1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Format with vertical alignment.
16 use syntax::codemap::{BytePos, Span};
19 use codemap::SpanUtils;
20 use comment::{combine_strs_with_missing_comments, contains_comment};
21 use expr::rewrite_field;
22 use items::{rewrite_struct_field, rewrite_struct_field_prefix};
23 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListTactic, Separator,
25 use rewrite::{Rewrite, RewriteContext};
26 use shape::{Indent, Shape};
27 use utils::{contains_skip, is_attributes_extendable, mk_sp};
29 pub trait AlignedItem {
30 fn skip(&self) -> bool;
31 fn get_span(&self) -> Span;
32 fn rewrite_prefix(&self, context: &RewriteContext, shape: Shape) -> Option<String>;
33 fn rewrite_aligned_item(
35 context: &RewriteContext,
37 prefix_max_width: usize,
41 impl AlignedItem for ast::StructField {
42 fn skip(&self) -> bool {
43 contains_skip(&self.attrs)
46 fn get_span(&self) -> Span {
50 fn rewrite_prefix(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
51 let attrs_str = self.attrs.rewrite(context, shape)?;
52 let missing_span = if self.attrs.is_empty() {
53 mk_sp(self.span.lo(), self.span.lo())
55 mk_sp(self.attrs.last().unwrap().span.hi(), self.span.lo())
57 let attrs_extendable = context.config.attributes_on_same_line_as_field()
58 && is_attributes_extendable(&attrs_str);
59 rewrite_struct_field_prefix(context, self).and_then(|field_str| {
60 combine_strs_with_missing_comments(
71 fn rewrite_aligned_item(
73 context: &RewriteContext,
75 prefix_max_width: usize,
77 rewrite_struct_field(context, self, shape, prefix_max_width)
81 impl AlignedItem for ast::Field {
82 fn skip(&self) -> bool {
83 contains_skip(&self.attrs)
86 fn get_span(&self) -> Span {
90 fn rewrite_prefix(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
91 let attrs_str = self.attrs.rewrite(context, shape)?;
92 let name = &self.ident.node.to_string();
93 let missing_span = if self.attrs.is_empty() {
94 mk_sp(self.span.lo(), self.span.lo())
96 mk_sp(self.attrs.last().unwrap().span.hi(), self.span.lo())
98 combine_strs_with_missing_comments(
104 is_attributes_extendable(&attrs_str),
108 fn rewrite_aligned_item(
110 context: &RewriteContext,
112 prefix_max_width: usize,
113 ) -> Option<String> {
114 rewrite_field(context, self, shape, prefix_max_width)
118 pub fn rewrite_with_alignment<T: AlignedItem>(
120 context: &RewriteContext,
123 one_line_width: usize,
124 ) -> Option<String> {
125 let (spaces, group_index) = if context.config.struct_field_align_threshold() > 0 {
126 group_aligned_items(context, fields)
128 ("", fields.len() - 1)
130 let init = &fields[0..group_index + 1];
131 let rest = &fields[group_index + 1..];
132 let init_last_pos = if rest.is_empty() {
135 // Decide whether the missing comments should stick to init or rest.
136 let init_hi = init[init.len() - 1].get_span().hi();
137 let rest_lo = rest[0].get_span().lo();
138 let missing_span = mk_sp(init_hi, rest_lo);
139 let missing_span = mk_sp(
140 context.codemap.span_after(missing_span, ","),
144 let snippet = context.snippet(missing_span);
145 if snippet.trim_left().starts_with("//") {
146 let offset = snippet.lines().next().map_or(0, |l| l.len());
148 init_hi + BytePos(offset as u32 + 2)
149 } else if snippet.trim_left().starts_with("/*") {
150 let comment_lines = snippet
152 .position(|line| line.trim_right().ends_with("*/"))
157 .take(comment_lines + 1)
162 init_hi + BytePos(offset as u32 + 2)
167 let init_span = mk_sp(span.lo(), init_last_pos);
168 let one_line_width = if rest.is_empty() { one_line_width } else { 0 };
170 rewrite_aligned_items_inner(context, init, init_span, shape.indent, one_line_width)?;
172 Some(result + spaces)
174 let rest_span = mk_sp(init_last_pos, span.hi());
175 let rest_str = rewrite_with_alignment(rest, context, shape, rest_span, one_line_width)?;
177 result + spaces + "\n"
180 .block_indent(context.config)
181 .to_string(context.config) + &rest_str,
186 fn struct_field_preix_max_min_width<T: AlignedItem>(
187 context: &RewriteContext,
190 ) -> (usize, usize) {
195 .rewrite_prefix(context, shape)
196 .and_then(|field_str| if field_str.contains('\n') {
199 Some(field_str.len())
202 .fold(Some((0, ::std::usize::MAX)), |acc, len| match (acc, len) {
203 (Some((max_len, min_len)), Some(len)) => {
204 Some((cmp::max(max_len, len), cmp::min(min_len, len)))
211 fn rewrite_aligned_items_inner<T: AlignedItem>(
212 context: &RewriteContext,
216 one_line_width: usize,
217 ) -> Option<String> {
218 let item_indent = offset.block_indent(context.config);
220 let item_shape = Shape::indented(item_indent, context.config).sub_width(1)?;
221 let (mut field_prefix_max_width, field_prefix_min_width) =
222 struct_field_preix_max_min_width(context, fields, item_shape);
223 let max_diff = field_prefix_max_width
224 .checked_sub(field_prefix_min_width)
226 if max_diff > context.config.struct_field_align_threshold() {
227 field_prefix_max_width = 0;
230 let items = itemize_list(
234 |field| field.get_span().lo(),
235 |field| field.get_span().hi(),
236 |field| field.rewrite_aligned_item(context, item_shape, field_prefix_max_width),
240 ).collect::<Vec<_>>();
242 let tactic = definitive_tactic(
244 ListTactic::HorizontalVertical,
249 let fmt = ListFormatting {
252 trailing_separator: context.config.trailing_comma(),
253 separator_place: SeparatorPlace::Back,
255 ends_with_newline: true,
256 preserve_newline: true,
257 config: context.config,
259 write_list(&items, &fmt)
262 fn group_aligned_items<T: AlignedItem>(
263 context: &RewriteContext,
265 ) -> (&'static str, usize) {
267 for i in 0..fields.len() - 1 {
268 if fields[i].skip() {
271 // See if there are comments or empty lines between fields.
272 let span = mk_sp(fields[i].get_span().hi(), fields[i + 1].get_span().lo());
273 let snippet = context
279 let spacings = if snippet.lines().rev().skip(1).any(|l| l.trim().is_empty()) {
284 if contains_comment(&snippet) || snippet.lines().count() > 1 {
285 return (spacings, index);