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, TokenTree};
  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![TokenTree::Token(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![TokenTree::Token(DUMMY_SP,
  81                                   token::Interpolated(token::NtPath(Box::new(self.clone()))))]
  82         }
  83     }
  84
  85     impl ToTokens for ast::Ty {
  86         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  87             vec![TokenTree::Token(self.span, token::Interpolated(token::NtTy(P(self.clone()))))]
  88         }
  89     }
  90
  91     impl ToTokens for ast::Block {
  92         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  93             vec![TokenTree::Token(self.span, token::Interpolated(token::NtBlock(P(self.clone()))))]
  94         }
  95     }
  96
  97     impl ToTokens for ast::Generics {
  98         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
  99             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(token::NtGenerics(self.clone())))]
 100         }
 101     }
 102
 103     impl ToTokens for ast::WhereClause {
 104         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 105             vec![TokenTree::Token(DUMMY_SP,
 106                                   token::Interpolated(token::NtWhereClause(self.clone())))]
 107         }
 108     }
 109
 110     impl ToTokens for P<ast::Item> {
 111         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 112             vec![TokenTree::Token(self.span, token::Interpolated(token::NtItem(self.clone())))]
 113         }
 114     }
 115
 116     impl ToTokens for P<ast::ImplItem> {
 117         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 118             vec![TokenTree::Token(self.span, token::Interpolated(token::NtImplItem(self.clone())))]
 119         }
 120     }
 121
 122     impl ToTokens for P<ast::TraitItem> {
 123         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 124             vec![TokenTree::Token(self.span, token::Interpolated(token::NtTraitItem(self.clone())))]
 125         }
 126     }
 127
 128     impl ToTokens for P<ast::Stmt> {
 129         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 130             let mut tts = vec![
 131                 TokenTree::Token(self.span, token::Interpolated(token::NtStmt(self.clone())))
 132             ];
 133
 134             // Some statements require a trailing semicolon.
 135             if classify::stmt_ends_with_semi(&self.node) {
 136                 tts.push(TokenTree::Token(self.span, token::Semi));
 137             }
 138
 139             tts
 140         }
 141     }
 142
 143     impl ToTokens for P<ast::Expr> {
 144         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 145             vec![TokenTree::Token(self.span, token::Interpolated(token::NtExpr(self.clone())))]
 146         }
 147     }
 148
 149     impl ToTokens for P<ast::Pat> {
 150         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 151             vec![TokenTree::Token(self.span, token::Interpolated(token::NtPat(self.clone())))]
 152         }
 153     }
 154
 155     impl ToTokens for ast::Arm {
 156         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 157             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(token::NtArm(self.clone())))]
 158         }
 159     }
 160
 161     macro_rules! impl_to_tokens_slice {
 162         ($t: ty, $sep: expr) => {
 163             impl ToTokens for [$t] {
 164                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 165                     let mut v = vec![];
 166                     for (i, x) in self.iter().enumerate() {
 167                         if i > 0 {
 168                             v.push_all(&$sep);
 169                         }
 170                         v.extend(x.to_tokens(cx));
 171                     }
 172                     v
 173                 }
 174             }
 175         };
 176     }
 177
 178     impl_to_tokens_slice! { ast::Ty, [TokenTree::Token(DUMMY_SP, token::Comma)] }
 179     impl_to_tokens_slice! { P<ast::Item>, [] }
 180
 181     impl ToTokens for P<ast::MetaItem> {
 182         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 183             vec![TokenTree::Token(DUMMY_SP, token::Interpolated(token::NtMeta(self.clone())))]
 184         }
 185     }
 186
 187     impl ToTokens for ast::Attribute {
 188         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 189             let mut r = vec![];
 190             // FIXME: The spans could be better
 191             r.push(TokenTree::Token(self.span, token::Pound));
 192             if self.node.style == ast::AttrStyle::Inner {
 193                 r.push(TokenTree::Token(self.span, token::Not));
 194             }
 195             r.push(TokenTree::Delimited(self.span, Rc::new(ast::Delimited {
 196                 delim: token::Bracket,
 197                 open_span: self.span,
 198                 tts: self.node.value.to_tokens(cx),
 199                 close_span: self.span,
 200             })));
 201             r
 202         }
 203     }
 204
 205     impl ToTokens for str {
 206         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 207             let lit = ast::LitStr(
 208                 token::intern_and_get_ident(self), ast::CookedStr);
 209             dummy_spanned(lit).to_tokens(cx)
 210         }
 211     }
 212
 213     impl ToTokens for () {
 214         fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
 215             vec![TokenTree::Delimited(DUMMY_SP, Rc::new(ast::Delimited {
 216                 delim: token::Paren,
 217                 open_span: DUMMY_SP,
 218                 tts: vec![],
 219                 close_span: DUMMY_SP,
 220             }))]
 221         }
 222     }
 223
 224     impl ToTokens for ast::Lit {
 225         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 226             // FIXME: This is wrong
 227             P(ast::Expr {
 228                 id: ast::DUMMY_NODE_ID,
 229                 node: ast::ExprLit(P(self.clone())),
 230                 span: DUMMY_SP,
 231             }).to_tokens(cx)
 232         }
 233     }
 234
 235     impl ToTokens for bool {
 236         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 237             dummy_spanned(ast::LitBool(*self)).to_tokens(cx)
 238         }
 239     }
 240
 241     impl ToTokens for char {
 242         fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 243             dummy_spanned(ast::LitChar(*self)).to_tokens(cx)
 244         }
 245     }
 246
 247     macro_rules! impl_to_tokens_int {
 248         (signed, $t:ty, $tag:expr) => (
 249             impl ToTokens for $t {
 250                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 251                     let lit = ast::LitInt(*self as u64, ast::SignedIntLit($tag,
 252                                                                           ast::Sign::new(*self)));
 253                     dummy_spanned(lit).to_tokens(cx)
 254                 }
 255             }
 256         );
 257         (unsigned, $t:ty, $tag:expr) => (
 258             impl ToTokens for $t {
 259                 fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
 260                     let lit = ast::LitInt(*self as u64, ast::UnsignedIntLit($tag));
 261                     dummy_spanned(lit).to_tokens(cx)
 262                 }
 263             }
 264         );
 265     }
 266
 267     impl_to_tokens_int! { signed, isize, ast::TyIs }
 268     impl_to_tokens_int! { signed, i8,  ast::TyI8 }
 269     impl_to_tokens_int! { signed, i16, ast::TyI16 }
 270     impl_to_tokens_int! { signed, i32, ast::TyI32 }
 271     impl_to_tokens_int! { signed, i64, ast::TyI64 }
 272
 273     impl_to_tokens_int! { unsigned, usize, ast::TyUs }
 274     impl_to_tokens_int! { unsigned, u8,   ast::TyU8 }
 275     impl_to_tokens_int! { unsigned, u16,  ast::TyU16 }
 276     impl_to_tokens_int! { unsigned, u32,  ast::TyU32 }
 277     impl_to_tokens_int! { unsigned, u64,  ast::TyU64 }
 278
 279     pub trait ExtParseUtils {
 280         fn parse_item(&self, s: String) -> P<ast::Item>;
 281         fn parse_expr(&self, s: String) -> P<ast::Expr>;
 282         fn parse_stmt(&self, s: String) -> P<ast::Stmt>;
 283         fn parse_tts(&self, s: String) -> Vec<TokenTree>;
 284     }
 285
 286     impl<'a> ExtParseUtils for ExtCtxt<'a> {
 287
 288         fn parse_item(&self, s: String) -> P<ast::Item> {
 289             parse::parse_item_from_source_str(
 290                 "<quote expansion>".to_string(),
 291                 s,
 292                 self.cfg(),
 293                 self.parse_sess()).expect("parse error")
 294         }
 295
 296         fn parse_stmt(&self, s: String) -> P<ast::Stmt> {
 297             parse::parse_stmt_from_source_str("<quote expansion>".to_string(),
 298                                               s,
 299                                               self.cfg(),
 300                                               self.parse_sess()).expect("parse error")
 301         }
 302
 303         fn parse_expr(&self, s: String) -> P<ast::Expr> {
 304             parse::parse_expr_from_source_str("<quote expansion>".to_string(),
 305                                               s,
 306                                               self.cfg(),
 307                                               self.parse_sess())
 308         }
 309
 310         fn parse_tts(&self, s: String) -> Vec<TokenTree> {
 311             parse::parse_tts_from_source_str("<quote expansion>".to_string(),
 312                                              s,
 313                                              self.cfg(),
 314                                              self.parse_sess())
 315         }
 316     }
 317 }
 318
 319 pub fn expand_quote_tokens<'cx>(cx: &'cx mut ExtCtxt,
 320                                 sp: Span,
 321                                 tts: &[TokenTree])
 322                                 -> Box<base::MacResult+'cx> {
 323     let (cx_expr, expr) = expand_tts(cx, sp, tts);
 324     let expanded = expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"]]);
 325     base::MacEager::expr(expanded)
 326 }
 327
 328 pub fn expand_quote_expr<'cx>(cx: &'cx mut ExtCtxt,
 329                               sp: Span,
 330                               tts: &[TokenTree])
 331                               -> Box<base::MacResult+'cx> {
 332     let expanded = expand_parse_call(cx, sp, "parse_expr_panic", vec!(), tts);
 333     base::MacEager::expr(expanded)
 334 }
 335
 336 pub fn expand_quote_item<'cx>(cx: &mut ExtCtxt,
 337                               sp: Span,
 338                               tts: &[TokenTree])
 339                               -> Box<base::MacResult+'cx> {
 340     let expanded = expand_parse_call(cx, sp, "parse_item_panic", vec!(), tts);
 341     base::MacEager::expr(expanded)
 342 }
 343
 344 pub fn expand_quote_pat<'cx>(cx: &'cx mut ExtCtxt,
 345                              sp: Span,
 346                              tts: &[TokenTree])
 347                              -> Box<base::MacResult+'cx> {
 348     let expanded = expand_parse_call(cx, sp, "parse_pat_panic", vec!(), tts);
 349     base::MacEager::expr(expanded)
 350 }
 351
 352 pub fn expand_quote_arm(cx: &mut ExtCtxt,
 353                         sp: Span,
 354                         tts: &[TokenTree])
 355                         -> Box<base::MacResult+'static> {
 356     let expanded = expand_parse_call(cx, sp, "parse_arm_panic", vec!(), tts);
 357     base::MacEager::expr(expanded)
 358 }
 359
 360 pub fn expand_quote_ty(cx: &mut ExtCtxt,
 361                        sp: Span,
 362                        tts: &[TokenTree])
 363                        -> Box<base::MacResult+'static> {
 364     let expanded = expand_parse_call(cx, sp, "parse_ty_panic", vec!(), tts);
 365     base::MacEager::expr(expanded)
 366 }
 367
 368 pub fn expand_quote_stmt(cx: &mut ExtCtxt,
 369                          sp: Span,
 370                          tts: &[TokenTree])
 371                          -> Box<base::MacResult+'static> {
 372     let expanded = expand_parse_call(cx, sp, "parse_stmt_panic", vec!(), tts);
 373     base::MacEager::expr(expanded)
 374 }
 375
 376 pub fn expand_quote_attr(cx: &mut ExtCtxt,
 377                          sp: Span,
 378                          tts: &[TokenTree])
 379                          -> Box<base::MacResult+'static> {
 380     let expanded = expand_parse_call(cx, sp, "parse_attribute_panic",
 381                                     vec!(cx.expr_bool(sp, true)), tts);
 382
 383     base::MacEager::expr(expanded)
 384 }
 385
 386 pub fn expand_quote_matcher(cx: &mut ExtCtxt,
 387                             sp: Span,
 388                             tts: &[TokenTree])
 389                             -> Box<base::MacResult+'static> {
 390     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
 391     let mut vector = mk_stmts_let(cx, sp);
 392     vector.extend(statements_mk_tts(cx, &tts[..], true));
 393     let block = cx.expr_block(
 394         cx.block_all(sp,
 395                      vector,
 396                      Some(cx.expr_ident(sp, id_ext("tt")))));
 397
 398     let expanded = expand_wrapper(cx, sp, cx_expr, block, &[&["syntax", "ext", "quote", "rt"]]);
 399     base::MacEager::expr(expanded)
 400 }
 401
 402 fn ids_ext(strs: Vec<String> ) -> Vec<ast::Ident> {
 403     strs.iter().map(|str| str_to_ident(&(*str))).collect()
 404 }
 405
 406 fn id_ext(str: &str) -> ast::Ident {
 407     str_to_ident(str)
 408 }
 409
 410 // Lift an ident to the expr that evaluates to that ident.
 411 fn mk_ident(cx: &ExtCtxt, sp: Span, ident: ast::Ident) -> P<ast::Expr> {
 412     let e_str = cx.expr_str(sp, ident.name.as_str());
 413     cx.expr_method_call(sp,
 414                         cx.expr_ident(sp, id_ext("ext_cx")),
 415                         id_ext("ident_of"),
 416                         vec!(e_str))
 417 }
 418
 419 // Lift a name to the expr that evaluates to that name
 420 fn mk_name(cx: &ExtCtxt, sp: Span, ident: ast::Ident) -> P<ast::Expr> {
 421     let e_str = cx.expr_str(sp, ident.name.as_str());
 422     cx.expr_method_call(sp,
 423                         cx.expr_ident(sp, id_ext("ext_cx")),
 424                         id_ext("name_of"),
 425                         vec!(e_str))
 426 }
 427
 428 fn mk_tt_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 429     let idents = vec!(id_ext("syntax"), id_ext("ast"), id_ext("TokenTree"), id_ext(name));
 430     cx.expr_path(cx.path_global(sp, idents))
 431 }
 432
 433 fn mk_ast_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 434     let idents = vec!(id_ext("syntax"), id_ext("ast"), id_ext(name));
 435     cx.expr_path(cx.path_global(sp, idents))
 436 }
 437
 438 fn mk_token_path(cx: &ExtCtxt, sp: Span, name: &str) -> P<ast::Expr> {
 439     let idents = vec!(id_ext("syntax"), id_ext("parse"), id_ext("token"), id_ext(name));
 440     cx.expr_path(cx.path_global(sp, idents))
 441 }
 442
 443 fn mk_binop(cx: &ExtCtxt, sp: Span, bop: token::BinOpToken) -> P<ast::Expr> {
 444     let name = match bop {
 445         token::Plus     => "Plus",
 446         token::Minus    => "Minus",
 447         token::Star     => "Star",
 448         token::Slash    => "Slash",
 449         token::Percent  => "Percent",
 450         token::Caret    => "Caret",
 451         token::And      => "And",
 452         token::Or       => "Or",
 453         token::Shl      => "Shl",
 454         token::Shr      => "Shr"
 455     };
 456     mk_token_path(cx, sp, name)
 457 }
 458
 459 fn mk_delim(cx: &ExtCtxt, sp: Span, delim: token::DelimToken) -> P<ast::Expr> {
 460     let name = match delim {
 461         token::Paren     => "Paren",
 462         token::Bracket   => "Bracket",
 463         token::Brace     => "Brace",
 464     };
 465     mk_token_path(cx, sp, name)
 466 }
 467
 468 #[allow(non_upper_case_globals)]
 469 fn expr_mk_token(cx: &ExtCtxt, sp: Span, tok: &token::Token) -> P<ast::Expr> {
 470     macro_rules! mk_lit {
 471         ($name: expr, $suffix: expr, $($args: expr),*) => {{
 472             let inner = cx.expr_call(sp, mk_token_path(cx, sp, $name), vec![$($args),*]);
 473             let suffix = match $suffix {
 474                 Some(name) => cx.expr_some(sp, mk_name(cx, sp, ast::Ident::with_empty_ctxt(name))),
 475                 None => cx.expr_none(sp)
 476             };
 477             cx.expr_call(sp, mk_token_path(cx, sp, "Literal"), vec![inner, suffix])
 478         }}
 479     }
 480     match *tok {
 481         token::BinOp(binop) => {
 482             return cx.expr_call(sp, mk_token_path(cx, sp, "BinOp"), vec!(mk_binop(cx, sp, binop)));
 483         }
 484         token::BinOpEq(binop) => {
 485             return cx.expr_call(sp, mk_token_path(cx, sp, "BinOpEq"),
 486                                 vec!(mk_binop(cx, sp, binop)));
 487         }
 488
 489         token::OpenDelim(delim) => {
 490             return cx.expr_call(sp, mk_token_path(cx, sp, "OpenDelim"),
 491                                 vec![mk_delim(cx, sp, delim)]);
 492         }
 493         token::CloseDelim(delim) => {
 494             return cx.expr_call(sp, mk_token_path(cx, sp, "CloseDelim"),
 495                                 vec![mk_delim(cx, sp, delim)]);
 496         }
 497
 498         token::Literal(token::Byte(i), suf) => {
 499             let e_byte = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 500             return mk_lit!("Byte", suf, e_byte);
 501         }
 502
 503         token::Literal(token::Char(i), suf) => {
 504             let e_char = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 505             return mk_lit!("Char", suf, e_char);
 506         }
 507
 508         token::Literal(token::Integer(i), suf) => {
 509             let e_int = mk_name(cx, sp, ast::Ident::with_empty_ctxt(i));
 510             return mk_lit!("Integer", suf, e_int);
 511         }
 512
 513         token::Literal(token::Float(fident), suf) => {
 514             let e_fident = mk_name(cx, sp, ast::Ident::with_empty_ctxt(fident));
 515             return mk_lit!("Float", suf, e_fident);
 516         }
 517
 518         token::Literal(token::Str_(ident), suf) => {
 519             return mk_lit!("Str_", suf, mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident)))
 520         }
 521
 522         token::Literal(token::StrRaw(ident, n), suf) => {
 523             return mk_lit!("StrRaw", suf, mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident)),
 524                            cx.expr_usize(sp, n))
 525         }
 526
 527         token::Ident(ident, style) => {
 528             return cx.expr_call(sp,
 529                                 mk_token_path(cx, sp, "Ident"),
 530                                 vec![mk_ident(cx, sp, ident),
 531                                      match style {
 532                                         ModName => mk_token_path(cx, sp, "ModName"),
 533                                         Plain   => mk_token_path(cx, sp, "Plain"),
 534                                      }]);
 535         }
 536
 537         token::Lifetime(ident) => {
 538             return cx.expr_call(sp,
 539                                 mk_token_path(cx, sp, "Lifetime"),
 540                                 vec!(mk_ident(cx, sp, ident)));
 541         }
 542
 543         token::DocComment(ident) => {
 544             return cx.expr_call(sp,
 545                                 mk_token_path(cx, sp, "DocComment"),
 546                                 vec!(mk_name(cx, sp, ast::Ident::with_empty_ctxt(ident))));
 547         }
 548
 549         token::MatchNt(name, kind, namep, kindp) => {
 550             return cx.expr_call(sp,
 551                                 mk_token_path(cx, sp, "MatchNt"),
 552                                 vec!(mk_ident(cx, sp, name),
 553                                      mk_ident(cx, sp, kind),
 554                                      match namep {
 555                                         ModName => mk_token_path(cx, sp, "ModName"),
 556                                         Plain   => mk_token_path(cx, sp, "Plain"),
 557                                      },
 558                                      match kindp {
 559                                         ModName => mk_token_path(cx, sp, "ModName"),
 560                                         Plain   => mk_token_path(cx, sp, "Plain"),
 561                                      }));
 562         }
 563
 564         token::Interpolated(_) => panic!("quote! with interpolated token"),
 565
 566         _ => ()
 567     }
 568
 569     let name = match *tok {
 570         token::Eq           => "Eq",
 571         token::Lt           => "Lt",
 572         token::Le           => "Le",
 573         token::EqEq         => "EqEq",
 574         token::Ne           => "Ne",
 575         token::Ge           => "Ge",
 576         token::Gt           => "Gt",
 577         token::AndAnd       => "AndAnd",
 578         token::OrOr         => "OrOr",
 579         token::Not          => "Not",
 580         token::Tilde        => "Tilde",
 581         token::At           => "At",
 582         token::Dot          => "Dot",
 583         token::DotDot       => "DotDot",
 584         token::Comma        => "Comma",
 585         token::Semi         => "Semi",
 586         token::Colon        => "Colon",
 587         token::ModSep       => "ModSep",
 588         token::RArrow       => "RArrow",
 589         token::LArrow       => "LArrow",
 590         token::FatArrow     => "FatArrow",
 591         token::Pound        => "Pound",
 592         token::Dollar       => "Dollar",
 593         token::Question     => "Question",
 594         token::Underscore   => "Underscore",
 595         token::Eof          => "Eof",
 596         _                   => panic!("unhandled token in quote!"),
 597     };
 598     mk_token_path(cx, sp, name)
 599 }
 600
 601 fn statements_mk_tt(cx: &ExtCtxt, tt: &TokenTree, matcher: bool) -> Vec<P<ast::Stmt>> {
 602     match *tt {
 603         TokenTree::Token(sp, SubstNt(ident, _)) => {
 604             // tt.extend($ident.to_tokens(ext_cx))
 605
 606             let e_to_toks =
 607                 cx.expr_method_call(sp,
 608                                     cx.expr_ident(sp, ident),
 609                                     id_ext("to_tokens"),
 610                                     vec!(cx.expr_ident(sp, id_ext("ext_cx"))));
 611             let e_to_toks =
 612                 cx.expr_method_call(sp, e_to_toks, id_ext("into_iter"), vec![]);
 613
 614             let e_push =
 615                 cx.expr_method_call(sp,
 616                                     cx.expr_ident(sp, id_ext("tt")),
 617                                     id_ext("extend"),
 618                                     vec!(e_to_toks));
 619
 620             vec!(cx.stmt_expr(e_push))
 621         }
 622         ref tt @ TokenTree::Token(_, MatchNt(..)) if !matcher => {
 623             let mut seq = vec![];
 624             for i in 0..tt.len() {
 625                 seq.push(tt.get_tt(i));
 626             }
 627             statements_mk_tts(cx, &seq[..], matcher)
 628         }
 629         TokenTree::Token(sp, ref tok) => {
 630             let e_sp = cx.expr_ident(sp, id_ext("_sp"));
 631             let e_tok = cx.expr_call(sp,
 632                                      mk_tt_path(cx, sp, "Token"),
 633                                      vec!(e_sp, expr_mk_token(cx, sp, tok)));
 634             let e_push =
 635                 cx.expr_method_call(sp,
 636                                     cx.expr_ident(sp, id_ext("tt")),
 637                                     id_ext("push"),
 638                                     vec!(e_tok));
 639             vec!(cx.stmt_expr(e_push))
 640         },
 641         TokenTree::Delimited(_, ref delimed) => {
 642             statements_mk_tt(cx, &delimed.open_tt(), matcher).into_iter()
 643                 .chain(delimed.tts.iter()
 644                                   .flat_map(|tt| statements_mk_tt(cx, tt, matcher)))
 645                 .chain(statements_mk_tt(cx, &delimed.close_tt(), matcher))
 646                 .collect()
 647         },
 648         TokenTree::Sequence(sp, ref seq) => {
 649             if !matcher {
 650                 panic!("TokenTree::Sequence in quote!");
 651             }
 652
 653             let e_sp = cx.expr_ident(sp, id_ext("_sp"));
 654
 655             let stmt_let_tt = cx.stmt_let(sp, true, id_ext("tt"), cx.expr_vec_ng(sp));
 656             let mut tts_stmts = vec![stmt_let_tt];
 657             tts_stmts.extend(statements_mk_tts(cx, &seq.tts[..], matcher));
 658             let e_tts = cx.expr_block(cx.block(sp, tts_stmts,
 659                                                    Some(cx.expr_ident(sp, id_ext("tt")))));
 660             let e_separator = match seq.separator {
 661                 Some(ref sep) => cx.expr_some(sp, expr_mk_token(cx, sp, sep)),
 662                 None => cx.expr_none(sp),
 663             };
 664             let e_op = match seq.op {
 665                 ast::ZeroOrMore => mk_ast_path(cx, sp, "ZeroOrMore"),
 666                 ast::OneOrMore => mk_ast_path(cx, sp, "OneOrMore"),
 667             };
 668             let fields = vec![cx.field_imm(sp, id_ext("tts"), e_tts),
 669                               cx.field_imm(sp, id_ext("separator"), e_separator),
 670                               cx.field_imm(sp, id_ext("op"), e_op),
 671                               cx.field_imm(sp, id_ext("num_captures"),
 672                                                cx.expr_usize(sp, seq.num_captures))];
 673             let seq_path = vec![id_ext("syntax"), id_ext("ast"), id_ext("SequenceRepetition")];
 674             let e_seq_struct = cx.expr_struct(sp, cx.path_global(sp, seq_path), fields);
 675             let e_rc_new = cx.expr_call_global(sp, vec![id_ext("std"),
 676                                                         id_ext("rc"),
 677                                                         id_ext("Rc"),
 678                                                         id_ext("new")],
 679                                                    vec![e_seq_struct]);
 680             let e_tok = cx.expr_call(sp,
 681                                      mk_tt_path(cx, sp, "Sequence"),
 682                                      vec!(e_sp, e_rc_new));
 683             let e_push =
 684                 cx.expr_method_call(sp,
 685                                     cx.expr_ident(sp, id_ext("tt")),
 686                                     id_ext("push"),
 687                                     vec!(e_tok));
 688             vec!(cx.stmt_expr(e_push))
 689         }
 690     }
 691 }
 692
 693 fn parse_arguments_to_quote(cx: &ExtCtxt, tts: &[TokenTree])
 694                             -> (P<ast::Expr>, Vec<TokenTree>) {
 695     // NB: It appears that the main parser loses its mind if we consider
 696     // $foo as a SubstNt during the main parse, so we have to re-parse
 697     // under quote_depth > 0. This is silly and should go away; the _guess_ is
 698     // it has to do with transition away from supporting old-style macros, so
 699     // try removing it when enough of them are gone.
 700
 701     let mut p = cx.new_parser_from_tts(tts);
 702     p.quote_depth += 1;
 703
 704     let cx_expr = panictry!(p.parse_expr_nopanic());
 705     if !panictry!(p.eat(&token::Comma)) {
 706         panic!(p.fatal("expected token `,`"));
 707     }
 708
 709     let tts = panictry!(p.parse_all_token_trees());
 710     p.abort_if_errors();
 711
 712     (cx_expr, tts)
 713 }
 714
 715 fn mk_stmts_let(cx: &ExtCtxt, sp: Span) -> Vec<P<ast::Stmt>> {
 716     // We also bind a single value, sp, to ext_cx.call_site()
 717     //
 718     // This causes every span in a token-tree quote to be attributed to the
 719     // call site of the extension using the quote. We can't really do much
 720     // better since the source of the quote may well be in a library that
 721     // was not even parsed by this compilation run, that the user has no
 722     // source code for (eg. in libsyntax, which they're just _using_).
 723     //
 724     // The old quasiquoter had an elaborate mechanism for denoting input
 725     // file locations from which quotes originated; unfortunately this
 726     // relied on feeding the source string of the quote back into the
 727     // compiler (which we don't really want to do) and, in any case, only
 728     // pushed the problem a very small step further back: an error
 729     // resulting from a parse of the resulting quote is still attributed to
 730     // the site the string literal occurred, which was in a source file
 731     // _other_ than the one the user has control over. For example, an
 732     // error in a quote from the protocol compiler, invoked in user code
 733     // using macro_rules! for example, will be attributed to the macro_rules.rs
 734     // file in libsyntax, which the user might not even have source to (unless
 735     // they happen to have a compiler on hand). Over all, the phase distinction
 736     // just makes quotes "hard to attribute". Possibly this could be fixed
 737     // by recreating some of the original qq machinery in the tt regime
 738     // (pushing fake FileMaps onto the parser to account for original sites
 739     // of quotes, for example) but at this point it seems not likely to be
 740     // worth the hassle.
 741
 742     let e_sp = cx.expr_method_call(sp,
 743                                    cx.expr_ident(sp, id_ext("ext_cx")),
 744                                    id_ext("call_site"),
 745                                    Vec::new());
 746
 747     let stmt_let_sp = cx.stmt_let(sp, false,
 748                                   id_ext("_sp"),
 749                                   e_sp);
 750
 751     let stmt_let_tt = cx.stmt_let(sp, true, id_ext("tt"), cx.expr_vec_ng(sp));
 752
 753     vec!(stmt_let_sp, stmt_let_tt)
 754 }
 755
 756 fn statements_mk_tts(cx: &ExtCtxt, tts: &[TokenTree], matcher: bool) -> Vec<P<ast::Stmt>> {
 757     let mut ss = Vec::new();
 758     for tt in tts {
 759         ss.extend(statements_mk_tt(cx, tt, matcher));
 760     }
 761     ss
 762 }
 763
 764 fn expand_tts(cx: &ExtCtxt, sp: Span, tts: &[TokenTree])
 765               -> (P<ast::Expr>, P<ast::Expr>) {
 766     let (cx_expr, tts) = parse_arguments_to_quote(cx, tts);
 767
 768     let mut vector = mk_stmts_let(cx, sp);
 769     vector.extend(statements_mk_tts(cx, &tts[..], false));
 770     let block = cx.expr_block(
 771         cx.block_all(sp,
 772                      vector,
 773                      Some(cx.expr_ident(sp, id_ext("tt")))));
 774
 775     (cx_expr, block)
 776 }
 777
 778 fn expand_wrapper(cx: &ExtCtxt,
 779                   sp: Span,
 780                   cx_expr: P<ast::Expr>,
 781                   expr: P<ast::Expr>,
 782                   imports: &[&[&str]]) -> P<ast::Expr> {
 783     // Explicitly borrow to avoid moving from the invoker (#16992)
 784     let cx_expr_borrow = cx.expr_addr_of(sp, cx.expr_deref(sp, cx_expr));
 785     let stmt_let_ext_cx = cx.stmt_let(sp, false, id_ext("ext_cx"), cx_expr_borrow);
 786
 787     let stmts = imports.iter().map(|path| {
 788         // make item: `use ...;`
 789         let path = path.iter().map(|s| s.to_string()).collect();
 790         cx.stmt_item(sp, cx.item_use_glob(sp, ast::Inherited, ids_ext(path)))
 791     }).chain(Some(stmt_let_ext_cx)).collect();
 792
 793     cx.expr_block(cx.block_all(sp, stmts, Some(expr)))
 794 }
 795
 796 fn expand_parse_call(cx: &ExtCtxt,
 797                      sp: Span,
 798                      parse_method: &str,
 799                      arg_exprs: Vec<P<ast::Expr>> ,
 800                      tts: &[TokenTree]) -> P<ast::Expr> {
 801     let (cx_expr, tts_expr) = expand_tts(cx, sp, tts);
 802
 803     let cfg_call = || cx.expr_method_call(
 804         sp, cx.expr_ident(sp, id_ext("ext_cx")),
 805         id_ext("cfg"), Vec::new());
 806
 807     let parse_sess_call = || cx.expr_method_call(
 808         sp, cx.expr_ident(sp, id_ext("ext_cx")),
 809         id_ext("parse_sess"), Vec::new());
 810
 811     let new_parser_call =
 812         cx.expr_call(sp,
 813                      cx.expr_ident(sp, id_ext("new_parser_from_tts")),
 814                      vec!(parse_sess_call(), cfg_call(), tts_expr));
 815
 816     let expr = cx.expr_method_call(sp, new_parser_call, id_ext(parse_method),
 817                                    arg_exprs);
 818
 819     if parse_method == "parse_attribute" {
 820         expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"],
 821                                                 &["syntax", "parse", "attr"]])
 822     } else {
 823         expand_wrapper(cx, sp, cx_expr, expr, &[&["syntax", "ext", "quote", "rt"]])
 824     }
 825 }