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, WriteMode};
  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, 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     pub write_mode: Option<WriteMode>,
  35 }
  36
  37 impl<'a> FmtVisitor<'a> {
  38     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  39         match stmt.node {
  40             ast::Stmt_::StmtDecl(ref decl, _) => {
  41                 if let ast::Decl_::DeclItem(ref item) = decl.node {
  42                     self.visit_item(item);
  43                 } else {
  44                     let rewrite = stmt.rewrite(&self.get_context(),
  45                                                self.config.max_width - self.block_indent.width(),
  46                                                self.block_indent);
  47
  48                     self.push_rewrite(stmt.span, rewrite);
  49                 }
  50             }
  51             ast::Stmt_::StmtExpr(..) | ast::Stmt_::StmtSemi(..) => {
  52                 let rewrite = stmt.rewrite(&self.get_context(),
  53                                            self.config.max_width - self.block_indent.width(),
  54                                            self.block_indent);
  55
  56                 self.push_rewrite(stmt.span, rewrite);
  57             }
  58             ast::Stmt_::StmtMac(ref mac, _macro_style) => {
  59                 self.format_missing_with_indent(stmt.span.lo);
  60                 self.visit_mac(mac);
  61             }
  62         }
  63     }
  64
  65     pub fn visit_block(&mut self, b: &ast::Block) {
  66         debug!("visit_block: {:?} {:?}",
  67                self.codemap.lookup_char_pos(b.span.lo),
  68                self.codemap.lookup_char_pos(b.span.hi));
  69
  70         // Check if this block has braces.
  71         let snippet = self.snippet(b.span);
  72         let has_braces = &snippet[..1] == "{" || &snippet[..6] == "unsafe";
  73         let brace_compensation = if has_braces {
  74             BytePos(1)
  75         } else {
  76             BytePos(0)
  77         };
  78
  79         self.last_pos = self.last_pos + brace_compensation;
  80         self.block_indent = self.block_indent.block_indent(self.config);
  81         self.buffer.push_str("{");
  82
  83         for stmt in &b.stmts {
  84             self.visit_stmt(&stmt)
  85         }
  86
  87         if let Some(ref e) = b.expr {
  88             self.format_missing_with_indent(e.span.lo);
  89             let rewrite = e.rewrite(&self.get_context(),
  90                                     self.config.max_width - self.block_indent.width(),
  91                                     self.block_indent)
  92                            .unwrap_or_else(|| self.snippet(e.span));
  93
  94             self.buffer.push_str(&rewrite);
  95             self.last_pos = e.span.hi;
  96
  97             if utils::semicolon_for_expr(e) {
  98                 self.buffer.push_str(";");
  99             }
 100         }
 101
 102         // FIXME: we should compress any newlines here to just one
 103         self.format_missing_with_indent(b.span.hi - brace_compensation);
 104         self.close_block();
 105         self.last_pos = b.span.hi;
 106     }
 107
 108     // FIXME: this is a terrible hack to indent the comments between the last
 109     // item in the block and the closing brace to the block's level.
 110     // The closing brace itself, however, should be indented at a shallower
 111     // level.
 112     fn close_block(&mut self) {
 113         let total_len = self.buffer.len;
 114         let chars_too_many = if self.config.hard_tabs {
 115             1
 116         } else {
 117             self.config.tab_spaces
 118         };
 119         self.buffer.truncate(total_len - chars_too_many);
 120         self.buffer.push_str("}");
 121         self.block_indent = self.block_indent.block_unindent(self.config);
 122     }
 123
 124     // Note that this only gets called for function definitions. Required methods
 125     // on traits do not get handled here.
 126     fn visit_fn(&mut self,
 127                 fk: visit::FnKind,
 128                 fd: &ast::FnDecl,
 129                 b: &ast::Block,
 130                 s: Span,
 131                 _: ast::NodeId) {
 132         let indent = self.block_indent;
 133         let rewrite = match fk {
 134             visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
 135                 self.rewrite_fn(indent,
 136                                 ident,
 137                                 fd,
 138                                 None,
 139                                 generics,
 140                                 unsafety,
 141                                 constness,
 142                                 abi,
 143                                 vis,
 144                                 codemap::mk_sp(s.lo, b.span.lo),
 145                                 &b)
 146             }
 147             visit::FnKind::Method(ident, ref sig, vis) => {
 148                 self.rewrite_fn(indent,
 149                                 ident,
 150                                 fd,
 151                                 Some(&sig.explicit_self),
 152                                 &sig.generics,
 153                                 sig.unsafety,
 154                                 sig.constness,
 155                                 sig.abi,
 156                                 vis.unwrap_or(ast::Visibility::Inherited),
 157                                 codemap::mk_sp(s.lo, b.span.lo),
 158                                 &b)
 159             }
 160             visit::FnKind::Closure => None,
 161         };
 162
 163         if let Some(fn_str) = rewrite {
 164             self.format_missing_with_indent(s.lo);
 165             self.buffer.push_str(&fn_str);
 166             if let Some(c) = fn_str.chars().last() {
 167                 if c == '}' {
 168                     self.last_pos = b.span.hi;
 169                     return;
 170                 }
 171             }
 172         } else {
 173             self.format_missing(b.span.lo);
 174         }
 175
 176         self.last_pos = b.span.lo;
 177         self.visit_block(b)
 178     }
 179
 180     fn visit_item(&mut self, item: &ast::Item) {
 181         // Don't look at attributes for modules (except for rustfmt_skip).
 182         // We want to avoid looking at attributes in another file, which the AST
 183         // doesn't distinguish.
 184         // FIXME This is overly conservative and means we miss attributes on
 185         // inline modules.
 186         match item.node {
 187             ast::Item_::ItemMod(_) => {
 188                 if utils::contains_skip(&item.attrs) {
 189                     return;
 190                 }
 191             }
 192             _ => {
 193                 if self.visit_attrs(&item.attrs) {
 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(..) => {
 256                 self.format_missing_with_indent(item.span.lo);
 257                 let snippet = self.snippet(item.span);
 258                 self.buffer.push_str(&snippet);
 259                 self.last_pos = item.span.hi;
 260                 // FIXME: we cannot format these yet, because of a bad span.
 261                 // See rust lang issue #28424.
 262             }
 263             ast::Item_::ItemForeignMod(ref foreign_mod) => {
 264                 self.format_missing_with_indent(item.span.lo);
 265                 self.format_foreign_mod(foreign_mod, item.span);
 266             }
 267             ast::Item_::ItemStatic(ref ty, mutability, ref expr) => {
 268                 let rewrite = rewrite_static("static",
 269                                              item.vis,
 270                                              item.ident,
 271                                              ty,
 272                                              mutability,
 273                                              expr,
 274                                              &self.get_context());
 275                 self.push_rewrite(item.span, rewrite);
 276             }
 277             ast::Item_::ItemConst(ref ty, ref expr) => {
 278                 let rewrite = rewrite_static("const",
 279                                              item.vis,
 280                                              item.ident,
 281                                              ty,
 282                                              ast::Mutability::MutImmutable,
 283                                              expr,
 284                                              &self.get_context());
 285                 self.push_rewrite(item.span, rewrite);
 286             }
 287             ast::Item_::ItemDefaultImpl(..) => {
 288                 // FIXME(#78): format impl definitions.
 289             }
 290             ast::ItemFn(ref declaration, unsafety, constness, abi, ref generics, ref body) => {
 291                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 292                                                     generics,
 293                                                     unsafety,
 294                                                     constness,
 295                                                     abi,
 296                                                     item.vis),
 297                               declaration,
 298                               body,
 299                               item.span,
 300                               item.id)
 301             }
 302             ast::Item_::ItemTy(..) => {
 303                 // FIXME(#486): format type aliases.
 304             }
 305         }
 306     }
 307
 308     fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 309         if self.visit_attrs(&ti.attrs) {
 310             return;
 311         }
 312
 313         match ti.node {
 314             ast::ConstTraitItem(..) => {
 315                 // FIXME: Implement
 316             }
 317             ast::MethodTraitItem(ref sig, None) => {
 318                 let indent = self.block_indent;
 319                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 320                 self.push_rewrite(ti.span, rewrite);
 321             }
 322             ast::MethodTraitItem(ref sig, Some(ref body)) => {
 323                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 324                               &sig.decl,
 325                               &body,
 326                               ti.span,
 327                               ti.id);
 328             }
 329             ast::TypeTraitItem(..) => {
 330                 // FIXME: Implement
 331             }
 332         }
 333     }
 334
 335     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 336         if self.visit_attrs(&ii.attrs) {
 337             return;
 338         }
 339
 340         match ii.node {
 341             ast::MethodImplItem(ref sig, ref body) => {
 342                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(ii.vis)),
 343                               &sig.decl,
 344                               body,
 345                               ii.span,
 346                               ii.id);
 347             }
 348             ast::ConstImplItem(..) => {
 349                 // FIXME: Implement
 350             }
 351             ast::TypeImplItem(_) => {
 352                 // FIXME: Implement
 353             }
 354             ast::MacImplItem(ref mac) => {
 355                 self.visit_mac(mac);
 356             }
 357         }
 358     }
 359
 360     fn visit_mac(&mut self, mac: &ast::Mac) {
 361         // 1 = ;
 362         let width = self.config.max_width - self.block_indent.width() - 1;
 363         let rewrite = rewrite_macro(mac, &self.get_context(), width, self.block_indent);
 364
 365         if let Some(res) = rewrite {
 366             self.buffer.push_str(&res);
 367             self.last_pos = mac.span.hi;
 368         }
 369     }
 370
 371     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 372         self.format_missing_with_indent(span.lo);
 373
 374         if let Some(res) = rewrite {
 375             self.buffer.push_str(&res);
 376             self.last_pos = span.hi;
 377         }
 378     }
 379
 380     pub fn from_codemap(parse_session: &'a ParseSess,
 381                         config: &'a Config,
 382                         mode: Option<WriteMode>)
 383                         -> FmtVisitor<'a> {
 384         FmtVisitor {
 385             parse_session: parse_session,
 386             codemap: parse_session.codemap(),
 387             buffer: StringBuffer::new(),
 388             last_pos: BytePos(0),
 389             block_indent: Indent {
 390                 block_indent: 0,
 391                 alignment: 0,
 392             },
 393             config: config,
 394             write_mode: mode,
 395         }
 396     }
 397
 398     pub fn snippet(&self, span: Span) -> String {
 399         match self.codemap.span_to_snippet(span) {
 400             Ok(s) => s,
 401             Err(_) => {
 402                 println!("Couldn't make snippet for span {:?}->{:?}",
 403                          self.codemap.lookup_char_pos(span.lo),
 404                          self.codemap.lookup_char_pos(span.hi));
 405                 "".to_owned()
 406             }
 407         }
 408     }
 409
 410     // Returns true if we should skip the following item.
 411     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 412         if utils::contains_skip(attrs) {
 413             return true;
 414         }
 415
 416         let outers: Vec<_> = attrs.iter()
 417                                   .filter(|a| a.node.style == ast::AttrStyle::Outer)
 418                                   .map(|a| a.clone())
 419                                   .collect();
 420         if outers.is_empty() {
 421             return false;
 422         }
 423
 424         let first = &outers[0];
 425         self.format_missing_with_indent(first.span.lo);
 426
 427         let rewrite = outers.rewrite(&self.get_context(),
 428                                      self.config.max_width - self.block_indent.width(),
 429                                      self.block_indent)
 430                             .unwrap();
 431         self.buffer.push_str(&rewrite);
 432         let last = outers.last().unwrap();
 433         self.last_pos = last.span.hi;
 434         false
 435     }
 436
 437     fn walk_mod_items(&mut self, m: &ast::Mod) {
 438         for item in &m.items {
 439             self.visit_item(&item);
 440         }
 441     }
 442
 443     fn format_mod(&mut self, m: &ast::Mod, vis: ast::Visibility, s: Span, ident: ast::Ident) {
 444         // Decide whether this is an inline mod or an external mod.
 445         let local_file_name = self.codemap.span_to_filename(s);
 446         let is_internal = local_file_name == self.codemap.span_to_filename(m.inner);
 447
 448         self.buffer.push_str(utils::format_visibility(vis));
 449         self.buffer.push_str("mod ");
 450         self.buffer.push_str(&ident.to_string());
 451
 452         if is_internal {
 453             self.buffer.push_str(" {");
 454             self.last_pos = ::utils::span_after(s, "{", self.codemap);
 455             self.block_indent = self.block_indent.block_indent(self.config);
 456             self.walk_mod_items(m);
 457             self.format_missing_with_indent(m.inner.hi - BytePos(1));
 458             self.close_block();
 459             self.last_pos = m.inner.hi;
 460         } else {
 461             self.buffer.push_str(";");
 462             self.last_pos = s.hi;
 463         }
 464     }
 465
 466     pub fn format_separate_mod(&mut self, m: &ast::Mod) {
 467         let filemap = self.codemap.lookup_char_pos(m.inner.lo).file;
 468         self.last_pos = filemap.start_pos;
 469         self.block_indent = Indent::empty();
 470         self.walk_mod_items(m);
 471         self.format_missing(filemap.end_pos);
 472     }
 473
 474     fn format_import(&mut self, vis: ast::Visibility, vp: &ast::ViewPath, span: Span) {
 475         let vis = utils::format_visibility(vis);
 476         let mut offset = self.block_indent;
 477         offset.alignment += vis.len() + "use ".len();
 478         // 1 = ";"
 479         match vp.rewrite(&self.get_context(),
 480                          self.config.max_width - offset.width() - 1,
 481                          offset) {
 482             Some(ref s) if s.is_empty() => {
 483                 // Format up to last newline
 484                 let prev_span = codemap::mk_sp(self.last_pos, span.lo);
 485                 let span_end = match self.snippet(prev_span).rfind('\n') {
 486                     Some(offset) => self.last_pos + BytePos(offset as u32),
 487                     None => span.lo,
 488                 };
 489                 self.format_missing(span_end);
 490                 self.last_pos = span.hi;
 491             }
 492             Some(ref s) => {
 493                 let s = format!("{}use {};", vis, s);
 494                 self.format_missing_with_indent(span.lo);
 495                 self.buffer.push_str(&s);
 496                 self.last_pos = span.hi;
 497             }
 498             None => {
 499                 self.format_missing_with_indent(span.lo);
 500                 self.format_missing(span.hi);
 501             }
 502         }
 503     }
 504
 505     pub fn get_context(&self) -> RewriteContext {
 506         RewriteContext {
 507             parse_session: self.parse_session,
 508             codemap: self.codemap,
 509             config: self.config,
 510             block_indent: self.block_indent,
 511         }
 512     }
 513 }
 514
 515 impl<'a> Rewrite for [ast::Attribute] {
 516     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 517         let mut result = String::new();
 518         if self.is_empty() {
 519             return Some(result);
 520         }
 521         let indent = offset.to_string(context.config);
 522
 523         for (i, a) in self.iter().enumerate() {
 524             let a_str = context.snippet(a.span);
 525
 526             if i > 0 {
 527                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 528                 // This particular horror show is to preserve line breaks in between doc
 529                 // comments. An alternative would be to force such line breaks to start
 530                 // with the usual doc comment token.
 531                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 532                 let comment = comment.trim();
 533                 if !comment.is_empty() {
 534                     let comment = try_opt!(rewrite_comment(comment,
 535                                                            false,
 536                                                            context.config.max_width -
 537                                                            offset.width(),
 538                                                            offset,
 539                                                            context.config));
 540                     result.push_str(&indent);
 541                     result.push_str(&comment);
 542                     result.push('\n');
 543                 } else if multi_line {
 544                     result.push('\n');
 545                 }
 546                 result.push_str(&indent);
 547             }
 548
 549             result.push_str(&a_str);
 550
 551             if i < self.len() - 1 {
 552                 result.push('\n');
 553             }
 554         }
 555
 556         Some(result)
 557     }
 558 }