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 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 indent_macro_snippet(
121 &context.snippet(mac.span),
130 return indent_macro_snippet(context, &context.snippet(mac.span), shape.indent);
140 // Try to parse `vec![expr; expr]`
141 if FORCED_BRACKET_MACROS.contains(&¯o_name[..]) {
143 if parser.token != Token::Eof {
144 match parser.parse_expr() {
146 if context.parse_session.span_diagnostic.has_errors() {
151 if parser.token == Token::Eof && expr_vec.len() == 2 {
152 vec_with_semi = true;
156 Err(mut e) => e.cancel(),
167 if parser.token == Token::Eof {
168 trailing_comma = true;
175 MacroStyle::Parens => {
176 // Format macro invocation as function call, forcing no trailing
177 // comma because not all macros support them.
178 let rw = rewrite_call_inner(
181 &expr_vec.iter().map(|e| &**e).collect::<Vec<_>>()[..],
184 context.config.fn_call_width(),
187 rw.ok().map(|rw| match position {
188 MacroPosition::Item => format!("{};", rw),
192 MacroStyle::Brackets => {
193 let mac_shape = try_opt!(shape.offset_left(macro_name.len()));
194 // Handle special case: `vec![expr; expr]`
196 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
202 let total_overhead = lbr.len() + rbr.len() + 6;
203 let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
204 let lhs = try_opt!(expr_vec[0].rewrite(context, nested_shape));
205 let rhs = try_opt!(expr_vec[1].rewrite(context, nested_shape));
206 if !lhs.contains('\n') && !rhs.contains('\n') &&
207 lhs.len() + rhs.len() + total_overhead <= shape.width
209 Some(format!("{}{}{}; {}{}", macro_name, lbr, lhs, rhs, rbr))
212 "{}{}\n{}{};\n{}{}\n{}{}",
215 nested_shape.indent.to_string(context.config),
217 nested_shape.indent.to_string(context.config),
219 shape.indent.to_string(context.config),
224 // If we are rewriting `vec!` macro or other special macros,
225 // then we can rewrite this as an usual array literal.
226 // Otherwise, we must preserve the original existence of trailing comma.
227 if FORCED_BRACKET_MACROS.contains(&¯o_name.as_str()) {
228 context.inside_macro = false;
229 trailing_comma = false;
231 let rewrite = try_opt!(rewrite_array(
232 expr_vec.iter().map(|x| &**x),
236 .span_after(mac.span, original_style.opener()),
237 mac.span.hi - BytePos(1),
244 Some(format!("{}{}", macro_name, rewrite))
247 MacroStyle::Braces => {
248 // Skip macro invocations with braces, for now.
249 indent_macro_snippet(context, &context.snippet(mac.span), shape.indent)
254 /// Tries to convert a macro use into a short hand try expression. Returns None
255 /// when the macro is not an instance of try! (or parsing the inner expression
257 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
258 if &format!("{}", mac.node.path)[..] == "try" {
259 let ts: TokenStream = mac.node.tts.clone().into();
260 let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
263 id: ast::NodeId::new(0), // dummy value
264 node: ast::ExprKind::Try(try_opt!(parser.parse_expr().ok())),
265 span: mac.span, // incorrect span, but shouldn't matter too much
266 attrs: ThinVec::new(),
273 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
274 let snippet = context.snippet(mac.span);
275 let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());
276 let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::max_value());
277 let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::max_value());
279 if paren_pos < bracket_pos && paren_pos < brace_pos {
281 } else if bracket_pos < brace_pos {
288 /// Indent each line according to the specified `indent`.
313 fn indent_macro_snippet(
314 context: &RewriteContext,
317 ) -> Option<String> {
318 let mut lines = macro_str.lines();
319 let first_line = try_opt!(lines.next().map(|s| s.trim_right()));
320 let mut trimmed_lines = Vec::with_capacity(16);
322 let min_prefix_space_width = try_opt!(
325 let prefix_space_width = if is_empty_line(line) {
328 Some(get_prefix_space_width(context, line))
330 trimmed_lines.push((line.trim(), prefix_space_width));
337 String::from(first_line) + "\n" +
340 .map(|&(line, prefix_space_width)| match prefix_space_width {
341 Some(original_indent_width) => {
342 let new_indent_width = indent.width() +
343 original_indent_width
344 .checked_sub(min_prefix_space_width)
346 let new_indent = Indent::from_width(context.config, new_indent_width);
347 new_indent.to_string(context.config) + line.trim()
349 None => String::new(),
356 fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
358 let mut iter = s.chars();
359 while let Some(c) = iter.next() {
362 '\t' => width += context.config.tab_spaces(),
369 fn is_empty_line(s: &str) -> bool {
370 s.is_empty() || s.chars().all(char::is_whitespace)