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_type_alias, format_impl};
  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::Stmt_::StmtDecl(ref decl, _) => {
  40                 if let ast::Decl_::DeclItem(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::Stmt_::StmtExpr(..) | ast::Stmt_::StmtSemi(..) => {
  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::Stmt_::StmtMac(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::Item_::ItemMod(_) => {
 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::Item_::ItemUse(ref vp) => {
 201                 self.format_import(item.vis, vp, item.span);
 202             }
 203             ast::Item_::ItemImpl(..) => {
 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             // FIXME(#78): format traits.
 211             ast::Item_::ItemTrait(_, _, _, ref trait_items) => {
 212                 self.format_missing_with_indent(item.span.lo);
 213                 self.block_indent = self.block_indent.block_indent(self.config);
 214                 for item in trait_items {
 215                     self.visit_trait_item(&item);
 216                 }
 217                 self.block_indent = self.block_indent.block_unindent(self.config);
 218             }
 219             ast::Item_::ItemExternCrate(_) => {
 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::Item_::ItemStruct(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::Item_::ItemEnum(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::Item_::ItemMod(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::Item_::ItemMac(ref mac) => {
 256                 self.format_missing_with_indent(item.span.lo);
 257                 self.visit_mac(mac);
 258             }
 259             ast::Item_::ItemForeignMod(ref foreign_mod) => {
 260                 self.format_missing_with_indent(item.span.lo);
 261                 self.format_foreign_mod(foreign_mod, item.span);
 262             }
 263             ast::Item_::ItemStatic(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::Item_::ItemConst(ref ty, ref expr) => {
 274                 let rewrite = rewrite_static("const",
 275                                              item.vis,
 276                                              item.ident,
 277                                              ty,
 278                                              ast::Mutability::MutImmutable,
 279                                              expr,
 280                                              &self.get_context());
 281                 self.push_rewrite(item.span, rewrite);
 282             }
 283             ast::Item_::ItemDefaultImpl(..) => {
 284                 // FIXME(#78): format impl definitions.
 285             }
 286             ast::ItemFn(ref declaration, 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                               declaration,
 294                               body,
 295                               item.span,
 296                               item.id)
 297             }
 298             ast::Item_::ItemTy(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     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::ConstTraitItem(..) => {
 318                 // FIXME: Implement
 319             }
 320             ast::MethodTraitItem(ref sig, None) => {
 321                 let indent = self.block_indent;
 322                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 323                 self.push_rewrite(ti.span, rewrite);
 324             }
 325             ast::MethodTraitItem(ref sig, Some(ref body)) => {
 326                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 327                               &sig.decl,
 328                               &body,
 329                               ti.span,
 330                               ti.id);
 331             }
 332             ast::TypeTraitItem(..) => {
 333                 // FIXME: Implement
 334             }
 335         }
 336     }
 337
 338     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 339         if self.visit_attrs(&ii.attrs) {
 340             return;
 341         }
 342
 343         match ii.node {
 344             ast::ImplItemKind::Method(ref sig, ref body) => {
 345                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(ii.vis)),
 346                               &sig.decl,
 347                               body,
 348                               ii.span,
 349                               ii.id);
 350             }
 351             ast::ImplItemKind::Const(..) => {
 352                 // FIXME: Implement
 353             }
 354             ast::ImplItemKind::Type(_) => {
 355                 // FIXME: Implement
 356             }
 357             ast::ImplItemKind::Macro(ref mac) => {
 358                 self.format_missing_with_indent(ii.span.lo);
 359                 self.visit_mac(mac);
 360             }
 361         }
 362     }
 363
 364     fn visit_mac(&mut self, mac: &ast::Mac) {
 365         // 1 = ;
 366         let width = self.config.max_width - self.block_indent.width() - 1;
 367         let rewrite = rewrite_macro(mac, &self.get_context(), width, self.block_indent);
 368
 369         if let Some(res) = rewrite {
 370             self.buffer.push_str(&res);
 371             self.last_pos = mac.span.hi;
 372         }
 373     }
 374
 375     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 376         self.format_missing_with_indent(span.lo);
 377         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 378         self.buffer.push_str(&result);
 379         self.last_pos = span.hi;
 380     }
 381
 382     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 383         FmtVisitor {
 384             parse_session: parse_session,
 385             codemap: parse_session.codemap(),
 386             buffer: StringBuffer::new(),
 387             last_pos: BytePos(0),
 388             block_indent: Indent {
 389                 block_indent: 0,
 390                 alignment: 0,
 391             },
 392             config: config,
 393         }
 394     }
 395
 396     pub fn snippet(&self, span: Span) -> String {
 397         match self.codemap.span_to_snippet(span) {
 398             Ok(s) => s,
 399             Err(_) => {
 400                 println!("Couldn't make snippet for span {:?}->{:?}",
 401                          self.codemap.lookup_char_pos(span.lo),
 402                          self.codemap.lookup_char_pos(span.hi));
 403                 "".to_owned()
 404             }
 405         }
 406     }
 407
 408     // Returns true if we should skip the following item.
 409     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 410         if utils::contains_skip(attrs) {
 411             return true;
 412         }
 413
 414         let outers: Vec<_> = attrs.iter()
 415                                   .filter(|a| a.node.style == ast::AttrStyle::Outer)
 416                                   .cloned()
 417                                   .collect();
 418         if outers.is_empty() {
 419             return false;
 420         }
 421
 422         let first = &outers[0];
 423         self.format_missing_with_indent(first.span.lo);
 424
 425         let rewrite = outers.rewrite(&self.get_context(),
 426                                      self.config.max_width - self.block_indent.width(),
 427                                      self.block_indent)
 428                             .unwrap();
 429         self.buffer.push_str(&rewrite);
 430         let last = outers.last().unwrap();
 431         self.last_pos = last.span.hi;
 432         false
 433     }
 434
 435     fn walk_mod_items(&mut self, m: &ast::Mod) {
 436         for item in &m.items {
 437             self.visit_item(&item);
 438         }
 439     }
 440
 441     fn format_mod(&mut self, m: &ast::Mod, vis: ast::Visibility, s: Span, ident: ast::Ident) {
 442         // Decide whether this is an inline mod or an external mod.
 443         let local_file_name = self.codemap.span_to_filename(s);
 444         let is_internal = local_file_name == self.codemap.span_to_filename(m.inner);
 445
 446         self.buffer.push_str(utils::format_visibility(vis));
 447         self.buffer.push_str("mod ");
 448         self.buffer.push_str(&ident.to_string());
 449
 450         if is_internal {
 451             self.buffer.push_str(" {");
 452             // Hackery to account for the closing }.
 453             let mod_lo = ::utils::span_after(s, "{", self.codemap);
 454             let body_snippet = self.snippet(codemap::mk_sp(mod_lo, m.inner.hi - BytePos(1)));
 455             let body_snippet = body_snippet.trim();
 456             if body_snippet.is_empty() {
 457                 self.buffer.push_str("}");
 458             } else {
 459                 self.last_pos = mod_lo;
 460                 self.block_indent = self.block_indent.block_indent(self.config);
 461                 self.walk_mod_items(m);
 462                 self.format_missing_with_indent(m.inner.hi - BytePos(1));
 463                 self.close_block();
 464             }
 465             self.last_pos = m.inner.hi;
 466         } else {
 467             self.buffer.push_str(";");
 468             self.last_pos = s.hi;
 469         }
 470     }
 471
 472     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 473         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 474         self.last_pos = filemap.start_pos;
 475         self.block_indent = Indent::empty();
 476         self.walk_mod_items(m);
 477         self.format_missing(filemap.end_pos);
 478     }
 479
 480     fn format_import(&mut self, vis: ast::Visibility, vp: &ast::ViewPath, span: Span) {
 481         let vis = utils::format_visibility(vis);
 482         let mut offset = self.block_indent;
 483         offset.alignment += vis.len() + "use ".len();
 484         // 1 = ";"
 485         match vp.rewrite(&self.get_context(),
 486                          self.config.max_width - offset.width() - 1,
 487                          offset) {
 488             Some(ref s) if s.is_empty() => {
 489                 // Format up to last newline
 490                 let prev_span = codemap::mk_sp(self.last_pos, span.lo);
 491                 let span_end = match self.snippet(prev_span).rfind('\n') {
 492                     Some(offset) => self.last_pos + BytePos(offset as u32),
 493                     None => span.lo,
 494                 };
 495                 self.format_missing(span_end);
 496                 self.last_pos = span.hi;
 497             }
 498             Some(ref s) => {
 499                 let s = format!("{}use {};", vis, s);
 500                 self.format_missing_with_indent(span.lo);
 501                 self.buffer.push_str(&s);
 502                 self.last_pos = span.hi;
 503             }
 504             None => {
 505                 self.format_missing_with_indent(span.lo);
 506                 self.format_missing(span.hi);
 507             }
 508         }
 509     }
 510
 511     pub fn get_context(&self) -> RewriteContext {
 512         RewriteContext {
 513             parse_session: self.parse_session,
 514             codemap: self.codemap,
 515             config: self.config,
 516             block_indent: self.block_indent,
 517         }
 518     }
 519 }
 520
 521 impl<'a> Rewrite for [ast::Attribute] {
 522     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 523         let mut result = String::new();
 524         if self.is_empty() {
 525             return Some(result);
 526         }
 527         let indent = offset.to_string(context.config);
 528
 529         for (i, a) in self.iter().enumerate() {
 530             let a_str = context.snippet(a.span);
 531
 532             // Write comments and blank lines between attributes.
 533             if i > 0 {
 534                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 535                 // This particular horror show is to preserve line breaks in between doc
 536                 // comments. An alternative would be to force such line breaks to start
 537                 // with the usual doc comment token.
 538                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 539                 let comment = comment.trim();
 540                 if !comment.is_empty() {
 541                     let comment = try_opt!(rewrite_comment(comment,
 542                                                            false,
 543                                                            context.config.max_width -
 544                                                            offset.width(),
 545                                                            offset,
 546                                                            context.config));
 547                     result.push_str(&indent);
 548                     result.push_str(&comment);
 549                     result.push('\n');
 550                 } else if multi_line {
 551                     result.push('\n');
 552                 }
 553                 result.push_str(&indent);
 554             }
 555
 556             // Write the attribute itself.
 557             result.push_str(&a_str);
 558
 559             if i < self.len() - 1 {
 560                 result.push('\n');
 561             }
 562         }
 563
 564         Some(result)
 565     }
 566 }