn format_arg_list<I, T, F1, F2, F3>(
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list: I,
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get_lo: F1,
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get_hi: F2,
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get_item_string: F3,
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span: Span,
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context: &RewriteContext,
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shape: Shape,
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one_line_shape: Shape,
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one_line_limit: Option<usize>,
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) -> Option<String>
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where
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I: Iterator<Item = T>,
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F1: Fn(&T) -> BytePos,
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F2: Fn(&T) -> BytePos,
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F3: Fn(&T) -> Option<String>,
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{
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let items = itemize_list(
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context.snippet_provider,
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list,
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")",
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",",
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get_lo,
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get_hi,
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get_item_string,
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span.lo(),
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span.hi(),
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false,
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);
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let item_vec = items.collect::<Vec<_>>();
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let tactic = if let Some(limit) = one_line_limit {
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ListTactic::LimitedHorizontalVertical(limit)
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} else {
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ListTactic::HorizontalVertical
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};
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let tactic =
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::lists::definitive_tactic(&item_vec, tactic, ::lists::Separator::Comma, shape.width);
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let fmt = ListFormatting::new(shape, context.config)
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.tactic(tactic)
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.ends_with_newline(false);
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let item_str = write_list(&item_vec, &fmt)?;
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let one_line_budget = one_line_shape.width;
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if context.config.indent_style() == IndentStyle::Visual
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|| (!item_str.contains('\n') && item_str.len() <= one_line_budget)
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{
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Some(item_str)
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} else {
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let nested_indent = shape.indent.to_string_with_newline(context.config);
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Some(format!("{}{}", nested_indent, item_str))
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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_sugared_doc {
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rewrite_doc_comment(snippet, shape.comment(context.config), context.config)
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} else {
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let prefix = attr_prefix(self);
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if contains_comment(snippet) {
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return Some(snippet.to_owned());
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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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self.meta()
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.and_then(|meta| 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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}
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}
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}
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impl<'a> 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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// 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 = ::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 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 mut derive_spans = vec![];
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for derive in derives {
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derive_spans.append(&mut get_derive_spans(derive)?);
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}
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let derive_str =
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format_derive(&derive_spans, attr_prefix(&attrs[0]), 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 = ::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_sugared_doc {
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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 = ::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_sugared_doc {
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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 => "#!",
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ast::AttrStyle::Outer => "#",
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}
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}
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