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Diffstat (limited to 'src/tools/rustfmt/src/patterns.rs')
| -rw-r--r-- | src/tools/rustfmt/src/patterns.rs | 525 |
1 files changed, 525 insertions, 0 deletions
diff --git a/src/tools/rustfmt/src/patterns.rs b/src/tools/rustfmt/src/patterns.rs new file mode 100644 index 00000000000..6824fc661ba --- /dev/null +++ b/src/tools/rustfmt/src/patterns.rs @@ -0,0 +1,525 @@ +use rustc_ast::ast::{self, BindingMode, Pat, PatField, PatKind, RangeEnd, RangeSyntax}; +use rustc_ast::ptr; +use rustc_span::{BytePos, Span}; + +use crate::comment::{combine_strs_with_missing_comments, FindUncommented}; +use crate::config::lists::*; +use crate::expr::{can_be_overflowed_expr, rewrite_unary_prefix, wrap_struct_field}; +use crate::lists::{ + definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape, + struct_lit_tactic, write_list, ListFormatting, ListItem, Separator, +}; +use crate::macros::{rewrite_macro, MacroPosition}; +use crate::overflow; +use crate::pairs::{rewrite_pair, PairParts}; +use crate::rewrite::{Rewrite, RewriteContext}; +use crate::shape::Shape; +use crate::source_map::SpanUtils; +use crate::spanned::Spanned; +use crate::types::{rewrite_path, PathContext}; +use crate::utils::{format_mutability, mk_sp, mk_sp_lo_plus_one, rewrite_ident}; + +/// Returns `true` if the given pattern is "short". +/// A short pattern is defined by the following grammar: +/// +/// [small, ntp]: +/// - single token +/// - `&[single-line, ntp]` +/// +/// [small]: +/// - `[small, ntp]` +/// - unary tuple constructor `([small, ntp])` +/// - `&[small]` +pub(crate) fn is_short_pattern(pat: &ast::Pat, pat_str: &str) -> bool { + // We also require that the pattern is reasonably 'small' with its literal width. + pat_str.len() <= 20 && !pat_str.contains('\n') && is_short_pattern_inner(pat) +} + +fn is_short_pattern_inner(pat: &ast::Pat) -> bool { + match pat.kind { + ast::PatKind::Rest | ast::PatKind::Wild | ast::PatKind::Lit(_) => true, + ast::PatKind::Ident(_, _, ref pat) => pat.is_none(), + ast::PatKind::Struct(..) + | ast::PatKind::MacCall(..) + | ast::PatKind::Slice(..) + | ast::PatKind::Path(..) + | ast::PatKind::Range(..) => false, + ast::PatKind::Tuple(ref subpats) => subpats.len() <= 1, + ast::PatKind::TupleStruct(ref path, ref subpats) => { + path.segments.len() <= 1 && subpats.len() <= 1 + } + ast::PatKind::Box(ref p) | ast::PatKind::Ref(ref p, _) | ast::PatKind::Paren(ref p) => { + is_short_pattern_inner(&*p) + } + PatKind::Or(ref pats) => pats.iter().all(|p| is_short_pattern_inner(p)), + } +} + +struct RangeOperand<'a>(&'a Option<ptr::P<ast::Expr>>); + +impl<'a> Rewrite for RangeOperand<'a> { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + match &self.0 { + None => Some("".to_owned()), + Some(ref exp) => exp.rewrite(context, shape), + } + } +} + +impl Rewrite for Pat { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + match self.kind { + PatKind::Or(ref pats) => { + let pat_strs = pats + .iter() + .map(|p| p.rewrite(context, shape)) + .collect::<Option<Vec<_>>>()?; + + let use_mixed_layout = pats + .iter() + .zip(pat_strs.iter()) + .all(|(pat, pat_str)| is_short_pattern(pat, pat_str)); + let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect(); + let tactic = if use_mixed_layout { + DefinitiveListTactic::Mixed + } else { + definitive_tactic( + &items, + ListTactic::HorizontalVertical, + Separator::VerticalBar, + shape.width, + ) + }; + let fmt = ListFormatting::new(shape, context.config) + .tactic(tactic) + .separator(" |") + .separator_place(context.config.binop_separator()) + .ends_with_newline(false); + write_list(&items, &fmt) + } + PatKind::Box(ref pat) => rewrite_unary_prefix(context, "box ", &**pat, shape), + PatKind::Ident(binding_mode, ident, ref sub_pat) => { + let (prefix, mutability) = match binding_mode { + BindingMode::ByRef(mutability) => ("ref", mutability), + BindingMode::ByValue(mutability) => ("", mutability), + }; + let mut_infix = format_mutability(mutability).trim(); + let id_str = rewrite_ident(context, ident); + let sub_pat = match *sub_pat { + Some(ref p) => { + // 2 - `@ `. + let width = shape + .width + .checked_sub(prefix.len() + mut_infix.len() + id_str.len() + 2)?; + let lo = context.snippet_provider.span_after(self.span, "@"); + combine_strs_with_missing_comments( + context, + "@", + &p.rewrite(context, Shape::legacy(width, shape.indent))?, + mk_sp(lo, p.span.lo()), + shape, + true, + )? + } + None => "".to_owned(), + }; + + // combine prefix and mut + let (first_lo, first) = if !prefix.is_empty() && !mut_infix.is_empty() { + let hi = context.snippet_provider.span_before(self.span, "mut"); + let lo = context.snippet_provider.span_after(self.span, "ref"); + ( + context.snippet_provider.span_after(self.span, "mut"), + combine_strs_with_missing_comments( + context, + prefix, + mut_infix, + mk_sp(lo, hi), + shape, + true, + )?, + ) + } else if !prefix.is_empty() { + ( + context.snippet_provider.span_after(self.span, "ref"), + prefix.to_owned(), + ) + } else if !mut_infix.is_empty() { + ( + context.snippet_provider.span_after(self.span, "mut"), + mut_infix.to_owned(), + ) + } else { + (self.span.lo(), "".to_owned()) + }; + + let next = if !sub_pat.is_empty() { + let hi = context.snippet_provider.span_before(self.span, "@"); + combine_strs_with_missing_comments( + context, + id_str, + &sub_pat, + mk_sp(ident.span.hi(), hi), + shape, + true, + )? + } else { + id_str.to_owned() + }; + + combine_strs_with_missing_comments( + context, + &first, + &next, + mk_sp(first_lo, ident.span.lo()), + shape, + true, + ) + } + PatKind::Wild => { + if 1 <= shape.width { + Some("_".to_owned()) + } else { + None + } + } + PatKind::Rest => { + if 1 <= shape.width { + Some("..".to_owned()) + } else { + None + } + } + PatKind::Range(ref lhs, ref rhs, ref end_kind) => { + let infix = match end_kind.node { + RangeEnd::Included(RangeSyntax::DotDotDot) => "...", + RangeEnd::Included(RangeSyntax::DotDotEq) => "..=", + RangeEnd::Excluded => "..", + }; + let infix = if context.config.spaces_around_ranges() { + let lhs_spacing = match lhs { + None => "", + Some(_) => " ", + }; + let rhs_spacing = match rhs { + None => "", + Some(_) => " ", + }; + format!("{}{}{}", lhs_spacing, infix, rhs_spacing) + } else { + infix.to_owned() + }; + rewrite_pair( + &RangeOperand(lhs), + &RangeOperand(rhs), + PairParts::infix(&infix), + context, + shape, + SeparatorPlace::Front, + ) + } + PatKind::Ref(ref pat, mutability) => { + let prefix = format!("&{}", format_mutability(mutability)); + rewrite_unary_prefix(context, &prefix, &**pat, shape) + } + PatKind::Tuple(ref items) => rewrite_tuple_pat(items, None, self.span, context, shape), + PatKind::Path(ref q_self, ref path) => { + rewrite_path(context, PathContext::Expr, q_self.as_ref(), path, shape) + } + PatKind::TupleStruct(ref path, ref pat_vec) => { + let path_str = rewrite_path(context, PathContext::Expr, None, path, shape)?; + rewrite_tuple_pat(pat_vec, Some(path_str), self.span, context, shape) + } + PatKind::Lit(ref expr) => expr.rewrite(context, shape), + PatKind::Slice(ref slice_pat) => { + let rw: Vec<String> = slice_pat + .iter() + .map(|p| { + if let Some(rw) = p.rewrite(context, shape) { + rw + } else { + format!("{}", context.snippet(p.span)) + } + }) + .collect(); + Some(format!("[{}]", rw.join(", "))) + } + PatKind::Struct(ref path, ref fields, ellipsis) => { + rewrite_struct_pat(path, fields, ellipsis, self.span, context, shape) + } + PatKind::MacCall(ref mac) => { + rewrite_macro(mac, None, context, shape, MacroPosition::Pat) + } + PatKind::Paren(ref pat) => pat + .rewrite(context, shape.offset_left(1)?.sub_width(1)?) + .map(|inner_pat| format!("({})", inner_pat)), + } + } +} + +fn rewrite_struct_pat( + path: &ast::Path, + fields: &[ast::PatField], + ellipsis: bool, + span: Span, + context: &RewriteContext<'_>, + shape: Shape, +) -> Option<String> { + // 2 = ` {` + let path_shape = shape.sub_width(2)?; + let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?; + + if fields.is_empty() && !ellipsis { + return Some(format!("{} {{}}", path_str)); + } + + let (ellipsis_str, terminator) = if ellipsis { (", ..", "..") } else { ("", "}") }; + + // 3 = ` { `, 2 = ` }`. + let (h_shape, v_shape) = + struct_lit_shape(shape, context, path_str.len() + 3, ellipsis_str.len() + 2)?; + + let items = itemize_list( + context.snippet_provider, + fields.iter(), + terminator, + ",", + |f| { + if f.attrs.is_empty() { + f.span.lo() + } else { + f.attrs.first().unwrap().span.lo() + } + }, + |f| f.span.hi(), + |f| f.rewrite(context, v_shape), + context.snippet_provider.span_after(span, "{"), + span.hi(), + false, + ); + let item_vec = items.collect::<Vec<_>>(); + + let tactic = struct_lit_tactic(h_shape, context, &item_vec); + let nested_shape = shape_for_tactic(tactic, h_shape, v_shape); + let fmt = struct_lit_formatting(nested_shape, tactic, context, false); + + let mut fields_str = write_list(&item_vec, &fmt)?; + let one_line_width = h_shape.map_or(0, |shape| shape.width); + + if ellipsis { + if fields_str.contains('\n') || fields_str.len() > one_line_width { + // Add a missing trailing comma. + if context.config.trailing_comma() == SeparatorTactic::Never { + fields_str.push_str(","); + } + fields_str.push_str("\n"); + fields_str.push_str(&nested_shape.indent.to_string(context.config)); + fields_str.push_str(".."); + } else { + if !fields_str.is_empty() { + // there are preceding struct fields being matched on + if tactic == DefinitiveListTactic::Vertical { + // if the tactic is Vertical, write_list already added a trailing , + fields_str.push_str(" "); + } else { + fields_str.push_str(", "); + } + } + fields_str.push_str(".."); + } + } + + // ast::Pat doesn't have attrs so use &[] + let fields_str = wrap_struct_field(context, &[], &fields_str, shape, v_shape, one_line_width)?; + Some(format!("{} {{{}}}", path_str, fields_str)) +} + +impl Rewrite for PatField { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + let hi_pos = if let Some(last) = self.attrs.last() { + last.span.hi() + } else { + self.pat.span.lo() + }; + + let attrs_str = if self.attrs.is_empty() { + String::from("") + } else { + self.attrs.rewrite(context, shape)? + }; + + let pat_str = self.pat.rewrite(context, shape)?; + if self.is_shorthand { + combine_strs_with_missing_comments( + context, + &attrs_str, + &pat_str, + mk_sp(hi_pos, self.pat.span.lo()), + shape, + false, + ) + } else { + let nested_shape = shape.block_indent(context.config.tab_spaces()); + let id_str = rewrite_ident(context, self.ident); + let one_line_width = id_str.len() + 2 + pat_str.len(); + let pat_and_id_str = if one_line_width <= shape.width { + format!("{}: {}", id_str, pat_str) + } else { + format!( + "{}:\n{}{}", + id_str, + nested_shape.indent.to_string(context.config), + self.pat.rewrite(context, nested_shape)? + ) + }; + combine_strs_with_missing_comments( + context, + &attrs_str, + &pat_and_id_str, + mk_sp(hi_pos, self.pat.span.lo()), + nested_shape, + false, + ) + } + } +} + +#[derive(Debug)] +pub(crate) enum TuplePatField<'a> { + Pat(&'a ptr::P<ast::Pat>), + Dotdot(Span), +} + +impl<'a> Rewrite for TuplePatField<'a> { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + match *self { + TuplePatField::Pat(p) => p.rewrite(context, shape), + TuplePatField::Dotdot(_) => Some("..".to_string()), + } + } +} + +impl<'a> Spanned for TuplePatField<'a> { + fn span(&self) -> Span { + match *self { + TuplePatField::Pat(p) => p.span(), + TuplePatField::Dotdot(span) => span, + } + } +} + +impl<'a> TuplePatField<'a> { + fn is_dotdot(&self) -> bool { + match self { + TuplePatField::Pat(pat) => match pat.kind { + ast::PatKind::Rest => true, + _ => false, + }, + TuplePatField::Dotdot(_) => true, + } + } +} + +pub(crate) fn can_be_overflowed_pat( + context: &RewriteContext<'_>, + pat: &TuplePatField<'_>, + len: usize, +) -> bool { + match *pat { + TuplePatField::Pat(pat) => match pat.kind { + ast::PatKind::Path(..) + | ast::PatKind::Tuple(..) + | ast::PatKind::Struct(..) + | ast::PatKind::TupleStruct(..) => context.use_block_indent() && len == 1, + ast::PatKind::Ref(ref p, _) | ast::PatKind::Box(ref p) => { + can_be_overflowed_pat(context, &TuplePatField::Pat(p), len) + } + ast::PatKind::Lit(ref expr) => can_be_overflowed_expr(context, expr, len), + _ => false, + }, + TuplePatField::Dotdot(..) => false, + } +} + +fn rewrite_tuple_pat( + pats: &[ptr::P<ast::Pat>], + path_str: Option<String>, + span: Span, + context: &RewriteContext<'_>, + shape: Shape, +) -> Option<String> { + let mut pat_vec: Vec<_> = pats.iter().map(|x| TuplePatField::Pat(x)).collect(); + + if pat_vec.is_empty() { + return Some(format!("{}()", path_str.unwrap_or_default())); + } + let wildcard_suffix_len = count_wildcard_suffix_len(context, &pat_vec, span, shape); + let (pat_vec, span) = if context.config.condense_wildcard_suffixes() && wildcard_suffix_len >= 2 + { + let new_item_count = 1 + pat_vec.len() - wildcard_suffix_len; + let sp = pat_vec[new_item_count - 1].span(); + let snippet = context.snippet(sp); + let lo = sp.lo() + BytePos(snippet.find_uncommented("_").unwrap() as u32); + pat_vec[new_item_count - 1] = TuplePatField::Dotdot(mk_sp_lo_plus_one(lo)); + ( + &pat_vec[..new_item_count], + mk_sp(span.lo(), lo + BytePos(1)), + ) + } else { + (&pat_vec[..], span) + }; + + let is_last_pat_dotdot = pat_vec.last().map_or(false, |p| p.is_dotdot()); + let add_comma = path_str.is_none() && pat_vec.len() == 1 && !is_last_pat_dotdot; + let path_str = path_str.unwrap_or_default(); + + overflow::rewrite_with_parens( + &context, + &path_str, + pat_vec.iter(), + shape, + span, + context.config.max_width(), + if add_comma { + Some(SeparatorTactic::Always) + } else { + None + }, + ) +} + +fn count_wildcard_suffix_len( + context: &RewriteContext<'_>, + patterns: &[TuplePatField<'_>], + span: Span, + shape: Shape, +) -> usize { + let mut suffix_len = 0; + + let items: Vec<_> = itemize_list( + context.snippet_provider, + patterns.iter(), + ")", + ",", + |item| item.span().lo(), + |item| item.span().hi(), + |item| item.rewrite(context, shape), + context.snippet_provider.span_after(span, "("), + span.hi() - BytePos(1), + false, + ) + .collect(); + + for item in items.iter().rev().take_while(|i| match i.item { + Some(ref internal_string) if internal_string == "_" => true, + _ => false, + }) { + suffix_len += 1; + + if item.has_comment() { + break; + } + } + + suffix_len +} |