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::{Block, Ident, Mac_, PatKind};
  12 use ast::{Name, MacStmtStyle, StmtKind, ItemKind};
  13 use ast;
  14 use ext::hygiene::Mark;
  15 use ext::placeholders::{placeholder, PlaceholderExpander};
  16 use attr::{self, HasAttrs};
  17 use codemap::{ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
  18 use syntax_pos::{self, Span, ExpnId};
  19 use config::{is_test_or_bench, StripUnconfigured};
  20 use ext::base::*;
  21 use feature_gate::{self, Features};
  22 use fold;
  23 use fold::*;
  24 use parse::{ParseSess, PResult, lexer};
  25 use parse::parser::Parser;
  26 use parse::token::{self, intern, keywords};
  27 use print::pprust;
  28 use ptr::P;
  29 use std_inject;
  30 use tokenstream::{TokenTree, TokenStream};
  31 use util::small_vector::SmallVector;
  32 use visit::Visitor;
  33
  34 use std::mem;
  35 use std::path::PathBuf;
  36 use std::rc::Rc;
  37
  38 macro_rules! expansions {
  39     ($($kind:ident: $ty:ty [$($vec:ident, $ty_elt:ty)*], $kind_name:expr, .$make:ident,
  40             $(.$fold:ident)*  $(lift .$fold_elt:ident)*,
  41             $(.$visit:ident)*  $(lift .$visit_elt:ident)*;)*) => {
  42         #[derive(Copy, Clone, PartialEq, Eq)]
  43         pub enum ExpansionKind { OptExpr, $( $kind, )*  }
  44         pub enum Expansion { OptExpr(Option<P<ast::Expr>>), $( $kind($ty), )* }
  45
  46         impl ExpansionKind {
  47             pub fn name(self) -> &'static str {
  48                 match self {
  49                     ExpansionKind::OptExpr => "expression",
  50                     $( ExpansionKind::$kind => $kind_name, )*
  51                 }
  52             }
  53
  54             fn make_from<'a>(self, result: Box<MacResult + 'a>) -> Option<Expansion> {
  55                 match self {
  56                     ExpansionKind::OptExpr => result.make_expr().map(Some).map(Expansion::OptExpr),
  57                     $( ExpansionKind::$kind => result.$make().map(Expansion::$kind), )*
  58                 }
  59             }
  60         }
  61
  62         impl Expansion {
  63             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  64                 match self {
  65                     Expansion::OptExpr(expr) => expr,
  66                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  67                 }
  68             }
  69             $( pub fn $make(self) -> $ty {
  70                 match self {
  71                     Expansion::$kind(ast) => ast,
  72                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  73                 }
  74             } )*
  75
  76             pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
  77                 use self::Expansion::*;
  78                 match self {
  79                     OptExpr(expr) => OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
  80                     $($( $kind(ast) => $kind(folder.$fold(ast)), )*)*
  81                     $($( $kind(ast) => {
  82                         $kind(ast.into_iter().flat_map(|ast| folder.$fold_elt(ast)).collect())
  83                     }, )*)*
  84                 }
  85             }
  86
  87             pub fn visit_with<V: Visitor>(&self, visitor: &mut V) {
  88                 match *self {
  89                     Expansion::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
  90                     Expansion::OptExpr(None) => {}
  91                     $($( Expansion::$kind(ref ast) => visitor.$visit(ast), )*)*
  92                     $($( Expansion::$kind(ref ast) => for ast in ast.as_slice() {
  93                         visitor.$visit_elt(ast);
  94                     }, )*)*
  95                 }
  96             }
  97         }
  98
  99         impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
 100             fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 101                 self.expand(Expansion::OptExpr(Some(expr))).make_opt_expr()
 102             }
 103             $($(fn $fold(&mut self, node: $ty) -> $ty {
 104                 self.expand(Expansion::$kind(node)).$make()
 105             })*)*
 106             $($(fn $fold_elt(&mut self, node: $ty_elt) -> $ty {
 107                 self.expand(Expansion::$kind(SmallVector::one(node))).$make()
 108             })*)*
 109         }
 110
 111         impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
 112             $(fn $make(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>) -> Option<$ty> {
 113                 Some(self.make(ExpansionKind::$kind).$make())
 114             })*
 115         }
 116     }
 117 }
 118
 119 expansions! {
 120     Expr: P<ast::Expr> [], "expression", .make_expr, .fold_expr, .visit_expr;
 121     Pat: P<ast::Pat>   [], "pattern",    .make_pat,  .fold_pat,  .visit_pat;
 122     Ty: P<ast::Ty>     [], "type",       .make_ty,   .fold_ty,   .visit_ty;
 123     Stmts: SmallVector<ast::Stmt> [SmallVector, ast::Stmt],
 124         "statement",  .make_stmts,       lift .fold_stmt, lift .visit_stmt;
 125     Items: SmallVector<P<ast::Item>> [SmallVector, P<ast::Item>],
 126         "item",       .make_items,       lift .fold_item, lift .visit_item;
 127     TraitItems: SmallVector<ast::TraitItem> [SmallVector, ast::TraitItem],
 128         "trait item", .make_trait_items, lift .fold_trait_item, lift .visit_trait_item;
 129     ImplItems: SmallVector<ast::ImplItem> [SmallVector, ast::ImplItem],
 130         "impl item",  .make_impl_items,  lift .fold_impl_item,  lift .visit_impl_item;
 131 }
 132
 133 impl ExpansionKind {
 134     fn dummy(self, span: Span) -> Expansion {
 135         self.make_from(DummyResult::any(span)).unwrap()
 136     }
 137
 138     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I) -> Expansion {
 139         let items = items.into_iter();
 140         match self {
 141             ExpansionKind::Items =>
 142                 Expansion::Items(items.map(Annotatable::expect_item).collect()),
 143             ExpansionKind::ImplItems =>
 144                 Expansion::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
 145             ExpansionKind::TraitItems =>
 146                 Expansion::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
 147             _ => unreachable!(),
 148         }
 149     }
 150 }
 151
 152 pub struct Invocation {
 153     pub kind: InvocationKind,
 154     expansion_kind: ExpansionKind,
 155     expansion_data: ExpansionData,
 156 }
 157
 158 pub enum InvocationKind {
 159     Bang {
 160         attrs: Vec<ast::Attribute>,
 161         mac: ast::Mac,
 162         ident: Option<Ident>,
 163         span: Span,
 164     },
 165     Attr {
 166         attr: ast::Attribute,
 167         item: Annotatable,
 168     },
 169 }
 170
 171 impl Invocation {
 172     fn span(&self) -> Span {
 173         match self.kind {
 174             InvocationKind::Bang { span, .. } => span,
 175             InvocationKind::Attr { ref attr, .. } => attr.span,
 176         }
 177     }
 178 }
 179
 180 pub struct MacroExpander<'a, 'b:'a> {
 181     pub cx: &'a mut ExtCtxt<'b>,
 182     monotonic: bool, // c.f. `cx.monotonic_expander()`
 183 }
 184
 185 impl<'a, 'b> MacroExpander<'a, 'b> {
 186     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 187         MacroExpander { cx: cx, monotonic: monotonic }
 188     }
 189
 190     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 191         self.cx.crate_root = std_inject::injected_crate_name(&krate);
 192         let mut module = ModuleData {
 193             mod_path: vec![token::str_to_ident(&self.cx.ecfg.crate_name)],
 194             directory: PathBuf::from(self.cx.codemap().span_to_filename(krate.span)),
 195         };
 196         module.directory.pop();
 197         self.cx.current_expansion.module = Rc::new(module);
 198
 199         let krate_item = Expansion::Items(SmallVector::one(P(ast::Item {
 200             attrs: krate.attrs,
 201             span: krate.span,
 202             node: ast::ItemKind::Mod(krate.module),
 203             ident: keywords::Invalid.ident(),
 204             id: ast::DUMMY_NODE_ID,
 205             vis: ast::Visibility::Public,
 206         })));
 207
 208         match self.expand(krate_item).make_items().pop().unwrap().unwrap() {
 209             ast::Item { attrs, node: ast::ItemKind::Mod(module), .. } => {
 210                 krate.attrs = attrs;
 211                 krate.module = module;
 212             },
 213             _ => unreachable!(),
 214         };
 215
 216         krate
 217     }
 218
 219     // Fully expand all the invocations in `expansion`.
 220     fn expand(&mut self, expansion: Expansion) -> Expansion {
 221         let orig_expansion_data = self.cx.current_expansion.clone();
 222         self.cx.current_expansion.depth = 0;
 223
 224         let (expansion, mut invocations) = self.collect_invocations(expansion);
 225         invocations.reverse();
 226
 227         let mut expansions = Vec::new();
 228         let mut undetermined_invocations = Vec::new();
 229         let (mut progress, mut force) = (false, !self.monotonic);
 230         loop {
 231             let invoc = if let Some(invoc) = invocations.pop() {
 232                 invoc
 233             } else if undetermined_invocations.is_empty() {
 234                 break
 235             } else {
 236                 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
 237                 force = !mem::replace(&mut progress, false);
 238                 continue
 239             };
 240
 241             let scope =
 242                 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
 243             let resolution = match invoc.kind {
 244                 InvocationKind::Bang { ref mac, .. } => {
 245                     self.cx.resolver.resolve_macro(scope, &mac.node.path, force)
 246                 }
 247                 InvocationKind::Attr { ref attr, .. } => {
 248                     let ident = ast::Ident::with_empty_ctxt(intern(&*attr.name()));
 249                     let path = ast::Path::from_ident(attr.span, ident);
 250                     self.cx.resolver.resolve_macro(scope, &path, force)
 251                 }
 252             };
 253             let ext = match resolution {
 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             let expansion = match ext {
 268                 Some(ext) => self.expand_invoc(invoc, ext),
 269                 None => invoc.expansion_kind.dummy(invoc.span()),
 270             };
 271
 272             let (expansion, new_invocations) = self.collect_invocations(expansion);
 273
 274             if expansions.len() < depth {
 275                 expansions.push(Vec::new());
 276             }
 277             expansions[depth - 1].push((mark.as_u32(), expansion));
 278             if !self.cx.ecfg.single_step {
 279                 invocations.extend(new_invocations.into_iter().rev());
 280             }
 281         }
 282
 283         self.cx.current_expansion = orig_expansion_data;
 284
 285         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 286         while let Some(expansions) = expansions.pop() {
 287             for (mark, expansion) in expansions.into_iter().rev() {
 288                 placeholder_expander.add(ast::NodeId::from_u32(mark), expansion);
 289             }
 290         }
 291
 292         expansion.fold_with(&mut placeholder_expander)
 293     }
 294
 295     fn collect_invocations(&mut self, expansion: Expansion) -> (Expansion, Vec<Invocation>) {
 296         let result = {
 297             let mut collector = InvocationCollector {
 298                 cfg: StripUnconfigured {
 299                     should_test: self.cx.ecfg.should_test,
 300                     sess: self.cx.parse_sess,
 301                     features: self.cx.ecfg.features,
 302                 },
 303                 cx: self.cx,
 304                 invocations: Vec::new(),
 305                 monotonic: self.monotonic,
 306             };
 307             (expansion.fold_with(&mut collector), collector.invocations)
 308         };
 309
 310         if self.monotonic {
 311             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 312             let mark = self.cx.current_expansion.mark;
 313             self.cx.resolver.visit_expansion(mark, &result.0);
 314             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 315         }
 316
 317         result
 318     }
 319
 320     fn expand_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 321         match invoc.kind {
 322             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext),
 323             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext),
 324         }
 325     }
 326
 327     fn expand_attr_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 328         let Invocation { expansion_kind: kind, .. } = invoc;
 329         let (attr, item) = match invoc.kind {
 330             InvocationKind::Attr { attr, item } => (attr, item),
 331             _ => unreachable!(),
 332         };
 333
 334         attr::mark_used(&attr);
 335         let name = intern(&attr.name());
 336         self.cx.bt_push(ExpnInfo {
 337             call_site: attr.span,
 338             callee: NameAndSpan {
 339                 format: MacroAttribute(name),
 340                 span: Some(attr.span),
 341                 allow_internal_unstable: false,
 342             }
 343         });
 344
 345         match *ext {
 346             MultiModifier(ref mac) => {
 347                 let item = mac.expand(self.cx, attr.span, &attr.node.value, item);
 348                 kind.expect_from_annotatables(item)
 349             }
 350             MultiDecorator(ref mac) => {
 351                 let mut items = Vec::new();
 352                 mac.expand(self.cx, attr.span, &attr.node.value, &item,
 353                            &mut |item| items.push(item));
 354                 items.push(item);
 355                 kind.expect_from_annotatables(items)
 356             }
 357             SyntaxExtension::AttrProcMacro(ref mac) => {
 358                 let attr_toks = TokenStream::from_tts(tts_for_attr(&attr, &self.cx.parse_sess));
 359                 let item_toks = TokenStream::from_tts(tts_for_item(&item, &self.cx.parse_sess));
 360
 361                 let tok_result = mac.expand(self.cx, attr.span, attr_toks, item_toks);
 362                 self.parse_expansion(tok_result, kind, name, attr.span)
 363             }
 364             SyntaxExtension::CustomDerive(_) => {
 365                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", name));
 366                 kind.dummy(attr.span)
 367             }
 368             _ => {
 369                 let msg = &format!("macro `{}` may not be used in attributes", name);
 370                 self.cx.span_err(attr.span, &msg);
 371                 kind.dummy(attr.span)
 372             }
 373         }
 374     }
 375
 376     /// Expand a macro invocation. Returns the result of expansion.
 377     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 378         let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
 379         let (attrs, mac, ident, span) = match invoc.kind {
 380             InvocationKind::Bang { attrs, mac, ident, span } => (attrs, mac, ident, span),
 381             _ => unreachable!(),
 382         };
 383         let Mac_ { path, tts, .. } = mac.node;
 384
 385         // Detect use of feature-gated or invalid attributes on macro invoations
 386         // since they will not be detected after macro expansion.
 387         for attr in attrs.iter() {
 388             feature_gate::check_attribute(&attr, &self.cx.parse_sess,
 389                                           &self.cx.parse_sess.codemap(),
 390                                           &self.cx.ecfg.features.unwrap());
 391         }
 392
 393         if path.segments.len() > 1 || path.global || !path.segments[0].parameters.is_empty() {
 394             self.cx.span_err(path.span, "expected macro name without module separators");
 395             return kind.dummy(span);
 396         }
 397
 398         let extname = path.segments[0].identifier.name;
 399         let ident = ident.unwrap_or(keywords::Invalid.ident());
 400         let marked_tts = mark_tts(&tts, mark);
 401         let opt_expanded = match *ext {
 402             NormalTT(ref expandfun, exp_span, allow_internal_unstable) => {
 403                 if ident.name != keywords::Invalid.name() {
 404                     let msg =
 405                         format!("macro {}! expects no ident argument, given '{}'", extname, ident);
 406                     self.cx.span_err(path.span, &msg);
 407                     return kind.dummy(span);
 408                 }
 409
 410                 self.cx.bt_push(ExpnInfo {
 411                     call_site: span,
 412                     callee: NameAndSpan {
 413                         format: MacroBang(extname),
 414                         span: exp_span,
 415                         allow_internal_unstable: allow_internal_unstable,
 416                     },
 417                 });
 418
 419                 kind.make_from(expandfun.expand(self.cx, span, &marked_tts))
 420             }
 421
 422             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 423                 if ident.name == keywords::Invalid.name() {
 424                     self.cx.span_err(path.span,
 425                                     &format!("macro {}! expects an ident argument", extname));
 426                     return kind.dummy(span);
 427                 };
 428
 429                 self.cx.bt_push(ExpnInfo {
 430                     call_site: span,
 431                     callee: NameAndSpan {
 432                         format: MacroBang(extname),
 433                         span: tt_span,
 434                         allow_internal_unstable: allow_internal_unstable,
 435                     }
 436                 });
 437
 438                 kind.make_from(expander.expand(self.cx, span, ident, marked_tts, attrs))
 439             }
 440
 441             MultiDecorator(..) | MultiModifier(..) | SyntaxExtension::AttrProcMacro(..) => {
 442                 self.cx.span_err(path.span,
 443                                  &format!("`{}` can only be used in attributes", extname));
 444                 return kind.dummy(span);
 445             }
 446
 447             SyntaxExtension::CustomDerive(..) => {
 448                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", extname));
 449                 return kind.dummy(span);
 450             }
 451
 452             SyntaxExtension::ProcMacro(ref expandfun) => {
 453                 if ident.name != keywords::Invalid.name() {
 454                     let msg =
 455                         format!("macro {}! expects no ident argument, given '{}'", extname, ident);
 456                     self.cx.span_err(path.span, &msg);
 457                     return kind.dummy(span);
 458                 }
 459
 460                 self.cx.bt_push(ExpnInfo {
 461                     call_site: span,
 462                     callee: NameAndSpan {
 463                         format: MacroBang(extname),
 464                         // FIXME procedural macros do not have proper span info
 465                         // yet, when they do, we should use it here.
 466                         span: None,
 467                         // FIXME probably want to follow macro_rules macros here.
 468                         allow_internal_unstable: false,
 469                     },
 470                 });
 471
 472                 let toks = TokenStream::from_tts(marked_tts);
 473                 let tok_result = expandfun.expand(self.cx, span, toks);
 474                 Some(self.parse_expansion(tok_result, kind, extname, span))
 475             }
 476         };
 477
 478         let expanded = if let Some(expanded) = opt_expanded {
 479             expanded
 480         } else {
 481             let msg = format!("non-{kind} macro in {kind} position: {name}",
 482                               name = path.segments[0].identifier.name, kind = kind.name());
 483             self.cx.span_err(path.span, &msg);
 484             return kind.dummy(span);
 485         };
 486
 487         expanded.fold_with(&mut Marker {
 488             mark: mark,
 489             expn_id: Some(self.cx.backtrace()),
 490         })
 491     }
 492
 493     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, name: Name, span: Span)
 494                        -> Expansion {
 495         let mut parser = self.cx.new_parser_from_tts(&toks.to_tts());
 496         let expansion = match parser.parse_expansion(kind, false) {
 497             Ok(expansion) => expansion,
 498             Err(mut err) => {
 499                 err.emit();
 500                 return kind.dummy(span);
 501             }
 502         };
 503         parser.ensure_complete_parse(name, kind.name(), span);
 504         // FIXME better span info
 505         expansion.fold_with(&mut ChangeSpan { span: span })
 506     }
 507 }
 508
 509 impl<'a> Parser<'a> {
 510     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 511                            -> PResult<'a, Expansion> {
 512         Ok(match kind {
 513             ExpansionKind::Items => {
 514                 let mut items = SmallVector::zero();
 515                 while let Some(item) = self.parse_item()? {
 516                     items.push(item);
 517                 }
 518                 Expansion::Items(items)
 519             }
 520             ExpansionKind::TraitItems => {
 521                 let mut items = SmallVector::zero();
 522                 while self.token != token::Eof {
 523                     items.push(self.parse_trait_item()?);
 524                 }
 525                 Expansion::TraitItems(items)
 526             }
 527             ExpansionKind::ImplItems => {
 528                 let mut items = SmallVector::zero();
 529                 while self.token != token::Eof {
 530                     items.push(self.parse_impl_item()?);
 531                 }
 532                 Expansion::ImplItems(items)
 533             }
 534             ExpansionKind::Stmts => {
 535                 let mut stmts = SmallVector::zero();
 536                 while self.token != token::Eof {
 537                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 538                         stmts.push(stmt);
 539                     }
 540                 }
 541                 Expansion::Stmts(stmts)
 542             }
 543             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 544             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 545             ExpansionKind::Ty => Expansion::Ty(self.parse_ty()?),
 546             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 547         })
 548     }
 549
 550     pub fn ensure_complete_parse(&mut self, macro_name: ast::Name, kind_name: &str, span: Span) {
 551         if self.token != token::Eof {
 552             let msg = format!("macro expansion ignores token `{}` and any following",
 553                               self.this_token_to_string());
 554             let mut err = self.diagnostic().struct_span_err(self.span, &msg);
 555             let msg = format!("caused by the macro expansion here; the usage \
 556                                of `{}!` is likely invalid in {} context",
 557                                macro_name, kind_name);
 558             err.span_note(span, &msg).emit();
 559         }
 560     }
 561 }
 562
 563 struct InvocationCollector<'a, 'b: 'a> {
 564     cx: &'a mut ExtCtxt<'b>,
 565     cfg: StripUnconfigured<'a>,
 566     invocations: Vec<Invocation>,
 567     monotonic: bool,
 568 }
 569
 570 macro_rules! fully_configure {
 571     ($this:ident, $node:ident, $noop_fold:ident) => {
 572         match $noop_fold($node, &mut $this.cfg).pop() {
 573             Some(node) => node,
 574             None => return SmallVector::zero(),
 575         }
 576     }
 577 }
 578
 579 impl<'a, 'b> InvocationCollector<'a, 'b> {
 580     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 581         let mark = Mark::fresh();
 582         self.invocations.push(Invocation {
 583             kind: kind,
 584             expansion_kind: expansion_kind,
 585             expansion_data: ExpansionData {
 586                 mark: mark,
 587                 depth: self.cx.current_expansion.depth + 1,
 588                 ..self.cx.current_expansion.clone()
 589             },
 590         });
 591         placeholder(expansion_kind, ast::NodeId::from_u32(mark.as_u32()))
 592     }
 593
 594     fn collect_bang(
 595         &mut self, mac: ast::Mac, attrs: Vec<ast::Attribute>, span: Span, kind: ExpansionKind,
 596     ) -> Expansion {
 597         self.collect(kind, InvocationKind::Bang { attrs: attrs, mac: mac, ident: None, span: span })
 598     }
 599
 600     fn collect_attr(&mut self, attr: ast::Attribute, item: Annotatable, kind: ExpansionKind)
 601                     -> Expansion {
 602         self.collect(kind, InvocationKind::Attr { attr: attr, item: item })
 603     }
 604
 605     // If `item` is an attr invocation, remove and return the macro attribute.
 606     fn classify_item<T: HasAttrs>(&mut self, mut item: T) -> (T, Option<ast::Attribute>) {
 607         let mut attr = None;
 608         item = item.map_attrs(|mut attrs| {
 609             attr = self.cx.resolver.find_attr_invoc(&mut attrs);
 610             attrs
 611         });
 612         (item, attr)
 613     }
 614
 615     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 616         self.cfg.configure(node)
 617     }
 618 }
 619
 620 // These are pretty nasty. Ideally, we would keep the tokens around, linked from
 621 // the AST. However, we don't so we need to create new ones. Since the item might
 622 // have come from a macro expansion (possibly only in part), we can't use the
 623 // existing codemap.
 624 //
 625 // Therefore, we must use the pretty printer (yuck) to turn the AST node into a
 626 // string, which we then re-tokenise (double yuck), but first we have to patch
 627 // the pretty-printed string on to the end of the existing codemap (infinity-yuck).
 628 fn tts_for_item(item: &Annotatable, parse_sess: &ParseSess) -> Vec<TokenTree> {
 629     let text = match *item {
 630         Annotatable::Item(ref i) => pprust::item_to_string(i),
 631         Annotatable::TraitItem(ref ti) => pprust::trait_item_to_string(ti),
 632         Annotatable::ImplItem(ref ii) => pprust::impl_item_to_string(ii),
 633     };
 634     string_to_tts(text, parse_sess)
 635 }
 636
 637 fn tts_for_attr(attr: &ast::Attribute, parse_sess: &ParseSess) -> Vec<TokenTree> {
 638     string_to_tts(pprust::attr_to_string(attr), parse_sess)
 639 }
 640
 641 fn string_to_tts(text: String, parse_sess: &ParseSess) -> Vec<TokenTree> {
 642     let filemap = parse_sess.codemap()
 643                             .new_filemap(String::from("<macro expansion>"), None, text);
 644
 645     let lexer = lexer::StringReader::new(&parse_sess.span_diagnostic, filemap);
 646     let mut parser = Parser::new(parse_sess, Box::new(lexer));
 647     panictry!(parser.parse_all_token_trees())
 648 }
 649
 650 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 651     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 652         let mut expr = self.cfg.configure_expr(expr).unwrap();
 653         expr.node = self.cfg.configure_expr_kind(expr.node);
 654
 655         if let ast::ExprKind::Mac(mac) = expr.node {
 656             self.collect_bang(mac, expr.attrs.into(), expr.span, ExpansionKind::Expr).make_expr()
 657         } else {
 658             P(noop_fold_expr(expr, self))
 659         }
 660     }
 661
 662     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 663         let mut expr = configure!(self, expr).unwrap();
 664         expr.node = self.cfg.configure_expr_kind(expr.node);
 665
 666         if let ast::ExprKind::Mac(mac) = expr.node {
 667             self.collect_bang(mac, expr.attrs.into(), expr.span, ExpansionKind::OptExpr)
 668                 .make_opt_expr()
 669         } else {
 670             Some(P(noop_fold_expr(expr, self)))
 671         }
 672     }
 673
 674     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 675         match pat.node {
 676             PatKind::Mac(_) => {}
 677             _ => return noop_fold_pat(pat, self),
 678         }
 679
 680         pat.and_then(|pat| match pat.node {
 681             PatKind::Mac(mac) =>
 682                 self.collect_bang(mac, Vec::new(), pat.span, ExpansionKind::Pat).make_pat(),
 683             _ => unreachable!(),
 684         })
 685     }
 686
 687     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 688         let stmt = match self.cfg.configure_stmt(stmt) {
 689             Some(stmt) => stmt,
 690             None => return SmallVector::zero(),
 691         };
 692
 693         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 694             mac.unwrap()
 695         } else {
 696             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 697             let ast::Stmt { id, node, span } = stmt;
 698             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 699                 ast::Stmt { id: id, node: node, span: span }
 700             }).collect()
 701         };
 702
 703         let mut placeholder =
 704             self.collect_bang(mac, attrs.into(), stmt.span, ExpansionKind::Stmts).make_stmts();
 705
 706         // If this is a macro invocation with a semicolon, then apply that
 707         // semicolon to the final statement produced by expansion.
 708         if style == MacStmtStyle::Semicolon {
 709             if let Some(stmt) = placeholder.pop() {
 710                 placeholder.push(stmt.add_trailing_semicolon());
 711             }
 712         }
 713
 714         placeholder
 715     }
 716
 717     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 718         let no_noninline_mod = mem::replace(&mut self.cx.current_expansion.no_noninline_mod, true);
 719         let result = noop_fold_block(block, self);
 720         self.cx.current_expansion.no_noninline_mod = no_noninline_mod;
 721         result
 722     }
 723
 724     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 725         let item = configure!(self, item);
 726
 727         let (mut item, attr) = self.classify_item(item);
 728         if let Some(attr) = attr {
 729             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 730             return self.collect_attr(attr, item, ExpansionKind::Items).make_items();
 731         }
 732
 733         match item.node {
 734             ast::ItemKind::Mac(..) => {
 735                 if match item.node {
 736                     ItemKind::Mac(ref mac) => mac.node.path.segments.is_empty(),
 737                     _ => unreachable!(),
 738                 } {
 739                     return SmallVector::one(item);
 740                 }
 741
 742                 item.and_then(|item| match item.node {
 743                     ItemKind::Mac(mac) => {
 744                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 745                             mac: mac,
 746                             attrs: item.attrs,
 747                             ident: Some(item.ident),
 748                             span: item.span,
 749                         }).make_items()
 750                     }
 751                     _ => unreachable!(),
 752                 })
 753             }
 754             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 755                 if item.ident == keywords::Invalid.ident() {
 756                     return noop_fold_item(item, self);
 757                 }
 758
 759                 let orig_no_noninline_mod = self.cx.current_expansion.no_noninline_mod;
 760                 let mut module = (*self.cx.current_expansion.module).clone();
 761                 module.mod_path.push(item.ident);
 762
 763                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 764                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 765                 // Thus, if `inner` is the dummy span, we know the module is inline.
 766                 let inline_module = item.span.contains(inner) || inner == syntax_pos::DUMMY_SP;
 767
 768                 if inline_module {
 769                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 770                         self.cx.current_expansion.no_noninline_mod = false;
 771                         module.directory.push(&*path);
 772                     } else {
 773                         module.directory.push(&*item.ident.name.as_str());
 774                     }
 775                 } else {
 776                     self.cx.current_expansion.no_noninline_mod = false;
 777                     module.directory =
 778                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 779                     module.directory.pop();
 780                 }
 781
 782                 let orig_module =
 783                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 784                 let result = noop_fold_item(item, self);
 785                 self.cx.current_expansion.module = orig_module;
 786                 self.cx.current_expansion.no_noninline_mod = orig_no_noninline_mod;
 787                 return result;
 788             }
 789             // Ensure that test functions are accessible from the test harness.
 790             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 791                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 792                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 793                 }
 794                 noop_fold_item(item, self)
 795             }
 796             _ => noop_fold_item(item, self),
 797         }
 798     }
 799
 800     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 801         let item = configure!(self, item);
 802
 803         let (item, attr) = self.classify_item(item);
 804         if let Some(attr) = attr {
 805             let item =
 806                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 807             return self.collect_attr(attr, item, ExpansionKind::TraitItems).make_trait_items()
 808         }
 809
 810         match item.node {
 811             ast::TraitItemKind::Macro(mac) => {
 812                 let ast::TraitItem { attrs, span, .. } = item;
 813                 self.collect_bang(mac, attrs, span, ExpansionKind::TraitItems).make_trait_items()
 814             }
 815             _ => fold::noop_fold_trait_item(item, self),
 816         }
 817     }
 818
 819     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 820         let item = configure!(self, item);
 821
 822         let (item, attr) = self.classify_item(item);
 823         if let Some(attr) = attr {
 824             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 825             return self.collect_attr(attr, item, ExpansionKind::ImplItems).make_impl_items();
 826         }
 827
 828         match item.node {
 829             ast::ImplItemKind::Macro(mac) => {
 830                 let ast::ImplItem { attrs, span, .. } = item;
 831                 self.collect_bang(mac, attrs, span, ExpansionKind::ImplItems).make_impl_items()
 832             }
 833             _ => fold::noop_fold_impl_item(item, self),
 834         }
 835     }
 836
 837     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
 838         let ty = match ty.node {
 839             ast::TyKind::Mac(_) => ty.unwrap(),
 840             _ => return fold::noop_fold_ty(ty, self),
 841         };
 842
 843         match ty.node {
 844             ast::TyKind::Mac(mac) =>
 845                 self.collect_bang(mac, Vec::new(), ty.span, ExpansionKind::Ty).make_ty(),
 846             _ => unreachable!(),
 847         }
 848     }
 849
 850     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
 851         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
 852     }
 853
 854     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
 855         noop_fold_item_kind(self.cfg.configure_item_kind(item), self)
 856     }
 857
 858     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
 859         if self.monotonic {
 860             assert_eq!(id, ast::DUMMY_NODE_ID);
 861             self.cx.resolver.next_node_id()
 862         } else {
 863             id
 864         }
 865     }
 866 }
 867
 868 pub struct ExpansionConfig<'feat> {
 869     pub crate_name: String,
 870     pub features: Option<&'feat Features>,
 871     pub recursion_limit: usize,
 872     pub trace_mac: bool,
 873     pub should_test: bool, // If false, strip `#[test]` nodes
 874     pub single_step: bool,
 875     pub keep_macs: bool,
 876 }
 877
 878 macro_rules! feature_tests {
 879     ($( fn $getter:ident = $field:ident, )*) => {
 880         $(
 881             pub fn $getter(&self) -> bool {
 882                 match self.features {
 883                     Some(&Features { $field: true, .. }) => true,
 884                     _ => false,
 885                 }
 886             }
 887         )*
 888     }
 889 }
 890
 891 impl<'feat> ExpansionConfig<'feat> {
 892     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
 893         ExpansionConfig {
 894             crate_name: crate_name,
 895             features: None,
 896             recursion_limit: 64,
 897             trace_mac: false,
 898             should_test: false,
 899             single_step: false,
 900             keep_macs: false,
 901         }
 902     }
 903
 904     feature_tests! {
 905         fn enable_quotes = quote,
 906         fn enable_asm = asm,
 907         fn enable_log_syntax = log_syntax,
 908         fn enable_concat_idents = concat_idents,
 909         fn enable_trace_macros = trace_macros,
 910         fn enable_allow_internal_unstable = allow_internal_unstable,
 911         fn enable_custom_derive = custom_derive,
 912         fn enable_pushpop_unsafe = pushpop_unsafe,
 913         fn enable_proc_macro = proc_macro,
 914     }
 915 }
 916
 917 // A Marker adds the given mark to the syntax context and
 918 // sets spans' `expn_id` to the given expn_id (unless it is `None`).
 919 struct Marker { mark: Mark, expn_id: Option<ExpnId> }
 920
 921 impl Folder for Marker {
 922     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
 923         ident.ctxt = ident.ctxt.apply_mark(self.mark);
 924         ident
 925     }
 926     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
 927         noop_fold_mac(mac, self)
 928     }
 929
 930     fn new_span(&mut self, mut span: Span) -> Span {
 931         if let Some(expn_id) = self.expn_id {
 932             span.expn_id = expn_id;
 933         }
 934         span
 935     }
 936 }
 937
 938 // apply a given mark to the given token trees. Used prior to expansion of a macro.
 939 pub fn mark_tts(tts: &[TokenTree], m: Mark) -> Vec<TokenTree> {
 940     noop_fold_tts(tts, &mut Marker{mark:m, expn_id: None})
 941 }