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;
24 use syntax::codemap::{BytePos, Span};
25 use syntax::parse::new_parser_from_tts;
26 use syntax::parse::parser::Parser;
27 use syntax::parse::token::{BinOpToken, DelimToken, Token};
28 use syntax::print::pprust;
30 use syntax::tokenstream::{Cursor, ThinTokenStream, TokenStream, TokenTree};
31 use syntax::util::ThinVec;
33 use codemap::SpanUtils;
34 use comment::{contains_comment, remove_trailing_white_spaces, FindUncommented};
35 use expr::{rewrite_array, rewrite_call_inner};
36 use lists::{itemize_list, write_list, DefinitiveListTactic, ListFormatting, SeparatorPlace, SeparatorTactic};
37 use rewrite::{Rewrite, RewriteContext};
38 use shape::{Indent, Shape};
39 use utils::{format_visibility, mk_sp};
41 const FORCED_BRACKET_MACROS: &[&str] = &["vec!"];
43 // FIXME: use the enum from libsyntax?
44 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
51 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
52 pub enum MacroPosition {
60 fn opener(&self) -> &'static str {
62 MacroStyle::Parens => "(",
63 MacroStyle::Brackets => "[",
64 MacroStyle::Braces => "{",
76 impl Rewrite for MacroArg {
77 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
79 MacroArg::Expr(ref expr) => expr.rewrite(context, shape),
80 MacroArg::Ty(ref ty) => ty.rewrite(context, shape),
81 MacroArg::Pat(ref pat) => pat.rewrite(context, shape),
86 fn parse_macro_arg(parser: &mut Parser) -> Option<MacroArg> {
87 macro_rules! parse_macro_arg {
88 ($macro_arg: ident, $parser: ident) => {
89 let mut cloned_parser = (*parser).clone();
90 match cloned_parser.$parser() {
92 if parser.sess.span_diagnostic.has_errors() {
93 parser.sess.span_diagnostic.reset_err_count();
96 *parser = cloned_parser;
97 return Some(MacroArg::$macro_arg((*x).clone()));
102 parser.sess.span_diagnostic.reset_err_count();
108 parse_macro_arg!(Expr, parse_expr);
109 parse_macro_arg!(Ty, parse_ty);
110 parse_macro_arg!(Pat, parse_pat);
115 pub fn rewrite_macro(
117 extra_ident: Option<ast::Ident>,
118 context: &RewriteContext,
120 position: MacroPosition,
121 ) -> Option<String> {
122 let context = &mut context.clone();
123 context.inside_macro = true;
124 if context.config.use_try_shorthand() {
125 if let Some(expr) = convert_try_mac(mac, context) {
126 context.inside_macro = false;
127 return expr.rewrite(context, shape);
131 let original_style = macro_style(mac, context);
133 let macro_name = match extra_ident {
134 None => format!("{}!", mac.node.path),
136 if ident == symbol::keywords::Invalid.ident() {
137 format!("{}!", mac.node.path)
139 format!("{}! {}", mac.node.path, ident)
144 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
150 let ts: TokenStream = mac.node.stream();
151 if ts.is_empty() && !contains_comment(context.snippet(mac.span)) {
153 MacroStyle::Parens if position == MacroPosition::Item => {
154 Some(format!("{}();", macro_name))
156 MacroStyle::Parens => Some(format!("{}()", macro_name)),
157 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
158 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
162 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
163 let mut arg_vec = Vec::new();
164 let mut vec_with_semi = false;
165 let mut trailing_comma = false;
167 if MacroStyle::Braces != style {
169 match parse_macro_arg(&mut parser) {
170 Some(arg) => arg_vec.push(arg),
171 None => return Some(context.snippet(mac.span).to_owned()),
178 // Try to parse `vec![expr; expr]`
179 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
181 if parser.token != Token::Eof {
182 match parse_macro_arg(&mut parser) {
186 if parser.token == Token::Eof && arg_vec.len() == 2 {
187 vec_with_semi = true;
191 None => return Some(context.snippet(mac.span).to_owned()),
195 return Some(context.snippet(mac.span).to_owned());
197 _ => return Some(context.snippet(mac.span).to_owned()),
202 if parser.token == Token::Eof {
203 trailing_comma = true;
210 MacroStyle::Parens => {
211 // Format macro invocation as function call, forcing no trailing
212 // comma because not all macros support them.
216 &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..],
219 context.config.width_heuristics().fn_call_width,
221 ).map(|rw| match position {
222 MacroPosition::Item => format!("{};", rw),
226 MacroStyle::Brackets => {
227 let mac_shape = shape.offset_left(macro_name.len())?;
228 // Handle special case: `vec![expr; expr]`
230 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
236 let total_overhead = lbr.len() + rbr.len() + 6;
237 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
238 let lhs = arg_vec[0].rewrite(context, nested_shape)?;
239 let rhs = arg_vec[1].rewrite(context, nested_shape)?;
240 if !lhs.contains('\n') && !rhs.contains('\n')
241 && lhs.len() + rhs.len() + total_overhead <= shape.width
243 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
246 "{}{}\n{}{};\n{}{}\n{}{}",
249 nested_shape.indent.to_string(context.config),
251 nested_shape.indent.to_string(context.config),
253 shape.indent.to_string(context.config),
258 // If we are rewriting `vec!` macro or other special macros,
259 // then we can rewrite this as an usual array literal.
260 // Otherwise, we must preserve the original existence of trailing comma.
261 if FORCED_BRACKET_MACROS.contains(¯o_name.as_str()) {
262 context.inside_macro = false;
263 trailing_comma = false;
265 // Convert `MacroArg` into `ast::Expr`, as `rewrite_array` only accepts the latter.
269 .span_after(mac.span, original_style.opener()),
270 mac.span.hi() - BytePos(1),
272 let arg_vec = &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..];
273 let rewrite = rewrite_array(arg_vec, sp, context, mac_shape, trailing_comma)?;
275 Some(format!("{}{}", macro_name, rewrite))
278 MacroStyle::Braces => {
279 // Skip macro invocations with braces, for now.
280 indent_macro_snippet(context, context.snippet(mac.span), shape.indent)
285 pub fn rewrite_macro_def(
286 context: &RewriteContext,
291 vis: &ast::Visibility,
293 ) -> Option<String> {
294 let snippet = Some(remove_trailing_white_spaces(context.snippet(span)));
296 let mut parser = MacroParser::new(def.stream().into_trees());
297 let parsed_def = match parser.parse() {
299 None => return snippet,
302 let mut result = if def.legacy {
303 String::from("macro_rules!")
305 format!("{}macro", format_visibility(vis))
309 result += &ident.name.as_str();
311 let multi_branch_style = def.legacy || parsed_def.branches.len() != 1;
313 let mac_indent = if multi_branch_style {
315 indent.block_indent(context.config)
320 let mac_indent_str = mac_indent.to_string(context.config);
322 let branch_items = itemize_list(
324 parsed_def.branches.iter(),
327 |branch| branch.args_span.lo(),
328 |branch| branch.body.hi(),
330 let mut result = String::new();
332 // Only attempt to format function-like macros.
333 if branch.args_paren_kind != DelimToken::Paren {
334 // FIXME(#1539): implement for non-sugared macros.
338 let args = format_macro_args(branch.args.clone())?;
340 if multi_branch_style {
342 result += &mac_indent_str;
349 // The macro body is the most interesting part. It might end up as various
350 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
351 // parsed as regular Rust code (and note that these can be escaped using
352 // `$$`). We'll try and format like an AST node, but we'll substitute
353 // variables for new names with the same length first.
355 let old_body = context.snippet(branch.body).trim();
356 let (body_str, substs) = match replace_names(old_body) {
357 Some(result) => result,
358 None => return snippet,
361 let mut config = context.config.clone();
362 config.set().hide_parse_errors(true);
366 let has_block_body = old_body.starts_with('{');
368 let body_indent = if has_block_body {
371 // We'll hack the indent below, take this into account when formatting,
372 let body_indent = mac_indent.block_indent(&config);
373 let new_width = config.max_width() - body_indent.width();
374 config.set().max_width(new_width);
378 // First try to format as items, then as statements.
379 let new_body = match ::format_snippet(&body_str, &config) {
380 Some(new_body) => new_body,
381 None => match ::format_code_block(&body_str, &config) {
382 Some(new_body) => new_body,
387 // Indent the body since it is in a block.
388 let indent_str = body_indent.to_string(&config);
389 let mut new_body = new_body
392 .fold(String::new(), |mut s, l| {
399 // Undo our replacement of macro variables.
400 // FIXME: this could be *much* more efficient.
401 for (old, new) in &substs {
402 if old_body.find(new).is_some() {
404 "rewrite_macro_def: bailing matching variable: `{}` in `{}`",
409 new_body = new_body.replace(new, old);
413 result += new_body.trim();
414 } else if !new_body.is_empty() {
417 result += &mac_indent_str;
430 ).collect::<Vec<_>>();
432 let arm_shape = shape
433 .block_indent(context.config.tab_spaces())
434 .with_max_width(context.config);
436 let fmt = ListFormatting {
437 tactic: DefinitiveListTactic::Vertical,
439 trailing_separator: SeparatorTactic::Never,
440 separator_place: SeparatorPlace::Back,
442 ends_with_newline: false,
443 preserve_newline: true,
444 config: context.config,
447 result += write_list(&branch_items, &fmt)?.as_str();
449 if multi_branch_style {
450 result += &indent.to_string(context.config);
457 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
458 // aren't causing problems.
459 // This should also work for escaped `$` variables, where we leave earlier `$`s.
460 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
461 // Each substitution will require five or six extra bytes.
462 let mut result = String::with_capacity(input.len() + 64);
463 let mut substs = HashMap::new();
464 let mut dollar_count = 0;
465 let mut cur_name = String::new();
467 for c in input.chars() {
470 } else if dollar_count == 0 {
472 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
473 // Terminates a name following one or more dollars.
474 let mut new_name = String::new();
475 let mut old_name = String::new();
477 for _ in 0..(dollar_count - 1) {
482 new_name.push_str(&cur_name);
483 old_name.push_str(&cur_name);
485 result.push_str(&new_name);
486 substs.insert(old_name, new_name);
491 cur_name = String::new();
492 } else if c == '(' && cur_name.is_empty() {
493 // FIXME: Support macro def with repeat.
495 } else if c.is_alphanumeric() {
500 // FIXME: duplicate code
501 if !cur_name.is_empty() {
502 let mut new_name = String::new();
503 let mut old_name = String::new();
505 for _ in 0..(dollar_count - 1) {
510 new_name.push_str(&cur_name);
511 old_name.push_str(&cur_name);
513 result.push_str(&new_name);
514 substs.insert(old_name, new_name);
517 debug!("replace_names `{}` {:?}", result, substs);
519 Some((result, substs))
522 // This is a bit sketchy. The token rules probably need tweaking, but it works
523 // for some common cases. I hope the basic logic is sufficient. Note that the
524 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
525 // and `(`/`)` have special meaning.
527 // We always try and format on one line.
528 fn format_macro_args(toks: ThinTokenStream) -> Option<String> {
529 let mut result = String::with_capacity(128);
530 let mut insert_space = SpaceState::Never;
532 for tok in (toks.into(): TokenStream).trees() {
534 TokenTree::Token(_, t) => {
535 if !result.is_empty() && force_space_before(&t) {
536 insert_space = SpaceState::Always;
538 if force_no_space_before(&t) {
539 insert_space = SpaceState::Never;
541 match (insert_space, ident_like(&t)) {
542 (SpaceState::Always, _)
543 | (SpaceState::Punctuation, false)
544 | (SpaceState::Ident, true) => {
549 result.push_str(&pprust::token_to_string(&t));
550 insert_space = next_space(&t);
552 TokenTree::Delimited(_, d) => {
553 if let SpaceState::Always = insert_space {
556 let formatted = format_macro_args(d.tts)?;
558 DelimToken::Paren => {
559 result.push_str(&format!("({})", formatted));
560 insert_space = SpaceState::Always;
562 DelimToken::Bracket => {
563 result.push_str(&format!("[{}]", formatted));
564 insert_space = SpaceState::Always;
566 DelimToken::Brace => {
567 result.push_str(&format!(" {{ {} }}", formatted));
568 insert_space = SpaceState::Always;
570 DelimToken::NoDelim => {
571 result.push_str(&format!("{}", formatted));
572 insert_space = SpaceState::Always;
582 // We should insert a space if the next token is a:
583 #[derive(Copy, Clone)]
587 Ident, // Or ident/literal-like thing.
591 fn force_space_before(tok: &Token) -> bool {
610 | Token::Dollar => true,
611 Token::BinOp(bot) => bot != BinOpToken::Star,
616 fn force_no_space_before(tok: &Token) -> bool {
618 Token::Semi | Token::Comma | Token::Dot => true,
619 Token::BinOp(bot) => bot == BinOpToken::Star,
623 fn ident_like(tok: &Token) -> bool {
625 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
630 fn next_space(tok: &Token) -> SpaceState {
643 | Token::BinOp(_) => SpaceState::Punctuation,
648 | Token::OpenDelim(_)
649 | Token::CloseDelim(_)
650 | Token::Whitespace => SpaceState::Never,
652 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
654 _ => SpaceState::Always,
658 /// Tries to convert a macro use into a short hand try expression. Returns None
659 /// when the macro is not an instance of try! (or parsing the inner expression
661 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
662 if &format!("{}", mac.node.path)[..] == "try" {
663 let ts: TokenStream = mac.node.tts.clone().into();
664 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
667 id: ast::NodeId::new(0), // dummy value
668 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
669 span: mac.span, // incorrect span, but shouldn't matter too much
670 attrs: ThinVec::new(),
677 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
678 let snippet = context.snippet(mac.span);
679 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
680 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
681 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
683 if paren_pos < bracket_pos && paren_pos < brace_pos {
685 } else if bracket_pos < brace_pos {
692 /// Indent each line according to the specified `indent`.
717 fn indent_macro_snippet(
718 context: &RewriteContext,
721 ) -> Option<String> {
722 let mut lines = macro_str.lines();
723 let first_line = lines.next().map(|s| s.trim_right())?;
724 let mut trimmed_lines = Vec::with_capacity(16);
726 let min_prefix_space_width = lines
728 let prefix_space_width = if is_empty_line(line) {
731 Some(get_prefix_space_width(context, line))
733 trimmed_lines.push((line.trim(), prefix_space_width));
739 String::from(first_line) + "\n"
742 .map(|&(line, prefix_space_width)| match prefix_space_width {
743 Some(original_indent_width) => {
744 let new_indent_width = indent.width()
745 + original_indent_width
746 .checked_sub(min_prefix_space_width)
748 let new_indent = Indent::from_width(context.config, new_indent_width);
749 format!("{}{}", new_indent.to_string(context.config), line.trim())
751 None => String::new(),
758 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
763 '\t' => width += context.config.tab_spaces(),
770 fn is_empty_line(s: &str) -> bool {
771 s.is_empty() || s.chars().all(char::is_whitespace)
774 // A very simple parser that just parses a macros 2.0 definition into its branches.
775 // Currently we do not attempt to parse any further than that.
782 // (`(` ... `)` `=>` `{` ... `}`)*
783 fn parse(&mut self) -> Option<Macro> {
784 let mut branches = vec![];
785 while self.toks.look_ahead(1).is_some() {
786 branches.push(self.parse_branch()?);
789 Some(Macro { branches })
792 // `(` ... `)` `=>` `{` ... `}`
793 fn parse_branch(&mut self) -> Option<MacroBranch> {
794 let tok = self.toks.next()?;
795 let (args_span, args_paren_kind) = match tok {
796 TokenTree::Token(..) => return None,
797 TokenTree::Delimited(sp, ref d) => (sp, d.delim),
799 let args = tok.joint().into();
800 match self.toks.next()? {
801 TokenTree::Token(_, Token::FatArrow) => {}
804 let body = match self.toks.next()? {
805 TokenTree::Token(..) => return None,
806 TokenTree::Delimited(sp, _) => {
807 let data = sp.data();
808 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt)
811 if let Some(TokenTree::Token(_, Token::Semi)) = self.toks.look_ahead(0) {
823 // A parsed macros 2.0 macro definition.
825 branches: Vec<MacroBranch>,
828 // FIXME: it would be more efficient to use references to the token streams
829 // rather than clone them, if we can make the borrowing work out.
831 args_paren_kind: DelimToken,
833 args: ThinTokenStream,
840 use syntax::parse::{parse_stream_from_source_str, ParseSess};
841 use syntax::codemap::{FileName, FilePathMapping};
843 fn format_macro_args_str(s: &str) -> String {
844 let input = parse_stream_from_source_str(
845 FileName::Custom("stdin".to_owned()),
847 &ParseSess::new(FilePathMapping::empty()),
850 format_macro_args(input.into()).unwrap()
854 fn test_format_macro_args() {
855 assert_eq!(format_macro_args_str(""), "".to_owned());
856 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
858 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
859 "$m1: ident, $m2: ident, $x: ident".to_owned()
862 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
863 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
866 format_macro_args_str(
867 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
869 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()