src/visitor.rs

   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.
   4 //
   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.
  10
  11 use syntax::ast;
  12 use syntax::codemap::{self, CodeMap, Span, BytePos};
  13 use syntax::visit;
  14 use syntax::parse::token;
  15 use syntax::attr;
  16 use std::path::PathBuf;
  17
  18 use utils;
  19 use config::Config;
  20 use comment::FindUncommented;
  21
  22 use changes::ChangeSet;
  23 use rewrite::{Rewrite, RewriteContext};
  24
  25 pub struct FmtVisitor<'a> {
  26     pub codemap: &'a CodeMap,
  27     pub changes: ChangeSet<'a>,
  28     pub last_pos: BytePos,
  29     // TODO RAII util for indenting
  30     pub block_indent: usize,
  31     pub config: &'a Config,
  32 }
  33
  34 impl<'a, 'v> visit::Visitor<'v> for FmtVisitor<'a> {
  35     fn visit_expr(&mut self, ex: &'v ast::Expr) {
  36         debug!("visit_expr: {:?} {:?}",
  37                self.codemap.lookup_char_pos(ex.span.lo),
  38                self.codemap.lookup_char_pos(ex.span.hi));
  39         self.format_missing(ex.span.lo);
  40         let offset = self.changes.cur_offset_span(ex.span);
  41         let context = RewriteContext { codemap: self.codemap,
  42                                        config: self.config,
  43                                        block_indent: self.block_indent, };
  44         let rewrite = ex.rewrite(&context, self.config.max_width - offset, offset);
  45
  46         if let Some(new_str) = rewrite {
  47             self.changes.push_str_span(ex.span, &new_str);
  48             self.last_pos = ex.span.hi;
  49         }
  50     }
  51
  52     fn visit_stmt(&mut self, stmt: &'v ast::Stmt) {
  53         // If the stmt is actually an item, then we'll handle any missing spans
  54         // there. This is important because of annotations.
  55         // Although it might make more sense for the statement span to include
  56         // any annotations on the item.
  57         let skip_missing = match stmt.node {
  58             ast::Stmt_::StmtDecl(ref decl, _) => {
  59                 match decl.node {
  60                     ast::Decl_::DeclItem(_) => true,
  61                     _ => false,
  62                 }
  63             }
  64             _ => false,
  65         };
  66         if !skip_missing {
  67             self.format_missing_with_indent(stmt.span.lo);
  68         }
  69         visit::walk_stmt(self, stmt);
  70     }
  71
  72     fn visit_block(&mut self, b: &'v ast::Block) {
  73         debug!("visit_block: {:?} {:?}",
  74                self.codemap.lookup_char_pos(b.span.lo),
  75                self.codemap.lookup_char_pos(b.span.hi));
  76         self.format_missing(b.span.lo);
  77
  78         self.changes.push_str_span(b.span, "{");
  79         self.last_pos = self.last_pos + BytePos(1);
  80         self.block_indent += self.config.tab_spaces;
  81
  82         for stmt in &b.stmts {
  83             self.visit_stmt(&stmt)
  84         }
  85         match b.expr {
  86             Some(ref e) => {
  87                 self.format_missing_with_indent(e.span.lo);
  88                 self.visit_expr(e);
  89             }
  90             None => {}
  91         }
  92
  93         self.block_indent -= self.config.tab_spaces;
  94         // TODO we should compress any newlines here to just one
  95         self.format_missing_with_indent(b.span.hi - BytePos(1));
  96         self.changes.push_str_span(b.span, "}");
  97         self.last_pos = b.span.hi;
  98     }
  99
 100     // Note that this only gets called for function definitions. Required methods
 101     // on traits do not get handled here.
 102     fn visit_fn(&mut self,
 103                 fk: visit::FnKind<'v>,
 104                 fd: &'v ast::FnDecl,
 105                 b: &'v ast::Block,
 106                 s: Span,
 107                 _: ast::NodeId) {
 108         self.format_missing_with_indent(s.lo);
 109         self.last_pos = s.lo;
 110
 111         let indent = self.block_indent;
 112         match fk {
 113             visit::FkItemFn(ident,
 114                             ref generics,
 115                             ref unsafety,
 116                             ref constness,
 117                             ref abi,
 118                             vis) => {
 119                 let new_fn = self.rewrite_fn(indent,
 120                                              ident,
 121                                              fd,
 122                                              None,
 123                                              generics,
 124                                              unsafety,
 125                                              constness,
 126                                              abi,
 127                                              vis,
 128                                              codemap::mk_sp(s.lo, b.span.lo));
 129                 self.changes.push_str_span(s, &new_fn);
 130             }
 131             visit::FkMethod(ident, ref sig, vis) => {
 132                 let new_fn = self.rewrite_fn(indent,
 133                                              ident,
 134                                              fd,
 135                                              Some(&sig.explicit_self),
 136                                              &sig.generics,
 137                                              &sig.unsafety,
 138                                              &sig.constness,
 139                                              &sig.abi,
 140                                              vis.unwrap_or(ast::Visibility::Inherited),
 141                                              codemap::mk_sp(s.lo, b.span.lo));
 142                 self.changes.push_str_span(s, &new_fn);
 143             }
 144             visit::FkFnBlock(..) => {}
 145         }
 146
 147         self.last_pos = b.span.lo;
 148         self.visit_block(b)
 149     }
 150
 151     fn visit_item(&mut self, item: &'v ast::Item) {
 152         // Don't look at attributes for modules.
 153         // We want to avoid looking at attributes in another file, which the AST
 154         // doesn't distinguish. FIXME This is overly conservative and means we miss
 155         // attributes on inline modules.
 156         match item.node {
 157             ast::Item_::ItemMod(_) => {}
 158             _ => {
 159                 if self.visit_attrs(&item.attrs) {
 160                     return;
 161                 }
 162             }
 163         }
 164
 165         match item.node {
 166             ast::Item_::ItemUse(ref vp) => {
 167                 match vp.node {
 168                     ast::ViewPath_::ViewPathList(ref path, ref path_list) => {
 169                         let block_indent = self.block_indent;
 170                         let one_line_budget = self.config.max_width - block_indent;
 171                         let multi_line_budget = self.config.ideal_width - block_indent;
 172                         let formatted = self.rewrite_use_list(block_indent,
 173                                                               one_line_budget,
 174                                                               multi_line_budget,
 175                                                               path,
 176                                                               path_list,
 177                                                               item.vis,
 178                                                               item.span);
 179
 180                         if let Some(new_str) = formatted {
 181                             self.format_missing_with_indent(item.span.lo);
 182                             self.changes.push_str_span(item.span, &new_str);
 183                         } else {
 184                             // Format up to last newline
 185                             let span = codemap::mk_sp(self.last_pos, item.span.lo);
 186                             let span_end = match self.snippet(span).rfind('\n') {
 187                                 Some(offset) => self.last_pos + BytePos(offset as u32),
 188                                 None => item.span.lo
 189                             };
 190                             self.format_missing(span_end);
 191                         }
 192
 193                         self.last_pos = item.span.hi;
 194                     }
 195                     ast::ViewPath_::ViewPathGlob(_) => {
 196                         self.format_missing_with_indent(item.span.lo);
 197                         // FIXME convert to list?
 198                     }
 199                     ast::ViewPath_::ViewPathSimple(_,_) => {
 200                         self.format_missing_with_indent(item.span.lo);
 201                     }
 202                 }
 203                 visit::walk_item(self, item);
 204             }
 205             ast::Item_::ItemImpl(..) |
 206             ast::Item_::ItemTrait(..) => {
 207                 self.block_indent += self.config.tab_spaces;
 208                 visit::walk_item(self, item);
 209                 self.block_indent -= self.config.tab_spaces;
 210             }
 211             ast::Item_::ItemExternCrate(_) => {
 212                 self.format_missing_with_indent(item.span.lo);
 213                 let new_str = self.snippet(item.span);
 214                 self.changes.push_str_span(item.span, &new_str);
 215                 self.last_pos = item.span.hi;
 216             }
 217             ast::Item_::ItemStruct(ref def, ref generics) => {
 218                 self.format_missing_with_indent(item.span.lo);
 219                 self.visit_struct(item.ident,
 220                                   item.vis,
 221                                   def,
 222                                   generics,
 223                                   item.span);
 224                 self.last_pos = item.span.hi;
 225             }
 226             ast::Item_::ItemEnum(ref def, ref generics) => {
 227                 self.format_missing_with_indent(item.span.lo);
 228                 self.visit_enum(item.ident,
 229                                 item.vis,
 230                                 def,
 231                                 generics,
 232                                 item.span);
 233                 self.last_pos = item.span.hi;
 234             }
 235             ast::Item_::ItemMod(ref module) => {
 236                 self.format_missing_with_indent(item.span.lo);
 237                 self.format_mod(module, item.span, item.ident, &item.attrs);
 238             }
 239             _ => {
 240                 visit::walk_item(self, item);
 241             }
 242         }
 243     }
 244
 245     fn visit_trait_item(&mut self, ti: &'v ast::TraitItem) {
 246         if self.visit_attrs(&ti.attrs) {
 247             return;
 248         }
 249
 250         if let ast::TraitItem_::MethodTraitItem(ref sig, None) = ti.node {
 251             self.format_missing_with_indent(ti.span.lo);
 252
 253             let indent = self.block_indent;
 254             let new_fn = self.rewrite_required_fn(indent,
 255                                                   ti.ident,
 256                                                   sig,
 257                                                   ti.span);
 258
 259             self.changes.push_str_span(ti.span, &new_fn);
 260             self.last_pos = ti.span.hi;
 261         }
 262         // TODO format trait types
 263
 264         visit::walk_trait_item(self, ti)
 265     }
 266
 267     fn visit_impl_item(&mut self, ii: &'v ast::ImplItem) {
 268         if self.visit_attrs(&ii.attrs) {
 269             return;
 270         }
 271         visit::walk_impl_item(self, ii)
 272     }
 273
 274     fn visit_mac(&mut self, mac: &'v ast::Mac) {
 275         visit::walk_mac(self, mac)
 276     }
 277
 278     fn visit_mod(&mut self, m: &'v ast::Mod, s: Span, _: ast::NodeId) {
 279         // This is only called for the root module
 280         let filename = self.codemap.span_to_filename(s);
 281         self.format_separate_mod(m, &filename);
 282     }
 283 }
 284
 285 impl<'a> FmtVisitor<'a> {
 286     pub fn from_codemap<'b>(codemap: &'b CodeMap, config: &'b Config) -> FmtVisitor<'b> {
 287         FmtVisitor { codemap: codemap,
 288                      changes: ChangeSet::from_codemap(codemap),
 289                      last_pos: BytePos(0),
 290                      block_indent: 0,
 291                      config: config, }
 292     }
 293
 294     pub fn snippet(&self, span: Span) -> String {
 295         match self.codemap.span_to_snippet(span) {
 296             Ok(s) => s,
 297             Err(_) => {
 298                 println!("Couldn't make snippet for span {:?}->{:?}",
 299                          self.codemap.lookup_char_pos(span.lo),
 300                          self.codemap.lookup_char_pos(span.hi));
 301                 "".to_owned()
 302             }
 303         }
 304     }
 305
 306     // Returns true if we should skip the following item.
 307     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 308         if attrs.len() == 0 {
 309             return false;
 310         }
 311
 312         let first = &attrs[0];
 313         self.format_missing_with_indent(first.span.lo);
 314
 315         if utils::contains_skip(attrs) {
 316             true
 317         } else {
 318             let rewrite = self.rewrite_attrs(attrs, self.block_indent);
 319             self.changes.push_str_span(first.span, &rewrite);
 320             let last = attrs.last().unwrap();
 321             self.last_pos = last.span.hi;
 322             false
 323         }
 324     }
 325
 326     pub fn rewrite_attrs(&self, attrs: &[ast::Attribute], indent: usize) -> String {
 327         let mut result = String::new();
 328         let indent = utils::make_indent(indent);
 329
 330         for (i, a) in attrs.iter().enumerate() {
 331             let a_str = self.snippet(a.span);
 332
 333             if i > 0 {
 334                 let comment = self.snippet(codemap::mk_sp(attrs[i-1].span.hi, a.span.lo));
 335                 // This particular horror show is to preserve line breaks in between doc
 336                 // comments. An alternative would be to force such line breaks to start
 337                 // with the usual doc comment token.
 338                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 339                 let comment = comment.trim();
 340                 if comment.len() > 0 {
 341                     result.push_str(&indent);
 342                     result.push_str(comment);
 343                     result.push('\n');
 344                 } else if multi_line {
 345                     result.push('\n');
 346                 }
 347                 result.push_str(&indent);
 348             }
 349
 350             result.push_str(&a_str);
 351
 352             if i < attrs.len() -1 {
 353                 result.push('\n');
 354             }
 355         }
 356
 357         result
 358     }
 359
 360     fn format_mod(&mut self, m: &ast::Mod, s: Span, ident: ast::Ident, attrs: &[ast::Attribute]) {
 361         debug!("FmtVisitor::format_mod: ident: {:?}, span: {:?}", ident, s);
 362         // Decide whether this is an inline mod or an external mod.
 363         // There isn't any difference between inline and external mod in AST,
 364         // so we use the trick of searching for an opening brace.
 365         // We can't use the inner span of the mod since it is weird when it
 366         // is empty (no items).
 367         // FIXME Use the inner span once rust-lang/rust#26755 is fixed.
 368         let open_brace = self.codemap.span_to_snippet(s).unwrap().find_uncommented("{");
 369         match open_brace {
 370             None => {
 371                 debug!("FmtVisitor::format_mod: external mod");
 372                 let file_path = self.module_file(ident, attrs, s);
 373                 let filename = file_path.to_str().unwrap();
 374                 if self.changes.is_changed(filename) {
 375                     // The file has already been reformatted, do nothing
 376                 } else {
 377                     self.format_separate_mod(m, filename);
 378                 }
 379                 // TODO Should rewrite properly `mod X;`
 380             }
 381             Some(open_brace) => {
 382                 debug!("FmtVisitor::format_mod: internal mod");
 383                 debug!("... open_brace: {}, str: {:?}", open_brace, self.codemap.span_to_snippet(s));
 384                 // Format everything until opening brace
 385                 // TODO Shoud rewrite properly
 386                 self.format_missing(s.lo + BytePos(open_brace as u32));
 387                 self.block_indent += self.config.tab_spaces;
 388                 visit::walk_mod(self, m);
 389                 debug!("... last_pos after: {:?}", self.last_pos);
 390                 self.block_indent -= self.config.tab_spaces;
 391             }
 392         }
 393         self.format_missing(s.hi);
 394         debug!("FmtVisitor::format_mod: exit");
 395     }
 396
 397     /// Find the file corresponding to an external mod
 398     /// Same algorithm as syntax::parse::eval_src_mod
 399     fn module_file(&self, id: ast::Ident, outer_attrs: &[ast::Attribute], id_sp: Span) -> PathBuf {
 400         // FIXME use libsyntax once rust-lang/rust#26750 is merged
 401         let mut prefix = PathBuf::from(&self.codemap.span_to_filename(id_sp));
 402         prefix.pop();
 403         let mod_string = token::get_ident(id);
 404         match attr::first_attr_value_str_by_name(outer_attrs, "path") {
 405             Some(d) => prefix.join(&*d),
 406             None => {
 407                 let default_path_str = format!("{}.rs", mod_string);
 408                 let secondary_path_str = format!("{}/mod.rs", mod_string);
 409                 let default_path = prefix.join(&default_path_str);
 410                 let secondary_path = prefix.join(&secondary_path_str);
 411                 let default_exists = self.codemap.file_exists(&default_path);
 412                 let secondary_exists = self.codemap.file_exists(&secondary_path);
 413                 if default_exists {
 414                     default_path
 415                 } else if secondary_exists {
 416                     secondary_path
 417                 } else {
 418                     // Should never appens since rustc parsed everything sucessfully
 419                     panic!("Didn't found module {}", mod_string);
 420                 }
 421             }
 422         }
 423     }
 424
 425     /// Format the content of a module into a separate file
 426     fn format_separate_mod(&mut self, m: &ast::Mod, filename: &str) {
 427         let last_pos = self.last_pos;
 428         let block_indent = self.block_indent;
 429         let filemap = self.codemap.get_filemap(filename);
 430         self.last_pos = filemap.start_pos;
 431         self.block_indent = 0;
 432         visit::walk_mod(self, m);
 433         self.format_missing(filemap.end_pos);
 434         self.last_pos = last_pos;
 435         self.block_indent = block_indent;
 436     }
 437 }