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;
  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     // TODO: RAII util 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         // TODO: we should compress any newlines here to just one
 103         self.format_missing_with_indent(b.span.hi - brace_compensation);
 104         // FIXME: this is a terrible hack to indent the comments between the last
 105         // item in the block and the closing brace to the block's level.
 106         // The closing brace itself, however, should be indented at a shallower
 107         // level.
 108         let total_len = self.buffer.len;
 109         let chars_too_many = if self.config.hard_tabs {
 110             1
 111         } else {
 112             self.config.tab_spaces
 113         };
 114         self.buffer.truncate(total_len - chars_too_many);
 115         self.buffer.push_str("}");
 116         self.last_pos = b.span.hi;
 117         self.block_indent = self.block_indent.block_unindent(self.config);
 118     }
 119
 120     // Note that this only gets called for function definitions. Required methods
 121     // on traits do not get handled here.
 122     fn visit_fn(&mut self,
 123                 fk: visit::FnKind,
 124                 fd: &ast::FnDecl,
 125                 b: &ast::Block,
 126                 s: Span,
 127                 _: ast::NodeId) {
 128         let indent = self.block_indent;
 129         let rewrite = match fk {
 130             visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
 131                 self.rewrite_fn(indent,
 132                                 ident,
 133                                 fd,
 134                                 None,
 135                                 generics,
 136                                 unsafety,
 137                                 constness,
 138                                 abi,
 139                                 vis,
 140                                 codemap::mk_sp(s.lo, b.span.lo))
 141             }
 142             visit::FnKind::Method(ident, ref sig, vis) => {
 143                 self.rewrite_fn(indent,
 144                                 ident,
 145                                 fd,
 146                                 Some(&sig.explicit_self),
 147                                 &sig.generics,
 148                                 sig.unsafety,
 149                                 sig.constness,
 150                                 sig.abi,
 151                                 vis.unwrap_or(ast::Visibility::Inherited),
 152                                 codemap::mk_sp(s.lo, b.span.lo))
 153             }
 154             visit::FnKind::Closure => None,
 155         };
 156
 157         if let Some(ref single_line_fn) = self.rewrite_single_line_fn(&rewrite, &b) {
 158             self.format_missing_with_indent(s.lo);
 159             self.buffer.push_str(single_line_fn);
 160             self.last_pos = b.span.hi;
 161             return;
 162         }
 163
 164         if let Some(fn_str) = rewrite {
 165             self.format_missing_with_indent(s.lo);
 166             self.buffer.push_str(&fn_str);
 167         } else {
 168             self.format_missing(b.span.lo);
 169         }
 170
 171         self.last_pos = b.span.lo;
 172         self.visit_block(b)
 173     }
 174
 175     fn visit_item(&mut self, item: &ast::Item) {
 176         // Don't look at attributes for modules.
 177         // We want to avoid looking at attributes in another file, which the AST
 178         // doesn't distinguish. FIXME This is overly conservative and means we miss
 179         // attributes on inline modules.
 180         match item.node {
 181             ast::Item_::ItemMod(_) => {}
 182             _ => {
 183                 if self.visit_attrs(&item.attrs) {
 184                     return;
 185                 }
 186             }
 187         }
 188
 189         match item.node {
 190             ast::Item_::ItemUse(ref vp) => {
 191                 self.format_import(item.vis, vp, item.span);
 192             }
 193             // FIXME(#78): format impl definitions.
 194             ast::Item_::ItemImpl(_, _, _, _, _, ref impl_items) => {
 195                 self.format_missing_with_indent(item.span.lo);
 196                 self.block_indent = self.block_indent.block_indent(self.config);
 197                 for item in impl_items {
 198                     self.visit_impl_item(&item);
 199                 }
 200                 self.block_indent = self.block_indent.block_unindent(self.config);
 201             }
 202             // FIXME(#78): format traits.
 203             ast::Item_::ItemTrait(_, _, _, ref trait_items) => {
 204                 self.format_missing_with_indent(item.span.lo);
 205                 self.block_indent = self.block_indent.block_indent(self.config);
 206                 for item in trait_items {
 207                     self.visit_trait_item(&item);
 208                 }
 209                 self.block_indent = self.block_indent.block_unindent(self.config);
 210             }
 211             ast::Item_::ItemExternCrate(_) => {
 212                 self.format_missing_with_indent(item.span.lo);
 213                 let new_str = self.snippet(item.span);
 214                 self.buffer.push_str(&new_str);
 215                 self.last_pos = item.span.hi;
 216             }
 217             ast::Item_::ItemStruct(ref def, ref generics) => {
 218                 let indent = self.block_indent;
 219                 let rewrite = self.format_struct("struct ",
 220                                                  item.ident,
 221                                                  item.vis,
 222                                                  def,
 223                                                  Some(generics),
 224                                                  item.span,
 225                                                  indent)
 226                                   .map(|s| {
 227                                       match *def {
 228                                           ast::VariantData::Tuple(..) => s + ";",
 229                                           _ => s,
 230                                       }
 231                                   });
 232                 self.push_rewrite(item.span, rewrite);
 233             }
 234             ast::Item_::ItemEnum(ref def, ref generics) => {
 235                 self.format_missing_with_indent(item.span.lo);
 236                 self.visit_enum(item.ident, item.vis, def, generics, item.span);
 237                 self.last_pos = item.span.hi;
 238             }
 239             ast::Item_::ItemMod(ref module) => {
 240                 self.format_missing_with_indent(item.span.lo);
 241                 self.format_mod(module, item.span, item.ident);
 242             }
 243             ast::Item_::ItemMac(..) => {
 244                 self.format_missing_with_indent(item.span.lo);
 245                 let snippet = self.snippet(item.span);
 246                 self.buffer.push_str(&snippet);
 247                 self.last_pos = item.span.hi;
 248                 // FIXME: we cannot format these yet, because of a bad span.
 249                 // See rust lang issue #28424.
 250             }
 251             ast::Item_::ItemForeignMod(ref foreign_mod) => {
 252                 self.format_missing_with_indent(item.span.lo);
 253                 self.format_foreign_mod(foreign_mod, item.span);
 254             }
 255             ast::Item_::ItemStatic(ref ty, mutability, ref expr) => {
 256                 let rewrite = rewrite_static("static",
 257                                              item.vis,
 258                                              item.ident,
 259                                              ty,
 260                                              mutability,
 261                                              expr,
 262                                              &self.get_context());
 263                 self.push_rewrite(item.span, rewrite);
 264             }
 265             ast::Item_::ItemConst(ref ty, ref expr) => {
 266                 let rewrite = rewrite_static("const",
 267                                              item.vis,
 268                                              item.ident,
 269                                              ty,
 270                                              ast::Mutability::MutImmutable,
 271                                              expr,
 272                                              &self.get_context());
 273                 self.push_rewrite(item.span, rewrite);
 274             }
 275             ast::Item_::ItemDefaultImpl(..) => {
 276                 // FIXME(#78): format impl definitions.
 277             }
 278             ast::ItemFn(ref declaration, unsafety, constness, abi, ref generics, ref body) => {
 279                 self.visit_fn(visit::FnKind::ItemFn(item.ident,
 280                                                     generics,
 281                                                     unsafety,
 282                                                     constness,
 283                                                     abi,
 284                                                     item.vis),
 285                               declaration,
 286                               body,
 287                               item.span,
 288                               item.id)
 289             }
 290             ast::Item_::ItemTy(..) => {
 291                 // FIXME(#486): format type aliases.
 292             }
 293         }
 294     }
 295
 296     fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 297         if self.visit_attrs(&ti.attrs) {
 298             return;
 299         }
 300
 301         match ti.node {
 302             ast::ConstTraitItem(..) => {
 303                 // FIXME: Implement
 304             }
 305             ast::MethodTraitItem(ref sig, None) => {
 306                 let indent = self.block_indent;
 307                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 308                 self.push_rewrite(ti.span, rewrite);
 309             }
 310             ast::MethodTraitItem(ref sig, Some(ref body)) => {
 311                 self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
 312                               &sig.decl,
 313                               &body,
 314                               ti.span,
 315                               ti.id);
 316             }
 317             ast::TypeTraitItem(..) => {
 318                 // FIXME: Implement
 319             }
 320         }
 321     }
 322
 323     fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 324         if self.visit_attrs(&ii.attrs) {
 325             return;
 326         }
 327
 328         match ii.node {
 329             ast::MethodImplItem(ref sig, ref body) => {
 330                 self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(ii.vis)),
 331                               &sig.decl,
 332                               body,
 333                               ii.span,
 334                               ii.id);
 335             }
 336             ast::ConstImplItem(..) => {
 337                 // FIXME: Implement
 338             }
 339             ast::TypeImplItem(_) => {
 340                 // FIXME: Implement
 341             }
 342             ast::MacImplItem(ref mac) => {
 343                 self.visit_mac(mac);
 344             }
 345         }
 346     }
 347
 348     fn visit_mac(&mut self, mac: &ast::Mac) {
 349         // 1 = ;
 350         let width = self.config.max_width - self.block_indent.width() - 1;
 351         let rewrite = rewrite_macro(mac, &self.get_context(), width, self.block_indent);
 352
 353         if let Some(res) = rewrite {
 354             self.buffer.push_str(&res);
 355             self.last_pos = mac.span.hi;
 356         }
 357     }
 358
 359     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 360         self.format_missing_with_indent(span.lo);
 361
 362         if let Some(res) = rewrite {
 363             self.buffer.push_str(&res);
 364             self.last_pos = span.hi;
 365         }
 366     }
 367
 368     pub fn from_codemap(parse_session: &'a ParseSess,
 369                         config: &'a Config,
 370                         mode: Option<WriteMode>)
 371                         -> FmtVisitor<'a> {
 372         FmtVisitor {
 373             parse_session: parse_session,
 374             codemap: parse_session.codemap(),
 375             buffer: StringBuffer::new(),
 376             last_pos: BytePos(0),
 377             block_indent: Indent {
 378                 block_indent: 0,
 379                 alignment: 0,
 380             },
 381             config: config,
 382             write_mode: mode,
 383         }
 384     }
 385
 386     pub fn snippet(&self, span: Span) -> String {
 387         match self.codemap.span_to_snippet(span) {
 388             Ok(s) => s,
 389             Err(_) => {
 390                 println!("Couldn't make snippet for span {:?}->{:?}",
 391                          self.codemap.lookup_char_pos(span.lo),
 392                          self.codemap.lookup_char_pos(span.hi));
 393                 "".to_owned()
 394             }
 395         }
 396     }
 397
 398     // Returns true if we should skip the following item.
 399     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 400         if attrs.is_empty() {
 401             return false;
 402         }
 403
 404         if utils::contains_skip(attrs) {
 405             return true;
 406         }
 407
 408         let outers: Vec<_> = attrs.iter()
 409                                   .filter(|a| a.node.style == ast::AttrStyle::Outer)
 410                                   .map(|a| a.clone())
 411                                   .collect();
 412         if outers.is_empty() {
 413             return false;
 414         }
 415
 416         let first = &outers[0];
 417         self.format_missing_with_indent(first.span.lo);
 418
 419         let rewrite = outers.rewrite(&self.get_context(),
 420                                      self.config.max_width - self.block_indent.width(),
 421                                      self.block_indent)
 422                             .unwrap();
 423         self.buffer.push_str(&rewrite);
 424         let last = outers.last().unwrap();
 425         self.last_pos = last.span.hi;
 426         false
 427     }
 428
 429     fn walk_mod_items(&mut self, m: &ast::Mod) {
 430         for item in &m.items {
 431             self.visit_item(&item);
 432         }
 433     }
 434
 435     fn format_mod(&mut self, m: &ast::Mod, s: Span, ident: ast::Ident) {
 436         debug!("FmtVisitor::format_mod: ident: {:?}, span: {:?}", ident, s);
 437
 438         // Decide whether this is an inline mod or an external mod.
 439         let local_file_name = self.codemap.span_to_filename(s);
 440         let is_internal = local_file_name == self.codemap.span_to_filename(m.inner);
 441
 442         // TODO: Should rewrite properly `mod X;`
 443
 444         if is_internal {
 445             self.block_indent = self.block_indent.block_indent(self.config);
 446             self.walk_mod_items(m);
 447             self.block_indent = self.block_indent.block_unindent(self.config);
 448
 449             self.format_missing_with_indent(m.inner.hi - BytePos(1));
 450             self.buffer.push_str("}");
 451             self.last_pos = m.inner.hi;
 452         }
 453     }
 454
 455     pub fn format_separate_mod(&mut self, m: &ast::Mod, filename: &str) {
 456         let filemap = self.codemap.get_filemap(filename);
 457         self.last_pos = filemap.start_pos;
 458         self.block_indent = Indent::empty();
 459         self.walk_mod_items(m);
 460         self.format_missing(filemap.end_pos);
 461     }
 462
 463     fn format_import(&mut self, vis: ast::Visibility, vp: &ast::ViewPath, span: Span) {
 464         let vis = utils::format_visibility(vis);
 465         let mut offset = self.block_indent;
 466         offset.alignment += vis.len() + "use ".len();
 467         // 1 = ";"
 468         match vp.rewrite(&self.get_context(),
 469                          self.config.max_width - offset.width() - 1,
 470                          offset) {
 471             Some(ref s) if s.is_empty() => {
 472                 // Format up to last newline
 473                 let prev_span = codemap::mk_sp(self.last_pos, span.lo);
 474                 let span_end = match self.snippet(prev_span).rfind('\n') {
 475                     Some(offset) => self.last_pos + BytePos(offset as u32),
 476                     None => span.lo,
 477                 };
 478                 self.format_missing(span_end);
 479                 self.last_pos = span.hi;
 480             }
 481             Some(ref s) => {
 482                 let s = format!("{}use {};", vis, s);
 483                 self.format_missing_with_indent(span.lo);
 484                 self.buffer.push_str(&s);
 485                 self.last_pos = span.hi;
 486             }
 487             None => {
 488                 self.format_missing_with_indent(span.lo);
 489                 self.format_missing(span.hi);
 490             }
 491         }
 492     }
 493
 494     pub fn get_context(&self) -> RewriteContext {
 495         RewriteContext {
 496             parse_session: self.parse_session,
 497             codemap: self.codemap,
 498             config: self.config,
 499             block_indent: self.block_indent,
 500         }
 501     }
 502 }
 503
 504 impl<'a> Rewrite for [ast::Attribute] {
 505     fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
 506         let mut result = String::new();
 507         if self.is_empty() {
 508             return Some(result);
 509         }
 510         let indent = offset.to_string(context.config);
 511
 512         for (i, a) in self.iter().enumerate() {
 513             let a_str = context.snippet(a.span);
 514
 515             if i > 0 {
 516                 let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
 517                 // This particular horror show is to preserve line breaks in between doc
 518                 // comments. An alternative would be to force such line breaks to start
 519                 // with the usual doc comment token.
 520                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 521                 let comment = comment.trim();
 522                 if !comment.is_empty() {
 523                     let comment = try_opt!(rewrite_comment(comment,
 524                                                            false,
 525                                                            context.config.max_width -
 526                                                            offset.width(),
 527                                                            offset,
 528                                                            context.config));
 529                     result.push_str(&indent);
 530                     result.push_str(&comment);
 531                     result.push('\n');
 532                 } else if multi_line {
 533                     result.push('\n');
 534                 }
 535                 result.push_str(&indent);
 536             }
 537
 538             result.push_str(&a_str);
 539
 540             if i < self.len() - 1 {
 541                 result.push('\n');
 542             }
 543         }
 544
 545         Some(result)
 546     }
 547 }