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};
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 if ts.is_empty() && !contains_comment(context.snippet(mac.span)) {
160 MacroStyle::Parens if position == MacroPosition::Item => {
161 Some(format!("{}();", macro_name))
163 MacroStyle::Parens => Some(format!("{}()", macro_name)),
164 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
165 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
169 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
170 let mut arg_vec = Vec::new();
171 let mut vec_with_semi = false;
172 let mut trailing_comma = false;
174 if MacroStyle::Braces != style {
176 match parse_macro_arg(&mut parser) {
177 Some(arg) => arg_vec.push(arg),
178 None => return Some(context.snippet(mac.span).to_owned()),
185 // Try to parse `vec![expr; expr]`
186 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
188 if parser.token != Token::Eof {
189 match parse_macro_arg(&mut parser) {
193 if parser.token == Token::Eof && arg_vec.len() == 2 {
194 vec_with_semi = true;
198 None => return Some(context.snippet(mac.span).to_owned()),
202 return Some(context.snippet(mac.span).to_owned());
204 _ => return Some(context.snippet(mac.span).to_owned()),
209 if parser.token == Token::Eof {
210 trailing_comma = true;
217 MacroStyle::Parens => {
218 // Format macro invocation as function call, forcing no trailing
219 // comma because not all macros support them.
223 &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..],
226 context.config.width_heuristics().fn_call_width,
228 ).map(|rw| match position {
229 MacroPosition::Item => format!("{};", rw),
233 MacroStyle::Brackets => {
234 let mac_shape = shape.offset_left(macro_name.len())?;
235 // Handle special case: `vec![expr; expr]`
237 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
243 let total_overhead = lbr.len() + rbr.len() + 6;
244 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
245 let lhs = arg_vec[0].rewrite(context, nested_shape)?;
246 let rhs = arg_vec[1].rewrite(context, nested_shape)?;
247 if !lhs.contains('\n') && !rhs.contains('\n')
248 && lhs.len() + rhs.len() + total_overhead <= shape.width
250 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
256 nested_shape.indent.to_string_with_newline(context.config),
258 nested_shape.indent.to_string_with_newline(context.config),
260 shape.indent.to_string_with_newline(context.config),
265 // If we are rewriting `vec!` macro or other special macros,
266 // then we can rewrite this as an usual array literal.
267 // Otherwise, we must preserve the original existence of trailing comma.
268 if FORCED_BRACKET_MACROS.contains(¯o_name.as_str()) {
269 context.inside_macro = false;
270 trailing_comma = false;
272 // Convert `MacroArg` into `ast::Expr`, as `rewrite_array` only accepts the latter.
276 .span_after(mac.span, original_style.opener()),
277 mac.span.hi() - BytePos(1),
279 let arg_vec = &arg_vec.iter().map(|e| &*e).collect::<Vec<_>>()[..];
280 let rewrite = rewrite_array(arg_vec, sp, context, mac_shape, trailing_comma)?;
282 Some(format!("{}{}", macro_name, rewrite))
285 MacroStyle::Braces => {
286 // Skip macro invocations with braces, for now.
287 indent_macro_snippet(context, context.snippet(mac.span), shape.indent)
292 pub fn rewrite_macro_def(
293 context: &RewriteContext,
298 vis: &ast::Visibility,
300 ) -> Option<String> {
301 let snippet = Some(remove_trailing_white_spaces(context.snippet(span)));
302 if snippet.as_ref().map_or(true, |s| s.ends_with(';')) {
306 let mut parser = MacroParser::new(def.stream().into_trees());
307 let parsed_def = match parser.parse() {
309 None => return snippet,
312 let mut result = if def.legacy {
313 String::from("macro_rules!")
315 format!("{}macro", format_visibility(vis))
319 result += &ident.name.as_str();
321 let multi_branch_style = def.legacy || parsed_def.branches.len() != 1;
323 let arm_shape = if multi_branch_style {
325 .block_indent(context.config.tab_spaces())
326 .with_max_width(context.config)
331 let branch_items = itemize_list(
332 context.snippet_provider,
333 parsed_def.branches.iter(),
336 |branch| branch.span.lo(),
337 |branch| branch.span.hi(),
338 |branch| branch.rewrite(context, arm_shape, multi_branch_style),
339 context.snippet_provider.span_after(span, "{"),
342 ).collect::<Vec<_>>();
344 let fmt = ListFormatting {
345 tactic: DefinitiveListTactic::Vertical,
346 separator: if def.legacy { ";" } else { "" },
347 trailing_separator: SeparatorTactic::Always,
348 separator_place: SeparatorPlace::Back,
350 ends_with_newline: true,
351 preserve_newline: true,
352 config: context.config,
355 if multi_branch_style {
357 result += &arm_shape.indent.to_string_with_newline(context.config);
360 result += write_list(&branch_items, &fmt)?.as_str();
362 if multi_branch_style {
363 result += &indent.to_string_with_newline(context.config);
370 // Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
371 // aren't causing problems.
372 // This should also work for escaped `$` variables, where we leave earlier `$`s.
373 fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
374 // Each substitution will require five or six extra bytes.
375 let mut result = String::with_capacity(input.len() + 64);
376 let mut substs = HashMap::new();
377 let mut dollar_count = 0;
378 let mut cur_name = String::new();
380 for c in input.chars() {
383 } else if dollar_count == 0 {
385 } else if !c.is_alphanumeric() && !cur_name.is_empty() {
386 // Terminates a name following one or more dollars.
387 let mut new_name = String::new();
388 let mut old_name = String::new();
390 for _ in 0..(dollar_count - 1) {
395 new_name.push_str(&cur_name);
396 old_name.push_str(&cur_name);
398 result.push_str(&new_name);
399 substs.insert(old_name, new_name);
404 cur_name = String::new();
405 } else if c == '(' && cur_name.is_empty() {
406 // FIXME: Support macro def with repeat.
408 } else if c.is_alphanumeric() {
413 // FIXME: duplicate code
414 if !cur_name.is_empty() {
415 let mut new_name = String::new();
416 let mut old_name = String::new();
418 for _ in 0..(dollar_count - 1) {
423 new_name.push_str(&cur_name);
424 old_name.push_str(&cur_name);
426 result.push_str(&new_name);
427 substs.insert(old_name, new_name);
430 debug!("replace_names `{}` {:?}", result, substs);
432 Some((result, substs))
435 // This is a bit sketchy. The token rules probably need tweaking, but it works
436 // for some common cases. I hope the basic logic is sufficient. Note that the
437 // meaning of some tokens is a bit different here from usual Rust, e.g., `*`
438 // and `(`/`)` have special meaning.
440 // We always try and format on one line.
441 // FIXME: Use multi-line when every thing does not fit on one line.
442 fn format_macro_args(toks: ThinTokenStream, shape: Shape) -> Option<String> {
443 let mut result = String::with_capacity(128);
444 let mut insert_space = SpaceState::Never;
446 for tok in (toks.into(): TokenStream).trees() {
448 TokenTree::Token(_, t) => {
449 if !result.is_empty() && force_space_before(&t) {
450 insert_space = SpaceState::Always;
452 if force_no_space_before(&t) {
453 insert_space = SpaceState::Never;
455 match (insert_space, ident_like(&t)) {
456 (SpaceState::Always, _)
457 | (SpaceState::Punctuation, false)
458 | (SpaceState::Ident, true) => {
463 result.push_str(&pprust::token_to_string(&t));
464 insert_space = next_space(&t);
466 TokenTree::Delimited(_, d) => {
467 if let SpaceState::Always = insert_space {
470 let formatted = format_macro_args(d.tts, shape)?;
472 DelimToken::Paren => {
473 result.push_str(&format!("({})", formatted));
474 insert_space = SpaceState::Always;
476 DelimToken::Bracket => {
477 result.push_str(&format!("[{}]", formatted));
478 insert_space = SpaceState::Always;
480 DelimToken::Brace => {
481 result.push_str(&format!(" {{ {} }}", formatted));
482 insert_space = SpaceState::Always;
484 DelimToken::NoDelim => {
485 result.push_str(&format!("{}", formatted));
486 insert_space = SpaceState::Always;
493 if result.len() <= shape.width {
500 // We should insert a space if the next token is a:
501 #[derive(Copy, Clone)]
505 Ident, // Or ident/literal-like thing.
509 fn force_space_before(tok: &Token) -> bool {
528 | Token::Dollar => true,
529 Token::BinOp(bot) => bot != BinOpToken::Star,
534 fn force_no_space_before(tok: &Token) -> bool {
536 Token::Semi | Token::Comma | Token::Dot => true,
537 Token::BinOp(bot) => bot == BinOpToken::Star,
541 fn ident_like(tok: &Token) -> bool {
543 Token::Ident(_) | Token::Literal(..) | Token::Lifetime(_) => true,
548 fn next_space(tok: &Token) -> SpaceState {
561 | Token::BinOp(_) => SpaceState::Punctuation,
566 | Token::OpenDelim(_)
567 | Token::CloseDelim(_)
568 | Token::Whitespace => SpaceState::Never,
570 Token::Literal(..) | Token::Ident(_) | Token::Lifetime(_) => SpaceState::Ident,
572 _ => SpaceState::Always,
576 /// Tries to convert a macro use into a short hand try expression. Returns None
577 /// when the macro is not an instance of try! (or parsing the inner expression
579 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
580 if &format!("{}", mac.node.path)[..] == "try" {
581 let ts: TokenStream = mac.node.tts.clone().into();
582 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
585 id: ast::NodeId::new(0), // dummy value
586 node: ast::ExprKind::Try(parser.parse_expr().ok()?),
587 span: mac.span, // incorrect span, but shouldn't matter too much
588 attrs: ThinVec::new(),
595 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
596 let snippet = context.snippet(mac.span);
597 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
598 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
599 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
601 if paren_pos < bracket_pos && paren_pos < brace_pos {
603 } else if bracket_pos < brace_pos {
610 /// Indent each line according to the specified `indent`.
635 fn indent_macro_snippet(
636 context: &RewriteContext,
639 ) -> Option<String> {
640 let mut lines = macro_str.lines();
641 let first_line = lines.next().map(|s| s.trim_right())?;
642 let mut trimmed_lines = Vec::with_capacity(16);
644 let min_prefix_space_width = lines
646 let prefix_space_width = if is_empty_line(line) {
649 Some(get_prefix_space_width(context, line))
651 trimmed_lines.push((line.trim(), prefix_space_width));
657 String::from(first_line) + "\n"
660 .map(|&(line, prefix_space_width)| match prefix_space_width {
661 Some(original_indent_width) => {
662 let new_indent_width = indent.width()
663 + original_indent_width
664 .checked_sub(min_prefix_space_width)
666 let new_indent = Indent::from_width(context.config, new_indent_width);
667 format!("{}{}", new_indent.to_string(context.config), line.trim())
669 None => String::new(),
676 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
681 '\t' => width += context.config.tab_spaces(),
688 fn is_empty_line(s: &str) -> bool {
689 s.is_empty() || s.chars().all(char::is_whitespace)
692 // A very simple parser that just parses a macros 2.0 definition into its branches.
693 // Currently we do not attempt to parse any further than that.
700 // (`(` ... `)` `=>` `{` ... `}`)*
701 fn parse(&mut self) -> Option<Macro> {
702 let mut branches = vec![];
703 while self.toks.look_ahead(1).is_some() {
704 branches.push(self.parse_branch()?);
707 Some(Macro { branches })
710 // `(` ... `)` `=>` `{` ... `}`
711 fn parse_branch(&mut self) -> Option<MacroBranch> {
712 let tok = self.toks.next()?;
713 let (lo, args_paren_kind) = match tok {
714 TokenTree::Token(..) => return None,
715 TokenTree::Delimited(sp, ref d) => (sp.lo(), d.delim),
717 let args = tok.joint().into();
718 match self.toks.next()? {
719 TokenTree::Token(_, Token::FatArrow) => {}
722 let (mut hi, body) = match self.toks.next()? {
723 TokenTree::Token(..) => return None,
724 TokenTree::Delimited(sp, _) => {
725 let data = sp.data();
728 Span::new(data.lo + BytePos(1), data.hi - BytePos(1), data.ctxt),
732 if let Some(TokenTree::Token(sp, Token::Semi)) = self.toks.look_ahead(0) {
745 // A parsed macros 2.0 macro definition.
747 branches: Vec<MacroBranch>,
750 // FIXME: it would be more efficient to use references to the token streams
751 // rather than clone them, if we can make the borrowing work out.
754 args_paren_kind: DelimToken,
755 args: ThinTokenStream,
762 context: &RewriteContext,
764 multi_branch_style: bool,
765 ) -> Option<String> {
766 // Only attempt to format function-like macros.
767 if self.args_paren_kind != DelimToken::Paren {
768 // FIXME(#1539): implement for non-sugared macros.
773 let mut result = format_macro_args(self.args.clone(), shape.sub_width(5)?)?;
775 if multi_branch_style {
779 // The macro body is the most interesting part. It might end up as various
780 // AST nodes, but also has special variables (e.g, `$foo`) which can't be
781 // parsed as regular Rust code (and note that these can be escaped using
782 // `$$`). We'll try and format like an AST node, but we'll substitute
783 // variables for new names with the same length first.
785 let old_body = context.snippet(self.body).trim();
786 let (body_str, substs) = replace_names(old_body)?;
788 let mut config = context.config.clone();
789 config.set().hide_parse_errors(true);
793 let has_block_body = old_body.starts_with('{');
795 let body_indent = if has_block_body {
798 // We'll hack the indent below, take this into account when formatting,
799 let body_indent = shape.indent.block_indent(&config);
800 let new_width = config.max_width() - body_indent.width();
801 config.set().max_width(new_width);
805 // First try to format as items, then as statements.
806 let new_body = match ::format_snippet(&body_str, &config) {
807 Some(new_body) => new_body,
808 None => match ::format_code_block(&body_str, &config) {
809 Some(new_body) => new_body,
814 // Indent the body since it is in a block.
815 let indent_str = body_indent.to_string(&config);
816 let mut new_body = new_body
819 .fold(String::new(), |mut s, l| {
826 // Undo our replacement of macro variables.
827 // FIXME: this could be *much* more efficient.
828 for (old, new) in &substs {
829 if old_body.find(new).is_some() {
830 debug!("rewrite_macro_def: bailing matching variable: `{}`", new);
833 new_body = new_body.replace(new, old);
837 result += new_body.trim();
838 } else if !new_body.is_empty() {
841 result += &shape.indent.to_string(&config);
853 use syntax::parse::{parse_stream_from_source_str, ParseSess};
854 use syntax::codemap::{FileName, FilePathMapping};
856 fn format_macro_args_str(s: &str) -> String {
857 let input = parse_stream_from_source_str(
858 FileName::Custom("stdin".to_owned()),
860 &ParseSess::new(FilePathMapping::empty()),
865 indent: Indent::empty(),
868 format_macro_args(input.into(), shape).unwrap()
872 fn test_format_macro_args() {
873 assert_eq!(format_macro_args_str(""), "".to_owned());
874 assert_eq!(format_macro_args_str("$ x : ident"), "$x: ident".to_owned());
876 format_macro_args_str("$ m1 : ident , $ m2 : ident , $ x : ident"),
877 "$m1: ident, $m2: ident, $x: ident".to_owned()
880 format_macro_args_str("$($beginning:ident),*;$middle:ident;$($end:ident),*"),
881 "$($beginning: ident),*; $middle: ident; $($end: ident),*".to_owned()
884 format_macro_args_str(
885 "$ name : ident ( $ ( $ dol : tt $ var : ident ) * ) $ ( $ body : tt ) *"
887 "$name: ident($($dol: tt $var: ident)*) $($body: tt)*".to_owned()