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,
38 use rewrite::{Rewrite, RewriteContext};
39 use shape::{Indent, Shape};
40 use utils::{format_visibility, mk_sp};
42 const FORCED_BRACKET_MACROS: &[&str] = &["vec!"];
44 // FIXME: use the enum from libsyntax?
45 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
52 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
53 pub enum MacroPosition {
61 fn opener(&self) -> &'static str {
63 MacroStyle::Parens => "(",
64 MacroStyle::Brackets => "[",
65 MacroStyle::Braces => "{",
77 impl Rewrite for MacroArg {
78 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
80 MacroArg::Expr(ref expr) => expr.rewrite(context, shape),
81 MacroArg::Ty(ref ty) => ty.rewrite(context, shape),
82 MacroArg::Pat(ref pat) => pat.rewrite(context, shape),
87 fn parse_macro_arg(parser: &mut Parser) -> Option<MacroArg> {
88 macro_rules! parse_macro_arg {
89 ($macro_arg: ident, $parser: ident) => {
90 let mut cloned_parser = (*parser).clone();
91 match cloned_parser.$parser() {
93 if parser.sess.span_diagnostic.has_errors() {
94 parser.sess.span_diagnostic.reset_err_count();
97 *parser = cloned_parser;
98 return Some(MacroArg::$macro_arg((*x).clone()));
103 parser.sess.span_diagnostic.reset_err_count();
109 parse_macro_arg!(Expr, parse_expr);
110 parse_macro_arg!(Ty, parse_ty);
111 parse_macro_arg!(Pat, parse_pat);
116 pub fn rewrite_macro(
118 extra_ident: Option<ast::Ident>,
119 context: &RewriteContext,
121 position: MacroPosition,
122 ) -> Option<String> {
123 let context = &mut context.clone();
124 context.inside_macro = true;
125 if context.config.use_try_shorthand() {
126 if let Some(expr) = convert_try_mac(mac, context) {
127 context.inside_macro = false;
128 return expr.rewrite(context, shape);
132 let original_style = macro_style(mac, context);
134 let macro_name = match extra_ident {
135 None => format!("{}!", mac.node.path),
137 if ident == symbol::keywords::Invalid.ident() {
138 format!("{}!", mac.node.path)
140 format!("{}! {}", mac.node.path, ident)
145 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
151 let ts: TokenStream = mac.node.stream();
152 if ts.is_empty() && !contains_comment(context.snippet(mac.span)) {
154 MacroStyle::Parens if position == MacroPosition::Item => {
155 Some(format!("{}();", macro_name))
157 MacroStyle::Parens => Some(format!("{}()", macro_name)),
158 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
159 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
163 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
164 let mut arg_vec = Vec::new();
165 let mut vec_with_semi = false;
166 let mut trailing_comma = false;
168 if MacroStyle::Braces != style {
170 match parse_macro_arg(&mut parser) {
171 Some(arg) => arg_vec.push(arg),
172 None => return Some(context.snippet(mac.span).to_owned()),
179 // Try to parse `vec![expr; expr]`
180 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
182 if parser.token != Token::Eof {
183 match parse_macro_arg(&mut parser) {
187 if parser.token == Token::Eof && arg_vec.len() == 2 {
188 vec_with_semi = true;
192 None => return Some(context.snippet(mac.span).to_owned()),
196 return Some(context.snippet(mac.span).to_owned());
198 _ => return Some(context.snippet(mac.span).to_owned()),
203 if parser.token == Token::Eof {
204 trailing_comma = true;
211 MacroStyle::Parens => {
212 // Format macro invocation as function call, forcing no trailing
213 // comma because not all macros support them.
217 &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..],
220 context.config.width_heuristics().fn_call_width,
222 ).map(|rw| match position {
223 MacroPosition::Item => format!("{};", rw),
227 MacroStyle::Brackets => {
228 let mac_shape = shape.offset_left(macro_name.len())?;
229 // Handle special case: `vec![expr; expr]`
231 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
237 let total_overhead = lbr.len() + rbr.len() + 6;
238 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
239 let lhs = arg_vec[0].rewrite(context, nested_shape)?;
240 let rhs = arg_vec[1].rewrite(context, nested_shape)?;
241 if !lhs.contains('\n') && !rhs.contains('\n')
242 && lhs.len() + rhs.len() + total_overhead <= shape.width
244 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
247 "{}{}\n{}{};\n{}{}\n{}{}",
250 nested_shape.indent.to_string(context.config),
252 nested_shape.indent.to_string(context.config),
254 shape.indent.to_string(context.config),
259 // If we are rewriting `vec!` macro or other special macros,
260 // then we can rewrite this as an usual array literal.
261 // Otherwise, we must preserve the original existence of trailing comma.
262 if FORCED_BRACKET_MACROS.contains(¯o_name.as_str()) {
263 context.inside_macro = false;
264 trailing_comma = false;
266 // Convert `MacroArg` into `ast::Expr`, as `rewrite_array` only accepts the latter.
270 .span_after(mac.span, original_style.opener()),
271 mac.span.hi() - BytePos(1),
273 let arg_vec = &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..];
274 let rewrite = rewrite_array(arg_vec, sp, context, mac_shape, trailing_comma)?;
276 Some(format!("{}{}", macro_name, rewrite))
279 MacroStyle::Braces => {
280 // Skip macro invocations with braces, for now.
281 indent_macro_snippet(context, context.snippet(mac.span), shape.indent)
286 pub fn rewrite_macro_def(
287 context: &RewriteContext,
292 vis: &ast::Visibility,
294 ) -> Option<String> {
295 let snippet = Some(remove_trailing_white_spaces(context.snippet(span)));
297 let mut parser = MacroParser::new(def.stream().into_trees());
298 let parsed_def = match parser.parse() {
300 None => return snippet,
303 let mut result = if def.legacy {
304 String::from("macro_rules!")
306 format!("{}macro", format_visibility(vis))
310 result += &ident.name.as_str();
312 let multi_branch_style = def.legacy || parsed_def.branches.len() != 1;
314 let arm_shape = if multi_branch_style {
316 .block_indent(context.config.tab_spaces())
317 .with_max_width(context.config)
322 let branch_items = itemize_list(
324 parsed_def.branches.iter(),
327 |branch| branch.span.lo(),
328 |branch| branch.span.hi(),
329 |branch| branch.rewrite(context, arm_shape, multi_branch_style),
330 context.codemap.span_after(span, "{"),
333 ).collect::<Vec<_>>();
335 let fmt = ListFormatting {
336 tactic: DefinitiveListTactic::Vertical,
337 separator: if def.legacy { ";" } else { "" },
338 trailing_separator: SeparatorTactic::Always,
339 separator_place: SeparatorPlace::Back,
341 ends_with_newline: true,
342 preserve_newline: true,
343 config: context.config,
346 if multi_branch_style {
348 result += &arm_shape.indent.to_string(context.config);
351 result += write_list(&branch_items, &fmt)?.as_str();
353 if multi_branch_style {
355 result += &indent.to_string(context.config);
362 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
363 // aren't causing problems.
364 // This should also work for escaped `$` variables, where we leave earlier `$`s.
365 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
366 // Each substitution will require five or six extra bytes.
367 let mut result = String::with_capacity(input.len() + 64);
368 let mut substs = HashMap::new();
369 let mut dollar_count = 0;
370 let mut cur_name = String::new();
372 for c in input.chars() {
375 } else if dollar_count == 0 {
377 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
378 // Terminates a name following one or more dollars.
379 let mut new_name = String::new();
380 let mut old_name = String::new();
382 for _ in 0..(dollar_count - 1) {
387 new_name.push_str(&cur_name);
388 old_name.push_str(&cur_name);
390 result.push_str(&new_name);
391 substs.insert(old_name, new_name);
396 cur_name = String::new();
397 } else if c == '(' && cur_name.is_empty() {
398 // FIXME: Support macro def with repeat.
400 } else if c.is_alphanumeric() {
405 // FIXME: duplicate code
406 if !cur_name.is_empty() {
407 let mut new_name = String::new();
408 let mut old_name = String::new();
410 for _ in 0..(dollar_count - 1) {
415 new_name.push_str(&cur_name);
416 old_name.push_str(&cur_name);
418 result.push_str(&new_name);
419 substs.insert(old_name, new_name);
422 debug!("replace_names `{}` {:?}", result, substs);
424 Some((result, substs))
427 // This is a bit sketchy. The token rules probably need tweaking, but it works
428 // for some common cases. I hope the basic logic is sufficient. Note that the
429 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
430 // and `(`/`)` have special meaning.
432 // We always try and format on one line.
433 fn format_macro_args(toks: ThinTokenStream) -> Option<String> {
434 let mut result = String::with_capacity(128);
435 let mut insert_space = SpaceState::Never;
437 for tok in (toks.into(): TokenStream).trees() {
439 TokenTree::Token(_, t) => {
440 if !result.is_empty() && force_space_before(&t) {
441 insert_space = SpaceState::Always;
443 if force_no_space_before(&t) {
444 insert_space = SpaceState::Never;
446 match (insert_space, ident_like(&t)) {
447 (SpaceState::Always, _)
448 | (SpaceState::Punctuation, false)
449 | (SpaceState::Ident, true) => {
454 result.push_str(&pprust::token_to_string(&t));
455 insert_space = next_space(&t);
457 TokenTree::Delimited(_, d) => {
458 if let SpaceState::Always = insert_space {
461 let formatted = format_macro_args(d.tts)?;
463 DelimToken::Paren => {
464 result.push_str(&format!("({})", formatted));
465 insert_space = SpaceState::Always;
467 DelimToken::Bracket => {
468 result.push_str(&format!("[{}]", formatted));
469 insert_space = SpaceState::Always;
471 DelimToken::Brace => {
472 result.push_str(&format!(" {{ {} }}", formatted));
473 insert_space = SpaceState::Always;
475 DelimToken::NoDelim => {
476 result.push_str(&format!("{}", formatted));
477 insert_space = SpaceState::Always;
487 // We should insert a space if the next token is a:
488 #[derive(Copy, Clone)]
492 Ident, // Or ident/literal-like thing.
496 fn force_space_before(tok: &Token) -> bool {
515 | Token::Dollar => true,
516 Token::BinOp(bot) => bot != BinOpToken::Star,
521 fn force_no_space_before(tok: &Token) -> bool {
523 Token::Semi | Token::Comma | Token::Dot => true,
524 Token::BinOp(bot) => bot == BinOpToken::Star,
528 fn ident_like(tok: &Token) -> bool {
530 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
535 fn next_space(tok: &Token) -> SpaceState {
548 | Token::BinOp(_) => SpaceState::Punctuation,
553 | Token::OpenDelim(_)
554 | Token::CloseDelim(_)
555 | Token::Whitespace => SpaceState::Never,
557 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
559 _ => SpaceState::Always,
563 /// Tries to convert a macro use into a short hand try expression. Returns None
564 /// when the macro is not an instance of try! (or parsing the inner expression
566 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
567 if &format!("{}", mac.node.path)[..] == "try" {
568 let ts: TokenStream = mac.node.tts.clone().into();
569 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
572 id: ast::NodeId::new(0), // dummy value
573 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
574 span: mac.span, // incorrect span, but shouldn't matter too much
575 attrs: ThinVec::new(),
582 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
583 let snippet = context.snippet(mac.span);
584 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
585 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
586 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
588 if paren_pos < bracket_pos && paren_pos < brace_pos {
590 } else if bracket_pos < brace_pos {
597 /// Indent each line according to the specified `indent`.
622 fn indent_macro_snippet(
623 context: &RewriteContext,
626 ) -> Option<String> {
627 let mut lines = macro_str.lines();
628 let first_line = lines.next().map(|s| s.trim_right())?;
629 let mut trimmed_lines = Vec::with_capacity(16);
631 let min_prefix_space_width = lines
633 let prefix_space_width = if is_empty_line(line) {
636 Some(get_prefix_space_width(context, line))
638 trimmed_lines.push((line.trim(), prefix_space_width));
644 String::from(first_line) + "\n"
647 .map(|&(line, prefix_space_width)| match prefix_space_width {
648 Some(original_indent_width) => {
649 let new_indent_width = indent.width()
650 + original_indent_width
651 .checked_sub(min_prefix_space_width)
653 let new_indent = Indent::from_width(context.config, new_indent_width);
654 format!("{}{}", new_indent.to_string(context.config), line.trim())
656 None => String::new(),
663 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
668 '\t' => width += context.config.tab_spaces(),
675 fn is_empty_line(s: &str) -> bool {
676 s.is_empty() || s.chars().all(char::is_whitespace)
679 // A very simple parser that just parses a macros 2.0 definition into its branches.
680 // Currently we do not attempt to parse any further than that.
687 // (`(` ... `)` `=>` `{` ... `}`)*
688 fn parse(&mut self) -> Option<Macro> {
689 let mut branches = vec![];
690 while self.toks.look_ahead(1).is_some() {
691 branches.push(self.parse_branch()?);
694 Some(Macro { branches })
697 // `(` ... `)` `=>` `{` ... `}`
698 fn parse_branch(&mut self) -> Option<MacroBranch> {
699 let tok = self.toks.next()?;
700 let (lo, args_paren_kind) = match tok {
701 TokenTree::Token(..) => return None,
702 TokenTree::Delimited(sp, ref d) => (sp.lo(), d.delim),
704 let args = tok.joint().into();
705 match self.toks.next()? {
706 TokenTree::Token(_, Token::FatArrow) => {}
709 let (mut hi, body) = match self.toks.next()? {
710 TokenTree::Token(..) => return None,
711 TokenTree::Delimited(sp, _) => {
712 let data = sp.data();
715 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt),
719 if let Some(TokenTree::Token(sp, Token::Semi)) = self.toks.look_ahead(0) {
732 // A parsed macros 2.0 macro definition.
734 branches: Vec<MacroBranch>,
737 // FIXME: it would be more efficient to use references to the token streams
738 // rather than clone them, if we can make the borrowing work out.
741 args_paren_kind: DelimToken,
742 args: ThinTokenStream,
749 context: &RewriteContext,
751 multi_branch_style: bool,
752 ) -> Option<String> {
753 // Only attempt to format function-like macros.
754 if self.args_paren_kind != DelimToken::Paren {
755 // FIXME(#1539): implement for non-sugared macros.
759 let mut result = format_macro_args(self.args.clone())?;
761 if multi_branch_style {
765 // The macro body is the most interesting part. It might end up as various
766 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
767 // parsed as regular Rust code (and note that these can be escaped using
768 // `$$`). We'll try and format like an AST node, but we'll substitute
769 // variables for new names with the same length first.
771 let old_body = context.snippet(self.body).trim();
772 let (body_str, substs) = replace_names(old_body)?;
774 let mut config = context.config.clone();
775 config.set().hide_parse_errors(true);
779 let has_block_body = old_body.starts_with('{');
781 let body_indent = if has_block_body {
784 // We'll hack the indent below, take this into account when formatting,
785 let body_indent = shape.indent.block_indent(&config);
786 let new_width = config.max_width() - body_indent.width();
787 config.set().max_width(new_width);
791 // First try to format as items, then as statements.
792 let new_body = match ::format_snippet(&body_str, &config) {
793 Some(new_body) => new_body,
794 None => match ::format_code_block(&body_str, &config) {
795 Some(new_body) => new_body,
800 // Indent the body since it is in a block.
801 let indent_str = body_indent.to_string(&config);
802 let mut new_body = new_body
805 .fold(String::new(), |mut s, l| {
812 // Undo our replacement of macro variables.
813 // FIXME: this could be *much* more efficient.
814 for (old, new) in &substs {
815 if old_body.find(new).is_some() {
816 debug!("rewrite_macro_def: bailing matching variable: `{}`", new);
819 new_body = new_body.replace(new, old);
823 result += new_body.trim();
824 } else if !new_body.is_empty() {
827 result += &shape.indent.to_string(&config);
839 use syntax::parse::{parse_stream_from_source_str, ParseSess};
840 use syntax::codemap::{FileName, FilePathMapping};
842 fn format_macro_args_str(s: &str) -> String {
843 let input = parse_stream_from_source_str(
844 FileName::Custom("stdin".to_owned()),
846 &ParseSess::new(FilePathMapping::empty()),
849 format_macro_args(input.into()).unwrap()
853 fn test_format_macro_args() {
854 assert_eq!(format_macro_args_str(""), "".to_owned());
855 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
857 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
858 "$m1: ident, $m2: ident, $x: ident".to_owned()
861 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
862 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
865 format_macro_args_str(
866 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
868 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()