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
 173                         if let Some(new_str) = formatted {
 174                             self.format_missing_with_indent(item.span.lo);
 175                             self.changes.push_str_span(item.span, &new_str);
 176                         } else {
 177                             // Format up to last newline
 178                             let span = codemap::mk_sp(self.last_pos, item.span.lo);
 179                             let span_end = match self.snippet(span).rfind('\n') {
 180                                 Some(offset) => self.last_pos + BytePos(offset as u32),
 181                                 None => item.span.lo
 182                             };
 183                             self.format_missing(span_end);
 184                         }
 185
 186                         self.last_pos = item.span.hi;
 187                     }
 188                     ast::ViewPath_::ViewPathGlob(_) => {
 189                         // FIXME convert to list?
 190                     }
 191                     ast::ViewPath_::ViewPathSimple(_,_) => {}
 192                 }
 193                 visit::walk_item(self, item);
 194             }
 195             ast::Item_::ItemImpl(..) |
 196             ast::Item_::ItemMod(_) |
 197             ast::Item_::ItemTrait(..) => {
 198                 self.block_indent += self.config.tab_spaces;
 199                 visit::walk_item(self, item);
 200                 self.block_indent -= self.config.tab_spaces;
 201             }
 202             ast::Item_::ItemExternCrate(_) => {
 203                 self.format_missing_with_indent(item.span.lo);
 204                 let new_str = self.snippet(item.span);
 205                 self.changes.push_str_span(item.span, &new_str);
 206                 self.last_pos = item.span.hi;
 207             }
 208             ast::Item_::ItemStruct(ref def, ref generics) => {
 209                 self.format_missing_with_indent(item.span.lo);
 210                 self.visit_struct(item.ident,
 211                                   item.vis,
 212                                   def,
 213                                   generics,
 214                                   item.span);
 215                 self.last_pos = item.span.hi;
 216             }
 217             ast::Item_::ItemEnum(ref def, ref generics) => {
 218                 self.format_missing_with_indent(item.span.lo);
 219                 self.visit_enum(item.ident,
 220                                 item.vis,
 221                                 def,
 222                                 generics,
 223                                 item.span);
 224                 self.last_pos = item.span.hi;
 225             }
 226             _ => {
 227                 visit::walk_item(self, item);
 228             }
 229         }
 230     }
 231
 232     fn visit_trait_item(&mut self, ti: &'v ast::TraitItem) {
 233         if self.visit_attrs(&ti.attrs) {
 234             return;
 235         }
 236
 237         if let ast::TraitItem_::MethodTraitItem(ref sig, None) = ti.node {
 238             self.format_missing_with_indent(ti.span.lo);
 239
 240             let indent = self.block_indent;
 241             let new_fn = self.rewrite_required_fn(indent,
 242                                                   ti.ident,
 243                                                   sig,
 244                                                   ti.span);
 245
 246             self.changes.push_str_span(ti.span, &new_fn);
 247             self.last_pos = ti.span.hi;
 248         }
 249         // TODO format trait types
 250
 251         visit::walk_trait_item(self, ti)
 252     }
 253
 254     fn visit_impl_item(&mut self, ii: &'v ast::ImplItem) {
 255         if self.visit_attrs(&ii.attrs) {
 256             return;
 257         }
 258         visit::walk_impl_item(self, ii)
 259     }
 260
 261     fn visit_mac(&mut self, mac: &'v ast::Mac) {
 262         visit::walk_mac(self, mac)
 263     }
 264
 265     fn visit_mod(&mut self, m: &'v ast::Mod, s: Span, _: ast::NodeId) {
 266         // Only visit inline mods here.
 267         if self.codemap.lookup_char_pos(s.lo).file.name !=
 268            self.codemap.lookup_char_pos(m.inner.lo).file.name {
 269             return;
 270         }
 271         visit::walk_mod(self, m);
 272     }
 273 }
 274
 275 impl<'a> FmtVisitor<'a> {
 276     pub fn from_codemap<'b>(codemap: &'b CodeMap, config: &'b Config) -> FmtVisitor<'b> {
 277         FmtVisitor {
 278             codemap: codemap,
 279             changes: ChangeSet::from_codemap(codemap),
 280             last_pos: BytePos(0),
 281             block_indent: 0,
 282             config: config
 283         }
 284     }
 285
 286     pub fn snippet(&self, span: Span) -> String {
 287         match self.codemap.span_to_snippet(span) {
 288             Ok(s) => s,
 289             Err(_) => {
 290                 println!("Couldn't make snippet for span {:?}->{:?}",
 291                          self.codemap.lookup_char_pos(span.lo),
 292                          self.codemap.lookup_char_pos(span.hi));
 293                 "".to_owned()
 294             }
 295         }
 296     }
 297
 298     // Returns true if we should skip the following item.
 299     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 300         if attrs.len() == 0 {
 301             return false;
 302         }
 303
 304         let first = &attrs[0];
 305         self.format_missing_with_indent(first.span.lo);
 306
 307         if utils::contains_skip(attrs) {
 308             true
 309         } else {
 310             let rewrite = self.rewrite_attrs(attrs, self.block_indent);
 311             self.changes.push_str_span(first.span, &rewrite);
 312             let last = attrs.last().unwrap();
 313             self.last_pos = last.span.hi;
 314             false
 315         }
 316     }
 317
 318     pub fn rewrite_attrs(&self, attrs: &[ast::Attribute], indent: usize) -> String {
 319         let mut result = String::new();
 320         let indent = utils::make_indent(indent);
 321
 322         for (i, a) in attrs.iter().enumerate() {
 323             let a_str = self.snippet(a.span);
 324
 325             if i > 0 {
 326                 let comment = self.snippet(codemap::mk_sp(attrs[i-1].span.hi, a.span.lo));
 327                 // This particular horror show is to preserve line breaks in between doc
 328                 // comments. An alternative would be to force such line breaks to start
 329                 // with the usual doc comment token.
 330                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 331                 let comment = comment.trim();
 332                 if comment.len() > 0 {
 333                     result.push_str(&indent);
 334                     result.push_str(comment);
 335                     result.push('\n');
 336                 } else if multi_line {
 337                     result.push('\n');
 338                 }
 339                 result.push_str(&indent);
 340             }
 341
 342             result.push_str(&a_str);
 343
 344             if i < attrs.len() -1 {
 345                 result.push('\n');
 346             }
 347         }
 348
 349         result
 350     }
 351 }