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::parse::ParseSess;
  14 use syntax::visit;
  15
  16 use strings::string_buffer::StringBuffer;
  17
  18 use Indent;
  19 use utils;
  20 use config::Config;
  21 use rewrite::{Rewrite, RewriteContext};
  22 use comment::rewrite_comment;
  23 use macros::rewrite_macro;
  24 use items::{rewrite_static, rewrite_associated_static, rewrite_associated_type, rewrite_type_alias, format_impl, format_trait};
  25
  26 pub struct FmtVisitor<'a> {
  27     pub parse_session: &'a ParseSess,
  28     pub codemap: &'a CodeMap,
  29     pub buffer: StringBuffer,
  30     pub last_pos: BytePos,
  31     // FIXME: use an RAII util or closure for indenting
  32     pub block_indent: Indent,
  33     pub config: &'a Config,
  34 }
  35
  36 impl<'a> FmtVisitor<'a> {
  37     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  38         match stmt.node {
  39             ast::StmtKind::Decl(ref decl, _) => {
  40                 if let ast::DeclKind::Item(ref item) = decl.node {
  41                     self.visit_item(item);
  42                 } else {
  43                     let rewrite = stmt.rewrite(&self.get_context(),
  44                                                self.config.max_width - self.block_indent.width(),
  45                                                self.block_indent);
  46
  47                     self.push_rewrite(stmt.span, rewrite);
  48                 }
  49             }
  50             ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
  51                 let rewrite = stmt.rewrite(&self.get_context(),
  52                                            self.config.max_width - self.block_indent.width(),
  53                                            self.block_indent);
  54
  55                 self.push_rewrite(stmt.span, rewrite);
  56             }
  57             ast::StmtKind::Mac(ref mac, _macro_style, _) => {
  58                 self.format_missing_with_indent(stmt.span.lo);
  59                 self.visit_mac(mac);
  60             }
  61         }
  62     }
  63
  64     pub fn visit_block(&mut self, b: &ast::Block) {
  65         debug!("visit_block: {:?} {:?}",
  66                self.codemap.lookup_char_pos(b.span.lo),
  67                self.codemap.lookup_char_pos(b.span.hi));
  68
  69         // Check if this block has braces.
  70         let snippet = self.snippet(b.span);
  71         let has_braces = snippet.starts_with("{") || snippet.starts_with("unsafe");
  72         let brace_compensation = if has_braces {
  73             BytePos(1)
  74         } else {
  75             BytePos(0)
  76         };
  77
  78         self.last_pos = self.last_pos + brace_compensation;
  79         self.block_indent = self.block_indent.block_indent(self.config);
  80         self.buffer.push_str("{");
  81
  82         for stmt in &b.stmts {
  83             self.visit_stmt(&stmt)
  84         }
  85
  86         if let Some(ref e) = b.expr {
  87             self.format_missing_with_indent(e.span.lo);
  88             let rewrite = e.rewrite(&self.get_context(),
  89                                     self.config.max_width - self.block_indent.width(),
  90                                     self.block_indent)
  91                            .unwrap_or_else(|| self.snippet(e.span));
  92
  93             self.buffer.push_str(&rewrite);
  94             self.last_pos = e.span.hi;
  95
  96             if utils::semicolon_for_expr(e) {
  97                 self.buffer.push_str(";");
  98             }
  99         }
 100
 101         // FIXME: we should compress any newlines here to just one
 102         self.format_missing_with_indent(b.span.hi - brace_compensation);
 103         self.close_block();
 104         self.last_pos = b.span.hi;
 105     }
 106
 107     // FIXME: this is a terrible hack to indent the comments between the last
 108     // item in the block and the closing brace to the block's level.
 109     // The closing brace itself, however, should be indented at a shallower
 110     // level.
 111     fn close_block(&mut self) {
 112         let total_len = self.buffer.len;
 113         let chars_too_many = if self.config.hard_tabs {
 114             1
 115         } else {
 116             self.config.tab_spaces
 117         };
 118         self.buffer.truncate(total_len - chars_too_many);
 119         self.buffer.push_str("}");
 120         self.block_indent = self.block_indent.block_unindent(self.config);
 121     }
 122
 123     // Note that this only gets called for function definitions. Required methods
 124     // on traits do not get handled here.
 125     fn visit_fn(&mut self,
 126                 fk: visit::FnKind,
 127                 fd: &ast::FnDecl,
 128                 b: &ast::Block,
 129                 s: Span,
 130                 _: ast::NodeId) {
 131         let indent = self.block_indent;
 132         let rewrite = match fk {
 133             visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
 134                 self.rewrite_fn(indent,
 135                                 ident,
 136                                 fd,
 137                                 None,
 138                                 generics,
 139                                 unsafety,
 140                                 constness,
 141                                 abi,
 142                                 vis,
 143                                 codemap::mk_sp(s.lo, b.span.lo),
 144                                 &b)
 145             }
 146             visit::FnKind::Method(ident, ref sig, vis) => {
 147                 self.rewrite_fn(indent,
 148                                 ident,
 149                                 fd,
 150                                 Some(&sig.explicit_self),
 151                                 &sig.generics,
 152                                 sig.unsafety,
 153                                 sig.constness,
 154                                 sig.abi,
 155                                 vis.unwrap_or(ast::Visibility::Inherited),
 156                                 codemap::mk_sp(s.lo, b.span.lo),
 157                                 &b)
 158             }
 159             visit::FnKind::Closure => None,
 160         };
 161
 162         if let Some(fn_str) = rewrite {
 163             self.format_missing_with_indent(s.lo);
 164             self.buffer.push_str(&fn_str);
 165             if let Some(c) = fn_str.chars().last() {
 166                 if c == '}' {
 167                     self.last_pos = b.span.hi;
 168                     return;
 169                 }
 170             }
 171         } else {
 172             self.format_missing(b.span.lo);
 173         }
 174
 175         self.last_pos = b.span.lo;
 176         self.visit_block(b)
 177     }
 178
 179     fn visit_item(&mut self, item: &ast::Item) {
 180         // Don't look at attributes for modules (except for rustfmt_skip).
 181         // We want to avoid looking at attributes in another file, which the AST
 182         // doesn't distinguish.
 183         // FIXME This is overly conservative and means we miss attributes on
 184         // inline modules.
 185         match item.node {
 186             ast::ItemKind::Mod(_) => {
 187                 if utils::contains_skip(&item.attrs) {
 188                     return;
 189                 }
 190             }
 191             _ => {
 192                 if self.visit_attrs(&item.attrs) {
 193                     self.push_rewrite(item.span, None);
 194                     return;
 195                 }
 196             }
 197         }
 198
 199         match item.node {
 200             ast::ItemKind::Use(ref vp) => {
 201                 self.format_import(item.vis, vp, item.span);
 202             }
 203             ast::ItemKind::Impl(..) => {
 204                 self.format_missing_with_indent(item.span.lo);
 205                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 206                     self.buffer.push_str(&impl_str);
 207                     self.last_pos = item.span.hi;
 208                 }
 209             }
 210             ast::ItemKind::Trait(..) => {
 211                 self.format_missing_with_indent(item.span.lo);
 212                 if let Some(trait_str) = format_trait(&self.get_context(),
 213                                                       item,
 214                                                       self.block_indent) {
 215                     self.buffer.push_str(&trait_str);
 216                     self.last_pos = item.span.hi;
 217                 }
 218             }
 219             ast::ItemKind::ExternCrate(_) => {
 220                 self.format_missing_with_indent(item.span.lo);
 221                 let new_str = self.snippet(item.span);
 222                 self.buffer.push_str(&new_str);
 223                 self.last_pos = item.span.hi;
 224             }
 225             ast::ItemKind::Struct(ref def, ref generics) => {
 226                 let rewrite = {
 227                     let indent = self.block_indent;
 228                     let context = self.get_context();
 229                     ::items::format_struct(&context,
 230                                            "struct ",
 231                                            item.ident,
 232                                            item.vis,
 233                                            def,
 234                                            Some(generics),
 235                                            item.span,
 236                                            indent)
 237                         .map(|s| {
 238                             match *def {
 239                                 ast::VariantData::Tuple(..) => s + ";",
 240                                 _ => s,
 241                             }
 242                         })
 243                 };
 244                 self.push_rewrite(item.span, rewrite);
 245             }
 246             ast::ItemKind::Enum(ref def, ref generics) => {
 247                 self.format_missing_with_indent(item.span.lo);
 248                 self.visit_enum(item.ident, item.vis, def, generics, item.span);
 249                 self.last_pos = item.span.hi;
 250             }
 251             ast::ItemKind::Mod(ref module) => {
 252                 self.format_missing_with_indent(item.span.lo);
 253                 self.format_mod(module, item.vis, item.span, item.ident);
 254             }
 255             ast::ItemKind::Mac(ref mac) => {
 256                 self.format_missing_with_indent(item.span.lo);
 257                 self.visit_mac(mac);
 258             }
 259             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 260                 self.format_missing_with_indent(item.span.lo);
 261                 self.format_foreign_mod(foreign_mod, item.span);
 262             }
 263             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 264                 let rewrite = rewrite_static("static",
 265                                              item.vis,
 266                                              item.ident,
 267                                              ty,
 268                                              mutability,
 269                                              expr,
 270                                              &self.get_context());
 271                 self.push_rewrite(item.span, rewrite);
 272             }
 273             ast::ItemKind::Const(ref ty, ref expr) => {
 274                 let rewrite = rewrite_static("const",
 275                                              item.vis,
 276                                              item.ident,
 277                                              ty,
 278                                              ast::Mutability::Immutable,
 279                                              expr,
 280                                              &self.get_context());
 281                 self.push_rewrite(item.span, rewrite);
 282             }
 283             ast::ItemKind::DefaultImpl(..) => {
 284                 // FIXME(#78): format impl definitions.
 285             }
 286             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 287                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 288                                                     generics,
 289                                                     unsafety,
 290                                                     constness,
 291                                                     abi,
 292                                                     item.vis),
 293                               decl,
 294                               body,
 295                               item.span,
 296                               item.id)
 297             }
 298             ast::ItemKind::Ty(ref ty, ref generics) => {
 299                 let rewrite = rewrite_type_alias(&self.get_context(),
 300                                                  self.block_indent,
 301                                                  item.ident,
 302                                                  ty,
 303                                                  generics,
 304                                                  item.vis,
 305                                                  item.span);
 306                 self.push_rewrite(item.span, rewrite);
 307             }
 308         }
 309     }
 310
 311     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 312         if self.visit_attrs(&ti.attrs) {
 313             return;
 314         }
 315
 316         match ti.node {
 317             ast::TraitItemKind::Const(ref ty, ref expr) => {
 318                 let rewrite = rewrite_associated_static("const",
 319                                              ast::Visibility::Inherited,
 320                                              ti.ident,
 321                                              ty,
 322                                              ast::Mutability::Immutable,
 323                                              expr,
 324                                              &self.get_context());
 325                 self.push_rewrite(ti.span, rewrite);
 326             }
 327             ast::TraitItemKind::Method(ref sig, None) => {
 328                 let indent = self.block_indent;
 329                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 330                 self.push_rewrite(ti.span, rewrite);
 331             }
 332             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 333                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 334                               &sig.decl,
 335                               &body,
 336                               ti.span,
 337                               ti.id);
 338             }
 339             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 340                 let rewrite = rewrite_associated_type("type",
 341                                                       ti.ident,
 342                                                       None,
 343                                                       Some(type_param_bounds),
 344                                                       &self.get_context(),
 345                                                       self.block_indent);
 346                 self.push_rewrite(ti.span, rewrite);
 347             }
 348         }
 349     }
 350
 351     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 352         if self.visit_attrs(&ii.attrs) {
 353             return;
 354         }
 355
 356         match ii.node {
 357             ast::ImplItemKind::Method(ref sig, ref body) => {
 358                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(ii.vis)),
 359                               &sig.decl,
 360                               body,
 361                               ii.span,
 362                               ii.id);
 363             }
 364             ast::ImplItemKind::Const(ref ty, ref expr) => {
 365                 let rewrite = rewrite_static("const",
 366                                              ast::Visibility::Inherited,
 367                                              ii.ident,
 368                                              ty,
 369                                              ast::Mutability::Immutable,
 370                                              &expr,
 371                                              &self.get_context());
 372                 self.push_rewrite(ii.span, rewrite);
 373             }
 374             ast::ImplItemKind::Type(ref ty) => {
 375                 let rewrite = rewrite_associated_type("type",
 376                                                       ii.ident,
 377                                                       Some(ty),
 378                                                       None,
 379                                                       &self.get_context(),
 380                                                       self.block_indent);
 381                 self.push_rewrite(ii.span, rewrite);
 382             }
 383             ast::ImplItemKind::Macro(ref mac) => {
 384                 self.format_missing_with_indent(ii.span.lo);
 385                 self.visit_mac(mac);
 386             }
 387         }
 388     }
 389
 390     fn visit_mac(&mut self, mac: &ast::Mac) {
 391         // 1 = ;
 392         let width = self.config.max_width - self.block_indent.width() - 1;
 393         let rewrite = rewrite_macro(mac, &self.get_context(), width, self.block_indent);
 394
 395         if let Some(res) = rewrite {
 396             self.buffer.push_str(&res);
 397             self.last_pos = mac.span.hi;
 398         }
 399     }
 400
 401     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 402         self.format_missing_with_indent(span.lo);
 403         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 404         self.buffer.push_str(&result);
 405         self.last_pos = span.hi;
 406     }
 407
 408     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 409         FmtVisitor {
 410             parse_session: parse_session,
 411             codemap: parse_session.codemap(),
 412             buffer: StringBuffer::new(),
 413             last_pos: BytePos(0),
 414             block_indent: Indent {
 415                 block_indent: 0,
 416                 alignment: 0,
 417             },
 418             config: config,
 419         }
 420     }
 421
 422     pub fn snippet(&self, span: Span) -> String {
 423         match self.codemap.span_to_snippet(span) {
 424             Ok(s) => s,
 425             Err(_) => {
 426                 println!("Couldn't make snippet for span {:?}->{:?}",
 427                          self.codemap.lookup_char_pos(span.lo),
 428                          self.codemap.lookup_char_pos(span.hi));
 429                 "".to_owned()
 430             }
 431         }
 432     }
 433
 434     // Returns true if we should skip the following item.
 435     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 436         if utils::contains_skip(attrs) {
 437             return true;
 438         }
 439
 440         let outers: Vec<_> = attrs.iter()
 441                                   .filter(|a| a.node.style == ast::AttrStyle::Outer)
 442                                   .cloned()
 443                                   .collect();
 444         if outers.is_empty() {
 445             return false;
 446         }
 447
 448         let first = &outers[0];
 449         self.format_missing_with_indent(first.span.lo);
 450
 451         let rewrite = outers.rewrite(&self.get_context(),
 452                                      self.config.max_width - self.block_indent.width(),
 453                                      self.block_indent)
 454                             .unwrap();
 455         self.buffer.push_str(&rewrite);
 456         let last = outers.last().unwrap();
 457         self.last_pos = last.span.hi;
 458         false
 459     }
 460
 461     fn walk_mod_items(&mut self, m: &ast::Mod) {
 462         for item in &m.items {
 463             self.visit_item(&item);
 464         }
 465     }
 466
 467     fn format_mod(&mut self, m: &ast::Mod, vis: ast::Visibility, s: Span, ident: ast::Ident) {
 468         // Decide whether this is an inline mod or an external mod.
 469         let local_file_name = self.codemap.span_to_filename(s);
 470         let is_internal = local_file_name == self.codemap.span_to_filename(m.inner);
 471
 472         self.buffer.push_str(utils::format_visibility(vis));
 473         self.buffer.push_str("mod ");
 474         self.buffer.push_str(&ident.to_string());
 475
 476         if is_internal {
 477             self.buffer.push_str(" {");
 478             // Hackery to account for the closing }.
 479             let mod_lo = ::utils::span_after(s, "{", self.codemap);
 480             let body_snippet = self.snippet(codemap::mk_sp(mod_lo, m.inner.hi - BytePos(1)));
 481             let body_snippet = body_snippet.trim();
 482             if body_snippet.is_empty() {
 483                 self.buffer.push_str("}");
 484             } else {
 485                 self.last_pos = mod_lo;
 486                 self.block_indent = self.block_indent.block_indent(self.config);
 487                 self.walk_mod_items(m);
 488                 self.format_missing_with_indent(m.inner.hi - BytePos(1));
 489                 self.close_block();
 490             }
 491             self.last_pos = m.inner.hi;
 492         } else {
 493             self.buffer.push_str(";");
 494             self.last_pos = s.hi;
 495         }
 496     }
 497
 498     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 499         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 500         self.last_pos = filemap.start_pos;
 501         self.block_indent = Indent::empty();
 502         self.walk_mod_items(m);
 503         self.format_missing(filemap.end_pos);
 504     }
 505
 506     fn format_import(&mut self, vis: ast::Visibility, vp: &ast::ViewPath, span: Span) {
 507         let vis = utils::format_visibility(vis);
 508         let mut offset = self.block_indent;
 509         offset.alignment += vis.len() + "use ".len();
 510         // 1 = ";"
 511         match vp.rewrite(&self.get_context(),
 512                          self.config.max_width - offset.width() - 1,
 513                          offset) {
 514             Some(ref s) if s.is_empty() => {
 515                 // Format up to last newline
 516                 let prev_span = codemap::mk_sp(self.last_pos, span.lo);
 517                 let span_end = match self.snippet(prev_span).rfind('\n') {
 518                     Some(offset) => self.last_pos + BytePos(offset as u32),
 519                     None => span.lo,
 520                 };
 521                 self.format_missing(span_end);
 522                 self.last_pos = span.hi;
 523             }
 524             Some(ref s) => {
 525                 let s = format!("{}use {};", vis, s);
 526                 self.format_missing_with_indent(span.lo);
 527                 self.buffer.push_str(&s);
 528                 self.last_pos = span.hi;
 529             }
 530             None => {
 531                 self.format_missing_with_indent(span.lo);
 532                 self.format_missing(span.hi);
 533             }
 534         }
 535     }
 536
 537     pub fn get_context(&self) -> RewriteContext {
 538         RewriteContext {
 539             parse_session: self.parse_session,
 540             codemap: self.codemap,
 541             config: self.config,
 542             block_indent: self.block_indent,
 543         }
 544     }
 545 }
 546
 547 impl<'a> Rewrite for [ast::Attribute] {
 548     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 549         let mut result = String::new();
 550         if self.is_empty() {
 551             return Some(result);
 552         }
 553         let indent = offset.to_string(context.config);
 554
 555         for (i, a) in self.iter().enumerate() {
 556             let a_str = context.snippet(a.span);
 557
 558             // Write comments and blank lines between attributes.
 559             if i > 0 {
 560                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 561                 // This particular horror show is to preserve line breaks in between doc
 562                 // comments. An alternative would be to force such line breaks to start
 563                 // with the usual doc comment token.
 564                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 565                 let comment = comment.trim();
 566                 if !comment.is_empty() {
 567                     let comment = try_opt!(rewrite_comment(comment,
 568                                                            false,
 569                                                            context.config.max_width -
 570                                                            offset.width(),
 571                                                            offset,
 572                                                            context.config));
 573                     result.push_str(&indent);
 574                     result.push_str(&comment);
 575                     result.push('\n');
 576                 } else if multi_line {
 577                     result.push('\n');
 578                 }
 579                 result.push_str(&indent);
 580             }
 581
 582             // Write the attribute itself.
 583             result.push_str(&a_str);
 584
 585             if i < self.len() - 1 {
 586                 result.push('\n');
 587             }
 588         }
 589
 590         Some(result)
 591     }
 592 }