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