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