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};
29 use rewrite::RewriteContext;
30 use expr::{rewrite_call, rewrite_array};
31 use comment::FindUncommented;
34 // We need to pass `TokenTree`s to our expression parsing thread, but they are
35 // not `Send`. We wrap them in a `Send` container to force our will.
36 // FIXME: this is a pretty terrible hack. Any other solution would be preferred.
37 struct ForceSend<T>(pub T);
38 unsafe impl<T> Send for ForceSend<T> {}
40 // FIXME: use the enum from libsyntax?
47 pub fn rewrite_macro(mac: &ast::Mac,
48 context: &RewriteContext,
52 let ast::Mac_::MacInvocTT(ref path, ref tt_vec, _) = mac.node;
53 let style = macro_style(mac, context);
54 let macro_name = format!("{}!", path);
56 if let MacroStyle::Braces = style {
58 } else if tt_vec.is_empty() {
59 return if let MacroStyle::Parens = style {
60 Some(format!("{}()", macro_name))
62 Some(format!("{}[]", macro_name))
66 let wrapped_tt_vec = ForceSend((*tt_vec).clone());
67 // Wrap expression parsing logic in a thread since the libsyntax parser
68 // panicks on failure, which we do not want to propagate.
69 let expr_vec_result = thread::catch_panic(move || {
70 let parse_session = ParseSess::new();
71 let mut parser = tts_to_parser(&parse_session, wrapped_tt_vec.0, vec![]);
72 let mut expr_vec = vec![];
75 expr_vec.push(parser.parse_expr());
80 _ => panic!("Macro not list-like, skiping..."),
83 let _ = parser.bump();
88 let expr_vec = try_opt!(expr_vec_result.ok());
91 MacroStyle::Parens => {
92 // Format macro invocation as function call.
93 rewrite_call(context, ¯o_name, &expr_vec, mac.span, width, offset)
95 MacroStyle::Brackets => {
96 // Format macro invocation as array literal.
97 let extra_offset = macro_name.len();
98 let rewrite = try_opt!(rewrite_array(expr_vec.iter().map(|x| &**x),
101 try_opt!(width.checked_sub(extra_offset)),
102 offset + extra_offset));
103 Some(format!("{}{}", macro_name, rewrite))
105 MacroStyle::Braces => {
106 // Skip macro invocations with braces, for now.
107 wrap_str(context.snippet(mac.span), context.config.max_width, width, offset)
112 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
113 let snippet = context.snippet(mac.span);
114 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
115 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
116 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
118 if paren_pos < bracket_pos && paren_pos < brace_pos {
120 } else if bracket_pos < brace_pos {