1 // Copyright 2018 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 //! Rewrite a list some items with overflow.
12 // FIXME: Replace `ToExpr` with some enum.
16 use syntax::codemap::Span;
17 use syntax::parse::token::DelimToken;
20 use codemap::SpanUtils;
21 use expr::{is_every_expr_simple, is_nested_call, maybe_get_args_offset, ToExpr};
22 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
23 use rewrite::{Rewrite, RewriteContext};
27 count_newlines, extra_offset, first_line_width, last_line_width, mk_sp, paren_overhead,
32 const SHORT_ITEM_THRESHOLD: usize = 10;
34 pub fn rewrite_with_parens<T>(
35 context: &RewriteContext,
40 item_max_width: usize,
41 force_separator_tactic: Option<SeparatorTactic>,
44 T: Rewrite + ToExpr + Spanned,
55 force_separator_tactic,
60 pub fn rewrite_with_angle_brackets<T>(
61 context: &RewriteContext,
68 T: Rewrite + ToExpr + Spanned,
78 context.config.max_width(),
84 pub fn rewrite_with_square_brackets<T>(
85 context: &RewriteContext,
90 force_separator_tactic: Option<SeparatorTactic>,
91 delim_token: Option<DelimToken>,
94 T: Rewrite + ToExpr + Spanned,
96 let (lhs, rhs) = match delim_token {
97 Some(DelimToken::Paren) => ("(", ")"),
98 Some(DelimToken::Brace) => ("{", "}"),
109 context.config.width_heuristics().array_width,
110 force_separator_tactic,
115 struct Context<'a, T: 'a> {
116 context: &'a RewriteContext<'a>,
119 prefix: &'static str,
120 suffix: &'static str,
121 one_line_shape: Shape,
124 item_max_width: usize,
125 one_line_width: usize,
126 force_separator_tactic: Option<SeparatorTactic>,
127 custom_delims: Option<(&'a str, &'a str)>,
130 impl<'a, T: 'a + Rewrite + ToExpr + Spanned> Context<'a, T> {
132 context: &'a RewriteContext,
137 prefix: &'static str,
138 suffix: &'static str,
139 item_max_width: usize,
140 force_separator_tactic: Option<SeparatorTactic>,
141 custom_delims: Option<(&'a str, &'a str)>,
142 ) -> Context<'a, T> {
144 let paren_overhead = if context.config.spaces_within_parens_and_brackets() {
149 let used_width = extra_offset(ident, shape);
150 let one_line_width = shape
152 .checked_sub(used_width + 2 * paren_overhead)
156 let one_line_shape = shape
157 .offset_left(last_line_width(ident) + 1)
158 .and_then(|shape| shape.sub_width(1))
159 .unwrap_or(Shape { width: 0, ..shape });
160 let nested_shape = shape_from_indent_style(
163 used_width + 2 * paren_overhead,
164 used_width + paren_overhead,
177 force_separator_tactic,
182 fn last_item(&self) -> Option<&&T> {
186 fn items_span(&self) -> Span {
190 .span_after(self.span, self.prefix);
191 mk_sp(span_lo, self.span.hi())
194 fn rewrite_last_item_with_overflow(
196 last_list_item: &mut ListItem,
198 ) -> Option<String> {
199 let last_item = self.last_item()?;
200 let rewrite = if let Some(expr) = last_item.to_expr() {
202 // When overflowing the closure which consists of a single control flow expression,
203 // force to use block if its condition uses multi line.
204 ast::ExprKind::Closure(..) => {
205 // If the argument consists of multiple closures, we do not overflow
207 if closures::args_have_many_closure(self.items) {
210 closures::rewrite_last_closure(self.context, expr, shape)
213 _ => expr.rewrite(self.context, shape),
216 last_item.rewrite(self.context, shape)
219 if let Some(rewrite) = rewrite {
220 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
221 last_list_item.item = rewrite_first_line;
228 fn default_tactic(&self, list_items: &[ListItem]) -> DefinitiveListTactic {
231 ListTactic::LimitedHorizontalVertical(self.item_max_width),
237 fn try_overflow_last_item(&self, list_items: &mut Vec<ListItem>) -> DefinitiveListTactic {
239 let combine_arg_with_callee = self.items.len() == 1
240 && self.items[0].to_expr().is_some()
241 && self.ident.len() + 1 <= self.context.config.tab_spaces();
242 let overflow_last = combine_arg_with_callee || can_be_overflowed(self.context, self.items);
244 // Replace the last item with its first line to see if it fits with
246 let placeholder = if overflow_last {
247 let old_value = *self.context.force_one_line_chain.borrow();
248 if !combine_arg_with_callee {
249 if let Some(expr) = self.last_item().and_then(|item| item.to_expr()) {
250 if let ast::ExprKind::MethodCall(..) = expr.node {
251 self.context.force_one_line_chain.replace(true);
255 let result = last_item_shape(
260 ).and_then(|arg_shape| {
261 self.rewrite_last_item_with_overflow(
262 &mut list_items[self.items.len() - 1],
266 self.context.force_one_line_chain.replace(old_value);
272 let mut tactic = definitive_tactic(
274 ListTactic::LimitedHorizontalVertical(self.item_max_width),
279 // Replace the stub with the full overflowing last argument if the rewrite
280 // succeeded and its first line fits with the other arguments.
281 match (overflow_last, tactic, placeholder) {
282 (true, DefinitiveListTactic::Horizontal, Some(ref overflowed))
283 if self.items.len() == 1 =>
285 // When we are rewriting a nested function call, we restrict the
286 // budget for the inner function to avoid them being deeply nested.
287 // However, when the inner function has a prefix or a suffix
288 // (e.g. `foo() as u32`), this budget reduction may produce poorly
289 // formatted code, where a prefix or a suffix being left on its own
290 // line. Here we explicitlly check those cases.
291 if count_newlines(overflowed) == 1 {
295 .and_then(|last_item| last_item.rewrite(self.context, self.nested_shape));
296 let no_newline = rw.as_ref().map_or(false, |s| !s.contains('\n'));
298 list_items[self.items.len() - 1].item = rw;
300 list_items[self.items.len() - 1].item = Some(overflowed.to_owned());
303 list_items[self.items.len() - 1].item = Some(overflowed.to_owned());
306 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
307 list_items[self.items.len() - 1].item = placeholder;
309 _ if self.items.len() >= 1 => {
310 list_items[self.items.len() - 1].item = self
313 .and_then(|last_item| last_item.rewrite(self.context, self.nested_shape));
315 // Use horizontal layout for a function with a single argument as long as
316 // everything fits in a single line.
317 // `self.one_line_width == 0` means vertical layout is forced.
318 if self.items.len() == 1
319 && self.one_line_width != 0
320 && !list_items[0].has_comment()
321 && !list_items[0].inner_as_ref().contains('\n')
322 && ::lists::total_item_width(&list_items[0]) <= self.one_line_width
324 tactic = DefinitiveListTactic::Horizontal;
326 tactic = self.default_tactic(list_items);
328 if tactic == DefinitiveListTactic::Vertical {
329 if let Some((all_simple, num_args_before)) =
330 maybe_get_args_offset(self.ident, self.items)
332 let one_line = all_simple
333 && definitive_tactic(
334 &list_items[..num_args_before],
335 ListTactic::HorizontalVertical,
337 self.nested_shape.width,
339 == DefinitiveListTactic::Horizontal
340 && definitive_tactic(
341 &list_items[num_args_before + 1..],
342 ListTactic::HorizontalVertical,
344 self.nested_shape.width,
346 == DefinitiveListTactic::Horizontal;
349 tactic = DefinitiveListTactic::SpecialMacro(num_args_before);
351 } else if is_every_expr_simple(self.items) && no_long_items(list_items) {
352 tactic = DefinitiveListTactic::Mixed;
363 fn rewrite_items(&self) -> Option<(bool, String)> {
364 let span = self.items_span();
365 let items = itemize_list(
366 self.context.snippet_provider,
370 |item| item.span().lo(),
371 |item| item.span().hi(),
372 |item| item.rewrite(self.context, self.nested_shape),
377 let mut list_items: Vec<_> = items.collect();
379 // Try letting the last argument overflow to the next line with block
380 // indentation. If its first line fits on one line with the other arguments,
381 // we format the function arguments horizontally.
382 let tactic = self.try_overflow_last_item(&mut list_items);
384 let fmt = ListFormatting {
387 trailing_separator: if let Some(tactic) = self.force_separator_tactic {
389 } else if !self.context.use_block_indent() {
390 SeparatorTactic::Never
391 } else if tactic == DefinitiveListTactic::Mixed {
392 // We are using mixed layout because everything did not fit within a single line.
393 SeparatorTactic::Always
395 self.context.config.trailing_comma()
397 separator_place: SeparatorPlace::Back,
398 shape: self.nested_shape,
399 ends_with_newline: match tactic {
400 DefinitiveListTactic::Vertical | DefinitiveListTactic::Mixed => {
401 self.context.use_block_indent()
405 preserve_newline: false,
406 config: self.context.config,
409 write_list(&list_items, &fmt)
410 .map(|items_str| (tactic == DefinitiveListTactic::Horizontal, items_str))
413 fn wrap_items(&self, items_str: &str, shape: Shape, is_extendable: bool) -> String {
417 .checked_sub(last_line_width(self.ident))
422 let (prefix, suffix) = match self.custom_delims {
423 Some((lhs, rhs)) => (lhs, rhs),
424 _ => (self.prefix, self.suffix),
426 let paren_overhead = paren_overhead(self.context);
427 let fits_one_line = items_str.len() + paren_overhead <= shape.width;
428 let extend_width = if items_str.is_empty() {
431 first_line_width(items_str) + (paren_overhead / 2)
433 let nested_indent_str = self
436 .to_string_with_newline(self.context.config);
437 let indent_str = shape
440 .to_string_with_newline(self.context.config);
441 let mut result = String::with_capacity(
442 self.ident.len() + items_str.len() + 2 + indent_str.len() + nested_indent_str.len(),
444 result.push_str(self.ident);
445 result.push_str(prefix);
446 if !self.context.use_block_indent()
447 || (self.context.inside_macro() && !items_str.contains('\n') && fits_one_line)
448 || (is_extendable && extend_width <= shape.width)
450 if self.context.config.spaces_within_parens_and_brackets() && !items_str.is_empty() {
452 result.push_str(items_str);
455 result.push_str(items_str);
458 if !items_str.is_empty() {
459 result.push_str(&nested_indent_str);
460 result.push_str(items_str);
462 result.push_str(&indent_str);
464 result.push_str(suffix);
468 fn rewrite(&self, shape: Shape) -> Option<String> {
469 let (extendable, items_str) = self.rewrite_items()?;
471 // If we are using visual indent style and failed to format, retry with block indent.
472 if !self.context.use_block_indent()
473 && need_block_indent(&items_str, self.nested_shape)
476 self.context.use_block.replace(true);
477 let result = self.rewrite(shape);
478 self.context.use_block.replace(false);
482 Some(self.wrap_items(&items_str, shape, extendable))
486 fn need_block_indent(s: &str, shape: Shape) -> bool {
487 s.lines().skip(1).any(|s| {
488 s.find(|c| !char::is_whitespace(c))
489 .map_or(false, |w| w + 1 < shape.indent.width())
493 fn can_be_overflowed<'a, T>(context: &RewriteContext, items: &[&T]) -> bool
495 T: Rewrite + Spanned + ToExpr + 'a,
499 .map_or(false, |x| x.can_be_overflowed(context, items.len()))
502 /// Returns a shape for the last argument which is going to be overflowed.
503 fn last_item_shape<T>(
507 args_max_width: usize,
510 T: Rewrite + Spanned + ToExpr,
512 let is_nested_call = lists
515 .and_then(|item| item.to_expr())
516 .map_or(false, is_nested_call);
517 if items.len() == 1 && !is_nested_call {
520 let offset = items.iter().rev().skip(1).fold(0, |acc, i| {
522 acc + 2 + i.inner_as_ref().len()
525 width: min(args_max_width, shape.width),
527 }.offset_left(offset)
530 fn shape_from_indent_style(
531 context: &RewriteContext,
536 if context.use_block_indent() {
540 .block_indent(context.config.tab_spaces())
541 .with_max_width(context.config)
545 let shape = shape.visual_indent(offset);
546 if let Some(shape) = shape.sub_width(overhead) {
549 Shape { width: 0, ..shape }
554 fn no_long_items(list: &[ListItem]) -> bool {
556 .all(|item| !item.has_comment() && item.inner_as_ref().len() <= SHORT_ITEM_THRESHOLD)