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 syntax::ast::{self, BindingMode, FieldPat, Pat, PatKind, RangeEnd, RangeSyntax};
14 use syntax::source_map::{self, BytePos, Span};
16 use comment::FindUncommented;
17 use expr::{can_be_overflowed_expr, rewrite_unary_prefix, wrap_struct_field};
19 itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape, struct_lit_tactic,
22 use macros::{rewrite_macro, MacroPosition};
24 use pairs::{rewrite_pair, PairParts};
25 use rewrite::{Rewrite, RewriteContext};
27 use source_map::SpanUtils;
29 use types::{rewrite_path, PathContext};
30 use utils::{format_mutability, mk_sp, rewrite_ident};
32 /// Returns true if the given pattern is short. A short pattern is defined by the following grammer:
36 /// - `&[single-line, ntp]`
40 /// - unary tuple constructor `([small, ntp])`
42 pub fn is_short_pattern(pat: &ast::Pat, pat_str: &str) -> bool {
43 // We also require that the pattern is reasonably 'small' with its literal width.
44 pat_str.len() <= 20 && !pat_str.contains('\n') && is_short_pattern_inner(pat)
47 fn is_short_pattern_inner(pat: &ast::Pat) -> bool {
49 ast::PatKind::Wild | ast::PatKind::Lit(_) => true,
50 ast::PatKind::Ident(_, _, ref pat) => pat.is_none(),
51 ast::PatKind::Struct(..)
52 | ast::PatKind::Mac(..)
53 | ast::PatKind::Slice(..)
54 | ast::PatKind::Path(..)
55 | ast::PatKind::Range(..) => false,
56 ast::PatKind::Tuple(ref subpats, _) => subpats.len() <= 1,
57 ast::PatKind::TupleStruct(ref path, ref subpats, _) => {
58 path.segments.len() <= 1 && subpats.len() <= 1
60 ast::PatKind::Box(ref p) | ast::PatKind::Ref(ref p, _) | ast::PatKind::Paren(ref p) => {
61 is_short_pattern_inner(&*p)
66 impl Rewrite for Pat {
67 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
69 PatKind::Box(ref pat) => rewrite_unary_prefix(context, "box ", &**pat, shape),
70 PatKind::Ident(binding_mode, ident, ref sub_pat) => {
71 let (prefix, mutability) = match binding_mode {
72 BindingMode::ByRef(mutability) => ("ref ", mutability),
73 BindingMode::ByValue(mutability) => ("", mutability),
75 let mut_infix = format_mutability(mutability);
76 let id_str = rewrite_ident(context, ident);
77 let sub_pat = match *sub_pat {
82 .checked_sub(prefix.len() + mut_infix.len() + id_str.len() + 3)?;
85 p.rewrite(context, Shape::legacy(width, shape.indent))?
88 None => "".to_owned(),
91 Some(format!("{}{}{}{}", prefix, mut_infix, id_str, sub_pat))
100 PatKind::Range(ref lhs, ref rhs, ref end_kind) => {
101 let infix = match end_kind.node {
102 RangeEnd::Included(RangeSyntax::DotDotDot) => "...",
103 RangeEnd::Included(RangeSyntax::DotDotEq) => "..=",
104 RangeEnd::Excluded => "..",
106 let infix = if context.config.spaces_around_ranges() {
107 format!(" {} ", infix)
114 PairParts::infix(&infix),
117 SeparatorPlace::Front,
120 PatKind::Ref(ref pat, mutability) => {
121 let prefix = format!("&{}", format_mutability(mutability));
122 rewrite_unary_prefix(context, &prefix, &**pat, shape)
124 PatKind::Tuple(ref items, dotdot_pos) => {
125 rewrite_tuple_pat(items, dotdot_pos, None, self.span, context, shape)
127 PatKind::Path(ref q_self, ref path) => {
128 rewrite_path(context, PathContext::Expr, q_self.as_ref(), path, shape)
130 PatKind::TupleStruct(ref path, ref pat_vec, dotdot_pos) => {
131 let path_str = rewrite_path(context, PathContext::Expr, None, path, shape)?;
141 PatKind::Lit(ref expr) => expr.rewrite(context, shape),
142 PatKind::Slice(ref prefix, ref slice_pat, ref suffix) => {
143 // Rewrite all the sub-patterns.
144 let prefix = prefix.iter().map(|p| p.rewrite(context, shape));
145 let slice_pat = slice_pat
147 .and_then(|p| p.rewrite(context, shape))
148 .map(|rw| Some(format!("{}..", if rw == "_" { "" } else { &rw })));
149 let suffix = suffix.iter().map(|p| p.rewrite(context, shape));
151 // Munge them together.
152 let pats: Option<Vec<String>> =
153 prefix.chain(slice_pat.into_iter()).chain(suffix).collect();
155 // Check that all the rewrites succeeded, and if not return None.
158 // Unwrap all the sub-strings and join them with commas.
159 Some(format!("[{}]", pats.join(", ")))
161 PatKind::Struct(ref path, ref fields, ellipsis) => {
162 rewrite_struct_pat(path, fields, ellipsis, self.span, context, shape)
164 PatKind::Mac(ref mac) => rewrite_macro(mac, None, context, shape, MacroPosition::Pat),
165 PatKind::Paren(ref pat) => pat
166 .rewrite(context, shape.offset_left(1)?.sub_width(1)?)
167 .map(|inner_pat| format!("({})", inner_pat)),
172 fn rewrite_struct_pat(
174 fields: &[source_map::Spanned<ast::FieldPat>],
177 context: &RewriteContext,
179 ) -> Option<String> {
181 let path_shape = shape.sub_width(2)?;
182 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
184 if fields.is_empty() && !ellipsis {
185 return Some(format!("{} {{}}", path_str));
188 let (ellipsis_str, terminator) = if ellipsis { (", ..", "..") } else { ("", "}") };
190 // 3 = ` { `, 2 = ` }`.
191 let (h_shape, v_shape) =
192 struct_lit_shape(shape, context, path_str.len() + 3, ellipsis_str.len() + 2)?;
194 let items = itemize_list(
195 context.snippet_provider,
201 |f| f.node.rewrite(context, v_shape),
202 context.snippet_provider.span_after(span, "{"),
206 let item_vec = items.collect::<Vec<_>>();
208 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
209 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
210 let fmt = struct_lit_formatting(nested_shape, tactic, context, false);
212 let mut fields_str = write_list(&item_vec, &fmt)?;
213 let one_line_width = h_shape.map_or(0, |shape| shape.width);
216 if fields_str.contains('\n') || fields_str.len() > one_line_width {
217 // Add a missing trailing comma.
218 if context.config.trailing_comma() == SeparatorTactic::Never {
219 fields_str.push_str(",");
221 fields_str.push_str("\n");
222 fields_str.push_str(&nested_shape.indent.to_string(context.config));
223 fields_str.push_str("..");
225 if !fields_str.is_empty() {
226 // there are preceding struct fields being matched on
227 if tactic == DefinitiveListTactic::Vertical {
228 // if the tactic is Vertical, write_list already added a trailing ,
229 fields_str.push_str(" ");
231 fields_str.push_str(", ");
234 fields_str.push_str("..");
238 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
239 Some(format!("{} {{{}}}", path_str, fields_str))
242 impl Rewrite for FieldPat {
243 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
244 let pat = self.pat.rewrite(context, shape);
245 if self.is_shorthand {
249 let id_str = rewrite_ident(context, self.ident);
250 let one_line_width = id_str.len() + 2 + pat_str.len();
251 if one_line_width <= shape.width {
252 Some(format!("{}: {}", id_str, pat_str))
254 let nested_shape = shape.block_indent(context.config.tab_spaces());
255 let pat_str = self.pat.rewrite(context, nested_shape)?;
259 nested_shape.indent.to_string(context.config),
267 pub enum TuplePatField<'a> {
268 Pat(&'a ptr::P<ast::Pat>),
272 impl<'a> Rewrite for TuplePatField<'a> {
273 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
275 TuplePatField::Pat(p) => p.rewrite(context, shape),
276 TuplePatField::Dotdot(_) => Some("..".to_string()),
281 impl<'a> Spanned for TuplePatField<'a> {
282 fn span(&self) -> Span {
284 TuplePatField::Pat(p) => p.span(),
285 TuplePatField::Dotdot(span) => span,
290 pub fn can_be_overflowed_pat(context: &RewriteContext, pat: &TuplePatField, len: usize) -> bool {
292 TuplePatField::Pat(pat) => match pat.node {
293 ast::PatKind::Path(..)
294 | ast::PatKind::Tuple(..)
295 | ast::PatKind::Struct(..)
296 | ast::PatKind::TupleStruct(..) => context.use_block_indent() && len == 1,
297 ast::PatKind::Ref(ref p, _) | ast::PatKind::Box(ref p) => {
298 can_be_overflowed_pat(context, &TuplePatField::Pat(p), len)
300 ast::PatKind::Lit(ref expr) => can_be_overflowed_expr(context, expr, len),
303 TuplePatField::Dotdot(..) => false,
307 fn rewrite_tuple_pat(
308 pats: &[ptr::P<ast::Pat>],
309 dotdot_pos: Option<usize>,
310 path_str: Option<String>,
312 context: &RewriteContext,
314 ) -> Option<String> {
315 let mut pat_vec: Vec<_> = pats.into_iter().map(|x| TuplePatField::Pat(x)).collect();
317 if let Some(pos) = dotdot_pos {
318 let prev = if pos == 0 {
321 pats[pos - 1].span().hi()
323 let next = if pos + 1 >= pats.len() {
326 pats[pos + 1].span().lo()
328 let dot_span = mk_sp(prev, next);
329 let snippet = context.snippet(dot_span);
330 let lo = dot_span.lo() + BytePos(snippet.find_uncommented("..").unwrap() as u32);
331 let dotdot = TuplePatField::Dotdot(Span::new(
335 source_map::NO_EXPANSION,
337 pat_vec.insert(pos, dotdot);
339 if pat_vec.is_empty() {
340 return Some(format!("{}()", path_str.unwrap_or_default()));
342 let wildcard_suffix_len = count_wildcard_suffix_len(context, &pat_vec, span, shape);
343 let (pat_vec, span, condensed) =
344 if context.config.condense_wildcard_suffixes() && wildcard_suffix_len >= 2 {
345 let new_item_count = 1 + pat_vec.len() - wildcard_suffix_len;
346 let sp = pat_vec[new_item_count - 1].span();
347 let snippet = context.snippet(sp);
348 let lo = sp.lo() + BytePos(snippet.find_uncommented("_").unwrap() as u32);
349 pat_vec[new_item_count - 1] = TuplePatField::Dotdot(mk_sp(lo, lo + BytePos(1)));
351 &pat_vec[..new_item_count],
352 mk_sp(span.lo(), lo + BytePos(1)),
356 (&pat_vec[..], span, false)
359 // add comma if `(x,)`
360 let add_comma = path_str.is_none() && pat_vec.len() == 1 && dotdot_pos.is_none() && !condensed;
361 let path_str = path_str.unwrap_or_default();
362 let pat_ref_vec = pat_vec.iter().collect::<Vec<_>>();
364 overflow::rewrite_with_parens(
370 context.config.max_width(),
371 if dotdot_pos.is_some() {
372 Some(SeparatorTactic::Never)
373 } else if add_comma {
374 Some(SeparatorTactic::Always)
381 fn count_wildcard_suffix_len(
382 context: &RewriteContext,
383 patterns: &[TuplePatField],
387 let mut suffix_len = 0;
389 let items: Vec<_> = itemize_list(
390 context.snippet_provider,
394 |item| item.span().lo(),
395 |item| item.span().hi(),
396 |item| item.rewrite(context, shape),
397 context.snippet_provider.span_after(span, "("),
398 span.hi() - BytePos(1),
403 for item in items.iter().rev().take_while(|i| match i.item {
404 Some(ref internal_string) if internal_string == "_" => true,
409 if item.has_comment() {