src/libsyntax/ext/expand.rs

   1 // Copyright 2012-2014 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, Block, Ident, PatKind, Path};
  12 use ast::{MacStmtStyle, StmtKind, ItemKind};
  13 use attr::{self, HasAttrs};
  14 use codemap::{ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
  15 use config::{is_test_or_bench, StripUnconfigured};
  16 use ext::base::*;
  17 use ext::derive::{add_derived_markers, collect_derives};
  18 use ext::hygiene::Mark;
  19 use ext::placeholders::{placeholder, PlaceholderExpander};
  20 use feature_gate::{self, Features, is_builtin_attr};
  21 use fold;
  22 use fold::*;
  23 use parse::{filemap_to_stream, ParseSess, DirectoryOwnership, PResult, token};
  24 use parse::parser::Parser;
  25 use print::pprust;
  26 use ptr::P;
  27 use std_inject;
  28 use symbol::Symbol;
  29 use symbol::keywords;
  30 use syntax_pos::{Span, ExpnId, DUMMY_SP};
  31 use tokenstream::TokenStream;
  32 use util::small_vector::SmallVector;
  33 use visit::Visitor;
  34
  35 use std::collections::HashMap;
  36 use std::mem;
  37 use std::path::PathBuf;
  38 use std::rc::Rc;
  39
  40 macro_rules! expansions {
  41     ($($kind:ident: $ty:ty [$($vec:ident, $ty_elt:ty)*], $kind_name:expr, .$make:ident,
  42             $(.$fold:ident)*  $(lift .$fold_elt:ident)*,
  43             $(.$visit:ident)*  $(lift .$visit_elt:ident)*;)*) => {
  44         #[derive(Copy, Clone, PartialEq, Eq)]
  45         pub enum ExpansionKind { OptExpr, $( $kind, )*  }
  46         pub enum Expansion { OptExpr(Option<P<ast::Expr>>), $( $kind($ty), )* }
  47
  48         impl ExpansionKind {
  49             pub fn name(self) -> &'static str {
  50                 match self {
  51                     ExpansionKind::OptExpr => "expression",
  52                     $( ExpansionKind::$kind => $kind_name, )*
  53                 }
  54             }
  55
  56             fn make_from<'a>(self, result: Box<MacResult + 'a>) -> Option<Expansion> {
  57                 match self {
  58                     ExpansionKind::OptExpr => result.make_expr().map(Some).map(Expansion::OptExpr),
  59                     $( ExpansionKind::$kind => result.$make().map(Expansion::$kind), )*
  60                 }
  61             }
  62         }
  63
  64         impl Expansion {
  65             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  66                 match self {
  67                     Expansion::OptExpr(expr) => expr,
  68                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  69                 }
  70             }
  71             $( pub fn $make(self) -> $ty {
  72                 match self {
  73                     Expansion::$kind(ast) => ast,
  74                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  75                 }
  76             } )*
  77
  78             pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
  79                 use self::Expansion::*;
  80                 match self {
  81                     OptExpr(expr) => OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
  82                     $($( $kind(ast) => $kind(folder.$fold(ast)), )*)*
  83                     $($( $kind(ast) => {
  84                         $kind(ast.into_iter().flat_map(|ast| folder.$fold_elt(ast)).collect())
  85                     }, )*)*
  86                 }
  87             }
  88
  89             pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
  90                 match *self {
  91                     Expansion::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
  92                     Expansion::OptExpr(None) => {}
  93                     $($( Expansion::$kind(ref ast) => visitor.$visit(ast), )*)*
  94                     $($( Expansion::$kind(ref ast) => for ast in &ast[..] {
  95                         visitor.$visit_elt(ast);
  96                     }, )*)*
  97                 }
  98             }
  99         }
 100
 101         impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
 102             fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 103                 self.expand(Expansion::OptExpr(Some(expr))).make_opt_expr()
 104             }
 105             $($(fn $fold(&mut self, node: $ty) -> $ty {
 106                 self.expand(Expansion::$kind(node)).$make()
 107             })*)*
 108             $($(fn $fold_elt(&mut self, node: $ty_elt) -> $ty {
 109                 self.expand(Expansion::$kind(SmallVector::one(node))).$make()
 110             })*)*
 111         }
 112
 113         impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
 114             $(fn $make(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>) -> Option<$ty> {
 115                 Some(self.make(ExpansionKind::$kind).$make())
 116             })*
 117         }
 118     }
 119 }
 120
 121 expansions! {
 122     Expr: P<ast::Expr> [], "expression", .make_expr, .fold_expr, .visit_expr;
 123     Pat: P<ast::Pat>   [], "pattern",    .make_pat,  .fold_pat,  .visit_pat;
 124     Ty: P<ast::Ty>     [], "type",       .make_ty,   .fold_ty,   .visit_ty;
 125     Stmts: SmallVector<ast::Stmt> [SmallVector, ast::Stmt],
 126         "statement",  .make_stmts,       lift .fold_stmt, lift .visit_stmt;
 127     Items: SmallVector<P<ast::Item>> [SmallVector, P<ast::Item>],
 128         "item",       .make_items,       lift .fold_item, lift .visit_item;
 129     TraitItems: SmallVector<ast::TraitItem> [SmallVector, ast::TraitItem],
 130         "trait item", .make_trait_items, lift .fold_trait_item, lift .visit_trait_item;
 131     ImplItems: SmallVector<ast::ImplItem> [SmallVector, ast::ImplItem],
 132         "impl item",  .make_impl_items,  lift .fold_impl_item,  lift .visit_impl_item;
 133 }
 134
 135 impl ExpansionKind {
 136     fn dummy(self, span: Span) -> Expansion {
 137         self.make_from(DummyResult::any(span)).unwrap()
 138     }
 139
 140     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I) -> Expansion {
 141         let items = items.into_iter();
 142         match self {
 143             ExpansionKind::Items =>
 144                 Expansion::Items(items.map(Annotatable::expect_item).collect()),
 145             ExpansionKind::ImplItems =>
 146                 Expansion::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
 147             ExpansionKind::TraitItems =>
 148                 Expansion::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
 149             _ => unreachable!(),
 150         }
 151     }
 152 }
 153
 154 pub struct Invocation {
 155     pub kind: InvocationKind,
 156     expansion_kind: ExpansionKind,
 157     pub expansion_data: ExpansionData,
 158 }
 159
 160 pub enum InvocationKind {
 161     Bang {
 162         mac: ast::Mac,
 163         ident: Option<Ident>,
 164         span: Span,
 165     },
 166     Attr {
 167         attr: Option<ast::Attribute>,
 168         traits: Vec<Path>,
 169         item: Annotatable,
 170     },
 171     Derive {
 172         path: Path,
 173         item: Annotatable,
 174     },
 175 }
 176
 177 impl Invocation {
 178     fn span(&self) -> Span {
 179         match self.kind {
 180             InvocationKind::Bang { span, .. } => span,
 181             InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
 182             InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
 183             InvocationKind::Derive { ref path, .. } => path.span,
 184         }
 185     }
 186 }
 187
 188 pub struct MacroExpander<'a, 'b:'a> {
 189     pub cx: &'a mut ExtCtxt<'b>,
 190     monotonic: bool, // c.f. `cx.monotonic_expander()`
 191 }
 192
 193 impl<'a, 'b> MacroExpander<'a, 'b> {
 194     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 195         MacroExpander { cx: cx, monotonic: monotonic }
 196     }
 197
 198     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 199         self.cx.crate_root = std_inject::injected_crate_name(&krate);
 200         let mut module = ModuleData {
 201             mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
 202             directory: PathBuf::from(self.cx.codemap().span_to_filename(krate.span)),
 203         };
 204         module.directory.pop();
 205         self.cx.current_expansion.module = Rc::new(module);
 206
 207         let krate_item = Expansion::Items(SmallVector::one(P(ast::Item {
 208             attrs: krate.attrs,
 209             span: krate.span,
 210             node: ast::ItemKind::Mod(krate.module),
 211             ident: keywords::Invalid.ident(),
 212             id: ast::DUMMY_NODE_ID,
 213             vis: ast::Visibility::Public,
 214         })));
 215
 216         match self.expand(krate_item).make_items().pop().unwrap().unwrap() {
 217             ast::Item { attrs, node: ast::ItemKind::Mod(module), .. } => {
 218                 krate.attrs = attrs;
 219                 krate.module = module;
 220             },
 221             _ => unreachable!(),
 222         };
 223
 224         krate
 225     }
 226
 227     // Fully expand all the invocations in `expansion`.
 228     fn expand(&mut self, expansion: Expansion) -> Expansion {
 229         let orig_expansion_data = self.cx.current_expansion.clone();
 230         self.cx.current_expansion.depth = 0;
 231
 232         let (expansion, mut invocations) = self.collect_invocations(expansion, &[]);
 233         self.resolve_imports();
 234         invocations.reverse();
 235
 236         let mut expansions = Vec::new();
 237         let mut derives = HashMap::new();
 238         let mut undetermined_invocations = Vec::new();
 239         let (mut progress, mut force) = (false, !self.monotonic);
 240         loop {
 241             let mut invoc = if let Some(invoc) = invocations.pop() {
 242                 invoc
 243             } else {
 244                 self.resolve_imports();
 245                 if undetermined_invocations.is_empty() { break }
 246                 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
 247                 force = !mem::replace(&mut progress, false);
 248                 continue
 249             };
 250
 251             let scope =
 252                 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
 253             let ext = match self.cx.resolver.resolve_invoc(&mut invoc, scope, force) {
 254                 Ok(ext) => Some(ext),
 255                 Err(Determinacy::Determined) => None,
 256                 Err(Determinacy::Undetermined) => {
 257                     undetermined_invocations.push(invoc);
 258                     continue
 259                 }
 260             };
 261
 262             progress = true;
 263             let ExpansionData { depth, mark, .. } = invoc.expansion_data;
 264             self.cx.current_expansion = invoc.expansion_data.clone();
 265
 266             self.cx.current_expansion.mark = scope;
 267             // FIXME(jseyfried): Refactor out the following logic
 268             let (expansion, new_invocations) = if let Some(ext) = ext {
 269                 if let Some(ext) = ext {
 270                     let expansion = self.expand_invoc(invoc, ext);
 271                     self.collect_invocations(expansion, &[])
 272                 } else if let InvocationKind::Attr { attr: None, traits, item } = invoc.kind {
 273                     let item = item
 274                         .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
 275                     let item_with_markers =
 276                         add_derived_markers(&mut self.cx, &traits, item.clone());
 277                     let derives = derives.entry(invoc.expansion_data.mark).or_insert_with(Vec::new);
 278
 279                     for path in &traits {
 280                         let mark = Mark::fresh();
 281                         derives.push(mark);
 282                         let item = match self.cx.resolver.resolve_macro(
 283                                 Mark::root(), path, MacroKind::Derive, false) {
 284                             Ok(ext) => match *ext {
 285                                 SyntaxExtension::BuiltinDerive(..) => item_with_markers.clone(),
 286                                 _ => item.clone(),
 287                             },
 288                             _ => item.clone(),
 289                         };
 290                         invocations.push(Invocation {
 291                             kind: InvocationKind::Derive { path: path.clone(), item: item },
 292                             expansion_kind: invoc.expansion_kind,
 293                             expansion_data: ExpansionData {
 294                                 mark: mark,
 295                                 ..invoc.expansion_data.clone()
 296                             },
 297                         });
 298                     }
 299                     let expansion = invoc.expansion_kind
 300                         .expect_from_annotatables(::std::iter::once(item_with_markers));
 301                     self.collect_invocations(expansion, derives)
 302                 } else {
 303                     unreachable!()
 304                 }
 305             } else {
 306                 self.collect_invocations(invoc.expansion_kind.dummy(invoc.span()), &[])
 307             };
 308
 309             if expansions.len() < depth {
 310                 expansions.push(Vec::new());
 311             }
 312             expansions[depth - 1].push((mark, expansion));
 313             if !self.cx.ecfg.single_step {
 314                 invocations.extend(new_invocations.into_iter().rev());
 315             }
 316         }
 317
 318         self.cx.current_expansion = orig_expansion_data;
 319
 320         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 321         while let Some(expansions) = expansions.pop() {
 322             for (mark, expansion) in expansions.into_iter().rev() {
 323                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
 324                 placeholder_expander.add(mark.as_placeholder_id(), expansion, derives);
 325             }
 326         }
 327
 328         expansion.fold_with(&mut placeholder_expander)
 329     }
 330
 331     fn resolve_imports(&mut self) {
 332         if self.monotonic {
 333             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 334             self.cx.resolver.resolve_imports();
 335             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 336         }
 337     }
 338
 339     fn collect_invocations(&mut self, expansion: Expansion, derives: &[Mark])
 340                            -> (Expansion, Vec<Invocation>) {
 341         let result = {
 342             let mut collector = InvocationCollector {
 343                 cfg: StripUnconfigured {
 344                     should_test: self.cx.ecfg.should_test,
 345                     sess: self.cx.parse_sess,
 346                     features: self.cx.ecfg.features,
 347                 },
 348                 cx: self.cx,
 349                 invocations: Vec::new(),
 350                 monotonic: self.monotonic,
 351             };
 352             (expansion.fold_with(&mut collector), collector.invocations)
 353         };
 354
 355         if self.monotonic {
 356             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 357             let mark = self.cx.current_expansion.mark;
 358             self.cx.resolver.visit_expansion(mark, &result.0, derives);
 359             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 360         }
 361
 362         result
 363     }
 364
 365     fn expand_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 366         match invoc.kind {
 367             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext),
 368             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext),
 369             InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext),
 370         }
 371     }
 372
 373     fn expand_attr_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 374         let Invocation { expansion_kind: kind, .. } = invoc;
 375         let (attr, item) = match invoc.kind {
 376             InvocationKind::Attr { attr, item, .. } => (attr.unwrap(), item),
 377             _ => unreachable!(),
 378         };
 379
 380         attr::mark_used(&attr);
 381         self.cx.bt_push(ExpnInfo {
 382             call_site: attr.span,
 383             callee: NameAndSpan {
 384                 format: MacroAttribute(Symbol::intern(&format!("{}", attr.path))),
 385                 span: Some(attr.span),
 386                 allow_internal_unstable: false,
 387             }
 388         });
 389
 390         match *ext {
 391             MultiModifier(ref mac) => {
 392                 let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
 393                 let item = mac.expand(self.cx, attr.span, &meta, item);
 394                 kind.expect_from_annotatables(item)
 395             }
 396             MultiDecorator(ref mac) => {
 397                 let mut items = Vec::new();
 398                 let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
 399                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
 400                 items.push(item);
 401                 kind.expect_from_annotatables(items)
 402             }
 403             SyntaxExtension::AttrProcMacro(ref mac) => {
 404                 let item_toks = stream_for_item(&item, &self.cx.parse_sess);
 405
 406                 let span = Span {
 407                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
 408                         call_site: attr.span,
 409                         callee: NameAndSpan {
 410                             format: MacroAttribute(Symbol::intern(&format!("{}", attr.path))),
 411                             span: None,
 412                             allow_internal_unstable: false,
 413                         },
 414                     }),
 415                     ..attr.span
 416                 };
 417
 418                 let tok_result = mac.expand(self.cx, attr.span, attr.tokens.clone(), item_toks);
 419                 self.parse_expansion(tok_result, kind, &attr.path, span)
 420             }
 421             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
 422                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
 423                 kind.dummy(attr.span)
 424             }
 425             _ => {
 426                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
 427                 self.cx.span_err(attr.span, &msg);
 428                 kind.dummy(attr.span)
 429             }
 430         }
 431     }
 432
 433     /// Expand a macro invocation. Returns the result of expansion.
 434     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 435         let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
 436         let (mac, ident, span) = match invoc.kind {
 437             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 438             _ => unreachable!(),
 439         };
 440         let path = &mac.node.path;
 441
 442         let ident = ident.unwrap_or(keywords::Invalid.ident());
 443         let marked_tts =
 444             noop_fold_tts(mac.node.stream(), &mut Marker { mark: mark, expn_id: None });
 445         let opt_expanded = match *ext {
 446             NormalTT(ref expandfun, exp_span, allow_internal_unstable) => {
 447                 if ident.name != keywords::Invalid.name() {
 448                     let msg =
 449                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 450                     self.cx.span_err(path.span, &msg);
 451                     return kind.dummy(span);
 452                 }
 453
 454                 self.cx.bt_push(ExpnInfo {
 455                     call_site: span,
 456                     callee: NameAndSpan {
 457                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 458                         span: exp_span,
 459                         allow_internal_unstable: allow_internal_unstable,
 460                     },
 461                 });
 462
 463                 kind.make_from(expandfun.expand(self.cx, span, marked_tts))
 464             }
 465
 466             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 467                 if ident.name == keywords::Invalid.name() {
 468                     self.cx.span_err(path.span,
 469                                     &format!("macro {}! expects an ident argument", path));
 470                     return kind.dummy(span);
 471                 };
 472
 473                 self.cx.bt_push(ExpnInfo {
 474                     call_site: span,
 475                     callee: NameAndSpan {
 476                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 477                         span: tt_span,
 478                         allow_internal_unstable: allow_internal_unstable,
 479                     }
 480                 });
 481
 482                 let input: Vec<_> = marked_tts.into_trees().collect();
 483                 kind.make_from(expander.expand(self.cx, span, ident, input))
 484             }
 485
 486             MultiDecorator(..) | MultiModifier(..) | SyntaxExtension::AttrProcMacro(..) => {
 487                 self.cx.span_err(path.span,
 488                                  &format!("`{}` can only be used in attributes", path));
 489                 return kind.dummy(span);
 490             }
 491
 492             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
 493                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
 494                 return kind.dummy(span);
 495             }
 496
 497             SyntaxExtension::ProcMacro(ref expandfun) => {
 498                 if ident.name != keywords::Invalid.name() {
 499                     let msg =
 500                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 501                     self.cx.span_err(path.span, &msg);
 502                     return kind.dummy(span);
 503                 }
 504
 505                 self.cx.bt_push(ExpnInfo {
 506                     call_site: span,
 507                     callee: NameAndSpan {
 508                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 509                         // FIXME procedural macros do not have proper span info
 510                         // yet, when they do, we should use it here.
 511                         span: None,
 512                         // FIXME probably want to follow macro_rules macros here.
 513                         allow_internal_unstable: false,
 514                     },
 515                 });
 516
 517                 let tok_result = expandfun.expand(self.cx, span, marked_tts);
 518                 Some(self.parse_expansion(tok_result, kind, path, span))
 519             }
 520         };
 521
 522         let expanded = if let Some(expanded) = opt_expanded {
 523             expanded
 524         } else {
 525             let msg = format!("non-{kind} macro in {kind} position: {name}",
 526                               name = path.segments[0].identifier.name, kind = kind.name());
 527             self.cx.span_err(path.span, &msg);
 528             return kind.dummy(span);
 529         };
 530
 531         expanded.fold_with(&mut Marker {
 532             mark: mark,
 533             expn_id: Some(self.cx.backtrace()),
 534         })
 535     }
 536
 537     /// Expand a derive invocation. Returns the result of expansion.
 538     fn expand_derive_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 539         let Invocation { expansion_kind: kind, .. } = invoc;
 540         let (path, item) = match invoc.kind {
 541             InvocationKind::Derive { path, item } => (path, item),
 542             _ => unreachable!(),
 543         };
 544
 545         let pretty_name = Symbol::intern(&format!("derive({})", path));
 546         let span = path.span;
 547         let attr = ast::Attribute {
 548             path: path, tokens: TokenStream::empty(), span: span,
 549             // irrelevant:
 550             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 551         };
 552
 553         self.cx.bt_push(ExpnInfo {
 554             call_site: span,
 555             callee: NameAndSpan {
 556                 format: MacroAttribute(pretty_name),
 557                 span: None,
 558                 allow_internal_unstable: false,
 559             }
 560         });
 561
 562         match *ext {
 563             SyntaxExtension::ProcMacroDerive(ref ext, _) => {
 564                 let span = Span {
 565                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
 566                         call_site: span,
 567                         callee: NameAndSpan {
 568                             format: MacroAttribute(pretty_name),
 569                             span: None,
 570                             allow_internal_unstable: false,
 571                         },
 572                     }),
 573                     ..span
 574                 };
 575                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 576                     name: keywords::Invalid.name(),
 577                     span: DUMMY_SP,
 578                     node: ast::MetaItemKind::Word,
 579                 };
 580                 return kind.expect_from_annotatables(ext.expand(self.cx, span, &dummy, item));
 581             }
 582             SyntaxExtension::BuiltinDerive(func) => {
 583                 let span = Span {
 584                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
 585                         call_site: span,
 586                         callee: NameAndSpan {
 587                             format: MacroAttribute(pretty_name),
 588                             span: None,
 589                             allow_internal_unstable: true,
 590                         },
 591                     }),
 592                     ..span
 593                 };
 594                 let mut items = Vec::new();
 595                 func(self.cx, span, &attr.meta().unwrap(), &item, &mut |a| items.push(a));
 596                 return kind.expect_from_annotatables(items);
 597             }
 598             _ => {
 599                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 600                 self.cx.span_err(span, &msg);
 601                 kind.dummy(span)
 602             }
 603         }
 604     }
 605
 606     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, path: &Path, span: Span)
 607                        -> Expansion {
 608         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 609         let expansion = match parser.parse_expansion(kind, false) {
 610             Ok(expansion) => expansion,
 611             Err(mut err) => {
 612                 err.emit();
 613                 return kind.dummy(span);
 614             }
 615         };
 616         parser.ensure_complete_parse(path, kind.name(), span);
 617         // FIXME better span info
 618         expansion.fold_with(&mut ChangeSpan { span: span })
 619     }
 620 }
 621
 622 impl<'a> Parser<'a> {
 623     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 624                            -> PResult<'a, Expansion> {
 625         Ok(match kind {
 626             ExpansionKind::Items => {
 627                 let mut items = SmallVector::new();
 628                 while let Some(item) = self.parse_item()? {
 629                     items.push(item);
 630                 }
 631                 Expansion::Items(items)
 632             }
 633             ExpansionKind::TraitItems => {
 634                 let mut items = SmallVector::new();
 635                 while self.token != token::Eof {
 636                     items.push(self.parse_trait_item()?);
 637                 }
 638                 Expansion::TraitItems(items)
 639             }
 640             ExpansionKind::ImplItems => {
 641                 let mut items = SmallVector::new();
 642                 while self.token != token::Eof {
 643                     items.push(self.parse_impl_item()?);
 644                 }
 645                 Expansion::ImplItems(items)
 646             }
 647             ExpansionKind::Stmts => {
 648                 let mut stmts = SmallVector::new();
 649                 while self.token != token::Eof &&
 650                       // won't make progress on a `}`
 651                       self.token != token::CloseDelim(token::Brace) {
 652                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 653                         stmts.push(stmt);
 654                     }
 655                 }
 656                 Expansion::Stmts(stmts)
 657             }
 658             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 659             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 660             ExpansionKind::Ty => Expansion::Ty(self.parse_ty_no_plus()?),
 661             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 662         })
 663     }
 664
 665     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
 666         if self.token != token::Eof {
 667             let msg = format!("macro expansion ignores token `{}` and any following",
 668                               self.this_token_to_string());
 669             let mut err = self.diagnostic().struct_span_err(self.span, &msg);
 670             let msg = format!("caused by the macro expansion here; the usage \
 671                                of `{}!` is likely invalid in {} context",
 672                                macro_path, kind_name);
 673             err.span_note(span, &msg).emit();
 674         }
 675     }
 676 }
 677
 678 struct InvocationCollector<'a, 'b: 'a> {
 679     cx: &'a mut ExtCtxt<'b>,
 680     cfg: StripUnconfigured<'a>,
 681     invocations: Vec<Invocation>,
 682     monotonic: bool,
 683 }
 684
 685 macro_rules! fully_configure {
 686     ($this:ident, $node:ident, $noop_fold:ident) => {
 687         match $noop_fold($node, &mut $this.cfg).pop() {
 688             Some(node) => node,
 689             None => return SmallVector::new(),
 690         }
 691     }
 692 }
 693
 694 impl<'a, 'b> InvocationCollector<'a, 'b> {
 695     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 696         let mark = Mark::fresh();
 697         self.invocations.push(Invocation {
 698             kind: kind,
 699             expansion_kind: expansion_kind,
 700             expansion_data: ExpansionData {
 701                 mark: mark,
 702                 depth: self.cx.current_expansion.depth + 1,
 703                 ..self.cx.current_expansion.clone()
 704             },
 705         });
 706         placeholder(expansion_kind, mark.as_placeholder_id())
 707     }
 708
 709     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {
 710         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
 711     }
 712
 713     fn collect_attr(&mut self,
 714                     attr: Option<ast::Attribute>,
 715                     traits: Vec<Path>,
 716                     item: Annotatable,
 717                     kind: ExpansionKind)
 718                     -> Expansion {
 719         if !traits.is_empty() &&
 720            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
 721             self.cx.span_err(traits[0].span, "`derive` can be only be applied to items");
 722             return kind.expect_from_annotatables(::std::iter::once(item));
 723         }
 724         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })
 725     }
 726
 727     // If `item` is an attr invocation, remove and return the macro attribute.
 728     fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<Path>, T)
 729         where T: HasAttrs,
 730     {
 731         let (mut attr, mut traits) = (None, Vec::new());
 732
 733         item = item.map_attrs(|mut attrs| {
 734             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs) {
 735                 attr = Some(legacy_attr_invoc);
 736                 return attrs;
 737             }
 738
 739             if self.cx.ecfg.proc_macro_enabled() {
 740                 attr = find_attr_invoc(&mut attrs);
 741             }
 742             traits = collect_derives(&mut self.cx, &mut attrs);
 743             attrs
 744         });
 745
 746         (attr, traits, item)
 747     }
 748
 749     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 750         self.cfg.configure(node)
 751     }
 752
 753     // Detect use of feature-gated or invalid attributes on macro invocations
 754     // since they will not be detected after macro expansion.
 755     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
 756         let codemap = &self.cx.parse_sess.codemap();
 757         let features = self.cx.ecfg.features.unwrap();
 758         for attr in attrs.iter() {
 759             feature_gate::check_attribute(&attr, &self.cx.parse_sess, codemap, features);
 760         }
 761     }
 762 }
 763
 764 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 765     for i in 0 .. attrs.len() {
 766         if !attr::is_known(&attrs[i]) && !is_builtin_attr(&attrs[i]) {
 767              return Some(attrs.remove(i));
 768         }
 769     }
 770
 771     None
 772 }
 773
 774 // These are pretty nasty. Ideally, we would keep the tokens around, linked from
 775 // the AST. However, we don't so we need to create new ones. Since the item might
 776 // have come from a macro expansion (possibly only in part), we can't use the
 777 // existing codemap.
 778 //
 779 // Therefore, we must use the pretty printer (yuck) to turn the AST node into a
 780 // string, which we then re-tokenise (double yuck), but first we have to patch
 781 // the pretty-printed string on to the end of the existing codemap (infinity-yuck).
 782 fn stream_for_item(item: &Annotatable, parse_sess: &ParseSess) -> TokenStream {
 783     let text = match *item {
 784         Annotatable::Item(ref i) => pprust::item_to_string(i),
 785         Annotatable::TraitItem(ref ti) => pprust::trait_item_to_string(ti),
 786         Annotatable::ImplItem(ref ii) => pprust::impl_item_to_string(ii),
 787     };
 788     string_to_stream(text, parse_sess)
 789 }
 790
 791 fn string_to_stream(text: String, parse_sess: &ParseSess) -> TokenStream {
 792     let filename = String::from("<macro expansion>");
 793     filemap_to_stream(parse_sess, parse_sess.codemap().new_filemap(filename, None, text))
 794 }
 795
 796 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 797     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 798         let mut expr = self.cfg.configure_expr(expr).unwrap();
 799         expr.node = self.cfg.configure_expr_kind(expr.node);
 800
 801         if let ast::ExprKind::Mac(mac) = expr.node {
 802             self.check_attributes(&expr.attrs);
 803             self.collect_bang(mac, expr.span, ExpansionKind::Expr).make_expr()
 804         } else {
 805             P(noop_fold_expr(expr, self))
 806         }
 807     }
 808
 809     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 810         let mut expr = configure!(self, expr).unwrap();
 811         expr.node = self.cfg.configure_expr_kind(expr.node);
 812
 813         if let ast::ExprKind::Mac(mac) = expr.node {
 814             self.check_attributes(&expr.attrs);
 815             self.collect_bang(mac, expr.span, ExpansionKind::OptExpr).make_opt_expr()
 816         } else {
 817             Some(P(noop_fold_expr(expr, self)))
 818         }
 819     }
 820
 821     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 822         let pat = self.cfg.configure_pat(pat);
 823         match pat.node {
 824             PatKind::Mac(_) => {}
 825             _ => return noop_fold_pat(pat, self),
 826         }
 827
 828         pat.and_then(|pat| match pat.node {
 829             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, ExpansionKind::Pat).make_pat(),
 830             _ => unreachable!(),
 831         })
 832     }
 833
 834     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 835         let stmt = match self.cfg.configure_stmt(stmt) {
 836             Some(stmt) => stmt,
 837             None => return SmallVector::new(),
 838         };
 839
 840         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 841             mac.unwrap()
 842         } else {
 843             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 844             let ast::Stmt { id, node, span } = stmt;
 845             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 846                 ast::Stmt { id: id, node: node, span: span }
 847             }).collect()
 848         };
 849
 850         self.check_attributes(&attrs);
 851         let mut placeholder = self.collect_bang(mac, stmt.span, ExpansionKind::Stmts).make_stmts();
 852
 853         // If this is a macro invocation with a semicolon, then apply that
 854         // semicolon to the final statement produced by expansion.
 855         if style == MacStmtStyle::Semicolon {
 856             if let Some(stmt) = placeholder.pop() {
 857                 placeholder.push(stmt.add_trailing_semicolon());
 858             }
 859         }
 860
 861         placeholder
 862     }
 863
 864     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 865         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
 866         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
 867         let result = noop_fold_block(block, self);
 868         self.cx.current_expansion.directory_ownership = old_directory_ownership;
 869         result
 870     }
 871
 872     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 873         let item = configure!(self, item);
 874
 875         let (attr, traits, mut item) = self.classify_item(item);
 876         if attr.is_some() || !traits.is_empty() {
 877             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 878             return self.collect_attr(attr, traits, item, ExpansionKind::Items).make_items();
 879         }
 880
 881         match item.node {
 882             ast::ItemKind::Mac(..) => {
 883                 self.check_attributes(&item.attrs);
 884                 item.and_then(|item| match item.node {
 885                     ItemKind::Mac(mac) => {
 886                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 887                             mac: mac,
 888                             ident: Some(item.ident),
 889                             span: item.span,
 890                         }).make_items()
 891                     }
 892                     _ => unreachable!(),
 893                 })
 894             }
 895             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 896                 if item.ident == keywords::Invalid.ident() {
 897                     return noop_fold_item(item, self);
 898                 }
 899
 900                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
 901                 let mut module = (*self.cx.current_expansion.module).clone();
 902                 module.mod_path.push(item.ident);
 903
 904                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 905                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 906                 // Thus, if `inner` is the dummy span, we know the module is inline.
 907                 let inline_module = item.span.contains(inner) || inner == DUMMY_SP;
 908
 909                 if inline_module {
 910                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 911                         self.cx.current_expansion.directory_ownership = DirectoryOwnership::Owned;
 912                         module.directory.push(&*path.as_str());
 913                     } else {
 914                         module.directory.push(&*item.ident.name.as_str());
 915                     }
 916                 } else {
 917                     let mut path =
 918                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 919                     let directory_ownership = match path.file_name().unwrap().to_str() {
 920                         Some("mod.rs") => DirectoryOwnership::Owned,
 921                         _ => DirectoryOwnership::UnownedViaMod(false),
 922                     };
 923                     path.pop();
 924                     module.directory = path;
 925                     self.cx.current_expansion.directory_ownership = directory_ownership;
 926                 }
 927
 928                 let orig_module =
 929                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 930                 let result = noop_fold_item(item, self);
 931                 self.cx.current_expansion.module = orig_module;
 932                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
 933                 return result;
 934             }
 935             // Ensure that test functions are accessible from the test harness.
 936             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 937                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 938                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 939                 }
 940                 noop_fold_item(item, self)
 941             }
 942             _ => noop_fold_item(item, self),
 943         }
 944     }
 945
 946     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 947         let item = configure!(self, item);
 948
 949         let (attr, traits, item) = self.classify_item(item);
 950         if attr.is_some() || !traits.is_empty() {
 951             let item =
 952                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 953             return self.collect_attr(attr, traits, item, ExpansionKind::TraitItems)
 954                 .make_trait_items()
 955         }
 956
 957         match item.node {
 958             ast::TraitItemKind::Macro(mac) => {
 959                 let ast::TraitItem { attrs, span, .. } = item;
 960                 self.check_attributes(&attrs);
 961                 self.collect_bang(mac, span, ExpansionKind::TraitItems).make_trait_items()
 962             }
 963             _ => fold::noop_fold_trait_item(item, self),
 964         }
 965     }
 966
 967     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 968         let item = configure!(self, item);
 969
 970         let (attr, traits, item) = self.classify_item(item);
 971         if attr.is_some() || !traits.is_empty() {
 972             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 973             return self.collect_attr(attr, traits, item, ExpansionKind::ImplItems)
 974                 .make_impl_items();
 975         }
 976
 977         match item.node {
 978             ast::ImplItemKind::Macro(mac) => {
 979                 let ast::ImplItem { attrs, span, .. } = item;
 980                 self.check_attributes(&attrs);
 981                 self.collect_bang(mac, span, ExpansionKind::ImplItems).make_impl_items()
 982             }
 983             _ => fold::noop_fold_impl_item(item, self),
 984         }
 985     }
 986
 987     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
 988         let ty = match ty.node {
 989             ast::TyKind::Mac(_) => ty.unwrap(),
 990             _ => return fold::noop_fold_ty(ty, self),
 991         };
 992
 993         match ty.node {
 994             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, ExpansionKind::Ty).make_ty(),
 995             _ => unreachable!(),
 996         }
 997     }
 998
 999     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1000         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1001     }
1002
1003     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1004         match item {
1005             ast::ItemKind::MacroDef(..) => item,
1006             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1007         }
1008     }
1009
1010     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1011         if self.monotonic {
1012             assert_eq!(id, ast::DUMMY_NODE_ID);
1013             self.cx.resolver.next_node_id()
1014         } else {
1015             id
1016         }
1017     }
1018 }
1019
1020 pub struct ExpansionConfig<'feat> {
1021     pub crate_name: String,
1022     pub features: Option<&'feat Features>,
1023     pub recursion_limit: usize,
1024     pub trace_mac: bool,
1025     pub should_test: bool, // If false, strip `#[test]` nodes
1026     pub single_step: bool,
1027     pub keep_macs: bool,
1028 }
1029
1030 macro_rules! feature_tests {
1031     ($( fn $getter:ident = $field:ident, )*) => {
1032         $(
1033             pub fn $getter(&self) -> bool {
1034                 match self.features {
1035                     Some(&Features { $field: true, .. }) => true,
1036                     _ => false,
1037                 }
1038             }
1039         )*
1040     }
1041 }
1042
1043 impl<'feat> ExpansionConfig<'feat> {
1044     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1045         ExpansionConfig {
1046             crate_name: crate_name,
1047             features: None,
1048             recursion_limit: 64,
1049             trace_mac: false,
1050             should_test: false,
1051             single_step: false,
1052             keep_macs: false,
1053         }
1054     }
1055
1056     feature_tests! {
1057         fn enable_quotes = quote,
1058         fn enable_asm = asm,
1059         fn enable_log_syntax = log_syntax,
1060         fn enable_concat_idents = concat_idents,
1061         fn enable_trace_macros = trace_macros,
1062         fn enable_allow_internal_unstable = allow_internal_unstable,
1063         fn enable_custom_derive = custom_derive,
1064         fn proc_macro_enabled = proc_macro,
1065     }
1066 }
1067
1068 // A Marker adds the given mark to the syntax context and
1069 // sets spans' `expn_id` to the given expn_id (unless it is `None`).
1070 struct Marker { mark: Mark, expn_id: Option<ExpnId> }
1071
1072 impl Folder for Marker {
1073     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
1074         ident.ctxt = ident.ctxt.apply_mark(self.mark);
1075         ident
1076     }
1077     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1078         noop_fold_mac(mac, self)
1079     }
1080
1081     fn new_span(&mut self, mut span: Span) -> Span {
1082         if let Some(expn_id) = self.expn_id {
1083             span.expn_id = expn_id;
1084         }
1085         span
1086     }
1087 }