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.
11 // Format list-like macro invocations. These are invocations whose token trees
12 // can be interpreted as expressions and separated by commas.
13 // Note that these token trees do not actually have to be interpreted as
14 // expressions by the compiler. An example of an invocation we would reformat is
15 // foo!( x, y, z ). The token x may represent an identifier in the code, but we
16 // interpreted as an expression.
17 // Macro uses which are not-list like, such as bar!(key => val), will not be
19 // List-like invocations with parentheses will be formatted as function calls,
20 // and those with brackets will be formatted as array literals.
22 use std::collections::HashMap;
26 use syntax::codemap::{BytePos, Span};
27 use syntax::parse::new_parser_from_tts;
28 use syntax::parse::parser::Parser;
29 use syntax::parse::token::{BinOpToken, DelimToken, Token};
30 use syntax::print::pprust;
32 use syntax::tokenstream::{Cursor, ThinTokenStream, TokenStream, TokenTree};
33 use syntax::util::ThinVec;
35 use codemap::SpanUtils;
36 use comment::{contains_comment, remove_trailing_white_spaces, FindUncommented};
37 use expr::rewrite_array;
38 use lists::{itemize_list, write_list, ListFormatting};
40 use rewrite::{Rewrite, RewriteContext};
41 use shape::{Indent, Shape};
42 use utils::{format_visibility, mk_sp, wrap_str};
44 const FORCED_BRACKET_MACROS: &[&str] = &["vec!"];
46 // FIXME: use the enum from libsyntax?
47 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
54 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
55 pub enum MacroPosition {
63 fn opener(&self) -> &'static str {
65 MacroStyle::Parens => "(",
66 MacroStyle::Brackets => "[",
67 MacroStyle::Braces => "{",
79 impl Rewrite for MacroArg {
80 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
82 MacroArg::Expr(ref expr) => expr.rewrite(context, shape),
83 MacroArg::Ty(ref ty) => ty.rewrite(context, shape),
84 MacroArg::Pat(ref pat) => pat.rewrite(context, shape),
89 fn parse_macro_arg(parser: &mut Parser) -> Option<MacroArg> {
90 macro_rules! parse_macro_arg {
91 ($macro_arg: ident, $parser: ident) => {
92 let mut cloned_parser = (*parser).clone();
93 match cloned_parser.$parser() {
95 if parser.sess.span_diagnostic.has_errors() {
96 parser.sess.span_diagnostic.reset_err_count();
99 *parser = cloned_parser;
100 return Some(MacroArg::$macro_arg((*x).clone()));
105 parser.sess.span_diagnostic.reset_err_count();
111 parse_macro_arg!(Expr, parse_expr);
112 parse_macro_arg!(Ty, parse_ty);
113 parse_macro_arg!(Pat, parse_pat);
118 /// Rewrite macro name without using pretty-printer if possible.
119 fn rewrite_macro_name(path: &ast::Path, extra_ident: Option<ast::Ident>) -> String {
120 let name = if path.segments.len() == 1 {
121 // Avoid using pretty-printer in the common case.
122 format!("{}!", path.segments[0].identifier)
127 Some(ident) if ident != symbol::keywords::Invalid.ident() => format!("{} {}", name, ident),
132 pub fn rewrite_macro(
134 extra_ident: Option<ast::Ident>,
135 context: &RewriteContext,
137 position: MacroPosition,
138 ) -> Option<String> {
139 let context = &mut context.clone();
140 context.inside_macro = true;
141 if context.config.use_try_shorthand() {
142 if let Some(expr) = convert_try_mac(mac, context) {
143 context.inside_macro = false;
144 return expr.rewrite(context, shape);
148 let original_style = macro_style(mac, context);
150 let macro_name = rewrite_macro_name(&mac.node.path, extra_ident);
152 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
158 let ts: TokenStream = mac.node.stream();
159 let has_comment = contains_comment(context.snippet(mac.span));
160 if ts.is_empty() && !has_comment {
162 MacroStyle::Parens if position == MacroPosition::Item => {
163 Some(format!("{}();", macro_name))
165 MacroStyle::Parens => Some(format!("{}()", macro_name)),
166 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
167 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
170 // Format well-known macros which cannot be parsed as a valid AST.
171 // TODO: Maybe add more macros?
172 if macro_name == "lazy_static!" && !has_comment {
173 if let success @ Some(..) = format_lazy_static(context, shape, &ts) {
178 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
179 let mut arg_vec = Vec::new();
180 let mut vec_with_semi = false;
181 let mut trailing_comma = false;
183 if MacroStyle::Braces != style {
185 match parse_macro_arg(&mut parser) {
186 Some(arg) => arg_vec.push(arg),
187 None => return Some(context.snippet(mac.span).to_owned()),
194 // Try to parse `vec![expr; expr]`
195 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
197 if parser.token != Token::Eof {
198 match parse_macro_arg(&mut parser) {
202 if parser.token == Token::Eof && arg_vec.len() == 2 {
203 vec_with_semi = true;
207 None => return Some(context.snippet(mac.span).to_owned()),
211 return Some(context.snippet(mac.span).to_owned());
213 _ => return Some(context.snippet(mac.span).to_owned()),
218 if parser.token == Token::Eof {
219 trailing_comma = true;
226 MacroStyle::Parens => {
227 // Format macro invocation as function call, preserve the trailing
228 // comma because not all macros support them.
229 overflow::rewrite_with_parens(
232 &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..],
235 context.config.width_heuristics().fn_call_width,
237 Some(SeparatorTactic::Always)
239 Some(SeparatorTactic::Never)
241 ).map(|rw| match position {
242 MacroPosition::Item => format!("{};", rw),
246 MacroStyle::Brackets => {
247 let mac_shape = shape.offset_left(macro_name.len())?;
248 // Handle special case: `vec![expr; expr]`
250 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
256 let total_overhead = lbr.len() + rbr.len() + 6;
257 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
258 let lhs = arg_vec[0].rewrite(context, nested_shape)?;
259 let rhs = arg_vec[1].rewrite(context, nested_shape)?;
260 if !lhs.contains('\n') && !rhs.contains('\n')
261 && lhs.len() + rhs.len() + total_overhead <= shape.width
263 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
269 nested_shape.indent.to_string_with_newline(context.config),
271 nested_shape.indent.to_string_with_newline(context.config),
273 shape.indent.to_string_with_newline(context.config),
278 // If we are rewriting `vec!` macro or other special macros,
279 // then we can rewrite this as an usual array literal.
280 // Otherwise, we must preserve the original existence of trailing comma.
281 if FORCED_BRACKET_MACROS.contains(¯o_name.as_str()) {
282 context.inside_macro = false;
283 trailing_comma = false;
285 // Convert `MacroArg` into `ast::Expr`, as `rewrite_array` only accepts the latter.
289 .span_after(mac.span, original_style.opener()),
290 mac.span.hi() - BytePos(1),
292 let arg_vec = &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..];
293 let rewrite = rewrite_array(arg_vec, sp, context, mac_shape, trailing_comma)?;
294 let comma = match position {
295 MacroPosition::Item => ";",
299 Some(format!("{}{}{}", macro_name, rewrite, comma))
302 MacroStyle::Braces => {
303 // Skip macro invocations with braces, for now.
304 indent_macro_snippet(context, context.snippet(mac.span), shape.indent)
309 pub fn rewrite_macro_def(
310 context: &RewriteContext,
315 vis: &ast::Visibility,
317 ) -> Option<String> {
318 let snippet = Some(remove_trailing_white_spaces(context.snippet(span)));
319 if snippet.as_ref().map_or(true, |s| s.ends_with(';')) {
323 let mut parser = MacroParser::new(def.stream().into_trees());
324 let parsed_def = match parser.parse() {
326 None => return snippet,
329 let mut result = if def.legacy {
330 String::from("macro_rules!")
332 format!("{}macro", format_visibility(vis))
336 result += &ident.name.as_str();
338 let multi_branch_style = def.legacy || parsed_def.branches.len() != 1;
340 let arm_shape = if multi_branch_style {
342 .block_indent(context.config.tab_spaces())
343 .with_max_width(context.config)
348 let branch_items = itemize_list(
349 context.snippet_provider,
350 parsed_def.branches.iter(),
353 |branch| branch.span.lo(),
354 |branch| branch.span.hi(),
355 |branch| branch.rewrite(context, arm_shape, multi_branch_style),
356 context.snippet_provider.span_after(span, "{"),
359 ).collect::<Vec<_>>();
361 let fmt = ListFormatting {
362 tactic: DefinitiveListTactic::Vertical,
363 separator: if def.legacy { ";" } else { "" },
364 trailing_separator: SeparatorTactic::Always,
365 separator_place: SeparatorPlace::Back,
367 ends_with_newline: true,
368 preserve_newline: true,
369 config: context.config,
372 if multi_branch_style {
374 result += &arm_shape.indent.to_string_with_newline(context.config);
377 result += write_list(&branch_items, &fmt)?.as_str();
379 if multi_branch_style {
380 result += &indent.to_string_with_newline(context.config);
387 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
388 // aren't causing problems.
389 // This should also work for escaped `$` variables, where we leave earlier `$`s.
390 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
391 // Each substitution will require five or six extra bytes.
392 let mut result = String::with_capacity(input.len() + 64);
393 let mut substs = HashMap::new();
394 let mut dollar_count = 0;
395 let mut cur_name = String::new();
397 for c in input.chars() {
400 } else if dollar_count == 0 {
402 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
403 // Terminates a name following one or more dollars.
404 let mut new_name = String::new();
405 let mut old_name = String::new();
407 for _ in 0..(dollar_count - 1) {
412 new_name.push_str(&cur_name);
413 old_name.push_str(&cur_name);
415 result.push_str(&new_name);
416 substs.insert(old_name, new_name);
421 cur_name = String::new();
422 } else if c == '(' && cur_name.is_empty() {
423 // FIXME: Support macro def with repeat.
425 } else if c.is_alphanumeric() {
430 // FIXME: duplicate code
431 if !cur_name.is_empty() {
432 let mut new_name = String::new();
433 let mut old_name = String::new();
435 for _ in 0..(dollar_count - 1) {
440 new_name.push_str(&cur_name);
441 old_name.push_str(&cur_name);
443 result.push_str(&new_name);
444 substs.insert(old_name, new_name);
447 debug!("replace_names `{}` {:?}", result, substs);
449 Some((result, substs))
452 // This is a bit sketchy. The token rules probably need tweaking, but it works
453 // for some common cases. I hope the basic logic is sufficient. Note that the
454 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
455 // and `(`/`)` have special meaning.
457 // We always try and format on one line.
458 // FIXME: Use multi-line when every thing does not fit on one line.
459 fn format_macro_args(toks: ThinTokenStream, shape: Shape) -> Option<String> {
460 let mut result = String::with_capacity(128);
461 let mut insert_space = SpaceState::Never;
463 for tok in (toks.into(): TokenStream).trees() {
465 TokenTree::Token(_, t) => {
466 if !result.is_empty() && force_space_before(&t) {
467 insert_space = SpaceState::Always;
469 if force_no_space_before(&t) {
470 insert_space = SpaceState::Never;
472 match (insert_space, ident_like(&t)) {
473 (SpaceState::Always, _)
474 | (SpaceState::Punctuation, false)
475 | (SpaceState::Ident, true) => {
480 result.push_str(&pprust::token_to_string(&t));
481 insert_space = next_space(&t);
483 TokenTree::Delimited(_, d) => {
484 if let SpaceState::Always = insert_space {
487 let formatted = format_macro_args(d.tts, shape)?;
489 DelimToken::Paren => {
490 result.push_str(&format!("({})", formatted));
491 insert_space = SpaceState::Always;
493 DelimToken::Bracket => {
494 result.push_str(&format!("[{}]", formatted));
495 insert_space = SpaceState::Always;
497 DelimToken::Brace => {
498 result.push_str(&format!(" {{ {} }}", formatted));
499 insert_space = SpaceState::Always;
501 DelimToken::NoDelim => {
502 result.push_str(&format!("{}", formatted));
503 insert_space = SpaceState::Always;
510 if result.len() <= shape.width {
517 // We should insert a space if the next token is a:
518 #[derive(Copy, Clone)]
522 Ident, // Or ident/literal-like thing.
526 fn force_space_before(tok: &Token) -> bool {
545 | Token::Dollar => true,
546 Token::BinOp(bot) => bot != BinOpToken::Star,
551 fn force_no_space_before(tok: &Token) -> bool {
553 Token::Semi | Token::Comma | Token::Dot => true,
554 Token::BinOp(bot) => bot == BinOpToken::Star,
558 fn ident_like(tok: &Token) -> bool {
560 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
565 fn next_space(tok: &Token) -> SpaceState {
578 | Token::BinOp(_) => SpaceState::Punctuation,
583 | Token::OpenDelim(_)
584 | Token::CloseDelim(_)
585 | Token::Whitespace => SpaceState::Never,
587 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
589 _ => SpaceState::Always,
593 /// Tries to convert a macro use into a short hand try expression. Returns None
594 /// when the macro is not an instance of try! (or parsing the inner expression
596 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
597 if &format!("{}", mac.node.path)[..] == "try" {
598 let ts: TokenStream = mac.node.tts.clone().into();
599 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
602 id: ast::NodeId::new(0), // dummy value
603 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
604 span: mac.span, // incorrect span, but shouldn't matter too much
605 attrs: ThinVec::new(),
612 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
613 let snippet = context.snippet(mac.span);
614 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
615 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
616 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
618 if paren_pos < bracket_pos && paren_pos < brace_pos {
620 } else if bracket_pos < brace_pos {
627 /// Indent each line according to the specified `indent`.
655 fn indent_macro_snippet(
656 context: &RewriteContext,
659 ) -> Option<String> {
660 let mut lines = macro_str.lines();
661 let first_line = lines.next().map(|s| s.trim_right())?;
662 let mut trimmed_lines = Vec::with_capacity(16);
664 let min_prefix_space_width = lines
666 let prefix_space_width = if is_empty_line(line) {
669 Some(get_prefix_space_width(context, line))
671 trimmed_lines.push((line.trim(), prefix_space_width));
677 String::from(first_line) + "\n"
680 .map(|&(line, prefix_space_width)| match prefix_space_width {
681 Some(original_indent_width) => {
682 let new_indent_width = indent.width()
683 + original_indent_width
684 .checked_sub(min_prefix_space_width)
686 let new_indent = Indent::from_width(context.config, new_indent_width);
687 format!("{}{}", new_indent.to_string(context.config), line.trim())
689 None => String::new(),
696 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
701 '\t' => width += context.config.tab_spaces(),
708 fn is_empty_line(s: &str) -> bool {
709 s.is_empty() || s.chars().all(char::is_whitespace)
712 // A very simple parser that just parses a macros 2.0 definition into its branches.
713 // Currently we do not attempt to parse any further than that.
720 // (`(` ... `)` `=>` `{` ... `}`)*
721 fn parse(&mut self) -> Option<Macro> {
722 let mut branches = vec![];
723 while self.toks.look_ahead(1).is_some() {
724 branches.push(self.parse_branch()?);
727 Some(Macro { branches })
730 // `(` ... `)` `=>` `{` ... `}`
731 fn parse_branch(&mut self) -> Option<MacroBranch> {
732 let tok = self.toks.next()?;
733 let (lo, args_paren_kind) = match tok {
734 TokenTree::Token(..) => return None,
735 TokenTree::Delimited(sp, ref d) => (sp.lo(), d.delim),
737 let args = tok.joint().into();
738 match self.toks.next()? {
739 TokenTree::Token(_, Token::FatArrow) => {}
742 let (mut hi, body) = match self.toks.next()? {
743 TokenTree::Token(..) => return None,
744 TokenTree::Delimited(sp, _) => {
745 let data = sp.data();
748 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt),
752 if let Some(TokenTree::Token(sp, Token::Semi)) = self.toks.look_ahead(0) {
765 // A parsed macros 2.0 macro definition.
767 branches: Vec<MacroBranch>,
770 // FIXME: it would be more efficient to use references to the token streams
771 // rather than clone them, if we can make the borrowing work out.
774 args_paren_kind: DelimToken,
775 args: ThinTokenStream,
782 context: &RewriteContext,
784 multi_branch_style: bool,
785 ) -> Option<String> {
786 // Only attempt to format function-like macros.
787 if self.args_paren_kind != DelimToken::Paren {
788 // FIXME(#1539): implement for non-sugared macros.
793 let mut result = format_macro_args(self.args.clone(), shape.sub_width(5)?)?;
795 if multi_branch_style {
799 // The macro body is the most interesting part. It might end up as various
800 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
801 // parsed as regular Rust code (and note that these can be escaped using
802 // `$$`). We'll try and format like an AST node, but we'll substitute
803 // variables for new names with the same length first.
805 let old_body = context.snippet(self.body).trim();
806 let (body_str, substs) = replace_names(old_body)?;
808 let mut config = context.config.clone();
809 config.set().hide_parse_errors(true);
813 let has_block_body = old_body.starts_with('{');
815 let body_indent = if has_block_body {
818 // We'll hack the indent below, take this into account when formatting,
819 let body_indent = shape.indent.block_indent(&config);
820 let new_width = config.max_width() - body_indent.width();
821 config.set().max_width(new_width);
825 // First try to format as items, then as statements.
826 let new_body = match ::format_snippet(&body_str, &config) {
827 Some(new_body) => new_body,
828 None => match ::format_code_block(&body_str, &config) {
829 Some(new_body) => new_body,
833 let new_body = wrap_str(new_body, config.max_width(), shape)?;
835 // Indent the body since it is in a block.
836 let indent_str = body_indent.to_string(&config);
837 let mut new_body = new_body
840 .fold(String::new(), |mut s, l| {
847 // Undo our replacement of macro variables.
848 // FIXME: this could be *much* more efficient.
849 for (old, new) in &substs {
850 if old_body.find(new).is_some() {
851 debug!("rewrite_macro_def: bailing matching variable: `{}`", new);
854 new_body = new_body.replace(new, old);
858 result += new_body.trim();
859 } else if !new_body.is_empty() {
862 result += &shape.indent.to_string(&config);
871 /// Format `lazy_static!` from https://crates.io/crates/lazy_static.
873 /// # Expected syntax
877 /// [pub] static ref NAME_1: TYPE_1 = EXPR_1;
878 /// [pub] static ref NAME_2: TYPE_2 = EXPR_2;
880 /// [pub] static ref NAME_N: TYPE_N = EXPR_N;
883 fn format_lazy_static(context: &RewriteContext, shape: Shape, ts: &TokenStream) -> Option<String> {
884 let mut result = String::with_capacity(1024);
885 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
886 let nested_shape = shape.block_indent(context.config.tab_spaces());
888 result.push_str("lazy_static! {");
889 result.push_str(&nested_shape.indent.to_string_with_newline(context.config));
891 macro parse_or($method:ident $(,)* $($arg:expr),* $(,)*) {
892 match parser.$method($($arg,)*) {
894 if parser.sess.span_diagnostic.has_errors() {
895 parser.sess.span_diagnostic.reset_err_count();
903 parser.sess.span_diagnostic.reset_err_count();
909 while parser.token != Token::Eof {
910 // Parse a `lazy_static!` item.
911 let vis = ::utils::format_visibility(&parse_or!(parse_visibility, false));
912 parser.eat_keyword(symbol::keywords::Static);
913 parser.eat_keyword(symbol::keywords::Ref);
914 let id = parse_or!(parse_ident);
915 parser.eat(&Token::Colon);
916 let ty = parse_or!(parse_ty);
917 parser.eat(&Token::Eq);
918 let expr = parse_or!(parse_expr);
919 parser.eat(&Token::Semi);
921 // Rewrite as a static item.
922 let mut stmt = String::with_capacity(128);
923 stmt.push_str(&format!(
924 "{}static ref {}: {} =",
927 ty.rewrite(context, nested_shape)?
929 result.push_str(&::expr::rewrite_assign_rhs(
933 nested_shape.sub_width(1)?,
936 if parser.token != Token::Eof {
937 result.push_str(&nested_shape.indent.to_string_with_newline(context.config));
941 result.push_str(&shape.indent.to_string_with_newline(context.config));
950 use syntax::parse::{parse_stream_from_source_str, ParseSess};
951 use syntax::codemap::{FileName, FilePathMapping};
953 fn format_macro_args_str(s: &str) -> String {
954 let input = parse_stream_from_source_str(
955 FileName::Custom("stdin".to_owned()),
957 &ParseSess::new(FilePathMapping::empty()),
962 indent: Indent::empty(),
965 format_macro_args(input.into(), shape).unwrap()
969 fn test_format_macro_args() {
970 assert_eq!(format_macro_args_str(""), "".to_owned());
971 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
973 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
974 "$m1: ident, $m2: ident, $x: ident".to_owned()
977 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
978 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
981 format_macro_args_str(
982 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
984 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()