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;
  12 use codemap::Span;
  13 use ext::base::ExtCtxt;
  14 use ext::base;
  15 use ext::build::AstBuilder;
  16 use parse::token::*;
  17 use parse::token;
  18 use ptr::P;
  19
  20 ///  Quasiquoting works via token trees.
  21 ///
  22 ///  This is registered as a set of expression syntax extension called quote!
  23 ///  that lifts its argument token-tree to an AST representing the
  24 ///  construction of the same token tree, with token::SubstNt interpreted
  25 ///  as antiquotes (splices).
  26
  27 pub mod rt {
  28     use ast;
  29     use codemap::Spanned;
  30     use ext::base::ExtCtxt;
  31     use parse::{self, token, classify};
  32     use ptr::P;
  33     use std::rc::Rc;
  34
  35     use ast::{TokenTree, Expr};
  36
  37     pub use parse::new_parser_from_tts;
  38     pub use codemap::{BytePos, Span, dummy_spanned, DUMMY_SP};
  39
  40     pub trait ToTokens {
  41         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree>;
  42     }
  43
  44     impl ToTokens for TokenTree {
  45         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  46             vec!(self.clone())
  47         }
  48     }
  49
  50     impl<T: ToTokens> ToTokens for Vec<T> {
  51         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
  52             self.iter().flat_map(|t| t.to_tokens(cx)).collect()
  53         }
  54     }
  55
  56     impl<T: ToTokens> ToTokens for Spanned<T> {
  57         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
  58             // FIXME: use the span?
  59             self.node.to_tokens(cx)
  60         }
  61     }
  62
  63     impl<T: ToTokens> ToTokens for Option<T> {
  64         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
  65             match self {
  66                 &Some(ref t) => t.to_tokens(cx),
  67                 &None => Vec::new(),
  68             }
  69         }
  70     }
  71
  72     impl ToTokens for ast::Ident {
  73         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  74             vec![ast::TtToken(DUMMY_SP, token::Ident(*self, token::Plain))]
  75         }
  76     }
  77
  78     impl ToTokens for ast::Path {
  79         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  80             vec![ast::TtToken(DUMMY_SP, token::Interpolated(token::NtPath(Box::new(self.clone()))))]
  81         }
  82     }
  83
  84     impl ToTokens for ast::Ty {
  85         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  86             vec![ast::TtToken(self.span, token::Interpolated(token::NtTy(P(self.clone()))))]
  87         }
  88     }
  89
  90     impl ToTokens for ast::Block {
  91         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  92             vec![ast::TtToken(self.span, token::Interpolated(token::NtBlock(P(self.clone()))))]
  93         }
  94     }
  95
  96     impl ToTokens for ast::Generics {
  97         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  98             vec![ast::TtToken(DUMMY_SP, token::Interpolated(token::NtGenerics(self.clone())))]
  99         }
 100     }
 101
 102     impl ToTokens for ast::WhereClause {
 103         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 104             vec![ast::TtToken(DUMMY_SP, token::Interpolated(token::NtWhereClause(self.clone())))]
 105         }
 106     }
 107
 108     impl ToTokens for P<ast::Item> {
 109         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 110             vec![ast::TtToken(self.span, token::Interpolated(token::NtItem(self.clone())))]
 111         }
 112     }
 113
 114     impl ToTokens for P<ast::ImplItem> {
 115         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 116             vec![ast::TtToken(self.span, token::Interpolated(token::NtImplItem(self.clone())))]
 117         }
 118     }
 119
 120     impl ToTokens for P<ast::TraitItem> {
 121         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 122             vec![ast::TtToken(self.span, token::Interpolated(token::NtTraitItem(self.clone())))]
 123         }
 124     }
 125
 126     impl ToTokens for P<ast::Stmt> {
 127         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 128             let mut tts = vec![
 129                 ast::TtToken(self.span, token::Interpolated(token::NtStmt(self.clone())))
 130             ];
 131
 132             // Some statements require a trailing semicolon.
 133             if classify::stmt_ends_with_semi(&self.node) {
 134                 tts.push(ast::TtToken(self.span, token::Semi));
 135             }
 136
 137             tts
 138         }
 139     }
 140
 141     impl ToTokens for P<ast::Expr> {
 142         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 143             vec![ast::TtToken(self.span, token::Interpolated(token::NtExpr(self.clone())))]
 144         }
 145     }
 146
 147     impl ToTokens for P<ast::Pat> {
 148         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 149             vec![ast::TtToken(self.span, token::Interpolated(token::NtPat(self.clone())))]
 150         }
 151     }
 152
 153     impl ToTokens for ast::Arm {
 154         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 155             vec![ast::TtToken(DUMMY_SP, token::Interpolated(token::NtArm(self.clone())))]
 156         }
 157     }
 158
 159     macro_rules! impl_to_tokens_slice {
 160         ($t: ty, $sep: expr) => {
 161             impl ToTokens for [$t] {
 162                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 163                     let mut v = vec![];
 164                     for (i, x) in self.iter().enumerate() {
 165                         if i > 0 {
 166                             v.push_all(&$sep);
 167                         }
 168                         v.extend(x.to_tokens(cx));
 169                     }
 170                     v
 171                 }
 172             }
 173         };
 174     }
 175
 176     impl_to_tokens_slice! { ast::Ty, [ast::TtToken(DUMMY_SP, token::Comma)] }
 177     impl_to_tokens_slice! { P<ast::Item>, [] }
 178
 179     impl ToTokens for P<ast::MetaItem> {
 180         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 181             vec![ast::TtToken(DUMMY_SP, token::Interpolated(token::NtMeta(self.clone())))]
 182         }
 183     }
 184
 185     impl ToTokens for ast::Attribute {
 186         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 187             let mut r = vec![];
 188             // FIXME: The spans could be better
 189             r.push(ast::TtToken(self.span, token::Pound));
 190             if self.node.style == ast::AttrInner {
 191                 r.push(ast::TtToken(self.span, token::Not));
 192             }
 193             r.push(ast::TtDelimited(self.span, Rc::new(ast::Delimited {
 194                 delim: token::Bracket,
 195                 open_span: self.span,
 196                 tts: self.node.value.to_tokens(cx),
 197                 close_span: self.span,
 198             })));
 199             r
 200         }
 201     }
 202
 203     impl ToTokens for str {
 204         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 205             let lit = ast::LitStr(
 206                 token::intern_and_get_ident(self), ast::CookedStr);
 207             dummy_spanned(lit).to_tokens(cx)
 208         }
 209     }
 210
 211     impl ToTokens for () {
 212         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 213             vec![ast::TtDelimited(DUMMY_SP, Rc::new(ast::Delimited {
 214                 delim: token::Paren,
 215                 open_span: DUMMY_SP,
 216                 tts: vec![],
 217                 close_span: DUMMY_SP,
 218             }))]
 219         }
 220     }
 221
 222     impl ToTokens for ast::Lit {
 223         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 224             // FIXME: This is wrong
 225             P(ast::Expr {
 226                 id: ast::DUMMY_NODE_ID,
 227                 node: ast::ExprLit(P(self.clone())),
 228                 span: DUMMY_SP,
 229             }).to_tokens(cx)
 230         }
 231     }
 232
 233     impl ToTokens for bool {
 234         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 235             dummy_spanned(ast::LitBool(*self)).to_tokens(cx)
 236         }
 237     }
 238
 239     impl ToTokens for char {
 240         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 241             dummy_spanned(ast::LitChar(*self)).to_tokens(cx)
 242         }
 243     }
 244
 245     macro_rules! impl_to_tokens_int {
 246         (signed, $t:ty, $tag:expr) => (
 247             impl ToTokens for $t {
 248                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 249                     let lit = ast::LitInt(*self as u64, ast::SignedIntLit($tag,
 250                                                                           ast::Sign::new(*self)));
 251                     dummy_spanned(lit).to_tokens(cx)
 252                 }
 253             }
 254         );
 255         (unsigned, $t:ty, $tag:expr) => (
 256             impl ToTokens for $t {
 257                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 258                     let lit = ast::LitInt(*self as u64, ast::UnsignedIntLit($tag));
 259                     dummy_spanned(lit).to_tokens(cx)
 260                 }
 261             }
 262         );
 263     }
 264
 265     impl_to_tokens_int! { signed, isize, ast::TyIs }
 266     impl_to_tokens_int! { signed, i8,  ast::TyI8 }
 267     impl_to_tokens_int! { signed, i16, ast::TyI16 }
 268     impl_to_tokens_int! { signed, i32, ast::TyI32 }
 269     impl_to_tokens_int! { signed, i64, ast::TyI64 }
 270
 271     impl_to_tokens_int! { unsigned, usize, ast::TyUs }
 272     impl_to_tokens_int! { unsigned, u8,   ast::TyU8 }
 273     impl_to_tokens_int! { unsigned, u16,  ast::TyU16 }
 274     impl_to_tokens_int! { unsigned, u32,  ast::TyU32 }
 275     impl_to_tokens_int! { unsigned, u64,  ast::TyU64 }
 276
 277     pub trait ExtParseUtils {
 278         fn parse_item(&self, s: String) -> P<ast::Item>;
 279         fn parse_expr(&self, s: String) -> P<ast::Expr>;
 280         fn parse_stmt(&self, s: String) -> P<ast::Stmt>;
 281         fn parse_tts(&self, s: String) -> Vec<ast::TokenTree>;
 282     }
 283
 284     impl<'a> ExtParseUtils for ExtCtxt<'a> {
 285
 286         fn parse_item(&self, s: String) -> P<ast::Item> {
 287             parse::parse_item_from_source_str(
 288                 "<quote expansion>".to_string(),
 289                 s,
 290                 self.cfg(),
 291                 self.parse_sess()).expect("parse error")
 292         }
 293
 294         fn parse_stmt(&self, s: String) -> P<ast::Stmt> {
 295             parse::parse_stmt_from_source_str("<quote expansion>".to_string(),
 296                                               s,
 297                                               self.cfg(),
 298                                               self.parse_sess()).expect("parse error")
 299         }
 300
 301         fn parse_expr(&self, s: String) -> P<ast::Expr> {
 302             parse::parse_expr_from_source_str("<quote expansion>".to_string(),
 303                                               s,
 304                                               self.cfg(),
 305                                               self.parse_sess())
 306         }
 307
 308         fn parse_tts(&self, s: String) -> Vec<ast::TokenTree> {
 309             parse::parse_tts_from_source_str("<quote expansion>".to_string(),
 310                                              s,
 311                                              self.cfg(),
 312                                              self.parse_sess())
 313         }
 314     }
 315 }
 316
 317 pub fn expand_quote_tokens<'cx>(cx: &'cx mut ExtCtxt,
 318                                 sp: Span,
 319                                 tts: &[ast::TokenTree])
 320                                 -> Box<base::MacResult+'cx> {
 321     let (cx_expr, expr) = expand_tts(cx, sp, tts);
 322     let expanded = expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"]]);
 323     base::MacEager::expr(expanded)
 324 }
 325
 326 pub fn expand_quote_expr<'cx>(cx: &'cx mut ExtCtxt,
 327                               sp: Span,
 328                               tts: &[ast::TokenTree])
 329                               -> Box<base::MacResult+'cx> {
 330     let expanded = expand_parse_call(cx, sp, "parse_expr", vec!(), tts);
 331     base::MacEager::expr(expanded)
 332 }
 333
 334 pub fn expand_quote_item<'cx>(cx: &mut ExtCtxt,
 335                               sp: Span,
 336                               tts: &[ast::TokenTree])
 337                               -> Box<base::MacResult+'cx> {
 338     let expanded = expand_parse_call(cx, sp, "parse_item", vec!(), tts);
 339     base::MacEager::expr(expanded)
 340 }
 341
 342 pub fn expand_quote_pat<'cx>(cx: &'cx mut ExtCtxt,
 343                              sp: Span,
 344                              tts: &[ast::TokenTree])
 345                              -> Box<base::MacResult+'cx> {
 346     let expanded = expand_parse_call(cx, sp, "parse_pat", vec!(), tts);
 347     base::MacEager::expr(expanded)
 348 }
 349
 350 pub fn expand_quote_arm(cx: &mut ExtCtxt,
 351                         sp: Span,
 352                         tts: &[ast::TokenTree])
 353                         -> Box<base::MacResult+'static> {
 354     let expanded = expand_parse_call(cx, sp, "parse_arm", vec!(), tts);
 355     base::MacEager::expr(expanded)
 356 }
 357
 358 pub fn expand_quote_ty(cx: &mut ExtCtxt,
 359                        sp: Span,
 360                        tts: &[ast::TokenTree])
 361                        -> Box<base::MacResult+'static> {
 362     let expanded = expand_parse_call(cx, sp, "parse_ty", vec!(), tts);
 363     base::MacEager::expr(expanded)
 364 }
 365
 366 pub fn expand_quote_stmt(cx: &mut ExtCtxt,
 367                          sp: Span,
 368                          tts: &[ast::TokenTree])
 369                          -> Box<base::MacResult+'static> {
 370     let expanded = expand_parse_call(cx, sp, "parse_stmt", vec!(), tts);
 371     base::MacEager::expr(expanded)
 372 }
 373
 374 pub fn expand_quote_attr(cx: &mut ExtCtxt,
 375                          sp: Span,
 376                          tts: &[ast::TokenTree])
 377                          -> Box<base::MacResult+'static> {
 378     let expanded = expand_parse_call(cx, sp, "parse_attribute",
 379                                     vec!(cx.expr_bool(sp, true)), tts);
 380
 381     base::MacEager::expr(expanded)
 382 }
 383
 384 pub fn expand_quote_matcher(cx: &mut ExtCtxt,
 385                             sp: Span,
 386                             tts: &[ast::TokenTree])
 387                             -> Box<base::MacResult+'static> {
 388     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
 389     let mut vector = mk_stmts_let(cx, sp);
 390     vector.extend(statements_mk_tts(cx, &tts[..], true));
 391     let block = cx.expr_block(
 392         cx.block_all(sp,
 393                      vector,
 394                      Some(cx.expr_ident(sp, id_ext("tt")))));
 395
 396     let expanded = expand_wrapper(cx, sp, cx_expr, block, &[&["syntax", "ext", "quote", "rt"]]);
 397     base::MacEager::expr(expanded)
 398 }
 399
 400 fn ids_ext(strs: Vec<String> ) -> Vec<ast::Ident> {
 401     strs.iter().map(|str| str_to_ident(&(*str))).collect()
 402 }
 403
 404 fn id_ext(str: &str) -> ast::Ident {
 405     str_to_ident(str)
 406 }
 407
 408 // Lift an ident to the expr that evaluates to that ident.
 409 fn mk_ident(cx: &ExtCtxt, sp: Span, ident: ast::Ident) -> P<ast::Expr> {
 410     let e_str = cx.expr_str(sp, ident.name.as_str());
 411     cx.expr_method_call(sp,
 412                         cx.expr_ident(sp, id_ext("ext_cx")),
 413                         id_ext("ident_of"),
 414                         vec!(e_str))
 415 }
 416
 417 // Lift a name to the expr that evaluates to that name
 418 fn mk_name(cx: &ExtCtxt, sp: Span, ident: ast::Ident) -> P<ast::Expr> {
 419     let e_str = cx.expr_str(sp, ident.name.as_str());
 420     cx.expr_method_call(sp,
 421                         cx.expr_ident(sp, id_ext("ext_cx")),
 422                         id_ext("name_of"),
 423                         vec!(e_str))
 424 }
 425
 426 fn mk_ast_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 427     let idents = vec!(id_ext("syntax"), id_ext("ast"), id_ext(name));
 428     cx.expr_path(cx.path_global(sp, idents))
 429 }
 430
 431 fn mk_token_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 432     let idents = vec!(id_ext("syntax"), id_ext("parse"), id_ext("token"), id_ext(name));
 433     cx.expr_path(cx.path_global(sp, idents))
 434 }
 435
 436 fn mk_binop(cx: &ExtCtxt, sp: Span, bop: token::BinOpToken) -> P<ast::Expr> {
 437     let name = match bop {
 438         token::Plus     => "Plus",
 439         token::Minus    => "Minus",
 440         token::Star     => "Star",
 441         token::Slash    => "Slash",
 442         token::Percent  => "Percent",
 443         token::Caret    => "Caret",
 444         token::And      => "And",
 445         token::Or       => "Or",
 446         token::Shl      => "Shl",
 447         token::Shr      => "Shr"
 448     };
 449     mk_token_path(cx, sp, name)
 450 }
 451
 452 fn mk_delim(cx: &ExtCtxt, sp: Span, delim: token::DelimToken) -> P<ast::Expr> {
 453     let name = match delim {
 454         token::Paren     => "Paren",
 455         token::Bracket   => "Bracket",
 456         token::Brace     => "Brace",
 457     };
 458     mk_token_path(cx, sp, name)
 459 }
 460
 461 #[allow(non_upper_case_globals)]
 462 fn expr_mk_token(cx: &ExtCtxt, sp: Span, tok: &token::Token) -> P<ast::Expr> {
 463     macro_rules! mk_lit {
 464         ($name: expr, $suffix: expr, $($args: expr),*) => {{
 465             let inner = cx.expr_call(sp, mk_token_path(cx, sp, $name), vec![$($args),*]);
 466             let suffix = match $suffix {
 467                 Some(name) => cx.expr_some(sp, mk_name(cx, sp, ast::Ident::with_empty_ctxt(name))),
 468                 None => cx.expr_none(sp)
 469             };
 470             cx.expr_call(sp, mk_token_path(cx, sp, "Literal"), vec![inner, suffix])
 471         }}
 472     }
 473     match *tok {
 474         token::BinOp(binop) => {
 475             return cx.expr_call(sp, mk_token_path(cx, sp, "BinOp"), vec!(mk_binop(cx, sp, binop)));
 476         }
 477         token::BinOpEq(binop) => {
 478             return cx.expr_call(sp, mk_token_path(cx, sp, "BinOpEq"),
 479                                 vec!(mk_binop(cx, sp, binop)));
 480         }
 481
 482         token::OpenDelim(delim) => {
 483             return cx.expr_call(sp, mk_token_path(cx, sp, "OpenDelim"),
 484                                 vec![mk_delim(cx, sp, delim)]);
 485         }
 486         token::CloseDelim(delim) => {
 487             return cx.expr_call(sp, mk_token_path(cx, sp, "CloseDelim"),
 488                                 vec![mk_delim(cx, sp, delim)]);
 489         }
 490
 491         token::Literal(token::Byte(i), suf) => {
 492             let e_byte = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 493             return mk_lit!("Byte", suf, e_byte);
 494         }
 495
 496         token::Literal(token::Char(i), suf) => {
 497             let e_char = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 498             return mk_lit!("Char", suf, e_char);
 499         }
 500
 501         token::Literal(token::Integer(i), suf) => {
 502             let e_int = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 503             return mk_lit!("Integer", suf, e_int);
 504         }
 505
 506         token::Literal(token::Float(fident), suf) => {
 507             let e_fident = mk_name(cx, sp, ast::Ident::with_empty_ctxt(fident));
 508             return mk_lit!("Float", suf, e_fident);
 509         }
 510
 511         token::Literal(token::Str_(ident), suf) => {
 512             return mk_lit!("Str_", suf, mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident)))
 513         }
 514
 515         token::Literal(token::StrRaw(ident, n), suf) => {
 516             return mk_lit!("StrRaw", suf, mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident)),
 517                            cx.expr_usize(sp, n))
 518         }
 519
 520         token::Ident(ident, style) => {
 521             return cx.expr_call(sp,
 522                                 mk_token_path(cx, sp, "Ident"),
 523                                 vec![mk_ident(cx, sp, ident),
 524                                      match style {
 525                                         ModName => mk_token_path(cx, sp, "ModName"),
 526                                         Plain   => mk_token_path(cx, sp, "Plain"),
 527                                      }]);
 528         }
 529
 530         token::Lifetime(ident) => {
 531             return cx.expr_call(sp,
 532                                 mk_token_path(cx, sp, "Lifetime"),
 533                                 vec!(mk_ident(cx, sp, ident)));
 534         }
 535
 536         token::DocComment(ident) => {
 537             return cx.expr_call(sp,
 538                                 mk_token_path(cx, sp, "DocComment"),
 539                                 vec!(mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident))));
 540         }
 541
 542         token::MatchNt(name, kind, namep, kindp) => {
 543             return cx.expr_call(sp,
 544                                 mk_token_path(cx, sp, "MatchNt"),
 545                                 vec!(mk_ident(cx, sp, name),
 546                                      mk_ident(cx, sp, kind),
 547                                      match namep {
 548                                         ModName => mk_token_path(cx, sp, "ModName"),
 549                                         Plain   => mk_token_path(cx, sp, "Plain"),
 550                                      },
 551                                      match kindp {
 552                                         ModName => mk_token_path(cx, sp, "ModName"),
 553                                         Plain   => mk_token_path(cx, sp, "Plain"),
 554                                      }));
 555         }
 556
 557         token::Interpolated(_) => panic!("quote! with interpolated token"),
 558
 559         _ => ()
 560     }
 561
 562     let name = match *tok {
 563         token::Eq           => "Eq",
 564         token::Lt           => "Lt",
 565         token::Le           => "Le",
 566         token::EqEq         => "EqEq",
 567         token::Ne           => "Ne",
 568         token::Ge           => "Ge",
 569         token::Gt           => "Gt",
 570         token::AndAnd       => "AndAnd",
 571         token::OrOr         => "OrOr",
 572         token::Not          => "Not",
 573         token::Tilde        => "Tilde",
 574         token::At           => "At",
 575         token::Dot          => "Dot",
 576         token::DotDot       => "DotDot",
 577         token::Comma        => "Comma",
 578         token::Semi         => "Semi",
 579         token::Colon        => "Colon",
 580         token::ModSep       => "ModSep",
 581         token::RArrow       => "RArrow",
 582         token::LArrow       => "LArrow",
 583         token::FatArrow     => "FatArrow",
 584         token::Pound        => "Pound",
 585         token::Dollar       => "Dollar",
 586         token::Question     => "Question",
 587         token::Underscore   => "Underscore",
 588         token::Eof          => "Eof",
 589         _                   => panic!("unhandled token in quote!"),
 590     };
 591     mk_token_path(cx, sp, name)
 592 }
 593
 594 fn statements_mk_tt(cx: &ExtCtxt, tt: &ast::TokenTree, matcher: bool) -> Vec<P<ast::Stmt>> {
 595     match *tt {
 596         ast::TtToken(sp, SubstNt(ident, _)) => {
 597             // tt.extend($ident.to_tokens(ext_cx))
 598
 599             let e_to_toks =
 600                 cx.expr_method_call(sp,
 601                                     cx.expr_ident(sp, ident),
 602                                     id_ext("to_tokens"),
 603                                     vec!(cx.expr_ident(sp, id_ext("ext_cx"))));
 604             let e_to_toks =
 605                 cx.expr_method_call(sp, e_to_toks, id_ext("into_iter"), vec![]);
 606
 607             let e_push =
 608                 cx.expr_method_call(sp,
 609                                     cx.expr_ident(sp, id_ext("tt")),
 610                                     id_ext("extend"),
 611                                     vec!(e_to_toks));
 612
 613             vec!(cx.stmt_expr(e_push))
 614         }
 615         ref tt @ ast::TtToken(_, MatchNt(..)) if !matcher => {
 616             let mut seq = vec![];
 617             for i in 0..tt.len() {
 618                 seq.push(tt.get_tt(i));
 619             }
 620             statements_mk_tts(cx, &seq[..], matcher)
 621         }
 622         ast::TtToken(sp, ref tok) => {
 623             let e_sp = cx.expr_ident(sp, id_ext("_sp"));
 624             let e_tok = cx.expr_call(sp,
 625                                      mk_ast_path(cx, sp, "TtToken"),
 626                                      vec!(e_sp, expr_mk_token(cx, sp, tok)));
 627             let e_push =
 628                 cx.expr_method_call(sp,
 629                                     cx.expr_ident(sp, id_ext("tt")),
 630                                     id_ext("push"),
 631                                     vec!(e_tok));
 632             vec!(cx.stmt_expr(e_push))
 633         },
 634         ast::TtDelimited(_, ref delimed) => {
 635             statements_mk_tt(cx, &delimed.open_tt(), matcher).into_iter()
 636                 .chain(delimed.tts.iter()
 637                                   .flat_map(|tt| statements_mk_tt(cx, tt, matcher)))
 638                 .chain(statements_mk_tt(cx, &delimed.close_tt(), matcher))
 639                 .collect()
 640         },
 641         ast::TtSequence(sp, ref seq) => {
 642             if !matcher {
 643                 panic!("TtSequence in quote!");
 644             }
 645
 646             let e_sp = cx.expr_ident(sp, id_ext("_sp"));
 647
 648             let stmt_let_tt = cx.stmt_let(sp, true, id_ext("tt"), cx.expr_vec_ng(sp));
 649             let mut tts_stmts = vec![stmt_let_tt];
 650             tts_stmts.extend(statements_mk_tts(cx, &seq.tts[..], matcher));
 651             let e_tts = cx.expr_block(cx.block(sp, tts_stmts,
 652                                                    Some(cx.expr_ident(sp, id_ext("tt")))));
 653             let e_separator = match seq.separator {
 654                 Some(ref sep) => cx.expr_some(sp, expr_mk_token(cx, sp, sep)),
 655                 None => cx.expr_none(sp),
 656             };
 657             let e_op = match seq.op {
 658                 ast::ZeroOrMore => mk_ast_path(cx, sp, "ZeroOrMore"),
 659                 ast::OneOrMore => mk_ast_path(cx, sp, "OneOrMore"),
 660             };
 661             let fields = vec![cx.field_imm(sp, id_ext("tts"), e_tts),
 662                               cx.field_imm(sp, id_ext("separator"), e_separator),
 663                               cx.field_imm(sp, id_ext("op"), e_op),
 664                               cx.field_imm(sp, id_ext("num_captures"),
 665                                                cx.expr_usize(sp, seq.num_captures))];
 666             let seq_path = vec![id_ext("syntax"), id_ext("ast"), id_ext("SequenceRepetition")];
 667             let e_seq_struct = cx.expr_struct(sp, cx.path_global(sp, seq_path), fields);
 668             let e_rc_new = cx.expr_call_global(sp, vec![id_ext("std"),
 669                                                         id_ext("rc"),
 670                                                         id_ext("Rc"),
 671                                                         id_ext("new")],
 672                                                    vec![e_seq_struct]);
 673             let e_tok = cx.expr_call(sp,
 674                                      mk_ast_path(cx, sp, "TtSequence"),
 675                                      vec!(e_sp, e_rc_new));
 676             let e_push =
 677                 cx.expr_method_call(sp,
 678                                     cx.expr_ident(sp, id_ext("tt")),
 679                                     id_ext("push"),
 680                                     vec!(e_tok));
 681             vec!(cx.stmt_expr(e_push))
 682         }
 683     }
 684 }
 685
 686 fn parse_arguments_to_quote(cx: &ExtCtxt, tts: &[ast::TokenTree])
 687                             -> (P<ast::Expr>, Vec<ast::TokenTree>) {
 688     // NB: It appears that the main parser loses its mind if we consider
 689     // $foo as a SubstNt during the main parse, so we have to re-parse
 690     // under quote_depth > 0. This is silly and should go away; the _guess_ is
 691     // it has to do with transition away from supporting old-style macros, so
 692     // try removing it when enough of them are gone.
 693
 694     let mut p = cx.new_parser_from_tts(tts);
 695     p.quote_depth += 1;
 696
 697     let cx_expr = p.parse_expr();
 698     if !panictry!(p.eat(&token::Comma)) {
 699         panic!(p.fatal("expected token `,`"));
 700     }
 701
 702     let tts = panictry!(p.parse_all_token_trees());
 703     p.abort_if_errors();
 704
 705     (cx_expr, tts)
 706 }
 707
 708 fn mk_stmts_let(cx: &ExtCtxt, sp: Span) -> Vec<P<ast::Stmt>> {
 709     // We also bind a single value, sp, to ext_cx.call_site()
 710     //
 711     // This causes every span in a token-tree quote to be attributed to the
 712     // call site of the extension using the quote. We can't really do much
 713     // better since the source of the quote may well be in a library that
 714     // was not even parsed by this compilation run, that the user has no
 715     // source code for (eg. in libsyntax, which they're just _using_).
 716     //
 717     // The old quasiquoter had an elaborate mechanism for denoting input
 718     // file locations from which quotes originated; unfortunately this
 719     // relied on feeding the source string of the quote back into the
 720     // compiler (which we don't really want to do) and, in any case, only
 721     // pushed the problem a very small step further back: an error
 722     // resulting from a parse of the resulting quote is still attributed to
 723     // the site the string literal occurred, which was in a source file
 724     // _other_ than the one the user has control over. For example, an
 725     // error in a quote from the protocol compiler, invoked in user code
 726     // using macro_rules! for example, will be attributed to the macro_rules.rs
 727     // file in libsyntax, which the user might not even have source to (unless
 728     // they happen to have a compiler on hand). Over all, the phase distinction
 729     // just makes quotes "hard to attribute". Possibly this could be fixed
 730     // by recreating some of the original qq machinery in the tt regime
 731     // (pushing fake FileMaps onto the parser to account for original sites
 732     // of quotes, for example) but at this point it seems not likely to be
 733     // worth the hassle.
 734
 735     let e_sp = cx.expr_method_call(sp,
 736                                    cx.expr_ident(sp, id_ext("ext_cx")),
 737                                    id_ext("call_site"),
 738                                    Vec::new());
 739
 740     let stmt_let_sp = cx.stmt_let(sp, false,
 741                                   id_ext("_sp"),
 742                                   e_sp);
 743
 744     let stmt_let_tt = cx.stmt_let(sp, true, id_ext("tt"), cx.expr_vec_ng(sp));
 745
 746     vec!(stmt_let_sp, stmt_let_tt)
 747 }
 748
 749 fn statements_mk_tts(cx: &ExtCtxt, tts: &[ast::TokenTree], matcher: bool) -> Vec<P<ast::Stmt>> {
 750     let mut ss = Vec::new();
 751     for tt in tts {
 752         ss.extend(statements_mk_tt(cx, tt, matcher));
 753     }
 754     ss
 755 }
 756
 757 fn expand_tts(cx: &ExtCtxt, sp: Span, tts: &[ast::TokenTree])
 758               -> (P<ast::Expr>, P<ast::Expr>) {
 759     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
 760
 761     let mut vector = mk_stmts_let(cx, sp);
 762     vector.extend(statements_mk_tts(cx, &tts[..], false));
 763     let block = cx.expr_block(
 764         cx.block_all(sp,
 765                      vector,
 766                      Some(cx.expr_ident(sp, id_ext("tt")))));
 767
 768     (cx_expr, block)
 769 }
 770
 771 fn expand_wrapper(cx: &ExtCtxt,
 772                   sp: Span,
 773                   cx_expr: P<ast::Expr>,
 774                   expr: P<ast::Expr>,
 775                   imports: &[&[&str]]) -> P<ast::Expr> {
 776     // Explicitly borrow to avoid moving from the invoker (#16992)
 777     let cx_expr_borrow = cx.expr_addr_of(sp, cx.expr_deref(sp, cx_expr));
 778     let stmt_let_ext_cx = cx.stmt_let(sp, false, id_ext("ext_cx"), cx_expr_borrow);
 779
 780     let stmts = imports.iter().map(|path| {
 781         // make item: `use ...;`
 782         let path = path.iter().map(|s| s.to_string()).collect();
 783         cx.stmt_item(sp, cx.item_use_glob(sp, ast::Inherited, ids_ext(path)))
 784     }).chain(Some(stmt_let_ext_cx)).collect();
 785
 786     cx.expr_block(cx.block_all(sp, stmts, Some(expr)))
 787 }
 788
 789 fn expand_parse_call(cx: &ExtCtxt,
 790                      sp: Span,
 791                      parse_method: &str,
 792                      arg_exprs: Vec<P<ast::Expr>> ,
 793                      tts: &[ast::TokenTree]) -> P<ast::Expr> {
 794     let (cx_expr, tts_expr) = expand_tts(cx, sp, tts);
 795
 796     let cfg_call = || cx.expr_method_call(
 797         sp, cx.expr_ident(sp, id_ext("ext_cx")),
 798         id_ext("cfg"), Vec::new());
 799
 800     let parse_sess_call = || cx.expr_method_call(
 801         sp, cx.expr_ident(sp, id_ext("ext_cx")),
 802         id_ext("parse_sess"), Vec::new());
 803
 804     let new_parser_call =
 805         cx.expr_call(sp,
 806                      cx.expr_ident(sp, id_ext("new_parser_from_tts")),
 807                      vec!(parse_sess_call(), cfg_call(), tts_expr));
 808
 809     let expr = cx.expr_method_call(sp, new_parser_call, id_ext(parse_method),
 810                                    arg_exprs);
 811
 812     if parse_method == "parse_attribute" {
 813         expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"],
 814                                                 &["syntax", "parse", "attr"]])
 815     } else {
 816         expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"]])
 817     }
 818 }