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();
309 let multi_branch_style = def.legacy || parsed_def.branches.len() != 1;
311 let mac_indent = if multi_branch_style {
313 indent.block_indent(context.config)
318 let mac_indent_str = mac_indent.to_string(context.config);
320 for branch in parsed_def.branches {
321 // Only attempt to format function-like macros.
322 if branch.args_paren_kind != DelimToken::Paren {
323 // FIXME(#1539): implement for non-sugared macros.
327 let args = format!("({})", format_macro_args(branch.args)?);
329 if multi_branch_style {
331 result += &mac_indent_str;
338 // The macro body is the most interesting part. It might end up as various
339 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
340 // parsed as regular Rust code (and note that these can be escaped using
341 // `$$`). We'll try and format like an AST node, but we'll substitute
342 // variables for new names with the same length first.
344 let old_body = context.snippet(branch.body).trim();
345 let (body_str, substs) = match replace_names(old_body) {
346 Some(result) => result,
347 None => return snippet,
350 let mut config = context.config.clone();
351 config.set().hide_parse_errors(true);
355 let has_block_body = old_body.starts_with("{");
357 let body_indent = if has_block_body {
360 // We'll hack the indent below, take this into account when formatting,
361 let body_indent = mac_indent.block_indent(&config);
362 let new_width = config.max_width() - body_indent.width();
363 config.set().max_width(new_width);
367 // First try to format as items, then as statements.
368 let new_body = match ::format_snippet(&body_str, &config) {
369 Some(new_body) => new_body,
370 None => match ::format_code_block(&body_str, &config) {
371 Some(new_body) => new_body,
372 None => return snippet,
376 // Indent the body since it is in a block.
377 let indent_str = body_indent.to_string(&config);
378 let mut new_body = new_body
381 .fold(String::new(), |mut s, l| {
388 // Undo our replacement of macro variables.
389 // FIXME: this could be *much* more efficient.
390 for (old, new) in &substs {
391 if old_body.find(new).is_some() {
393 "rewrite_macro_def: bailing matching variable: `{}` in `{}`",
398 new_body = new_body.replace(new, old);
402 result += new_body.trim();
406 result += &mac_indent_str;
416 if multi_branch_style {
417 result += &indent.to_string(context.config);
424 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
425 // aren't causing problems.
426 // This should also work for escaped `$` variables, where we leave earlier `$`s.
427 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
428 // Each substitution will require five or six extra bytes.
429 let mut result = String::with_capacity(input.len() + 64);
430 let mut substs = HashMap::new();
431 let mut dollar_count = 0;
432 let mut cur_name = String::new();
434 for c in input.chars() {
437 } else if dollar_count == 0 {
439 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
440 // Terminates a name following one or more dollars.
441 let mut new_name = String::new();
442 let mut old_name = String::new();
444 for _ in 0..(dollar_count - 1) {
449 new_name.push_str(&cur_name);
450 old_name.push_str(&cur_name);
452 result.push_str(&new_name);
453 substs.insert(old_name, new_name);
458 cur_name = String::new();
459 } else if c == '(' && cur_name.is_empty() {
460 // FIXME: Support macro def with repeat.
462 } else if c.is_alphanumeric() {
467 // FIXME: duplicate code
468 if !cur_name.is_empty() {
469 let mut new_name = String::new();
470 let mut old_name = String::new();
472 for _ in 0..(dollar_count - 1) {
477 new_name.push_str(&cur_name);
478 old_name.push_str(&cur_name);
480 result.push_str(&new_name);
481 substs.insert(old_name, new_name);
484 debug!("replace_names `{}` {:?}", result, substs);
486 Some((result, substs))
489 // This is a bit sketchy. The token rules probably need tweaking, but it works
490 // for some common cases. I hope the basic logic is sufficient. Note that the
491 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
492 // and `(`/`)` have special meaning.
494 // We always try and format on one line.
495 fn format_macro_args(toks: ThinTokenStream) -> Option<String> {
496 let mut result = String::with_capacity(128);
497 let mut insert_space = SpaceState::Never;
499 for tok in (toks.into(): TokenStream).trees() {
501 TokenTree::Token(_, t) => {
502 if !result.is_empty() && force_space_before(&t) {
503 insert_space = SpaceState::Always;
505 if force_no_space_before(&t) {
506 insert_space = SpaceState::Never;
508 match (insert_space, ident_like(&t)) {
509 (SpaceState::Always, _)
510 | (SpaceState::Punctuation, false)
511 | (SpaceState::Ident, true) => {
516 result.push_str(&pprust::token_to_string(&t));
517 insert_space = next_space(&t);
519 TokenTree::Delimited(_, d) => {
520 if let SpaceState::Always = insert_space {
523 let formatted = format_macro_args(d.tts)?;
525 DelimToken::Paren => {
526 result.push_str(&format!("({})", formatted));
527 insert_space = SpaceState::Always;
529 DelimToken::Bracket => {
530 result.push_str(&format!("[{}]", formatted));
531 insert_space = SpaceState::Always;
533 DelimToken::Brace => {
534 result.push_str(&format!(" {{ {} }}", formatted));
535 insert_space = SpaceState::Always;
537 DelimToken::NoDelim => {
538 result.push_str(&format!("{}", formatted));
539 insert_space = SpaceState::Always;
549 // We should insert a space if the next token is a:
550 #[derive(Copy, Clone)]
554 Ident, // Or ident/literal-like thing.
558 fn force_space_before(tok: &Token) -> bool {
577 | Token::Dollar => true,
578 Token::BinOp(bot) => bot != BinOpToken::Star,
583 fn force_no_space_before(tok: &Token) -> bool {
585 Token::Semi | Token::Comma | Token::Dot => true,
586 Token::BinOp(bot) => bot == BinOpToken::Star,
590 fn ident_like(tok: &Token) -> bool {
592 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
597 fn next_space(tok: &Token) -> SpaceState {
610 | Token::BinOp(_) => SpaceState::Punctuation,
615 | Token::OpenDelim(_)
616 | Token::CloseDelim(_)
617 | Token::Whitespace => SpaceState::Never,
619 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
621 _ => SpaceState::Always,
625 /// Tries to convert a macro use into a short hand try expression. Returns None
626 /// when the macro is not an instance of try! (or parsing the inner expression
628 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
629 if &format!("{}", mac.node.path)[..] == "try" {
630 let ts: TokenStream = mac.node.tts.clone().into();
631 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
634 id: ast::NodeId::new(0), // dummy value
635 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
636 span: mac.span, // incorrect span, but shouldn't matter too much
637 attrs: ThinVec::new(),
644 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
645 let snippet = context.snippet(mac.span);
646 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
647 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
648 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
650 if paren_pos < bracket_pos && paren_pos < brace_pos {
652 } else if bracket_pos < brace_pos {
659 /// Indent each line according to the specified `indent`.
684 fn indent_macro_snippet(
685 context: &RewriteContext,
688 ) -> Option<String> {
689 let mut lines = macro_str.lines();
690 let first_line = lines.next().map(|s| s.trim_right())?;
691 let mut trimmed_lines = Vec::with_capacity(16);
693 let min_prefix_space_width = lines
695 let prefix_space_width = if is_empty_line(line) {
698 Some(get_prefix_space_width(context, line))
700 trimmed_lines.push((line.trim(), prefix_space_width));
706 String::from(first_line) + "\n"
709 .map(|&(line, prefix_space_width)| match prefix_space_width {
710 Some(original_indent_width) => {
711 let new_indent_width = indent.width()
712 + original_indent_width
713 .checked_sub(min_prefix_space_width)
715 let new_indent = Indent::from_width(context.config, new_indent_width);
716 format!("{}{}", new_indent.to_string(context.config), line.trim())
718 None => String::new(),
725 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
730 '\t' => width += context.config.tab_spaces(),
737 fn is_empty_line(s: &str) -> bool {
738 s.is_empty() || s.chars().all(char::is_whitespace)
741 // A very simple parser that just parses a macros 2.0 definition into its branches.
742 // Currently we do not attempt to parse any further than that.
749 // (`(` ... `)` `=>` `{` ... `}`)*
750 fn parse(&mut self) -> Option<Macro> {
751 let mut branches = vec![];
752 while self.toks.look_ahead(1).is_some() {
753 branches.push(self.parse_branch()?);
756 Some(Macro { branches })
759 // `(` ... `)` `=>` `{` ... `}`
760 fn parse_branch(&mut self) -> Option<MacroBranch> {
761 let (args_paren_kind, args) = match self.toks.next()? {
762 TokenTree::Token(..) => return None,
763 TokenTree::Delimited(_, ref d) => (d.delim, d.tts.clone()),
765 match self.toks.next()? {
766 TokenTree::Token(_, Token::FatArrow) => {}
769 let body = match self.toks.next()? {
770 TokenTree::Token(..) => return None,
771 TokenTree::Delimited(sp, _) => {
772 let data = sp.data();
773 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt)
776 if let Some(TokenTree::Token(_, Token::Semi)) = self.toks.look_ahead(0) {
787 // A parsed macros 2.0 macro definition.
789 branches: Vec<MacroBranch>,
792 // FIXME: it would be more efficient to use references to the token streams
793 // rather than clone them, if we can make the borrowing work out.
795 args: ThinTokenStream,
796 args_paren_kind: DelimToken,
803 use syntax::parse::{parse_stream_from_source_str, ParseSess};
804 use syntax::codemap::{FileName, FilePathMapping};
806 fn format_macro_args_str(s: &str) -> String {
807 let input = parse_stream_from_source_str(
808 FileName::Custom("stdin".to_owned()),
810 &ParseSess::new(FilePathMapping::empty()),
813 format_macro_args(input.into()).unwrap()
817 fn test_format_macro_args() {
818 assert_eq!(format_macro_args_str(""), "".to_owned());
819 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
821 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
822 "$m1: ident, $m2: ident, $x: ident".to_owned()
825 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
826 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
829 format_macro_args_str(
830 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
832 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()