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};
26 use utils::{count_newlines, extra_offset, first_line_width, last_line_width, mk_sp, paren_overhead};
30 const SHORT_ITEM_THRESHOLD: usize = 10;
32 pub fn rewrite_with_parens<T>(
33 context: &RewriteContext,
38 item_max_width: usize,
39 force_separator_tactic: Option<SeparatorTactic>,
42 T: Rewrite + ToExpr + Spanned,
53 force_separator_tactic,
58 pub fn rewrite_with_angle_brackets<T>(
59 context: &RewriteContext,
66 T: Rewrite + ToExpr + Spanned,
76 context.config.max_width(),
82 pub fn rewrite_with_square_brackets<T>(
83 context: &RewriteContext,
88 force_separator_tactic: Option<SeparatorTactic>,
89 delim_token: Option<DelimToken>,
92 T: Rewrite + ToExpr + Spanned,
94 let (lhs, rhs) = match delim_token {
95 Some(DelimToken::Paren) => ("(", ")"),
96 Some(DelimToken::Brace) => ("{", "}"),
107 context.config.width_heuristics().array_width,
108 force_separator_tactic,
113 struct Context<'a, T: 'a> {
114 context: &'a RewriteContext<'a>,
117 prefix: &'static str,
118 suffix: &'static str,
119 one_line_shape: Shape,
122 item_max_width: usize,
123 one_line_width: usize,
124 force_separator_tactic: Option<SeparatorTactic>,
125 custom_delims: Option<(&'a str, &'a str)>,
128 impl<'a, T: 'a + Rewrite + ToExpr + Spanned> Context<'a, T> {
130 context: &'a RewriteContext,
135 prefix: &'static str,
136 suffix: &'static str,
137 item_max_width: usize,
138 force_separator_tactic: Option<SeparatorTactic>,
139 custom_delims: Option<(&'a str, &'a str)>,
140 ) -> Context<'a, T> {
142 let paren_overhead = if context.config.spaces_within_parens_and_brackets() {
147 let used_width = extra_offset(ident, shape);
148 let one_line_width = shape
150 .checked_sub(used_width + 2 * paren_overhead)
154 let one_line_shape = shape
155 .offset_left(last_line_width(ident) + 1)
156 .and_then(|shape| shape.sub_width(1))
157 .unwrap_or(Shape { width: 0, ..shape });
158 let nested_shape = shape_from_indent_style(
161 used_width + 2 * paren_overhead,
162 used_width + paren_overhead,
175 force_separator_tactic,
180 fn last_item(&self) -> Option<&&T> {
184 fn items_span(&self) -> Span {
185 let span_lo = self.context
187 .span_after(self.span, self.prefix);
188 mk_sp(span_lo, self.span.hi())
191 fn rewrite_last_item_with_overflow(
193 last_list_item: &mut ListItem,
195 ) -> Option<String> {
196 let last_item = self.last_item()?;
197 let rewrite = if let Some(expr) = last_item.to_expr() {
199 // When overflowing the closure which consists of a single control flow expression,
200 // force to use block if its condition uses multi line.
201 ast::ExprKind::Closure(..) => {
202 // If the argument consists of multiple closures, we do not overflow
204 if closures::args_have_many_closure(self.items) {
207 closures::rewrite_last_closure(self.context, expr, shape)
210 _ => expr.rewrite(self.context, shape),
213 last_item.rewrite(self.context, shape)
216 if let Some(rewrite) = rewrite {
217 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
218 last_list_item.item = rewrite_first_line;
225 fn default_tactic(&self, list_items: &[ListItem]) -> DefinitiveListTactic {
228 ListTactic::LimitedHorizontalVertical(self.item_max_width),
234 fn try_overflow_last_item(&self, list_items: &mut Vec<ListItem>) -> DefinitiveListTactic {
236 let combine_arg_with_callee = self.items.len() == 1 && self.items[0].to_expr().is_some()
237 && self.ident.len() + 1 <= self.context.config.tab_spaces();
238 let overflow_last = combine_arg_with_callee || can_be_overflowed(self.context, self.items);
240 // Replace the last item with its first line to see if it fits with
242 let placeholder = if overflow_last {
243 let old_value = *self.context.force_one_line_chain.borrow();
244 if !combine_arg_with_callee {
245 if let Some(expr) = self.last_item().and_then(|item| item.to_expr()) {
246 if let ast::ExprKind::MethodCall(..) = expr.node {
247 self.context.force_one_line_chain.replace(true);
251 let result = last_item_shape(
256 ).and_then(|arg_shape| {
257 self.rewrite_last_item_with_overflow(
258 &mut list_items[self.items.len() - 1],
262 self.context.force_one_line_chain.replace(old_value);
268 let mut tactic = definitive_tactic(
270 ListTactic::LimitedHorizontalVertical(self.item_max_width),
275 // Replace the stub with the full overflowing last argument if the rewrite
276 // succeeded and its first line fits with the other arguments.
277 match (overflow_last, tactic, placeholder) {
278 (true, DefinitiveListTactic::Horizontal, Some(ref overflowed))
279 if self.items.len() == 1 =>
281 // When we are rewriting a nested function call, we restrict the
282 // budget for the inner function to avoid them being deeply nested.
283 // However, when the inner function has a prefix or a suffix
284 // (e.g. `foo() as u32`), this budget reduction may produce poorly
285 // formatted code, where a prefix or a suffix being left on its own
286 // line. Here we explicitlly check those cases.
287 if count_newlines(overflowed) == 1 {
290 .and_then(|last_item| last_item.rewrite(self.context, self.nested_shape));
291 let no_newline = rw.as_ref().map_or(false, |s| !s.contains('\n'));
293 list_items[self.items.len() - 1].item = rw;
295 list_items[self.items.len() - 1].item = Some(overflowed.to_owned());
298 list_items[self.items.len() - 1].item = Some(overflowed.to_owned());
301 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
302 list_items[self.items.len() - 1].item = placeholder;
304 _ if self.items.len() >= 1 => {
305 list_items[self.items.len() - 1].item = self.items
307 .and_then(|last_item| last_item.rewrite(self.context, self.nested_shape));
309 // Use horizontal layout for a function with a single argument as long as
310 // everything fits in a single line.
311 // `self.one_line_width == 0` means vertical layout is forced.
312 if self.items.len() == 1 && self.one_line_width != 0 && !list_items[0].has_comment()
313 && !list_items[0].inner_as_ref().contains('\n')
314 && ::lists::total_item_width(&list_items[0]) <= self.one_line_width
316 tactic = DefinitiveListTactic::Horizontal;
318 tactic = self.default_tactic(list_items);
320 if tactic == DefinitiveListTactic::Vertical {
321 if let Some((all_simple, num_args_before)) =
322 maybe_get_args_offset(self.ident, self.items)
324 let one_line = all_simple
325 && definitive_tactic(
326 &list_items[..num_args_before],
327 ListTactic::HorizontalVertical,
329 self.nested_shape.width,
331 == DefinitiveListTactic::Horizontal
332 && definitive_tactic(
333 &list_items[num_args_before + 1..],
334 ListTactic::HorizontalVertical,
336 self.nested_shape.width,
338 == DefinitiveListTactic::Horizontal;
341 tactic = DefinitiveListTactic::SpecialMacro(num_args_before);
343 } else if is_every_expr_simple(self.items) && no_long_items(list_items) {
344 tactic = DefinitiveListTactic::Mixed;
355 fn rewrite_items(&self) -> Option<(bool, String)> {
356 let span = self.items_span();
357 let items = itemize_list(
358 self.context.snippet_provider,
362 |item| item.span().lo(),
363 |item| item.span().hi(),
364 |item| item.rewrite(self.context, self.nested_shape),
369 let mut list_items: Vec<_> = items.collect();
371 // Try letting the last argument overflow to the next line with block
372 // indentation. If its first line fits on one line with the other arguments,
373 // we format the function arguments horizontally.
374 let tactic = self.try_overflow_last_item(&mut list_items);
376 let fmt = ListFormatting {
379 trailing_separator: if let Some(tactic) = self.force_separator_tactic {
381 } else if !self.context.use_block_indent() {
382 SeparatorTactic::Never
383 } else if tactic == DefinitiveListTactic::Mixed {
384 // We are using mixed layout because everything did not fit within a single line.
385 SeparatorTactic::Always
387 self.context.config.trailing_comma()
389 separator_place: SeparatorPlace::Back,
390 shape: self.nested_shape,
391 ends_with_newline: match tactic {
392 DefinitiveListTactic::Vertical | DefinitiveListTactic::Mixed => {
393 self.context.use_block_indent()
397 preserve_newline: false,
398 config: self.context.config,
401 write_list(&list_items, &fmt)
402 .map(|items_str| (tactic == DefinitiveListTactic::Horizontal, items_str))
405 fn wrap_items(&self, items_str: &str, shape: Shape, is_extendable: bool) -> String {
409 .checked_sub(last_line_width(self.ident))
414 let (prefix, suffix) = match self.custom_delims {
415 Some((lhs, rhs)) => (lhs, rhs),
416 _ => (self.prefix, self.suffix),
418 let paren_overhead = paren_overhead(self.context);
419 let fits_one_line = items_str.len() + paren_overhead <= shape.width;
420 let extend_width = if items_str.is_empty() {
425 let nested_indent_str = self.nested_shape
427 .to_string_with_newline(self.context.config);
428 let indent_str = shape
431 .to_string_with_newline(self.context.config);
432 let mut result = String::with_capacity(
433 self.ident.len() + items_str.len() + 2 + indent_str.len() + nested_indent_str.len(),
435 result.push_str(self.ident);
436 result.push_str(prefix);
437 if !self.context.use_block_indent()
438 || (self.context.inside_macro() && !items_str.contains('\n') && fits_one_line)
439 || (is_extendable && extend_width <= shape.width)
441 if self.context.config.spaces_within_parens_and_brackets() && !items_str.is_empty() {
443 result.push_str(items_str);
446 result.push_str(items_str);
449 if !items_str.is_empty() {
450 result.push_str(&nested_indent_str);
451 result.push_str(items_str);
453 result.push_str(&indent_str);
455 result.push_str(suffix);
459 fn rewrite(&self, shape: Shape) -> Option<String> {
460 let (extendable, items_str) = self.rewrite_items()?;
462 // If we are using visual indent style and failed to format, retry with block indent.
463 if !self.context.use_block_indent() && need_block_indent(&items_str, self.nested_shape)
466 self.context.use_block.replace(true);
467 let result = self.rewrite(shape);
468 self.context.use_block.replace(false);
472 Some(self.wrap_items(&items_str, shape, extendable))
476 fn need_block_indent(s: &str, shape: Shape) -> bool {
477 s.lines().skip(1).any(|s| {
478 s.find(|c| !char::is_whitespace(c))
479 .map_or(false, |w| w + 1 < shape.indent.width())
483 fn can_be_overflowed<'a, T>(context: &RewriteContext, items: &[&T]) -> bool
485 T: Rewrite + Spanned + ToExpr + 'a,
489 .map_or(false, |x| x.can_be_overflowed(context, items.len()))
492 /// Returns a shape for the last argument which is going to be overflowed.
493 fn last_item_shape<T>(
497 args_max_width: usize,
500 T: Rewrite + Spanned + ToExpr,
502 let is_nested_call = lists
505 .and_then(|item| item.to_expr())
506 .map_or(false, is_nested_call);
507 if items.len() == 1 && !is_nested_call {
510 let offset = items.iter().rev().skip(1).fold(0, |acc, i| {
512 acc + 2 + i.inner_as_ref().len()
515 width: min(args_max_width, shape.width),
517 }.offset_left(offset)
520 fn shape_from_indent_style(
521 context: &RewriteContext,
526 if context.use_block_indent() {
530 .block_indent(context.config.tab_spaces())
531 .with_max_width(context.config)
535 let shape = shape.visual_indent(offset);
536 if let Some(shape) = shape.sub_width(overhead) {
539 Shape { width: 0, ..shape }
544 fn no_long_items(list: &[ListItem]) -> bool {
546 .all(|item| !item.has_comment() && item.inner_as_ref().len() <= SHORT_ITEM_THRESHOLD)