1 // Copyright 2015 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.
12 use std::iter::Peekable;
14 use syntax::codemap::{self, CodeMap, BytePos};
17 use comment::{FindUncommented, rewrite_comment, find_comment_end};
18 use config::{Config, IndentStyle};
19 use rewrite::RewriteContext;
21 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
22 /// Formatting tactic for lists. This will be cast down to a
23 /// DefinitiveListTactic depending on the number and length of the items and
28 // All items on one row.
30 // Try Horizontal layout, if that fails then vertical.
32 // HorizontalVertical with a soft limit of n characters.
33 LimitedHorizontalVertical(usize),
34 // Pack as many items as possible per row over (possibly) many rows.
38 impl_enum_serialize_and_deserialize!(ListTactic, Vertical, Horizontal, HorizontalVertical, Mixed);
40 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
41 pub enum SeparatorTactic {
47 impl_enum_serialize_and_deserialize!(SeparatorTactic, Always, Never, Vertical);
49 impl SeparatorTactic {
50 pub fn from_bool(b: bool) -> SeparatorTactic {
52 SeparatorTactic::Always
54 SeparatorTactic::Never
59 pub struct ListFormatting<'a> {
60 pub tactic: DefinitiveListTactic,
61 pub separator: &'a str,
62 pub trailing_separator: SeparatorTactic,
64 // Non-expressions, e.g. items, will have a new line at the end of the list.
65 // Important for comment styles.
66 pub ends_with_newline: bool,
67 pub config: &'a Config,
70 pub fn format_fn_args<I>(items: I, shape: Shape, config: &Config) -> Option<String>
71 where I: Iterator<Item = ListItem>
76 ListTactic::LimitedHorizontalVertical(config.fn_call_width()))
79 pub fn format_item_list<I>(items: I, shape: Shape, config: &Config) -> Option<String>
80 where I: Iterator<Item = ListItem>
82 list_helper(items, shape, config, ListTactic::HorizontalVertical)
85 pub fn list_helper<I>(items: I, shape: Shape, config: &Config, tactic: ListTactic) -> Option<String>
86 where I: Iterator<Item = ListItem>
88 let item_vec: Vec<_> = items.collect();
89 let tactic = definitive_tactic(&item_vec, tactic, shape.width);
90 let fmt = ListFormatting {
93 trailing_separator: SeparatorTactic::Never,
95 ends_with_newline: false,
99 write_list(&item_vec, &fmt)
102 impl AsRef<ListItem> for ListItem {
103 fn as_ref(&self) -> &ListItem {
108 pub struct ListItem {
109 // None for comments mean that they are not present.
110 pub pre_comment: Option<String>,
111 // Item should include attributes and doc comments. None indicates a failed
113 pub item: Option<String>,
114 pub post_comment: Option<String>,
115 // Whether there is extra whitespace before this item.
120 pub fn is_multiline(&self) -> bool {
121 self.item.as_ref().map_or(false, |s| s.contains('\n')) || self.pre_comment.is_some() ||
124 .map_or(false, |s| s.contains('\n'))
127 pub fn has_line_pre_comment(&self) -> bool {
130 .map_or(false, |comment| comment.starts_with("//"))
133 pub fn from_str<S: Into<String>>(s: S) -> ListItem {
136 item: Some(s.into()),
143 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
144 /// The definitive formatting tactic for lists.
145 pub enum DefinitiveListTactic {
151 pub fn definitive_tactic<I, T>(items: I, tactic: ListTactic, width: usize) -> DefinitiveListTactic
152 where I: IntoIterator<Item = T> + Clone,
155 let pre_line_comments = items
158 .any(|item| item.as_ref().has_line_pre_comment());
160 let limit = match tactic {
161 _ if pre_line_comments => return DefinitiveListTactic::Vertical,
162 ListTactic::Mixed => return DefinitiveListTactic::Mixed,
163 ListTactic::Horizontal => return DefinitiveListTactic::Horizontal,
164 ListTactic::Vertical => return DefinitiveListTactic::Vertical,
165 ListTactic::LimitedHorizontalVertical(limit) => ::std::cmp::min(width, limit),
166 ListTactic::HorizontalVertical => width,
169 let (sep_count, total_width) = calculate_width(items.clone());
170 let sep_len = ", ".len(); // FIXME: make more generic?
171 let total_sep_len = sep_len * sep_count.checked_sub(1).unwrap_or(0);
172 let real_total = total_width + total_sep_len;
174 if real_total <= limit && !pre_line_comments &&
175 !items.into_iter().any(|item| item.as_ref().is_multiline()) {
176 DefinitiveListTactic::Horizontal
178 DefinitiveListTactic::Vertical
182 // Format a list of commented items into a string.
183 // TODO: add unit tests
184 pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
185 where I: IntoIterator<Item = T>,
188 let tactic = formatting.tactic;
189 let sep_len = formatting.separator.len();
191 // Now that we know how we will layout, we can decide for sure if there
192 // will be a trailing separator.
193 let trailing_separator = needs_trailing_separator(formatting.trailing_separator, tactic);
194 let mut result = String::new();
195 let mut iter = items.into_iter().enumerate().peekable();
197 let mut line_len = 0;
198 let indent_str = &formatting.shape.indent.to_string(formatting.config);
199 while let Some((i, item)) = iter.next() {
200 let item = item.as_ref();
201 let inner_item = try_opt!(item.item.as_ref());
203 let last = iter.peek().is_none();
204 let separate = !last || trailing_separator;
205 let item_sep_len = if separate { sep_len } else { 0 };
207 // Item string may be multi-line. Its length (used for block comment alignment)
208 // should be only the length of the last line.
209 let item_last_line = if item.is_multiline() {
210 inner_item.lines().last().unwrap_or("")
214 let mut item_last_line_width = item_last_line.len() + item_sep_len;
215 if item_last_line.starts_with(indent_str) {
216 item_last_line_width -= indent_str.len();
220 DefinitiveListTactic::Horizontal if !first => {
223 DefinitiveListTactic::Vertical if !first => {
225 result.push_str(indent_str);
227 DefinitiveListTactic::Mixed => {
228 let total_width = total_item_width(item) + item_sep_len;
230 // 1 is space between separator and item.
231 if line_len > 0 && line_len + 1 + total_width > formatting.shape.width {
233 result.push_str(indent_str);
242 line_len += total_width;
248 if let Some(ref comment) = item.pre_comment {
249 // Block style in non-vertical mode.
250 let block_mode = tactic != DefinitiveListTactic::Vertical;
251 // Width restriction is only relevant in vertical mode.
253 try_opt!(rewrite_comment(comment, block_mode, formatting.shape, formatting.config));
254 result.push_str(&comment);
256 if tactic == DefinitiveListTactic::Vertical {
258 result.push_str(indent_str);
264 result.push_str(&inner_item[..]);
267 if tactic != DefinitiveListTactic::Vertical && item.post_comment.is_some() {
268 let comment = item.post_comment.as_ref().unwrap();
269 let formatted_comment = try_opt!(rewrite_comment(comment,
271 Shape::legacy(formatting.shape.width, Indent::empty()),
275 result.push_str(&formatted_comment);
279 result.push_str(formatting.separator);
282 if tactic == DefinitiveListTactic::Vertical && item.post_comment.is_some() {
283 // 1 = space between item and comment.
284 let width = formatting
287 .checked_sub(item_last_line_width + 1)
289 let mut offset = formatting.shape.indent;
290 offset.alignment += item_last_line_width + 1;
291 let comment = item.post_comment.as_ref().unwrap();
293 debug!("Width = {}, offset = {:?}", width, offset);
294 // Use block-style only for the last item or multiline comments.
295 let block_style = !formatting.ends_with_newline && last ||
296 comment.trim().contains('\n') ||
297 comment.trim().len() > width;
299 let formatted_comment = try_opt!(rewrite_comment(comment,
301 Shape::legacy(width, offset),
304 if !formatted_comment.starts_with('\n') {
307 result.push_str(&formatted_comment);
310 if !last && tactic == DefinitiveListTactic::Vertical && item.new_lines {
318 pub struct ListItems<'a, I, F1, F2, F3>
321 codemap: &'a CodeMap,
326 prev_span_end: BytePos,
327 next_span_start: BytePos,
331 impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
332 where I: Iterator<Item = T>,
333 F1: Fn(&T) -> BytePos,
334 F2: Fn(&T) -> BytePos,
335 F3: Fn(&T) -> Option<String>
337 type Item = ListItem;
339 fn next(&mut self) -> Option<Self::Item> {
340 let white_space: &[_] = &[' ', '\t'];
342 self.inner.next().map(|item| {
343 let mut new_lines = false;
345 let pre_snippet = self.codemap
346 .span_to_snippet(codemap::mk_sp(self.prev_span_end, (self.get_lo)(&item)))
348 let trimmed_pre_snippet = pre_snippet.trim();
349 let has_pre_comment = trimmed_pre_snippet.contains("//") ||
350 trimmed_pre_snippet.contains("/*");
351 let pre_comment = if has_pre_comment {
352 Some(trimmed_pre_snippet.to_owned())
358 let next_start = match self.inner.peek() {
359 Some(next_item) => (self.get_lo)(next_item),
360 None => self.next_span_start,
362 let post_snippet = self.codemap
363 .span_to_snippet(codemap::mk_sp((self.get_hi)(&item), next_start))
366 let comment_end = match self.inner.peek() {
368 let mut block_open_index = post_snippet.find("/*");
369 // check if it realy is a block comment (and not //*)
370 if let Some(i) = block_open_index {
371 if i > 0 && &post_snippet[i - 1..i] == "/" {
372 block_open_index = None;
375 let newline_index = post_snippet.find('\n');
376 let separator_index = post_snippet.find_uncommented(",").unwrap();
378 match (block_open_index, newline_index) {
379 // Separator before comment, with the next item on same line.
380 // Comment belongs to next item.
381 (Some(i), None) if i > separator_index => separator_index + 1,
382 // Block-style post-comment before the separator.
384 cmp::max(find_comment_end(&post_snippet[i..]).unwrap() + i,
387 // Block-style post-comment. Either before or after the separator.
388 (Some(i), Some(j)) if i < j => {
389 cmp::max(find_comment_end(&post_snippet[i..]).unwrap() + i,
392 // Potential *single* line comment.
393 (_, Some(j)) if j > separator_index => j + 1,
394 _ => post_snippet.len(),
399 .find_uncommented(self.terminator)
400 .unwrap_or(post_snippet.len())
404 if !post_snippet.is_empty() && comment_end > 0 {
405 // Account for extra whitespace between items. This is fiddly
406 // because of the way we divide pre- and post- comments.
408 // Everything from the separator to the next item.
409 let test_snippet = &post_snippet[comment_end - 1..];
410 let first_newline = test_snippet.find('\n').unwrap_or(test_snippet.len());
411 // From the end of the first line of comments.
412 let test_snippet = &test_snippet[first_newline..];
413 let first = test_snippet
414 .find(|c: char| !c.is_whitespace())
415 .unwrap_or(test_snippet.len());
416 // From the end of the first line of comments to the next non-whitespace char.
417 let test_snippet = &test_snippet[..first];
419 if test_snippet.chars().filter(|c| c == &'\n').count() > 1 {
420 // There were multiple line breaks which got trimmed to nothing.
425 // Cleanup post-comment: strip separators and whitespace.
426 self.prev_span_end = (self.get_hi)(&item) + BytePos(comment_end as u32);
427 let post_snippet = post_snippet[..comment_end].trim();
429 let post_snippet_trimmed = if post_snippet.starts_with(',') {
430 post_snippet[1..].trim_matches(white_space)
431 } else if post_snippet.ends_with(',') {
432 post_snippet[..(post_snippet.len() - 1)].trim_matches(white_space)
437 let post_comment = if !post_snippet_trimmed.is_empty() {
438 Some(post_snippet_trimmed.to_owned())
444 pre_comment: pre_comment,
445 item: (self.get_item_string)(&item),
446 post_comment: post_comment,
447 new_lines: new_lines,
453 // Creates an iterator over a list's items with associated comments.
454 pub fn itemize_list<'a, T, I, F1, F2, F3>(codemap: &'a CodeMap,
460 prev_span_end: BytePos,
461 next_span_start: BytePos)
462 -> ListItems<'a, I, F1, F2, F3>
463 where I: Iterator<Item = T>,
464 F1: Fn(&T) -> BytePos,
465 F2: Fn(&T) -> BytePos,
466 F3: Fn(&T) -> Option<String>
470 inner: inner.peekable(),
473 get_item_string: get_item_string,
474 prev_span_end: prev_span_end,
475 next_span_start: next_span_start,
476 terminator: terminator,
480 fn needs_trailing_separator(separator_tactic: SeparatorTactic,
481 list_tactic: DefinitiveListTactic)
483 match separator_tactic {
484 SeparatorTactic::Always => true,
485 SeparatorTactic::Vertical => list_tactic == DefinitiveListTactic::Vertical,
486 SeparatorTactic::Never => false,
490 /// Returns the count and total width of the list items.
491 fn calculate_width<I, T>(items: I) -> (usize, usize)
492 where I: IntoIterator<Item = T>,
497 .map(|item| total_item_width(item.as_ref()))
498 .fold((0, 0), |acc, l| (acc.0 + 1, acc.1 + l))
501 fn total_item_width(item: &ListItem) -> usize {
502 comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..])) +
503 comment_len(item.post_comment.as_ref().map(|x| &(*x)[..])) +
504 item.item.as_ref().map_or(0, |str| str.len())
507 fn comment_len(comment: Option<&str>) -> usize {
510 let text_len = s.trim().len();
512 // We'll put " /*" before and " */" after inline comments.
522 // Compute horizontal and vertical shapes for a struct-lit-like thing.
523 pub fn struct_lit_shape(shape: Shape,
524 context: &RewriteContext,
527 -> Option<(Option<Shape>, Shape)> {
528 let v_shape = match context.config.struct_lit_style() {
529 IndentStyle::Visual => {
530 try_opt!(try_opt!(shape.shrink_left(prefix_width)).sub_width(suffix_width))
532 IndentStyle::Block => {
533 let shape = shape.block_indent(context.config.tab_spaces());
535 width: try_opt!(context.config.max_width().checked_sub(shape.indent.width())),
540 let h_shape = shape.sub_width(prefix_width + suffix_width);
541 Some((h_shape, v_shape))
544 // Compute the tactic for the internals of a struct-lit-like thing.
545 pub fn struct_lit_tactic(h_shape: Option<Shape>,
546 context: &RewriteContext,
548 -> DefinitiveListTactic {
549 if let Some(h_shape) = h_shape {
550 let mut prelim_tactic = match (context.config.struct_lit_style(), items.len()) {
551 (IndentStyle::Visual, 1) => ListTactic::HorizontalVertical,
552 _ => context.config.struct_lit_multiline_style().to_list_tactic(),
555 if prelim_tactic == ListTactic::HorizontalVertical && items.len() > 1 {
557 ListTactic::LimitedHorizontalVertical(context.config.struct_lit_width());
560 definitive_tactic(items, prelim_tactic, h_shape.width)
562 DefinitiveListTactic::Vertical
566 // Given a tactic and possible shapes for horizontal and vertical layout,
567 // come up with the actual shape to use.
568 pub fn shape_for_tactic(tactic: DefinitiveListTactic,
569 h_shape: Option<Shape>,
573 DefinitiveListTactic::Horizontal => h_shape.unwrap(),
578 // Create a ListFormatting object for formatting the internals of a
579 // struct-lit-like thing, that is a series of fields.
580 pub fn struct_lit_formatting<'a>(shape: Shape,
581 tactic: DefinitiveListTactic,
582 context: &'a RewriteContext,
583 force_no_trailing_comma: bool)
584 -> ListFormatting<'a> {
585 let ends_with_newline = context.config.struct_lit_style() != IndentStyle::Visual &&
586 tactic == DefinitiveListTactic::Vertical;
590 trailing_separator: if force_no_trailing_comma {
591 SeparatorTactic::Never
593 context.config.trailing_comma()
596 ends_with_newline: ends_with_newline,
597 config: context.config,