ParseTemplate.cpp revision 212904
1//===--- ParseTemplate.cpp - Template Parsing -----------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements parsing of C++ templates.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Parse/Parser.h"
15#include "clang/Parse/ParseDiagnostic.h"
16#include "clang/Sema/DeclSpec.h"
17#include "clang/Sema/ParsedTemplate.h"
18#include "clang/Sema/Scope.h"
19#include "RAIIObjectsForParser.h"
20using namespace clang;
21
22/// \brief Parse a template declaration, explicit instantiation, or
23/// explicit specialization.
24Decl *
25Parser::ParseDeclarationStartingWithTemplate(unsigned Context,
26                                             SourceLocation &DeclEnd,
27                                             AccessSpecifier AS) {
28  if (Tok.is(tok::kw_template) && NextToken().isNot(tok::less))
29    return ParseExplicitInstantiation(SourceLocation(), ConsumeToken(),
30                                      DeclEnd);
31
32  return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AS);
33}
34
35/// \brief RAII class that manages the template parameter depth.
36namespace {
37  class TemplateParameterDepthCounter {
38    unsigned &Depth;
39    unsigned AddedLevels;
40
41  public:
42    explicit TemplateParameterDepthCounter(unsigned &Depth)
43      : Depth(Depth), AddedLevels(0) { }
44
45    ~TemplateParameterDepthCounter() {
46      Depth -= AddedLevels;
47    }
48
49    void operator++() {
50      ++Depth;
51      ++AddedLevels;
52    }
53
54    operator unsigned() const { return Depth; }
55  };
56}
57
58/// \brief Parse a template declaration or an explicit specialization.
59///
60/// Template declarations include one or more template parameter lists
61/// and either the function or class template declaration. Explicit
62/// specializations contain one or more 'template < >' prefixes
63/// followed by a (possibly templated) declaration. Since the
64/// syntactic form of both features is nearly identical, we parse all
65/// of the template headers together and let semantic analysis sort
66/// the declarations from the explicit specializations.
67///
68///       template-declaration: [C++ temp]
69///         'export'[opt] 'template' '<' template-parameter-list '>' declaration
70///
71///       explicit-specialization: [ C++ temp.expl.spec]
72///         'template' '<' '>' declaration
73Decl *
74Parser::ParseTemplateDeclarationOrSpecialization(unsigned Context,
75                                                 SourceLocation &DeclEnd,
76                                                 AccessSpecifier AS) {
77  assert((Tok.is(tok::kw_export) || Tok.is(tok::kw_template)) &&
78         "Token does not start a template declaration.");
79
80  // Enter template-parameter scope.
81  ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
82
83  // Tell the action that names should be checked in the context of
84  // the declaration to come.
85  ParsingDeclRAIIObject ParsingTemplateParams(*this);
86
87  // Parse multiple levels of template headers within this template
88  // parameter scope, e.g.,
89  //
90  //   template<typename T>
91  //     template<typename U>
92  //       class A<T>::B { ... };
93  //
94  // We parse multiple levels non-recursively so that we can build a
95  // single data structure containing all of the template parameter
96  // lists to easily differentiate between the case above and:
97  //
98  //   template<typename T>
99  //   class A {
100  //     template<typename U> class B;
101  //   };
102  //
103  // In the first case, the action for declaring A<T>::B receives
104  // both template parameter lists. In the second case, the action for
105  // defining A<T>::B receives just the inner template parameter list
106  // (and retrieves the outer template parameter list from its
107  // context).
108  bool isSpecialization = true;
109  bool LastParamListWasEmpty = false;
110  TemplateParameterLists ParamLists;
111  TemplateParameterDepthCounter Depth(TemplateParameterDepth);
112  do {
113    // Consume the 'export', if any.
114    SourceLocation ExportLoc;
115    if (Tok.is(tok::kw_export)) {
116      ExportLoc = ConsumeToken();
117    }
118
119    // Consume the 'template', which should be here.
120    SourceLocation TemplateLoc;
121    if (Tok.is(tok::kw_template)) {
122      TemplateLoc = ConsumeToken();
123    } else {
124      Diag(Tok.getLocation(), diag::err_expected_template);
125      return 0;
126    }
127
128    // Parse the '<' template-parameter-list '>'
129    SourceLocation LAngleLoc, RAngleLoc;
130    llvm::SmallVector<Decl*, 4> TemplateParams;
131    if (ParseTemplateParameters(Depth, TemplateParams, LAngleLoc,
132                                RAngleLoc)) {
133      // Skip until the semi-colon or a }.
134      SkipUntil(tok::r_brace, true, true);
135      if (Tok.is(tok::semi))
136        ConsumeToken();
137      return 0;
138    }
139
140    ParamLists.push_back(
141      Actions.ActOnTemplateParameterList(Depth, ExportLoc,
142                                         TemplateLoc, LAngleLoc,
143                                         TemplateParams.data(),
144                                         TemplateParams.size(), RAngleLoc));
145
146    if (!TemplateParams.empty()) {
147      isSpecialization = false;
148      ++Depth;
149    } else {
150      LastParamListWasEmpty = true;
151    }
152  } while (Tok.is(tok::kw_export) || Tok.is(tok::kw_template));
153
154  // Parse the actual template declaration.
155  return ParseSingleDeclarationAfterTemplate(Context,
156                                             ParsedTemplateInfo(&ParamLists,
157                                                             isSpecialization,
158                                                         LastParamListWasEmpty),
159                                             ParsingTemplateParams,
160                                             DeclEnd, AS);
161}
162
163/// \brief Parse a single declaration that declares a template,
164/// template specialization, or explicit instantiation of a template.
165///
166/// \param TemplateParams if non-NULL, the template parameter lists
167/// that preceded this declaration. In this case, the declaration is a
168/// template declaration, out-of-line definition of a template, or an
169/// explicit template specialization. When NULL, the declaration is an
170/// explicit template instantiation.
171///
172/// \param TemplateLoc when TemplateParams is NULL, the location of
173/// the 'template' keyword that indicates that we have an explicit
174/// template instantiation.
175///
176/// \param DeclEnd will receive the source location of the last token
177/// within this declaration.
178///
179/// \param AS the access specifier associated with this
180/// declaration. Will be AS_none for namespace-scope declarations.
181///
182/// \returns the new declaration.
183Decl *
184Parser::ParseSingleDeclarationAfterTemplate(
185                                       unsigned Context,
186                                       const ParsedTemplateInfo &TemplateInfo,
187                                       ParsingDeclRAIIObject &DiagsFromTParams,
188                                       SourceLocation &DeclEnd,
189                                       AccessSpecifier AS) {
190  assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
191         "Template information required");
192
193  if (Context == Declarator::MemberContext) {
194    // We are parsing a member template.
195    ParseCXXClassMemberDeclaration(AS, TemplateInfo, &DiagsFromTParams);
196    return 0;
197  }
198
199  // Parse the declaration specifiers, stealing the accumulated
200  // diagnostics from the template parameters.
201  ParsingDeclSpec DS(DiagsFromTParams);
202
203  if (getLang().CPlusPlus0x && isCXX0XAttributeSpecifier())
204    DS.AddAttributes(ParseCXX0XAttributes().AttrList);
205
206  ParseDeclarationSpecifiers(DS, TemplateInfo, AS,
207                             getDeclSpecContextFromDeclaratorContext(Context));
208
209  if (Tok.is(tok::semi)) {
210    DeclEnd = ConsumeToken();
211    Decl *Decl = Actions.ParsedFreeStandingDeclSpec(getCurScope(), AS, DS);
212    DS.complete(Decl);
213    return Decl;
214  }
215
216  // Parse the declarator.
217  ParsingDeclarator DeclaratorInfo(*this, DS, (Declarator::TheContext)Context);
218  ParseDeclarator(DeclaratorInfo);
219  // Error parsing the declarator?
220  if (!DeclaratorInfo.hasName()) {
221    // If so, skip until the semi-colon or a }.
222    SkipUntil(tok::r_brace, true, true);
223    if (Tok.is(tok::semi))
224      ConsumeToken();
225    return 0;
226  }
227
228  // If we have a declaration or declarator list, handle it.
229  if (isDeclarationAfterDeclarator()) {
230    // Parse this declaration.
231    Decl *ThisDecl = ParseDeclarationAfterDeclarator(DeclaratorInfo,
232                                                     TemplateInfo);
233
234    if (Tok.is(tok::comma)) {
235      Diag(Tok, diag::err_multiple_template_declarators)
236        << (int)TemplateInfo.Kind;
237      SkipUntil(tok::semi, true, false);
238      return ThisDecl;
239    }
240
241    // Eat the semi colon after the declaration.
242    ExpectAndConsume(tok::semi, diag::err_expected_semi_declaration);
243    DS.complete(ThisDecl);
244    return ThisDecl;
245  }
246
247  if (DeclaratorInfo.isFunctionDeclarator() &&
248      isStartOfFunctionDefinition(DeclaratorInfo)) {
249    if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
250      Diag(Tok, diag::err_function_declared_typedef);
251
252      if (Tok.is(tok::l_brace)) {
253        // This recovery skips the entire function body. It would be nice
254        // to simply call ParseFunctionDefinition() below, however Sema
255        // assumes the declarator represents a function, not a typedef.
256        ConsumeBrace();
257        SkipUntil(tok::r_brace, true);
258      } else {
259        SkipUntil(tok::semi);
260      }
261      return 0;
262    }
263    return ParseFunctionDefinition(DeclaratorInfo, TemplateInfo);
264  }
265
266  if (DeclaratorInfo.isFunctionDeclarator())
267    Diag(Tok, diag::err_expected_fn_body);
268  else
269    Diag(Tok, diag::err_invalid_token_after_toplevel_declarator);
270  SkipUntil(tok::semi);
271  return 0;
272}
273
274/// ParseTemplateParameters - Parses a template-parameter-list enclosed in
275/// angle brackets. Depth is the depth of this template-parameter-list, which
276/// is the number of template headers directly enclosing this template header.
277/// TemplateParams is the current list of template parameters we're building.
278/// The template parameter we parse will be added to this list. LAngleLoc and
279/// RAngleLoc will receive the positions of the '<' and '>', respectively,
280/// that enclose this template parameter list.
281///
282/// \returns true if an error occurred, false otherwise.
283bool Parser::ParseTemplateParameters(unsigned Depth,
284                               llvm::SmallVectorImpl<Decl*> &TemplateParams,
285                                     SourceLocation &LAngleLoc,
286                                     SourceLocation &RAngleLoc) {
287  // Get the template parameter list.
288  if (!Tok.is(tok::less)) {
289    Diag(Tok.getLocation(), diag::err_expected_less_after) << "template";
290    return true;
291  }
292  LAngleLoc = ConsumeToken();
293
294  // Try to parse the template parameter list.
295  if (Tok.is(tok::greater))
296    RAngleLoc = ConsumeToken();
297  else if (ParseTemplateParameterList(Depth, TemplateParams)) {
298    if (!Tok.is(tok::greater)) {
299      Diag(Tok.getLocation(), diag::err_expected_greater);
300      return true;
301    }
302    RAngleLoc = ConsumeToken();
303  }
304  return false;
305}
306
307/// ParseTemplateParameterList - Parse a template parameter list. If
308/// the parsing fails badly (i.e., closing bracket was left out), this
309/// will try to put the token stream in a reasonable position (closing
310/// a statement, etc.) and return false.
311///
312///       template-parameter-list:    [C++ temp]
313///         template-parameter
314///         template-parameter-list ',' template-parameter
315bool
316Parser::ParseTemplateParameterList(unsigned Depth,
317                             llvm::SmallVectorImpl<Decl*> &TemplateParams) {
318  while (1) {
319    if (Decl *TmpParam
320          = ParseTemplateParameter(Depth, TemplateParams.size())) {
321      TemplateParams.push_back(TmpParam);
322    } else {
323      // If we failed to parse a template parameter, skip until we find
324      // a comma or closing brace.
325      SkipUntil(tok::comma, tok::greater, true, true);
326    }
327
328    // Did we find a comma or the end of the template parmeter list?
329    if (Tok.is(tok::comma)) {
330      ConsumeToken();
331    } else if (Tok.is(tok::greater)) {
332      // Don't consume this... that's done by template parser.
333      break;
334    } else {
335      // Somebody probably forgot to close the template. Skip ahead and
336      // try to get out of the expression. This error is currently
337      // subsumed by whatever goes on in ParseTemplateParameter.
338      // TODO: This could match >>, and it would be nice to avoid those
339      // silly errors with template <vec<T>>.
340      // Diag(Tok.getLocation(), diag::err_expected_comma_greater);
341      SkipUntil(tok::greater, true, true);
342      return false;
343    }
344  }
345  return true;
346}
347
348/// \brief Determine whether the parser is at the start of a template
349/// type parameter.
350bool Parser::isStartOfTemplateTypeParameter() {
351  if (Tok.is(tok::kw_class)) {
352    // "class" may be the start of an elaborated-type-specifier or a
353    // type-parameter. Per C++ [temp.param]p3, we prefer the type-parameter.
354    switch (NextToken().getKind()) {
355    case tok::equal:
356    case tok::comma:
357    case tok::greater:
358    case tok::greatergreater:
359    case tok::ellipsis:
360      return true;
361
362    case tok::identifier:
363      // This may be either a type-parameter or an elaborated-type-specifier.
364      // We have to look further.
365      break;
366
367    default:
368      return false;
369    }
370
371    switch (GetLookAheadToken(2).getKind()) {
372    case tok::equal:
373    case tok::comma:
374    case tok::greater:
375    case tok::greatergreater:
376      return true;
377
378    default:
379      return false;
380    }
381  }
382
383  if (Tok.isNot(tok::kw_typename))
384    return false;
385
386  // C++ [temp.param]p2:
387  //   There is no semantic difference between class and typename in a
388  //   template-parameter. typename followed by an unqualified-id
389  //   names a template type parameter. typename followed by a
390  //   qualified-id denotes the type in a non-type
391  //   parameter-declaration.
392  Token Next = NextToken();
393
394  // If we have an identifier, skip over it.
395  if (Next.getKind() == tok::identifier)
396    Next = GetLookAheadToken(2);
397
398  switch (Next.getKind()) {
399  case tok::equal:
400  case tok::comma:
401  case tok::greater:
402  case tok::greatergreater:
403  case tok::ellipsis:
404    return true;
405
406  default:
407    return false;
408  }
409}
410
411/// ParseTemplateParameter - Parse a template-parameter (C++ [temp.param]).
412///
413///       template-parameter: [C++ temp.param]
414///         type-parameter
415///         parameter-declaration
416///
417///       type-parameter: (see below)
418///         'class' ...[opt][C++0x] identifier[opt]
419///         'class' identifier[opt] '=' type-id
420///         'typename' ...[opt][C++0x] identifier[opt]
421///         'typename' identifier[opt] '=' type-id
422///         'template' ...[opt][C++0x] '<' template-parameter-list '>' 'class' identifier[opt]
423///         'template' '<' template-parameter-list '>' 'class' identifier[opt] = id-expression
424Decl *Parser::ParseTemplateParameter(unsigned Depth, unsigned Position) {
425  if (isStartOfTemplateTypeParameter())
426    return ParseTypeParameter(Depth, Position);
427
428  if (Tok.is(tok::kw_template))
429    return ParseTemplateTemplateParameter(Depth, Position);
430
431  // If it's none of the above, then it must be a parameter declaration.
432  // NOTE: This will pick up errors in the closure of the template parameter
433  // list (e.g., template < ; Check here to implement >> style closures.
434  return ParseNonTypeTemplateParameter(Depth, Position);
435}
436
437/// ParseTypeParameter - Parse a template type parameter (C++ [temp.param]).
438/// Other kinds of template parameters are parsed in
439/// ParseTemplateTemplateParameter and ParseNonTypeTemplateParameter.
440///
441///       type-parameter:     [C++ temp.param]
442///         'class' ...[opt][C++0x] identifier[opt]
443///         'class' identifier[opt] '=' type-id
444///         'typename' ...[opt][C++0x] identifier[opt]
445///         'typename' identifier[opt] '=' type-id
446Decl *Parser::ParseTypeParameter(unsigned Depth, unsigned Position) {
447  assert((Tok.is(tok::kw_class) || Tok.is(tok::kw_typename)) &&
448         "A type-parameter starts with 'class' or 'typename'");
449
450  // Consume the 'class' or 'typename' keyword.
451  bool TypenameKeyword = Tok.is(tok::kw_typename);
452  SourceLocation KeyLoc = ConsumeToken();
453
454  // Grab the ellipsis (if given).
455  bool Ellipsis = false;
456  SourceLocation EllipsisLoc;
457  if (Tok.is(tok::ellipsis)) {
458    Ellipsis = true;
459    EllipsisLoc = ConsumeToken();
460
461    if (!getLang().CPlusPlus0x)
462      Diag(EllipsisLoc, diag::err_variadic_templates);
463  }
464
465  // Grab the template parameter name (if given)
466  SourceLocation NameLoc;
467  IdentifierInfo* ParamName = 0;
468  if (Tok.is(tok::identifier)) {
469    ParamName = Tok.getIdentifierInfo();
470    NameLoc = ConsumeToken();
471  } else if (Tok.is(tok::equal) || Tok.is(tok::comma) ||
472            Tok.is(tok::greater)) {
473    // Unnamed template parameter. Don't have to do anything here, just
474    // don't consume this token.
475  } else {
476    Diag(Tok.getLocation(), diag::err_expected_ident);
477    return 0;
478  }
479
480  // Grab a default argument (if available).
481  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
482  // we introduce the type parameter into the local scope.
483  SourceLocation EqualLoc;
484  ParsedType DefaultArg;
485  if (Tok.is(tok::equal)) {
486    EqualLoc = ConsumeToken();
487    DefaultArg = ParseTypeName().get();
488  }
489
490  return Actions.ActOnTypeParameter(getCurScope(), TypenameKeyword, Ellipsis,
491                                    EllipsisLoc, KeyLoc, ParamName, NameLoc,
492                                    Depth, Position, EqualLoc, DefaultArg);
493}
494
495/// ParseTemplateTemplateParameter - Handle the parsing of template
496/// template parameters.
497///
498///       type-parameter:    [C++ temp.param]
499///         'template' '<' template-parameter-list '>' 'class' identifier[opt]
500///         'template' '<' template-parameter-list '>' 'class' identifier[opt] = id-expression
501Decl *
502Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
503  assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");
504
505  // Handle the template <...> part.
506  SourceLocation TemplateLoc = ConsumeToken();
507  llvm::SmallVector<Decl*,8> TemplateParams;
508  SourceLocation LAngleLoc, RAngleLoc;
509  {
510    ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
511    if (ParseTemplateParameters(Depth + 1, TemplateParams, LAngleLoc,
512                               RAngleLoc)) {
513      return 0;
514    }
515  }
516
517  // Generate a meaningful error if the user forgot to put class before the
518  // identifier, comma, or greater.
519  if (!Tok.is(tok::kw_class)) {
520    Diag(Tok.getLocation(), diag::err_expected_class_before)
521      << PP.getSpelling(Tok);
522    return 0;
523  }
524  SourceLocation ClassLoc = ConsumeToken();
525
526  // Get the identifier, if given.
527  SourceLocation NameLoc;
528  IdentifierInfo* ParamName = 0;
529  if (Tok.is(tok::identifier)) {
530    ParamName = Tok.getIdentifierInfo();
531    NameLoc = ConsumeToken();
532  } else if (Tok.is(tok::equal) || Tok.is(tok::comma) || Tok.is(tok::greater)) {
533    // Unnamed template parameter. Don't have to do anything here, just
534    // don't consume this token.
535  } else {
536    Diag(Tok.getLocation(), diag::err_expected_ident);
537    return 0;
538  }
539
540  TemplateParamsTy *ParamList =
541    Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
542                                       TemplateLoc, LAngleLoc,
543                                       &TemplateParams[0],
544                                       TemplateParams.size(),
545                                       RAngleLoc);
546
547  // Grab a default argument (if available).
548  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
549  // we introduce the template parameter into the local scope.
550  SourceLocation EqualLoc;
551  ParsedTemplateArgument DefaultArg;
552  if (Tok.is(tok::equal)) {
553    EqualLoc = ConsumeToken();
554    DefaultArg = ParseTemplateTemplateArgument();
555    if (DefaultArg.isInvalid()) {
556      Diag(Tok.getLocation(),
557           diag::err_default_template_template_parameter_not_template);
558      static const tok::TokenKind EndToks[] = {
559        tok::comma, tok::greater, tok::greatergreater
560      };
561      SkipUntil(EndToks, 3, true, true);
562    }
563  }
564
565  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
566                                                ParamList, ParamName,
567                                                NameLoc, Depth, Position,
568                                                EqualLoc, DefaultArg);
569}
570
571/// ParseNonTypeTemplateParameter - Handle the parsing of non-type
572/// template parameters (e.g., in "template<int Size> class array;").
573///
574///       template-parameter:
575///         ...
576///         parameter-declaration
577Decl *
578Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
579  SourceLocation StartLoc = Tok.getLocation();
580
581  // Parse the declaration-specifiers (i.e., the type).
582  // FIXME: The type should probably be restricted in some way... Not all
583  // declarators (parts of declarators?) are accepted for parameters.
584  DeclSpec DS;
585  ParseDeclarationSpecifiers(DS);
586
587  // Parse this as a typename.
588  Declarator ParamDecl(DS, Declarator::TemplateParamContext);
589  ParseDeclarator(ParamDecl);
590  if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
591    // This probably shouldn't happen - and it's more of a Sema thing, but
592    // basically we didn't parse the type name because we couldn't associate
593    // it with an AST node. we should just skip to the comma or greater.
594    // TODO: This is currently a placeholder for some kind of Sema Error.
595    Diag(Tok.getLocation(), diag::err_parse_error);
596    SkipUntil(tok::comma, tok::greater, true, true);
597    return 0;
598  }
599
600  // If there is a default value, parse it.
601  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
602  // we introduce the template parameter into the local scope.
603  SourceLocation EqualLoc;
604  ExprResult DefaultArg;
605  if (Tok.is(tok::equal)) {
606    EqualLoc = ConsumeToken();
607
608    // C++ [temp.param]p15:
609    //   When parsing a default template-argument for a non-type
610    //   template-parameter, the first non-nested > is taken as the
611    //   end of the template-parameter-list rather than a greater-than
612    //   operator.
613    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
614
615    DefaultArg = ParseAssignmentExpression();
616    if (DefaultArg.isInvalid())
617      SkipUntil(tok::comma, tok::greater, true, true);
618  }
619
620  // Create the parameter.
621  return Actions.ActOnNonTypeTemplateParameter(getCurScope(), ParamDecl,
622                                               Depth, Position, EqualLoc,
623                                               DefaultArg.take());
624}
625
626/// \brief Parses a template-id that after the template name has
627/// already been parsed.
628///
629/// This routine takes care of parsing the enclosed template argument
630/// list ('<' template-parameter-list [opt] '>') and placing the
631/// results into a form that can be transferred to semantic analysis.
632///
633/// \param Template the template declaration produced by isTemplateName
634///
635/// \param TemplateNameLoc the source location of the template name
636///
637/// \param SS if non-NULL, the nested-name-specifier preceding the
638/// template name.
639///
640/// \param ConsumeLastToken if true, then we will consume the last
641/// token that forms the template-id. Otherwise, we will leave the
642/// last token in the stream (e.g., so that it can be replaced with an
643/// annotation token).
644bool
645Parser::ParseTemplateIdAfterTemplateName(TemplateTy Template,
646                                         SourceLocation TemplateNameLoc,
647                                         const CXXScopeSpec *SS,
648                                         bool ConsumeLastToken,
649                                         SourceLocation &LAngleLoc,
650                                         TemplateArgList &TemplateArgs,
651                                         SourceLocation &RAngleLoc) {
652  assert(Tok.is(tok::less) && "Must have already parsed the template-name");
653
654  // Consume the '<'.
655  LAngleLoc = ConsumeToken();
656
657  // Parse the optional template-argument-list.
658  bool Invalid = false;
659  {
660    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
661    if (Tok.isNot(tok::greater))
662      Invalid = ParseTemplateArgumentList(TemplateArgs);
663
664    if (Invalid) {
665      // Try to find the closing '>'.
666      SkipUntil(tok::greater, true, !ConsumeLastToken);
667
668      return true;
669    }
670  }
671
672  if (Tok.isNot(tok::greater) && Tok.isNot(tok::greatergreater)) {
673    Diag(Tok.getLocation(), diag::err_expected_greater);
674    return true;
675  }
676
677  // Determine the location of the '>' or '>>'. Only consume this
678  // token if the caller asked us to.
679  RAngleLoc = Tok.getLocation();
680
681  if (Tok.is(tok::greatergreater)) {
682    if (!getLang().CPlusPlus0x) {
683      const char *ReplaceStr = "> >";
684      if (NextToken().is(tok::greater) || NextToken().is(tok::greatergreater))
685        ReplaceStr = "> > ";
686
687      Diag(Tok.getLocation(), diag::err_two_right_angle_brackets_need_space)
688        << FixItHint::CreateReplacement(
689                                 SourceRange(Tok.getLocation()), ReplaceStr);
690    }
691
692    Tok.setKind(tok::greater);
693    if (!ConsumeLastToken) {
694      // Since we're not supposed to consume the '>>' token, we need
695      // to insert a second '>' token after the first.
696      PP.EnterToken(Tok);
697    }
698  } else if (ConsumeLastToken)
699    ConsumeToken();
700
701  return false;
702}
703
704/// \brief Replace the tokens that form a simple-template-id with an
705/// annotation token containing the complete template-id.
706///
707/// The first token in the stream must be the name of a template that
708/// is followed by a '<'. This routine will parse the complete
709/// simple-template-id and replace the tokens with a single annotation
710/// token with one of two different kinds: if the template-id names a
711/// type (and \p AllowTypeAnnotation is true), the annotation token is
712/// a type annotation that includes the optional nested-name-specifier
713/// (\p SS). Otherwise, the annotation token is a template-id
714/// annotation that does not include the optional
715/// nested-name-specifier.
716///
717/// \param Template  the declaration of the template named by the first
718/// token (an identifier), as returned from \c Action::isTemplateName().
719///
720/// \param TemplateNameKind the kind of template that \p Template
721/// refers to, as returned from \c Action::isTemplateName().
722///
723/// \param SS if non-NULL, the nested-name-specifier that precedes
724/// this template name.
725///
726/// \param TemplateKWLoc if valid, specifies that this template-id
727/// annotation was preceded by the 'template' keyword and gives the
728/// location of that keyword. If invalid (the default), then this
729/// template-id was not preceded by a 'template' keyword.
730///
731/// \param AllowTypeAnnotation if true (the default), then a
732/// simple-template-id that refers to a class template, template
733/// template parameter, or other template that produces a type will be
734/// replaced with a type annotation token. Otherwise, the
735/// simple-template-id is always replaced with a template-id
736/// annotation token.
737///
738/// If an unrecoverable parse error occurs and no annotation token can be
739/// formed, this function returns true.
740///
741bool Parser::AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
742                                     const CXXScopeSpec *SS,
743                                     UnqualifiedId &TemplateName,
744                                     SourceLocation TemplateKWLoc,
745                                     bool AllowTypeAnnotation) {
746  assert(getLang().CPlusPlus && "Can only annotate template-ids in C++");
747  assert(Template && Tok.is(tok::less) &&
748         "Parser isn't at the beginning of a template-id");
749
750  // Consume the template-name.
751  SourceLocation TemplateNameLoc = TemplateName.getSourceRange().getBegin();
752
753  // Parse the enclosed template argument list.
754  SourceLocation LAngleLoc, RAngleLoc;
755  TemplateArgList TemplateArgs;
756  bool Invalid = ParseTemplateIdAfterTemplateName(Template,
757                                                  TemplateNameLoc,
758                                                  SS, false, LAngleLoc,
759                                                  TemplateArgs,
760                                                  RAngleLoc);
761
762  if (Invalid) {
763    // If we failed to parse the template ID but skipped ahead to a >, we're not
764    // going to be able to form a token annotation.  Eat the '>' if present.
765    if (Tok.is(tok::greater))
766      ConsumeToken();
767    return true;
768  }
769
770  ASTTemplateArgsPtr TemplateArgsPtr(Actions, TemplateArgs.data(),
771                                     TemplateArgs.size());
772
773  // Build the annotation token.
774  if (TNK == TNK_Type_template && AllowTypeAnnotation) {
775    TypeResult Type
776      = Actions.ActOnTemplateIdType(Template, TemplateNameLoc,
777                                    LAngleLoc, TemplateArgsPtr,
778                                    RAngleLoc);
779    if (Type.isInvalid()) {
780      // If we failed to parse the template ID but skipped ahead to a >, we're not
781      // going to be able to form a token annotation.  Eat the '>' if present.
782      if (Tok.is(tok::greater))
783        ConsumeToken();
784      return true;
785    }
786
787    Tok.setKind(tok::annot_typename);
788    setTypeAnnotation(Tok, Type.get());
789    if (SS && SS->isNotEmpty())
790      Tok.setLocation(SS->getBeginLoc());
791    else if (TemplateKWLoc.isValid())
792      Tok.setLocation(TemplateKWLoc);
793    else
794      Tok.setLocation(TemplateNameLoc);
795  } else {
796    // Build a template-id annotation token that can be processed
797    // later.
798    Tok.setKind(tok::annot_template_id);
799    TemplateIdAnnotation *TemplateId
800      = TemplateIdAnnotation::Allocate(TemplateArgs.size());
801    TemplateId->TemplateNameLoc = TemplateNameLoc;
802    if (TemplateName.getKind() == UnqualifiedId::IK_Identifier) {
803      TemplateId->Name = TemplateName.Identifier;
804      TemplateId->Operator = OO_None;
805    } else {
806      TemplateId->Name = 0;
807      TemplateId->Operator = TemplateName.OperatorFunctionId.Operator;
808    }
809    TemplateId->Template = Template;
810    TemplateId->Kind = TNK;
811    TemplateId->LAngleLoc = LAngleLoc;
812    TemplateId->RAngleLoc = RAngleLoc;
813    ParsedTemplateArgument *Args = TemplateId->getTemplateArgs();
814    for (unsigned Arg = 0, ArgEnd = TemplateArgs.size(); Arg != ArgEnd; ++Arg)
815      Args[Arg] = TemplateArgs[Arg];
816    Tok.setAnnotationValue(TemplateId);
817    if (TemplateKWLoc.isValid())
818      Tok.setLocation(TemplateKWLoc);
819    else
820      Tok.setLocation(TemplateNameLoc);
821
822    TemplateArgsPtr.release();
823  }
824
825  // Common fields for the annotation token
826  Tok.setAnnotationEndLoc(RAngleLoc);
827
828  // In case the tokens were cached, have Preprocessor replace them with the
829  // annotation token.
830  PP.AnnotateCachedTokens(Tok);
831  return false;
832}
833
834/// \brief Replaces a template-id annotation token with a type
835/// annotation token.
836///
837/// If there was a failure when forming the type from the template-id,
838/// a type annotation token will still be created, but will have a
839/// NULL type pointer to signify an error.
840void Parser::AnnotateTemplateIdTokenAsType(const CXXScopeSpec *SS) {
841  assert(Tok.is(tok::annot_template_id) && "Requires template-id tokens");
842
843  TemplateIdAnnotation *TemplateId
844    = static_cast<TemplateIdAnnotation *>(Tok.getAnnotationValue());
845  assert((TemplateId->Kind == TNK_Type_template ||
846          TemplateId->Kind == TNK_Dependent_template_name) &&
847         "Only works for type and dependent templates");
848
849  ASTTemplateArgsPtr TemplateArgsPtr(Actions,
850                                     TemplateId->getTemplateArgs(),
851                                     TemplateId->NumArgs);
852
853  TypeResult Type
854    = Actions.ActOnTemplateIdType(TemplateId->Template,
855                                  TemplateId->TemplateNameLoc,
856                                  TemplateId->LAngleLoc,
857                                  TemplateArgsPtr,
858                                  TemplateId->RAngleLoc);
859  // Create the new "type" annotation token.
860  Tok.setKind(tok::annot_typename);
861  setTypeAnnotation(Tok, Type.isInvalid() ? ParsedType() : Type.get());
862  if (SS && SS->isNotEmpty()) // it was a C++ qualified type name.
863    Tok.setLocation(SS->getBeginLoc());
864  // End location stays the same
865
866  // Replace the template-id annotation token, and possible the scope-specifier
867  // that precedes it, with the typename annotation token.
868  PP.AnnotateCachedTokens(Tok);
869  TemplateId->Destroy();
870}
871
872/// \brief Determine whether the given token can end a template argument.
873static bool isEndOfTemplateArgument(Token Tok) {
874  return Tok.is(tok::comma) || Tok.is(tok::greater) ||
875         Tok.is(tok::greatergreater);
876}
877
878/// \brief Parse a C++ template template argument.
879ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
880  if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
881      !Tok.is(tok::annot_cxxscope))
882    return ParsedTemplateArgument();
883
884  // C++0x [temp.arg.template]p1:
885  //   A template-argument for a template template-parameter shall be the name
886  //   of a class template or a template alias, expressed as id-expression.
887  //
888  // We parse an id-expression that refers to a class template or template
889  // alias. The grammar we parse is:
890  //
891  //   nested-name-specifier[opt] template[opt] identifier
892  //
893  // followed by a token that terminates a template argument, such as ',',
894  // '>', or (in some cases) '>>'.
895  CXXScopeSpec SS; // nested-name-specifier, if present
896  ParseOptionalCXXScopeSpecifier(SS, ParsedType(),
897                                 /*EnteringContext=*/false);
898
899  if (SS.isSet() && Tok.is(tok::kw_template)) {
900    // Parse the optional 'template' keyword following the
901    // nested-name-specifier.
902    SourceLocation TemplateLoc = ConsumeToken();
903
904    if (Tok.is(tok::identifier)) {
905      // We appear to have a dependent template name.
906      UnqualifiedId Name;
907      Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
908      ConsumeToken(); // the identifier
909
910      // If the next token signals the end of a template argument,
911      // then we have a dependent template name that could be a template
912      // template argument.
913      TemplateTy Template;
914      if (isEndOfTemplateArgument(Tok) &&
915          Actions.ActOnDependentTemplateName(getCurScope(), TemplateLoc,
916                                             SS, Name,
917                                             /*ObjectType=*/ ParsedType(),
918                                             /*EnteringContext=*/false,
919                                             Template))
920        return ParsedTemplateArgument(SS, Template, Name.StartLocation);
921    }
922  } else if (Tok.is(tok::identifier)) {
923    // We may have a (non-dependent) template name.
924    TemplateTy Template;
925    UnqualifiedId Name;
926    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
927    ConsumeToken(); // the identifier
928
929    if (isEndOfTemplateArgument(Tok)) {
930      bool MemberOfUnknownSpecialization;
931      TemplateNameKind TNK = Actions.isTemplateName(getCurScope(), SS,
932                                               /*hasTemplateKeyword=*/false,
933                                                    Name,
934                                               /*ObjectType=*/ ParsedType(),
935                                                    /*EnteringContext=*/false,
936                                                    Template,
937                                                MemberOfUnknownSpecialization);
938      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
939        // We have an id-expression that refers to a class template or
940        // (C++0x) template alias.
941        return ParsedTemplateArgument(SS, Template, Name.StartLocation);
942      }
943    }
944  }
945
946  // We don't have a template template argument.
947  return ParsedTemplateArgument();
948}
949
950/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
951///
952///       template-argument: [C++ 14.2]
953///         constant-expression
954///         type-id
955///         id-expression
956ParsedTemplateArgument Parser::ParseTemplateArgument() {
957  // C++ [temp.arg]p2:
958  //   In a template-argument, an ambiguity between a type-id and an
959  //   expression is resolved to a type-id, regardless of the form of
960  //   the corresponding template-parameter.
961  //
962  // Therefore, we initially try to parse a type-id.
963  if (isCXXTypeId(TypeIdAsTemplateArgument)) {
964    SourceLocation Loc = Tok.getLocation();
965    TypeResult TypeArg = ParseTypeName();
966    if (TypeArg.isInvalid())
967      return ParsedTemplateArgument();
968
969    return ParsedTemplateArgument(ParsedTemplateArgument::Type,
970                                  TypeArg.get().getAsOpaquePtr(),
971                                  Loc);
972  }
973
974  // Try to parse a template template argument.
975  {
976    TentativeParsingAction TPA(*this);
977
978    ParsedTemplateArgument TemplateTemplateArgument
979      = ParseTemplateTemplateArgument();
980    if (!TemplateTemplateArgument.isInvalid()) {
981      TPA.Commit();
982      return TemplateTemplateArgument;
983    }
984
985    // Revert this tentative parse to parse a non-type template argument.
986    TPA.Revert();
987  }
988
989  // Parse a non-type template argument.
990  SourceLocation Loc = Tok.getLocation();
991  ExprResult ExprArg = ParseConstantExpression();
992  if (ExprArg.isInvalid() || !ExprArg.get())
993    return ParsedTemplateArgument();
994
995  return ParsedTemplateArgument(ParsedTemplateArgument::NonType,
996                                ExprArg.release(), Loc);
997}
998
999/// \brief Determine whether the current tokens can only be parsed as a
1000/// template argument list (starting with the '<') and never as a '<'
1001/// expression.
1002bool Parser::IsTemplateArgumentList(unsigned Skip) {
1003  struct AlwaysRevertAction : TentativeParsingAction {
1004    AlwaysRevertAction(Parser &P) : TentativeParsingAction(P) { }
1005    ~AlwaysRevertAction() { Revert(); }
1006  } Tentative(*this);
1007
1008  while (Skip) {
1009    ConsumeToken();
1010    --Skip;
1011  }
1012
1013  // '<'
1014  if (!Tok.is(tok::less))
1015    return false;
1016  ConsumeToken();
1017
1018  // An empty template argument list.
1019  if (Tok.is(tok::greater))
1020    return true;
1021
1022  // See whether we have declaration specifiers, which indicate a type.
1023  while (isCXXDeclarationSpecifier() == TPResult::True())
1024    ConsumeToken();
1025
1026  // If we have a '>' or a ',' then this is a template argument list.
1027  return Tok.is(tok::greater) || Tok.is(tok::comma);
1028}
1029
1030/// ParseTemplateArgumentList - Parse a C++ template-argument-list
1031/// (C++ [temp.names]). Returns true if there was an error.
1032///
1033///       template-argument-list: [C++ 14.2]
1034///         template-argument
1035///         template-argument-list ',' template-argument
1036bool
1037Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs) {
1038  while (true) {
1039    ParsedTemplateArgument Arg = ParseTemplateArgument();
1040    if (Arg.isInvalid()) {
1041      SkipUntil(tok::comma, tok::greater, true, true);
1042      return true;
1043    }
1044
1045    // Save this template argument.
1046    TemplateArgs.push_back(Arg);
1047
1048    // If the next token is a comma, consume it and keep reading
1049    // arguments.
1050    if (Tok.isNot(tok::comma)) break;
1051
1052    // Consume the comma.
1053    ConsumeToken();
1054  }
1055
1056  return false;
1057}
1058
1059/// \brief Parse a C++ explicit template instantiation
1060/// (C++ [temp.explicit]).
1061///
1062///       explicit-instantiation:
1063///         'extern' [opt] 'template' declaration
1064///
1065/// Note that the 'extern' is a GNU extension and C++0x feature.
1066Decl *Parser::ParseExplicitInstantiation(SourceLocation ExternLoc,
1067                                         SourceLocation TemplateLoc,
1068                                         SourceLocation &DeclEnd) {
1069  // This isn't really required here.
1070  ParsingDeclRAIIObject ParsingTemplateParams(*this);
1071
1072  return ParseSingleDeclarationAfterTemplate(Declarator::FileContext,
1073                                             ParsedTemplateInfo(ExternLoc,
1074                                                                TemplateLoc),
1075                                             ParsingTemplateParams,
1076                                             DeclEnd, AS_none);
1077}
1078