src/libsyntax/print/pprust.rs

   1 use crate::ast::{self, BlockCheckMode, PatKind, RangeEnd, RangeSyntax};
   2 use crate::ast::{SelfKind, GenericBound, TraitBoundModifier};
   3 use crate::ast::{Attribute, GenericArg, MacArgs};
   4 use crate::util::parser::{self, AssocOp, Fixity};
   5 use crate::util::comments;
   6 use crate::attr;
   7 use crate::source_map::{self, SourceMap, Spanned};
   8 use crate::token::{self, BinOpToken, DelimToken, Nonterminal, Token, TokenKind};
   9 use crate::print::pp::{self, Breaks};
  10 use crate::print::pp::Breaks::{Consistent, Inconsistent};
  11 use crate::ptr::P;
  12 use crate::util::classify;
  13 use crate::sess::ParseSess;
  14 use crate::symbol::{kw, sym};
  15 use crate::tokenstream::{self, TokenStream, TokenTree};
  16
  17 use syntax_pos::{self, BytePos};
  18 use syntax_pos::{FileName, Span};
  19
  20 use std::borrow::Cow;
  21
  22 #[cfg(test)]
  23 mod tests;
  24
  25 pub enum MacHeader<'a> {
  26     Path(&'a ast::Path),
  27     Keyword(&'static str),
  28 }
  29
  30 pub enum AnnNode<'a> {
  31     Ident(&'a ast::Ident),
  32     Name(&'a ast::Name),
  33     Block(&'a ast::Block),
  34     Item(&'a ast::Item),
  35     SubItem(ast::NodeId),
  36     Expr(&'a ast::Expr),
  37     Pat(&'a ast::Pat),
  38     Crate(&'a ast::Crate),
  39 }
  40
  41 pub trait PpAnn {
  42     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) { }
  43     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) { }
  44 }
  45
  46 #[derive(Copy, Clone)]
  47 pub struct NoAnn;
  48
  49 impl PpAnn for NoAnn {}
  50
  51 pub struct Comments<'a> {
  52     cm: &'a SourceMap,
  53     comments: Vec<comments::Comment>,
  54     current: usize,
  55 }
  56
  57 impl<'a> Comments<'a> {
  58     pub fn new(
  59         cm: &'a SourceMap,
  60         sess: &ParseSess,
  61         filename: FileName,
  62         input: String,
  63     ) -> Comments<'a> {
  64         let comments = comments::gather_comments(sess, filename, input);
  65         Comments {
  66             cm,
  67             comments,
  68             current: 0,
  69         }
  70     }
  71
  72     pub fn next(&self) -> Option<comments::Comment> {
  73         self.comments.get(self.current).cloned()
  74     }
  75
  76     pub fn trailing_comment(
  77         &mut self,
  78         span: syntax_pos::Span,
  79         next_pos: Option<BytePos>,
  80     ) -> Option<comments::Comment> {
  81         if let Some(cmnt) = self.next() {
  82             if cmnt.style != comments::Trailing { return None; }
  83             let span_line = self.cm.lookup_char_pos(span.hi());
  84             let comment_line = self.cm.lookup_char_pos(cmnt.pos);
  85             let next = next_pos.unwrap_or_else(|| cmnt.pos + BytePos(1));
  86             if span.hi() < cmnt.pos && cmnt.pos < next && span_line.line == comment_line.line {
  87                 return Some(cmnt);
  88             }
  89         }
  90
  91         None
  92     }
  93 }
  94
  95 pub struct State<'a> {
  96     pub s: pp::Printer,
  97     comments: Option<Comments<'a>>,
  98     ann: &'a (dyn PpAnn+'a),
  99     is_expanded: bool
 100 }
 101
 102 crate const INDENT_UNIT: usize = 4;
 103
 104 /// Requires you to pass an input filename and reader so that
 105 /// it can scan the input text for comments to copy forward.
 106 pub fn print_crate<'a>(cm: &'a SourceMap,
 107                        sess: &ParseSess,
 108                        krate: &ast::Crate,
 109                        filename: FileName,
 110                        input: String,
 111                        ann: &'a dyn PpAnn,
 112                        is_expanded: bool) -> String {
 113     let mut s = State {
 114         s: pp::mk_printer(),
 115         comments: Some(Comments::new(cm, sess, filename, input)),
 116         ann,
 117         is_expanded,
 118     };
 119
 120     if is_expanded && sess.injected_crate_name.try_get().is_some() {
 121         // We need to print `#![no_std]` (and its feature gate) so that
 122         // compiling pretty-printed source won't inject libstd again.
 123         // However, we don't want these attributes in the AST because
 124         // of the feature gate, so we fake them up here.
 125
 126         // `#![feature(prelude_import)]`
 127         let pi_nested = attr::mk_nested_word_item(ast::Ident::with_dummy_span(sym::prelude_import));
 128         let list = attr::mk_list_item(ast::Ident::with_dummy_span(sym::feature), vec![pi_nested]);
 129         let fake_attr = attr::mk_attr_inner(list);
 130         s.print_attribute(&fake_attr);
 131
 132         // Currently, in Rust 2018 we don't have `extern crate std;` at the crate
 133         // root, so this is not needed, and actually breaks things.
 134         if sess.edition == syntax_pos::edition::Edition::Edition2015 {
 135             // `#![no_std]`
 136             let no_std_meta = attr::mk_word_item(ast::Ident::with_dummy_span(sym::no_std));
 137             let fake_attr = attr::mk_attr_inner(no_std_meta);
 138             s.print_attribute(&fake_attr);
 139         }
 140     }
 141
 142     s.print_mod(&krate.module, &krate.attrs);
 143     s.print_remaining_comments();
 144     s.ann.post(&mut s, AnnNode::Crate(krate));
 145     s.s.eof()
 146 }
 147
 148 pub fn to_string<F>(f: F) -> String where
 149     F: FnOnce(&mut State<'_>),
 150 {
 151     let mut printer = State {
 152         s: pp::mk_printer(),
 153         comments: None,
 154         ann: &NoAnn,
 155         is_expanded: false
 156     };
 157     f(&mut printer);
 158     printer.s.eof()
 159 }
 160
 161 // This makes comma-separated lists look slightly nicer,
 162 // and also addresses a specific regression described in issue #63896.
 163 fn tt_prepend_space(tt: &TokenTree) -> bool {
 164     match tt {
 165         TokenTree::Token(token) => match token.kind {
 166             token::Comma => false,
 167             _ => true,
 168         }
 169         _ => true,
 170     }
 171 }
 172
 173 fn binop_to_string(op: BinOpToken) -> &'static str {
 174     match op {
 175         token::Plus     => "+",
 176         token::Minus    => "-",
 177         token::Star     => "*",
 178         token::Slash    => "/",
 179         token::Percent  => "%",
 180         token::Caret    => "^",
 181         token::And      => "&",
 182         token::Or       => "|",
 183         token::Shl      => "<<",
 184         token::Shr      => ">>",
 185     }
 186 }
 187
 188 pub fn literal_to_string(lit: token::Lit) -> String {
 189     let token::Lit { kind, symbol, suffix } = lit;
 190     let mut out = match kind {
 191         token::Byte          => format!("b'{}'", symbol),
 192         token::Char          => format!("'{}'", symbol),
 193         token::Str           => format!("\"{}\"", symbol),
 194         token::StrRaw(n)     => format!("r{delim}\"{string}\"{delim}",
 195                                         delim="#".repeat(n as usize),
 196                                         string=symbol),
 197         token::ByteStr       => format!("b\"{}\"", symbol),
 198         token::ByteStrRaw(n) => format!("br{delim}\"{string}\"{delim}",
 199                                         delim="#".repeat(n as usize),
 200                                         string=symbol),
 201         token::Integer       |
 202         token::Float         |
 203         token::Bool          |
 204         token::Err           => symbol.to_string(),
 205     };
 206
 207     if let Some(suffix) = suffix {
 208         out.push_str(&suffix.as_str())
 209     }
 210
 211     out
 212 }
 213
 214 /// Print an ident from AST, `$crate` is converted into its respective crate name.
 215 pub fn ast_ident_to_string(ident: ast::Ident, is_raw: bool) -> String {
 216     ident_to_string(ident.name, is_raw, Some(ident.span))
 217 }
 218
 219 // AST pretty-printer is used as a fallback for turning AST structures into token streams for
 220 // proc macros. Additionally, proc macros may stringify their input and expect it survive the
 221 // stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
 222 // So we need to somehow pretty-print `$crate` in a way preserving at least some of its
 223 // hygiene data, most importantly name of the crate it refers to.
 224 // As a result we print `$crate` as `crate` if it refers to the local crate
 225 // and as `::other_crate_name` if it refers to some other crate.
 226 // Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
 227 // but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
 228 // so we should not perform this lossy conversion if the top level call to the pretty-printer was
 229 // done for a token stream or a single token.
 230 fn ident_to_string(name: ast::Name, is_raw: bool, convert_dollar_crate: Option<Span>) -> String {
 231     if is_raw {
 232         format!("r#{}", name)
 233     } else {
 234         if name == kw::DollarCrate {
 235             if let Some(span) = convert_dollar_crate {
 236                 let converted = span.ctxt().dollar_crate_name();
 237                 return if converted.is_path_segment_keyword() {
 238                     converted.to_string()
 239                 } else {
 240                     format!("::{}", converted)
 241                 }
 242             }
 243         }
 244         name.to_string()
 245     }
 246 }
 247
 248 /// Print the token kind precisely, without converting `$crate` into its respective crate name.
 249 pub fn token_kind_to_string(tok: &TokenKind) -> String {
 250     token_kind_to_string_ext(tok, None)
 251 }
 252
 253 fn token_kind_to_string_ext(tok: &TokenKind, convert_dollar_crate: Option<Span>) -> String {
 254     match *tok {
 255         token::Eq                   => "=".to_string(),
 256         token::Lt                   => "<".to_string(),
 257         token::Le                   => "<=".to_string(),
 258         token::EqEq                 => "==".to_string(),
 259         token::Ne                   => "!=".to_string(),
 260         token::Ge                   => ">=".to_string(),
 261         token::Gt                   => ">".to_string(),
 262         token::Not                  => "!".to_string(),
 263         token::Tilde                => "~".to_string(),
 264         token::OrOr                 => "||".to_string(),
 265         token::AndAnd               => "&&".to_string(),
 266         token::BinOp(op)            => binop_to_string(op).to_string(),
 267         token::BinOpEq(op)          => format!("{}=", binop_to_string(op)),
 268
 269         /* Structural symbols */
 270         token::At                   => "@".to_string(),
 271         token::Dot                  => ".".to_string(),
 272         token::DotDot               => "..".to_string(),
 273         token::DotDotDot            => "...".to_string(),
 274         token::DotDotEq             => "..=".to_string(),
 275         token::Comma                => ",".to_string(),
 276         token::Semi                 => ";".to_string(),
 277         token::Colon                => ":".to_string(),
 278         token::ModSep               => "::".to_string(),
 279         token::RArrow               => "->".to_string(),
 280         token::LArrow               => "<-".to_string(),
 281         token::FatArrow             => "=>".to_string(),
 282         token::OpenDelim(token::Paren) => "(".to_string(),
 283         token::CloseDelim(token::Paren) => ")".to_string(),
 284         token::OpenDelim(token::Bracket) => "[".to_string(),
 285         token::CloseDelim(token::Bracket) => "]".to_string(),
 286         token::OpenDelim(token::Brace) => "{".to_string(),
 287         token::CloseDelim(token::Brace) => "}".to_string(),
 288         token::OpenDelim(token::NoDelim) |
 289         token::CloseDelim(token::NoDelim) => " ".to_string(),
 290         token::Pound                => "#".to_string(),
 291         token::Dollar               => "$".to_string(),
 292         token::Question             => "?".to_string(),
 293         token::SingleQuote          => "'".to_string(),
 294
 295         /* Literals */
 296         token::Literal(lit) => literal_to_string(lit),
 297
 298         /* Name components */
 299         token::Ident(s, is_raw)     => ident_to_string(s, is_raw, convert_dollar_crate),
 300         token::Lifetime(s)          => s.to_string(),
 301
 302         /* Other */
 303         token::DocComment(s)        => s.to_string(),
 304         token::Eof                  => "<eof>".to_string(),
 305         token::Whitespace           => " ".to_string(),
 306         token::Comment              => "/* */".to_string(),
 307         token::Shebang(s)           => format!("/* shebang: {}*/", s),
 308         token::Unknown(s)           => s.to_string(),
 309
 310         token::Interpolated(ref nt) => nonterminal_to_string(nt),
 311     }
 312 }
 313
 314 /// Print the token precisely, without converting `$crate` into its respective crate name.
 315 pub fn token_to_string(token: &Token) -> String {
 316     token_to_string_ext(token, false)
 317 }
 318
 319 fn token_to_string_ext(token: &Token, convert_dollar_crate: bool) -> String {
 320     let convert_dollar_crate = convert_dollar_crate.then_some(token.span);
 321     token_kind_to_string_ext(&token.kind, convert_dollar_crate)
 322 }
 323
 324 pub fn nonterminal_to_string(nt: &Nonterminal) -> String {
 325     match *nt {
 326         token::NtExpr(ref e)        => expr_to_string(e),
 327         token::NtMeta(ref e)        => attr_item_to_string(e),
 328         token::NtTy(ref e)          => ty_to_string(e),
 329         token::NtPath(ref e)        => path_to_string(e),
 330         token::NtItem(ref e)        => item_to_string(e),
 331         token::NtBlock(ref e)       => block_to_string(e),
 332         token::NtStmt(ref e)        => stmt_to_string(e),
 333         token::NtPat(ref e)         => pat_to_string(e),
 334         token::NtIdent(e, is_raw)   => ast_ident_to_string(e, is_raw),
 335         token::NtLifetime(e)        => e.to_string(),
 336         token::NtLiteral(ref e)     => expr_to_string(e),
 337         token::NtTT(ref tree)       => tt_to_string(tree.clone()),
 338         token::NtImplItem(ref e)    => impl_item_to_string(e),
 339         token::NtTraitItem(ref e)   => trait_item_to_string(e),
 340         token::NtVis(ref e)         => vis_to_string(e),
 341         token::NtForeignItem(ref e) => foreign_item_to_string(e),
 342     }
 343 }
 344
 345 pub fn ty_to_string(ty: &ast::Ty) -> String {
 346     to_string(|s| s.print_type(ty))
 347 }
 348
 349 pub fn bounds_to_string(bounds: &[ast::GenericBound]) -> String {
 350     to_string(|s| s.print_type_bounds("", bounds))
 351 }
 352
 353 pub fn pat_to_string(pat: &ast::Pat) -> String {
 354     to_string(|s| s.print_pat(pat))
 355 }
 356
 357 pub fn expr_to_string(e: &ast::Expr) -> String {
 358     to_string(|s| s.print_expr(e))
 359 }
 360
 361 pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
 362     to_string(|s| s.print_tt(tt, false))
 363 }
 364
 365 pub fn tts_to_string(tokens: TokenStream) -> String {
 366     to_string(|s| s.print_tts(tokens, false))
 367 }
 368
 369 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 370     to_string(|s| s.print_stmt(stmt))
 371 }
 372
 373 pub fn item_to_string(i: &ast::Item) -> String {
 374     to_string(|s| s.print_item(i))
 375 }
 376
 377 fn impl_item_to_string(i: &ast::ImplItem) -> String {
 378     to_string(|s| s.print_impl_item(i))
 379 }
 380
 381 fn trait_item_to_string(i: &ast::TraitItem) -> String {
 382     to_string(|s| s.print_trait_item(i))
 383 }
 384
 385 pub fn generic_params_to_string(generic_params: &[ast::GenericParam]) -> String {
 386     to_string(|s| s.print_generic_params(generic_params))
 387 }
 388
 389 pub fn path_to_string(p: &ast::Path) -> String {
 390     to_string(|s| s.print_path(p, false, 0))
 391 }
 392
 393 pub fn path_segment_to_string(p: &ast::PathSegment) -> String {
 394     to_string(|s| s.print_path_segment(p, false))
 395 }
 396
 397 pub fn vis_to_string(v: &ast::Visibility) -> String {
 398     to_string(|s| s.print_visibility(v))
 399 }
 400
 401 fn block_to_string(blk: &ast::Block) -> String {
 402     to_string(|s| {
 403         // Containing cbox, will be closed by `print_block` at `}`.
 404         s.cbox(INDENT_UNIT);
 405         // Head-ibox, will be closed by `print_block` after `{`.
 406         s.ibox(0);
 407         s.print_block(blk)
 408     })
 409 }
 410
 411 pub fn meta_list_item_to_string(li: &ast::NestedMetaItem) -> String {
 412     to_string(|s| s.print_meta_list_item(li))
 413 }
 414
 415 fn attr_item_to_string(ai: &ast::AttrItem) -> String {
 416     to_string(|s| s.print_attr_item(ai, ai.path.span))
 417 }
 418
 419 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 420     to_string(|s| s.print_attribute(attr))
 421 }
 422
 423 pub fn param_to_string(arg: &ast::Param) -> String {
 424     to_string(|s| s.print_param(arg, false))
 425 }
 426
 427 fn foreign_item_to_string(arg: &ast::ForeignItem) -> String {
 428     to_string(|s| s.print_foreign_item(arg))
 429 }
 430
 431 fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 432     format!("{}{}", to_string(|s| s.print_visibility(vis)), s)
 433 }
 434
 435 impl std::ops::Deref for State<'_> {
 436     type Target = pp::Printer;
 437     fn deref(&self) -> &Self::Target {
 438         &self.s
 439     }
 440 }
 441
 442 impl std::ops::DerefMut for State<'_> {
 443     fn deref_mut(&mut self) -> &mut Self::Target {
 444         &mut self.s
 445     }
 446 }
 447
 448 pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::DerefMut {
 449     fn comments(&mut self) -> &mut Option<Comments<'a>>;
 450     fn print_ident(&mut self, ident: ast::Ident);
 451     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool);
 452
 453     fn strsep<T, F>(&mut self, sep: &'static str, space_before: bool,
 454                     b: Breaks, elts: &[T], mut op: F)
 455         where F: FnMut(&mut Self, &T),
 456     {
 457         self.rbox(0, b);
 458         if let Some((first, rest)) = elts.split_first() {
 459             op(self, first);
 460             for elt in rest {
 461                 if space_before {
 462                     self.space();
 463                 }
 464                 self.word_space(sep);
 465                 op(self, elt);
 466             }
 467         }
 468         self.end();
 469     }
 470
 471     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], op: F)
 472         where F: FnMut(&mut Self, &T),
 473     {
 474         self.strsep(",", false, b, elts, op)
 475     }
 476
 477     fn maybe_print_comment(&mut self, pos: BytePos) {
 478         while let Some(ref cmnt) = self.next_comment() {
 479             if cmnt.pos < pos {
 480                 self.print_comment(cmnt);
 481             } else {
 482                 break
 483             }
 484         }
 485     }
 486
 487     fn print_comment(&mut self,
 488                      cmnt: &comments::Comment) {
 489         match cmnt.style {
 490             comments::Mixed => {
 491                 assert_eq!(cmnt.lines.len(), 1);
 492                 self.zerobreak();
 493                 self.word(cmnt.lines[0].clone());
 494                 self.zerobreak()
 495             }
 496             comments::Isolated => {
 497                 self.hardbreak_if_not_bol();
 498                 for line in &cmnt.lines {
 499                     // Don't print empty lines because they will end up as trailing
 500                     // whitespace.
 501                     if !line.is_empty() {
 502                         self.word(line.clone());
 503                     }
 504                     self.hardbreak();
 505                 }
 506             }
 507             comments::Trailing => {
 508                 if !self.is_beginning_of_line() {
 509                     self.word(" ");
 510                 }
 511                 if cmnt.lines.len() == 1 {
 512                     self.word(cmnt.lines[0].clone());
 513                     self.hardbreak()
 514                 } else {
 515                     self.ibox(0);
 516                     for line in &cmnt.lines {
 517                         if !line.is_empty() {
 518                             self.word(line.clone());
 519                         }
 520                         self.hardbreak();
 521                     }
 522                     self.end();
 523                 }
 524             }
 525             comments::BlankLine => {
 526                 // We need to do at least one, possibly two hardbreaks.
 527                 let twice = match self.last_token() {
 528                     pp::Token::String(s) => ";" == s,
 529                     pp::Token::Begin(_) => true,
 530                     pp::Token::End => true,
 531                     _ => false
 532                 };
 533                 if twice {
 534                     self.hardbreak();
 535                 }
 536                 self.hardbreak();
 537             }
 538         }
 539         if let Some(cm) = self.comments() {
 540             cm.current += 1;
 541         }
 542     }
 543
 544     fn next_comment(&mut self) -> Option<comments::Comment> {
 545         self.comments().as_mut().and_then(|c| c.next())
 546     }
 547
 548     fn print_literal(&mut self, lit: &ast::Lit) {
 549         self.maybe_print_comment(lit.span.lo());
 550         self.word(lit.token.to_string())
 551     }
 552
 553     fn print_string(&mut self, st: &str,
 554                     style: ast::StrStyle) {
 555         let st = match style {
 556             ast::StrStyle::Cooked => {
 557                 (format!("\"{}\"", st.escape_debug()))
 558             }
 559             ast::StrStyle::Raw(n) => {
 560                 (format!("r{delim}\"{string}\"{delim}",
 561                          delim="#".repeat(n as usize),
 562                          string=st))
 563             }
 564         };
 565         self.word(st)
 566     }
 567
 568     fn print_inner_attributes(&mut self,
 569                               attrs: &[ast::Attribute]) {
 570         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 571     }
 572
 573     fn print_inner_attributes_no_trailing_hardbreak(&mut self,
 574                                                    attrs: &[ast::Attribute])
 575                                                    {
 576         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 577     }
 578
 579     fn print_outer_attributes(&mut self,
 580                               attrs: &[ast::Attribute]) {
 581         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 582     }
 583
 584     fn print_inner_attributes_inline(&mut self,
 585                                      attrs: &[ast::Attribute]) {
 586         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 587     }
 588
 589     fn print_outer_attributes_inline(&mut self,
 590                                      attrs: &[ast::Attribute]) {
 591         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 592     }
 593
 594     fn print_either_attributes(&mut self,
 595                               attrs: &[ast::Attribute],
 596                               kind: ast::AttrStyle,
 597                               is_inline: bool,
 598                               trailing_hardbreak: bool) {
 599         let mut count = 0;
 600         for attr in attrs {
 601             if attr.style == kind {
 602                 self.print_attribute_inline(attr, is_inline);
 603                 if is_inline {
 604                     self.nbsp();
 605                 }
 606                 count += 1;
 607             }
 608         }
 609         if count > 0 && trailing_hardbreak && !is_inline {
 610             self.hardbreak_if_not_bol();
 611         }
 612     }
 613
 614     fn print_attribute(&mut self, attr: &ast::Attribute) {
 615         self.print_attribute_inline(attr, false)
 616     }
 617
 618     fn print_attribute_inline(&mut self, attr: &ast::Attribute,
 619                               is_inline: bool) {
 620         if !is_inline {
 621             self.hardbreak_if_not_bol();
 622         }
 623         self.maybe_print_comment(attr.span.lo());
 624         match attr.kind {
 625             ast::AttrKind::Normal(ref item) => {
 626                 match attr.style {
 627                     ast::AttrStyle::Inner => self.word("#!["),
 628                     ast::AttrStyle::Outer => self.word("#["),
 629                 }
 630                 self.print_attr_item(&item, attr.span);
 631                 self.word("]");
 632             }
 633             ast::AttrKind::DocComment(comment) => {
 634                 self.word(comment.to_string());
 635                 self.hardbreak()
 636             }
 637         }
 638     }
 639
 640     fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) {
 641         self.ibox(0);
 642         match &item.args {
 643             MacArgs::Delimited(_, delim, tokens) => self.print_mac_common(
 644                 Some(MacHeader::Path(&item.path)),
 645                 false,
 646                 None,
 647                 delim.to_token(),
 648                 tokens.clone(),
 649                 true,
 650                 span,
 651             ),
 652             MacArgs::Empty | MacArgs::Eq(..) => {
 653                 self.print_path(&item.path, false, 0);
 654                 if let MacArgs::Eq(_, tokens) = &item.args {
 655                     self.space();
 656                     self.word_space("=");
 657                     self.print_tts(tokens.clone(), true);
 658                 }
 659             }
 660         }
 661         self.end();
 662     }
 663
 664     fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) {
 665         match item {
 666             ast::NestedMetaItem::MetaItem(ref mi) => {
 667                 self.print_meta_item(mi)
 668             },
 669             ast::NestedMetaItem::Literal(ref lit) => {
 670                 self.print_literal(lit)
 671             }
 672         }
 673     }
 674
 675     fn print_meta_item(&mut self, item: &ast::MetaItem) {
 676         self.ibox(INDENT_UNIT);
 677         match item.kind {
 678             ast::MetaItemKind::Word => self.print_path(&item.path, false, 0),
 679             ast::MetaItemKind::NameValue(ref value) => {
 680                 self.print_path(&item.path, false, 0);
 681                 self.space();
 682                 self.word_space("=");
 683                 self.print_literal(value);
 684             }
 685             ast::MetaItemKind::List(ref items) => {
 686                 self.print_path(&item.path, false, 0);
 687                 self.popen();
 688                 self.commasep(Consistent,
 689                               &items[..],
 690                               |s, i| s.print_meta_list_item(i));
 691                 self.pclose();
 692             }
 693         }
 694         self.end();
 695     }
 696
 697     /// This doesn't deserve to be called "pretty" printing, but it should be
 698     /// meaning-preserving. A quick hack that might help would be to look at the
 699     /// spans embedded in the TTs to decide where to put spaces and newlines.
 700     /// But it'd be better to parse these according to the grammar of the
 701     /// appropriate macro, transcribe back into the grammar we just parsed from,
 702     /// and then pretty-print the resulting AST nodes (so, e.g., we print
 703     /// expression arguments as expressions). It can be done! I think.
 704     fn print_tt(&mut self, tt: tokenstream::TokenTree, convert_dollar_crate: bool) {
 705         match tt {
 706             TokenTree::Token(ref token) => {
 707                 self.word(token_to_string_ext(&token, convert_dollar_crate));
 708                 match token.kind {
 709                     token::DocComment(..) => {
 710                         self.hardbreak()
 711                     }
 712                     _ => {}
 713                 }
 714             }
 715             TokenTree::Delimited(dspan, delim, tts) => {
 716                 self.print_mac_common(
 717                     None, false, None, delim, tts, convert_dollar_crate, dspan.entire()
 718                 );
 719             }
 720         }
 721     }
 722
 723     fn print_tts(&mut self, tts: tokenstream::TokenStream, convert_dollar_crate: bool) {
 724         for (i, tt) in tts.into_trees().enumerate() {
 725             if i != 0 && tt_prepend_space(&tt) {
 726                 self.space();
 727             }
 728             self.print_tt(tt, convert_dollar_crate);
 729         }
 730     }
 731
 732     fn print_mac_common(
 733         &mut self,
 734         header: Option<MacHeader<'_>>,
 735         has_bang: bool,
 736         ident: Option<ast::Ident>,
 737         delim: DelimToken,
 738         tts: TokenStream,
 739         convert_dollar_crate: bool,
 740         span: Span,
 741     ) {
 742         if delim == DelimToken::Brace {
 743             self.cbox(INDENT_UNIT);
 744         }
 745         match header {
 746             Some(MacHeader::Path(path)) => self.print_path(path, false, 0),
 747             Some(MacHeader::Keyword(kw)) => self.word(kw),
 748             None => {}
 749         }
 750         if has_bang {
 751             self.word("!");
 752         }
 753         if let Some(ident) = ident {
 754             self.nbsp();
 755             self.print_ident(ident);
 756         }
 757         match delim {
 758             DelimToken::Brace => {
 759                 if header.is_some() || has_bang || ident.is_some() {
 760                     self.nbsp();
 761                 }
 762                 self.word("{");
 763                 if !tts.is_empty() {
 764                     self.space();
 765                 }
 766             }
 767             _ => self.word(token_kind_to_string(&token::OpenDelim(delim))),
 768         }
 769         self.ibox(0);
 770         self.print_tts(tts, convert_dollar_crate);
 771         self.end();
 772         match delim {
 773             DelimToken::Brace => self.bclose(span),
 774             _ => self.word(token_kind_to_string(&token::CloseDelim(delim))),
 775         }
 776     }
 777
 778     fn print_path(&mut self, path: &ast::Path, colons_before_params: bool, depth: usize) {
 779         self.maybe_print_comment(path.span.lo());
 780
 781         for (i, segment) in path.segments[..path.segments.len() - depth].iter().enumerate() {
 782             if i > 0 {
 783                 self.word("::")
 784             }
 785             self.print_path_segment(segment, colons_before_params);
 786         }
 787     }
 788
 789     fn print_path_segment(&mut self, segment: &ast::PathSegment, colons_before_params: bool) {
 790         if segment.ident.name != kw::PathRoot {
 791             self.print_ident(segment.ident);
 792             if let Some(ref args) = segment.args {
 793                 self.print_generic_args(args, colons_before_params);
 794             }
 795         }
 796     }
 797
 798     fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 799         let w = w.into();
 800         // Outer-box is consistent.
 801         self.cbox(INDENT_UNIT);
 802         // Head-box is inconsistent.
 803         self.ibox(w.len() + 1);
 804         // Keyword that starts the head.
 805         if !w.is_empty() {
 806             self.word_nbsp(w);
 807         }
 808     }
 809
 810     fn bopen(&mut self) {
 811         self.word("{");
 812         self.end(); // Close the head-box.
 813     }
 814
 815     fn bclose_maybe_open(&mut self, span: syntax_pos::Span, close_box: bool) {
 816         self.maybe_print_comment(span.hi());
 817         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
 818         self.word("}");
 819         if close_box {
 820             self.end(); // Close the outer-box.
 821         }
 822     }
 823
 824     fn bclose(&mut self, span: syntax_pos::Span) {
 825         self.bclose_maybe_open(span, true)
 826     }
 827
 828     fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
 829         if !self.is_beginning_of_line() {
 830             self.break_offset(n, off)
 831         } else {
 832             if off != 0 && self.last_token().is_hardbreak_tok() {
 833                 // We do something pretty sketchy here: tuck the nonzero
 834                 // offset-adjustment we were going to deposit along with the
 835                 // break into the previous hardbreak.
 836                 self.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 837             }
 838         }
 839     }
 840 }
 841
 842 impl<'a> PrintState<'a> for State<'a> {
 843     fn comments(&mut self) -> &mut Option<Comments<'a>> {
 844         &mut self.comments
 845     }
 846
 847     fn print_ident(&mut self, ident: ast::Ident) {
 848         self.s.word(ast_ident_to_string(ident, ident.is_raw_guess()));
 849         self.ann.post(self, AnnNode::Ident(&ident))
 850     }
 851
 852     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool) {
 853         if colons_before_params {
 854             self.s.word("::")
 855         }
 856
 857         match *args {
 858             ast::GenericArgs::AngleBracketed(ref data) => {
 859                 self.s.word("<");
 860
 861                 self.commasep(Inconsistent, &data.args, |s, generic_arg| {
 862                     s.print_generic_arg(generic_arg)
 863                 });
 864
 865                 let mut comma = data.args.len() != 0;
 866
 867                 for constraint in data.constraints.iter() {
 868                     if comma {
 869                         self.word_space(",")
 870                     }
 871                     self.print_ident(constraint.ident);
 872                     self.s.space();
 873                     match constraint.kind {
 874                         ast::AssocTyConstraintKind::Equality { ref ty } => {
 875                             self.word_space("=");
 876                             self.print_type(ty);
 877                         }
 878                         ast::AssocTyConstraintKind::Bound { ref bounds } => {
 879                             self.print_type_bounds(":", &*bounds);
 880                         }
 881                     }
 882                     comma = true;
 883                 }
 884
 885                 self.s.word(">")
 886             }
 887
 888             ast::GenericArgs::Parenthesized(ref data) => {
 889                 self.s.word("(");
 890                 self.commasep(
 891                     Inconsistent,
 892                     &data.inputs,
 893                     |s, ty| s.print_type(ty));
 894                 self.s.word(")");
 895
 896                 if let Some(ref ty) = data.output {
 897                     self.space_if_not_bol();
 898                     self.word_space("->");
 899                     self.print_type(ty);
 900                 }
 901             }
 902         }
 903     }
 904 }
 905
 906 impl<'a> State<'a> {
 907     // Synthesizes a comment that was not textually present in the original source
 908     // file.
 909     pub fn synth_comment(&mut self, text: String) {
 910         self.s.word("/*");
 911         self.s.space();
 912         self.s.word(text);
 913         self.s.space();
 914         self.s.word("*/")
 915     }
 916
 917     crate fn commasep_cmnt<T, F, G>(&mut self,
 918                                   b: Breaks,
 919                                   elts: &[T],
 920                                   mut op: F,
 921                                   mut get_span: G) where
 922         F: FnMut(&mut State<'_>, &T),
 923         G: FnMut(&T) -> syntax_pos::Span,
 924     {
 925         self.rbox(0, b);
 926         let len = elts.len();
 927         let mut i = 0;
 928         for elt in elts {
 929             self.maybe_print_comment(get_span(elt).hi());
 930             op(self, elt);
 931             i += 1;
 932             if i < len {
 933                 self.s.word(",");
 934                 self.maybe_print_trailing_comment(get_span(elt),
 935                                                   Some(get_span(&elts[i]).hi()));
 936                 self.space_if_not_bol();
 937             }
 938         }
 939         self.end();
 940     }
 941
 942     crate fn commasep_exprs(&mut self, b: Breaks,
 943                             exprs: &[P<ast::Expr>]) {
 944         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e), |e| e.span)
 945     }
 946
 947     pub fn print_mod(
 948         &mut self,
 949         _mod: &ast::Mod,
 950         attrs: &[ast::Attribute],
 951     ) {
 952         self.print_inner_attributes(attrs);
 953         for item in &_mod.items {
 954             self.print_item(item);
 955         }
 956     }
 957
 958     crate fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod,
 959                                attrs: &[ast::Attribute]) {
 960         self.print_inner_attributes(attrs);
 961         for item in &nmod.items {
 962             self.print_foreign_item(item);
 963         }
 964     }
 965
 966     pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
 967         if let Some(lt) = *lifetime {
 968             self.print_lifetime(lt);
 969             self.nbsp();
 970         }
 971     }
 972
 973     crate fn print_generic_arg(&mut self, generic_arg: &GenericArg) {
 974         match generic_arg {
 975             GenericArg::Lifetime(lt) => self.print_lifetime(*lt),
 976             GenericArg::Type(ty) => self.print_type(ty),
 977             GenericArg::Const(ct) => self.print_expr(&ct.value),
 978         }
 979     }
 980
 981     pub fn print_type(&mut self, ty: &ast::Ty) {
 982         self.maybe_print_comment(ty.span.lo());
 983         self.ibox(0);
 984         match ty.kind {
 985             ast::TyKind::Slice(ref ty) => {
 986                 self.s.word("[");
 987                 self.print_type(ty);
 988                 self.s.word("]");
 989             }
 990             ast::TyKind::Ptr(ref mt) => {
 991                 self.s.word("*");
 992                 self.print_mt(mt, true);
 993             }
 994             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 995                 self.s.word("&");
 996                 self.print_opt_lifetime(lifetime);
 997                 self.print_mt(mt, false);
 998             }
 999             ast::TyKind::Never => {
1000                 self.s.word("!");
1001             },
1002             ast::TyKind::Tup(ref elts) => {
1003                 self.popen();
1004                 self.commasep(Inconsistent, &elts[..],
1005                               |s, ty| s.print_type(ty));
1006                 if elts.len() == 1 {
1007                     self.s.word(",");
1008                 }
1009                 self.pclose();
1010             }
1011             ast::TyKind::Paren(ref typ) => {
1012                 self.popen();
1013                 self.print_type(typ);
1014                 self.pclose();
1015             }
1016             ast::TyKind::BareFn(ref f) => {
1017                 self.print_ty_fn(f.ext,
1018                                  f.unsafety,
1019                                  &f.decl,
1020                                  None,
1021                                  &f.generic_params);
1022             }
1023             ast::TyKind::Path(None, ref path) => {
1024                 self.print_path(path, false, 0);
1025             }
1026             ast::TyKind::Path(Some(ref qself), ref path) => {
1027                 self.print_qpath(path, qself, false)
1028             }
1029             ast::TyKind::TraitObject(ref bounds, syntax) => {
1030                 let prefix = if syntax == ast::TraitObjectSyntax::Dyn { "dyn" } else { "" };
1031                 self.print_type_bounds(prefix, &bounds[..]);
1032             }
1033             ast::TyKind::ImplTrait(_, ref bounds) => {
1034                 self.print_type_bounds("impl", &bounds[..]);
1035             }
1036             ast::TyKind::Array(ref ty, ref length) => {
1037                 self.s.word("[");
1038                 self.print_type(ty);
1039                 self.s.word("; ");
1040                 self.print_expr(&length.value);
1041                 self.s.word("]");
1042             }
1043             ast::TyKind::Typeof(ref e) => {
1044                 self.s.word("typeof(");
1045                 self.print_expr(&e.value);
1046                 self.s.word(")");
1047             }
1048             ast::TyKind::Infer => {
1049                 self.s.word("_");
1050             }
1051             ast::TyKind::Err => {
1052                 self.popen();
1053                 self.s.word("/*ERROR*/");
1054                 self.pclose();
1055             }
1056             ast::TyKind::ImplicitSelf => {
1057                 self.s.word("Self");
1058             }
1059             ast::TyKind::Mac(ref m) => {
1060                 self.print_mac(m);
1061             }
1062             ast::TyKind::CVarArgs => {
1063                 self.s.word("...");
1064             }
1065         }
1066         self.end();
1067     }
1068
1069     crate fn print_foreign_item(&mut self,
1070                               item: &ast::ForeignItem) {
1071         self.hardbreak_if_not_bol();
1072         self.maybe_print_comment(item.span.lo());
1073         self.print_outer_attributes(&item.attrs);
1074         match item.kind {
1075             ast::ForeignItemKind::Fn(ref decl, ref generics) => {
1076                 self.head("");
1077                 self.print_fn(decl, ast::FnHeader::default(),
1078                               Some(item.ident),
1079                               generics, &item.vis);
1080                 self.end(); // end head-ibox
1081                 self.s.word(";");
1082                 self.end(); // end the outer fn box
1083             }
1084             ast::ForeignItemKind::Static(ref t, m) => {
1085                 self.head(visibility_qualified(&item.vis, "static"));
1086                 if m == ast::Mutability::Mutable {
1087                     self.word_space("mut");
1088                 }
1089                 self.print_ident(item.ident);
1090                 self.word_space(":");
1091                 self.print_type(t);
1092                 self.s.word(";");
1093                 self.end(); // end the head-ibox
1094                 self.end(); // end the outer cbox
1095             }
1096             ast::ForeignItemKind::Ty => {
1097                 self.head(visibility_qualified(&item.vis, "type"));
1098                 self.print_ident(item.ident);
1099                 self.s.word(";");
1100                 self.end(); // end the head-ibox
1101                 self.end(); // end the outer cbox
1102             }
1103             ast::ForeignItemKind::Macro(ref m) => {
1104                 self.print_mac(m);
1105                 if m.args.need_semicolon() {
1106                     self.s.word(";");
1107                 }
1108             }
1109         }
1110     }
1111
1112     fn print_associated_const(&mut self,
1113                               ident: ast::Ident,
1114                               ty: &ast::Ty,
1115                               default: Option<&ast::Expr>,
1116                               vis: &ast::Visibility)
1117     {
1118         self.s.word(visibility_qualified(vis, ""));
1119         self.word_space("const");
1120         self.print_ident(ident);
1121         self.word_space(":");
1122         self.print_type(ty);
1123         if let Some(expr) = default {
1124             self.s.space();
1125             self.word_space("=");
1126             self.print_expr(expr);
1127         }
1128         self.s.word(";")
1129     }
1130
1131     fn print_associated_type(&mut self,
1132                              ident: ast::Ident,
1133                              bounds: Option<&ast::GenericBounds>,
1134                              ty: Option<&ast::Ty>)
1135                              {
1136         self.word_space("type");
1137         self.print_ident(ident);
1138         if let Some(bounds) = bounds {
1139             self.print_type_bounds(":", bounds);
1140         }
1141         if let Some(ty) = ty {
1142             self.s.space();
1143             self.word_space("=");
1144             self.print_type(ty);
1145         }
1146         self.s.word(";")
1147     }
1148
1149     /// Pretty-prints an item.
1150     crate fn print_item(&mut self, item: &ast::Item) {
1151         self.hardbreak_if_not_bol();
1152         self.maybe_print_comment(item.span.lo());
1153         self.print_outer_attributes(&item.attrs);
1154         self.ann.pre(self, AnnNode::Item(item));
1155         match item.kind {
1156             ast::ItemKind::ExternCrate(orig_name) => {
1157                 self.head(visibility_qualified(&item.vis, "extern crate"));
1158                 if let Some(orig_name) = orig_name {
1159                     self.print_name(orig_name);
1160                     self.s.space();
1161                     self.s.word("as");
1162                     self.s.space();
1163                 }
1164                 self.print_ident(item.ident);
1165                 self.s.word(";");
1166                 self.end(); // end inner head-block
1167                 self.end(); // end outer head-block
1168             }
1169             ast::ItemKind::Use(ref tree) => {
1170                 self.head(visibility_qualified(&item.vis, "use"));
1171                 self.print_use_tree(tree);
1172                 self.s.word(";");
1173                 self.end(); // end inner head-block
1174                 self.end(); // end outer head-block
1175             }
1176             ast::ItemKind::Static(ref ty, m, ref expr) => {
1177                 self.head(visibility_qualified(&item.vis, "static"));
1178                 if m == ast::Mutability::Mutable {
1179                     self.word_space("mut");
1180                 }
1181                 self.print_ident(item.ident);
1182                 self.word_space(":");
1183                 self.print_type(ty);
1184                 self.s.space();
1185                 self.end(); // end the head-ibox
1186
1187                 self.word_space("=");
1188                 self.print_expr(expr);
1189                 self.s.word(";");
1190                 self.end(); // end the outer cbox
1191             }
1192             ast::ItemKind::Const(ref ty, ref expr) => {
1193                 self.head(visibility_qualified(&item.vis, "const"));
1194                 self.print_ident(item.ident);
1195                 self.word_space(":");
1196                 self.print_type(ty);
1197                 self.s.space();
1198                 self.end(); // end the head-ibox
1199
1200                 self.word_space("=");
1201                 self.print_expr(expr);
1202                 self.s.word(";");
1203                 self.end(); // end the outer cbox
1204             }
1205             ast::ItemKind::Fn(ref sig, ref param_names, ref body) => {
1206                 self.head("");
1207                 self.print_fn(
1208                     &sig.decl,
1209                     sig.header,
1210                     Some(item.ident),
1211                     param_names,
1212                     &item.vis
1213                 );
1214                 self.s.word(" ");
1215                 self.print_block_with_attrs(body, &item.attrs);
1216             }
1217             ast::ItemKind::Mod(ref _mod) => {
1218                 self.head(visibility_qualified(&item.vis, "mod"));
1219                 self.print_ident(item.ident);
1220
1221                 if _mod.inline || self.is_expanded {
1222                     self.nbsp();
1223                     self.bopen();
1224                     self.print_mod(_mod, &item.attrs);
1225                     self.bclose(item.span);
1226                 } else {
1227                     self.s.word(";");
1228                     self.end(); // end inner head-block
1229                     self.end(); // end outer head-block
1230                 }
1231
1232             }
1233             ast::ItemKind::ForeignMod(ref nmod) => {
1234                 self.head("extern");
1235                 if let Some(abi) = nmod.abi {
1236                     self.print_literal(&abi.as_lit());
1237                     self.nbsp();
1238                 }
1239                 self.bopen();
1240                 self.print_foreign_mod(nmod, &item.attrs);
1241                 self.bclose(item.span);
1242             }
1243             ast::ItemKind::GlobalAsm(ref ga) => {
1244                 self.head(visibility_qualified(&item.vis, "global_asm!"));
1245                 self.s.word(ga.asm.to_string());
1246                 self.end();
1247             }
1248             ast::ItemKind::TyAlias(ref ty, ref generics) => {
1249                 self.head(visibility_qualified(&item.vis, "type"));
1250                 self.print_ident(item.ident);
1251                 self.print_generic_params(&generics.params);
1252                 self.end(); // end the inner ibox
1253
1254                 self.print_where_clause(&generics.where_clause);
1255                 self.s.space();
1256                 self.word_space("=");
1257                 self.print_type(ty);
1258                 self.s.word(";");
1259                 self.end(); // end the outer ibox
1260             }
1261             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1262                 self.print_enum_def(
1263                     enum_definition,
1264                     params,
1265                     item.ident,
1266                     item.span,
1267                     &item.vis
1268                 );
1269             }
1270             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1271                 self.head(visibility_qualified(&item.vis, "struct"));
1272                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1273             }
1274             ast::ItemKind::Union(ref struct_def, ref generics) => {
1275                 self.head(visibility_qualified(&item.vis, "union"));
1276                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1277             }
1278             ast::ItemKind::Impl(unsafety,
1279                           polarity,
1280                           defaultness,
1281                           ref generics,
1282                           ref opt_trait,
1283                           ref ty,
1284                           ref impl_items) => {
1285                 self.head("");
1286                 self.print_visibility(&item.vis);
1287                 self.print_defaultness(defaultness);
1288                 self.print_unsafety(unsafety);
1289                 self.word_nbsp("impl");
1290
1291                 if !generics.params.is_empty() {
1292                     self.print_generic_params(&generics.params);
1293                     self.s.space();
1294                 }
1295
1296                 if polarity == ast::ImplPolarity::Negative {
1297                     self.s.word("!");
1298                 }
1299
1300                 if let Some(ref t) = *opt_trait {
1301                     self.print_trait_ref(t);
1302                     self.s.space();
1303                     self.word_space("for");
1304                 }
1305
1306                 self.print_type(ty);
1307                 self.print_where_clause(&generics.where_clause);
1308
1309                 self.s.space();
1310                 self.bopen();
1311                 self.print_inner_attributes(&item.attrs);
1312                 for impl_item in impl_items {
1313                     self.print_impl_item(impl_item);
1314                 }
1315                 self.bclose(item.span);
1316             }
1317             ast::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref trait_items) => {
1318                 self.head("");
1319                 self.print_visibility(&item.vis);
1320                 self.print_unsafety(unsafety);
1321                 self.print_is_auto(is_auto);
1322                 self.word_nbsp("trait");
1323                 self.print_ident(item.ident);
1324                 self.print_generic_params(&generics.params);
1325                 let mut real_bounds = Vec::with_capacity(bounds.len());
1326                 for b in bounds.iter() {
1327                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1328                         self.s.space();
1329                         self.word_space("for ?");
1330                         self.print_trait_ref(&ptr.trait_ref);
1331                     } else {
1332                         real_bounds.push(b.clone());
1333                     }
1334                 }
1335                 self.print_type_bounds(":", &real_bounds[..]);
1336                 self.print_where_clause(&generics.where_clause);
1337                 self.s.word(" ");
1338                 self.bopen();
1339                 for trait_item in trait_items {
1340                     self.print_trait_item(trait_item);
1341                 }
1342                 self.bclose(item.span);
1343             }
1344             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
1345                 self.head("");
1346                 self.print_visibility(&item.vis);
1347                 self.word_nbsp("trait");
1348                 self.print_ident(item.ident);
1349                 self.print_generic_params(&generics.params);
1350                 let mut real_bounds = Vec::with_capacity(bounds.len());
1351                 // FIXME(durka) this seems to be some quite outdated syntax
1352                 for b in bounds.iter() {
1353                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1354                         self.s.space();
1355                         self.word_space("for ?");
1356                         self.print_trait_ref(&ptr.trait_ref);
1357                     } else {
1358                         real_bounds.push(b.clone());
1359                     }
1360                 }
1361                 self.nbsp();
1362                 self.print_type_bounds("=", &real_bounds[..]);
1363                 self.print_where_clause(&generics.where_clause);
1364                 self.s.word(";");
1365             }
1366             ast::ItemKind::Mac(ref mac) => {
1367                 self.print_mac(mac);
1368                 if mac.args.need_semicolon() {
1369                     self.s.word(";");
1370                 }
1371             }
1372             ast::ItemKind::MacroDef(ref macro_def) => {
1373                 let (kw, has_bang) = if macro_def.legacy {
1374                     ("macro_rules", true)
1375                 } else {
1376                     self.print_visibility(&item.vis);
1377                     ("macro", false)
1378                 };
1379                 self.print_mac_common(
1380                     Some(MacHeader::Keyword(kw)),
1381                     has_bang,
1382                     Some(item.ident),
1383                     macro_def.body.delim(),
1384                     macro_def.body.inner_tokens(),
1385                     true,
1386                     item.span,
1387                 );
1388             }
1389         }
1390         self.ann.post(self, AnnNode::Item(item))
1391     }
1392
1393     fn print_trait_ref(&mut self, t: &ast::TraitRef) {
1394         self.print_path(&t.path, false, 0)
1395     }
1396
1397     fn print_formal_generic_params(
1398         &mut self,
1399         generic_params: &[ast::GenericParam]
1400     ) {
1401         if !generic_params.is_empty() {
1402             self.s.word("for");
1403             self.print_generic_params(generic_params);
1404             self.nbsp();
1405         }
1406     }
1407
1408     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) {
1409         self.print_formal_generic_params(&t.bound_generic_params);
1410         self.print_trait_ref(&t.trait_ref)
1411     }
1412
1413     crate fn print_enum_def(&mut self, enum_definition: &ast::EnumDef,
1414                           generics: &ast::Generics, ident: ast::Ident,
1415                           span: syntax_pos::Span,
1416                           visibility: &ast::Visibility) {
1417         self.head(visibility_qualified(visibility, "enum"));
1418         self.print_ident(ident);
1419         self.print_generic_params(&generics.params);
1420         self.print_where_clause(&generics.where_clause);
1421         self.s.space();
1422         self.print_variants(&enum_definition.variants, span)
1423     }
1424
1425     crate fn print_variants(&mut self,
1426                           variants: &[ast::Variant],
1427                           span: syntax_pos::Span) {
1428         self.bopen();
1429         for v in variants {
1430             self.space_if_not_bol();
1431             self.maybe_print_comment(v.span.lo());
1432             self.print_outer_attributes(&v.attrs);
1433             self.ibox(INDENT_UNIT);
1434             self.print_variant(v);
1435             self.s.word(",");
1436             self.end();
1437             self.maybe_print_trailing_comment(v.span, None);
1438         }
1439         self.bclose(span)
1440     }
1441
1442     crate fn print_visibility(&mut self, vis: &ast::Visibility) {
1443         match vis.node {
1444             ast::VisibilityKind::Public => self.word_nbsp("pub"),
1445             ast::VisibilityKind::Crate(sugar) => match sugar {
1446                 ast::CrateSugar::PubCrate => self.word_nbsp("pub(crate)"),
1447                 ast::CrateSugar::JustCrate => self.word_nbsp("crate")
1448             }
1449             ast::VisibilityKind::Restricted { ref path, .. } => {
1450                 let path = to_string(|s| s.print_path(path, false, 0));
1451                 if path == "self" || path == "super" {
1452                     self.word_nbsp(format!("pub({})", path))
1453                 } else {
1454                     self.word_nbsp(format!("pub(in {})", path))
1455                 }
1456             }
1457             ast::VisibilityKind::Inherited => {}
1458         }
1459     }
1460
1461     crate fn print_defaultness(&mut self, defaultness: ast::Defaultness) {
1462         if let ast::Defaultness::Default = defaultness {
1463             self.word_nbsp("default");
1464         }
1465     }
1466
1467     crate fn print_struct(&mut self,
1468                         struct_def: &ast::VariantData,
1469                         generics: &ast::Generics,
1470                         ident: ast::Ident,
1471                         span: syntax_pos::Span,
1472                         print_finalizer: bool) {
1473         self.print_ident(ident);
1474         self.print_generic_params(&generics.params);
1475         match struct_def {
1476             ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
1477                 if let ast::VariantData::Tuple(..) = struct_def {
1478                     self.popen();
1479                     self.commasep(
1480                         Inconsistent, struct_def.fields(),
1481                         |s, field| {
1482                             s.maybe_print_comment(field.span.lo());
1483                             s.print_outer_attributes(&field.attrs);
1484                             s.print_visibility(&field.vis);
1485                             s.print_type(&field.ty)
1486                         }
1487                     );
1488                     self.pclose();
1489                 }
1490                 self.print_where_clause(&generics.where_clause);
1491                 if print_finalizer {
1492                     self.s.word(";");
1493                 }
1494                 self.end();
1495                 self.end(); // Close the outer-box.
1496             }
1497             ast::VariantData::Struct(..) => {
1498                 self.print_where_clause(&generics.where_clause);
1499                 self.nbsp();
1500                 self.bopen();
1501                 self.hardbreak_if_not_bol();
1502
1503                 for field in struct_def.fields() {
1504                     self.hardbreak_if_not_bol();
1505                     self.maybe_print_comment(field.span.lo());
1506                     self.print_outer_attributes(&field.attrs);
1507                     self.print_visibility(&field.vis);
1508                     self.print_ident(field.ident.unwrap());
1509                     self.word_nbsp(":");
1510                     self.print_type(&field.ty);
1511                     self.s.word(",");
1512                 }
1513
1514                 self.bclose(span)
1515             }
1516         }
1517     }
1518
1519     crate fn print_variant(&mut self, v: &ast::Variant) {
1520         self.head("");
1521         let generics = ast::Generics::default();
1522         self.print_struct(&v.data, &generics, v.ident, v.span, false);
1523         match v.disr_expr {
1524             Some(ref d) => {
1525                 self.s.space();
1526                 self.word_space("=");
1527                 self.print_expr(&d.value)
1528             }
1529             _ => {}
1530         }
1531     }
1532
1533     crate fn print_method_sig(&mut self,
1534                             ident: ast::Ident,
1535                             generics: &ast::Generics,
1536                             m: &ast::FnSig,
1537                             vis: &ast::Visibility)
1538                             {
1539         self.print_fn(&m.decl,
1540                       m.header,
1541                       Some(ident),
1542                       &generics,
1543                       vis)
1544     }
1545
1546     crate fn print_trait_item(&mut self, ti: &ast::TraitItem)
1547                             {
1548         self.ann.pre(self, AnnNode::SubItem(ti.id));
1549         self.hardbreak_if_not_bol();
1550         self.maybe_print_comment(ti.span.lo());
1551         self.print_outer_attributes(&ti.attrs);
1552         match ti.kind {
1553             ast::TraitItemKind::Const(ref ty, ref default) => {
1554                 self.print_associated_const(
1555                     ti.ident,
1556                     ty,
1557                     default.as_ref().map(|expr| &**expr),
1558                     &source_map::respan(ti.span.shrink_to_lo(), ast::VisibilityKind::Inherited),
1559                 );
1560             }
1561             ast::TraitItemKind::Method(ref sig, ref body) => {
1562                 if body.is_some() {
1563                     self.head("");
1564                 }
1565                 self.print_method_sig(
1566                     ti.ident,
1567                     &ti.generics,
1568                     sig,
1569                     &source_map::respan(ti.span.shrink_to_lo(), ast::VisibilityKind::Inherited),
1570                 );
1571                 if let Some(ref body) = *body {
1572                     self.nbsp();
1573                     self.print_block_with_attrs(body, &ti.attrs);
1574                 } else {
1575                     self.s.word(";");
1576                 }
1577             }
1578             ast::TraitItemKind::Type(ref bounds, ref default) => {
1579                 self.print_associated_type(ti.ident, Some(bounds),
1580                                            default.as_ref().map(|ty| &**ty));
1581             }
1582             ast::TraitItemKind::Macro(ref mac) => {
1583                 self.print_mac(mac);
1584                 if mac.args.need_semicolon() {
1585                     self.s.word(";");
1586                 }
1587             }
1588         }
1589         self.ann.post(self, AnnNode::SubItem(ti.id))
1590     }
1591
1592     crate fn print_impl_item(&mut self, ii: &ast::ImplItem) {
1593         self.ann.pre(self, AnnNode::SubItem(ii.id));
1594         self.hardbreak_if_not_bol();
1595         self.maybe_print_comment(ii.span.lo());
1596         self.print_outer_attributes(&ii.attrs);
1597         self.print_defaultness(ii.defaultness);
1598         match ii.kind {
1599             ast::ImplItemKind::Const(ref ty, ref expr) => {
1600                 self.print_associated_const(ii.ident, ty, Some(expr), &ii.vis);
1601             }
1602             ast::ImplItemKind::Method(ref sig, ref body) => {
1603                 self.head("");
1604                 self.print_method_sig(ii.ident, &ii.generics, sig, &ii.vis);
1605                 self.nbsp();
1606                 self.print_block_with_attrs(body, &ii.attrs);
1607             }
1608             ast::ImplItemKind::TyAlias(ref ty) => {
1609                 self.print_associated_type(ii.ident, None, Some(ty));
1610             }
1611             ast::ImplItemKind::Macro(ref mac) => {
1612                 self.print_mac(mac);
1613                 if mac.args.need_semicolon() {
1614                     self.s.word(";");
1615                 }
1616             }
1617         }
1618         self.ann.post(self, AnnNode::SubItem(ii.id))
1619     }
1620
1621     crate fn print_stmt(&mut self, st: &ast::Stmt) {
1622         self.maybe_print_comment(st.span.lo());
1623         match st.kind {
1624             ast::StmtKind::Local(ref loc) => {
1625                 self.print_outer_attributes(&loc.attrs);
1626                 self.space_if_not_bol();
1627                 self.ibox(INDENT_UNIT);
1628                 self.word_nbsp("let");
1629
1630                 self.ibox(INDENT_UNIT);
1631                 self.print_local_decl(loc);
1632                 self.end();
1633                 if let Some(ref init) = loc.init {
1634                     self.nbsp();
1635                     self.word_space("=");
1636                     self.print_expr(init);
1637                 }
1638                 self.s.word(";");
1639                 self.end();
1640             }
1641             ast::StmtKind::Item(ref item) => self.print_item(item),
1642             ast::StmtKind::Expr(ref expr) => {
1643                 self.space_if_not_bol();
1644                 self.print_expr_outer_attr_style(expr, false);
1645                 if classify::expr_requires_semi_to_be_stmt(expr) {
1646                     self.s.word(";");
1647                 }
1648             }
1649             ast::StmtKind::Semi(ref expr) => {
1650                 match expr.kind {
1651                     // Filter out empty `Tup` exprs created for the `redundant_semicolon`
1652                     // lint, as they shouldn't be visible and interact poorly
1653                     // with proc macros.
1654                     ast::ExprKind::Tup(ref exprs) if exprs.is_empty()
1655                       && expr.attrs.is_empty() => (),
1656                     _ => {
1657                         self.space_if_not_bol();
1658                         self.print_expr_outer_attr_style(expr, false);
1659                         self.s.word(";");
1660                     }
1661                 }
1662             }
1663             ast::StmtKind::Mac(ref mac) => {
1664                 let (ref mac, style, ref attrs) = **mac;
1665                 self.space_if_not_bol();
1666                 self.print_outer_attributes(attrs);
1667                 self.print_mac(mac);
1668                 if style == ast::MacStmtStyle::Semicolon {
1669                     self.s.word(";");
1670                 }
1671             }
1672         }
1673         self.maybe_print_trailing_comment(st.span, None)
1674     }
1675
1676     crate fn print_block(&mut self, blk: &ast::Block) {
1677         self.print_block_with_attrs(blk, &[])
1678     }
1679
1680     crate fn print_block_unclosed_indent(&mut self, blk: &ast::Block) {
1681         self.print_block_maybe_unclosed(blk, &[], false)
1682     }
1683
1684     crate fn print_block_with_attrs(&mut self,
1685                                   blk: &ast::Block,
1686                                   attrs: &[ast::Attribute]) {
1687         self.print_block_maybe_unclosed(blk, attrs, true)
1688     }
1689
1690     crate fn print_block_maybe_unclosed(&mut self,
1691                                       blk: &ast::Block,
1692                                       attrs: &[ast::Attribute],
1693                                       close_box: bool) {
1694         match blk.rules {
1695             BlockCheckMode::Unsafe(..) => self.word_space("unsafe"),
1696             BlockCheckMode::Default => ()
1697         }
1698         self.maybe_print_comment(blk.span.lo());
1699         self.ann.pre(self, AnnNode::Block(blk));
1700         self.bopen();
1701
1702         self.print_inner_attributes(attrs);
1703
1704         for (i, st) in blk.stmts.iter().enumerate() {
1705             match st.kind {
1706                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1707                     self.maybe_print_comment(st.span.lo());
1708                     self.space_if_not_bol();
1709                     self.print_expr_outer_attr_style(expr, false);
1710                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1711                 }
1712                 _ => self.print_stmt(st),
1713             }
1714         }
1715
1716         self.bclose_maybe_open(blk.span, close_box);
1717         self.ann.post(self, AnnNode::Block(blk))
1718     }
1719
1720     /// Print a `let pat = scrutinee` expression.
1721     crate fn print_let(&mut self, pat: &ast::Pat, scrutinee: &ast::Expr) {
1722         self.s.word("let ");
1723
1724         self.print_pat(pat);
1725         self.s.space();
1726
1727         self.word_space("=");
1728         self.print_expr_cond_paren(
1729             scrutinee,
1730             Self::cond_needs_par(scrutinee)
1731             || parser::needs_par_as_let_scrutinee(scrutinee.precedence().order())
1732         )
1733     }
1734
1735     fn print_else(&mut self, els: Option<&ast::Expr>) {
1736         if let Some(_else) = els {
1737             match _else.kind {
1738                 // Another `else if` block.
1739                 ast::ExprKind::If(ref i, ref then, ref e) => {
1740                     self.cbox(INDENT_UNIT - 1);
1741                     self.ibox(0);
1742                     self.s.word(" else if ");
1743                     self.print_expr_as_cond(i);
1744                     self.s.space();
1745                     self.print_block(then);
1746                     self.print_else(e.as_ref().map(|e| &**e))
1747                 }
1748                 // Final `else` block.
1749                 ast::ExprKind::Block(ref b, _) => {
1750                     self.cbox(INDENT_UNIT - 1);
1751                     self.ibox(0);
1752                     self.s.word(" else ");
1753                     self.print_block(b)
1754                 }
1755                 // Constraints would be great here!
1756                 _ => {
1757                     panic!("print_if saw if with weird alternative");
1758                 }
1759             }
1760         }
1761     }
1762
1763     crate fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block,
1764                     elseopt: Option<&ast::Expr>) {
1765         self.head("if");
1766
1767         self.print_expr_as_cond(test);
1768         self.s.space();
1769
1770         self.print_block(blk);
1771         self.print_else(elseopt)
1772     }
1773
1774     crate fn print_mac(&mut self, m: &ast::Mac) {
1775         self.print_mac_common(
1776             Some(MacHeader::Path(&m.path)),
1777             true,
1778             None,
1779             m.args.delim(),
1780             m.args.inner_tokens(),
1781             true,
1782             m.span(),
1783         );
1784     }
1785
1786     fn print_call_post(&mut self, args: &[P<ast::Expr>]) {
1787         self.popen();
1788         self.commasep_exprs(Inconsistent, args);
1789         self.pclose()
1790     }
1791
1792     crate fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8) {
1793         self.print_expr_cond_paren(expr, expr.precedence().order() < prec)
1794     }
1795
1796     /// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
1797     /// `if cond { ... }`.
1798     crate fn print_expr_as_cond(&mut self, expr: &ast::Expr) {
1799         self.print_expr_cond_paren(expr, Self::cond_needs_par(expr))
1800     }
1801
1802     /// Does `expr` need parenthesis when printed in a condition position?
1803     fn cond_needs_par(expr: &ast::Expr) -> bool {
1804         match expr.kind {
1805             // These cases need parens due to the parse error observed in #26461: `if return {}`
1806             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1807             ast::ExprKind::Closure(..) |
1808             ast::ExprKind::Ret(..) |
1809             ast::ExprKind::Break(..) => true,
1810
1811             _ => parser::contains_exterior_struct_lit(expr),
1812         }
1813     }
1814
1815     /// Prints `expr` or `(expr)` when `needs_par` holds.
1816     fn print_expr_cond_paren(&mut self, expr: &ast::Expr, needs_par: bool) {
1817         if needs_par {
1818             self.popen();
1819         }
1820         self.print_expr(expr);
1821         if needs_par {
1822             self.pclose();
1823         }
1824     }
1825
1826     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>],
1827                       attrs: &[Attribute]) {
1828         self.ibox(INDENT_UNIT);
1829         self.s.word("[");
1830         self.print_inner_attributes_inline(attrs);
1831         self.commasep_exprs(Inconsistent, &exprs[..]);
1832         self.s.word("]");
1833         self.end();
1834     }
1835
1836     fn print_expr_repeat(&mut self,
1837                          element: &ast::Expr,
1838                          count: &ast::AnonConst,
1839                          attrs: &[Attribute]) {
1840         self.ibox(INDENT_UNIT);
1841         self.s.word("[");
1842         self.print_inner_attributes_inline(attrs);
1843         self.print_expr(element);
1844         self.word_space(";");
1845         self.print_expr(&count.value);
1846         self.s.word("]");
1847         self.end();
1848     }
1849
1850     fn print_expr_struct(&mut self,
1851                          path: &ast::Path,
1852                          fields: &[ast::Field],
1853                          wth: &Option<P<ast::Expr>>,
1854                          attrs: &[Attribute]) {
1855         self.print_path(path, true, 0);
1856         self.s.word("{");
1857         self.print_inner_attributes_inline(attrs);
1858         self.commasep_cmnt(
1859             Consistent,
1860             &fields[..],
1861             |s, field| {
1862                 s.ibox(INDENT_UNIT);
1863                 if !field.is_shorthand {
1864                     s.print_ident(field.ident);
1865                     s.word_space(":");
1866                 }
1867                 s.print_expr(&field.expr);
1868                 s.end();
1869             },
1870             |f| f.span);
1871         match *wth {
1872             Some(ref expr) => {
1873                 self.ibox(INDENT_UNIT);
1874                 if !fields.is_empty() {
1875                     self.s.word(",");
1876                     self.s.space();
1877                 }
1878                 self.s.word("..");
1879                 self.print_expr(expr);
1880                 self.end();
1881             }
1882             _ => if !fields.is_empty() {
1883                 self.s.word(",")
1884             }
1885         }
1886         self.s.word("}");
1887     }
1888
1889     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>],
1890                       attrs: &[Attribute]) {
1891         self.popen();
1892         self.print_inner_attributes_inline(attrs);
1893         self.commasep_exprs(Inconsistent, &exprs[..]);
1894         if exprs.len() == 1 {
1895             self.s.word(",");
1896         }
1897         self.pclose()
1898     }
1899
1900     fn print_expr_call(&mut self,
1901                        func: &ast::Expr,
1902                        args: &[P<ast::Expr>]) {
1903         let prec =
1904             match func.kind {
1905                 ast::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1906                 _ => parser::PREC_POSTFIX,
1907             };
1908
1909         self.print_expr_maybe_paren(func, prec);
1910         self.print_call_post(args)
1911     }
1912
1913     fn print_expr_method_call(&mut self,
1914                               segment: &ast::PathSegment,
1915                               args: &[P<ast::Expr>]) {
1916         let base_args = &args[1..];
1917         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1918         self.s.word(".");
1919         self.print_ident(segment.ident);
1920         if let Some(ref args) = segment.args {
1921             self.print_generic_args(args, true);
1922         }
1923         self.print_call_post(base_args)
1924     }
1925
1926     fn print_expr_binary(&mut self,
1927                          op: ast::BinOp,
1928                          lhs: &ast::Expr,
1929                          rhs: &ast::Expr) {
1930         let assoc_op = AssocOp::from_ast_binop(op.node);
1931         let prec = assoc_op.precedence() as i8;
1932         let fixity = assoc_op.fixity();
1933
1934         let (left_prec, right_prec) = match fixity {
1935             Fixity::Left => (prec, prec + 1),
1936             Fixity::Right => (prec + 1, prec),
1937             Fixity::None => (prec + 1, prec + 1),
1938         };
1939
1940         let left_prec = match (&lhs.kind, op.node) {
1941             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1942             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1943             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1944             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Lt) |
1945             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Shl) => parser::PREC_FORCE_PAREN,
1946             // We are given `(let _ = a) OP b`.
1947             //
1948             // - When `OP <= LAnd` we should print `let _ = a OP b` to avoid redundant parens
1949             //   as the parser will interpret this as `(let _ = a) OP b`.
1950             //
1951             // - Otherwise, e.g. when we have `(let a = b) < c` in AST,
1952             //   parens are required since the parser would interpret `let a = b < c` as
1953             //   `let a = (b < c)`. To achieve this, we force parens.
1954             (&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
1955                 parser::PREC_FORCE_PAREN
1956             }
1957             _ => left_prec,
1958         };
1959
1960         self.print_expr_maybe_paren(lhs, left_prec);
1961         self.s.space();
1962         self.word_space(op.node.to_string());
1963         self.print_expr_maybe_paren(rhs, right_prec)
1964     }
1965
1966     fn print_expr_unary(&mut self,
1967                         op: ast::UnOp,
1968                         expr: &ast::Expr) {
1969         self.s.word(ast::UnOp::to_string(op));
1970         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1971     }
1972
1973     fn print_expr_addr_of(&mut self,
1974                           kind: ast::BorrowKind,
1975                           mutability: ast::Mutability,
1976                           expr: &ast::Expr) {
1977         self.s.word("&");
1978         match kind {
1979             ast::BorrowKind::Ref => self.print_mutability(mutability, false),
1980             ast::BorrowKind::Raw => {
1981                 self.word_nbsp("raw");
1982                 self.print_mutability(mutability, true);
1983             }
1984         }
1985         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1986     }
1987
1988     pub fn print_expr(&mut self, expr: &ast::Expr) {
1989         self.print_expr_outer_attr_style(expr, true)
1990     }
1991
1992     fn print_expr_outer_attr_style(&mut self,
1993                                   expr: &ast::Expr,
1994                                   is_inline: bool) {
1995         self.maybe_print_comment(expr.span.lo());
1996
1997         let attrs = &expr.attrs;
1998         if is_inline {
1999             self.print_outer_attributes_inline(attrs);
2000         } else {
2001             self.print_outer_attributes(attrs);
2002         }
2003
2004         self.ibox(INDENT_UNIT);
2005         self.ann.pre(self, AnnNode::Expr(expr));
2006         match expr.kind {
2007             ast::ExprKind::Box(ref expr) => {
2008                 self.word_space("box");
2009                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
2010             }
2011             ast::ExprKind::Array(ref exprs) => {
2012                 self.print_expr_vec(&exprs[..], attrs);
2013             }
2014             ast::ExprKind::Repeat(ref element, ref count) => {
2015                 self.print_expr_repeat(element, count, attrs);
2016             }
2017             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
2018                 self.print_expr_struct(path, &fields[..], wth, attrs);
2019             }
2020             ast::ExprKind::Tup(ref exprs) => {
2021                 self.print_expr_tup(&exprs[..], attrs);
2022             }
2023             ast::ExprKind::Call(ref func, ref args) => {
2024                 self.print_expr_call(func, &args[..]);
2025             }
2026             ast::ExprKind::MethodCall(ref segment, ref args) => {
2027                 self.print_expr_method_call(segment, &args[..]);
2028             }
2029             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
2030                 self.print_expr_binary(op, lhs, rhs);
2031             }
2032             ast::ExprKind::Unary(op, ref expr) => {
2033                 self.print_expr_unary(op, expr);
2034             }
2035             ast::ExprKind::AddrOf(k, m, ref expr) => {
2036                 self.print_expr_addr_of(k, m, expr);
2037             }
2038             ast::ExprKind::Lit(ref lit) => {
2039                 self.print_literal(lit);
2040             }
2041             ast::ExprKind::Cast(ref expr, ref ty) => {
2042                 let prec = AssocOp::As.precedence() as i8;
2043                 self.print_expr_maybe_paren(expr, prec);
2044                 self.s.space();
2045                 self.word_space("as");
2046                 self.print_type(ty);
2047             }
2048             ast::ExprKind::Type(ref expr, ref ty) => {
2049                 let prec = AssocOp::Colon.precedence() as i8;
2050                 self.print_expr_maybe_paren(expr, prec);
2051                 self.word_space(":");
2052                 self.print_type(ty);
2053             }
2054             ast::ExprKind::Let(ref pat, ref scrutinee) => {
2055                 self.print_let(pat, scrutinee);
2056             }
2057             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
2058                 self.print_if(test, blk, elseopt.as_ref().map(|e| &**e));
2059             }
2060             ast::ExprKind::While(ref test, ref blk, opt_label) => {
2061                 if let Some(label) = opt_label {
2062                     self.print_ident(label.ident);
2063                     self.word_space(":");
2064                 }
2065                 self.head("while");
2066                 self.print_expr_as_cond(test);
2067                 self.s.space();
2068                 self.print_block_with_attrs(blk, attrs);
2069             }
2070             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_label) => {
2071                 if let Some(label) = opt_label {
2072                     self.print_ident(label.ident);
2073                     self.word_space(":");
2074                 }
2075                 self.head("for");
2076                 self.print_pat(pat);
2077                 self.s.space();
2078                 self.word_space("in");
2079                 self.print_expr_as_cond(iter);
2080                 self.s.space();
2081                 self.print_block_with_attrs(blk, attrs);
2082             }
2083             ast::ExprKind::Loop(ref blk, opt_label) => {
2084                 if let Some(label) = opt_label {
2085                     self.print_ident(label.ident);
2086                     self.word_space(":");
2087                 }
2088                 self.head("loop");
2089                 self.s.space();
2090                 self.print_block_with_attrs(blk, attrs);
2091             }
2092             ast::ExprKind::Match(ref expr, ref arms) => {
2093                 self.cbox(INDENT_UNIT);
2094                 self.ibox(INDENT_UNIT);
2095                 self.word_nbsp("match");
2096                 self.print_expr_as_cond(expr);
2097                 self.s.space();
2098                 self.bopen();
2099                 self.print_inner_attributes_no_trailing_hardbreak(attrs);
2100                 for arm in arms {
2101                     self.print_arm(arm);
2102                 }
2103                 self.bclose(expr.span);
2104             }
2105             ast::ExprKind::Closure(
2106                 capture_clause, asyncness, movability, ref decl, ref body, _) => {
2107                 self.print_movability(movability);
2108                 self.print_asyncness(asyncness);
2109                 self.print_capture_clause(capture_clause);
2110
2111                 self.print_fn_block_params(decl);
2112                 self.s.space();
2113                 self.print_expr(body);
2114                 self.end(); // need to close a box
2115
2116                 // a box will be closed by print_expr, but we didn't want an overall
2117                 // wrapper so we closed the corresponding opening. so create an
2118                 // empty box to satisfy the close.
2119                 self.ibox(0);
2120             }
2121             ast::ExprKind::Block(ref blk, opt_label) => {
2122                 if let Some(label) = opt_label {
2123                     self.print_ident(label.ident);
2124                     self.word_space(":");
2125                 }
2126                 // containing cbox, will be closed by print-block at }
2127                 self.cbox(INDENT_UNIT);
2128                 // head-box, will be closed by print-block after {
2129                 self.ibox(0);
2130                 self.print_block_with_attrs(blk, attrs);
2131             }
2132             ast::ExprKind::Async(capture_clause, _, ref blk) => {
2133                 self.word_nbsp("async");
2134                 self.print_capture_clause(capture_clause);
2135                 self.s.space();
2136                 // cbox/ibox in analogy to the `ExprKind::Block` arm above
2137                 self.cbox(INDENT_UNIT);
2138                 self.ibox(0);
2139                 self.print_block_with_attrs(blk, attrs);
2140             }
2141             ast::ExprKind::Await(ref expr) => {
2142                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2143                 self.s.word(".await");
2144             }
2145             ast::ExprKind::Assign(ref lhs, ref rhs) => {
2146                 let prec = AssocOp::Assign.precedence() as i8;
2147                 self.print_expr_maybe_paren(lhs, prec + 1);
2148                 self.s.space();
2149                 self.word_space("=");
2150                 self.print_expr_maybe_paren(rhs, prec);
2151             }
2152             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2153                 let prec = AssocOp::Assign.precedence() as i8;
2154                 self.print_expr_maybe_paren(lhs, prec + 1);
2155                 self.s.space();
2156                 self.s.word(op.node.to_string());
2157                 self.word_space("=");
2158                 self.print_expr_maybe_paren(rhs, prec);
2159             }
2160             ast::ExprKind::Field(ref expr, ident) => {
2161                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2162                 self.s.word(".");
2163                 self.print_ident(ident);
2164             }
2165             ast::ExprKind::Index(ref expr, ref index) => {
2166                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2167                 self.s.word("[");
2168                 self.print_expr(index);
2169                 self.s.word("]");
2170             }
2171             ast::ExprKind::Range(ref start, ref end, limits) => {
2172                 // Special case for `Range`.  `AssocOp` claims that `Range` has higher precedence
2173                 // than `Assign`, but `x .. x = x` gives a parse error instead of `x .. (x = x)`.
2174                 // Here we use a fake precedence value so that any child with lower precedence than
2175                 // a "normal" binop gets parenthesized.  (`LOr` is the lowest-precedence binop.)
2176                 let fake_prec = AssocOp::LOr.precedence() as i8;
2177                 if let Some(ref e) = *start {
2178                     self.print_expr_maybe_paren(e, fake_prec);
2179                 }
2180                 if limits == ast::RangeLimits::HalfOpen {
2181                     self.s.word("..");
2182                 } else {
2183                     self.s.word("..=");
2184                 }
2185                 if let Some(ref e) = *end {
2186                     self.print_expr_maybe_paren(e, fake_prec);
2187                 }
2188             }
2189             ast::ExprKind::Path(None, ref path) => {
2190                 self.print_path(path, true, 0)
2191             }
2192             ast::ExprKind::Path(Some(ref qself), ref path) => {
2193                 self.print_qpath(path, qself, true)
2194             }
2195             ast::ExprKind::Break(opt_label, ref opt_expr) => {
2196                 self.s.word("break");
2197                 self.s.space();
2198                 if let Some(label) = opt_label {
2199                     self.print_ident(label.ident);
2200                     self.s.space();
2201                 }
2202                 if let Some(ref expr) = *opt_expr {
2203                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2204                     self.s.space();
2205                 }
2206             }
2207             ast::ExprKind::Continue(opt_label) => {
2208                 self.s.word("continue");
2209                 self.s.space();
2210                 if let Some(label) = opt_label {
2211                     self.print_ident(label.ident);
2212                     self.s.space()
2213                 }
2214             }
2215             ast::ExprKind::Ret(ref result) => {
2216                 self.s.word("return");
2217                 if let Some(ref expr) = *result {
2218                     self.s.word(" ");
2219                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2220                 }
2221             }
2222             ast::ExprKind::InlineAsm(ref a) => {
2223                 self.s.word("asm!");
2224                 self.popen();
2225                 self.print_string(&a.asm.as_str(), a.asm_str_style);
2226                 self.word_space(":");
2227
2228                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2229                     let constraint = out.constraint.as_str();
2230                     let mut ch = constraint.chars();
2231                     match ch.next() {
2232                         Some('=') if out.is_rw => {
2233                             s.print_string(&format!("+{}", ch.as_str()),
2234                                            ast::StrStyle::Cooked)
2235                         }
2236                         _ => s.print_string(&constraint, ast::StrStyle::Cooked)
2237                     }
2238                     s.popen();
2239                     s.print_expr(&out.expr);
2240                     s.pclose();
2241                 });
2242                 self.s.space();
2243                 self.word_space(":");
2244
2245                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2246                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
2247                     s.popen();
2248                     s.print_expr(o);
2249                     s.pclose();
2250                 });
2251                 self.s.space();
2252                 self.word_space(":");
2253
2254                 self.commasep(Inconsistent, &a.clobbers,
2255                                    |s, co| {
2256                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
2257                 });
2258
2259                 let mut options = vec![];
2260                 if a.volatile {
2261                     options.push("volatile");
2262                 }
2263                 if a.alignstack {
2264                     options.push("alignstack");
2265                 }
2266                 if a.dialect == ast::AsmDialect::Intel {
2267                     options.push("intel");
2268                 }
2269
2270                 if !options.is_empty() {
2271                     self.s.space();
2272                     self.word_space(":");
2273                     self.commasep(Inconsistent, &options,
2274                                   |s, &co| {
2275                                       s.print_string(co, ast::StrStyle::Cooked);
2276                                   });
2277                 }
2278
2279                 self.pclose();
2280             }
2281             ast::ExprKind::Mac(ref m) => self.print_mac(m),
2282             ast::ExprKind::Paren(ref e) => {
2283                 self.popen();
2284                 self.print_inner_attributes_inline(attrs);
2285                 self.print_expr(e);
2286                 self.pclose();
2287             },
2288             ast::ExprKind::Yield(ref e) => {
2289                 self.s.word("yield");
2290                 match *e {
2291                     Some(ref expr) => {
2292                         self.s.space();
2293                         self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2294                     }
2295                     _ => ()
2296                 }
2297             }
2298             ast::ExprKind::Try(ref e) => {
2299                 self.print_expr_maybe_paren(e, parser::PREC_POSTFIX);
2300                 self.s.word("?")
2301             }
2302             ast::ExprKind::TryBlock(ref blk) => {
2303                 self.head("try");
2304                 self.s.space();
2305                 self.print_block_with_attrs(blk, attrs)
2306             }
2307             ast::ExprKind::Err => {
2308                 self.popen();
2309                 self.s.word("/*ERROR*/");
2310                 self.pclose()
2311             }
2312         }
2313         self.ann.post(self, AnnNode::Expr(expr));
2314         self.end();
2315     }
2316
2317     crate fn print_local_decl(&mut self, loc: &ast::Local) {
2318         self.print_pat(&loc.pat);
2319         if let Some(ref ty) = loc.ty {
2320             self.word_space(":");
2321             self.print_type(ty);
2322         }
2323     }
2324
2325     pub fn print_usize(&mut self, i: usize) {
2326         self.s.word(i.to_string())
2327     }
2328
2329     crate fn print_name(&mut self, name: ast::Name) {
2330         self.s.word(name.to_string());
2331         self.ann.post(self, AnnNode::Name(&name))
2332     }
2333
2334     fn print_qpath(&mut self,
2335                    path: &ast::Path,
2336                    qself: &ast::QSelf,
2337                    colons_before_params: bool)
2338     {
2339         self.s.word("<");
2340         self.print_type(&qself.ty);
2341         if qself.position > 0 {
2342             self.s.space();
2343             self.word_space("as");
2344             let depth = path.segments.len() - qself.position;
2345             self.print_path(path, false, depth);
2346         }
2347         self.s.word(">");
2348         self.s.word("::");
2349         let item_segment = path.segments.last().unwrap();
2350         self.print_ident(item_segment.ident);
2351         match item_segment.args {
2352             Some(ref args) => self.print_generic_args(args, colons_before_params),
2353             None => {},
2354         }
2355     }
2356
2357     crate fn print_pat(&mut self, pat: &ast::Pat) {
2358         self.maybe_print_comment(pat.span.lo());
2359         self.ann.pre(self, AnnNode::Pat(pat));
2360         /* Pat isn't normalized, but the beauty of it
2361          is that it doesn't matter */
2362         match pat.kind {
2363             PatKind::Wild => self.s.word("_"),
2364             PatKind::Ident(binding_mode, ident, ref sub) => {
2365                 match binding_mode {
2366                     ast::BindingMode::ByRef(mutbl) => {
2367                         self.word_nbsp("ref");
2368                         self.print_mutability(mutbl, false);
2369                     }
2370                     ast::BindingMode::ByValue(ast::Mutability::Immutable) => {}
2371                     ast::BindingMode::ByValue(ast::Mutability::Mutable) => {
2372                         self.word_nbsp("mut");
2373                     }
2374                 }
2375                 self.print_ident(ident);
2376                 if let Some(ref p) = *sub {
2377                     self.s.space();
2378                     self.s.word_space("@");
2379                     self.print_pat(p);
2380                 }
2381             }
2382             PatKind::TupleStruct(ref path, ref elts) => {
2383                 self.print_path(path, true, 0);
2384                 self.popen();
2385                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2386                 self.pclose();
2387             }
2388             PatKind::Or(ref pats) => {
2389                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(p));
2390             }
2391             PatKind::Path(None, ref path) => {
2392                 self.print_path(path, true, 0);
2393             }
2394             PatKind::Path(Some(ref qself), ref path) => {
2395                 self.print_qpath(path, qself, false);
2396             }
2397             PatKind::Struct(ref path, ref fields, etc) => {
2398                 self.print_path(path, true, 0);
2399                 self.nbsp();
2400                 self.word_space("{");
2401                 self.commasep_cmnt(
2402                     Consistent, &fields[..],
2403                     |s, f| {
2404                         s.cbox(INDENT_UNIT);
2405                         if !f.is_shorthand {
2406                             s.print_ident(f.ident);
2407                             s.word_nbsp(":");
2408                         }
2409                         s.print_pat(&f.pat);
2410                         s.end();
2411                     },
2412                     |f| f.pat.span);
2413                 if etc {
2414                     if !fields.is_empty() { self.word_space(","); }
2415                     self.s.word("..");
2416                 }
2417                 self.s.space();
2418                 self.s.word("}");
2419             }
2420             PatKind::Tuple(ref elts) => {
2421                 self.popen();
2422                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2423                 if elts.len() == 1 {
2424                     self.s.word(",");
2425                 }
2426                 self.pclose();
2427             }
2428             PatKind::Box(ref inner) => {
2429                 self.s.word("box ");
2430                 self.print_pat(inner);
2431             }
2432             PatKind::Ref(ref inner, mutbl) => {
2433                 self.s.word("&");
2434                 if mutbl == ast::Mutability::Mutable {
2435                     self.s.word("mut ");
2436                 }
2437                 self.print_pat(inner);
2438             }
2439             PatKind::Lit(ref e) => self.print_expr(&**e),
2440             PatKind::Range(ref begin, ref end, Spanned { node: ref end_kind, .. }) => {
2441                 self.print_expr(begin);
2442                 self.s.space();
2443                 match *end_kind {
2444                     RangeEnd::Included(RangeSyntax::DotDotDot) => self.s.word("..."),
2445                     RangeEnd::Included(RangeSyntax::DotDotEq) => self.s.word("..="),
2446                     RangeEnd::Excluded => self.s.word(".."),
2447                 }
2448                 self.print_expr(end);
2449             }
2450             PatKind::Slice(ref elts) => {
2451                 self.s.word("[");
2452                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2453                 self.s.word("]");
2454             }
2455             PatKind::Rest => self.s.word(".."),
2456             PatKind::Paren(ref inner) => {
2457                 self.popen();
2458                 self.print_pat(inner);
2459                 self.pclose();
2460             }
2461             PatKind::Mac(ref m) => self.print_mac(m),
2462         }
2463         self.ann.post(self, AnnNode::Pat(pat))
2464     }
2465
2466     fn print_arm(&mut self, arm: &ast::Arm) {
2467         // Note, I have no idea why this check is necessary, but here it is.
2468         if arm.attrs.is_empty() {
2469             self.s.space();
2470         }
2471         self.cbox(INDENT_UNIT);
2472         self.ibox(0);
2473         self.maybe_print_comment(arm.pat.span.lo());
2474         self.print_outer_attributes(&arm.attrs);
2475         self.print_pat(&arm.pat);
2476         self.s.space();
2477         if let Some(ref e) = arm.guard {
2478             self.word_space("if");
2479             self.print_expr(e);
2480             self.s.space();
2481         }
2482         self.word_space("=>");
2483
2484         match arm.body.kind {
2485             ast::ExprKind::Block(ref blk, opt_label) => {
2486                 if let Some(label) = opt_label {
2487                     self.print_ident(label.ident);
2488                     self.word_space(":");
2489                 }
2490
2491                 // The block will close the pattern's ibox.
2492                 self.print_block_unclosed_indent(blk);
2493
2494                 // If it is a user-provided unsafe block, print a comma after it.
2495                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2496                     self.s.word(",");
2497                 }
2498             }
2499             _ => {
2500                 self.end(); // Close the ibox for the pattern.
2501                 self.print_expr(&arm.body);
2502                 self.s.word(",");
2503             }
2504         }
2505         self.end(); // Close enclosing cbox.
2506     }
2507
2508     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) {
2509         match explicit_self.node {
2510             SelfKind::Value(m) => {
2511                 self.print_mutability(m, false);
2512                 self.s.word("self")
2513             }
2514             SelfKind::Region(ref lt, m) => {
2515                 self.s.word("&");
2516                 self.print_opt_lifetime(lt);
2517                 self.print_mutability(m, false);
2518                 self.s.word("self")
2519             }
2520             SelfKind::Explicit(ref typ, m) => {
2521                 self.print_mutability(m, false);
2522                 self.s.word("self");
2523                 self.word_space(":");
2524                 self.print_type(typ)
2525             }
2526         }
2527     }
2528
2529     crate fn print_fn(&mut self,
2530                     decl: &ast::FnDecl,
2531                     header: ast::FnHeader,
2532                     name: Option<ast::Ident>,
2533                     generics: &ast::Generics,
2534                     vis: &ast::Visibility) {
2535         self.print_fn_header_info(header, vis);
2536
2537         if let Some(name) = name {
2538             self.nbsp();
2539             self.print_ident(name);
2540         }
2541         self.print_generic_params(&generics.params);
2542         self.print_fn_params_and_ret(decl);
2543         self.print_where_clause(&generics.where_clause)
2544     }
2545
2546     crate fn print_fn_params_and_ret(&mut self, decl: &ast::FnDecl) {
2547         self.popen();
2548         self.commasep(Inconsistent, &decl.inputs, |s, param| s.print_param(param, false));
2549         self.pclose();
2550
2551         self.print_fn_output(decl)
2552     }
2553
2554     crate fn print_fn_block_params(&mut self, decl: &ast::FnDecl) {
2555         self.s.word("|");
2556         self.commasep(Inconsistent, &decl.inputs, |s, param| s.print_param(param, true));
2557         self.s.word("|");
2558
2559         if let ast::FunctionRetTy::Default(..) = decl.output {
2560             return;
2561         }
2562
2563         self.space_if_not_bol();
2564         self.word_space("->");
2565         match decl.output {
2566             ast::FunctionRetTy::Ty(ref ty) => {
2567                 self.print_type(ty);
2568                 self.maybe_print_comment(ty.span.lo())
2569             }
2570             ast::FunctionRetTy::Default(..) => unreachable!(),
2571         }
2572     }
2573
2574     crate fn print_movability(&mut self, movability: ast::Movability) {
2575         match movability {
2576             ast::Movability::Static => self.word_space("static"),
2577             ast::Movability::Movable => {},
2578         }
2579     }
2580
2581     crate fn print_asyncness(&mut self, asyncness: ast::IsAsync) {
2582         if asyncness.is_async() {
2583             self.word_nbsp("async");
2584         }
2585     }
2586
2587     crate fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy) {
2588         match capture_clause {
2589             ast::CaptureBy::Value => self.word_space("move"),
2590             ast::CaptureBy::Ref => {},
2591         }
2592     }
2593
2594     pub fn print_type_bounds(&mut self, prefix: &'static str, bounds: &[ast::GenericBound]) {
2595         if !bounds.is_empty() {
2596             self.s.word(prefix);
2597             let mut first = true;
2598             for bound in bounds {
2599                 if !(first && prefix.is_empty()) {
2600                     self.nbsp();
2601                 }
2602                 if first {
2603                     first = false;
2604                 } else {
2605                     self.word_space("+");
2606                 }
2607
2608                 match bound {
2609                     GenericBound::Trait(tref, modifier) => {
2610                         if modifier == &TraitBoundModifier::Maybe {
2611                             self.s.word("?");
2612                         }
2613                         self.print_poly_trait_ref(tref);
2614                     }
2615                     GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2616                 }
2617             }
2618         }
2619     }
2620
2621     crate fn print_lifetime(&mut self, lifetime: ast::Lifetime) {
2622         self.print_name(lifetime.ident.name)
2623     }
2624
2625     crate fn print_lifetime_bounds(
2626         &mut self, lifetime: ast::Lifetime, bounds: &ast::GenericBounds) {
2627         self.print_lifetime(lifetime);
2628         if !bounds.is_empty() {
2629             self.s.word(": ");
2630             for (i, bound) in bounds.iter().enumerate() {
2631                 if i != 0 {
2632                     self.s.word(" + ");
2633                 }
2634                 match bound {
2635                     ast::GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2636                     _ => panic!(),
2637                 }
2638             }
2639         }
2640     }
2641
2642     crate fn print_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
2643         if generic_params.is_empty() {
2644             return;
2645         }
2646
2647         self.s.word("<");
2648
2649         self.commasep(Inconsistent, &generic_params, |s, param| {
2650             s.print_outer_attributes_inline(&param.attrs);
2651
2652             match param.kind {
2653                 ast::GenericParamKind::Lifetime => {
2654                     let lt = ast::Lifetime { id: param.id, ident: param.ident };
2655                     s.print_lifetime_bounds(lt, &param.bounds)
2656                 }
2657                 ast::GenericParamKind::Type { ref default } => {
2658                     s.print_ident(param.ident);
2659                     s.print_type_bounds(":", &param.bounds);
2660                     if let Some(ref default) = default {
2661                         s.s.space();
2662                         s.word_space("=");
2663                         s.print_type(default)
2664                     }
2665                 }
2666                 ast::GenericParamKind::Const { ref ty } => {
2667                     s.word_space("const");
2668                     s.print_ident(param.ident);
2669                     s.s.space();
2670                     s.word_space(":");
2671                     s.print_type(ty);
2672                     s.print_type_bounds(":", &param.bounds)
2673                 }
2674             }
2675         });
2676
2677         self.s.word(">");
2678     }
2679
2680     crate fn print_where_clause(&mut self, where_clause: &ast::WhereClause) {
2681         if where_clause.predicates.is_empty() {
2682             return;
2683         }
2684
2685         self.s.space();
2686         self.word_space("where");
2687
2688         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2689             if i != 0 {
2690                 self.word_space(",");
2691             }
2692
2693             match *predicate {
2694                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
2695                     ref bound_generic_params,
2696                     ref bounded_ty,
2697                     ref bounds,
2698                     ..
2699                 }) => {
2700                     self.print_formal_generic_params(bound_generic_params);
2701                     self.print_type(bounded_ty);
2702                     self.print_type_bounds(":", bounds);
2703                 }
2704                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
2705                                                                                ref bounds,
2706                                                                                ..}) => {
2707                     self.print_lifetime_bounds(*lifetime, bounds);
2708                 }
2709                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{ref lhs_ty,
2710                                                                        ref rhs_ty,
2711                                                                        ..}) => {
2712                     self.print_type(lhs_ty);
2713                     self.s.space();
2714                     self.word_space("=");
2715                     self.print_type(rhs_ty);
2716                 }
2717             }
2718         }
2719     }
2720
2721     crate fn print_use_tree(&mut self, tree: &ast::UseTree) {
2722         match tree.kind {
2723             ast::UseTreeKind::Simple(rename, ..) => {
2724                 self.print_path(&tree.prefix, false, 0);
2725                 if let Some(rename) = rename {
2726                     self.s.space();
2727                     self.word_space("as");
2728                     self.print_ident(rename);
2729                 }
2730             }
2731             ast::UseTreeKind::Glob => {
2732                 if !tree.prefix.segments.is_empty() {
2733                     self.print_path(&tree.prefix, false, 0);
2734                     self.s.word("::");
2735                 }
2736                 self.s.word("*");
2737             }
2738             ast::UseTreeKind::Nested(ref items) => {
2739                 if tree.prefix.segments.is_empty() {
2740                     self.s.word("{");
2741                 } else {
2742                     self.print_path(&tree.prefix, false, 0);
2743                     self.s.word("::{");
2744                 }
2745                 self.commasep(Inconsistent, &items[..], |this, &(ref tree, _)| {
2746                     this.print_use_tree(tree)
2747                 });
2748                 self.s.word("}");
2749             }
2750         }
2751     }
2752
2753     pub fn print_mutability(&mut self, mutbl: ast::Mutability, print_const: bool) {
2754         match mutbl {
2755             ast::Mutability::Mutable => self.word_nbsp("mut"),
2756             ast::Mutability::Immutable => if print_const { self.word_nbsp("const"); },
2757         }
2758     }
2759
2760     crate fn print_mt(&mut self, mt: &ast::MutTy, print_const: bool) {
2761         self.print_mutability(mt.mutbl, print_const);
2762         self.print_type(&mt.ty)
2763     }
2764
2765     crate fn print_param(&mut self, input: &ast::Param, is_closure: bool) {
2766         self.ibox(INDENT_UNIT);
2767
2768         self.print_outer_attributes_inline(&input.attrs);
2769
2770         match input.ty.kind {
2771             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat),
2772             _ => {
2773                 if let Some(eself) = input.to_self() {
2774                     self.print_explicit_self(&eself);
2775                 } else {
2776                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.kind {
2777                         ident.name == kw::Invalid
2778                     } else {
2779                         false
2780                     };
2781                     if !invalid {
2782                         self.print_pat(&input.pat);
2783                         self.s.word(":");
2784                         self.s.space();
2785                     }
2786                     self.print_type(&input.ty);
2787                 }
2788             }
2789         }
2790         self.end();
2791     }
2792
2793     crate fn print_fn_output(&mut self, decl: &ast::FnDecl) {
2794         if let ast::FunctionRetTy::Default(..) = decl.output {
2795             return;
2796         }
2797
2798         self.space_if_not_bol();
2799         self.ibox(INDENT_UNIT);
2800         self.word_space("->");
2801         match decl.output {
2802             ast::FunctionRetTy::Default(..) => unreachable!(),
2803             ast::FunctionRetTy::Ty(ref ty) =>
2804                 self.print_type(ty),
2805         }
2806         self.end();
2807
2808         match decl.output {
2809             ast::FunctionRetTy::Ty(ref output) => self.maybe_print_comment(output.span.lo()),
2810             _ => {}
2811         }
2812     }
2813
2814     crate fn print_ty_fn(&mut self,
2815                        ext: ast::Extern,
2816                        unsafety: ast::Unsafety,
2817                        decl: &ast::FnDecl,
2818                        name: Option<ast::Ident>,
2819                        generic_params: &[ast::GenericParam])
2820                        {
2821         self.ibox(INDENT_UNIT);
2822         if !generic_params.is_empty() {
2823             self.s.word("for");
2824             self.print_generic_params(generic_params);
2825         }
2826         let generics = ast::Generics {
2827             params: Vec::new(),
2828             where_clause: ast::WhereClause {
2829                 predicates: Vec::new(),
2830                 span: syntax_pos::DUMMY_SP,
2831             },
2832             span: syntax_pos::DUMMY_SP,
2833         };
2834         self.print_fn(decl,
2835                       ast::FnHeader { unsafety, ext, ..ast::FnHeader::default() },
2836                       name,
2837                       &generics,
2838                       &source_map::dummy_spanned(ast::VisibilityKind::Inherited));
2839         self.end();
2840     }
2841
2842     crate fn maybe_print_trailing_comment(&mut self, span: syntax_pos::Span,
2843                                         next_pos: Option<BytePos>)
2844     {
2845         if let Some(cmnts) = self.comments() {
2846             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2847                 self.print_comment(&cmnt);
2848             }
2849         }
2850     }
2851
2852     crate fn print_remaining_comments(&mut self) {
2853         // If there aren't any remaining comments, then we need to manually
2854         // make sure there is a line break at the end.
2855         if self.next_comment().is_none() {
2856             self.s.hardbreak();
2857         }
2858         while let Some(ref cmnt) = self.next_comment() {
2859             self.print_comment(cmnt);
2860         }
2861     }
2862
2863     crate fn print_fn_header_info(&mut self,
2864                                 header: ast::FnHeader,
2865                                 vis: &ast::Visibility) {
2866         self.s.word(visibility_qualified(vis, ""));
2867
2868         match header.constness.node {
2869             ast::Constness::NotConst => {}
2870             ast::Constness::Const => self.word_nbsp("const")
2871         }
2872
2873         self.print_asyncness(header.asyncness.node);
2874         self.print_unsafety(header.unsafety);
2875
2876         match header.ext {
2877             ast::Extern::None => {}
2878             ast::Extern::Implicit => {
2879                 self.word_nbsp("extern");
2880             }
2881             ast::Extern::Explicit(abi) => {
2882                 self.word_nbsp("extern");
2883                 self.print_literal(&abi.as_lit());
2884                 self.nbsp();
2885             }
2886         }
2887
2888         self.s.word("fn")
2889     }
2890
2891     crate fn print_unsafety(&mut self, s: ast::Unsafety) {
2892         match s {
2893             ast::Unsafety::Normal => {},
2894             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2895         }
2896     }
2897
2898     crate fn print_is_auto(&mut self, s: ast::IsAuto) {
2899         match s {
2900             ast::IsAuto::Yes => self.word_nbsp("auto"),
2901             ast::IsAuto::No => {}
2902         }
2903     }
2904 }