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, rewrite_call_inner};
38 use lists::{itemize_list, write_list, ListFormatting};
39 use rewrite::{Rewrite, RewriteContext};
40 use shape::{Indent, Shape};
41 use utils::{format_visibility, mk_sp, wrap_str};
43 const FORCED_BRACKET_MACROS: &[&str] = &["vec!"];
45 // FIXME: use the enum from libsyntax?
46 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
53 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
54 pub enum MacroPosition {
62 fn opener(&self) -> &'static str {
64 MacroStyle::Parens => "(",
65 MacroStyle::Brackets => "[",
66 MacroStyle::Braces => "{",
78 impl Rewrite for MacroArg {
79 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
81 MacroArg::Expr(ref expr) => expr.rewrite(context, shape),
82 MacroArg::Ty(ref ty) => ty.rewrite(context, shape),
83 MacroArg::Pat(ref pat) => pat.rewrite(context, shape),
88 fn parse_macro_arg(parser: &mut Parser) -> Option<MacroArg> {
89 macro_rules! parse_macro_arg {
90 ($macro_arg: ident, $parser: ident) => {
91 let mut cloned_parser = (*parser).clone();
92 match cloned_parser.$parser() {
94 if parser.sess.span_diagnostic.has_errors() {
95 parser.sess.span_diagnostic.reset_err_count();
98 *parser = cloned_parser;
99 return Some(MacroArg::$macro_arg((*x).clone()));
104 parser.sess.span_diagnostic.reset_err_count();
110 parse_macro_arg!(Expr, parse_expr);
111 parse_macro_arg!(Ty, parse_ty);
112 parse_macro_arg!(Pat, parse_pat);
117 /// Rewrite macro name without using pretty-printer if possible.
118 fn rewrite_macro_name(path: &ast::Path, extra_ident: Option<ast::Ident>) -> String {
119 let name = if path.segments.len() == 1 {
120 // Avoid using pretty-printer in the common case.
121 format!("{}!", path.segments[0].identifier)
126 Some(ident) if ident != symbol::keywords::Invalid.ident() => format!("{} {}", name, ident),
131 pub fn rewrite_macro(
133 extra_ident: Option<ast::Ident>,
134 context: &RewriteContext,
136 position: MacroPosition,
137 ) -> Option<String> {
138 let context = &mut context.clone();
139 context.inside_macro = true;
140 if context.config.use_try_shorthand() {
141 if let Some(expr) = convert_try_mac(mac, context) {
142 context.inside_macro = false;
143 return expr.rewrite(context, shape);
147 let original_style = macro_style(mac, context);
149 let macro_name = rewrite_macro_name(&mac.node.path, extra_ident);
151 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
157 let ts: TokenStream = mac.node.stream();
158 let has_comment = contains_comment(context.snippet(mac.span));
159 if ts.is_empty() && !has_comment {
161 MacroStyle::Parens if position == MacroPosition::Item => {
162 Some(format!("{}();", macro_name))
164 MacroStyle::Parens => Some(format!("{}()", macro_name)),
165 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
166 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
169 // Format well-known macros which cannot be parsed as a valid AST.
170 // TODO: Maybe add more macros?
171 if macro_name == "lazy_static!" && !has_comment {
172 if let success @ Some(..) = format_lazy_static(context, shape, &ts) {
177 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
178 let mut arg_vec = Vec::new();
179 let mut vec_with_semi = false;
180 let mut trailing_comma = false;
182 if MacroStyle::Braces != style {
184 match parse_macro_arg(&mut parser) {
185 Some(arg) => arg_vec.push(arg),
186 None => return Some(context.snippet(mac.span).to_owned()),
193 // Try to parse `vec![expr; expr]`
194 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
196 if parser.token != Token::Eof {
197 match parse_macro_arg(&mut parser) {
201 if parser.token == Token::Eof && arg_vec.len() == 2 {
202 vec_with_semi = true;
206 None => return Some(context.snippet(mac.span).to_owned()),
210 return Some(context.snippet(mac.span).to_owned());
212 _ => return Some(context.snippet(mac.span).to_owned()),
217 if parser.token == Token::Eof {
218 trailing_comma = true;
225 MacroStyle::Parens => {
226 // Format macro invocation as function call, forcing no trailing
227 // comma because not all macros support them.
231 &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..],
234 context.config.width_heuristics().fn_call_width,
236 ).map(|rw| match position {
237 MacroPosition::Item => format!("{};", rw),
241 MacroStyle::Brackets => {
242 let mac_shape = shape.offset_left(macro_name.len())?;
243 // Handle special case: `vec![expr; expr]`
245 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
251 let total_overhead = lbr.len() + rbr.len() + 6;
252 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
253 let lhs = arg_vec[0].rewrite(context, nested_shape)?;
254 let rhs = arg_vec[1].rewrite(context, nested_shape)?;
255 if !lhs.contains('\n') && !rhs.contains('\n')
256 && lhs.len() + rhs.len() + total_overhead <= shape.width
258 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
264 nested_shape.indent.to_string_with_newline(context.config),
266 nested_shape.indent.to_string_with_newline(context.config),
268 shape.indent.to_string_with_newline(context.config),
273 // If we are rewriting `vec!` macro or other special macros,
274 // then we can rewrite this as an usual array literal.
275 // Otherwise, we must preserve the original existence of trailing comma.
276 if FORCED_BRACKET_MACROS.contains(¯o_name.as_str()) {
277 context.inside_macro = false;
278 trailing_comma = false;
280 // Convert `MacroArg` into `ast::Expr`, as `rewrite_array` only accepts the latter.
284 .span_after(mac.span, original_style.opener()),
285 mac.span.hi() - BytePos(1),
287 let arg_vec = &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..];
288 let rewrite = rewrite_array(arg_vec, sp, context, mac_shape, trailing_comma)?;
289 let comma = match position {
290 MacroPosition::Item => ";",
294 Some(format!("{}{}{}", macro_name, rewrite, comma))
297 MacroStyle::Braces => {
298 // Skip macro invocations with braces, for now.
299 indent_macro_snippet(context, context.snippet(mac.span), shape.indent)
304 pub fn rewrite_macro_def(
305 context: &RewriteContext,
310 vis: &ast::Visibility,
312 ) -> Option<String> {
313 let snippet = Some(remove_trailing_white_spaces(context.snippet(span)));
314 if snippet.as_ref().map_or(true, |s| s.ends_with(';')) {
318 let mut parser = MacroParser::new(def.stream().into_trees());
319 let parsed_def = match parser.parse() {
321 None => return snippet,
324 let mut result = if def.legacy {
325 String::from("macro_rules!")
327 format!("{}macro", format_visibility(vis))
331 result += &ident.name.as_str();
333 let multi_branch_style = def.legacy || parsed_def.branches.len() != 1;
335 let arm_shape = if multi_branch_style {
337 .block_indent(context.config.tab_spaces())
338 .with_max_width(context.config)
343 let branch_items = itemize_list(
344 context.snippet_provider,
345 parsed_def.branches.iter(),
348 |branch| branch.span.lo(),
349 |branch| branch.span.hi(),
350 |branch| branch.rewrite(context, arm_shape, multi_branch_style),
351 context.snippet_provider.span_after(span, "{"),
354 ).collect::<Vec<_>>();
356 let fmt = ListFormatting {
357 tactic: DefinitiveListTactic::Vertical,
358 separator: if def.legacy { ";" } else { "" },
359 trailing_separator: SeparatorTactic::Always,
360 separator_place: SeparatorPlace::Back,
362 ends_with_newline: true,
363 preserve_newline: true,
364 config: context.config,
367 if multi_branch_style {
369 result += &arm_shape.indent.to_string_with_newline(context.config);
372 result += write_list(&branch_items, &fmt)?.as_str();
374 if multi_branch_style {
375 result += &indent.to_string_with_newline(context.config);
382 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
383 // aren't causing problems.
384 // This should also work for escaped `$` variables, where we leave earlier `$`s.
385 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
386 // Each substitution will require five or six extra bytes.
387 let mut result = String::with_capacity(input.len() + 64);
388 let mut substs = HashMap::new();
389 let mut dollar_count = 0;
390 let mut cur_name = String::new();
392 for c in input.chars() {
395 } else if dollar_count == 0 {
397 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
398 // Terminates a name following one or more dollars.
399 let mut new_name = String::new();
400 let mut old_name = String::new();
402 for _ in 0..(dollar_count - 1) {
407 new_name.push_str(&cur_name);
408 old_name.push_str(&cur_name);
410 result.push_str(&new_name);
411 substs.insert(old_name, new_name);
416 cur_name = String::new();
417 } else if c == '(' && cur_name.is_empty() {
418 // FIXME: Support macro def with repeat.
420 } else if c.is_alphanumeric() {
425 // FIXME: duplicate code
426 if !cur_name.is_empty() {
427 let mut new_name = String::new();
428 let mut old_name = String::new();
430 for _ in 0..(dollar_count - 1) {
435 new_name.push_str(&cur_name);
436 old_name.push_str(&cur_name);
438 result.push_str(&new_name);
439 substs.insert(old_name, new_name);
442 debug!("replace_names `{}` {:?}", result, substs);
444 Some((result, substs))
447 // This is a bit sketchy. The token rules probably need tweaking, but it works
448 // for some common cases. I hope the basic logic is sufficient. Note that the
449 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
450 // and `(`/`)` have special meaning.
452 // We always try and format on one line.
453 // FIXME: Use multi-line when every thing does not fit on one line.
454 fn format_macro_args(toks: ThinTokenStream, shape: Shape) -> Option<String> {
455 let mut result = String::with_capacity(128);
456 let mut insert_space = SpaceState::Never;
458 for tok in (toks.into(): TokenStream).trees() {
460 TokenTree::Token(_, t) => {
461 if !result.is_empty() && force_space_before(&t) {
462 insert_space = SpaceState::Always;
464 if force_no_space_before(&t) {
465 insert_space = SpaceState::Never;
467 match (insert_space, ident_like(&t)) {
468 (SpaceState::Always, _)
469 | (SpaceState::Punctuation, false)
470 | (SpaceState::Ident, true) => {
475 result.push_str(&pprust::token_to_string(&t));
476 insert_space = next_space(&t);
478 TokenTree::Delimited(_, d) => {
479 if let SpaceState::Always = insert_space {
482 let formatted = format_macro_args(d.tts, shape)?;
484 DelimToken::Paren => {
485 result.push_str(&format!("({})", formatted));
486 insert_space = SpaceState::Always;
488 DelimToken::Bracket => {
489 result.push_str(&format!("[{}]", formatted));
490 insert_space = SpaceState::Always;
492 DelimToken::Brace => {
493 result.push_str(&format!(" {{ {} }}", formatted));
494 insert_space = SpaceState::Always;
496 DelimToken::NoDelim => {
497 result.push_str(&format!("{}", formatted));
498 insert_space = SpaceState::Always;
505 if result.len() <= shape.width {
512 // We should insert a space if the next token is a:
513 #[derive(Copy, Clone)]
517 Ident, // Or ident/literal-like thing.
521 fn force_space_before(tok: &Token) -> bool {
540 | Token::Dollar => true,
541 Token::BinOp(bot) => bot != BinOpToken::Star,
546 fn force_no_space_before(tok: &Token) -> bool {
548 Token::Semi | Token::Comma | Token::Dot => true,
549 Token::BinOp(bot) => bot == BinOpToken::Star,
553 fn ident_like(tok: &Token) -> bool {
555 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
560 fn next_space(tok: &Token) -> SpaceState {
573 | Token::BinOp(_) => SpaceState::Punctuation,
578 | Token::OpenDelim(_)
579 | Token::CloseDelim(_)
580 | Token::Whitespace => SpaceState::Never,
582 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
584 _ => SpaceState::Always,
588 /// Tries to convert a macro use into a short hand try expression. Returns None
589 /// when the macro is not an instance of try! (or parsing the inner expression
591 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
592 if &format!("{}", mac.node.path)[..] == "try" {
593 let ts: TokenStream = mac.node.tts.clone().into();
594 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
597 id: ast::NodeId::new(0), // dummy value
598 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
599 span: mac.span, // incorrect span, but shouldn't matter too much
600 attrs: ThinVec::new(),
607 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
608 let snippet = context.snippet(mac.span);
609 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
610 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
611 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
613 if paren_pos < bracket_pos && paren_pos < brace_pos {
615 } else if bracket_pos < brace_pos {
622 /// Indent each line according to the specified `indent`.
650 fn indent_macro_snippet(
651 context: &RewriteContext,
654 ) -> Option<String> {
655 let mut lines = macro_str.lines();
656 let first_line = lines.next().map(|s| s.trim_right())?;
657 let mut trimmed_lines = Vec::with_capacity(16);
659 let min_prefix_space_width = lines
661 let prefix_space_width = if is_empty_line(line) {
664 Some(get_prefix_space_width(context, line))
666 trimmed_lines.push((line.trim(), prefix_space_width));
672 String::from(first_line) + "\n"
675 .map(|&(line, prefix_space_width)| match prefix_space_width {
676 Some(original_indent_width) => {
677 let new_indent_width = indent.width()
678 + original_indent_width
679 .checked_sub(min_prefix_space_width)
681 let new_indent = Indent::from_width(context.config, new_indent_width);
682 format!("{}{}", new_indent.to_string(context.config), line.trim())
684 None => String::new(),
691 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
696 '\t' => width += context.config.tab_spaces(),
703 fn is_empty_line(s: &str) -> bool {
704 s.is_empty() || s.chars().all(char::is_whitespace)
707 // A very simple parser that just parses a macros 2.0 definition into its branches.
708 // Currently we do not attempt to parse any further than that.
715 // (`(` ... `)` `=>` `{` ... `}`)*
716 fn parse(&mut self) -> Option<Macro> {
717 let mut branches = vec![];
718 while self.toks.look_ahead(1).is_some() {
719 branches.push(self.parse_branch()?);
722 Some(Macro { branches })
725 // `(` ... `)` `=>` `{` ... `}`
726 fn parse_branch(&mut self) -> Option<MacroBranch> {
727 let tok = self.toks.next()?;
728 let (lo, args_paren_kind) = match tok {
729 TokenTree::Token(..) => return None,
730 TokenTree::Delimited(sp, ref d) => (sp.lo(), d.delim),
732 let args = tok.joint().into();
733 match self.toks.next()? {
734 TokenTree::Token(_, Token::FatArrow) => {}
737 let (mut hi, body) = match self.toks.next()? {
738 TokenTree::Token(..) => return None,
739 TokenTree::Delimited(sp, _) => {
740 let data = sp.data();
743 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt),
747 if let Some(TokenTree::Token(sp, Token::Semi)) = self.toks.look_ahead(0) {
760 // A parsed macros 2.0 macro definition.
762 branches: Vec<MacroBranch>,
765 // FIXME: it would be more efficient to use references to the token streams
766 // rather than clone them, if we can make the borrowing work out.
769 args_paren_kind: DelimToken,
770 args: ThinTokenStream,
777 context: &RewriteContext,
779 multi_branch_style: bool,
780 ) -> Option<String> {
781 // Only attempt to format function-like macros.
782 if self.args_paren_kind != DelimToken::Paren {
783 // FIXME(#1539): implement for non-sugared macros.
788 let mut result = format_macro_args(self.args.clone(), shape.sub_width(5)?)?;
790 if multi_branch_style {
794 // The macro body is the most interesting part. It might end up as various
795 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
796 // parsed as regular Rust code (and note that these can be escaped using
797 // `$$`). We'll try and format like an AST node, but we'll substitute
798 // variables for new names with the same length first.
800 let old_body = context.snippet(self.body).trim();
801 let (body_str, substs) = replace_names(old_body)?;
803 let mut config = context.config.clone();
804 config.set().hide_parse_errors(true);
808 let has_block_body = old_body.starts_with('{');
810 let body_indent = if has_block_body {
813 // We'll hack the indent below, take this into account when formatting,
814 let body_indent = shape.indent.block_indent(&config);
815 let new_width = config.max_width() - body_indent.width();
816 config.set().max_width(new_width);
820 // First try to format as items, then as statements.
821 let new_body = match ::format_snippet(&body_str, &config) {
822 Some(new_body) => new_body,
823 None => match ::format_code_block(&body_str, &config) {
824 Some(new_body) => new_body,
828 let new_body = wrap_str(new_body, config.max_width(), shape)?;
830 // Indent the body since it is in a block.
831 let indent_str = body_indent.to_string(&config);
832 let mut new_body = new_body
835 .fold(String::new(), |mut s, l| {
842 // Undo our replacement of macro variables.
843 // FIXME: this could be *much* more efficient.
844 for (old, new) in &substs {
845 if old_body.find(new).is_some() {
846 debug!("rewrite_macro_def: bailing matching variable: `{}`", new);
849 new_body = new_body.replace(new, old);
853 result += new_body.trim();
854 } else if !new_body.is_empty() {
857 result += &shape.indent.to_string(&config);
866 /// Format `lazy_static!` from https://crates.io/crates/lazy_static.
868 /// # Expected syntax
872 /// [pub] static ref NAME_1: TYPE_1 = EXPR_1;
873 /// [pub] static ref NAME_2: TYPE_2 = EXPR_2;
875 /// [pub] static ref NAME_N: TYPE_N = EXPR_N;
878 fn format_lazy_static(context: &RewriteContext, shape: Shape, ts: &TokenStream) -> Option<String> {
879 let mut result = String::with_capacity(1024);
880 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
881 let nested_shape = shape.block_indent(context.config.tab_spaces());
883 result.push_str("lazy_static! {");
884 result.push_str(&nested_shape.indent.to_string_with_newline(context.config));
886 macro parse_or($method:ident $(,)* $($arg:expr),* $(,)*) {
887 match parser.$method($($arg,)*) {
889 if parser.sess.span_diagnostic.has_errors() {
890 parser.sess.span_diagnostic.reset_err_count();
898 parser.sess.span_diagnostic.reset_err_count();
904 while parser.token != Token::Eof {
905 // Parse a `lazy_static!` item.
906 let vis = ::utils::format_visibility(&parse_or!(parse_visibility, false));
907 parser.eat_keyword(symbol::keywords::Static);
908 parser.eat_keyword(symbol::keywords::Ref);
909 let id = parse_or!(parse_ident);
910 parser.eat(&Token::Colon);
911 let ty = parse_or!(parse_ty);
912 parser.eat(&Token::Eq);
913 let expr = parse_or!(parse_expr);
914 parser.eat(&Token::Semi);
916 // Rewrite as a static item.
917 let mut stmt = String::with_capacity(128);
918 stmt.push_str(&format!(
919 "{}static ref {}: {} =",
922 ty.rewrite(context, nested_shape)?
924 result.push_str(&::expr::rewrite_assign_rhs(
928 nested_shape.sub_width(1)?,
931 if parser.token != Token::Eof {
932 result.push_str(&nested_shape.indent.to_string_with_newline(context.config));
936 result.push_str(&shape.indent.to_string_with_newline(context.config));
945 use syntax::parse::{parse_stream_from_source_str, ParseSess};
946 use syntax::codemap::{FileName, FilePathMapping};
948 fn format_macro_args_str(s: &str) -> String {
949 let input = parse_stream_from_source_str(
950 FileName::Custom("stdin".to_owned()),
952 &ParseSess::new(FilePathMapping::empty()),
957 indent: Indent::empty(),
960 format_macro_args(input.into(), shape).unwrap()
964 fn test_format_macro_args() {
965 assert_eq!(format_macro_args_str(""), "".to_owned());
966 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
968 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
969 "$m1: ident, $m2: ident, $x: ident".to_owned()
972 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
973 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
976 format_macro_args_str(
977 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
979 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()