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::visit;
  14
  15 use utils;
  16 use config::Config;
  17
  18 use changes::ChangeSet;
  19 use rewrite::{Rewrite, RewriteContext};
  20
  21 pub struct FmtVisitor<'a> {
  22     pub codemap: &'a CodeMap,
  23     pub changes: ChangeSet<'a>,
  24     pub last_pos: BytePos,
  25     // TODO RAII util for indenting
  26     pub block_indent: usize,
  27     pub config: &'a Config,
  28 }
  29
  30 impl<'a, 'v> visit::Visitor<'v> for FmtVisitor<'a> {
  31     fn visit_expr(&mut self, ex: &'v ast::Expr) {
  32         debug!("visit_expr: {:?} {:?}",
  33                self.codemap.lookup_char_pos(ex.span.lo),
  34                self.codemap.lookup_char_pos(ex.span.hi));
  35         self.format_missing(ex.span.lo);
  36         let offset = self.changes.cur_offset_span(ex.span);
  37         let context = RewriteContext { codemap: self.codemap, config: self.config };
  38         let rewrite = ex.rewrite(&context, self.config.max_width - offset, offset);
  39
  40         if let Some(new_str) = rewrite {
  41             self.changes.push_str_span(ex.span, &new_str);
  42             self.last_pos = ex.span.hi;
  43         }
  44     }
  45
  46     fn visit_stmt(&mut self, stmt: &'v ast::Stmt) {
  47         // If the stmt is actually an item, then we'll handle any missing spans
  48         // there. This is important because of annotations.
  49         // Although it might make more sense for the statement span to include
  50         // any annotations on the item.
  51         let skip_missing = match stmt.node {
  52             ast::Stmt_::StmtDecl(ref decl, _) => {
  53                 match decl.node {
  54                     ast::Decl_::DeclItem(_) => true,
  55                     _ => false,
  56                 }
  57             }
  58             _ => false,
  59         };
  60         if !skip_missing {
  61             self.format_missing_with_indent(stmt.span.lo);
  62         }
  63         visit::walk_stmt(self, stmt);
  64     }
  65
  66     fn visit_block(&mut self, b: &'v ast::Block) {
  67         debug!("visit_block: {:?} {:?}",
  68                self.codemap.lookup_char_pos(b.span.lo),
  69                self.codemap.lookup_char_pos(b.span.hi));
  70         self.format_missing(b.span.lo);
  71
  72         self.changes.push_str_span(b.span, "{");
  73         self.last_pos = self.last_pos + BytePos(1);
  74         self.block_indent += self.config.tab_spaces;
  75
  76         for stmt in &b.stmts {
  77             self.visit_stmt(&stmt)
  78         }
  79         match b.expr {
  80             Some(ref e) => {
  81                 self.format_missing_with_indent(e.span.lo);
  82                 self.visit_expr(e);
  83             }
  84             None => {}
  85         }
  86
  87         self.block_indent -= self.config.tab_spaces;
  88         // TODO we should compress any newlines here to just one
  89         self.format_missing_with_indent(b.span.hi - BytePos(1));
  90         self.changes.push_str_span(b.span, "}");
  91         self.last_pos = b.span.hi;
  92     }
  93
  94     // Note that this only gets called for function definitions. Required methods
  95     // on traits do not get handled here.
  96     fn visit_fn(&mut self,
  97                 fk: visit::FnKind<'v>,
  98                 fd: &'v ast::FnDecl,
  99                 b: &'v ast::Block,
 100                 s: Span,
 101                 _: ast::NodeId) {
 102         self.format_missing_with_indent(s.lo);
 103         self.last_pos = s.lo;
 104
 105         let indent = self.block_indent;
 106         match fk {
 107             visit::FkItemFn(ident,
 108                             ref generics,
 109                             ref unsafety,
 110                             ref constness,
 111                             ref abi,
 112                             vis) => {
 113                 let new_fn = self.rewrite_fn(indent,
 114                                              ident,
 115                                              fd,
 116                                              None,
 117                                              generics,
 118                                              unsafety,
 119                                              constness,
 120                                              abi,
 121                                              vis,
 122                                              codemap::mk_sp(s.lo, b.span.lo));
 123                 self.changes.push_str_span(s, &new_fn);
 124             }
 125             visit::FkMethod(ident, ref sig, vis) => {
 126                 let new_fn = self.rewrite_fn(indent,
 127                                              ident,
 128                                              fd,
 129                                              Some(&sig.explicit_self),
 130                                              &sig.generics,
 131                                              &sig.unsafety,
 132                                              &sig.constness,
 133                                              &sig.abi,
 134                                              vis.unwrap_or(ast::Visibility::Inherited),
 135                                              codemap::mk_sp(s.lo, b.span.lo));
 136                 self.changes.push_str_span(s, &new_fn);
 137             }
 138             visit::FkFnBlock(..) => {}
 139         }
 140
 141         self.last_pos = b.span.lo;
 142         self.visit_block(b)
 143     }
 144
 145     fn visit_item(&mut self, item: &'v ast::Item) {
 146         // Don't look at attributes for modules.
 147         // We want to avoid looking at attributes in another file, which the AST
 148         // doesn't distinguish. FIXME This is overly conservative and means we miss
 149         // attributes on inline modules.
 150         match item.node {
 151             ast::Item_::ItemMod(_) => {}
 152             _ => {
 153                 if self.visit_attrs(&item.attrs) {
 154                     return;
 155                 }
 156             }
 157         }
 158
 159         match item.node {
 160             ast::Item_::ItemUse(ref vp) => {
 161                 match vp.node {
 162                     ast::ViewPath_::ViewPathList(ref path, ref path_list) => {
 163                         let block_indent = self.block_indent;
 164                         let one_line_budget = self.config.max_width - block_indent;
 165                         let multi_line_budget = self.config.ideal_width - block_indent;
 166                         let formatted = self.rewrite_use_list(block_indent,
 167                                                               one_line_budget,
 168                                                               multi_line_budget,
 169                                                               path,
 170                                                               path_list,
 171                                                               item.vis,
 172                                                               item.span);
 173
 174                         if let Some(new_str) = formatted {
 175                             self.format_missing_with_indent(item.span.lo);
 176                             self.changes.push_str_span(item.span, &new_str);
 177                         } else {
 178                             // Format up to last newline
 179                             let span = codemap::mk_sp(self.last_pos, item.span.lo);
 180                             let span_end = match self.snippet(span).rfind('\n') {
 181                                 Some(offset) => self.last_pos + BytePos(offset as u32),
 182                                 None => item.span.lo
 183                             };
 184                             self.format_missing(span_end);
 185                         }
 186
 187                         self.last_pos = item.span.hi;
 188                     }
 189                     ast::ViewPath_::ViewPathGlob(_) => {
 190                         self.format_missing_with_indent(item.span.lo);
 191                         // FIXME convert to list?
 192                     }
 193                     ast::ViewPath_::ViewPathSimple(_,_) => {
 194                         self.format_missing_with_indent(item.span.lo);
 195                     }
 196                 }
 197                 visit::walk_item(self, item);
 198             }
 199             ast::Item_::ItemImpl(..) |
 200             ast::Item_::ItemMod(_) |
 201             ast::Item_::ItemTrait(..) => {
 202                 self.block_indent += self.config.tab_spaces;
 203                 visit::walk_item(self, item);
 204                 self.block_indent -= self.config.tab_spaces;
 205             }
 206             ast::Item_::ItemExternCrate(_) => {
 207                 self.format_missing_with_indent(item.span.lo);
 208                 let new_str = self.snippet(item.span);
 209                 self.changes.push_str_span(item.span, &new_str);
 210                 self.last_pos = item.span.hi;
 211             }
 212             ast::Item_::ItemStruct(ref def, ref generics) => {
 213                 self.format_missing_with_indent(item.span.lo);
 214                 self.visit_struct(item.ident,
 215                                   item.vis,
 216                                   def,
 217                                   generics,
 218                                   item.span);
 219                 self.last_pos = item.span.hi;
 220             }
 221             ast::Item_::ItemEnum(ref def, ref generics) => {
 222                 self.format_missing_with_indent(item.span.lo);
 223                 self.visit_enum(item.ident,
 224                                 item.vis,
 225                                 def,
 226                                 generics,
 227                                 item.span);
 228                 self.last_pos = item.span.hi;
 229             }
 230             _ => {
 231                 visit::walk_item(self, item);
 232             }
 233         }
 234     }
 235
 236     fn visit_trait_item(&mut self, ti: &'v ast::TraitItem) {
 237         if self.visit_attrs(&ti.attrs) {
 238             return;
 239         }
 240
 241         if let ast::TraitItem_::MethodTraitItem(ref sig, None) = ti.node {
 242             self.format_missing_with_indent(ti.span.lo);
 243
 244             let indent = self.block_indent;
 245             let new_fn = self.rewrite_required_fn(indent,
 246                                                   ti.ident,
 247                                                   sig,
 248                                                   ti.span);
 249
 250             self.changes.push_str_span(ti.span, &new_fn);
 251             self.last_pos = ti.span.hi;
 252         }
 253         // TODO format trait types
 254
 255         visit::walk_trait_item(self, ti)
 256     }
 257
 258     fn visit_impl_item(&mut self, ii: &'v ast::ImplItem) {
 259         if self.visit_attrs(&ii.attrs) {
 260             return;
 261         }
 262         visit::walk_impl_item(self, ii)
 263     }
 264
 265     fn visit_mac(&mut self, mac: &'v ast::Mac) {
 266         visit::walk_mac(self, mac)
 267     }
 268
 269     fn visit_mod(&mut self, m: &'v ast::Mod, s: Span, _: ast::NodeId) {
 270         // Only visit inline mods here.
 271         if self.codemap.lookup_char_pos(s.lo).file.name !=
 272            self.codemap.lookup_char_pos(m.inner.lo).file.name {
 273             return;
 274         }
 275         visit::walk_mod(self, m);
 276     }
 277 }
 278
 279 impl<'a> FmtVisitor<'a> {
 280     pub fn from_codemap<'b>(codemap: &'b CodeMap, config: &'b Config) -> FmtVisitor<'b> {
 281         FmtVisitor {
 282             codemap: codemap,
 283             changes: ChangeSet::from_codemap(codemap),
 284             last_pos: BytePos(0),
 285             block_indent: 0,
 286             config: config
 287         }
 288     }
 289
 290     pub fn snippet(&self, span: Span) -> String {
 291         match self.codemap.span_to_snippet(span) {
 292             Ok(s) => s,
 293             Err(_) => {
 294                 println!("Couldn't make snippet for span {:?}->{:?}",
 295                          self.codemap.lookup_char_pos(span.lo),
 296                          self.codemap.lookup_char_pos(span.hi));
 297                 "".to_owned()
 298             }
 299         }
 300     }
 301
 302     // Returns true if we should skip the following item.
 303     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 304         if attrs.len() == 0 {
 305             return false;
 306         }
 307
 308         let first = &attrs[0];
 309         self.format_missing_with_indent(first.span.lo);
 310
 311         if utils::contains_skip(attrs) {
 312             true
 313         } else {
 314             let rewrite = self.rewrite_attrs(attrs, self.block_indent);
 315             self.changes.push_str_span(first.span, &rewrite);
 316             let last = attrs.last().unwrap();
 317             self.last_pos = last.span.hi;
 318             false
 319         }
 320     }
 321
 322     pub fn rewrite_attrs(&self, attrs: &[ast::Attribute], indent: usize) -> String {
 323         let mut result = String::new();
 324         let indent = utils::make_indent(indent);
 325
 326         for (i, a) in attrs.iter().enumerate() {
 327             let a_str = self.snippet(a.span);
 328
 329             if i > 0 {
 330                 let comment = self.snippet(codemap::mk_sp(attrs[i-1].span.hi, a.span.lo));
 331                 // This particular horror show is to preserve line breaks in between doc
 332                 // comments. An alternative would be to force such line breaks to start
 333                 // with the usual doc comment token.
 334                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 335                 let comment = comment.trim();
 336                 if comment.len() > 0 {
 337                     result.push_str(&indent);
 338                     result.push_str(comment);
 339                     result.push('\n');
 340                 } else if multi_line {
 341                     result.push('\n');
 342                 }
 343                 result.push_str(&indent);
 344             }
 345
 346             result.push_str(&a_str);
 347
 348             if i < attrs.len() -1 {
 349                 result.push('\n');
 350             }
 351         }
 352
 353         result
 354     }
 355 }