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