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};
13 use syntax::codemap::{self, BytePos, Span};
16 use codemap::SpanUtils;
17 use comment::FindUncommented;
18 use expr::{can_be_overflowed_expr, rewrite_pair, rewrite_unary_prefix, wrap_struct_field,
20 use lists::{itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape,
21 struct_lit_tactic, write_list};
22 use macros::{rewrite_macro, MacroPosition};
24 use rewrite::{Rewrite, RewriteContext};
27 use types::{rewrite_path, PathContext};
28 use utils::{format_mutability, mk_sp};
30 /// Returns true if the given pattern is short. A short pattern is defined by the following grammer:
34 /// - `&[single-line, ntp]`
38 /// - unary tuple constructor `([small, ntp])`
40 pub fn is_short_pattern(pat: &ast::Pat, pat_str: &str) -> bool {
41 // We also require that the pattern is reasonably 'small' with its literal width.
42 pat_str.len() <= 20 && !pat_str.contains('\n') && is_short_pattern_inner(pat)
45 fn is_short_pattern_inner(pat: &ast::Pat) -> bool {
47 ast::PatKind::Wild | ast::PatKind::Lit(_) => true,
48 ast::PatKind::Ident(_, _, ref pat) => pat.is_none(),
49 ast::PatKind::Struct(..)
50 | ast::PatKind::Mac(..)
51 | ast::PatKind::Slice(..)
52 | ast::PatKind::Path(..)
53 | ast::PatKind::Range(..) => false,
54 ast::PatKind::Tuple(ref subpats, _) => subpats.len() <= 1,
55 ast::PatKind::TupleStruct(ref path, ref subpats, _) => {
56 path.segments.len() <= 1 && subpats.len() <= 1
58 ast::PatKind::Box(ref p) | ast::PatKind::Ref(ref p, _) | ast::PatKind::Paren(ref p) => {
59 is_short_pattern_inner(&*p)
64 impl Rewrite for Pat {
65 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
67 PatKind::Box(ref pat) => rewrite_unary_prefix(context, "box ", &**pat, shape),
68 PatKind::Ident(binding_mode, ident, ref sub_pat) => {
69 let (prefix, mutability) = match binding_mode {
70 BindingMode::ByRef(mutability) => ("ref ", mutability),
71 BindingMode::ByValue(mutability) => ("", mutability),
73 let mut_infix = format_mutability(mutability);
74 let id_str = ident.node.to_string();
75 let sub_pat = match *sub_pat {
80 .checked_sub(prefix.len() + mut_infix.len() + id_str.len() + 3)?;
83 p.rewrite(context, Shape::legacy(width, shape.indent))?
86 None => "".to_owned(),
89 Some(format!("{}{}{}{}", prefix, mut_infix, id_str, sub_pat))
98 PatKind::Range(ref lhs, ref rhs, ref end_kind) => {
99 let infix = match *end_kind {
100 RangeEnd::Included(RangeSyntax::DotDotDot) => "...",
101 RangeEnd::Included(RangeSyntax::DotDotEq) => "..=",
102 RangeEnd::Excluded => "..",
104 let infix = if context.config.spaces_around_ranges() {
105 format!(" {} ", infix)
112 PairParts::new("", &infix, ""),
115 SeparatorPlace::Front,
118 PatKind::Ref(ref pat, mutability) => {
119 let prefix = format!("&{}", format_mutability(mutability));
120 rewrite_unary_prefix(context, &prefix, &**pat, shape)
122 PatKind::Tuple(ref items, dotdot_pos) => {
123 rewrite_tuple_pat(items, dotdot_pos, None, self.span, context, shape)
125 PatKind::Path(ref q_self, ref path) => {
126 rewrite_path(context, PathContext::Expr, q_self.as_ref(), path, shape)
128 PatKind::TupleStruct(ref path, ref pat_vec, dotdot_pos) => {
129 let path_str = rewrite_path(context, PathContext::Expr, None, path, shape)?;
139 PatKind::Lit(ref expr) => expr.rewrite(context, shape),
140 PatKind::Slice(ref prefix, ref slice_pat, ref suffix) => {
141 // Rewrite all the sub-patterns.
142 let prefix = prefix.iter().map(|p| p.rewrite(context, shape));
143 let slice_pat = slice_pat
145 .map(|p| Some(format!("{}..", p.rewrite(context, shape)?)));
146 let suffix = suffix.iter().map(|p| p.rewrite(context, shape));
148 // Munge them together.
149 let pats: Option<Vec<String>> =
150 prefix.chain(slice_pat.into_iter()).chain(suffix).collect();
152 // Check that all the rewrites succeeded, and if not return None.
155 // Unwrap all the sub-strings and join them with commas.
156 let result = if context.config.spaces_within_parens_and_brackets() {
157 format!("[ {} ]", pats.join(", "))
159 format!("[{}]", pats.join(", "))
163 PatKind::Struct(ref path, ref fields, ellipsis) => {
164 rewrite_struct_pat(path, fields, ellipsis, self.span, context, shape)
166 PatKind::Mac(ref mac) => rewrite_macro(mac, None, context, shape, MacroPosition::Pat),
167 PatKind::Paren(ref pat) => pat.rewrite(context, shape.offset_left(1)?.sub_width(1)?)
168 .map(|inner_pat| format!("({})", inner_pat)),
173 fn rewrite_struct_pat(
175 fields: &[codemap::Spanned<ast::FieldPat>],
178 context: &RewriteContext,
180 ) -> Option<String> {
182 let path_shape = shape.sub_width(2)?;
183 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
185 if fields.is_empty() && !ellipsis {
186 return Some(format!("{} {{}}", path_str));
189 let (ellipsis_str, terminator) = if ellipsis { (", ..", "..") } else { ("", "}") };
191 // 3 = ` { `, 2 = ` }`.
192 let (h_shape, v_shape) =
193 struct_lit_shape(shape, context, path_str.len() + 3, ellipsis_str.len() + 2)?;
195 let items = itemize_list(
196 context.snippet_provider,
202 |f| f.node.rewrite(context, v_shape),
203 context.snippet_provider.span_after(span, "{"),
207 let item_vec = items.collect::<Vec<_>>();
209 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
210 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
211 let fmt = struct_lit_formatting(nested_shape, tactic, context, false);
213 let mut fields_str = write_list(&item_vec, &fmt)?;
214 let one_line_width = h_shape.map_or(0, |shape| shape.width);
217 if fields_str.contains('\n') || fields_str.len() > one_line_width {
218 // Add a missing trailing comma.
219 if fmt.trailing_separator == SeparatorTactic::Never {
220 fields_str.push_str(",");
222 fields_str.push_str("\n");
223 fields_str.push_str(&nested_shape.indent.to_string(context.config));
224 fields_str.push_str("..");
226 if !fields_str.is_empty() {
227 // there are preceding struct fields being matched on
228 if fmt.tactic == DefinitiveListTactic::Vertical {
229 // if the tactic is Vertical, write_list already added a trailing ,
230 fields_str.push_str(" ");
232 fields_str.push_str(", ");
235 fields_str.push_str("..");
239 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
240 Some(format!("{} {{{}}}", path_str, fields_str))
243 impl Rewrite for FieldPat {
244 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
245 let pat = self.pat.rewrite(context, shape);
246 if self.is_shorthand {
250 let id_str = self.ident.to_string();
251 let one_line_width = id_str.len() + 2 + pat_str.len();
252 if one_line_width <= shape.width {
253 Some(format!("{}: {}", id_str, pat_str))
255 let nested_shape = shape.block_indent(context.config.tab_spaces());
256 let pat_str = self.pat.rewrite(context, nested_shape)?;
260 nested_shape.indent.to_string(context.config),
268 pub enum TuplePatField<'a> {
269 Pat(&'a ptr::P<ast::Pat>),
273 impl<'a> Rewrite for TuplePatField<'a> {
274 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
276 TuplePatField::Pat(p) => p.rewrite(context, shape),
277 TuplePatField::Dotdot(_) => Some("..".to_string()),
282 impl<'a> Spanned for TuplePatField<'a> {
283 fn span(&self) -> Span {
285 TuplePatField::Pat(p) => p.span(),
286 TuplePatField::Dotdot(span) => span,
291 pub fn can_be_overflowed_pat(context: &RewriteContext, pat: &TuplePatField, len: usize) -> bool {
293 TuplePatField::Pat(pat) => match pat.node {
294 ast::PatKind::Path(..)
295 | ast::PatKind::Tuple(..)
296 | ast::PatKind::Struct(..)
297 | ast::PatKind::TupleStruct(..) => context.use_block_indent() && len == 1,
298 ast::PatKind::Ref(ref p, _) | ast::PatKind::Box(ref p) => {
299 can_be_overflowed_pat(context, &TuplePatField::Pat(p), len)
301 ast::PatKind::Lit(ref expr) => can_be_overflowed_expr(context, expr, len),
304 TuplePatField::Dotdot(..) => false,
308 fn rewrite_tuple_pat(
309 pats: &[ptr::P<ast::Pat>],
310 dotdot_pos: Option<usize>,
311 path_str: Option<String>,
313 context: &RewriteContext,
315 ) -> Option<String> {
316 let mut pat_vec: Vec<_> = pats.into_iter().map(|x| TuplePatField::Pat(x)).collect();
318 if let Some(pos) = dotdot_pos {
319 let prev = if pos == 0 {
322 pats[pos - 1].span().hi()
324 let next = if pos + 1 >= pats.len() {
327 pats[pos + 1].span().lo()
329 let dot_span = mk_sp(prev, next);
330 let snippet = context.snippet(dot_span);
331 let lo = dot_span.lo() + BytePos(snippet.find_uncommented("..").unwrap() as u32);
332 let dotdot = TuplePatField::Dotdot(Span::new(
336 codemap::NO_EXPANSION,
338 pat_vec.insert(pos, dotdot);
341 if pat_vec.is_empty() {
342 return Some(format!("{}()", path_str.unwrap_or_default()));
345 let wildcard_suffix_len = count_wildcard_suffix_len(context, &pat_vec, span, shape);
346 let (pat_vec, span) = if context.config.condense_wildcard_suffixes() && wildcard_suffix_len >= 2
348 let new_item_count = 1 + pat_vec.len() - wildcard_suffix_len;
349 let sp = pat_vec[new_item_count - 1].span();
350 let snippet = context.snippet(sp);
351 let lo = sp.lo() + BytePos(snippet.find_uncommented("_").unwrap() as u32);
352 pat_vec[new_item_count - 1] = TuplePatField::Dotdot(mk_sp(lo, lo + BytePos(1)));
354 &pat_vec[..new_item_count],
355 mk_sp(span.lo(), lo + BytePos(1)),
361 // add comma if `(x,)`
362 let add_comma = path_str.is_none() && pat_vec.len() == 1 && dotdot_pos.is_none();
363 let path_str = path_str.unwrap_or_default();
364 let pat_ref_vec = pat_vec.iter().collect::<Vec<_>>();
366 overflow::rewrite_with_parens(
372 context.config.max_width(),
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),
402 for item in items.iter().rev().take_while(|i| match i.item {
403 Some(ref internal_string) if internal_string == "_" => true,
408 if item.has_comment() {