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 rewrite::{Rewrite, RewriteContext};
37 use shape::{Indent, Shape};
38 use utils::{format_visibility, mk_sp};
40 const FORCED_BRACKET_MACROS: &[&str] = &["vec!"];
42 // FIXME: use the enum from libsyntax?
43 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
50 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
51 pub enum MacroPosition {
59 fn opener(&self) -> &'static str {
61 MacroStyle::Parens => "(",
62 MacroStyle::Brackets => "[",
63 MacroStyle::Braces => "{",
75 impl Rewrite for MacroArg {
76 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
78 MacroArg::Expr(ref expr) => expr.rewrite(context, shape),
79 MacroArg::Ty(ref ty) => ty.rewrite(context, shape),
80 MacroArg::Pat(ref pat) => pat.rewrite(context, shape),
85 fn parse_macro_arg(parser: &mut Parser) -> Option<MacroArg> {
86 macro_rules! parse_macro_arg {
87 ($macro_arg: ident, $parser: ident) => {
88 let mut cloned_parser = (*parser).clone();
89 match cloned_parser.$parser() {
91 if parser.sess.span_diagnostic.has_errors() {
92 parser.sess.span_diagnostic.reset_err_count();
95 *parser = cloned_parser;
96 return Some(MacroArg::$macro_arg((*x).clone()));
101 parser.sess.span_diagnostic.reset_err_count();
107 parse_macro_arg!(Expr, parse_expr);
108 parse_macro_arg!(Ty, parse_ty);
109 parse_macro_arg!(Pat, parse_pat);
114 pub fn rewrite_macro(
116 extra_ident: Option<ast::Ident>,
117 context: &RewriteContext,
119 position: MacroPosition,
120 ) -> Option<String> {
121 let context = &mut context.clone();
122 context.inside_macro = true;
123 if context.config.use_try_shorthand() {
124 if let Some(expr) = convert_try_mac(mac, context) {
125 context.inside_macro = false;
126 return expr.rewrite(context, shape);
130 let original_style = macro_style(mac, context);
132 let macro_name = match extra_ident {
133 None => format!("{}!", mac.node.path),
135 if ident == symbol::keywords::Invalid.ident() {
136 format!("{}!", mac.node.path)
138 format!("{}! {}", mac.node.path, ident)
143 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
149 let ts: TokenStream = mac.node.stream();
150 if ts.is_empty() && !contains_comment(context.snippet(mac.span)) {
152 MacroStyle::Parens if position == MacroPosition::Item => {
153 Some(format!("{}();", macro_name))
155 MacroStyle::Parens => Some(format!("{}()", macro_name)),
156 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
157 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
161 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
162 let mut arg_vec = Vec::new();
163 let mut vec_with_semi = false;
164 let mut trailing_comma = false;
166 if MacroStyle::Braces != style {
168 match parse_macro_arg(&mut parser) {
169 Some(arg) => arg_vec.push(arg),
170 None => return Some(context.snippet(mac.span).to_owned()),
177 // Try to parse `vec![expr; expr]`
178 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
180 if parser.token != Token::Eof {
181 match parse_macro_arg(&mut parser) {
185 if parser.token == Token::Eof && arg_vec.len() == 2 {
186 vec_with_semi = true;
190 None => return Some(context.snippet(mac.span).to_owned()),
194 return Some(context.snippet(mac.span).to_owned());
196 _ => return Some(context.snippet(mac.span).to_owned()),
201 if parser.token == Token::Eof {
202 trailing_comma = true;
209 MacroStyle::Parens => {
210 // Format macro invocation as function call, forcing no trailing
211 // comma because not all macros support them.
215 &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..],
218 context.config.width_heuristics().fn_call_width,
220 ).map(|rw| match position {
221 MacroPosition::Item => format!("{};", rw),
225 MacroStyle::Brackets => {
226 let mac_shape = shape.offset_left(macro_name.len())?;
227 // Handle special case: `vec![expr; expr]`
229 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
235 let total_overhead = lbr.len() + rbr.len() + 6;
236 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
237 let lhs = arg_vec[0].rewrite(context, nested_shape)?;
238 let rhs = arg_vec[1].rewrite(context, nested_shape)?;
239 if !lhs.contains('\n') && !rhs.contains('\n')
240 && lhs.len() + rhs.len() + total_overhead <= shape.width
242 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
245 "{}{}\n{}{};\n{}{}\n{}{}",
248 nested_shape.indent.to_string(context.config),
250 nested_shape.indent.to_string(context.config),
252 shape.indent.to_string(context.config),
257 // If we are rewriting `vec!` macro or other special macros,
258 // then we can rewrite this as an usual array literal.
259 // Otherwise, we must preserve the original existence of trailing comma.
260 if FORCED_BRACKET_MACROS.contains(¯o_name.as_str()) {
261 context.inside_macro = false;
262 trailing_comma = false;
264 // Convert `MacroArg` into `ast::Expr`, as `rewrite_array` only accepts the latter.
268 .span_after(mac.span, original_style.opener()),
269 mac.span.hi() - BytePos(1),
271 let arg_vec = &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..];
272 let rewrite = rewrite_array(arg_vec, sp, context, mac_shape, trailing_comma)?;
274 Some(format!("{}{}", macro_name, rewrite))
277 MacroStyle::Braces => {
278 // Skip macro invocations with braces, for now.
279 indent_macro_snippet(context, context.snippet(mac.span), shape.indent)
284 pub fn rewrite_macro_def(
285 context: &RewriteContext,
289 vis: &ast::Visibility,
291 ) -> Option<String> {
292 let snippet = Some(remove_trailing_white_spaces(context.snippet(span)));
294 let mut parser = MacroParser::new(def.stream().into_trees());
295 let parsed_def = match parser.parse() {
297 None => return snippet,
300 let mut result = if def.legacy {
301 String::from("macro_rules!")
303 format!("{}macro", format_visibility(vis))
307 result += &ident.name.as_str();
310 let mac_indent = indent.block_indent(context.config);
311 let mac_indent_str = mac_indent.to_string(context.config);
313 for branch in parsed_def.branches {
314 // Only attempt to format function-like macros.
315 if branch.args_paren_kind != DelimToken::Paren {
316 // FIXME(#1539): implement for non-sugared macros.
321 result += &mac_indent_str;
323 result += &format_macro_args(branch.args)?;
324 result += ") => {\n";
326 // The macro body is the most interesting part. It might end up as various
327 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
328 // parsed as regular Rust code (and note that these can be escaped using
329 // `$$`). We'll try and format like an AST node, but we'll substitute
330 // variables for new names with the same length first.
332 let old_body = context.snippet(branch.body).trim();
333 let (body_str, substs) = match replace_names(old_body) {
334 Some(result) => result,
335 None => return snippet,
338 // We'll hack the indent below, take this into account when formatting,
339 let mut config = context.config.clone();
340 let body_indent = mac_indent.block_indent(&config);
341 let new_width = config.max_width() - body_indent.width();
342 config.set().max_width(new_width);
343 config.set().hide_parse_errors(true);
345 // First try to format as items, then as statements.
346 let new_body = match ::format_snippet(&body_str, &config) {
347 Some(new_body) => new_body,
348 None => match ::format_code_block(&body_str, &config) {
349 Some(new_body) => new_body,
350 None => return snippet,
354 // Indent the body since it is in a block.
355 let indent_str = body_indent.to_string(&config);
356 let mut new_body = new_body
359 .fold(String::new(), |mut s, l| {
366 // Undo our replacement of macro variables.
367 // FIXME: this could be *much* more efficient.
368 for (old, new) in &substs {
369 if old_body.find(new).is_some() {
371 "rewrite_macro_def: bailing matching variable: `{}` in `{}`",
376 new_body = new_body.replace(new, old);
381 result += &mac_indent_str;
389 result += &indent.to_string(context.config);
395 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
396 // aren't causing problems.
397 // This should also work for escaped `$` variables, where we leave earlier `$`s.
398 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
399 // Each substitution will require five or six extra bytes.
400 let mut result = String::with_capacity(input.len() + 64);
401 let mut substs = HashMap::new();
402 let mut dollar_count = 0;
403 let mut cur_name = String::new();
405 for c in input.chars() {
408 } else if dollar_count == 0 {
410 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
411 // Terminates a name following one or more dollars.
412 let mut new_name = String::new();
413 let mut old_name = String::new();
415 for _ in 0..(dollar_count - 1) {
420 new_name.push_str(&cur_name);
421 old_name.push_str(&cur_name);
423 result.push_str(&new_name);
424 substs.insert(old_name, new_name);
429 cur_name = String::new();
430 } else if c == '(' && cur_name.is_empty() {
431 // FIXME: Support macro def with repeat.
433 } else if c.is_alphanumeric() {
438 // FIXME: duplicate code
439 if !cur_name.is_empty() {
440 let mut new_name = String::new();
441 let mut old_name = String::new();
443 for _ in 0..(dollar_count - 1) {
448 new_name.push_str(&cur_name);
449 old_name.push_str(&cur_name);
451 result.push_str(&new_name);
452 substs.insert(old_name, new_name);
455 debug!("replace_names `{}` {:?}", result, substs);
457 Some((result, substs))
460 // This is a bit sketchy. The token rules probably need tweaking, but it works
461 // for some common cases. I hope the basic logic is sufficient. Note that the
462 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
463 // and `(`/`)` have special meaning.
465 // We always try and format on one line.
466 fn format_macro_args(toks: ThinTokenStream) -> Option<String> {
467 let mut result = String::with_capacity(128);
468 let mut insert_space = SpaceState::Never;
470 for tok in (toks.into(): TokenStream).trees() {
472 TokenTree::Token(_, t) => {
473 if !result.is_empty() && force_space_before(&t) {
474 insert_space = SpaceState::Always;
476 if force_no_space_before(&t) {
477 insert_space = SpaceState::Never;
479 match (insert_space, ident_like(&t)) {
480 (SpaceState::Always, _)
481 | (SpaceState::Punctuation, false)
482 | (SpaceState::Ident, true) => {
487 result.push_str(&pprust::token_to_string(&t));
488 insert_space = next_space(&t);
490 TokenTree::Delimited(_, d) => {
491 if let SpaceState::Always = insert_space {
494 let formatted = format_macro_args(d.tts)?;
496 DelimToken::Paren => {
497 result.push_str(&format!("({})", formatted));
498 insert_space = SpaceState::Always;
500 DelimToken::Bracket => {
501 result.push_str(&format!("[{}]", formatted));
502 insert_space = SpaceState::Always;
504 DelimToken::Brace => {
505 result.push_str(&format!(" {{ {} }}", formatted));
506 insert_space = SpaceState::Always;
508 DelimToken::NoDelim => {
509 result.push_str(&format!("{}", formatted));
510 insert_space = SpaceState::Always;
520 // We should insert a space if the next token is a:
521 #[derive(Copy, Clone)]
525 Ident, // Or ident/literal-like thing.
529 fn force_space_before(tok: &Token) -> bool {
548 | Token::Dollar => true,
549 Token::BinOp(bot) => bot != BinOpToken::Star,
554 fn force_no_space_before(tok: &Token) -> bool {
556 Token::Semi | Token::Comma | Token::Dot => true,
557 Token::BinOp(bot) => bot == BinOpToken::Star,
561 fn ident_like(tok: &Token) -> bool {
563 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
568 fn next_space(tok: &Token) -> SpaceState {
581 | Token::BinOp(_) => SpaceState::Punctuation,
586 | Token::OpenDelim(_)
587 | Token::CloseDelim(_)
588 | Token::Whitespace => SpaceState::Never,
590 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
592 _ => SpaceState::Always,
596 /// Tries to convert a macro use into a short hand try expression. Returns None
597 /// when the macro is not an instance of try! (or parsing the inner expression
599 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
600 if &format!("{}", mac.node.path)[..] == "try" {
601 let ts: TokenStream = mac.node.tts.clone().into();
602 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
605 id: ast::NodeId::new(0), // dummy value
606 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
607 span: mac.span, // incorrect span, but shouldn't matter too much
608 attrs: ThinVec::new(),
615 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
616 let snippet = context.snippet(mac.span);
617 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
618 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
619 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
621 if paren_pos < bracket_pos && paren_pos < brace_pos {
623 } else if bracket_pos < brace_pos {
630 /// 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 (args_paren_kind, args) = match self.toks.next()? {
733 TokenTree::Token(..) => return None,
734 TokenTree::Delimited(_, ref d) => (d.delim, d.tts.clone()),
736 match self.toks.next()? {
737 TokenTree::Token(_, Token::FatArrow) => {}
740 let body = match self.toks.next()? {
741 TokenTree::Token(..) => return None,
742 TokenTree::Delimited(sp, _) => {
743 let data = sp.data();
744 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt)
747 if let Some(TokenTree::Token(_, Token::Semi)) = self.toks.look_ahead(0) {
758 // A parsed macros 2.0 macro definition.
760 branches: Vec<MacroBranch>,
763 // FIXME: it would be more efficient to use references to the token streams
764 // rather than clone them, if we can make the borrowing work out.
766 args: ThinTokenStream,
767 args_paren_kind: DelimToken,
774 use syntax::parse::{parse_stream_from_source_str, ParseSess};
775 use syntax::codemap::{FileName, FilePathMapping};
777 fn format_macro_args_str(s: &str) -> String {
778 let input = parse_stream_from_source_str(
779 FileName::Custom("stdin".to_owned()),
781 &ParseSess::new(FilePathMapping::empty()),
784 format_macro_args(input.into()).unwrap()
788 fn test_format_macro_args() {
789 assert_eq!(format_macro_args_str(""), "".to_owned());
790 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
792 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
793 "$m1: ident, $m2: ident, $x: ident".to_owned()
796 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
797 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
800 format_macro_args_str(
801 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
803 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()