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, visit};
  12 use syntax::codemap::{self, CodeMap, Span, BytePos};
  13 use syntax::parse::ParseSess;
  14
  15 use strings::string_buffer::StringBuffer;
  16
  17 use Indent;
  18 use utils;
  19 use codemap::SpanUtils;
  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_type, rewrite_type_alias, format_impl, format_trait};
  25
  26 // For format_missing and last_pos, need to use the source callsite (if applicable).
  27 // Required as generated code spans aren't guaranteed to follow on from the last span.
  28 macro_rules! source {
  29     ($this:ident, $sp: expr) => {
  30         $this.codemap.source_callsite($sp)
  31     }
  32 }
  33
  34 pub struct FmtVisitor<'a> {
  35     pub parse_session: &'a ParseSess,
  36     pub codemap: &'a CodeMap,
  37     pub buffer: StringBuffer,
  38     pub last_pos: BytePos,
  39     // FIXME: use an RAII util or closure for indenting
  40     pub block_indent: Indent,
  41     pub config: &'a Config,
  42 }
  43
  44 impl<'a> FmtVisitor<'a> {
  45     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  46         debug!("visit_stmt: {:?} {:?}",
  47                self.codemap.lookup_char_pos(stmt.span.lo),
  48                self.codemap.lookup_char_pos(stmt.span.hi));
  49
  50         match stmt.node {
  51             ast::StmtKind::Decl(ref decl, _) => {
  52                 if let ast::DeclKind::Item(ref item) = decl.node {
  53                     self.visit_item(item);
  54                 } else {
  55                     let rewrite = stmt.rewrite(&self.get_context(),
  56                                                self.config.max_width - self.block_indent.width(),
  57                                                self.block_indent);
  58
  59                     self.push_rewrite(stmt.span, rewrite);
  60                 }
  61             }
  62             ast::StmtKind::Expr(..) |
  63             ast::StmtKind::Semi(..) => {
  64                 let rewrite = stmt.rewrite(&self.get_context(),
  65                                            self.config.max_width - self.block_indent.width(),
  66                                            self.block_indent);
  67
  68                 self.push_rewrite(stmt.span, rewrite);
  69             }
  70             ast::StmtKind::Mac(ref mac, _macro_style, _) => {
  71                 self.format_missing_with_indent(source!(self, stmt.span).lo);
  72                 self.visit_mac(mac, None);
  73             }
  74         }
  75     }
  76
  77     pub fn visit_block(&mut self, b: &ast::Block) {
  78         debug!("visit_block: {:?} {:?}",
  79                self.codemap.lookup_char_pos(b.span.lo),
  80                self.codemap.lookup_char_pos(b.span.hi));
  81
  82         // Check if this block has braces.
  83         let snippet = self.snippet(b.span);
  84         let has_braces = snippet.starts_with("{") || snippet.starts_with("unsafe");
  85         let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
  86
  87         self.last_pos = self.last_pos + brace_compensation;
  88         self.block_indent = self.block_indent.block_indent(self.config);
  89         self.buffer.push_str("{");
  90
  91         for stmt in &b.stmts {
  92             self.visit_stmt(&stmt)
  93         }
  94
  95         if let Some(ref e) = b.expr {
  96             self.format_missing_with_indent(source!(self, e.span).lo);
  97             let rewrite = e.rewrite(&self.get_context(),
  98                          self.config.max_width - self.block_indent.width(),
  99                          self.block_indent)
 100                 .unwrap_or_else(|| self.snippet(e.span));
 101
 102             self.buffer.push_str(&rewrite);
 103             self.last_pos = source!(self, e.span).hi;
 104
 105             if utils::semicolon_for_expr(e) {
 106                 self.buffer.push_str(";");
 107             }
 108         }
 109
 110         // FIXME: we should compress any newlines here to just one
 111         self.format_missing_with_indent(source!(self, b.span).hi - brace_compensation);
 112         self.close_block();
 113         self.last_pos = source!(self, b.span).hi;
 114     }
 115
 116     // FIXME: this is a terrible hack to indent the comments between the last
 117     // item in the block and the closing brace to the block's level.
 118     // The closing brace itself, however, should be indented at a shallower
 119     // level.
 120     fn close_block(&mut self) {
 121         let total_len = self.buffer.len;
 122         let chars_too_many = if self.config.hard_tabs {
 123             1
 124         } else {
 125             self.config.tab_spaces
 126         };
 127         self.buffer.truncate(total_len - chars_too_many);
 128         self.buffer.push_str("}");
 129         self.block_indent = self.block_indent.block_unindent(self.config);
 130     }
 131
 132     // Note that this only gets called for function definitions. Required methods
 133     // on traits do not get handled here.
 134     fn visit_fn(&mut self,
 135                 fk: visit::FnKind,
 136                 fd: &ast::FnDecl,
 137                 b: &ast::Block,
 138                 s: Span,
 139                 _: ast::NodeId) {
 140         let indent = self.block_indent;
 141         let rewrite = match fk {
 142             visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
 143                 self.rewrite_fn(indent,
 144                                 ident,
 145                                 fd,
 146                                 generics,
 147                                 unsafety,
 148                                 constness,
 149                                 abi,
 150                                 vis,
 151                                 codemap::mk_sp(s.lo, b.span.lo),
 152                                 &b)
 153             }
 154             visit::FnKind::Method(ident, ref sig, vis) => {
 155                 self.rewrite_fn(indent,
 156                                 ident,
 157                                 fd,
 158                                 &sig.generics,
 159                                 sig.unsafety,
 160                                 sig.constness,
 161                                 sig.abi,
 162                                 vis.unwrap_or(&ast::Visibility::Inherited),
 163                                 codemap::mk_sp(s.lo, b.span.lo),
 164                                 &b)
 165             }
 166             visit::FnKind::Closure => None,
 167         };
 168
 169         if let Some(fn_str) = rewrite {
 170             self.format_missing_with_indent(source!(self, s).lo);
 171             self.buffer.push_str(&fn_str);
 172             if let Some(c) = fn_str.chars().last() {
 173                 if c == '}' {
 174                     self.last_pos = source!(self, b.span).hi;
 175                     return;
 176                 }
 177             }
 178         } else {
 179             self.format_missing(source!(self, b.span).lo);
 180         }
 181
 182         self.last_pos = source!(self, b.span).lo;
 183         self.visit_block(b)
 184     }
 185
 186     fn visit_item(&mut self, item: &ast::Item) {
 187         // This is where we bail out if there is a skip attribute. This is only
 188         // complex in the module case. It is complex because the module could be
 189         // in a seperate file and there might be attributes in both files, but
 190         // the AST lumps them all together.
 191         match item.node {
 192             ast::ItemKind::Mod(ref m) => {
 193                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 194                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 195                 if outer_file.name == inner_file.name {
 196                     // Module is inline, in this case we treat modules like any
 197                     // other item.
 198                     if self.visit_attrs(&item.attrs) {
 199                         self.push_rewrite(item.span, None);
 200                         return;
 201                     }
 202                 } else if utils::contains_skip(&item.attrs) {
 203                     // Module is not inline, but should be skipped.
 204                     return;
 205                 } else {
 206                     // Module is not inline and should not be skipped. We want
 207                     // to process only the attributes in the current file.
 208                     let attrs = item.attrs
 209                         .iter()
 210                         .filter_map(|a| {
 211                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 212                             if attr_file.name == outer_file.name {
 213                                 Some(a.clone())
 214                             } else {
 215                                 None
 216                             }
 217                         })
 218                         .collect::<Vec<_>>();
 219                     // Assert because if we should skip it should be caught by
 220                     // the above case.
 221                     assert!(!self.visit_attrs(&attrs));
 222                 }
 223             }
 224             _ => {
 225                 if self.visit_attrs(&item.attrs) {
 226                     self.push_rewrite(item.span, None);
 227                     return;
 228                 }
 229             }
 230         }
 231
 232         match item.node {
 233             ast::ItemKind::Use(ref vp) => {
 234                 self.format_import(&item.vis, vp, item.span);
 235             }
 236             ast::ItemKind::Impl(..) => {
 237                 self.format_missing_with_indent(source!(self, item.span).lo);
 238                 if let Some(impl_str) = format_impl(&self.get_context(), item, self.block_indent) {
 239                     self.buffer.push_str(&impl_str);
 240                     self.last_pos = source!(self, item.span).hi;
 241                 }
 242             }
 243             ast::ItemKind::Trait(..) => {
 244                 self.format_missing_with_indent(item.span.lo);
 245                 if let Some(trait_str) = format_trait(&self.get_context(),
 246                                                       item,
 247                                                       self.block_indent) {
 248                     self.buffer.push_str(&trait_str);
 249                     self.last_pos = source!(self, item.span).hi;
 250                 }
 251             }
 252             ast::ItemKind::ExternCrate(_) => {
 253                 self.format_missing_with_indent(source!(self, item.span).lo);
 254                 let new_str = self.snippet(item.span);
 255                 self.buffer.push_str(&new_str);
 256                 self.last_pos = source!(self, item.span).hi;
 257             }
 258             ast::ItemKind::Struct(ref def, ref generics) => {
 259                 let rewrite = {
 260                     let indent = self.block_indent;
 261                     let context = self.get_context();
 262                     ::items::format_struct(&context,
 263                                            "struct ",
 264                                            item.ident,
 265                                            &item.vis,
 266                                            def,
 267                                            Some(generics),
 268                                            item.span,
 269                                            indent,
 270                                            None)
 271                         .map(|s| {
 272                             match *def {
 273                                 ast::VariantData::Tuple(..) => s + ";",
 274                                 _ => s,
 275                             }
 276                         })
 277                 };
 278                 self.push_rewrite(item.span, rewrite);
 279             }
 280             ast::ItemKind::Enum(ref def, ref generics) => {
 281                 self.format_missing_with_indent(source!(self, item.span).lo);
 282                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 283                 self.last_pos = source!(self, item.span).hi;
 284             }
 285             ast::ItemKind::Mod(ref module) => {
 286                 self.format_missing_with_indent(source!(self, item.span).lo);
 287                 self.format_mod(module, &item.vis, item.span, item.ident);
 288             }
 289             ast::ItemKind::Mac(ref mac) => {
 290                 self.format_missing_with_indent(source!(self, item.span).lo);
 291                 self.visit_mac(mac, Some(item.ident));
 292             }
 293             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 294                 self.format_missing_with_indent(source!(self, item.span).lo);
 295                 self.format_foreign_mod(foreign_mod, item.span);
 296             }
 297             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 298                 let rewrite = rewrite_static("static",
 299                                              &item.vis,
 300                                              item.ident,
 301                                              ty,
 302                                              mutability,
 303                                              Some(expr),
 304                                              &self.get_context());
 305                 self.push_rewrite(item.span, rewrite);
 306             }
 307             ast::ItemKind::Const(ref ty, ref expr) => {
 308                 let rewrite = rewrite_static("const",
 309                                              &item.vis,
 310                                              item.ident,
 311                                              ty,
 312                                              ast::Mutability::Immutable,
 313                                              Some(expr),
 314                                              &self.get_context());
 315                 self.push_rewrite(item.span, rewrite);
 316             }
 317             ast::ItemKind::DefaultImpl(..) => {
 318                 // FIXME(#78): format impl definitions.
 319             }
 320             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 321                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 322                                                     generics,
 323                                                     unsafety,
 324                                                     constness,
 325                                                     abi,
 326                                                     &item.vis),
 327                               decl,
 328                               body,
 329                               item.span,
 330                               item.id)
 331             }
 332             ast::ItemKind::Ty(ref ty, ref generics) => {
 333                 let rewrite = rewrite_type_alias(&self.get_context(),
 334                                                  self.block_indent,
 335                                                  item.ident,
 336                                                  ty,
 337                                                  generics,
 338                                                  &item.vis,
 339                                                  item.span);
 340                 self.push_rewrite(item.span, rewrite);
 341             }
 342         }
 343     }
 344
 345     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 346         if self.visit_attrs(&ti.attrs) {
 347             return;
 348         }
 349
 350         match ti.node {
 351             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 352                 let rewrite = rewrite_static("const",
 353                                              &ast::Visibility::Inherited,
 354                                              ti.ident,
 355                                              ty,
 356                                              ast::Mutability::Immutable,
 357                                              expr_opt.as_ref(),
 358                                              &self.get_context());
 359                 self.push_rewrite(ti.span, rewrite);
 360             }
 361             ast::TraitItemKind::Method(ref sig, None) => {
 362                 let indent = self.block_indent;
 363                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 364                 self.push_rewrite(ti.span, rewrite);
 365             }
 366             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 367                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 368                               &sig.decl,
 369                               &body,
 370                               ti.span,
 371                               ti.id);
 372             }
 373             ast::TraitItemKind::Type(ref type_param_bounds, _) => {
 374                 let rewrite = rewrite_associated_type(ti.ident,
 375                                                       None,
 376                                                       Some(type_param_bounds),
 377                                                       &self.get_context(),
 378                                                       self.block_indent);
 379                 self.push_rewrite(ti.span, rewrite);
 380             }
 381         }
 382     }
 383
 384     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 385         if self.visit_attrs(&ii.attrs) {
 386             return;
 387         }
 388
 389         match ii.node {
 390             ast::ImplItemKind::Method(ref sig, ref body) => {
 391                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(&ii.vis)),
 392                               &sig.decl,
 393                               body,
 394                               ii.span,
 395                               ii.id);
 396             }
 397             ast::ImplItemKind::Const(ref ty, ref expr) => {
 398                 let rewrite = rewrite_static("const",
 399                                              &ii.vis,
 400                                              ii.ident,
 401                                              ty,
 402                                              ast::Mutability::Immutable,
 403                                              Some(expr),
 404                                              &self.get_context());
 405                 self.push_rewrite(ii.span, rewrite);
 406             }
 407             ast::ImplItemKind::Type(ref ty) => {
 408                 let rewrite = rewrite_associated_type(ii.ident,
 409                                                       Some(ty),
 410                                                       None,
 411                                                       &self.get_context(),
 412                                                       self.block_indent);
 413                 self.push_rewrite(ii.span, rewrite);
 414             }
 415             ast::ImplItemKind::Macro(ref mac) => {
 416                 self.format_missing_with_indent(source!(self, ii.span).lo);
 417                 self.visit_mac(mac, Some(ii.ident));
 418             }
 419         }
 420     }
 421
 422     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>) {
 423         // 1 = ;
 424         let width = self.config.max_width - self.block_indent.width() - 1;
 425         let rewrite = rewrite_macro(mac, ident, &self.get_context(), width, self.block_indent);
 426
 427         if let Some(res) = rewrite {
 428             self.buffer.push_str(&res);
 429             self.last_pos = source!(self, mac.span).hi;
 430         }
 431     }
 432
 433     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 434         self.format_missing_with_indent(source!(self, span).lo);
 435         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 436         self.buffer.push_str(&result);
 437         self.last_pos = source!(self, span).hi;
 438     }
 439
 440     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 441         FmtVisitor {
 442             parse_session: parse_session,
 443             codemap: parse_session.codemap(),
 444             buffer: StringBuffer::new(),
 445             last_pos: BytePos(0),
 446             block_indent: Indent {
 447                 block_indent: 0,
 448                 alignment: 0,
 449             },
 450             config: config,
 451         }
 452     }
 453
 454     pub fn snippet(&self, span: Span) -> String {
 455         match self.codemap.span_to_snippet(span) {
 456             Ok(s) => s,
 457             Err(_) => {
 458                 println!("Couldn't make snippet for span {:?}->{:?}",
 459                          self.codemap.lookup_char_pos(span.lo),
 460                          self.codemap.lookup_char_pos(span.hi));
 461                 "".to_owned()
 462             }
 463         }
 464     }
 465
 466     // Returns true if we should skip the following item.
 467     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 468         if utils::contains_skip(attrs) {
 469             return true;
 470         }
 471
 472         let outers: Vec<_> = attrs.iter()
 473             .filter(|a| a.node.style == ast::AttrStyle::Outer)
 474             .cloned()
 475             .collect();
 476         if outers.is_empty() {
 477             return false;
 478         }
 479
 480         let first = &outers[0];
 481         self.format_missing_with_indent(source!(self, first.span).lo);
 482
 483         let rewrite = outers.rewrite(&self.get_context(),
 484                      self.config.max_width - self.block_indent.width(),
 485                      self.block_indent)
 486             .unwrap();
 487         self.buffer.push_str(&rewrite);
 488         let last = outers.last().unwrap();
 489         self.last_pos = source!(self, last.span).hi;
 490         false
 491     }
 492
 493     fn walk_mod_items(&mut self, m: &ast::Mod) {
 494         for item in &m.items {
 495             self.visit_item(&item);
 496         }
 497     }
 498
 499     fn format_mod(&mut self, m: &ast::Mod, vis: &ast::Visibility, s: Span, ident: ast::Ident) {
 500         // Decide whether this is an inline mod or an external mod.
 501         let local_file_name = self.codemap.span_to_filename(s);
 502         let is_internal = local_file_name == self.codemap.span_to_filename(source!(self, m.inner));
 503
 504         self.buffer.push_str(&*utils::format_visibility(vis));
 505         self.buffer.push_str("mod ");
 506         self.buffer.push_str(&ident.to_string());
 507
 508         if is_internal {
 509             self.buffer.push_str(" {");
 510             // Hackery to account for the closing }.
 511             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 512             let body_snippet =
 513                 self.snippet(codemap::mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 514             let body_snippet = body_snippet.trim();
 515             if body_snippet.is_empty() {
 516                 self.buffer.push_str("}");
 517             } else {
 518                 self.last_pos = mod_lo;
 519                 self.block_indent = self.block_indent.block_indent(self.config);
 520                 self.walk_mod_items(m);
 521                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 522                 self.close_block();
 523             }
 524             self.last_pos = source!(self, m.inner).hi;
 525         } else {
 526             self.buffer.push_str(";");
 527             self.last_pos = source!(self, s).hi;
 528         }
 529     }
 530
 531     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 532         let filemap = self.codemap.lookup_char_pos(source!(self, m.inner).lo).file;
 533         self.last_pos = filemap.start_pos;
 534         self.block_indent = Indent::empty();
 535         self.walk_mod_items(m);
 536         self.format_missing(filemap.end_pos);
 537     }
 538
 539     fn format_import(&mut self, vis: &ast::Visibility, vp: &ast::ViewPath, span: Span) {
 540         let vis = utils::format_visibility(vis);
 541         let mut offset = self.block_indent;
 542         offset.alignment += vis.len() + "use ".len();
 543         // 1 = ";"
 544         match vp.rewrite(&self.get_context(),
 545                          self.config.max_width - offset.width() - 1,
 546                          offset) {
 547             Some(ref s) if s.is_empty() => {
 548                 // Format up to last newline
 549                 let prev_span = codemap::mk_sp(self.last_pos, source!(self, span).lo);
 550                 let span_end = match self.snippet(prev_span).rfind('\n') {
 551                     Some(offset) => self.last_pos + BytePos(offset as u32),
 552                     None => source!(self, span).lo,
 553                 };
 554                 self.format_missing(span_end);
 555                 self.last_pos = source!(self, span).hi;
 556             }
 557             Some(ref s) => {
 558                 let s = format!("{}use {};", vis, s);
 559                 self.format_missing_with_indent(source!(self, span).lo);
 560                 self.buffer.push_str(&s);
 561                 self.last_pos = source!(self, span).hi;
 562             }
 563             None => {
 564                 self.format_missing_with_indent(source!(self, span).lo);
 565                 self.format_missing(source!(self, span).hi);
 566             }
 567         }
 568     }
 569
 570     pub fn get_context(&self) -> RewriteContext {
 571         RewriteContext {
 572             parse_session: self.parse_session,
 573             codemap: self.codemap,
 574             config: self.config,
 575             block_indent: self.block_indent,
 576         }
 577     }
 578 }
 579
 580 impl<'a> Rewrite for [ast::Attribute] {
 581     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 582         let mut result = String::new();
 583         if self.is_empty() {
 584             return Some(result);
 585         }
 586         let indent = offset.to_string(context.config);
 587
 588         for (i, a) in self.iter().enumerate() {
 589             let mut a_str = context.snippet(a.span);
 590
 591             // Write comments and blank lines between attributes.
 592             if i > 0 {
 593                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 594                 // This particular horror show is to preserve line breaks in between doc
 595                 // comments. An alternative would be to force such line breaks to start
 596                 // with the usual doc comment token.
 597                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 598                 let comment = comment.trim();
 599                 if !comment.is_empty() {
 600                     let comment = try_opt!(rewrite_comment(comment,
 601                                                            false,
 602                                                            context.config.ideal_width -
 603                                                            offset.width(),
 604                                                            offset,
 605                                                            context.config));
 606                     result.push_str(&indent);
 607                     result.push_str(&comment);
 608                     result.push('\n');
 609                 } else if multi_line {
 610                     result.push('\n');
 611                 }
 612                 result.push_str(&indent);
 613             }
 614
 615             if a_str.starts_with("//") {
 616                 a_str = try_opt!(rewrite_comment(&a_str,
 617                                                  false,
 618                                                  context.config.ideal_width - offset.width(),
 619                                                  offset,
 620                                                  context.config));
 621             }
 622
 623             // Write the attribute itself.
 624             result.push_str(&a_str);
 625
 626             if i < self.len() - 1 {
 627                 result.push('\n');
 628             }
 629         }
 630
 631         Some(result)
 632     }
 633 }