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.
25 use syntax::parse::token::{Eof, Comma, Token};
26 use syntax::parse::{ParseSess, tts_to_parser};
27 use syntax::codemap::{mk_sp, BytePos};
30 use rewrite::RewriteContext;
31 use expr::{rewrite_call, rewrite_array};
32 use comment::FindUncommented;
33 use utils::{wrap_str, span_after};
35 static FORCED_BRACKET_MACROS: &'static [&'static str] = &["vec!"];
37 // We need to pass `TokenTree`s to our expression parsing thread, but they are
38 // not `Send`. We wrap them in a `Send` container to force our will.
39 // FIXME: this is a pretty terrible hack. Any other solution would be preferred.
40 struct ForceSend<T>(pub T);
41 unsafe impl<T> Send for ForceSend<T> {}
43 // FIXME: use the enum from libsyntax?
44 #[derive(Clone, Copy)]
52 fn opener(&self) -> &'static str {
54 MacroStyle::Parens => "(",
55 MacroStyle::Brackets => "[",
56 MacroStyle::Braces => "{",
61 pub fn rewrite_macro(mac: &ast::Mac,
62 context: &RewriteContext,
66 let original_style = macro_style(mac, context);
67 let macro_name = format!("{}!", mac.node.path);
68 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
74 if let MacroStyle::Braces = style {
76 } else if mac.node.tts.is_empty() {
77 return if let MacroStyle::Parens = style {
78 Some(format!("{}()", macro_name))
80 Some(format!("{}[]", macro_name))
84 let wrapped_tt_vec = ForceSend(mac.node.tts.clone());
85 // Wrap expression parsing logic in a thread since the libsyntax parser
86 // panics on failure, which we do not want to propagate.
87 // The expression vector is wrapped in an Option inside a Result.
88 let expr_vec_result = thread::catch_panic(move || {
89 let parse_session = ParseSess::new();
90 let mut parser = tts_to_parser(&parse_session, wrapped_tt_vec.0, vec![]);
91 let mut expr_vec = vec![];
94 expr_vec.push(parser.parse_expr());
99 _ => panic!("Macro not list-like, skiping..."),
102 let _ = parser.bump();
104 if parser.token == Token::Eof {
111 let expr_vec = try_opt!(try_opt!(expr_vec_result.ok()));
114 MacroStyle::Parens => {
115 // Format macro invocation as function call.
116 rewrite_call(context, ¯o_name, &expr_vec, mac.span, width, offset)
118 MacroStyle::Brackets => {
119 // Format macro invocation as array literal.
120 let extra_offset = macro_name.len();
121 let rewrite = try_opt!(rewrite_array(expr_vec.iter().map(|x| &**x),
122 mk_sp(span_after(mac.span,
123 original_style.opener(),
125 mac.span.hi - BytePos(1)),
127 try_opt!(width.checked_sub(extra_offset)),
128 offset + extra_offset));
130 Some(format!("{}{}", macro_name, rewrite))
132 MacroStyle::Braces => {
133 // Skip macro invocations with braces, for now.
134 wrap_str(context.snippet(mac.span),
135 context.config.max_width,
142 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
143 let snippet = context.snippet(mac.span);
144 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
145 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
146 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
148 if paren_pos < bracket_pos && paren_pos < brace_pos {
150 } else if bracket_pos < brace_pos {