src/libsyntax/ext/quote.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use ast::{self, Arg, Arm, Block, Expr, Item, Pat, Stmt, Ty};
  12 use syntax_pos::Span;
  13 use ext::base::ExtCtxt;
  14 use ext::base;
  15 use ext::build::AstBuilder;
  16 use parse::parser::{Parser, PathStyle};
  17 use parse::token;
  18 use ptr::P;
  19 use tokenstream::{TokenStream, TokenTree};
  20
  21
  22 /// Quasiquoting works via token trees.
  23 ///
  24 /// This is registered as a set of expression syntax extension called quote!
  25 /// that lifts its argument token-tree to an AST representing the
  26 /// construction of the same token tree, with token::SubstNt interpreted
  27 /// as antiquotes (splices).
  28
  29 pub mod rt {
  30     use ast;
  31     use codemap::Spanned;
  32     use ext::base::ExtCtxt;
  33     use parse::{self, token, classify};
  34     use ptr::P;
  35     use std::rc::Rc;
  36     use symbol::Symbol;
  37
  38     use tokenstream::{self, TokenTree, TokenStream};
  39
  40     pub use parse::new_parser_from_tts;
  41     pub use syntax_pos::{BytePos, Span, DUMMY_SP};
  42     pub use codemap::{dummy_spanned};
  43
  44     pub trait ToTokens {
  45         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree>;
  46     }
  47
  48     impl ToTokens for TokenTree {
  49         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  50             vec![self.clone()]
  51         }
  52     }
  53
  54     impl<T: ToTokens> ToTokens for Vec<T> {
  55         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
  56             self.iter().flat_map(|t| t.to_tokens(cx)).collect()
  57         }
  58     }
  59
  60     impl<T: ToTokens> ToTokens for Spanned<T> {
  61         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
  62             // FIXME: use the span?
  63             self.node.to_tokens(cx)
  64         }
  65     }
  66
  67     impl<T: ToTokens> ToTokens for Option<T> {
  68         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
  69             match *self {
  70                 Some(ref t) => t.to_tokens(cx),
  71                 None => Vec::new(),
  72             }
  73         }
  74     }
  75
  76     impl ToTokens for ast::Ident {
  77         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  78             vec![TokenTree::Token(DUMMY_SP, token::Ident(*self))]
  79         }
  80     }
  81
  82     impl ToTokens for ast::Path {
  83         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  84             let nt = token::NtPath(self.clone());
  85             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
  86         }
  87     }
  88
  89     impl ToTokens for ast::Ty {
  90         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  91             let nt = token::NtTy(P(self.clone()));
  92             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
  93         }
  94     }
  95
  96     impl ToTokens for ast::Block {
  97         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  98             let nt = token::NtBlock(P(self.clone()));
  99             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 100         }
 101     }
 102
 103     impl ToTokens for ast::Generics {
 104         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 105             let nt = token::NtGenerics(self.clone());
 106             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
 107         }
 108     }
 109
 110     impl ToTokens for ast::WhereClause {
 111         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 112             let nt = token::NtWhereClause(self.clone());
 113             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
 114         }
 115     }
 116
 117     impl ToTokens for P<ast::Item> {
 118         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 119             let nt = token::NtItem(self.clone());
 120             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 121         }
 122     }
 123
 124     impl ToTokens for ast::ImplItem {
 125         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 126             let nt = token::NtImplItem(self.clone());
 127             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 128         }
 129     }
 130
 131     impl ToTokens for P<ast::ImplItem> {
 132         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 133             let nt = token::NtImplItem((**self).clone());
 134             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 135         }
 136     }
 137
 138     impl ToTokens for ast::TraitItem {
 139         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 140             let nt = token::NtTraitItem(self.clone());
 141             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 142         }
 143     }
 144
 145     impl ToTokens for ast::Stmt {
 146         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 147             let nt = token::NtStmt(self.clone());
 148             let mut tts = vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))];
 149
 150             // Some statements require a trailing semicolon.
 151             if classify::stmt_ends_with_semi(&self.node) {
 152                 tts.push(TokenTree::Token(self.span, token::Semi));
 153             }
 154
 155             tts
 156         }
 157     }
 158
 159     impl ToTokens for P<ast::Expr> {
 160         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 161             let nt = token::NtExpr(self.clone());
 162             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 163         }
 164     }
 165
 166     impl ToTokens for P<ast::Pat> {
 167         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 168             let nt = token::NtPat(self.clone());
 169             vec![TokenTree::Token(self.span, token::Interpolated(Rc::new(nt)))]
 170         }
 171     }
 172
 173     impl ToTokens for ast::Arm {
 174         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 175             let nt = token::NtArm(self.clone());
 176             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
 177         }
 178     }
 179
 180     impl ToTokens for ast::Arg {
 181         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 182             let nt = token::NtArg(self.clone());
 183             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
 184         }
 185     }
 186
 187     impl ToTokens for P<ast::Block> {
 188         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 189             let nt = token::NtBlock(self.clone());
 190             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
 191         }
 192     }
 193
 194     macro_rules! impl_to_tokens_slice {
 195         ($t: ty, $sep: expr) => {
 196             impl ToTokens for [$t] {
 197                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 198                     let mut v = vec![];
 199                     for (i, x) in self.iter().enumerate() {
 200                         if i > 0 {
 201                             v.extend_from_slice(&$sep);
 202                         }
 203                         v.extend(x.to_tokens(cx));
 204                     }
 205                     v
 206                 }
 207             }
 208         };
 209     }
 210
 211     impl_to_tokens_slice! { ast::Ty, [TokenTree::Token(DUMMY_SP, token::Comma)] }
 212     impl_to_tokens_slice! { P<ast::Item>, [] }
 213     impl_to_tokens_slice! { ast::Arg, [TokenTree::Token(DUMMY_SP, token::Comma)] }
 214
 215     impl ToTokens for ast::MetaItem {
 216         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 217             let nt = token::NtMeta(self.clone());
 218             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(Rc::new(nt)))]
 219         }
 220     }
 221
 222     impl ToTokens for ast::Attribute {
 223         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 224             let mut r = vec![];
 225             // FIXME: The spans could be better
 226             r.push(TokenTree::Token(self.span, token::Pound));
 227             if self.style == ast::AttrStyle::Inner {
 228                 r.push(TokenTree::Token(self.span, token::Not));
 229             }
 230             r.push(TokenTree::Delimited(self.span, tokenstream::Delimited {
 231                 delim: token::Bracket,
 232                 tts: self.value.to_tokens(cx).into_iter().collect::<TokenStream>().into(),
 233             }));
 234             r
 235         }
 236     }
 237
 238     impl ToTokens for str {
 239         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 240             let lit = ast::LitKind::Str(Symbol::intern(self), ast::StrStyle::Cooked);
 241             dummy_spanned(lit).to_tokens(cx)
 242         }
 243     }
 244
 245     impl ToTokens for () {
 246         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 247             vec![TokenTree::Delimited(DUMMY_SP, tokenstream::Delimited {
 248                 delim: token::Paren,
 249                 tts: TokenStream::empty().into(),
 250             })]
 251         }
 252     }
 253
 254     impl ToTokens for ast::Lit {
 255         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 256             // FIXME: This is wrong
 257             P(ast::Expr {
 258                 id: ast::DUMMY_NODE_ID,
 259                 node: ast::ExprKind::Lit(P(self.clone())),
 260                 span: DUMMY_SP,
 261                 attrs: ast::ThinVec::new(),
 262             }).to_tokens(cx)
 263         }
 264     }
 265
 266     impl ToTokens for bool {
 267         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 268             dummy_spanned(ast::LitKind::Bool(*self)).to_tokens(cx)
 269         }
 270     }
 271
 272     impl ToTokens for char {
 273         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 274             dummy_spanned(ast::LitKind::Char(*self)).to_tokens(cx)
 275         }
 276     }
 277
 278     macro_rules! impl_to_tokens_int {
 279         (signed, $t:ty, $tag:expr) => (
 280             impl ToTokens for $t {
 281                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 282                     let val = if *self < 0 {
 283                         -self
 284                     } else {
 285                         *self
 286                     };
 287                     let lit = ast::LitKind::Int(val as u128, ast::LitIntType::Signed($tag));
 288                     let lit = P(ast::Expr {
 289                         id: ast::DUMMY_NODE_ID,
 290                         node: ast::ExprKind::Lit(P(dummy_spanned(lit))),
 291                         span: DUMMY_SP,
 292                         attrs: ast::ThinVec::new(),
 293                     });
 294                     if *self >= 0 {
 295                         return lit.to_tokens(cx);
 296                     }
 297                     P(ast::Expr {
 298                         id: ast::DUMMY_NODE_ID,
 299                         node: ast::ExprKind::Unary(ast::UnOp::Neg, lit),
 300                         span: DUMMY_SP,
 301                         attrs: ast::ThinVec::new(),
 302                     }).to_tokens(cx)
 303                 }
 304             }
 305         );
 306         (unsigned, $t:ty, $tag:expr) => (
 307             impl ToTokens for $t {
 308                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 309                     let lit = ast::LitKind::Int(*self as u128, ast::LitIntType::Unsigned($tag));
 310                     dummy_spanned(lit).to_tokens(cx)
 311                 }
 312             }
 313         );
 314     }
 315
 316     impl_to_tokens_int! { signed, isize, ast::IntTy::Is }
 317     impl_to_tokens_int! { signed, i8,  ast::IntTy::I8 }
 318     impl_to_tokens_int! { signed, i16, ast::IntTy::I16 }
 319     impl_to_tokens_int! { signed, i32, ast::IntTy::I32 }
 320     impl_to_tokens_int! { signed, i64, ast::IntTy::I64 }
 321
 322     impl_to_tokens_int! { unsigned, usize, ast::UintTy::Us }
 323     impl_to_tokens_int! { unsigned, u8,   ast::UintTy::U8 }
 324     impl_to_tokens_int! { unsigned, u16,  ast::UintTy::U16 }
 325     impl_to_tokens_int! { unsigned, u32,  ast::UintTy::U32 }
 326     impl_to_tokens_int! { unsigned, u64,  ast::UintTy::U64 }
 327
 328     pub trait ExtParseUtils {
 329         fn parse_item(&self, s: String) -> P<ast::Item>;
 330         fn parse_expr(&self, s: String) -> P<ast::Expr>;
 331         fn parse_stmt(&self, s: String) -> ast::Stmt;
 332         fn parse_tts(&self, s: String) -> Vec<TokenTree>;
 333     }
 334
 335     impl<'a> ExtParseUtils for ExtCtxt<'a> {
 336         fn parse_item(&self, s: String) -> P<ast::Item> {
 337             panictry!(parse::parse_item_from_source_str(
 338                 "<quote expansion>".to_string(),
 339                 s,
 340                 self.parse_sess())).expect("parse error")
 341         }
 342
 343         fn parse_stmt(&self, s: String) -> ast::Stmt {
 344             panictry!(parse::parse_stmt_from_source_str(
 345                 "<quote expansion>".to_string(),
 346                 s,
 347                 self.parse_sess())).expect("parse error")
 348         }
 349
 350         fn parse_expr(&self, s: String) -> P<ast::Expr> {
 351             panictry!(parse::parse_expr_from_source_str(
 352                 "<quote expansion>".to_string(),
 353                 s,
 354                 self.parse_sess()))
 355         }
 356
 357         fn parse_tts(&self, s: String) -> Vec<TokenTree> {
 358             let source_name = "<quote expansion>".to_owned();
 359             parse::parse_stream_from_source_str(source_name, s, self.parse_sess())
 360                 .into_trees().collect()
 361         }
 362     }
 363 }
 364
 365 // Replaces `Token::OpenDelim .. Token::CloseDelim` with `TokenTree::Delimited(..)`.
 366 pub fn unflatten(tts: Vec<TokenTree>) -> Vec<TokenTree> {
 367     use tokenstream::Delimited;
 368
 369     let mut results = Vec::new();
 370     let mut result = Vec::new();
 371     for tree in tts {
 372         match tree {
 373             TokenTree::Token(_, token::OpenDelim(..)) => {
 374                 results.push(::std::mem::replace(&mut result, Vec::new()));
 375             }
 376             TokenTree::Token(span, token::CloseDelim(delim)) => {
 377                 let tree = TokenTree::Delimited(span, Delimited {
 378                     delim: delim,
 379                     tts: result.into_iter().map(TokenStream::from).collect::<TokenStream>().into(),
 380                 });
 381                 result = results.pop().unwrap();
 382                 result.push(tree);
 383             }
 384             tree @ _ => result.push(tree),
 385         }
 386     }
 387     result
 388 }
 389
 390 // These panicking parsing functions are used by the quote_*!() syntax extensions,
 391 // but shouldn't be used otherwise.
 392 pub fn parse_expr_panic(parser: &mut Parser) -> P<Expr> {
 393     panictry!(parser.parse_expr())
 394 }
 395
 396 pub fn parse_item_panic(parser: &mut Parser) -> Option<P<Item>> {
 397     panictry!(parser.parse_item())
 398 }
 399
 400 pub fn parse_pat_panic(parser: &mut Parser) -> P<Pat> {
 401     panictry!(parser.parse_pat())
 402 }
 403
 404 pub fn parse_arm_panic(parser: &mut Parser) -> Arm {
 405     panictry!(parser.parse_arm())
 406 }
 407
 408 pub fn parse_ty_panic(parser: &mut Parser) -> P<Ty> {
 409     panictry!(parser.parse_ty_no_plus())
 410 }
 411
 412 pub fn parse_stmt_panic(parser: &mut Parser) -> Option<Stmt> {
 413     panictry!(parser.parse_stmt())
 414 }
 415
 416 pub fn parse_attribute_panic(parser: &mut Parser, permit_inner: bool) -> ast::Attribute {
 417     panictry!(parser.parse_attribute(permit_inner))
 418 }
 419
 420 pub fn parse_arg_panic(parser: &mut Parser) -> Arg {
 421     panictry!(parser.parse_arg())
 422 }
 423
 424 pub fn parse_block_panic(parser: &mut Parser) -> P<Block> {
 425     panictry!(parser.parse_block())
 426 }
 427
 428 pub fn parse_meta_item_panic(parser: &mut Parser) -> ast::MetaItem {
 429     panictry!(parser.parse_meta_item())
 430 }
 431
 432 pub fn parse_path_panic(parser: &mut Parser, mode: PathStyle) -> ast::Path {
 433     panictry!(parser.parse_path(mode))
 434 }
 435
 436 pub fn expand_quote_tokens<'cx>(cx: &'cx mut ExtCtxt,
 437                                 sp: Span,
 438                                 tts: &[TokenTree])
 439                                 -> Box<base::MacResult+'cx> {
 440     let (cx_expr, expr) = expand_tts(cx, sp, tts);
 441     let expanded = expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"]]);
 442     base::MacEager::expr(expanded)
 443 }
 444
 445 pub fn expand_quote_expr<'cx>(cx: &'cx mut ExtCtxt,
 446                               sp: Span,
 447                               tts: &[TokenTree])
 448                               -> Box<base::MacResult+'cx> {
 449     let expanded = expand_parse_call(cx, sp, "parse_expr_panic", vec![], tts);
 450     base::MacEager::expr(expanded)
 451 }
 452
 453 pub fn expand_quote_item<'cx>(cx: &'cx mut ExtCtxt,
 454                               sp: Span,
 455                               tts: &[TokenTree])
 456                               -> Box<base::MacResult+'cx> {
 457     let expanded = expand_parse_call(cx, sp, "parse_item_panic", vec![], tts);
 458     base::MacEager::expr(expanded)
 459 }
 460
 461 pub fn expand_quote_pat<'cx>(cx: &'cx mut ExtCtxt,
 462                              sp: Span,
 463                              tts: &[TokenTree])
 464                              -> Box<base::MacResult+'cx> {
 465     let expanded = expand_parse_call(cx, sp, "parse_pat_panic", vec![], tts);
 466     base::MacEager::expr(expanded)
 467 }
 468
 469 pub fn expand_quote_arm(cx: &mut ExtCtxt,
 470                         sp: Span,
 471                         tts: &[TokenTree])
 472                         -> Box<base::MacResult+'static> {
 473     let expanded = expand_parse_call(cx, sp, "parse_arm_panic", vec![], tts);
 474     base::MacEager::expr(expanded)
 475 }
 476
 477 pub fn expand_quote_ty(cx: &mut ExtCtxt,
 478                        sp: Span,
 479                        tts: &[TokenTree])
 480                        -> Box<base::MacResult+'static> {
 481     let expanded = expand_parse_call(cx, sp, "parse_ty_panic", vec![], tts);
 482     base::MacEager::expr(expanded)
 483 }
 484
 485 pub fn expand_quote_stmt(cx: &mut ExtCtxt,
 486                          sp: Span,
 487                          tts: &[TokenTree])
 488                          -> Box<base::MacResult+'static> {
 489     let expanded = expand_parse_call(cx, sp, "parse_stmt_panic", vec![], tts);
 490     base::MacEager::expr(expanded)
 491 }
 492
 493 pub fn expand_quote_attr(cx: &mut ExtCtxt,
 494                          sp: Span,
 495                          tts: &[TokenTree])
 496                          -> Box<base::MacResult+'static> {
 497     let expanded = expand_parse_call(cx, sp, "parse_attribute_panic",
 498                                     vec![cx.expr_bool(sp, true)], tts);
 499
 500     base::MacEager::expr(expanded)
 501 }
 502
 503 pub fn expand_quote_arg(cx: &mut ExtCtxt,
 504                         sp: Span,
 505                         tts: &[TokenTree])
 506                         -> Box<base::MacResult+'static> {
 507     let expanded = expand_parse_call(cx, sp, "parse_arg_panic", vec![], tts);
 508     base::MacEager::expr(expanded)
 509 }
 510
 511 pub fn expand_quote_block(cx: &mut ExtCtxt,
 512                         sp: Span,
 513                         tts: &[TokenTree])
 514                         -> Box<base::MacResult+'static> {
 515     let expanded = expand_parse_call(cx, sp, "parse_block_panic", vec![], tts);
 516     base::MacEager::expr(expanded)
 517 }
 518
 519 pub fn expand_quote_meta_item(cx: &mut ExtCtxt,
 520                         sp: Span,
 521                         tts: &[TokenTree])
 522                         -> Box<base::MacResult+'static> {
 523     let expanded = expand_parse_call(cx, sp, "parse_meta_item_panic", vec![], tts);
 524     base::MacEager::expr(expanded)
 525 }
 526
 527 pub fn expand_quote_path(cx: &mut ExtCtxt,
 528                         sp: Span,
 529                         tts: &[TokenTree])
 530                         -> Box<base::MacResult+'static> {
 531     let mode = mk_parser_path(cx, sp, &["PathStyle", "Type"]);
 532     let expanded = expand_parse_call(cx, sp, "parse_path_panic", vec![mode], tts);
 533     base::MacEager::expr(expanded)
 534 }
 535
 536 fn ids_ext(strs: Vec<String>) -> Vec<ast::Ident> {
 537     strs.iter().map(|s| ast::Ident::from_str(s)).collect()
 538 }
 539
 540 fn id_ext(s: &str) -> ast::Ident {
 541     ast::Ident::from_str(s)
 542 }
 543
 544 // Lift an ident to the expr that evaluates to that ident.
 545 fn mk_ident(cx: &ExtCtxt, sp: Span, ident: ast::Ident) -> P<ast::Expr> {
 546     let e_str = cx.expr_str(sp, ident.name);
 547     cx.expr_method_call(sp,
 548                         cx.expr_ident(sp, id_ext("ext_cx")),
 549                         id_ext("ident_of"),
 550                         vec![e_str])
 551 }
 552
 553 // Lift a name to the expr that evaluates to that name
 554 fn mk_name(cx: &ExtCtxt, sp: Span, ident: ast::Ident) -> P<ast::Expr> {
 555     let e_str = cx.expr_str(sp, ident.name);
 556     cx.expr_method_call(sp,
 557                         cx.expr_ident(sp, id_ext("ext_cx")),
 558                         id_ext("name_of"),
 559                         vec![e_str])
 560 }
 561
 562 fn mk_tt_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 563     let idents = vec![id_ext("syntax"), id_ext("tokenstream"), id_ext("TokenTree"), id_ext(name)];
 564     cx.expr_path(cx.path_global(sp, idents))
 565 }
 566
 567 fn mk_token_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 568     let idents = vec![id_ext("syntax"), id_ext("parse"), id_ext("token"), id_ext(name)];
 569     cx.expr_path(cx.path_global(sp, idents))
 570 }
 571
 572 fn mk_parser_path(cx: &ExtCtxt, sp: Span, names: &[&str]) -> P<ast::Expr> {
 573     let mut idents = vec![id_ext("syntax"), id_ext("parse"), id_ext("parser")];
 574     idents.extend(names.iter().cloned().map(id_ext));
 575     cx.expr_path(cx.path_global(sp, idents))
 576 }
 577
 578 fn mk_binop(cx: &ExtCtxt, sp: Span, bop: token::BinOpToken) -> P<ast::Expr> {
 579     let name = match bop {
 580         token::Plus     => "Plus",
 581         token::Minus    => "Minus",
 582         token::Star     => "Star",
 583         token::Slash    => "Slash",
 584         token::Percent  => "Percent",
 585         token::Caret    => "Caret",
 586         token::And      => "And",
 587         token::Or       => "Or",
 588         token::Shl      => "Shl",
 589         token::Shr      => "Shr"
 590     };
 591     mk_token_path(cx, sp, name)
 592 }
 593
 594 fn mk_delim(cx: &ExtCtxt, sp: Span, delim: token::DelimToken) -> P<ast::Expr> {
 595     let name = match delim {
 596         token::Paren   => "Paren",
 597         token::Bracket => "Bracket",
 598         token::Brace   => "Brace",
 599         token::NoDelim => "NoDelim",
 600     };
 601     mk_token_path(cx, sp, name)
 602 }
 603
 604 #[allow(non_upper_case_globals)]
 605 fn expr_mk_token(cx: &ExtCtxt, sp: Span, tok: &token::Token) -> P<ast::Expr> {
 606     macro_rules! mk_lit {
 607         ($name: expr, $suffix: expr, $($args: expr),*) => {{
 608             let inner = cx.expr_call(sp, mk_token_path(cx, sp, $name), vec![$($args),*]);
 609             let suffix = match $suffix {
 610                 Some(name) => cx.expr_some(sp, mk_name(cx, sp, ast::Ident::with_empty_ctxt(name))),
 611                 None => cx.expr_none(sp)
 612             };
 613             cx.expr_call(sp, mk_token_path(cx, sp, "Literal"), vec![inner, suffix])
 614         }}
 615     }
 616     match *tok {
 617         token::BinOp(binop) => {
 618             return cx.expr_call(sp, mk_token_path(cx, sp, "BinOp"), vec![mk_binop(cx, sp, binop)]);
 619         }
 620         token::BinOpEq(binop) => {
 621             return cx.expr_call(sp, mk_token_path(cx, sp, "BinOpEq"),
 622                                 vec![mk_binop(cx, sp, binop)]);
 623         }
 624
 625         token::OpenDelim(delim) => {
 626             return cx.expr_call(sp, mk_token_path(cx, sp, "OpenDelim"),
 627                                 vec![mk_delim(cx, sp, delim)]);
 628         }
 629         token::CloseDelim(delim) => {
 630             return cx.expr_call(sp, mk_token_path(cx, sp, "CloseDelim"),
 631                                 vec![mk_delim(cx, sp, delim)]);
 632         }
 633
 634         token::Literal(token::Byte(i), suf) => {
 635             let e_byte = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 636             return mk_lit!("Byte", suf, e_byte);
 637         }
 638
 639         token::Literal(token::Char(i), suf) => {
 640             let e_char = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 641             return mk_lit!("Char", suf, e_char);
 642         }
 643
 644         token::Literal(token::Integer(i), suf) => {
 645             let e_int = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 646             return mk_lit!("Integer", suf, e_int);
 647         }
 648
 649         token::Literal(token::Float(fident), suf) => {
 650             let e_fident = mk_name(cx, sp, ast::Ident::with_empty_ctxt(fident));
 651             return mk_lit!("Float", suf, e_fident);
 652         }
 653
 654         token::Literal(token::Str_(ident), suf) => {
 655             return mk_lit!("Str_", suf, mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident)))
 656         }
 657
 658         token::Literal(token::StrRaw(ident, n), suf) => {
 659             return mk_lit!("StrRaw", suf, mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident)),
 660                            cx.expr_usize(sp, n))
 661         }
 662
 663         token::Ident(ident) => {
 664             return cx.expr_call(sp,
 665                                 mk_token_path(cx, sp, "Ident"),
 666                                 vec![mk_ident(cx, sp, ident)]);
 667         }
 668
 669         token::Lifetime(ident) => {
 670             return cx.expr_call(sp,
 671                                 mk_token_path(cx, sp, "Lifetime"),
 672                                 vec![mk_ident(cx, sp, ident)]);
 673         }
 674
 675         token::DocComment(ident) => {
 676             return cx.expr_call(sp,
 677                                 mk_token_path(cx, sp, "DocComment"),
 678                                 vec![mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident))]);
 679         }
 680
 681         token::Interpolated(_) => panic!("quote! with interpolated token"),
 682
 683         _ => ()
 684     }
 685
 686     let name = match *tok {
 687         token::Eq           => "Eq",
 688         token::Lt           => "Lt",
 689         token::Le           => "Le",
 690         token::EqEq         => "EqEq",
 691         token::Ne           => "Ne",
 692         token::Ge           => "Ge",
 693         token::Gt           => "Gt",
 694         token::AndAnd       => "AndAnd",
 695         token::OrOr         => "OrOr",
 696         token::Not          => "Not",
 697         token::Tilde        => "Tilde",
 698         token::At           => "At",
 699         token::Dot          => "Dot",
 700         token::DotDot       => "DotDot",
 701         token::Comma        => "Comma",
 702         token::Semi         => "Semi",
 703         token::Colon        => "Colon",
 704         token::ModSep       => "ModSep",
 705         token::RArrow       => "RArrow",
 706         token::LArrow       => "LArrow",
 707         token::FatArrow     => "FatArrow",
 708         token::Pound        => "Pound",
 709         token::Dollar       => "Dollar",
 710         token::Question     => "Question",
 711         token::Underscore   => "Underscore",
 712         token::Eof          => "Eof",
 713         _                   => panic!("unhandled token in quote!"),
 714     };
 715     mk_token_path(cx, sp, name)
 716 }
 717
 718 fn statements_mk_tt(cx: &ExtCtxt, tt: &TokenTree, quoted: bool) -> Vec<ast::Stmt> {
 719     match *tt {
 720         TokenTree::Token(sp, token::Ident(ident)) if quoted => {
 721             // tt.extend($ident.to_tokens(ext_cx))
 722
 723             let e_to_toks =
 724                 cx.expr_method_call(sp,
 725                                     cx.expr_ident(sp, ident),
 726                                     id_ext("to_tokens"),
 727                                     vec![cx.expr_ident(sp, id_ext("ext_cx"))]);
 728             let e_to_toks =
 729                 cx.expr_method_call(sp, e_to_toks, id_ext("into_iter"), vec![]);
 730
 731             let e_push =
 732                 cx.expr_method_call(sp,
 733                                     cx.expr_ident(sp, id_ext("tt")),
 734                                     id_ext("extend"),
 735                                     vec![e_to_toks]);
 736
 737             vec![cx.stmt_expr(e_push)]
 738         }
 739         TokenTree::Token(sp, ref tok) => {
 740             let e_sp = cx.expr_ident(sp, id_ext("_sp"));
 741             let e_tok = cx.expr_call(sp,
 742                                      mk_tt_path(cx, sp, "Token"),
 743                                      vec![e_sp, expr_mk_token(cx, sp, tok)]);
 744             let e_push =
 745                 cx.expr_method_call(sp,
 746                                     cx.expr_ident(sp, id_ext("tt")),
 747                                     id_ext("push"),
 748                                     vec![e_tok]);
 749             vec![cx.stmt_expr(e_push)]
 750         },
 751         TokenTree::Delimited(span, ref delimed) => {
 752             let mut stmts = statements_mk_tt(cx, &delimed.open_tt(span), false);
 753             stmts.extend(statements_mk_tts(cx, delimed.stream()));
 754             stmts.extend(statements_mk_tt(cx, &delimed.close_tt(span), false));
 755             stmts
 756         }
 757     }
 758 }
 759
 760 fn parse_arguments_to_quote(cx: &ExtCtxt, tts: &[TokenTree])
 761                             -> (P<ast::Expr>, Vec<TokenTree>) {
 762     let mut p = cx.new_parser_from_tts(tts);
 763
 764     let cx_expr = panictry!(p.parse_expr());
 765     if !p.eat(&token::Comma) {
 766         let _ = p.diagnostic().fatal("expected token `,`");
 767     }
 768
 769     let tts = panictry!(p.parse_all_token_trees());
 770     p.abort_if_errors();
 771
 772     (cx_expr, tts)
 773 }
 774
 775 fn mk_stmts_let(cx: &ExtCtxt, sp: Span) -> Vec<ast::Stmt> {
 776     // We also bind a single value, sp, to ext_cx.call_site()
 777     //
 778     // This causes every span in a token-tree quote to be attributed to the
 779     // call site of the extension using the quote. We can't really do much
 780     // better since the source of the quote may well be in a library that
 781     // was not even parsed by this compilation run, that the user has no
 782     // source code for (eg. in libsyntax, which they're just _using_).
 783     //
 784     // The old quasiquoter had an elaborate mechanism for denoting input
 785     // file locations from which quotes originated; unfortunately this
 786     // relied on feeding the source string of the quote back into the
 787     // compiler (which we don't really want to do) and, in any case, only
 788     // pushed the problem a very small step further back: an error
 789     // resulting from a parse of the resulting quote is still attributed to
 790     // the site the string literal occurred, which was in a source file
 791     // _other_ than the one the user has control over. For example, an
 792     // error in a quote from the protocol compiler, invoked in user code
 793     // using macro_rules! for example, will be attributed to the macro_rules.rs
 794     // file in libsyntax, which the user might not even have source to (unless
 795     // they happen to have a compiler on hand). Over all, the phase distinction
 796     // just makes quotes "hard to attribute". Possibly this could be fixed
 797     // by recreating some of the original qq machinery in the tt regime
 798     // (pushing fake FileMaps onto the parser to account for original sites
 799     // of quotes, for example) but at this point it seems not likely to be
 800     // worth the hassle.
 801
 802     let e_sp = cx.expr_method_call(sp,
 803                                    cx.expr_ident(sp, id_ext("ext_cx")),
 804                                    id_ext("call_site"),
 805                                    Vec::new());
 806
 807     let stmt_let_sp = cx.stmt_let(sp, false,
 808                                   id_ext("_sp"),
 809                                   e_sp);
 810
 811     let stmt_let_tt = cx.stmt_let(sp, true, id_ext("tt"), cx.expr_vec_ng(sp));
 812
 813     vec![stmt_let_sp, stmt_let_tt]
 814 }
 815
 816 fn statements_mk_tts(cx: &ExtCtxt, tts: TokenStream) -> Vec<ast::Stmt> {
 817     let mut ss = Vec::new();
 818     let mut quoted = false;
 819     for tt in tts.into_trees() {
 820         quoted = match tt {
 821             TokenTree::Token(_, token::Dollar) if !quoted => true,
 822             _ => {
 823                 ss.extend(statements_mk_tt(cx, &tt, quoted));
 824                 false
 825             }
 826         }
 827     }
 828     ss
 829 }
 830
 831 fn expand_tts(cx: &ExtCtxt, sp: Span, tts: &[TokenTree]) -> (P<ast::Expr>, P<ast::Expr>) {
 832     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
 833
 834     let mut vector = mk_stmts_let(cx, sp);
 835     vector.extend(statements_mk_tts(cx, tts.iter().cloned().collect()));
 836     vector.push(cx.stmt_expr(cx.expr_ident(sp, id_ext("tt"))));
 837     let block = cx.expr_block(cx.block(sp, vector));
 838     let unflatten = vec![id_ext("syntax"), id_ext("ext"), id_ext("quote"), id_ext("unflatten")];
 839
 840     (cx_expr, cx.expr_call_global(sp, unflatten, vec![block]))
 841 }
 842
 843 fn expand_wrapper(cx: &ExtCtxt,
 844                   sp: Span,
 845                   cx_expr: P<ast::Expr>,
 846                   expr: P<ast::Expr>,
 847                   imports: &[&[&str]]) -> P<ast::Expr> {
 848     // Explicitly borrow to avoid moving from the invoker (#16992)
 849     let cx_expr_borrow = cx.expr_addr_of(sp, cx.expr_deref(sp, cx_expr));
 850     let stmt_let_ext_cx = cx.stmt_let(sp, false, id_ext("ext_cx"), cx_expr_borrow);
 851
 852     let mut stmts = imports.iter().map(|path| {
 853         // make item: `use ...;`
 854         let path = path.iter().map(|s| s.to_string()).collect();
 855         cx.stmt_item(sp, cx.item_use_glob(sp, ast::Visibility::Inherited, ids_ext(path)))
 856     }).chain(Some(stmt_let_ext_cx)).collect::<Vec<_>>();
 857     stmts.push(cx.stmt_expr(expr));
 858
 859     cx.expr_block(cx.block(sp, stmts))
 860 }
 861
 862 fn expand_parse_call(cx: &ExtCtxt,
 863                      sp: Span,
 864                      parse_method: &str,
 865                      arg_exprs: Vec<P<ast::Expr>> ,
 866                      tts: &[TokenTree]) -> P<ast::Expr> {
 867     let (cx_expr, tts_expr) = expand_tts(cx, sp, tts);
 868
 869     let parse_sess_call = || cx.expr_method_call(
 870         sp, cx.expr_ident(sp, id_ext("ext_cx")),
 871         id_ext("parse_sess"), Vec::new());
 872
 873     let new_parser_call =
 874         cx.expr_call(sp,
 875                      cx.expr_ident(sp, id_ext("new_parser_from_tts")),
 876                      vec![parse_sess_call(), tts_expr]);
 877
 878     let path = vec![id_ext("syntax"), id_ext("ext"), id_ext("quote"), id_ext(parse_method)];
 879     let mut args = vec![cx.expr_mut_addr_of(sp, new_parser_call)];
 880     args.extend(arg_exprs);
 881     let expr = cx.expr_call_global(sp, path, args);
 882
 883     if parse_method == "parse_attribute" {
 884         expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"],
 885                                                 &["syntax", "parse", "attr"]])
 886     } else {
 887         expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"]])
 888     }
 889 }