771 lines
27 KiB
Rust
771 lines
27 KiB
Rust
// Copyright 2015 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 list-like expressions and items.
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use std::cmp;
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use std::iter::Peekable;
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use config::lists::*;
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use syntax::codemap::BytePos;
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use comment::{find_comment_end, rewrite_comment, FindUncommented};
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use config::{Config, IndentStyle};
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use rewrite::RewriteContext;
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use shape::{Indent, Shape};
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use utils::{count_newlines, first_line_width, last_line_width, mk_sp, starts_with_newline};
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use visitor::SnippetProvider;
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pub struct ListFormatting<'a> {
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pub tactic: DefinitiveListTactic,
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pub separator: &'a str,
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pub trailing_separator: SeparatorTactic,
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pub separator_place: SeparatorPlace,
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pub shape: Shape,
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// Non-expressions, e.g. items, will have a new line at the end of the list.
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// Important for comment styles.
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pub ends_with_newline: bool,
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// Remove newlines between list elements for expressions.
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pub preserve_newline: bool,
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pub config: &'a Config,
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}
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impl<'a> ListFormatting<'a> {
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pub fn needs_trailing_separator(&self) -> bool {
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match self.trailing_separator {
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// We always put separator in front.
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SeparatorTactic::Always => true,
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SeparatorTactic::Vertical => self.tactic == DefinitiveListTactic::Vertical,
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SeparatorTactic::Never => {
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self.tactic == DefinitiveListTactic::Vertical && self.separator_place.is_front()
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}
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}
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}
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}
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impl AsRef<ListItem> for ListItem {
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fn as_ref(&self) -> &ListItem {
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self
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}
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}
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#[derive(PartialEq, Eq)]
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pub enum ListItemCommentStyle {
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// Try to keep the comment on the same line with the item.
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SameLine,
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// Put the comment on the previous or the next line of the item.
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DifferentLine,
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// No comment available.
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None,
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}
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pub struct ListItem {
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// None for comments mean that they are not present.
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pub pre_comment: Option<String>,
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pub pre_comment_style: ListItemCommentStyle,
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// Item should include attributes and doc comments. None indicates a failed
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// rewrite.
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pub item: Option<String>,
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pub post_comment: Option<String>,
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// Whether there is extra whitespace before this item.
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pub new_lines: bool,
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}
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impl ListItem {
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pub fn inner_as_ref(&self) -> &str {
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self.item.as_ref().map_or("", |s| s)
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}
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pub fn is_different_group(&self) -> bool {
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self.inner_as_ref().contains('\n') || self.pre_comment.is_some()
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|| self.post_comment
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.as_ref()
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.map_or(false, |s| s.contains('\n'))
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}
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pub fn is_multiline(&self) -> bool {
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self.inner_as_ref().contains('\n')
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|| self.pre_comment
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.as_ref()
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.map_or(false, |s| s.contains('\n'))
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|| self.post_comment
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.as_ref()
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.map_or(false, |s| s.contains('\n'))
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}
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pub fn has_comment(&self) -> bool {
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self.pre_comment
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.as_ref()
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.map_or(false, |comment| comment.trim_left().starts_with("//"))
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|| self.post_comment
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.as_ref()
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.map_or(false, |comment| comment.trim_left().starts_with("//"))
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}
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pub fn from_str<S: Into<String>>(s: S) -> ListItem {
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ListItem {
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pre_comment: None,
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pre_comment_style: ListItemCommentStyle::None,
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item: Some(s.into()),
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post_comment: None,
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new_lines: false,
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}
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}
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}
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/// The type of separator for lists.
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#[derive(Copy, Clone, Eq, PartialEq, Debug)]
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pub enum Separator {
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Comma,
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VerticalBar,
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}
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impl Separator {
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pub fn len(&self) -> usize {
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match *self {
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// 2 = `, `
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Separator::Comma => 2,
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// 3 = ` | `
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Separator::VerticalBar => 3,
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}
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}
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}
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pub fn definitive_tactic<I, T>(
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items: I,
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tactic: ListTactic,
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sep: Separator,
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width: usize,
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) -> DefinitiveListTactic
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where
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I: IntoIterator<Item = T> + Clone,
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T: AsRef<ListItem>,
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{
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let pre_line_comments = items
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.clone()
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.into_iter()
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.any(|item| item.as_ref().has_comment());
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let limit = match tactic {
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_ if pre_line_comments => return DefinitiveListTactic::Vertical,
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ListTactic::Mixed => return DefinitiveListTactic::Mixed,
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ListTactic::Horizontal => return DefinitiveListTactic::Horizontal,
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ListTactic::Vertical => return DefinitiveListTactic::Vertical,
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ListTactic::LimitedHorizontalVertical(limit) => ::std::cmp::min(width, limit),
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ListTactic::HorizontalVertical => width,
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};
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let (sep_count, total_width) = calculate_width(items.clone());
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let total_sep_len = sep.len() * sep_count.checked_sub(1).unwrap_or(0);
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let real_total = total_width + total_sep_len;
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if real_total <= limit && !pre_line_comments
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&& !items.into_iter().any(|item| item.as_ref().is_multiline())
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{
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DefinitiveListTactic::Horizontal
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} else {
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DefinitiveListTactic::Vertical
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}
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}
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// Format a list of commented items into a string.
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// TODO: add unit tests
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pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
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where
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I: IntoIterator<Item = T> + Clone,
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T: AsRef<ListItem>,
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{
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let tactic = formatting.tactic;
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let sep_len = formatting.separator.len();
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// Now that we know how we will layout, we can decide for sure if there
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// will be a trailing separator.
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let mut trailing_separator = formatting.needs_trailing_separator();
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let mut result = String::with_capacity(128);
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let cloned_items = items.clone();
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let mut iter = items.into_iter().enumerate().peekable();
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let mut item_max_width: Option<usize> = None;
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let sep_place =
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SeparatorPlace::from_tactic(formatting.separator_place, tactic, formatting.separator);
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let mut line_len = 0;
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let indent_str = &formatting.shape.indent.to_string(formatting.config);
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while let Some((i, item)) = iter.next() {
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let item = item.as_ref();
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let inner_item = item.item.as_ref()?;
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let first = i == 0;
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let last = iter.peek().is_none();
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let mut separate = match sep_place {
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SeparatorPlace::Front => !first,
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SeparatorPlace::Back => !last || trailing_separator,
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};
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let item_sep_len = if separate { sep_len } else { 0 };
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// Item string may be multi-line. Its length (used for block comment alignment)
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// should be only the length of the last line.
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let item_last_line = if item.is_multiline() {
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inner_item.lines().last().unwrap_or("")
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} else {
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inner_item.as_ref()
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};
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let mut item_last_line_width = item_last_line.len() + item_sep_len;
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if item_last_line.starts_with(&**indent_str) {
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item_last_line_width -= indent_str.len();
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}
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match tactic {
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DefinitiveListTactic::Horizontal if !first => {
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result.push(' ');
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}
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DefinitiveListTactic::SpecialMacro(num_args_before) => {
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if i == 0 {
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// Nothing
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} else if i < num_args_before {
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result.push(' ');
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} else if i <= num_args_before + 1 {
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result.push('\n');
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result.push_str(indent_str);
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} else {
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result.push(' ');
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}
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}
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DefinitiveListTactic::Vertical if !first => {
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result.push('\n');
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result.push_str(indent_str);
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}
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DefinitiveListTactic::Mixed => {
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let total_width = total_item_width(item) + item_sep_len;
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// 1 is space between separator and item.
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if line_len > 0 && line_len + 1 + total_width > formatting.shape.width {
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result.push('\n');
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result.push_str(indent_str);
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line_len = 0;
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if formatting.ends_with_newline {
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if last {
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separate = true;
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} else {
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trailing_separator = true;
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}
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}
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}
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if line_len > 0 {
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result.push(' ');
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line_len += 1;
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}
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line_len += total_width;
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}
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_ => {}
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}
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// Pre-comments
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if let Some(ref comment) = item.pre_comment {
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// Block style in non-vertical mode.
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let block_mode = tactic != DefinitiveListTactic::Vertical;
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// Width restriction is only relevant in vertical mode.
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let comment =
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rewrite_comment(comment, block_mode, formatting.shape, formatting.config)?;
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result.push_str(&comment);
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if tactic == DefinitiveListTactic::Vertical {
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// We cannot keep pre-comments on the same line if the comment if normalized.
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let keep_comment = if formatting.config.normalize_comments()
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|| item.pre_comment_style == ListItemCommentStyle::DifferentLine
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{
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false
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} else {
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// We will try to keep the comment on the same line with the item here.
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// 1 = ` `
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let total_width = total_item_width(item) + item_sep_len + 1;
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total_width <= formatting.shape.width
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};
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if keep_comment {
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result.push(' ');
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} else {
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result.push('\n');
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result.push_str(indent_str);
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}
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} else {
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result.push(' ');
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}
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item_max_width = None;
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}
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if separate && sep_place.is_front() && !first {
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result.push_str(formatting.separator.trim());
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result.push(' ');
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}
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result.push_str(&inner_item[..]);
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// Post-comments
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if tactic != DefinitiveListTactic::Vertical && item.post_comment.is_some() {
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let comment = item.post_comment.as_ref().unwrap();
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let formatted_comment = rewrite_comment(
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comment,
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true,
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Shape::legacy(formatting.shape.width, Indent::empty()),
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formatting.config,
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)?;
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result.push(' ');
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result.push_str(&formatted_comment);
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}
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if separate && sep_place.is_back() {
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result.push_str(formatting.separator);
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}
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if tactic == DefinitiveListTactic::Vertical && item.post_comment.is_some() {
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let comment = item.post_comment.as_ref().unwrap();
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let overhead = last_line_width(&result) + first_line_width(comment.trim());
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let rewrite_post_comment = |item_max_width: &mut Option<usize>| {
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if item_max_width.is_none() && !last && !inner_item.contains('\n') {
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*item_max_width = Some(max_width_of_item_with_post_comment(
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&cloned_items,
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i,
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overhead,
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formatting.config.max_width(),
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));
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}
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let overhead = if starts_with_newline(comment) {
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0
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} else if let Some(max_width) = *item_max_width {
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max_width + 2
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} else {
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// 1 = space between item and comment.
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item_last_line_width + 1
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};
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let width = formatting.shape.width.checked_sub(overhead).unwrap_or(1);
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let offset = formatting.shape.indent + overhead;
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let comment_shape = Shape::legacy(width, offset);
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// Use block-style only for the last item or multiline comments.
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let block_style = !formatting.ends_with_newline && last
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|| comment.trim().contains('\n')
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|| comment.trim().len() > width;
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rewrite_comment(
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comment.trim_left(),
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block_style,
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comment_shape,
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formatting.config,
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)
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};
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let mut formatted_comment = rewrite_post_comment(&mut item_max_width)?;
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if !starts_with_newline(comment) {
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let mut comment_alignment =
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post_comment_alignment(item_max_width, inner_item.len());
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if first_line_width(&formatted_comment) + last_line_width(&result)
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+ comment_alignment + 1 > formatting.config.max_width()
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{
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item_max_width = None;
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formatted_comment = rewrite_post_comment(&mut item_max_width)?;
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comment_alignment = post_comment_alignment(item_max_width, inner_item.len());
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}
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for _ in 0..(comment_alignment + 1) {
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result.push(' ');
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}
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// An additional space for the missing trailing separator.
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if last && item_max_width.is_some() && !separate && !formatting.separator.is_empty()
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{
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result.push(' ');
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}
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} else {
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result.push('\n');
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result.push_str(indent_str);
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}
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if formatted_comment.contains('\n') {
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item_max_width = None;
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}
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result.push_str(&formatted_comment);
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} else {
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item_max_width = None;
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}
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if formatting.preserve_newline && !last && tactic == DefinitiveListTactic::Vertical
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&& item.new_lines
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{
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item_max_width = None;
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result.push('\n');
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}
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}
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Some(result)
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}
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fn max_width_of_item_with_post_comment<I, T>(
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items: &I,
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i: usize,
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overhead: usize,
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max_budget: usize,
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) -> usize
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where
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I: IntoIterator<Item = T> + Clone,
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T: AsRef<ListItem>,
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{
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let mut max_width = 0;
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let mut first = true;
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for item in items.clone().into_iter().skip(i) {
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let item = item.as_ref();
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let inner_item_width = item.inner_as_ref().len();
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if !first
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&& (item.is_different_group() || !item.post_comment.is_some()
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|| inner_item_width + overhead > max_budget)
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{
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return max_width;
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}
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if max_width < inner_item_width {
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max_width = inner_item_width;
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}
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if item.new_lines {
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return max_width;
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}
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first = false;
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}
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max_width
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}
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fn post_comment_alignment(item_max_width: Option<usize>, inner_item_len: usize) -> usize {
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item_max_width
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.and_then(|max_line_width| max_line_width.checked_sub(inner_item_len))
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.unwrap_or(0)
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}
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pub struct ListItems<'a, I, F1, F2, F3>
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where
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I: Iterator,
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{
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snippet_provider: &'a SnippetProvider<'a>,
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inner: Peekable<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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prev_span_end: BytePos,
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next_span_start: BytePos,
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terminator: &'a str,
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separator: &'a str,
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leave_last: bool,
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}
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impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
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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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type Item = ListItem;
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fn next(&mut self) -> Option<Self::Item> {
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let white_space: &[_] = &[' ', '\t'];
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self.inner.next().map(|item| {
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let mut new_lines = false;
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// Pre-comment
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let pre_snippet = self.snippet_provider
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.span_to_snippet(mk_sp(self.prev_span_end, (self.get_lo)(&item)))
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.unwrap();
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let trimmed_pre_snippet = pre_snippet.trim();
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let has_single_line_comment = trimmed_pre_snippet.starts_with("//");
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let has_block_comment = trimmed_pre_snippet.starts_with("/*");
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let (pre_comment, pre_comment_style) = if has_single_line_comment {
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(
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Some(trimmed_pre_snippet.to_owned()),
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ListItemCommentStyle::DifferentLine,
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)
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} else if has_block_comment {
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let comment_end = pre_snippet.chars().rev().position(|c| c == '/').unwrap();
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if pre_snippet
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.chars()
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.rev()
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.take(comment_end + 1)
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.any(|c| c == '\n')
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{
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(
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Some(trimmed_pre_snippet.to_owned()),
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ListItemCommentStyle::DifferentLine,
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)
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} else {
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(
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Some(trimmed_pre_snippet.to_owned()),
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ListItemCommentStyle::SameLine,
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)
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}
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} else {
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(None, ListItemCommentStyle::None)
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};
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|
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// Post-comment
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let next_start = match self.inner.peek() {
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Some(next_item) => (self.get_lo)(next_item),
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None => self.next_span_start,
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};
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let post_snippet = self.snippet_provider
|
|
.span_to_snippet(mk_sp((self.get_hi)(&item), next_start))
|
|
.unwrap();
|
|
|
|
let comment_end = match self.inner.peek() {
|
|
Some(..) => {
|
|
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 i > 0 && &post_snippet[i - 1..i] == "/" => block_open_index = None,
|
|
_ => (),
|
|
}
|
|
}
|
|
let newline_index = post_snippet.find('\n');
|
|
if let Some(separator_index) = post_snippet.find_uncommented(self.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
|
|
}
|
|
}
|
|
None => post_snippet
|
|
.find_uncommented(self.terminator)
|
|
.unwrap_or_else(|| post_snippet.len()),
|
|
};
|
|
|
|
if !post_snippet.is_empty() && comment_end > 0 {
|
|
// Account for extra whitespace between items. This is fiddly
|
|
// because of the way we divide pre- and post- comments.
|
|
|
|
// Everything from the separator to the next item.
|
|
let test_snippet = &post_snippet[comment_end - 1..];
|
|
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];
|
|
|
|
if count_newlines(test_snippet) > 1 {
|
|
// There were multiple line breaks which got trimmed to nothing.
|
|
new_lines = true;
|
|
}
|
|
}
|
|
|
|
// Cleanup post-comment: strip separators and whitespace.
|
|
self.prev_span_end = (self.get_hi)(&item) + BytePos(comment_end as u32);
|
|
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.ends_with(',') {
|
|
post_snippet[..(post_snippet.len() - 1)].trim_matches(white_space)
|
|
} else {
|
|
post_snippet
|
|
};
|
|
|
|
let post_comment = if !post_snippet_trimmed.is_empty() {
|
|
Some(post_snippet_trimmed.to_owned())
|
|
} else {
|
|
None
|
|
};
|
|
|
|
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,
|
|
}
|
|
})
|
|
}
|
|
}
|
|
|
|
#[cfg_attr(feature = "cargo-clippy", allow(too_many_arguments))]
|
|
// Creates an iterator over a list's items with associated comments.
|
|
pub 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 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, |str| str.len())
|
|
}
|
|
|
|
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 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 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 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 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,
|
|
config: context.config,
|
|
}
|
|
}
|