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 {IDEAL_WIDTH, MAX_WIDTH, TAB_SPACES, 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, 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 += 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 -= 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, ref generics, ref unsafety, ref abi, vis) => {
 102                 let new_fn = self.rewrite_fn(indent,
 103                                              ident,
 104                                              fd,
 105                                              None,
 106                                              generics,
 107                                              unsafety,
 108                                              abi,
 109                                              vis,
 110                                              b.span);
 111                 self.changes.push_str_span(s, &new_fn);
 112             }
 113             visit::FkMethod(ident, ref sig, vis) => {
 114                 let new_fn = self.rewrite_fn(indent,
 115                                              ident,
 116                                              fd,
 117                                              Some(&sig.explicit_self),
 118                                              &sig.generics,
 119                                              &sig.unsafety,
 120                                              &sig.abi,
 121                                              vis.unwrap_or(ast::Visibility::Inherited),
 122                                              b.span);
 123                 self.changes.push_str_span(s, &new_fn);
 124             }
 125             visit::FkFnBlock(..) => {}
 126         }
 127
 128         self.last_pos = b.span.lo;
 129         self.visit_block(b)
 130     }
 131
 132     fn visit_item(&mut self, item: &'v ast::Item) {
 133         // Don't look at attributes for modules.
 134         // We want to avoid looking at attributes in another file, which the AST
 135         // doesn't distinguish. FIXME This is overly conservative and means we miss
 136         // attributes on inline modules.
 137         match item.node {
 138             ast::Item_::ItemMod(_) => {}
 139             _ => {
 140                 if self.visit_attrs(&item.attrs) {
 141                     return;
 142                 }
 143             }
 144         }
 145
 146         match item.node {
 147             ast::Item_::ItemUse(ref vp) => {
 148                 self.format_missing_with_indent(item.span.lo);
 149                 match vp.node {
 150                     ast::ViewPath_::ViewPathList(ref path, ref path_list) => {
 151                         let block_indent = self.block_indent;
 152                         let one_line_budget = MAX_WIDTH - block_indent;
 153                         let multi_line_budget = IDEAL_WIDTH - block_indent;
 154                         let new_str = self.rewrite_use_list(block_indent,
 155                                                             one_line_budget,
 156                                                             multi_line_budget,
 157                                                             path,
 158                                                             path_list,
 159                                                             item.vis);
 160                         self.changes.push_str_span(item.span, &new_str);
 161                         self.last_pos = item.span.hi;
 162                     }
 163                     ast::ViewPath_::ViewPathGlob(_) => {
 164                         // FIXME convert to list?
 165                     }
 166                     ast::ViewPath_::ViewPathSimple(_,_) => {}
 167                 }
 168                 visit::walk_item(self, item);
 169             }
 170             ast::Item_::ItemImpl(..) |
 171             ast::Item_::ItemMod(_) |
 172             ast::Item_::ItemTrait(..) => {
 173                 self.block_indent += TAB_SPACES;
 174                 visit::walk_item(self, item);
 175                 self.block_indent -= TAB_SPACES;
 176             }
 177             ast::Item_::ItemExternCrate(_) => {
 178                 self.format_missing_with_indent(item.span.lo);
 179                 let new_str = self.snippet(item.span);
 180                 self.changes.push_str_span(item.span, &new_str);
 181                 self.last_pos = item.span.hi;
 182             }
 183             _ => {
 184                 visit::walk_item(self, item);
 185             }
 186         }
 187     }
 188
 189     fn visit_trait_item(&mut self, ti: &'v ast::TraitItem) {
 190         if self.visit_attrs(&ti.attrs) {
 191             return;
 192         }
 193         visit::walk_trait_item(self, ti)
 194     }
 195
 196     fn visit_impl_item(&mut self, ii: &'v ast::ImplItem) {
 197         if self.visit_attrs(&ii.attrs) {
 198             return;
 199         }
 200         visit::walk_impl_item(self, ii)
 201     }
 202
 203     fn visit_mac(&mut self, mac: &'v ast::Mac) {
 204         visit::walk_mac(self, mac)
 205     }
 206
 207     fn visit_mod(&mut self, m: &'v ast::Mod, s: Span, _: ast::NodeId) {
 208         // Only visit inline mods here.
 209         if self.codemap.lookup_char_pos(s.lo).file.name !=
 210            self.codemap.lookup_char_pos(m.inner.lo).file.name {
 211             return;
 212         }
 213         visit::walk_mod(self, m);
 214     }
 215 }
 216
 217 impl<'a> FmtVisitor<'a> {
 218     pub fn from_codemap<'b>(codemap: &'b CodeMap) -> FmtVisitor<'b> {
 219         FmtVisitor {
 220             codemap: codemap,
 221             changes: ChangeSet::from_codemap(codemap),
 222             last_pos: BytePos(0),
 223             block_indent: 0,
 224         }
 225     }
 226
 227     pub fn snippet(&self, span: Span) -> String {
 228         match self.codemap.span_to_snippet(span) {
 229             Ok(s) => s,
 230             Err(_) => {
 231                 println!("Couldn't make snippet for span {:?}->{:?}",
 232                          self.codemap.lookup_char_pos(span.lo),
 233                          self.codemap.lookup_char_pos(span.hi));
 234                 "".to_owned()
 235             }
 236         }
 237     }
 238
 239     // Returns true if we should skip the following item.
 240     fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
 241         if attrs.len() == 0 {
 242             return false;
 243         }
 244
 245         let first = &attrs[0];
 246         self.format_missing_with_indent(first.span.lo);
 247
 248         match self.rewrite_attrs(attrs, self.block_indent) {
 249             Some(s) => {
 250                 self.changes.push_str_span(first.span, &s);
 251                 let last = attrs.last().unwrap();
 252                 self.last_pos = last.span.hi;
 253                 false
 254             }
 255             None => true
 256         }
 257     }
 258
 259     fn rewrite_attrs(&self, attrs: &[ast::Attribute], indent: usize) -> Option<String> {
 260         let mut result = String::new();
 261         let indent = utils::make_indent(indent);
 262
 263         for (i, a) in attrs.iter().enumerate() {
 264             if is_skip(&a.node.value) {
 265                 return None;
 266             }
 267
 268             let a_str = self.snippet(a.span);
 269
 270             if i > 0 {
 271                 let comment = self.snippet(codemap::mk_sp(attrs[i-1].span.hi, a.span.lo));
 272                 // This particular horror show is to preserve line breaks in between doc
 273                 // comments. An alternative would be to force such line breaks to start
 274                 // with the usual doc comment token.
 275                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 276                 let comment = comment.trim();
 277                 if comment.len() > 0 {
 278                     result.push_str(&indent);
 279                     result.push_str(comment);
 280                     result.push('\n');
 281                 } else if multi_line {
 282                     result.push('\n');
 283                 }
 284                 result.push_str(&indent);
 285             }
 286
 287             result.push_str(&a_str);
 288
 289             if i < attrs.len() -1 {
 290                 result.push('\n');
 291             }
 292         }
 293
 294         Some(result)
 295     }
 296 }
 297
 298 fn is_skip(meta_item: &ast::MetaItem) -> bool {
 299     match meta_item.node {
 300         ast::MetaItem_::MetaWord(ref s) => *s == SKIP_ANNOTATION,
 301         _ => false,
 302     }
 303 }