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