src/librustc/hir/print.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 pub use self::AnnNode::*;
  12
  13 use syntax::abi::Abi;
  14 use syntax::ast;
  15 use syntax::codemap::{CodeMap, Spanned};
  16 use syntax::parse::ParseSess;
  17 use syntax::parse::lexer::comments;
  18 use syntax::print::pp::{self, Breaks};
  19 use syntax::print::pp::Breaks::{Consistent, Inconsistent};
  20 use syntax::print::pprust::PrintState;
  21 use syntax::ptr::P;
  22 use syntax::symbol::keywords;
  23 use syntax::util::parser::{self, AssocOp, Fixity};
  24 use syntax_pos::{self, BytePos};
  25
  26 use hir;
  27 use hir::{PatKind, RegionTyParamBound, TraitTyParamBound, TraitBoundModifier, RangeEnd};
  28
  29 use std::cell::Cell;
  30 use std::io::{self, Write, Read};
  31 use std::iter::Peekable;
  32 use std::vec;
  33
  34 pub enum AnnNode<'a> {
  35     NodeName(&'a ast::Name),
  36     NodeBlock(&'a hir::Block),
  37     NodeItem(&'a hir::Item),
  38     NodeSubItem(ast::NodeId),
  39     NodeExpr(&'a hir::Expr),
  40     NodePat(&'a hir::Pat),
  41 }
  42
  43 pub enum Nested {
  44     Item(hir::ItemId),
  45     TraitItem(hir::TraitItemId),
  46     ImplItem(hir::ImplItemId),
  47     Body(hir::BodyId),
  48     BodyArgPat(hir::BodyId, usize)
  49 }
  50
  51 pub trait PpAnn {
  52     fn nested(&self, _state: &mut State, _nested: Nested) -> io::Result<()> {
  53         Ok(())
  54     }
  55     fn pre(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> {
  56         Ok(())
  57     }
  58     fn post(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> {
  59         Ok(())
  60     }
  61 }
  62
  63 pub struct NoAnn;
  64 impl PpAnn for NoAnn {}
  65 pub const NO_ANN: &'static PpAnn = &NoAnn;
  66
  67 impl PpAnn for hir::Crate {
  68     fn nested(&self, state: &mut State, nested: Nested) -> io::Result<()> {
  69         match nested {
  70             Nested::Item(id) => state.print_item(self.item(id.id)),
  71             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  72             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  73             Nested::Body(id) => state.print_expr(&self.body(id).value),
  74             Nested::BodyArgPat(id, i) => state.print_pat(&self.body(id).arguments[i].pat)
  75         }
  76     }
  77 }
  78
  79 pub struct State<'a> {
  80     pub s: pp::Printer<'a>,
  81     cm: Option<&'a CodeMap>,
  82     comments: Option<Vec<comments::Comment>>,
  83     literals: Peekable<vec::IntoIter<comments::Literal>>,
  84     cur_cmnt: usize,
  85     boxes: Vec<pp::Breaks>,
  86     ann: &'a (PpAnn + 'a),
  87 }
  88
  89 impl<'a> PrintState<'a> for State<'a> {
  90     fn writer(&mut self) -> &mut pp::Printer<'a> {
  91         &mut self.s
  92     }
  93
  94     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
  95         &mut self.boxes
  96     }
  97
  98     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
  99         &mut self.comments
 100     }
 101
 102     fn cur_cmnt(&mut self) -> &mut usize {
 103         &mut self.cur_cmnt
 104     }
 105
 106     fn cur_lit(&mut self) -> Option<&comments::Literal> {
 107         self.literals.peek()
 108     }
 109
 110     fn bump_lit(&mut self) -> Option<comments::Literal> {
 111         self.literals.next()
 112     }
 113 }
 114
 115 #[allow(non_upper_case_globals)]
 116 pub const indent_unit: usize = 4;
 117
 118 #[allow(non_upper_case_globals)]
 119 pub const default_columns: usize = 78;
 120
 121
 122 /// Requires you to pass an input filename and reader so that
 123 /// it can scan the input text for comments and literals to
 124 /// copy forward.
 125 pub fn print_crate<'a>(cm: &'a CodeMap,
 126                        sess: &ParseSess,
 127                        krate: &hir::Crate,
 128                        filename: String,
 129                        input: &mut Read,
 130                        out: Box<Write + 'a>,
 131                        ann: &'a PpAnn,
 132                        is_expanded: bool)
 133                        -> io::Result<()> {
 134     let mut s = State::new_from_input(cm, sess, filename, input, out, ann, is_expanded);
 135
 136     // When printing the AST, we sometimes need to inject `#[no_std]` here.
 137     // Since you can't compile the HIR, it's not necessary.
 138
 139     s.print_mod(&krate.module, &krate.attrs)?;
 140     s.print_remaining_comments()?;
 141     s.s.eof()
 142 }
 143
 144 impl<'a> State<'a> {
 145     pub fn new_from_input(cm: &'a CodeMap,
 146                           sess: &ParseSess,
 147                           filename: String,
 148                           input: &mut Read,
 149                           out: Box<Write + 'a>,
 150                           ann: &'a PpAnn,
 151                           is_expanded: bool)
 152                           -> State<'a> {
 153         let (cmnts, lits) = comments::gather_comments_and_literals(sess, filename, input);
 154
 155         State::new(cm,
 156                    out,
 157                    ann,
 158                    Some(cmnts),
 159                    // If the code is post expansion, don't use the table of
 160                    // literals, since it doesn't correspond with the literals
 161                    // in the AST anymore.
 162                    if is_expanded {
 163                        None
 164                    } else {
 165                        Some(lits)
 166                    })
 167     }
 168
 169     pub fn new(cm: &'a CodeMap,
 170                out: Box<Write + 'a>,
 171                ann: &'a PpAnn,
 172                comments: Option<Vec<comments::Comment>>,
 173                literals: Option<Vec<comments::Literal>>)
 174                -> State<'a> {
 175         State {
 176             s: pp::mk_printer(out, default_columns),
 177             cm: Some(cm),
 178             comments: comments.clone(),
 179             literals: literals.unwrap_or_default().into_iter().peekable(),
 180             cur_cmnt: 0,
 181             boxes: Vec::new(),
 182             ann,
 183         }
 184     }
 185 }
 186
 187 pub fn to_string<F>(ann: &PpAnn, f: F) -> String
 188     where F: FnOnce(&mut State) -> io::Result<()>
 189 {
 190     let mut wr = Vec::new();
 191     {
 192         let mut printer = State {
 193             s: pp::mk_printer(Box::new(&mut wr), default_columns),
 194             cm: None,
 195             comments: None,
 196             literals: vec![].into_iter().peekable(),
 197             cur_cmnt: 0,
 198             boxes: Vec::new(),
 199             ann,
 200         };
 201         f(&mut printer).unwrap();
 202         printer.s.eof().unwrap();
 203     }
 204     String::from_utf8(wr).unwrap()
 205 }
 206
 207 pub fn visibility_qualified(vis: &hir::Visibility, w: &str) -> String {
 208     to_string(NO_ANN, |s| {
 209         s.print_visibility(vis)?;
 210         s.s.word(w)
 211     })
 212 }
 213
 214 impl<'a> State<'a> {
 215     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 216         self.boxes.push(pp::Breaks::Consistent);
 217         self.s.cbox(u)
 218     }
 219
 220     pub fn nbsp(&mut self) -> io::Result<()> {
 221         self.s.word(" ")
 222     }
 223
 224     pub fn word_nbsp(&mut self, w: &str) -> io::Result<()> {
 225         self.s.word(w)?;
 226         self.nbsp()
 227     }
 228
 229     pub fn head(&mut self, w: &str) -> io::Result<()> {
 230         // outer-box is consistent
 231         self.cbox(indent_unit)?;
 232         // head-box is inconsistent
 233         self.ibox(w.len() + 1)?;
 234         // keyword that starts the head
 235         if !w.is_empty() {
 236             self.word_nbsp(w)?;
 237         }
 238         Ok(())
 239     }
 240
 241     pub fn bopen(&mut self) -> io::Result<()> {
 242         self.s.word("{")?;
 243         self.end() // close the head-box
 244     }
 245
 246     pub fn bclose_(&mut self, span: syntax_pos::Span, indented: usize) -> io::Result<()> {
 247         self.bclose_maybe_open(span, indented, true)
 248     }
 249     pub fn bclose_maybe_open(&mut self,
 250                              span: syntax_pos::Span,
 251                              indented: usize,
 252                              close_box: bool)
 253                              -> io::Result<()> {
 254         self.maybe_print_comment(span.hi())?;
 255         self.break_offset_if_not_bol(1, -(indented as isize))?;
 256         self.s.word("}")?;
 257         if close_box {
 258             self.end()?; // close the outer-box
 259         }
 260         Ok(())
 261     }
 262     pub fn bclose(&mut self, span: syntax_pos::Span) -> io::Result<()> {
 263         self.bclose_(span, indent_unit)
 264     }
 265
 266     pub fn in_cbox(&self) -> bool {
 267         match self.boxes.last() {
 268             Some(&last_box) => last_box == pp::Breaks::Consistent,
 269             None => false,
 270         }
 271     }
 272     pub fn space_if_not_bol(&mut self) -> io::Result<()> {
 273         if !self.is_bol() {
 274             self.s.space()?;
 275         }
 276         Ok(())
 277     }
 278     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) -> io::Result<()> {
 279         if !self.is_bol() {
 280             self.s.break_offset(n, off)
 281         } else {
 282             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 283                 // We do something pretty sketchy here: tuck the nonzero
 284                 // offset-adjustment we were going to deposit along with the
 285                 // break into the previous hardbreak.
 286                 self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 287             }
 288             Ok(())
 289         }
 290     }
 291
 292     // Synthesizes a comment that was not textually present in the original source
 293     // file.
 294     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 295         self.s.word("/*")?;
 296         self.s.space()?;
 297         self.s.word(&text[..])?;
 298         self.s.space()?;
 299         self.s.word("*/")
 300     }
 301
 302
 303     pub fn commasep_cmnt<T, F, G>(&mut self,
 304                                   b: Breaks,
 305                                   elts: &[T],
 306                                   mut op: F,
 307                                   mut get_span: G)
 308                                   -> io::Result<()>
 309         where F: FnMut(&mut State, &T) -> io::Result<()>,
 310               G: FnMut(&T) -> syntax_pos::Span
 311     {
 312         self.rbox(0, b)?;
 313         let len = elts.len();
 314         let mut i = 0;
 315         for elt in elts {
 316             self.maybe_print_comment(get_span(elt).hi())?;
 317             op(self, elt)?;
 318             i += 1;
 319             if i < len {
 320                 self.s.word(",")?;
 321                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()))?;
 322                 self.space_if_not_bol()?;
 323             }
 324         }
 325         self.end()
 326     }
 327
 328     pub fn commasep_exprs(&mut self, b: Breaks, exprs: &[hir::Expr]) -> io::Result<()> {
 329         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 330     }
 331
 332     pub fn print_mod(&mut self, _mod: &hir::Mod, attrs: &[ast::Attribute]) -> io::Result<()> {
 333         self.print_inner_attributes(attrs)?;
 334         for &item_id in &_mod.item_ids {
 335             self.ann.nested(self, Nested::Item(item_id))?;
 336         }
 337         Ok(())
 338     }
 339
 340     pub fn print_foreign_mod(&mut self,
 341                              nmod: &hir::ForeignMod,
 342                              attrs: &[ast::Attribute])
 343                              -> io::Result<()> {
 344         self.print_inner_attributes(attrs)?;
 345         for item in &nmod.items {
 346             self.print_foreign_item(item)?;
 347         }
 348         Ok(())
 349     }
 350
 351     pub fn print_opt_lifetime(&mut self, lifetime: &hir::Lifetime) -> io::Result<()> {
 352         if !lifetime.is_elided() {
 353             self.print_lifetime(lifetime)?;
 354             self.nbsp()?;
 355         }
 356         Ok(())
 357     }
 358
 359     pub fn print_type(&mut self, ty: &hir::Ty) -> io::Result<()> {
 360         self.maybe_print_comment(ty.span.lo())?;
 361         self.ibox(0)?;
 362         match ty.node {
 363             hir::TySlice(ref ty) => {
 364                 self.s.word("[")?;
 365                 self.print_type(&ty)?;
 366                 self.s.word("]")?;
 367             }
 368             hir::TyPtr(ref mt) => {
 369                 self.s.word("*")?;
 370                 match mt.mutbl {
 371                     hir::MutMutable => self.word_nbsp("mut")?,
 372                     hir::MutImmutable => self.word_nbsp("const")?,
 373                 }
 374                 self.print_type(&mt.ty)?;
 375             }
 376             hir::TyRptr(ref lifetime, ref mt) => {
 377                 self.s.word("&")?;
 378                 self.print_opt_lifetime(lifetime)?;
 379                 self.print_mt(mt)?;
 380             }
 381             hir::TyNever => {
 382                 self.s.word("!")?;
 383             },
 384             hir::TyTup(ref elts) => {
 385                 self.popen()?;
 386                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(&ty))?;
 387                 if elts.len() == 1 {
 388                     self.s.word(",")?;
 389                 }
 390                 self.pclose()?;
 391             }
 392             hir::TyBareFn(ref f) => {
 393                 let generics = hir::Generics {
 394                     lifetimes: f.lifetimes.clone(),
 395                     ty_params: hir::HirVec::new(),
 396                     where_clause: hir::WhereClause {
 397                         id: ast::DUMMY_NODE_ID,
 398                         predicates: hir::HirVec::new(),
 399                     },
 400                     span: syntax_pos::DUMMY_SP,
 401                 };
 402                 self.print_ty_fn(f.abi, f.unsafety, &f.decl, None, &generics,
 403                                  &f.arg_names[..])?;
 404             }
 405             hir::TyPath(ref qpath) => {
 406                 self.print_qpath(qpath, false)?
 407             }
 408             hir::TyTraitObject(ref bounds, ref lifetime) => {
 409                 let mut first = true;
 410                 for bound in bounds {
 411                     self.nbsp()?;
 412                     if first {
 413                         first = false;
 414                     } else {
 415                         self.word_space("+")?;
 416                     }
 417                     self.print_poly_trait_ref(bound)?;
 418                 }
 419                 if !lifetime.is_elided() {
 420                     self.word_space("+")?;
 421                     self.print_lifetime(lifetime)?;
 422                 }
 423             }
 424             hir::TyImplTrait(ref bounds) => {
 425                 self.print_bounds("impl ", &bounds[..])?;
 426             }
 427             hir::TyArray(ref ty, v) => {
 428                 self.s.word("[")?;
 429                 self.print_type(&ty)?;
 430                 self.s.word("; ")?;
 431                 self.ann.nested(self, Nested::Body(v))?;
 432                 self.s.word("]")?;
 433             }
 434             hir::TyTypeof(e) => {
 435                 self.s.word("typeof(")?;
 436                 self.ann.nested(self, Nested::Body(e))?;
 437                 self.s.word(")")?;
 438             }
 439             hir::TyInfer => {
 440                 self.s.word("_")?;
 441             }
 442             hir::TyErr => {
 443                 self.s.word("?")?;
 444             }
 445         }
 446         self.end()
 447     }
 448
 449     pub fn print_foreign_item(&mut self, item: &hir::ForeignItem) -> io::Result<()> {
 450         self.hardbreak_if_not_bol()?;
 451         self.maybe_print_comment(item.span.lo())?;
 452         self.print_outer_attributes(&item.attrs)?;
 453         match item.node {
 454             hir::ForeignItemFn(ref decl, ref arg_names, ref generics) => {
 455                 self.head("")?;
 456                 self.print_fn(decl,
 457                               hir::Unsafety::Normal,
 458                               hir::Constness::NotConst,
 459                               Abi::Rust,
 460                               Some(item.name),
 461                               generics,
 462                               &item.vis,
 463                               arg_names,
 464                               None)?;
 465                 self.end()?; // end head-ibox
 466                 self.s.word(";")?;
 467                 self.end() // end the outer fn box
 468             }
 469             hir::ForeignItemStatic(ref t, m) => {
 470                 self.head(&visibility_qualified(&item.vis, "static"))?;
 471                 if m {
 472                     self.word_space("mut")?;
 473                 }
 474                 self.print_name(item.name)?;
 475                 self.word_space(":")?;
 476                 self.print_type(&t)?;
 477                 self.s.word(";")?;
 478                 self.end()?; // end the head-ibox
 479                 self.end() // end the outer cbox
 480             }
 481             hir::ForeignItemType => {
 482                 self.head(&visibility_qualified(&item.vis, "type"))?;
 483                 self.print_name(item.name)?;
 484                 self.s.word(";")?;
 485                 self.end()?; // end the head-ibox
 486                 self.end() // end the outer cbox
 487             }
 488         }
 489     }
 490
 491     fn print_associated_const(&mut self,
 492                               name: ast::Name,
 493                               ty: &hir::Ty,
 494                               default: Option<hir::BodyId>,
 495                               vis: &hir::Visibility)
 496                               -> io::Result<()> {
 497         self.s.word(&visibility_qualified(vis, ""))?;
 498         self.word_space("const")?;
 499         self.print_name(name)?;
 500         self.word_space(":")?;
 501         self.print_type(ty)?;
 502         if let Some(expr) = default {
 503             self.s.space()?;
 504             self.word_space("=")?;
 505             self.ann.nested(self, Nested::Body(expr))?;
 506         }
 507         self.s.word(";")
 508     }
 509
 510     fn print_associated_type(&mut self,
 511                              name: ast::Name,
 512                              bounds: Option<&hir::TyParamBounds>,
 513                              ty: Option<&hir::Ty>)
 514                              -> io::Result<()> {
 515         self.word_space("type")?;
 516         self.print_name(name)?;
 517         if let Some(bounds) = bounds {
 518             self.print_bounds(":", bounds)?;
 519         }
 520         if let Some(ty) = ty {
 521             self.s.space()?;
 522             self.word_space("=")?;
 523             self.print_type(ty)?;
 524         }
 525         self.s.word(";")
 526     }
 527
 528     /// Pretty-print an item
 529     pub fn print_item(&mut self, item: &hir::Item) -> io::Result<()> {
 530         self.hardbreak_if_not_bol()?;
 531         self.maybe_print_comment(item.span.lo())?;
 532         self.print_outer_attributes(&item.attrs)?;
 533         self.ann.pre(self, NodeItem(item))?;
 534         match item.node {
 535             hir::ItemExternCrate(ref optional_path) => {
 536                 self.head(&visibility_qualified(&item.vis, "extern crate"))?;
 537                 if let Some(p) = *optional_path {
 538                     let val = p.as_str();
 539                     if val.contains("-") {
 540                         self.print_string(&val, ast::StrStyle::Cooked)?;
 541                     } else {
 542                         self.print_name(p)?;
 543                     }
 544                     self.s.space()?;
 545                     self.s.word("as")?;
 546                     self.s.space()?;
 547                 }
 548                 self.print_name(item.name)?;
 549                 self.s.word(";")?;
 550                 self.end()?; // end inner head-block
 551                 self.end()?; // end outer head-block
 552             }
 553             hir::ItemUse(ref path, kind) => {
 554                 self.head(&visibility_qualified(&item.vis, "use"))?;
 555                 self.print_path(path, false)?;
 556
 557                 match kind {
 558                     hir::UseKind::Single => {
 559                         if path.segments.last().unwrap().name != item.name {
 560                             self.s.space()?;
 561                             self.word_space("as")?;
 562                             self.print_name(item.name)?;
 563                         }
 564                         self.s.word(";")?;
 565                     }
 566                     hir::UseKind::Glob => self.s.word("::*;")?,
 567                     hir::UseKind::ListStem => self.s.word("::{};")?
 568                 }
 569                 self.end()?; // end inner head-block
 570                 self.end()?; // end outer head-block
 571             }
 572             hir::ItemStatic(ref ty, m, expr) => {
 573                 self.head(&visibility_qualified(&item.vis, "static"))?;
 574                 if m == hir::MutMutable {
 575                     self.word_space("mut")?;
 576                 }
 577                 self.print_name(item.name)?;
 578                 self.word_space(":")?;
 579                 self.print_type(&ty)?;
 580                 self.s.space()?;
 581                 self.end()?; // end the head-ibox
 582
 583                 self.word_space("=")?;
 584                 self.ann.nested(self, Nested::Body(expr))?;
 585                 self.s.word(";")?;
 586                 self.end()?; // end the outer cbox
 587             }
 588             hir::ItemConst(ref ty, expr) => {
 589                 self.head(&visibility_qualified(&item.vis, "const"))?;
 590                 self.print_name(item.name)?;
 591                 self.word_space(":")?;
 592                 self.print_type(&ty)?;
 593                 self.s.space()?;
 594                 self.end()?; // end the head-ibox
 595
 596                 self.word_space("=")?;
 597                 self.ann.nested(self, Nested::Body(expr))?;
 598                 self.s.word(";")?;
 599                 self.end()?; // end the outer cbox
 600             }
 601             hir::ItemFn(ref decl, unsafety, constness, abi, ref typarams, body) => {
 602                 self.head("")?;
 603                 self.print_fn(decl,
 604                               unsafety,
 605                               constness,
 606                               abi,
 607                               Some(item.name),
 608                               typarams,
 609                               &item.vis,
 610                               &[],
 611                               Some(body))?;
 612                 self.s.word(" ")?;
 613                 self.end()?; // need to close a box
 614                 self.end()?; // need to close a box
 615                 self.ann.nested(self, Nested::Body(body))?;
 616             }
 617             hir::ItemMod(ref _mod) => {
 618                 self.head(&visibility_qualified(&item.vis, "mod"))?;
 619                 self.print_name(item.name)?;
 620                 self.nbsp()?;
 621                 self.bopen()?;
 622                 self.print_mod(_mod, &item.attrs)?;
 623                 self.bclose(item.span)?;
 624             }
 625             hir::ItemForeignMod(ref nmod) => {
 626                 self.head("extern")?;
 627                 self.word_nbsp(&nmod.abi.to_string())?;
 628                 self.bopen()?;
 629                 self.print_foreign_mod(nmod, &item.attrs)?;
 630                 self.bclose(item.span)?;
 631             }
 632             hir::ItemGlobalAsm(ref ga) => {
 633                 self.head(&visibility_qualified(&item.vis, "global asm"))?;
 634                 self.s.word(&ga.asm.as_str())?;
 635                 self.end()?
 636             }
 637             hir::ItemTy(ref ty, ref params) => {
 638                 self.ibox(indent_unit)?;
 639                 self.ibox(0)?;
 640                 self.word_nbsp(&visibility_qualified(&item.vis, "type"))?;
 641                 self.print_name(item.name)?;
 642                 self.print_generics(params)?;
 643                 self.end()?; // end the inner ibox
 644
 645                 self.print_where_clause(&params.where_clause)?;
 646                 self.s.space()?;
 647                 self.word_space("=")?;
 648                 self.print_type(&ty)?;
 649                 self.s.word(";")?;
 650                 self.end()?; // end the outer ibox
 651             }
 652             hir::ItemEnum(ref enum_definition, ref params) => {
 653                 self.print_enum_def(enum_definition, params, item.name, item.span, &item.vis)?;
 654             }
 655             hir::ItemStruct(ref struct_def, ref generics) => {
 656                 self.head(&visibility_qualified(&item.vis, "struct"))?;
 657                 self.print_struct(struct_def, generics, item.name, item.span, true)?;
 658             }
 659             hir::ItemUnion(ref struct_def, ref generics) => {
 660                 self.head(&visibility_qualified(&item.vis, "union"))?;
 661                 self.print_struct(struct_def, generics, item.name, item.span, true)?;
 662             }
 663             hir::ItemDefaultImpl(unsafety, ref trait_ref) => {
 664                 self.head("")?;
 665                 self.print_visibility(&item.vis)?;
 666                 self.print_unsafety(unsafety)?;
 667                 self.word_nbsp("impl")?;
 668                 self.print_trait_ref(trait_ref)?;
 669                 self.s.space()?;
 670                 self.word_space("for")?;
 671                 self.word_space("..")?;
 672                 self.bopen()?;
 673                 self.bclose(item.span)?;
 674             }
 675             hir::ItemImpl(unsafety,
 676                           polarity,
 677                           defaultness,
 678                           ref generics,
 679                           ref opt_trait,
 680                           ref ty,
 681                           ref impl_items) => {
 682                 self.head("")?;
 683                 self.print_visibility(&item.vis)?;
 684                 self.print_defaultness(defaultness)?;
 685                 self.print_unsafety(unsafety)?;
 686                 self.word_nbsp("impl")?;
 687
 688                 if generics.is_parameterized() {
 689                     self.print_generics(generics)?;
 690                     self.s.space()?;
 691                 }
 692
 693                 match polarity {
 694                     hir::ImplPolarity::Negative => {
 695                         self.s.word("!")?;
 696                     }
 697                     _ => {}
 698                 }
 699
 700                 match opt_trait {
 701                     &Some(ref t) => {
 702                         self.print_trait_ref(t)?;
 703                         self.s.space()?;
 704                         self.word_space("for")?;
 705                     }
 706                     &None => {}
 707                 }
 708
 709                 self.print_type(&ty)?;
 710                 self.print_where_clause(&generics.where_clause)?;
 711
 712                 self.s.space()?;
 713                 self.bopen()?;
 714                 self.print_inner_attributes(&item.attrs)?;
 715                 for impl_item in impl_items {
 716                     self.ann.nested(self, Nested::ImplItem(impl_item.id))?;
 717                 }
 718                 self.bclose(item.span)?;
 719             }
 720             hir::ItemTrait(unsafety, ref generics, ref bounds, ref trait_items) => {
 721                 self.head("")?;
 722                 self.print_visibility(&item.vis)?;
 723                 self.print_unsafety(unsafety)?;
 724                 self.word_nbsp("trait")?;
 725                 self.print_name(item.name)?;
 726                 self.print_generics(generics)?;
 727                 let mut real_bounds = Vec::with_capacity(bounds.len());
 728                 for b in bounds.iter() {
 729                     if let TraitTyParamBound(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 730                         self.s.space()?;
 731                         self.word_space("for ?")?;
 732                         self.print_trait_ref(&ptr.trait_ref)?;
 733                     } else {
 734                         real_bounds.push(b.clone());
 735                     }
 736                 }
 737                 self.print_bounds(":", &real_bounds[..])?;
 738                 self.print_where_clause(&generics.where_clause)?;
 739                 self.s.word(" ")?;
 740                 self.bopen()?;
 741                 for trait_item in trait_items {
 742                     self.ann.nested(self, Nested::TraitItem(trait_item.id))?;
 743                 }
 744                 self.bclose(item.span)?;
 745             }
 746         }
 747         self.ann.post(self, NodeItem(item))
 748     }
 749
 750     pub fn print_trait_ref(&mut self, t: &hir::TraitRef) -> io::Result<()> {
 751         self.print_path(&t.path, false)
 752     }
 753
 754     fn print_formal_lifetime_list(&mut self, lifetimes: &[hir::LifetimeDef]) -> io::Result<()> {
 755         if !lifetimes.is_empty() {
 756             self.s.word("for<")?;
 757             let mut comma = false;
 758             for lifetime_def in lifetimes {
 759                 if comma {
 760                     self.word_space(",")?
 761                 }
 762                 self.print_lifetime_def(lifetime_def)?;
 763                 comma = true;
 764             }
 765             self.s.word(">")?;
 766         }
 767         Ok(())
 768     }
 769
 770     fn print_poly_trait_ref(&mut self, t: &hir::PolyTraitRef) -> io::Result<()> {
 771         self.print_formal_lifetime_list(&t.bound_lifetimes)?;
 772         self.print_trait_ref(&t.trait_ref)
 773     }
 774
 775     pub fn print_enum_def(&mut self,
 776                           enum_definition: &hir::EnumDef,
 777                           generics: &hir::Generics,
 778                           name: ast::Name,
 779                           span: syntax_pos::Span,
 780                           visibility: &hir::Visibility)
 781                           -> io::Result<()> {
 782         self.head(&visibility_qualified(visibility, "enum"))?;
 783         self.print_name(name)?;
 784         self.print_generics(generics)?;
 785         self.print_where_clause(&generics.where_clause)?;
 786         self.s.space()?;
 787         self.print_variants(&enum_definition.variants, span)
 788     }
 789
 790     pub fn print_variants(&mut self,
 791                           variants: &[hir::Variant],
 792                           span: syntax_pos::Span)
 793                           -> io::Result<()> {
 794         self.bopen()?;
 795         for v in variants {
 796             self.space_if_not_bol()?;
 797             self.maybe_print_comment(v.span.lo())?;
 798             self.print_outer_attributes(&v.node.attrs)?;
 799             self.ibox(indent_unit)?;
 800             self.print_variant(v)?;
 801             self.s.word(",")?;
 802             self.end()?;
 803             self.maybe_print_trailing_comment(v.span, None)?;
 804         }
 805         self.bclose(span)
 806     }
 807
 808     pub fn print_visibility(&mut self, vis: &hir::Visibility) -> io::Result<()> {
 809         match *vis {
 810             hir::Public => self.word_nbsp("pub"),
 811             hir::Visibility::Crate => self.word_nbsp("pub(crate)"),
 812             hir::Visibility::Restricted { ref path, .. } => {
 813                 self.s.word("pub(")?;
 814                 self.print_path(path, false)?;
 815                 self.word_nbsp(")")
 816             }
 817             hir::Inherited => Ok(()),
 818         }
 819     }
 820
 821     pub fn print_defaultness(&mut self, defaultness: hir::Defaultness) -> io::Result<()> {
 822         match defaultness {
 823             hir::Defaultness::Default { .. } => self.word_nbsp("default")?,
 824             hir::Defaultness::Final => (),
 825         }
 826         Ok(())
 827     }
 828
 829     pub fn print_struct(&mut self,
 830                         struct_def: &hir::VariantData,
 831                         generics: &hir::Generics,
 832                         name: ast::Name,
 833                         span: syntax_pos::Span,
 834                         print_finalizer: bool)
 835                         -> io::Result<()> {
 836         self.print_name(name)?;
 837         self.print_generics(generics)?;
 838         if !struct_def.is_struct() {
 839             if struct_def.is_tuple() {
 840                 self.popen()?;
 841                 self.commasep(Inconsistent, struct_def.fields(), |s, field| {
 842                     s.maybe_print_comment(field.span.lo())?;
 843                     s.print_outer_attributes(&field.attrs)?;
 844                     s.print_visibility(&field.vis)?;
 845                     s.print_type(&field.ty)
 846                 })?;
 847                 self.pclose()?;
 848             }
 849             self.print_where_clause(&generics.where_clause)?;
 850             if print_finalizer {
 851                 self.s.word(";")?;
 852             }
 853             self.end()?;
 854             self.end() // close the outer-box
 855         } else {
 856             self.print_where_clause(&generics.where_clause)?;
 857             self.nbsp()?;
 858             self.bopen()?;
 859             self.hardbreak_if_not_bol()?;
 860
 861             for field in struct_def.fields() {
 862                 self.hardbreak_if_not_bol()?;
 863                 self.maybe_print_comment(field.span.lo())?;
 864                 self.print_outer_attributes(&field.attrs)?;
 865                 self.print_visibility(&field.vis)?;
 866                 self.print_name(field.name)?;
 867                 self.word_nbsp(":")?;
 868                 self.print_type(&field.ty)?;
 869                 self.s.word(",")?;
 870             }
 871
 872             self.bclose(span)
 873         }
 874     }
 875
 876     pub fn print_variant(&mut self, v: &hir::Variant) -> io::Result<()> {
 877         self.head("")?;
 878         let generics = hir::Generics::empty();
 879         self.print_struct(&v.node.data, &generics, v.node.name, v.span, false)?;
 880         if let Some(d) = v.node.disr_expr {
 881             self.s.space()?;
 882             self.word_space("=")?;
 883             self.ann.nested(self, Nested::Body(d))?;
 884         }
 885         Ok(())
 886     }
 887     pub fn print_method_sig(&mut self,
 888                             name: ast::Name,
 889                             m: &hir::MethodSig,
 890                             generics: &hir::Generics,
 891                             vis: &hir::Visibility,
 892                             arg_names: &[Spanned<ast::Name>],
 893                             body_id: Option<hir::BodyId>)
 894                             -> io::Result<()> {
 895         self.print_fn(&m.decl,
 896                       m.unsafety,
 897                       m.constness,
 898                       m.abi,
 899                       Some(name),
 900                       generics,
 901                       vis,
 902                       arg_names,
 903                       body_id)
 904     }
 905
 906     pub fn print_trait_item(&mut self, ti: &hir::TraitItem) -> io::Result<()> {
 907         self.ann.pre(self, NodeSubItem(ti.id))?;
 908         self.hardbreak_if_not_bol()?;
 909         self.maybe_print_comment(ti.span.lo())?;
 910         self.print_outer_attributes(&ti.attrs)?;
 911         match ti.node {
 912             hir::TraitItemKind::Const(ref ty, default) => {
 913                 self.print_associated_const(ti.name, &ty, default, &hir::Inherited)?;
 914             }
 915             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(ref arg_names)) => {
 916                 self.print_method_sig(ti.name, sig, &ti.generics, &hir::Inherited, arg_names,
 917                     None)?;
 918                 self.s.word(";")?;
 919             }
 920             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Provided(body)) => {
 921                 self.head("")?;
 922                 self.print_method_sig(ti.name, sig, &ti.generics, &hir::Inherited, &[],
 923                     Some(body))?;
 924                 self.nbsp()?;
 925                 self.end()?; // need to close a box
 926                 self.end()?; // need to close a box
 927                 self.ann.nested(self, Nested::Body(body))?;
 928             }
 929             hir::TraitItemKind::Type(ref bounds, ref default) => {
 930                 self.print_associated_type(ti.name,
 931                                            Some(bounds),
 932                                            default.as_ref().map(|ty| &**ty))?;
 933             }
 934         }
 935         self.ann.post(self, NodeSubItem(ti.id))
 936     }
 937
 938     pub fn print_impl_item(&mut self, ii: &hir::ImplItem) -> io::Result<()> {
 939         self.ann.pre(self, NodeSubItem(ii.id))?;
 940         self.hardbreak_if_not_bol()?;
 941         self.maybe_print_comment(ii.span.lo())?;
 942         self.print_outer_attributes(&ii.attrs)?;
 943         self.print_defaultness(ii.defaultness)?;
 944
 945         match ii.node {
 946             hir::ImplItemKind::Const(ref ty, expr) => {
 947                 self.print_associated_const(ii.name, &ty, Some(expr), &ii.vis)?;
 948             }
 949             hir::ImplItemKind::Method(ref sig, body) => {
 950                 self.head("")?;
 951                 self.print_method_sig(ii.name, sig, &ii.generics, &ii.vis, &[], Some(body))?;
 952                 self.nbsp()?;
 953                 self.end()?; // need to close a box
 954                 self.end()?; // need to close a box
 955                 self.ann.nested(self, Nested::Body(body))?;
 956             }
 957             hir::ImplItemKind::Type(ref ty) => {
 958                 self.print_associated_type(ii.name, None, Some(ty))?;
 959             }
 960         }
 961         self.ann.post(self, NodeSubItem(ii.id))
 962     }
 963
 964     pub fn print_stmt(&mut self, st: &hir::Stmt) -> io::Result<()> {
 965         self.maybe_print_comment(st.span.lo())?;
 966         match st.node {
 967             hir::StmtDecl(ref decl, _) => {
 968                 self.print_decl(&decl)?;
 969             }
 970             hir::StmtExpr(ref expr, _) => {
 971                 self.space_if_not_bol()?;
 972                 self.print_expr(&expr)?;
 973             }
 974             hir::StmtSemi(ref expr, _) => {
 975                 self.space_if_not_bol()?;
 976                 self.print_expr(&expr)?;
 977                 self.s.word(";")?;
 978             }
 979         }
 980         if stmt_ends_with_semi(&st.node) {
 981             self.s.word(";")?;
 982         }
 983         self.maybe_print_trailing_comment(st.span, None)
 984     }
 985
 986     pub fn print_block(&mut self, blk: &hir::Block) -> io::Result<()> {
 987         self.print_block_with_attrs(blk, &[])
 988     }
 989
 990     pub fn print_block_unclosed(&mut self, blk: &hir::Block) -> io::Result<()> {
 991         self.print_block_unclosed_indent(blk, indent_unit)
 992     }
 993
 994     pub fn print_block_unclosed_indent(&mut self,
 995                                        blk: &hir::Block,
 996                                        indented: usize)
 997                                        -> io::Result<()> {
 998         self.print_block_maybe_unclosed(blk, indented, &[], false)
 999     }
1000
1001     pub fn print_block_with_attrs(&mut self,
1002                                   blk: &hir::Block,
1003                                   attrs: &[ast::Attribute])
1004                                   -> io::Result<()> {
1005         self.print_block_maybe_unclosed(blk, indent_unit, attrs, true)
1006     }
1007
1008     pub fn print_block_maybe_unclosed(&mut self,
1009                                       blk: &hir::Block,
1010                                       indented: usize,
1011                                       attrs: &[ast::Attribute],
1012                                       close_box: bool)
1013                                       -> io::Result<()> {
1014         match blk.rules {
1015             hir::UnsafeBlock(..) => self.word_space("unsafe")?,
1016             hir::PushUnsafeBlock(..) => self.word_space("push_unsafe")?,
1017             hir::PopUnsafeBlock(..) => self.word_space("pop_unsafe")?,
1018             hir::DefaultBlock => (),
1019         }
1020         self.maybe_print_comment(blk.span.lo())?;
1021         self.ann.pre(self, NodeBlock(blk))?;
1022         self.bopen()?;
1023
1024         self.print_inner_attributes(attrs)?;
1025
1026         for st in &blk.stmts {
1027             self.print_stmt(st)?;
1028         }
1029         match blk.expr {
1030             Some(ref expr) => {
1031                 self.space_if_not_bol()?;
1032                 self.print_expr(&expr)?;
1033                 self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()))?;
1034             }
1035             _ => (),
1036         }
1037         self.bclose_maybe_open(blk.span, indented, close_box)?;
1038         self.ann.post(self, NodeBlock(blk))
1039     }
1040
1041     fn print_else(&mut self, els: Option<&hir::Expr>) -> io::Result<()> {
1042         match els {
1043             Some(_else) => {
1044                 match _else.node {
1045                     // "another else-if"
1046                     hir::ExprIf(ref i, ref then, ref e) => {
1047                         self.cbox(indent_unit - 1)?;
1048                         self.ibox(0)?;
1049                         self.s.word(" else if ")?;
1050                         self.print_expr_as_cond(&i)?;
1051                         self.s.space()?;
1052                         self.print_expr(&then)?;
1053                         self.print_else(e.as_ref().map(|e| &**e))
1054                     }
1055                     // "final else"
1056                     hir::ExprBlock(ref b) => {
1057                         self.cbox(indent_unit - 1)?;
1058                         self.ibox(0)?;
1059                         self.s.word(" else ")?;
1060                         self.print_block(&b)
1061                     }
1062                     // BLEAH, constraints would be great here
1063                     _ => {
1064                         panic!("print_if saw if with weird alternative");
1065                     }
1066                 }
1067             }
1068             _ => Ok(()),
1069         }
1070     }
1071
1072     pub fn print_if(&mut self,
1073                     test: &hir::Expr,
1074                     blk: &hir::Expr,
1075                     elseopt: Option<&hir::Expr>)
1076                     -> io::Result<()> {
1077         self.head("if")?;
1078         self.print_expr_as_cond(test)?;
1079         self.s.space()?;
1080         self.print_expr(blk)?;
1081         self.print_else(elseopt)
1082     }
1083
1084     pub fn print_if_let(&mut self,
1085                         pat: &hir::Pat,
1086                         expr: &hir::Expr,
1087                         blk: &hir::Block,
1088                         elseopt: Option<&hir::Expr>)
1089                         -> io::Result<()> {
1090         self.head("if let")?;
1091         self.print_pat(pat)?;
1092         self.s.space()?;
1093         self.word_space("=")?;
1094         self.print_expr_as_cond(expr)?;
1095         self.s.space()?;
1096         self.print_block(blk)?;
1097         self.print_else(elseopt)
1098     }
1099
1100
1101     fn print_call_post(&mut self, args: &[hir::Expr]) -> io::Result<()> {
1102         self.popen()?;
1103         self.commasep_exprs(Inconsistent, args)?;
1104         self.pclose()
1105     }
1106
1107     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr, prec: i8) -> io::Result<()> {
1108         let needs_par = expr_precedence(expr) < prec;
1109         if needs_par {
1110             self.popen()?;
1111         }
1112         self.print_expr(expr)?;
1113         if needs_par {
1114             self.pclose()?;
1115         }
1116         Ok(())
1117     }
1118
1119     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1120     /// `if cond { ... }`.
1121     pub fn print_expr_as_cond(&mut self, expr: &hir::Expr) -> io::Result<()> {
1122         let needs_par = match expr.node {
1123             // These cases need parens due to the parse error observed in #26461: `if return {}`
1124             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1125             hir::ExprClosure(..) |
1126             hir::ExprRet(..) |
1127             hir::ExprBreak(..) => true,
1128
1129             _ => contains_exterior_struct_lit(expr),
1130         };
1131
1132         if needs_par {
1133             self.popen()?;
1134         }
1135         self.print_expr(expr)?;
1136         if needs_par {
1137             self.pclose()?;
1138         }
1139         Ok(())
1140     }
1141
1142     fn print_expr_vec(&mut self, exprs: &[hir::Expr]) -> io::Result<()> {
1143         self.ibox(indent_unit)?;
1144         self.s.word("[")?;
1145         self.commasep_exprs(Inconsistent, exprs)?;
1146         self.s.word("]")?;
1147         self.end()
1148     }
1149
1150     fn print_expr_repeat(&mut self, element: &hir::Expr, count: hir::BodyId) -> io::Result<()> {
1151         self.ibox(indent_unit)?;
1152         self.s.word("[")?;
1153         self.print_expr(element)?;
1154         self.word_space(";")?;
1155         self.ann.nested(self, Nested::Body(count))?;
1156         self.s.word("]")?;
1157         self.end()
1158     }
1159
1160     fn print_expr_struct(&mut self,
1161                          qpath: &hir::QPath,
1162                          fields: &[hir::Field],
1163                          wth: &Option<P<hir::Expr>>)
1164                          -> io::Result<()> {
1165         self.print_qpath(qpath, true)?;
1166         self.s.word("{")?;
1167         self.commasep_cmnt(Consistent,
1168                            &fields[..],
1169                            |s, field| {
1170                                s.ibox(indent_unit)?;
1171                                if !field.is_shorthand {
1172                                     s.print_name(field.name.node)?;
1173                                     s.word_space(":")?;
1174                                }
1175                                s.print_expr(&field.expr)?;
1176                                s.end()
1177                            },
1178                            |f| f.span)?;
1179         match *wth {
1180             Some(ref expr) => {
1181                 self.ibox(indent_unit)?;
1182                 if !fields.is_empty() {
1183                     self.s.word(",")?;
1184                     self.s.space()?;
1185                 }
1186                 self.s.word("..")?;
1187                 self.print_expr(&expr)?;
1188                 self.end()?;
1189             }
1190             _ => if !fields.is_empty() {
1191                 self.s.word(",")?
1192             },
1193         }
1194         self.s.word("}")?;
1195         Ok(())
1196     }
1197
1198     fn print_expr_tup(&mut self, exprs: &[hir::Expr]) -> io::Result<()> {
1199         self.popen()?;
1200         self.commasep_exprs(Inconsistent, exprs)?;
1201         if exprs.len() == 1 {
1202             self.s.word(",")?;
1203         }
1204         self.pclose()
1205     }
1206
1207     fn print_expr_call(&mut self, func: &hir::Expr, args: &[hir::Expr]) -> io::Result<()> {
1208         let prec =
1209             match func.node {
1210                 hir::ExprField(..) |
1211                 hir::ExprTupField(..) => parser::PREC_FORCE_PAREN,
1212                 _ => parser::PREC_POSTFIX,
1213             };
1214
1215         self.print_expr_maybe_paren(func, prec)?;
1216         self.print_call_post(args)
1217     }
1218
1219     fn print_expr_method_call(&mut self,
1220                               segment: &hir::PathSegment,
1221                               args: &[hir::Expr])
1222                               -> io::Result<()> {
1223         let base_args = &args[1..];
1224         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX)?;
1225         self.s.word(".")?;
1226         self.print_name(segment.name)?;
1227
1228         segment.with_parameters(|parameters| {
1229             if !parameters.lifetimes.is_empty() ||
1230                 !parameters.types.is_empty() ||
1231                 !parameters.bindings.is_empty()
1232             {
1233                 self.print_path_parameters(&parameters, segment.infer_types, true)
1234             } else {
1235                 Ok(())
1236             }
1237         })?;
1238         self.print_call_post(base_args)
1239     }
1240
1241     fn print_expr_binary(&mut self,
1242                          op: hir::BinOp,
1243                          lhs: &hir::Expr,
1244                          rhs: &hir::Expr)
1245                          -> io::Result<()> {
1246         let assoc_op = bin_op_to_assoc_op(op.node);
1247         let prec = assoc_op.precedence() as i8;
1248         let fixity = assoc_op.fixity();
1249
1250         let (left_prec, right_prec) = match fixity {
1251             Fixity::Left => (prec, prec + 1),
1252             Fixity::Right => (prec + 1, prec),
1253             Fixity::None => (prec + 1, prec + 1),
1254         };
1255
1256         self.print_expr_maybe_paren(lhs, left_prec)?;
1257         self.s.space()?;
1258         self.word_space(op.node.as_str())?;
1259         self.print_expr_maybe_paren(rhs, right_prec)
1260     }
1261
1262     fn print_expr_unary(&mut self, op: hir::UnOp, expr: &hir::Expr) -> io::Result<()> {
1263         self.s.word(op.as_str())?;
1264         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1265     }
1266
1267     fn print_expr_addr_of(&mut self,
1268                           mutability: hir::Mutability,
1269                           expr: &hir::Expr)
1270                           -> io::Result<()> {
1271         self.s.word("&")?;
1272         self.print_mutability(mutability)?;
1273         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1274     }
1275
1276     pub fn print_expr(&mut self, expr: &hir::Expr) -> io::Result<()> {
1277         self.maybe_print_comment(expr.span.lo())?;
1278         self.print_outer_attributes(&expr.attrs)?;
1279         self.ibox(indent_unit)?;
1280         self.ann.pre(self, NodeExpr(expr))?;
1281         match expr.node {
1282             hir::ExprBox(ref expr) => {
1283                 self.word_space("box")?;
1284                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)?;
1285             }
1286             hir::ExprArray(ref exprs) => {
1287                 self.print_expr_vec(exprs)?;
1288             }
1289             hir::ExprRepeat(ref element, count) => {
1290                 self.print_expr_repeat(&element, count)?;
1291             }
1292             hir::ExprStruct(ref qpath, ref fields, ref wth) => {
1293                 self.print_expr_struct(qpath, &fields[..], wth)?;
1294             }
1295             hir::ExprTup(ref exprs) => {
1296                 self.print_expr_tup(exprs)?;
1297             }
1298             hir::ExprCall(ref func, ref args) => {
1299                 self.print_expr_call(&func, args)?;
1300             }
1301             hir::ExprMethodCall(ref segment, _, ref args) => {
1302                 self.print_expr_method_call(segment, args)?;
1303             }
1304             hir::ExprBinary(op, ref lhs, ref rhs) => {
1305                 self.print_expr_binary(op, &lhs, &rhs)?;
1306             }
1307             hir::ExprUnary(op, ref expr) => {
1308                 self.print_expr_unary(op, &expr)?;
1309             }
1310             hir::ExprAddrOf(m, ref expr) => {
1311                 self.print_expr_addr_of(m, &expr)?;
1312             }
1313             hir::ExprLit(ref lit) => {
1314                 self.print_literal(&lit)?;
1315             }
1316             hir::ExprCast(ref expr, ref ty) => {
1317                 let prec = AssocOp::As.precedence() as i8;
1318                 self.print_expr_maybe_paren(&expr, prec)?;
1319                 self.s.space()?;
1320                 self.word_space("as")?;
1321                 self.print_type(&ty)?;
1322             }
1323             hir::ExprType(ref expr, ref ty) => {
1324                 let prec = AssocOp::Colon.precedence() as i8;
1325                 self.print_expr_maybe_paren(&expr, prec)?;
1326                 self.word_space(":")?;
1327                 self.print_type(&ty)?;
1328             }
1329             hir::ExprIf(ref test, ref blk, ref elseopt) => {
1330                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e))?;
1331             }
1332             hir::ExprWhile(ref test, ref blk, opt_sp_name) => {
1333                 if let Some(sp_name) = opt_sp_name {
1334                     self.print_name(sp_name.node)?;
1335                     self.word_space(":")?;
1336                 }
1337                 self.head("while")?;
1338                 self.print_expr_as_cond(&test)?;
1339                 self.s.space()?;
1340                 self.print_block(&blk)?;
1341             }
1342             hir::ExprLoop(ref blk, opt_sp_name, _) => {
1343                 if let Some(sp_name) = opt_sp_name {
1344                     self.print_name(sp_name.node)?;
1345                     self.word_space(":")?;
1346                 }
1347                 self.head("loop")?;
1348                 self.s.space()?;
1349                 self.print_block(&blk)?;
1350             }
1351             hir::ExprMatch(ref expr, ref arms, _) => {
1352                 self.cbox(indent_unit)?;
1353                 self.ibox(4)?;
1354                 self.word_nbsp("match")?;
1355                 self.print_expr_as_cond(&expr)?;
1356                 self.s.space()?;
1357                 self.bopen()?;
1358                 for arm in arms {
1359                     self.print_arm(arm)?;
1360                 }
1361                 self.bclose_(expr.span, indent_unit)?;
1362             }
1363             hir::ExprClosure(capture_clause, ref decl, body, _fn_decl_span, _gen) => {
1364                 self.print_capture_clause(capture_clause)?;
1365
1366                 self.print_closure_args(&decl, body)?;
1367                 self.s.space()?;
1368
1369                 // this is a bare expression
1370                 self.ann.nested(self, Nested::Body(body))?;
1371                 self.end()?; // need to close a box
1372
1373                 // a box will be closed by print_expr, but we didn't want an overall
1374                 // wrapper so we closed the corresponding opening. so create an
1375                 // empty box to satisfy the close.
1376                 self.ibox(0)?;
1377             }
1378             hir::ExprBlock(ref blk) => {
1379                 // containing cbox, will be closed by print-block at }
1380                 self.cbox(indent_unit)?;
1381                 // head-box, will be closed by print-block after {
1382                 self.ibox(0)?;
1383                 self.print_block(&blk)?;
1384             }
1385             hir::ExprAssign(ref lhs, ref rhs) => {
1386                 let prec = AssocOp::Assign.precedence() as i8;
1387                 self.print_expr_maybe_paren(&lhs, prec + 1)?;
1388                 self.s.space()?;
1389                 self.word_space("=")?;
1390                 self.print_expr_maybe_paren(&rhs, prec)?;
1391             }
1392             hir::ExprAssignOp(op, ref lhs, ref rhs) => {
1393                 let prec = AssocOp::Assign.precedence() as i8;
1394                 self.print_expr_maybe_paren(&lhs, prec + 1)?;
1395                 self.s.space()?;
1396                 self.s.word(op.node.as_str())?;
1397                 self.word_space("=")?;
1398                 self.print_expr_maybe_paren(&rhs, prec)?;
1399             }
1400             hir::ExprField(ref expr, name) => {
1401                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX)?;
1402                 self.s.word(".")?;
1403                 self.print_name(name.node)?;
1404             }
1405             hir::ExprTupField(ref expr, id) => {
1406                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX)?;
1407                 self.s.word(".")?;
1408                 self.print_usize(id.node)?;
1409             }
1410             hir::ExprIndex(ref expr, ref index) => {
1411                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX)?;
1412                 self.s.word("[")?;
1413                 self.print_expr(&index)?;
1414                 self.s.word("]")?;
1415             }
1416             hir::ExprPath(ref qpath) => {
1417                 self.print_qpath(qpath, true)?
1418             }
1419             hir::ExprBreak(label, ref opt_expr) => {
1420                 self.s.word("break")?;
1421                 self.s.space()?;
1422                 if let Some(label_ident) = label.ident {
1423                     self.print_name(label_ident.node.name)?;
1424                     self.s.space()?;
1425                 }
1426                 if let Some(ref expr) = *opt_expr {
1427                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP)?;
1428                     self.s.space()?;
1429                 }
1430             }
1431             hir::ExprAgain(label) => {
1432                 self.s.word("continue")?;
1433                 self.s.space()?;
1434                 if let Some(label_ident) = label.ident {
1435                     self.print_name(label_ident.node.name)?;
1436                     self.s.space()?
1437                 }
1438             }
1439             hir::ExprRet(ref result) => {
1440                 self.s.word("return")?;
1441                 match *result {
1442                     Some(ref expr) => {
1443                         self.s.word(" ")?;
1444                         self.print_expr_maybe_paren(&expr, parser::PREC_JUMP)?;
1445                     }
1446                     _ => (),
1447                 }
1448             }
1449             hir::ExprInlineAsm(ref a, ref outputs, ref inputs) => {
1450                 self.s.word("asm!")?;
1451                 self.popen()?;
1452                 self.print_string(&a.asm.as_str(), a.asm_str_style)?;
1453                 self.word_space(":")?;
1454
1455                 let mut out_idx = 0;
1456                 self.commasep(Inconsistent, &a.outputs, |s, out| {
1457                     let constraint = out.constraint.as_str();
1458                     let mut ch = constraint.chars();
1459                     match ch.next() {
1460                         Some('=') if out.is_rw => {
1461                             s.print_string(&format!("+{}", ch.as_str()),
1462                                            ast::StrStyle::Cooked)?
1463                         }
1464                         _ => s.print_string(&constraint, ast::StrStyle::Cooked)?,
1465                     }
1466                     s.popen()?;
1467                     s.print_expr(&outputs[out_idx])?;
1468                     s.pclose()?;
1469                     out_idx += 1;
1470                     Ok(())
1471                 })?;
1472                 self.s.space()?;
1473                 self.word_space(":")?;
1474
1475                 let mut in_idx = 0;
1476                 self.commasep(Inconsistent, &a.inputs, |s, co| {
1477                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
1478                     s.popen()?;
1479                     s.print_expr(&inputs[in_idx])?;
1480                     s.pclose()?;
1481                     in_idx += 1;
1482                     Ok(())
1483                 })?;
1484                 self.s.space()?;
1485                 self.word_space(":")?;
1486
1487                 self.commasep(Inconsistent, &a.clobbers, |s, co| {
1488                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
1489                     Ok(())
1490                 })?;
1491
1492                 let mut options = vec![];
1493                 if a.volatile {
1494                     options.push("volatile");
1495                 }
1496                 if a.alignstack {
1497                     options.push("alignstack");
1498                 }
1499                 if a.dialect == ast::AsmDialect::Intel {
1500                     options.push("intel");
1501                 }
1502
1503                 if !options.is_empty() {
1504                     self.s.space()?;
1505                     self.word_space(":")?;
1506                     self.commasep(Inconsistent, &options, |s, &co| {
1507                         s.print_string(co, ast::StrStyle::Cooked)?;
1508                         Ok(())
1509                     })?;
1510                 }
1511
1512                 self.pclose()?;
1513             }
1514             hir::ExprYield(ref expr) => {
1515                 self.word_space("yield")?;
1516                 self.print_expr_maybe_paren(&expr, parser::PREC_JUMP)?;
1517             }
1518         }
1519         self.ann.post(self, NodeExpr(expr))?;
1520         self.end()
1521     }
1522
1523     pub fn print_local_decl(&mut self, loc: &hir::Local) -> io::Result<()> {
1524         self.print_pat(&loc.pat)?;
1525         if let Some(ref ty) = loc.ty {
1526             self.word_space(":")?;
1527             self.print_type(&ty)?;
1528         }
1529         Ok(())
1530     }
1531
1532     pub fn print_decl(&mut self, decl: &hir::Decl) -> io::Result<()> {
1533         self.maybe_print_comment(decl.span.lo())?;
1534         match decl.node {
1535             hir::DeclLocal(ref loc) => {
1536                 self.space_if_not_bol()?;
1537                 self.ibox(indent_unit)?;
1538                 self.word_nbsp("let")?;
1539
1540                 self.ibox(indent_unit)?;
1541                 self.print_local_decl(&loc)?;
1542                 self.end()?;
1543                 if let Some(ref init) = loc.init {
1544                     self.nbsp()?;
1545                     self.word_space("=")?;
1546                     self.print_expr(&init)?;
1547                 }
1548                 self.end()
1549             }
1550             hir::DeclItem(item) => {
1551                 self.ann.nested(self, Nested::Item(item))
1552             }
1553         }
1554     }
1555
1556     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
1557         self.s.word(&i.to_string())
1558     }
1559
1560     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
1561         self.s.word(&name.as_str())?;
1562         self.ann.post(self, NodeName(&name))
1563     }
1564
1565     pub fn print_for_decl(&mut self, loc: &hir::Local, coll: &hir::Expr) -> io::Result<()> {
1566         self.print_local_decl(loc)?;
1567         self.s.space()?;
1568         self.word_space("in")?;
1569         self.print_expr(coll)
1570     }
1571
1572     pub fn print_path(&mut self,
1573                       path: &hir::Path,
1574                       colons_before_params: bool)
1575                       -> io::Result<()> {
1576         self.maybe_print_comment(path.span.lo())?;
1577
1578         for (i, segment) in path.segments.iter().enumerate() {
1579             if i > 0 {
1580                 self.s.word("::")?
1581             }
1582             if segment.name != keywords::CrateRoot.name() &&
1583                segment.name != keywords::DollarCrate.name() {
1584                self.print_name(segment.name)?;
1585                segment.with_parameters(|parameters| {
1586                    self.print_path_parameters(parameters,
1587                                               segment.infer_types,
1588                                               colons_before_params)
1589                })?;
1590             }
1591         }
1592
1593         Ok(())
1594     }
1595
1596     pub fn print_qpath(&mut self,
1597                        qpath: &hir::QPath,
1598                        colons_before_params: bool)
1599                        -> io::Result<()> {
1600         match *qpath {
1601             hir::QPath::Resolved(None, ref path) => {
1602                 self.print_path(path, colons_before_params)
1603             }
1604             hir::QPath::Resolved(Some(ref qself), ref path) => {
1605                 self.s.word("<")?;
1606                 self.print_type(qself)?;
1607                 self.s.space()?;
1608                 self.word_space("as")?;
1609
1610                 for (i, segment) in path.segments[..path.segments.len() - 1].iter().enumerate() {
1611                     if i > 0 {
1612                         self.s.word("::")?
1613                     }
1614                     if segment.name != keywords::CrateRoot.name() &&
1615                        segment.name != keywords::DollarCrate.name() {
1616                         self.print_name(segment.name)?;
1617                         segment.with_parameters(|parameters| {
1618                             self.print_path_parameters(parameters,
1619                                                        segment.infer_types,
1620                                                        colons_before_params)
1621                         })?;
1622                     }
1623                 }
1624
1625                 self.s.word(">")?;
1626                 self.s.word("::")?;
1627                 let item_segment = path.segments.last().unwrap();
1628                 self.print_name(item_segment.name)?;
1629                 item_segment.with_parameters(|parameters| {
1630                     self.print_path_parameters(parameters,
1631                                                item_segment.infer_types,
1632                                                colons_before_params)
1633                 })
1634             }
1635             hir::QPath::TypeRelative(ref qself, ref item_segment) => {
1636                 self.s.word("<")?;
1637                 self.print_type(qself)?;
1638                 self.s.word(">")?;
1639                 self.s.word("::")?;
1640                 self.print_name(item_segment.name)?;
1641                 item_segment.with_parameters(|parameters| {
1642                     self.print_path_parameters(parameters,
1643                                                item_segment.infer_types,
1644                                                colons_before_params)
1645                 })
1646             }
1647         }
1648     }
1649
1650     fn print_path_parameters(&mut self,
1651                              parameters: &hir::PathParameters,
1652                              infer_types: bool,
1653                              colons_before_params: bool)
1654                              -> io::Result<()> {
1655         if parameters.parenthesized {
1656             self.s.word("(")?;
1657             self.commasep(Inconsistent, parameters.inputs(), |s, ty| s.print_type(&ty))?;
1658             self.s.word(")")?;
1659
1660             self.space_if_not_bol()?;
1661             self.word_space("->")?;
1662             self.print_type(&parameters.bindings[0].ty)?;
1663         } else {
1664             let start = if colons_before_params { "::<" } else { "<" };
1665             let empty = Cell::new(true);
1666             let start_or_comma = |this: &mut Self| {
1667                 if empty.get() {
1668                     empty.set(false);
1669                     this.s.word(start)
1670                 } else {
1671                     this.word_space(",")
1672                 }
1673             };
1674
1675             if !parameters.lifetimes.iter().all(|lt| lt.is_elided()) {
1676                 for lifetime in &parameters.lifetimes {
1677                     start_or_comma(self)?;
1678                     self.print_lifetime(lifetime)?;
1679                 }
1680             }
1681
1682             if !parameters.types.is_empty() {
1683                 start_or_comma(self)?;
1684                 self.commasep(Inconsistent, &parameters.types, |s, ty| s.print_type(&ty))?;
1685             }
1686
1687             // FIXME(eddyb) This would leak into error messages, e.g.:
1688             // "non-exhaustive patterns: `Some::<..>(_)` not covered".
1689             if infer_types && false {
1690                 start_or_comma(self)?;
1691                 self.s.word("..")?;
1692             }
1693
1694             for binding in parameters.bindings.iter() {
1695                 start_or_comma(self)?;
1696                 self.print_name(binding.name)?;
1697                 self.s.space()?;
1698                 self.word_space("=")?;
1699                 self.print_type(&binding.ty)?;
1700             }
1701
1702             if !empty.get() {
1703                 self.s.word(">")?
1704             }
1705         }
1706
1707         Ok(())
1708     }
1709
1710     pub fn print_pat(&mut self, pat: &hir::Pat) -> io::Result<()> {
1711         self.maybe_print_comment(pat.span.lo())?;
1712         self.ann.pre(self, NodePat(pat))?;
1713         // Pat isn't normalized, but the beauty of it
1714         // is that it doesn't matter
1715         match pat.node {
1716             PatKind::Wild => self.s.word("_")?,
1717             PatKind::Binding(binding_mode, _, ref path1, ref sub) => {
1718                 match binding_mode {
1719                     hir::BindingAnnotation::Ref => {
1720                         self.word_nbsp("ref")?;
1721                         self.print_mutability(hir::MutImmutable)?;
1722                     }
1723                     hir::BindingAnnotation::RefMut => {
1724                         self.word_nbsp("ref")?;
1725                         self.print_mutability(hir::MutMutable)?;
1726                     }
1727                     hir::BindingAnnotation::Unannotated => {}
1728                     hir::BindingAnnotation::Mutable => {
1729                         self.word_nbsp("mut")?;
1730                     }
1731                 }
1732                 self.print_name(path1.node)?;
1733                 if let Some(ref p) = *sub {
1734                     self.s.word("@")?;
1735                     self.print_pat(&p)?;
1736                 }
1737             }
1738             PatKind::TupleStruct(ref qpath, ref elts, ddpos) => {
1739                 self.print_qpath(qpath, true)?;
1740                 self.popen()?;
1741                 if let Some(ddpos) = ddpos {
1742                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
1743                     if ddpos != 0 {
1744                         self.word_space(",")?;
1745                     }
1746                     self.s.word("..")?;
1747                     if ddpos != elts.len() {
1748                         self.s.word(",")?;
1749                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
1750                     }
1751                 } else {
1752                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
1753                 }
1754                 self.pclose()?;
1755             }
1756             PatKind::Path(ref qpath) => {
1757                 self.print_qpath(qpath, true)?;
1758             }
1759             PatKind::Struct(ref qpath, ref fields, etc) => {
1760                 self.print_qpath(qpath, true)?;
1761                 self.nbsp()?;
1762                 self.word_space("{")?;
1763                 self.commasep_cmnt(Consistent,
1764                                    &fields[..],
1765                                    |s, f| {
1766                                        s.cbox(indent_unit)?;
1767                                        if !f.node.is_shorthand {
1768                                            s.print_name(f.node.name)?;
1769                                            s.word_nbsp(":")?;
1770                                        }
1771                                        s.print_pat(&f.node.pat)?;
1772                                        s.end()
1773                                    },
1774                                    |f| f.node.pat.span)?;
1775                 if etc {
1776                     if !fields.is_empty() {
1777                         self.word_space(",")?;
1778                     }
1779                     self.s.word("..")?;
1780                 }
1781                 self.s.space()?;
1782                 self.s.word("}")?;
1783             }
1784             PatKind::Tuple(ref elts, ddpos) => {
1785                 self.popen()?;
1786                 if let Some(ddpos) = ddpos {
1787                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
1788                     if ddpos != 0 {
1789                         self.word_space(",")?;
1790                     }
1791                     self.s.word("..")?;
1792                     if ddpos != elts.len() {
1793                         self.s.word(",")?;
1794                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
1795                     }
1796                 } else {
1797                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
1798                     if elts.len() == 1 {
1799                         self.s.word(",")?;
1800                     }
1801                 }
1802                 self.pclose()?;
1803             }
1804             PatKind::Box(ref inner) => {
1805                 self.s.word("box ")?;
1806                 self.print_pat(&inner)?;
1807             }
1808             PatKind::Ref(ref inner, mutbl) => {
1809                 self.s.word("&")?;
1810                 if mutbl == hir::MutMutable {
1811                     self.s.word("mut ")?;
1812                 }
1813                 self.print_pat(&inner)?;
1814             }
1815             PatKind::Lit(ref e) => self.print_expr(&e)?,
1816             PatKind::Range(ref begin, ref end, ref end_kind) => {
1817                 self.print_expr(&begin)?;
1818                 self.s.space()?;
1819                 match *end_kind {
1820                     RangeEnd::Included => self.s.word("...")?,
1821                     RangeEnd::Excluded => self.s.word("..")?,
1822                 }
1823                 self.print_expr(&end)?;
1824             }
1825             PatKind::Slice(ref before, ref slice, ref after) => {
1826                 self.s.word("[")?;
1827                 self.commasep(Inconsistent, &before[..], |s, p| s.print_pat(&p))?;
1828                 if let Some(ref p) = *slice {
1829                     if !before.is_empty() {
1830                         self.word_space(",")?;
1831                     }
1832                     if p.node != PatKind::Wild {
1833                         self.print_pat(&p)?;
1834                     }
1835                     self.s.word("..")?;
1836                     if !after.is_empty() {
1837                         self.word_space(",")?;
1838                     }
1839                 }
1840                 self.commasep(Inconsistent, &after[..], |s, p| s.print_pat(&p))?;
1841                 self.s.word("]")?;
1842             }
1843         }
1844         self.ann.post(self, NodePat(pat))
1845     }
1846
1847     fn print_arm(&mut self, arm: &hir::Arm) -> io::Result<()> {
1848         // I have no idea why this check is necessary, but here it
1849         // is :(
1850         if arm.attrs.is_empty() {
1851             self.s.space()?;
1852         }
1853         self.cbox(indent_unit)?;
1854         self.ibox(0)?;
1855         self.print_outer_attributes(&arm.attrs)?;
1856         let mut first = true;
1857         for p in &arm.pats {
1858             if first {
1859                 first = false;
1860             } else {
1861                 self.s.space()?;
1862                 self.word_space("|")?;
1863             }
1864             self.print_pat(&p)?;
1865         }
1866         self.s.space()?;
1867         if let Some(ref e) = arm.guard {
1868             self.word_space("if")?;
1869             self.print_expr(&e)?;
1870             self.s.space()?;
1871         }
1872         self.word_space("=>")?;
1873
1874         match arm.body.node {
1875             hir::ExprBlock(ref blk) => {
1876                 // the block will close the pattern's ibox
1877                 self.print_block_unclosed_indent(&blk, indent_unit)?;
1878
1879                 // If it is a user-provided unsafe block, print a comma after it
1880                 if let hir::UnsafeBlock(hir::UserProvided) = blk.rules {
1881                     self.s.word(",")?;
1882                 }
1883             }
1884             _ => {
1885                 self.end()?; // close the ibox for the pattern
1886                 self.print_expr(&arm.body)?;
1887                 self.s.word(",")?;
1888             }
1889         }
1890         self.end() // close enclosing cbox
1891     }
1892
1893     pub fn print_fn(&mut self,
1894                     decl: &hir::FnDecl,
1895                     unsafety: hir::Unsafety,
1896                     constness: hir::Constness,
1897                     abi: Abi,
1898                     name: Option<ast::Name>,
1899                     generics: &hir::Generics,
1900                     vis: &hir::Visibility,
1901                     arg_names: &[Spanned<ast::Name>],
1902                     body_id: Option<hir::BodyId>)
1903                     -> io::Result<()> {
1904         self.print_fn_header_info(unsafety, constness, abi, vis)?;
1905
1906         if let Some(name) = name {
1907             self.nbsp()?;
1908             self.print_name(name)?;
1909         }
1910         self.print_generics(generics)?;
1911
1912         self.popen()?;
1913         let mut i = 0;
1914         // Make sure we aren't supplied *both* `arg_names` and `body_id`.
1915         assert!(arg_names.is_empty() || body_id.is_none());
1916         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
1917             s.ibox(indent_unit)?;
1918             if let Some(name) = arg_names.get(i) {
1919                 s.s.word(&name.node.as_str())?;
1920                 s.s.word(":")?;
1921                 s.s.space()?;
1922             } else if let Some(body_id) = body_id {
1923                 s.ann.nested(s, Nested::BodyArgPat(body_id, i))?;
1924                 s.s.word(":")?;
1925                 s.s.space()?;
1926             }
1927             i += 1;
1928             s.print_type(ty)?;
1929             s.end()
1930         })?;
1931         if decl.variadic {
1932             self.s.word(", ...")?;
1933         }
1934         self.pclose()?;
1935
1936         self.print_fn_output(decl)?;
1937         self.print_where_clause(&generics.where_clause)
1938     }
1939
1940     fn print_closure_args(&mut self, decl: &hir::FnDecl, body_id: hir::BodyId) -> io::Result<()> {
1941         self.s.word("|")?;
1942         let mut i = 0;
1943         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
1944             s.ibox(indent_unit)?;
1945
1946             s.ann.nested(s, Nested::BodyArgPat(body_id, i))?;
1947             i += 1;
1948
1949             if ty.node != hir::TyInfer {
1950                 s.s.word(":")?;
1951                 s.s.space()?;
1952                 s.print_type(ty)?;
1953             }
1954             s.end()
1955         })?;
1956         self.s.word("|")?;
1957
1958         if let hir::DefaultReturn(..) = decl.output {
1959             return Ok(());
1960         }
1961
1962         self.space_if_not_bol()?;
1963         self.word_space("->")?;
1964         match decl.output {
1965             hir::Return(ref ty) => {
1966                 self.print_type(&ty)?;
1967                 self.maybe_print_comment(ty.span.lo())
1968             }
1969             hir::DefaultReturn(..) => unreachable!(),
1970         }
1971     }
1972
1973     pub fn print_capture_clause(&mut self, capture_clause: hir::CaptureClause) -> io::Result<()> {
1974         match capture_clause {
1975             hir::CaptureByValue => self.word_space("move"),
1976             hir::CaptureByRef => Ok(()),
1977         }
1978     }
1979
1980     pub fn print_bounds(&mut self, prefix: &str, bounds: &[hir::TyParamBound]) -> io::Result<()> {
1981         if !bounds.is_empty() {
1982             self.s.word(prefix)?;
1983             let mut first = true;
1984             for bound in bounds {
1985                 self.nbsp()?;
1986                 if first {
1987                     first = false;
1988                 } else {
1989                     self.word_space("+")?;
1990                 }
1991
1992                 match *bound {
1993                     TraitTyParamBound(ref tref, TraitBoundModifier::None) => {
1994                         self.print_poly_trait_ref(tref)
1995                     }
1996                     TraitTyParamBound(ref tref, TraitBoundModifier::Maybe) => {
1997                         self.s.word("?")?;
1998                         self.print_poly_trait_ref(tref)
1999                     }
2000                     RegionTyParamBound(ref lt) => {
2001                         self.print_lifetime(lt)
2002                     }
2003                 }?
2004             }
2005             Ok(())
2006         } else {
2007             Ok(())
2008         }
2009     }
2010
2011     pub fn print_lifetime(&mut self, lifetime: &hir::Lifetime) -> io::Result<()> {
2012         self.print_name(lifetime.name.name())
2013     }
2014
2015     pub fn print_lifetime_def(&mut self, lifetime: &hir::LifetimeDef) -> io::Result<()> {
2016         self.print_lifetime(&lifetime.lifetime)?;
2017         let mut sep = ":";
2018         for v in &lifetime.bounds {
2019             self.s.word(sep)?;
2020             self.print_lifetime(v)?;
2021             sep = "+";
2022         }
2023         Ok(())
2024     }
2025
2026     pub fn print_generics(&mut self, generics: &hir::Generics) -> io::Result<()> {
2027         let total = generics.lifetimes.len() + generics.ty_params.len();
2028         if total == 0 {
2029             return Ok(());
2030         }
2031
2032         self.s.word("<")?;
2033
2034         let mut ints = Vec::new();
2035         for i in 0..total {
2036             ints.push(i);
2037         }
2038
2039         self.commasep(Inconsistent, &ints[..], |s, &idx| {
2040             if idx < generics.lifetimes.len() {
2041                 let lifetime = &generics.lifetimes[idx];
2042                 s.print_lifetime_def(lifetime)
2043             } else {
2044                 let idx = idx - generics.lifetimes.len();
2045                 let param = &generics.ty_params[idx];
2046                 s.print_ty_param(param)
2047             }
2048         })?;
2049
2050         self.s.word(">")?;
2051         Ok(())
2052     }
2053
2054     pub fn print_ty_param(&mut self, param: &hir::TyParam) -> io::Result<()> {
2055         self.print_name(param.name)?;
2056         self.print_bounds(":", &param.bounds)?;
2057         match param.default {
2058             Some(ref default) => {
2059                 self.s.space()?;
2060                 self.word_space("=")?;
2061                 self.print_type(&default)
2062             }
2063             _ => Ok(()),
2064         }
2065     }
2066
2067     pub fn print_where_clause(&mut self, where_clause: &hir::WhereClause) -> io::Result<()> {
2068         if where_clause.predicates.is_empty() {
2069             return Ok(());
2070         }
2071
2072         self.s.space()?;
2073         self.word_space("where")?;
2074
2075         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2076             if i != 0 {
2077                 self.word_space(",")?;
2078             }
2079
2080             match predicate {
2081                 &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate{ref bound_lifetimes,
2082                                                                               ref bounded_ty,
2083                                                                               ref bounds,
2084                                                                               ..}) => {
2085                     self.print_formal_lifetime_list(bound_lifetimes)?;
2086                     self.print_type(&bounded_ty)?;
2087                     self.print_bounds(":", bounds)?;
2088                 }
2089                 &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate{ref lifetime,
2090                                                                                 ref bounds,
2091                                                                                 ..}) => {
2092                     self.print_lifetime(lifetime)?;
2093                     self.s.word(":")?;
2094
2095                     for (i, bound) in bounds.iter().enumerate() {
2096                         self.print_lifetime(bound)?;
2097
2098                         if i != 0 {
2099                             self.s.word(":")?;
2100                         }
2101                     }
2102                 }
2103                 &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate{ref lhs_ty,
2104                                                                         ref rhs_ty,
2105                                                                         ..}) => {
2106                     self.print_type(lhs_ty)?;
2107                     self.s.space()?;
2108                     self.word_space("=")?;
2109                     self.print_type(rhs_ty)?;
2110                 }
2111             }
2112         }
2113
2114         Ok(())
2115     }
2116
2117     pub fn print_mutability(&mut self, mutbl: hir::Mutability) -> io::Result<()> {
2118         match mutbl {
2119             hir::MutMutable => self.word_nbsp("mut"),
2120             hir::MutImmutable => Ok(()),
2121         }
2122     }
2123
2124     pub fn print_mt(&mut self, mt: &hir::MutTy) -> io::Result<()> {
2125         self.print_mutability(mt.mutbl)?;
2126         self.print_type(&mt.ty)
2127     }
2128
2129     pub fn print_fn_output(&mut self, decl: &hir::FnDecl) -> io::Result<()> {
2130         if let hir::DefaultReturn(..) = decl.output {
2131             return Ok(());
2132         }
2133
2134         self.space_if_not_bol()?;
2135         self.ibox(indent_unit)?;
2136         self.word_space("->")?;
2137         match decl.output {
2138             hir::DefaultReturn(..) => unreachable!(),
2139             hir::Return(ref ty) => self.print_type(&ty)?,
2140         }
2141         self.end()?;
2142
2143         match decl.output {
2144             hir::Return(ref output) => self.maybe_print_comment(output.span.lo()),
2145             _ => Ok(()),
2146         }
2147     }
2148
2149     pub fn print_ty_fn(&mut self,
2150                        abi: Abi,
2151                        unsafety: hir::Unsafety,
2152                        decl: &hir::FnDecl,
2153                        name: Option<ast::Name>,
2154                        generics: &hir::Generics,
2155                        arg_names: &[Spanned<ast::Name>])
2156                        -> io::Result<()> {
2157         self.ibox(indent_unit)?;
2158         if !generics.lifetimes.is_empty() || !generics.ty_params.is_empty() {
2159             self.s.word("for")?;
2160             self.print_generics(generics)?;
2161         }
2162         let generics = hir::Generics {
2163             lifetimes: hir::HirVec::new(),
2164             ty_params: hir::HirVec::new(),
2165             where_clause: hir::WhereClause {
2166                 id: ast::DUMMY_NODE_ID,
2167                 predicates: hir::HirVec::new(),
2168             },
2169             span: syntax_pos::DUMMY_SP,
2170         };
2171         self.print_fn(decl,
2172                       unsafety,
2173                       hir::Constness::NotConst,
2174                       abi,
2175                       name,
2176                       &generics,
2177                       &hir::Inherited,
2178                       arg_names,
2179                       None)?;
2180         self.end()
2181     }
2182
2183     pub fn maybe_print_trailing_comment(&mut self,
2184                                         span: syntax_pos::Span,
2185                                         next_pos: Option<BytePos>)
2186                                         -> io::Result<()> {
2187         let cm = match self.cm {
2188             Some(cm) => cm,
2189             _ => return Ok(()),
2190         };
2191         if let Some(ref cmnt) = self.next_comment() {
2192             if (*cmnt).style != comments::Trailing {
2193                 return Ok(());
2194             }
2195             let span_line = cm.lookup_char_pos(span.hi());
2196             let comment_line = cm.lookup_char_pos((*cmnt).pos);
2197             let mut next = (*cmnt).pos + BytePos(1);
2198             if let Some(p) = next_pos {
2199                 next = p;
2200             }
2201             if span.hi() < (*cmnt).pos && (*cmnt).pos < next &&
2202                span_line.line == comment_line.line {
2203                 self.print_comment(cmnt)?;
2204             }
2205         }
2206         Ok(())
2207     }
2208
2209     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
2210         // If there aren't any remaining comments, then we need to manually
2211         // make sure there is a line break at the end.
2212         if self.next_comment().is_none() {
2213             self.s.hardbreak()?;
2214         }
2215         loop {
2216             match self.next_comment() {
2217                 Some(ref cmnt) => {
2218                     self.print_comment(cmnt)?;
2219                 }
2220                 _ => break,
2221             }
2222         }
2223         Ok(())
2224     }
2225
2226     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
2227                                                   opt_abi: Option<Abi>)
2228                                                   -> io::Result<()> {
2229         match opt_abi {
2230             Some(Abi::Rust) => Ok(()),
2231             Some(abi) => {
2232                 self.word_nbsp("extern")?;
2233                 self.word_nbsp(&abi.to_string())
2234             }
2235             None => Ok(()),
2236         }
2237     }
2238
2239     pub fn print_extern_opt_abi(&mut self, opt_abi: Option<Abi>) -> io::Result<()> {
2240         match opt_abi {
2241             Some(abi) => {
2242                 self.word_nbsp("extern")?;
2243                 self.word_nbsp(&abi.to_string())
2244             }
2245             None => Ok(()),
2246         }
2247     }
2248
2249     pub fn print_fn_header_info(&mut self,
2250                                 unsafety: hir::Unsafety,
2251                                 constness: hir::Constness,
2252                                 abi: Abi,
2253                                 vis: &hir::Visibility)
2254                                 -> io::Result<()> {
2255         self.s.word(&visibility_qualified(vis, ""))?;
2256         self.print_unsafety(unsafety)?;
2257
2258         match constness {
2259             hir::Constness::NotConst => {}
2260             hir::Constness::Const => self.word_nbsp("const")?,
2261         }
2262
2263         if abi != Abi::Rust {
2264             self.word_nbsp("extern")?;
2265             self.word_nbsp(&abi.to_string())?;
2266         }
2267
2268         self.s.word("fn")
2269     }
2270
2271     pub fn print_unsafety(&mut self, s: hir::Unsafety) -> io::Result<()> {
2272         match s {
2273             hir::Unsafety::Normal => Ok(()),
2274             hir::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2275         }
2276     }
2277 }
2278
2279 // Dup'ed from parse::classify, but adapted for the HIR.
2280 /// Does this expression require a semicolon to be treated
2281 /// as a statement? The negation of this: 'can this expression
2282 /// be used as a statement without a semicolon' -- is used
2283 /// as an early-bail-out in the parser so that, for instance,
2284 ///     if true {...} else {...}
2285 ///      |x| 5
2286 /// isn't parsed as (if true {...} else {...} | x) | 5
2287 fn expr_requires_semi_to_be_stmt(e: &hir::Expr) -> bool {
2288     match e.node {
2289         hir::ExprIf(..) |
2290         hir::ExprMatch(..) |
2291         hir::ExprBlock(_) |
2292         hir::ExprWhile(..) |
2293         hir::ExprLoop(..) => false,
2294         _ => true,
2295     }
2296 }
2297
2298 /// this statement requires a semicolon after it.
2299 /// note that in one case (stmt_semi), we've already
2300 /// seen the semicolon, and thus don't need another.
2301 fn stmt_ends_with_semi(stmt: &hir::Stmt_) -> bool {
2302     match *stmt {
2303         hir::StmtDecl(ref d, _) => {
2304             match d.node {
2305                 hir::DeclLocal(_) => true,
2306                 hir::DeclItem(_) => false,
2307             }
2308         }
2309         hir::StmtExpr(ref e, _) => {
2310             expr_requires_semi_to_be_stmt(&e)
2311         }
2312         hir::StmtSemi(..) => {
2313             false
2314         }
2315     }
2316 }
2317
2318
2319 fn expr_precedence(expr: &hir::Expr) -> i8 {
2320     use syntax::util::parser::*;
2321
2322     match expr.node {
2323         hir::ExprClosure(..) => PREC_CLOSURE,
2324
2325         hir::ExprBreak(..) |
2326         hir::ExprAgain(..) |
2327         hir::ExprRet(..) |
2328         hir::ExprYield(..) => PREC_JUMP,
2329
2330         // Binop-like expr kinds, handled by `AssocOp`.
2331         hir::ExprBinary(op, _, _) => bin_op_to_assoc_op(op.node).precedence() as i8,
2332
2333         hir::ExprCast(..) => AssocOp::As.precedence() as i8,
2334         hir::ExprType(..) => AssocOp::Colon.precedence() as i8,
2335
2336         hir::ExprAssign(..) |
2337         hir::ExprAssignOp(..) => AssocOp::Assign.precedence() as i8,
2338
2339         // Unary, prefix
2340         hir::ExprBox(..) |
2341         hir::ExprAddrOf(..) |
2342         hir::ExprUnary(..) => PREC_PREFIX,
2343
2344         // Unary, postfix
2345         hir::ExprCall(..) |
2346         hir::ExprMethodCall(..) |
2347         hir::ExprField(..) |
2348         hir::ExprTupField(..) |
2349         hir::ExprIndex(..) |
2350         hir::ExprInlineAsm(..) => PREC_POSTFIX,
2351
2352         // Never need parens
2353         hir::ExprArray(..) |
2354         hir::ExprRepeat(..) |
2355         hir::ExprTup(..) |
2356         hir::ExprLit(..) |
2357         hir::ExprPath(..) |
2358         hir::ExprIf(..) |
2359         hir::ExprWhile(..) |
2360         hir::ExprLoop(..) |
2361         hir::ExprMatch(..) |
2362         hir::ExprBlock(..) |
2363         hir::ExprStruct(..) => PREC_PAREN,
2364     }
2365 }
2366
2367 fn bin_op_to_assoc_op(op: hir::BinOp_) -> AssocOp {
2368     use hir::BinOp_::*;
2369     match op {
2370         BiAdd => AssocOp::Add,
2371         BiSub => AssocOp::Subtract,
2372         BiMul => AssocOp::Multiply,
2373         BiDiv => AssocOp::Divide,
2374         BiRem => AssocOp::Modulus,
2375
2376         BiAnd => AssocOp::LAnd,
2377         BiOr => AssocOp::LOr,
2378
2379         BiBitXor => AssocOp::BitXor,
2380         BiBitAnd => AssocOp::BitAnd,
2381         BiBitOr => AssocOp::BitOr,
2382         BiShl => AssocOp::ShiftLeft,
2383         BiShr => AssocOp::ShiftRight,
2384
2385         BiEq => AssocOp::Equal,
2386         BiLt => AssocOp::Less,
2387         BiLe => AssocOp::LessEqual,
2388         BiNe => AssocOp::NotEqual,
2389         BiGe => AssocOp::GreaterEqual,
2390         BiGt => AssocOp::Greater,
2391     }
2392 }
2393
2394 /// Expressions that syntactically contain an "exterior" struct literal i.e. not surrounded by any
2395 /// parens or other delimiters, e.g. `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
2396 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
2397 fn contains_exterior_struct_lit(value: &hir::Expr) -> bool {
2398     match value.node {
2399         hir::ExprStruct(..) => true,
2400
2401         hir::ExprAssign(ref lhs, ref rhs) |
2402         hir::ExprAssignOp(_, ref lhs, ref rhs) |
2403         hir::ExprBinary(_, ref lhs, ref rhs) => {
2404             // X { y: 1 } + X { y: 2 }
2405             contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
2406         }
2407         hir::ExprUnary(_, ref x) |
2408         hir::ExprCast(ref x, _) |
2409         hir::ExprType(ref x, _) |
2410         hir::ExprField(ref x, _) |
2411         hir::ExprTupField(ref x, _) |
2412         hir::ExprIndex(ref x, _) => {
2413             // &X { y: 1 }, X { y: 1 }.y
2414             contains_exterior_struct_lit(&x)
2415         }
2416
2417         hir::ExprMethodCall(.., ref exprs) => {
2418             // X { y: 1 }.bar(...)
2419             contains_exterior_struct_lit(&exprs[0])
2420         }
2421
2422         _ => false,
2423     }
2424 }