src/libsyntax/ext/base.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 pub use self::SyntaxExtension::*;
  12
  13 use ast::{self, Attribute, Name, PatKind, MetaItem};
  14 use attr::HasAttrs;
  15 use codemap::{self, CodeMap, Spanned, respan};
  16 use syntax_pos::{Span, MultiSpan, DUMMY_SP};
  17 use edition::Edition;
  18 use errors::{DiagnosticBuilder, DiagnosticId};
  19 use ext::expand::{self, Expansion, Invocation};
  20 use ext::hygiene::{self, Mark, SyntaxContext};
  21 use fold::{self, Folder};
  22 use parse::{self, parser, DirectoryOwnership};
  23 use parse::token;
  24 use ptr::P;
  25 use symbol::{keywords, Ident, Symbol};
  26 use util::small_vector::SmallVector;
  27
  28 use std::collections::HashMap;
  29 use std::iter;
  30 use std::path::PathBuf;
  31 use std::rc::Rc;
  32 use rustc_data_structures::sync::{self, Lrc};
  33 use std::default::Default;
  34 use tokenstream::{self, TokenStream};
  35
  36
  37 #[derive(Debug,Clone)]
  38 pub enum Annotatable {
  39     Item(P<ast::Item>),
  40     TraitItem(P<ast::TraitItem>),
  41     ImplItem(P<ast::ImplItem>),
  42     ForeignItem(P<ast::ForeignItem>),
  43     Stmt(P<ast::Stmt>),
  44     Expr(P<ast::Expr>),
  45 }
  46
  47 impl HasAttrs for Annotatable {
  48     fn attrs(&self) -> &[Attribute] {
  49         match *self {
  50             Annotatable::Item(ref item) => &item.attrs,
  51             Annotatable::TraitItem(ref trait_item) => &trait_item.attrs,
  52             Annotatable::ImplItem(ref impl_item) => &impl_item.attrs,
  53             Annotatable::ForeignItem(ref foreign_item) => &foreign_item.attrs,
  54             Annotatable::Stmt(ref stmt) => stmt.attrs(),
  55             Annotatable::Expr(ref expr) => &expr.attrs,
  56         }
  57     }
  58
  59     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
  60         match self {
  61             Annotatable::Item(item) => Annotatable::Item(item.map_attrs(f)),
  62             Annotatable::TraitItem(trait_item) => Annotatable::TraitItem(trait_item.map_attrs(f)),
  63             Annotatable::ImplItem(impl_item) => Annotatable::ImplItem(impl_item.map_attrs(f)),
  64             Annotatable::ForeignItem(foreign_item) =>
  65                 Annotatable::ForeignItem(foreign_item.map_attrs(f)),
  66             Annotatable::Stmt(stmt) => Annotatable::Stmt(stmt.map_attrs(f)),
  67             Annotatable::Expr(expr) => Annotatable::Expr(expr.map_attrs(f)),
  68         }
  69     }
  70 }
  71
  72 impl Annotatable {
  73     pub fn span(&self) -> Span {
  74         match *self {
  75             Annotatable::Item(ref item) => item.span,
  76             Annotatable::TraitItem(ref trait_item) => trait_item.span,
  77             Annotatable::ImplItem(ref impl_item) => impl_item.span,
  78             Annotatable::ForeignItem(ref foreign_item) => foreign_item.span,
  79             Annotatable::Stmt(ref stmt) => stmt.span,
  80             Annotatable::Expr(ref expr) => expr.span,
  81         }
  82     }
  83
  84     pub fn expect_item(self) -> P<ast::Item> {
  85         match self {
  86             Annotatable::Item(i) => i,
  87             _ => panic!("expected Item")
  88         }
  89     }
  90
  91     pub fn map_item_or<F, G>(self, mut f: F, mut or: G) -> Annotatable
  92         where F: FnMut(P<ast::Item>) -> P<ast::Item>,
  93               G: FnMut(Annotatable) -> Annotatable
  94     {
  95         match self {
  96             Annotatable::Item(i) => Annotatable::Item(f(i)),
  97             _ => or(self)
  98         }
  99     }
 100
 101     pub fn expect_trait_item(self) -> ast::TraitItem {
 102         match self {
 103             Annotatable::TraitItem(i) => i.into_inner(),
 104             _ => panic!("expected Item")
 105         }
 106     }
 107
 108     pub fn expect_impl_item(self) -> ast::ImplItem {
 109         match self {
 110             Annotatable::ImplItem(i) => i.into_inner(),
 111             _ => panic!("expected Item")
 112         }
 113     }
 114
 115     pub fn expect_foreign_item(self) -> ast::ForeignItem {
 116         match self {
 117             Annotatable::ForeignItem(i) => i.into_inner(),
 118             _ => panic!("expected foreign item")
 119         }
 120     }
 121
 122     pub fn expect_stmt(self) -> ast::Stmt {
 123         match self {
 124             Annotatable::Stmt(stmt) => stmt.into_inner(),
 125             _ => panic!("expected statement"),
 126         }
 127     }
 128
 129     pub fn expect_expr(self) -> P<ast::Expr> {
 130         match self {
 131             Annotatable::Expr(expr) => expr,
 132             _ => panic!("expected expression"),
 133         }
 134     }
 135
 136     pub fn derive_allowed(&self) -> bool {
 137         match *self {
 138             Annotatable::Item(ref item) => match item.node {
 139                 ast::ItemKind::Struct(..) |
 140                 ast::ItemKind::Enum(..) |
 141                 ast::ItemKind::Union(..) => true,
 142                 _ => false,
 143             },
 144             _ => false,
 145         }
 146     }
 147 }
 148
 149 // A more flexible ItemDecorator.
 150 pub trait MultiItemDecorator {
 151     fn expand(&self,
 152               ecx: &mut ExtCtxt,
 153               sp: Span,
 154               meta_item: &ast::MetaItem,
 155               item: &Annotatable,
 156               push: &mut FnMut(Annotatable));
 157 }
 158
 159 impl<F> MultiItemDecorator for F
 160     where F : Fn(&mut ExtCtxt, Span, &ast::MetaItem, &Annotatable, &mut FnMut(Annotatable))
 161 {
 162     fn expand(&self,
 163               ecx: &mut ExtCtxt,
 164               sp: Span,
 165               meta_item: &ast::MetaItem,
 166               item: &Annotatable,
 167               push: &mut FnMut(Annotatable)) {
 168         (*self)(ecx, sp, meta_item, item, push)
 169     }
 170 }
 171
 172 // `meta_item` is the annotation, and `item` is the item being modified.
 173 // FIXME Decorators should follow the same pattern too.
 174 pub trait MultiItemModifier {
 175     fn expand(&self,
 176               ecx: &mut ExtCtxt,
 177               span: Span,
 178               meta_item: &ast::MetaItem,
 179               item: Annotatable)
 180               -> Vec<Annotatable>;
 181 }
 182
 183 impl<F, T> MultiItemModifier for F
 184     where F: Fn(&mut ExtCtxt, Span, &ast::MetaItem, Annotatable) -> T,
 185           T: Into<Vec<Annotatable>>,
 186 {
 187     fn expand(&self,
 188               ecx: &mut ExtCtxt,
 189               span: Span,
 190               meta_item: &ast::MetaItem,
 191               item: Annotatable)
 192               -> Vec<Annotatable> {
 193         (*self)(ecx, span, meta_item, item).into()
 194     }
 195 }
 196
 197 impl Into<Vec<Annotatable>> for Annotatable {
 198     fn into(self) -> Vec<Annotatable> {
 199         vec![self]
 200     }
 201 }
 202
 203 pub trait ProcMacro {
 204     fn expand<'cx>(&self,
 205                    ecx: &'cx mut ExtCtxt,
 206                    span: Span,
 207                    ts: TokenStream)
 208                    -> TokenStream;
 209 }
 210
 211 impl<F> ProcMacro for F
 212     where F: Fn(TokenStream) -> TokenStream
 213 {
 214     fn expand<'cx>(&self,
 215                    _ecx: &'cx mut ExtCtxt,
 216                    _span: Span,
 217                    ts: TokenStream)
 218                    -> TokenStream {
 219         // FIXME setup implicit context in TLS before calling self.
 220         (*self)(ts)
 221     }
 222 }
 223
 224 pub trait AttrProcMacro {
 225     fn expand<'cx>(&self,
 226                    ecx: &'cx mut ExtCtxt,
 227                    span: Span,
 228                    annotation: TokenStream,
 229                    annotated: TokenStream)
 230                    -> TokenStream;
 231 }
 232
 233 impl<F> AttrProcMacro for F
 234     where F: Fn(TokenStream, TokenStream) -> TokenStream
 235 {
 236     fn expand<'cx>(&self,
 237                    _ecx: &'cx mut ExtCtxt,
 238                    _span: Span,
 239                    annotation: TokenStream,
 240                    annotated: TokenStream)
 241                    -> TokenStream {
 242         // FIXME setup implicit context in TLS before calling self.
 243         (*self)(annotation, annotated)
 244     }
 245 }
 246
 247 /// Represents a thing that maps token trees to Macro Results
 248 pub trait TTMacroExpander {
 249     fn expand<'cx>(&self, ecx: &'cx mut ExtCtxt, span: Span, input: TokenStream)
 250                    -> Box<MacResult+'cx>;
 251 }
 252
 253 pub type MacroExpanderFn =
 254     for<'cx> fn(&'cx mut ExtCtxt, Span, &[tokenstream::TokenTree])
 255                 -> Box<MacResult+'cx>;
 256
 257 impl<F> TTMacroExpander for F
 258     where F: for<'cx> Fn(&'cx mut ExtCtxt, Span, &[tokenstream::TokenTree]) -> Box<MacResult+'cx>
 259 {
 260     fn expand<'cx>(&self, ecx: &'cx mut ExtCtxt, span: Span, input: TokenStream)
 261                    -> Box<MacResult+'cx> {
 262         struct AvoidInterpolatedIdents;
 263
 264         impl Folder for AvoidInterpolatedIdents {
 265             fn fold_tt(&mut self, tt: tokenstream::TokenTree) -> tokenstream::TokenTree {
 266                 if let tokenstream::TokenTree::Token(_, token::Interpolated(ref nt)) = tt {
 267                     if let token::NtIdent(ident, is_raw) = nt.0 {
 268                         return tokenstream::TokenTree::Token(ident.span,
 269                                                              token::Ident(ident, is_raw));
 270                     }
 271                 }
 272                 fold::noop_fold_tt(tt, self)
 273             }
 274
 275             fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
 276                 fold::noop_fold_mac(mac, self)
 277             }
 278         }
 279
 280         let input: Vec<_> =
 281             input.trees().map(|tt| AvoidInterpolatedIdents.fold_tt(tt)).collect();
 282         (*self)(ecx, span, &input)
 283     }
 284 }
 285
 286 pub trait IdentMacroExpander {
 287     fn expand<'cx>(&self,
 288                    cx: &'cx mut ExtCtxt,
 289                    sp: Span,
 290                    ident: ast::Ident,
 291                    token_tree: Vec<tokenstream::TokenTree>)
 292                    -> Box<MacResult+'cx>;
 293 }
 294
 295 pub type IdentMacroExpanderFn =
 296     for<'cx> fn(&'cx mut ExtCtxt, Span, ast::Ident, Vec<tokenstream::TokenTree>)
 297                 -> Box<MacResult+'cx>;
 298
 299 impl<F> IdentMacroExpander for F
 300     where F : for<'cx> Fn(&'cx mut ExtCtxt, Span, ast::Ident,
 301                           Vec<tokenstream::TokenTree>) -> Box<MacResult+'cx>
 302 {
 303     fn expand<'cx>(&self,
 304                    cx: &'cx mut ExtCtxt,
 305                    sp: Span,
 306                    ident: ast::Ident,
 307                    token_tree: Vec<tokenstream::TokenTree>)
 308                    -> Box<MacResult+'cx>
 309     {
 310         (*self)(cx, sp, ident, token_tree)
 311     }
 312 }
 313
 314 // Use a macro because forwarding to a simple function has type system issues
 315 macro_rules! make_stmts_default {
 316     ($me:expr) => {
 317         $me.make_expr().map(|e| SmallVector::one(ast::Stmt {
 318             id: ast::DUMMY_NODE_ID,
 319             span: e.span,
 320             node: ast::StmtKind::Expr(e),
 321         }))
 322     }
 323 }
 324
 325 /// The result of a macro expansion. The return values of the various
 326 /// methods are spliced into the AST at the callsite of the macro.
 327 pub trait MacResult {
 328     /// Create an expression.
 329     fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
 330         None
 331     }
 332     /// Create zero or more items.
 333     fn make_items(self: Box<Self>) -> Option<SmallVector<P<ast::Item>>> {
 334         None
 335     }
 336
 337     /// Create zero or more impl items.
 338     fn make_impl_items(self: Box<Self>) -> Option<SmallVector<ast::ImplItem>> {
 339         None
 340     }
 341
 342     /// Create zero or more trait items.
 343     fn make_trait_items(self: Box<Self>) -> Option<SmallVector<ast::TraitItem>> {
 344         None
 345     }
 346
 347     /// Create zero or more items in an `extern {}` block
 348     fn make_foreign_items(self: Box<Self>) -> Option<SmallVector<ast::ForeignItem>> { None }
 349
 350     /// Create a pattern.
 351     fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
 352         None
 353     }
 354
 355     /// Create zero or more statements.
 356     ///
 357     /// By default this attempts to create an expression statement,
 358     /// returning None if that fails.
 359     fn make_stmts(self: Box<Self>) -> Option<SmallVector<ast::Stmt>> {
 360         make_stmts_default!(self)
 361     }
 362
 363     fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
 364         None
 365     }
 366 }
 367
 368 macro_rules! make_MacEager {
 369     ( $( $fld:ident: $t:ty, )* ) => {
 370         /// `MacResult` implementation for the common case where you've already
 371         /// built each form of AST that you might return.
 372         #[derive(Default)]
 373         pub struct MacEager {
 374             $(
 375                 pub $fld: Option<$t>,
 376             )*
 377         }
 378
 379         impl MacEager {
 380             $(
 381                 pub fn $fld(v: $t) -> Box<MacResult> {
 382                     Box::new(MacEager {
 383                         $fld: Some(v),
 384                         ..Default::default()
 385                     })
 386                 }
 387             )*
 388         }
 389     }
 390 }
 391
 392 make_MacEager! {
 393     expr: P<ast::Expr>,
 394     pat: P<ast::Pat>,
 395     items: SmallVector<P<ast::Item>>,
 396     impl_items: SmallVector<ast::ImplItem>,
 397     trait_items: SmallVector<ast::TraitItem>,
 398     foreign_items: SmallVector<ast::ForeignItem>,
 399     stmts: SmallVector<ast::Stmt>,
 400     ty: P<ast::Ty>,
 401 }
 402
 403 impl MacResult for MacEager {
 404     fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
 405         self.expr
 406     }
 407
 408     fn make_items(self: Box<Self>) -> Option<SmallVector<P<ast::Item>>> {
 409         self.items
 410     }
 411
 412     fn make_impl_items(self: Box<Self>) -> Option<SmallVector<ast::ImplItem>> {
 413         self.impl_items
 414     }
 415
 416     fn make_trait_items(self: Box<Self>) -> Option<SmallVector<ast::TraitItem>> {
 417         self.trait_items
 418     }
 419
 420     fn make_foreign_items(self: Box<Self>) -> Option<SmallVector<ast::ForeignItem>> {
 421         self.foreign_items
 422     }
 423
 424     fn make_stmts(self: Box<Self>) -> Option<SmallVector<ast::Stmt>> {
 425         match self.stmts.as_ref().map_or(0, |s| s.len()) {
 426             0 => make_stmts_default!(self),
 427             _ => self.stmts,
 428         }
 429     }
 430
 431     fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
 432         if let Some(p) = self.pat {
 433             return Some(p);
 434         }
 435         if let Some(e) = self.expr {
 436             if let ast::ExprKind::Lit(_) = e.node {
 437                 return Some(P(ast::Pat {
 438                     id: ast::DUMMY_NODE_ID,
 439                     span: e.span,
 440                     node: PatKind::Lit(e),
 441                 }));
 442             }
 443         }
 444         None
 445     }
 446
 447     fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
 448         self.ty
 449     }
 450 }
 451
 452 /// Fill-in macro expansion result, to allow compilation to continue
 453 /// after hitting errors.
 454 #[derive(Copy, Clone)]
 455 pub struct DummyResult {
 456     expr_only: bool,
 457     span: Span
 458 }
 459
 460 impl DummyResult {
 461     /// Create a default MacResult that can be anything.
 462     ///
 463     /// Use this as a return value after hitting any errors and
 464     /// calling `span_err`.
 465     pub fn any(sp: Span) -> Box<MacResult+'static> {
 466         Box::new(DummyResult { expr_only: false, span: sp })
 467     }
 468
 469     /// Create a default MacResult that can only be an expression.
 470     ///
 471     /// Use this for macros that must expand to an expression, so even
 472     /// if an error is encountered internally, the user will receive
 473     /// an error that they also used it in the wrong place.
 474     pub fn expr(sp: Span) -> Box<MacResult+'static> {
 475         Box::new(DummyResult { expr_only: true, span: sp })
 476     }
 477
 478     /// A plain dummy expression.
 479     pub fn raw_expr(sp: Span) -> P<ast::Expr> {
 480         P(ast::Expr {
 481             id: ast::DUMMY_NODE_ID,
 482             node: ast::ExprKind::Lit(P(codemap::respan(sp, ast::LitKind::Bool(false)))),
 483             span: sp,
 484             attrs: ast::ThinVec::new(),
 485         })
 486     }
 487
 488     /// A plain dummy pattern.
 489     pub fn raw_pat(sp: Span) -> ast::Pat {
 490         ast::Pat {
 491             id: ast::DUMMY_NODE_ID,
 492             node: PatKind::Wild,
 493             span: sp,
 494         }
 495     }
 496
 497     pub fn raw_ty(sp: Span) -> P<ast::Ty> {
 498         P(ast::Ty {
 499             id: ast::DUMMY_NODE_ID,
 500             node: ast::TyKind::Infer,
 501             span: sp
 502         })
 503     }
 504 }
 505
 506 impl MacResult for DummyResult {
 507     fn make_expr(self: Box<DummyResult>) -> Option<P<ast::Expr>> {
 508         Some(DummyResult::raw_expr(self.span))
 509     }
 510
 511     fn make_pat(self: Box<DummyResult>) -> Option<P<ast::Pat>> {
 512         Some(P(DummyResult::raw_pat(self.span)))
 513     }
 514
 515     fn make_items(self: Box<DummyResult>) -> Option<SmallVector<P<ast::Item>>> {
 516         // this code needs a comment... why not always just return the Some() ?
 517         if self.expr_only {
 518             None
 519         } else {
 520             Some(SmallVector::new())
 521         }
 522     }
 523
 524     fn make_impl_items(self: Box<DummyResult>) -> Option<SmallVector<ast::ImplItem>> {
 525         if self.expr_only {
 526             None
 527         } else {
 528             Some(SmallVector::new())
 529         }
 530     }
 531
 532     fn make_trait_items(self: Box<DummyResult>) -> Option<SmallVector<ast::TraitItem>> {
 533         if self.expr_only {
 534             None
 535         } else {
 536             Some(SmallVector::new())
 537         }
 538     }
 539
 540     fn make_foreign_items(self: Box<Self>) -> Option<SmallVector<ast::ForeignItem>> {
 541         if self.expr_only {
 542             None
 543         } else {
 544             Some(SmallVector::new())
 545         }
 546     }
 547
 548     fn make_stmts(self: Box<DummyResult>) -> Option<SmallVector<ast::Stmt>> {
 549         Some(SmallVector::one(ast::Stmt {
 550             id: ast::DUMMY_NODE_ID,
 551             node: ast::StmtKind::Expr(DummyResult::raw_expr(self.span)),
 552             span: self.span,
 553         }))
 554     }
 555
 556     fn make_ty(self: Box<DummyResult>) -> Option<P<ast::Ty>> {
 557         Some(DummyResult::raw_ty(self.span))
 558     }
 559 }
 560
 561 pub type BuiltinDeriveFn =
 562     for<'cx> fn(&'cx mut ExtCtxt, Span, &MetaItem, &Annotatable, &mut FnMut(Annotatable));
 563
 564 /// Represents different kinds of macro invocations that can be resolved.
 565 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 566 pub enum MacroKind {
 567     /// A bang macro - foo!()
 568     Bang,
 569     /// An attribute macro - #[foo]
 570     Attr,
 571     /// A derive attribute macro - #[derive(Foo)]
 572     Derive,
 573 }
 574
 575 impl MacroKind {
 576     pub fn descr(self) -> &'static str {
 577         match self {
 578             MacroKind::Bang => "macro",
 579             MacroKind::Attr => "attribute macro",
 580             MacroKind::Derive => "derive macro",
 581         }
 582     }
 583 }
 584
 585 /// An enum representing the different kinds of syntax extensions.
 586 pub enum SyntaxExtension {
 587     /// A syntax extension that is attached to an item and creates new items
 588     /// based upon it.
 589     ///
 590     /// `#[derive(...)]` is a `MultiItemDecorator`.
 591     ///
 592     /// Prefer ProcMacro or MultiModifier since they are more flexible.
 593     MultiDecorator(Box<MultiItemDecorator + sync::Sync + sync::Send>),
 594
 595     /// A syntax extension that is attached to an item and modifies it
 596     /// in-place. Also allows decoration, i.e., creating new items.
 597     MultiModifier(Box<MultiItemModifier + sync::Sync + sync::Send>),
 598
 599     /// A function-like procedural macro. TokenStream -> TokenStream.
 600     ProcMacro(Box<ProcMacro + sync::Sync + sync::Send>, Edition),
 601
 602     /// An attribute-like procedural macro. TokenStream, TokenStream -> TokenStream.
 603     /// The first TokenSteam is the attribute, the second is the annotated item.
 604     /// Allows modification of the input items and adding new items, similar to
 605     /// MultiModifier, but uses TokenStreams, rather than AST nodes.
 606     AttrProcMacro(Box<AttrProcMacro + sync::Sync + sync::Send>, Edition),
 607
 608     /// A normal, function-like syntax extension.
 609     ///
 610     /// `bytes!` is a `NormalTT`.
 611     NormalTT {
 612         expander: Box<TTMacroExpander + sync::Sync + sync::Send>,
 613         def_info: Option<(ast::NodeId, Span)>,
 614         /// Whether the contents of the macro can
 615         /// directly use `#[unstable]` things (true == yes).
 616         allow_internal_unstable: bool,
 617         /// Whether the contents of the macro can use `unsafe`
 618         /// without triggering the `unsafe_code` lint.
 619         allow_internal_unsafe: bool,
 620         /// The macro's feature name if it is unstable, and the stability feature
 621         unstable_feature: Option<(Symbol, u32)>,
 622         /// Edition of the crate in which the macro is defined
 623         edition: Edition,
 624     },
 625
 626     /// A function-like syntax extension that has an extra ident before
 627     /// the block.
 628     ///
 629     IdentTT(Box<IdentMacroExpander + sync::Sync + sync::Send>, Option<Span>, bool),
 630
 631     /// An attribute-like procedural macro. TokenStream -> TokenStream.
 632     /// The input is the annotated item.
 633     /// Allows generating code to implement a Trait for a given struct
 634     /// or enum item.
 635     ProcMacroDerive(Box<MultiItemModifier + sync::Sync + sync::Send>,
 636                     Vec<Symbol> /* inert attribute names */, Edition),
 637
 638     /// An attribute-like procedural macro that derives a builtin trait.
 639     BuiltinDerive(BuiltinDeriveFn),
 640
 641     /// A declarative macro, e.g. `macro m() {}`.
 642     ///
 643     /// The second element is the definition site span.
 644     DeclMacro(Box<TTMacroExpander + sync::Sync + sync::Send>, Option<(ast::NodeId, Span)>, Edition),
 645 }
 646
 647 impl SyntaxExtension {
 648     /// Return which kind of macro calls this syntax extension.
 649     pub fn kind(&self) -> MacroKind {
 650         match *self {
 651             SyntaxExtension::DeclMacro(..) |
 652             SyntaxExtension::NormalTT { .. } |
 653             SyntaxExtension::IdentTT(..) |
 654             SyntaxExtension::ProcMacro(..) =>
 655                 MacroKind::Bang,
 656             SyntaxExtension::MultiDecorator(..) |
 657             SyntaxExtension::MultiModifier(..) |
 658             SyntaxExtension::AttrProcMacro(..) =>
 659                 MacroKind::Attr,
 660             SyntaxExtension::ProcMacroDerive(..) |
 661             SyntaxExtension::BuiltinDerive(..) =>
 662                 MacroKind::Derive,
 663         }
 664     }
 665
 666     pub fn is_modern(&self) -> bool {
 667         match *self {
 668             SyntaxExtension::DeclMacro(..) |
 669             SyntaxExtension::ProcMacro(..) |
 670             SyntaxExtension::AttrProcMacro(..) |
 671             SyntaxExtension::ProcMacroDerive(..) => true,
 672             _ => false,
 673         }
 674     }
 675
 676     pub fn edition(&self) -> Edition {
 677         match *self {
 678             SyntaxExtension::NormalTT { edition, .. } |
 679             SyntaxExtension::DeclMacro(.., edition) |
 680             SyntaxExtension::ProcMacro(.., edition) |
 681             SyntaxExtension::AttrProcMacro(.., edition) |
 682             SyntaxExtension::ProcMacroDerive(.., edition) => edition,
 683             // Unstable legacy stuff
 684             SyntaxExtension::IdentTT(..) |
 685             SyntaxExtension::MultiDecorator(..) |
 686             SyntaxExtension::MultiModifier(..) |
 687             SyntaxExtension::BuiltinDerive(..) => hygiene::default_edition(),
 688         }
 689     }
 690 }
 691
 692 pub type NamedSyntaxExtension = (Name, SyntaxExtension);
 693
 694 pub trait Resolver {
 695     fn next_node_id(&mut self) -> ast::NodeId;
 696     fn get_module_scope(&mut self, id: ast::NodeId) -> Mark;
 697     fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item>;
 698     fn is_whitelisted_legacy_custom_derive(&self, name: Name) -> bool;
 699
 700     fn visit_expansion(&mut self, mark: Mark, expansion: &Expansion, derives: &[Mark]);
 701     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>);
 702
 703     fn resolve_imports(&mut self);
 704     // Resolves attribute and derive legacy macros from `#![plugin(..)]`.
 705     fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec<Attribute>, allow_derive: bool)
 706                               -> Option<Attribute>;
 707
 708     fn resolve_invoc(&mut self, invoc: &mut Invocation, scope: Mark, force: bool)
 709                      -> Result<Option<Lrc<SyntaxExtension>>, Determinacy>;
 710     fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, kind: MacroKind, force: bool)
 711                      -> Result<Lrc<SyntaxExtension>, Determinacy>;
 712     fn check_unused_macros(&self);
 713 }
 714
 715 #[derive(Copy, Clone, Debug, PartialEq)]
 716 pub enum Determinacy {
 717     Determined,
 718     Undetermined,
 719 }
 720
 721 pub struct DummyResolver;
 722
 723 impl Resolver for DummyResolver {
 724     fn next_node_id(&mut self) -> ast::NodeId { ast::DUMMY_NODE_ID }
 725     fn get_module_scope(&mut self, _id: ast::NodeId) -> Mark { Mark::root() }
 726     fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item> { item }
 727     fn is_whitelisted_legacy_custom_derive(&self, _name: Name) -> bool { false }
 728
 729     fn visit_expansion(&mut self, _invoc: Mark, _expansion: &Expansion, _derives: &[Mark]) {}
 730     fn add_builtin(&mut self, _ident: ast::Ident, _ext: Lrc<SyntaxExtension>) {}
 731
 732     fn resolve_imports(&mut self) {}
 733     fn find_legacy_attr_invoc(&mut self, _attrs: &mut Vec<Attribute>, _allow_derive: bool)
 734                               -> Option<Attribute> { None }
 735     fn resolve_invoc(&mut self, _invoc: &mut Invocation, _scope: Mark, _force: bool)
 736                      -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
 737         Err(Determinacy::Determined)
 738     }
 739     fn resolve_macro(&mut self, _scope: Mark, _path: &ast::Path, _kind: MacroKind,
 740                      _force: bool) -> Result<Lrc<SyntaxExtension>, Determinacy> {
 741         Err(Determinacy::Determined)
 742     }
 743     fn check_unused_macros(&self) {}
 744 }
 745
 746 #[derive(Clone)]
 747 pub struct ModuleData {
 748     pub mod_path: Vec<ast::Ident>,
 749     pub directory: PathBuf,
 750 }
 751
 752 #[derive(Clone)]
 753 pub struct ExpansionData {
 754     pub mark: Mark,
 755     pub depth: usize,
 756     pub module: Rc<ModuleData>,
 757     pub directory_ownership: DirectoryOwnership,
 758     pub crate_span: Option<Span>,
 759 }
 760
 761 /// One of these is made during expansion and incrementally updated as we go;
 762 /// when a macro expansion occurs, the resulting nodes have the `backtrace()
 763 /// -> expn_info` of their expansion context stored into their span.
 764 pub struct ExtCtxt<'a> {
 765     pub parse_sess: &'a parse::ParseSess,
 766     pub ecfg: expand::ExpansionConfig<'a>,
 767     pub root_path: PathBuf,
 768     pub resolver: &'a mut Resolver,
 769     pub resolve_err_count: usize,
 770     pub current_expansion: ExpansionData,
 771     pub expansions: HashMap<Span, Vec<String>>,
 772 }
 773
 774 impl<'a> ExtCtxt<'a> {
 775     pub fn new(parse_sess: &'a parse::ParseSess,
 776                ecfg: expand::ExpansionConfig<'a>,
 777                resolver: &'a mut Resolver)
 778                -> ExtCtxt<'a> {
 779         ExtCtxt {
 780             parse_sess,
 781             ecfg,
 782             root_path: PathBuf::new(),
 783             resolver,
 784             resolve_err_count: 0,
 785             current_expansion: ExpansionData {
 786                 mark: Mark::root(),
 787                 depth: 0,
 788                 module: Rc::new(ModuleData { mod_path: Vec::new(), directory: PathBuf::new() }),
 789                 directory_ownership: DirectoryOwnership::Owned { relative: None },
 790                 crate_span: None,
 791             },
 792             expansions: HashMap::new(),
 793         }
 794     }
 795
 796     /// Returns a `Folder` for deeply expanding all macros in an AST node.
 797     pub fn expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
 798         expand::MacroExpander::new(self, false)
 799     }
 800
 801     /// Returns a `Folder` that deeply expands all macros and assigns all node ids in an AST node.
 802     /// Once node ids are assigned, the node may not be expanded, removed, or otherwise modified.
 803     pub fn monotonic_expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
 804         expand::MacroExpander::new(self, true)
 805     }
 806
 807     pub fn new_parser_from_tts(&self, tts: &[tokenstream::TokenTree]) -> parser::Parser<'a> {
 808         parse::stream_to_parser(self.parse_sess, tts.iter().cloned().collect())
 809     }
 810     pub fn codemap(&self) -> &'a CodeMap { self.parse_sess.codemap() }
 811     pub fn parse_sess(&self) -> &'a parse::ParseSess { self.parse_sess }
 812     pub fn cfg(&self) -> &ast::CrateConfig { &self.parse_sess.config }
 813     pub fn call_site(&self) -> Span {
 814         match self.current_expansion.mark.expn_info() {
 815             Some(expn_info) => expn_info.call_site,
 816             None => DUMMY_SP,
 817         }
 818     }
 819     pub fn backtrace(&self) -> SyntaxContext {
 820         SyntaxContext::empty().apply_mark(self.current_expansion.mark)
 821     }
 822
 823     /// Returns span for the macro which originally caused the current expansion to happen.
 824     ///
 825     /// Stops backtracing at include! boundary.
 826     pub fn expansion_cause(&self) -> Option<Span> {
 827         let mut ctxt = self.backtrace();
 828         let mut last_macro = None;
 829         loop {
 830             if ctxt.outer().expn_info().map_or(None, |info| {
 831                 if info.callee.name() == "include" {
 832                     // Stop going up the backtrace once include! is encountered
 833                     return None;
 834                 }
 835                 ctxt = info.call_site.ctxt();
 836                 last_macro = Some(info.call_site);
 837                 Some(())
 838             }).is_none() {
 839                 break
 840             }
 841         }
 842         last_macro
 843     }
 844
 845     pub fn struct_span_warn<S: Into<MultiSpan>>(&self,
 846                                                 sp: S,
 847                                                 msg: &str)
 848                                                 -> DiagnosticBuilder<'a> {
 849         self.parse_sess.span_diagnostic.struct_span_warn(sp, msg)
 850     }
 851     pub fn struct_span_err<S: Into<MultiSpan>>(&self,
 852                                                sp: S,
 853                                                msg: &str)
 854                                                -> DiagnosticBuilder<'a> {
 855         self.parse_sess.span_diagnostic.struct_span_err(sp, msg)
 856     }
 857     pub fn struct_span_fatal<S: Into<MultiSpan>>(&self,
 858                                                  sp: S,
 859                                                  msg: &str)
 860                                                  -> DiagnosticBuilder<'a> {
 861         self.parse_sess.span_diagnostic.struct_span_fatal(sp, msg)
 862     }
 863
 864     /// Emit `msg` attached to `sp`, and stop compilation immediately.
 865     ///
 866     /// `span_err` should be strongly preferred where-ever possible:
 867     /// this should *only* be used when:
 868     ///
 869     /// - continuing has a high risk of flow-on errors (e.g. errors in
 870     ///   declaring a macro would cause all uses of that macro to
 871     ///   complain about "undefined macro"), or
 872     /// - there is literally nothing else that can be done (however,
 873     ///   in most cases one can construct a dummy expression/item to
 874     ///   substitute; we never hit resolve/type-checking so the dummy
 875     ///   value doesn't have to match anything)
 876     pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
 877         self.parse_sess.span_diagnostic.span_fatal(sp, msg).raise();
 878     }
 879
 880     /// Emit `msg` attached to `sp`, without immediately stopping
 881     /// compilation.
 882     ///
 883     /// Compilation will be stopped in the near future (at the end of
 884     /// the macro expansion phase).
 885     pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
 886         self.parse_sess.span_diagnostic.span_err(sp, msg);
 887     }
 888     pub fn span_err_with_code<S: Into<MultiSpan>>(&self, sp: S, msg: &str, code: DiagnosticId) {
 889         self.parse_sess.span_diagnostic.span_err_with_code(sp, msg, code);
 890     }
 891     pub fn mut_span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str)
 892                         -> DiagnosticBuilder<'a> {
 893         self.parse_sess.span_diagnostic.mut_span_err(sp, msg)
 894     }
 895     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
 896         self.parse_sess.span_diagnostic.span_warn(sp, msg);
 897     }
 898     pub fn span_unimpl<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
 899         self.parse_sess.span_diagnostic.span_unimpl(sp, msg);
 900     }
 901     pub fn span_bug<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
 902         self.parse_sess.span_diagnostic.span_bug(sp, msg);
 903     }
 904     pub fn trace_macros_diag(&mut self) {
 905         for (sp, notes) in self.expansions.iter() {
 906             let mut db = self.parse_sess.span_diagnostic.span_note_diag(*sp, "trace_macro");
 907             for note in notes {
 908                 db.note(note);
 909             }
 910             db.emit();
 911         }
 912         // Fixme: does this result in errors?
 913         self.expansions.clear();
 914     }
 915     pub fn bug(&self, msg: &str) -> ! {
 916         self.parse_sess.span_diagnostic.bug(msg);
 917     }
 918     pub fn trace_macros(&self) -> bool {
 919         self.ecfg.trace_mac
 920     }
 921     pub fn set_trace_macros(&mut self, x: bool) {
 922         self.ecfg.trace_mac = x
 923     }
 924     pub fn ident_of(&self, st: &str) -> ast::Ident {
 925         ast::Ident::from_str(st)
 926     }
 927     pub fn std_path(&self, components: &[&str]) -> Vec<ast::Ident> {
 928         let def_site = DUMMY_SP.apply_mark(self.current_expansion.mark);
 929         iter::once(Ident::new(keywords::DollarCrate.name(), def_site))
 930             .chain(components.iter().map(|s| self.ident_of(s)))
 931             .collect()
 932     }
 933     pub fn name_of(&self, st: &str) -> ast::Name {
 934         Symbol::intern(st)
 935     }
 936
 937     pub fn check_unused_macros(&self) {
 938         self.resolver.check_unused_macros();
 939     }
 940 }
 941
 942 /// Extract a string literal from the macro expanded version of `expr`,
 943 /// emitting `err_msg` if `expr` is not a string literal. This does not stop
 944 /// compilation on error, merely emits a non-fatal error and returns None.
 945 pub fn expr_to_spanned_string(cx: &mut ExtCtxt, expr: P<ast::Expr>, err_msg: &str)
 946                               -> Option<Spanned<(Symbol, ast::StrStyle)>> {
 947     // Update `expr.span`'s ctxt now in case expr is an `include!` macro invocation.
 948     let expr = expr.map(|mut expr| {
 949         expr.span = expr.span.apply_mark(cx.current_expansion.mark);
 950         expr
 951     });
 952
 953     // we want to be able to handle e.g. concat("foo", "bar")
 954     let expr = cx.expander().fold_expr(expr);
 955     match expr.node {
 956         ast::ExprKind::Lit(ref l) => match l.node {
 957             ast::LitKind::Str(s, style) => return Some(respan(expr.span, (s, style))),
 958             _ => cx.span_err(l.span, err_msg)
 959         },
 960         _ => cx.span_err(expr.span, err_msg)
 961     }
 962     None
 963 }
 964
 965 pub fn expr_to_string(cx: &mut ExtCtxt, expr: P<ast::Expr>, err_msg: &str)
 966                       -> Option<(Symbol, ast::StrStyle)> {
 967     expr_to_spanned_string(cx, expr, err_msg).map(|s| s.node)
 968 }
 969
 970 /// Non-fatally assert that `tts` is empty. Note that this function
 971 /// returns even when `tts` is non-empty, macros that *need* to stop
 972 /// compilation should call
 973 /// `cx.parse_sess.span_diagnostic.abort_if_errors()` (this should be
 974 /// done as rarely as possible).
 975 pub fn check_zero_tts(cx: &ExtCtxt,
 976                       sp: Span,
 977                       tts: &[tokenstream::TokenTree],
 978                       name: &str) {
 979     if !tts.is_empty() {
 980         cx.span_err(sp, &format!("{} takes no arguments", name));
 981     }
 982 }
 983
 984 /// Interpreting `tts` as a comma-separated sequence of expressions,
 985 /// expect exactly one string literal, or emit an error and return None.
 986 pub fn get_single_str_from_tts(cx: &mut ExtCtxt,
 987                                sp: Span,
 988                                tts: &[tokenstream::TokenTree],
 989                                name: &str)
 990                                -> Option<String> {
 991     let mut p = cx.new_parser_from_tts(tts);
 992     if p.token == token::Eof {
 993         cx.span_err(sp, &format!("{} takes 1 argument", name));
 994         return None
 995     }
 996     let ret = panictry!(p.parse_expr());
 997     let _ = p.eat(&token::Comma);
 998
 999     if p.token != token::Eof {
1000         cx.span_err(sp, &format!("{} takes 1 argument", name));
1001     }
1002     expr_to_string(cx, ret, "argument must be a string literal").map(|(s, _)| {
1003         s.to_string()
1004     })
1005 }
1006
1007 /// Extract comma-separated expressions from `tts`. If there is a
1008 /// parsing error, emit a non-fatal error and return None.
1009 pub fn get_exprs_from_tts(cx: &mut ExtCtxt,
1010                           sp: Span,
1011                           tts: &[tokenstream::TokenTree]) -> Option<Vec<P<ast::Expr>>> {
1012     let mut p = cx.new_parser_from_tts(tts);
1013     let mut es = Vec::new();
1014     while p.token != token::Eof {
1015         es.push(cx.expander().fold_expr(panictry!(p.parse_expr())));
1016         if p.eat(&token::Comma) {
1017             continue;
1018         }
1019         if p.token != token::Eof {
1020             cx.span_err(sp, "expected token: `,`");
1021             return None;
1022         }
1023     }
1024     Some(es)
1025 }