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