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