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.
23 use syntax::codemap::BytePos;
24 use syntax::parse::new_parser_from_tts;
25 use syntax::parse::token::Token;
27 use syntax::tokenstream::TokenStream;
28 use syntax::util::ThinVec;
31 use codemap::SpanUtils;
32 use comment::{contains_comment, FindUncommented};
33 use expr::{rewrite_array, rewrite_call_inner};
34 use rewrite::{Rewrite, RewriteContext};
37 const FORCED_BRACKET_MACROS: &'static [&'static str] = &["vec!"];
39 // FIXME: use the enum from libsyntax?
40 #[derive(Clone, Copy, PartialEq, Eq)]
47 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
48 pub enum MacroPosition {
55 fn opener(&self) -> &'static str {
57 MacroStyle::Parens => "(",
58 MacroStyle::Brackets => "[",
59 MacroStyle::Braces => "{",
66 extra_ident: Option<ast::Ident>,
67 context: &RewriteContext,
69 position: MacroPosition,
71 let mut context = &mut context.clone();
72 context.inside_macro = true;
73 if context.config.use_try_shorthand() {
74 if let Some(expr) = convert_try_mac(mac, context) {
75 return expr.rewrite(context, shape);
79 let original_style = macro_style(mac, context);
81 let macro_name = match extra_ident {
82 None => format!("{}!", mac.node.path),
83 Some(ident) => if ident == symbol::keywords::Invalid.ident() {
84 format!("{}!", mac.node.path)
86 format!("{}! {}", mac.node.path, ident)
90 let style = if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
96 let ts: TokenStream = mac.node.tts.clone().into();
97 if ts.is_empty() && !contains_comment(&context.snippet(mac.span)) {
99 MacroStyle::Parens if position == MacroPosition::Item => {
100 Some(format!("{}();", macro_name))
102 MacroStyle::Parens => Some(format!("{}()", macro_name)),
103 MacroStyle::Brackets => Some(format!("{}[]", macro_name)),
104 MacroStyle::Braces => Some(format!("{}{{}}", macro_name)),
108 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
109 let mut expr_vec = Vec::new();
110 let mut vec_with_semi = false;
111 let mut trailing_comma = false;
113 if MacroStyle::Braces != style {
115 let expr = match parser.parse_expr() {
118 if context.parse_session.span_diagnostic.has_errors() {
119 return Some(context.snippet(mac.span));
126 return Some(context.snippet(mac.span));
136 // Try to parse `vec![expr; expr]`
137 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
139 if parser.token != Token::Eof {
140 match parser.parse_expr() {
142 if context.parse_session.span_diagnostic.has_errors() {
147 if parser.token == Token::Eof && expr_vec.len() == 2 {
148 vec_with_semi = true;
152 Err(mut e) => e.cancel(),
163 if parser.token == Token::Eof {
164 trailing_comma = true;
171 MacroStyle::Parens => {
172 // Format macro invocation as function call, forcing no trailing
173 // comma because not all macros support them.
174 let rw = rewrite_call_inner(
177 &expr_vec.iter().map(|e| &**e).collect::<Vec<_>>()[..],
180 context.config.fn_call_width(),
183 rw.ok().map(|rw| match position {
184 MacroPosition::Item => format!("{};", rw),
188 MacroStyle::Brackets => {
189 let mac_shape = try_opt!(shape.offset_left(macro_name.len()));
190 // Handle special case: `vec![expr; expr]`
192 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
198 let total_overhead = lbr.len() + rbr.len() + 6;
199 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
200 let lhs = try_opt!(expr_vec[0].rewrite(context, nested_shape));
201 let rhs = try_opt!(expr_vec[1].rewrite(context, nested_shape));
202 if !lhs.contains('\n') && !rhs.contains('\n') &&
203 lhs.len() + rhs.len() + total_overhead <= shape.width
205 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
208 "{}{}\n{}{};\n{}{}\n{}{}",
211 nested_shape.indent.to_string(context.config),
213 nested_shape.indent.to_string(context.config),
215 shape.indent.to_string(context.config),
220 // If we are rewriting `vec!` macro or other special macros,
221 // then we can rewrite this as an usual array literal.
222 // Otherwise, we must preserve the original existence of trailing comma.
223 if FORCED_BRACKET_MACROS.contains(&¯o_name.as_str()) {
224 context.inside_macro = false;
225 trailing_comma = false;
227 let rewrite = try_opt!(rewrite_array(
228 expr_vec.iter().map(|x| &**x),
232 .span_after(mac.span, original_style.opener()),
233 mac.span.hi - BytePos(1),
240 Some(format!("{}{}", macro_name, rewrite))
243 MacroStyle::Braces => {
244 // Skip macro invocations with braces, for now.
250 /// Tries to convert a macro use into a short hand try expression. Returns None
251 /// when the macro is not an instance of try! (or parsing the inner expression
253 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
254 if &format!("{}", mac.node.path)[..] == "try" {
255 let ts: TokenStream = mac.node.tts.clone().into();
256 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
259 id: ast::NodeId::new(0), // dummy value
260 node: ast::ExprKind::Try(try_opt!(parser.parse_expr().ok())),
261 span: mac.span, // incorrect span, but shouldn't matter too much
262 attrs: ThinVec::new(),
269 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
270 let snippet = context.snippet(mac.span);
271 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
272 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
273 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
275 if paren_pos < bracket_pos && paren_pos < brace_pos {
277 } else if bracket_pos < brace_pos {