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  1. //===- IdentifierTable.h - Hash table for identifier lookup -----*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. /// \file
  10. /// Defines the clang::IdentifierInfo, clang::IdentifierTable, and
  11. /// clang::Selector interfaces.
  12. //
  13. //===----------------------------------------------------------------------===//
  14.  
  15. #ifndef LLVM_CLANG_BASIC_IDENTIFIERTABLE_H
  16. #define LLVM_CLANG_BASIC_IDENTIFIERTABLE_H
  17.  
  18. #include "clang/Basic/DiagnosticIDs.h"
  19. #include "clang/Basic/LLVM.h"
  20. #include "clang/Basic/TokenKinds.h"
  21. #include "llvm/ADT/DenseMapInfo.h"
  22. #include "llvm/ADT/SmallString.h"
  23. #include "llvm/ADT/StringMap.h"
  24. #include "llvm/ADT/StringRef.h"
  25. #include "llvm/Support/Allocator.h"
  26. #include "llvm/Support/PointerLikeTypeTraits.h"
  27. #include "llvm/Support/type_traits.h"
  28. #include <cassert>
  29. #include <cstddef>
  30. #include <cstdint>
  31. #include <cstring>
  32. #include <string>
  33. #include <utility>
  34.  
  35. namespace clang {
  36.  
  37. class DeclarationName;
  38. class DeclarationNameTable;
  39. class IdentifierInfo;
  40. class LangOptions;
  41. class MultiKeywordSelector;
  42. class SourceLocation;
  43.  
  44. enum class ReservedIdentifierStatus {
  45.   NotReserved = 0,
  46.   StartsWithUnderscoreAtGlobalScope,
  47.   StartsWithUnderscoreAndIsExternC,
  48.   StartsWithDoubleUnderscore,
  49.   StartsWithUnderscoreFollowedByCapitalLetter,
  50.   ContainsDoubleUnderscore,
  51. };
  52.  
  53. /// Determine whether an identifier is reserved for use as a name at global
  54. /// scope. Such identifiers might be implementation-specific global functions
  55. /// or variables.
  56. inline bool isReservedAtGlobalScope(ReservedIdentifierStatus Status) {
  57.   return Status != ReservedIdentifierStatus::NotReserved;
  58. }
  59.  
  60. /// Determine whether an identifier is reserved in all contexts. Such
  61. /// identifiers might be implementation-specific keywords or macros, for
  62. /// example.
  63. inline bool isReservedInAllContexts(ReservedIdentifierStatus Status) {
  64.   return Status != ReservedIdentifierStatus::NotReserved &&
  65.          Status != ReservedIdentifierStatus::StartsWithUnderscoreAtGlobalScope &&
  66.          Status != ReservedIdentifierStatus::StartsWithUnderscoreAndIsExternC;
  67. }
  68.  
  69. /// A simple pair of identifier info and location.
  70. using IdentifierLocPair = std::pair<IdentifierInfo *, SourceLocation>;
  71.  
  72. /// IdentifierInfo and other related classes are aligned to
  73. /// 8 bytes so that DeclarationName can use the lower 3 bits
  74. /// of a pointer to one of these classes.
  75. enum { IdentifierInfoAlignment = 8 };
  76.  
  77. static constexpr int ObjCOrBuiltinIDBits = 16;
  78.  
  79. /// One of these records is kept for each identifier that
  80. /// is lexed.  This contains information about whether the token was \#define'd,
  81. /// is a language keyword, or if it is a front-end token of some sort (e.g. a
  82. /// variable or function name).  The preprocessor keeps this information in a
  83. /// set, and all tok::identifier tokens have a pointer to one of these.
  84. /// It is aligned to 8 bytes because DeclarationName needs the lower 3 bits.
  85. class alignas(IdentifierInfoAlignment) IdentifierInfo {
  86.   friend class IdentifierTable;
  87.  
  88.   // Front-end token ID or tok::identifier.
  89.   unsigned TokenID : 9;
  90.  
  91.   // ObjC keyword ('protocol' in '@protocol') or builtin (__builtin_inf).
  92.   // First NUM_OBJC_KEYWORDS values are for Objective-C,
  93.   // the remaining values are for builtins.
  94.   unsigned ObjCOrBuiltinID : ObjCOrBuiltinIDBits;
  95.  
  96.   // True if there is a #define for this.
  97.   unsigned HasMacro : 1;
  98.  
  99.   // True if there was a #define for this.
  100.   unsigned HadMacro : 1;
  101.  
  102.   // True if the identifier is a language extension.
  103.   unsigned IsExtension : 1;
  104.  
  105.   // True if the identifier is a keyword in a newer or proposed Standard.
  106.   unsigned IsFutureCompatKeyword : 1;
  107.  
  108.   // True if the identifier is poisoned.
  109.   unsigned IsPoisoned : 1;
  110.  
  111.   // True if the identifier is a C++ operator keyword.
  112.   unsigned IsCPPOperatorKeyword : 1;
  113.  
  114.   // Internal bit set by the member function RecomputeNeedsHandleIdentifier.
  115.   // See comment about RecomputeNeedsHandleIdentifier for more info.
  116.   unsigned NeedsHandleIdentifier : 1;
  117.  
  118.   // True if the identifier was loaded (at least partially) from an AST file.
  119.   unsigned IsFromAST : 1;
  120.  
  121.   // True if the identifier has changed from the definition
  122.   // loaded from an AST file.
  123.   unsigned ChangedAfterLoad : 1;
  124.  
  125.   // True if the identifier's frontend information has changed from the
  126.   // definition loaded from an AST file.
  127.   unsigned FEChangedAfterLoad : 1;
  128.  
  129.   // True if revertTokenIDToIdentifier was called.
  130.   unsigned RevertedTokenID : 1;
  131.  
  132.   // True if there may be additional information about
  133.   // this identifier stored externally.
  134.   unsigned OutOfDate : 1;
  135.  
  136.   // True if this is the 'import' contextual keyword.
  137.   unsigned IsModulesImport : 1;
  138.  
  139.   // True if this is a mangled OpenMP variant name.
  140.   unsigned IsMangledOpenMPVariantName : 1;
  141.  
  142.   // True if this is a deprecated macro.
  143.   unsigned IsDeprecatedMacro : 1;
  144.  
  145.   // True if this macro is unsafe in headers.
  146.   unsigned IsRestrictExpansion : 1;
  147.  
  148.   // True if this macro is final.
  149.   unsigned IsFinal : 1;
  150.  
  151.   // 22 bits left in a 64-bit word.
  152.  
  153.   // Managed by the language front-end.
  154.   void *FETokenInfo = nullptr;
  155.  
  156.   llvm::StringMapEntry<IdentifierInfo *> *Entry = nullptr;
  157.  
  158.   IdentifierInfo()
  159.       : TokenID(tok::identifier), ObjCOrBuiltinID(0), HasMacro(false),
  160.         HadMacro(false), IsExtension(false), IsFutureCompatKeyword(false),
  161.         IsPoisoned(false), IsCPPOperatorKeyword(false),
  162.         NeedsHandleIdentifier(false), IsFromAST(false), ChangedAfterLoad(false),
  163.         FEChangedAfterLoad(false), RevertedTokenID(false), OutOfDate(false),
  164.         IsModulesImport(false), IsMangledOpenMPVariantName(false),
  165.         IsDeprecatedMacro(false), IsRestrictExpansion(false), IsFinal(false) {}
  166.  
  167. public:
  168.   IdentifierInfo(const IdentifierInfo &) = delete;
  169.   IdentifierInfo &operator=(const IdentifierInfo &) = delete;
  170.   IdentifierInfo(IdentifierInfo &&) = delete;
  171.   IdentifierInfo &operator=(IdentifierInfo &&) = delete;
  172.  
  173.   /// Return true if this is the identifier for the specified string.
  174.   ///
  175.   /// This is intended to be used for string literals only: II->isStr("foo").
  176.   template <std::size_t StrLen>
  177.   bool isStr(const char (&Str)[StrLen]) const {
  178.     return getLength() == StrLen-1 &&
  179.            memcmp(getNameStart(), Str, StrLen-1) == 0;
  180.   }
  181.  
  182.   /// Return true if this is the identifier for the specified StringRef.
  183.   bool isStr(llvm::StringRef Str) const {
  184.     llvm::StringRef ThisStr(getNameStart(), getLength());
  185.     return ThisStr == Str;
  186.   }
  187.  
  188.   /// Return the beginning of the actual null-terminated string for this
  189.   /// identifier.
  190.   const char *getNameStart() const { return Entry->getKeyData(); }
  191.  
  192.   /// Efficiently return the length of this identifier info.
  193.   unsigned getLength() const { return Entry->getKeyLength(); }
  194.  
  195.   /// Return the actual identifier string.
  196.   StringRef getName() const {
  197.     return StringRef(getNameStart(), getLength());
  198.   }
  199.  
  200.   /// Return true if this identifier is \#defined to some other value.
  201.   /// \note The current definition may be in a module and not currently visible.
  202.   bool hasMacroDefinition() const {
  203.     return HasMacro;
  204.   }
  205.   void setHasMacroDefinition(bool Val) {
  206.     if (HasMacro == Val) return;
  207.  
  208.     HasMacro = Val;
  209.     if (Val) {
  210.       NeedsHandleIdentifier = true;
  211.       HadMacro = true;
  212.     } else {
  213.       // If this is a final macro, make the deprecation and header unsafe bits
  214.       // stick around after the undefinition so they apply to any redefinitions.
  215.       if (!IsFinal) {
  216.         // Because calling the setters of these calls recomputes, just set them
  217.         // manually to avoid recomputing a bunch of times.
  218.         IsDeprecatedMacro = false;
  219.         IsRestrictExpansion = false;
  220.       }
  221.       RecomputeNeedsHandleIdentifier();
  222.     }
  223.   }
  224.   /// Returns true if this identifier was \#defined to some value at any
  225.   /// moment. In this case there should be an entry for the identifier in the
  226.   /// macro history table in Preprocessor.
  227.   bool hadMacroDefinition() const {
  228.     return HadMacro;
  229.   }
  230.  
  231.   bool isDeprecatedMacro() const { return IsDeprecatedMacro; }
  232.  
  233.   void setIsDeprecatedMacro(bool Val) {
  234.     if (IsDeprecatedMacro == Val)
  235.       return;
  236.     IsDeprecatedMacro = Val;
  237.     if (Val)
  238.       NeedsHandleIdentifier = true;
  239.     else
  240.       RecomputeNeedsHandleIdentifier();
  241.   }
  242.  
  243.   bool isRestrictExpansion() const { return IsRestrictExpansion; }
  244.  
  245.   void setIsRestrictExpansion(bool Val) {
  246.     if (IsRestrictExpansion == Val)
  247.       return;
  248.     IsRestrictExpansion = Val;
  249.     if (Val)
  250.       NeedsHandleIdentifier = true;
  251.     else
  252.       RecomputeNeedsHandleIdentifier();
  253.   }
  254.  
  255.   bool isFinal() const { return IsFinal; }
  256.  
  257.   void setIsFinal(bool Val) { IsFinal = Val; }
  258.  
  259.   /// If this is a source-language token (e.g. 'for'), this API
  260.   /// can be used to cause the lexer to map identifiers to source-language
  261.   /// tokens.
  262.   tok::TokenKind getTokenID() const { return (tok::TokenKind)TokenID; }
  263.  
  264.   /// True if revertTokenIDToIdentifier() was called.
  265.   bool hasRevertedTokenIDToIdentifier() const { return RevertedTokenID; }
  266.  
  267.   /// Revert TokenID to tok::identifier; used for GNU libstdc++ 4.2
  268.   /// compatibility.
  269.   ///
  270.   /// TokenID is normally read-only but there are 2 instances where we revert it
  271.   /// to tok::identifier for libstdc++ 4.2. Keep track of when this happens
  272.   /// using this method so we can inform serialization about it.
  273.   void revertTokenIDToIdentifier() {
  274.     assert(TokenID != tok::identifier && "Already at tok::identifier");
  275.     TokenID = tok::identifier;
  276.     RevertedTokenID = true;
  277.   }
  278.   void revertIdentifierToTokenID(tok::TokenKind TK) {
  279.     assert(TokenID == tok::identifier && "Should be at tok::identifier");
  280.     TokenID = TK;
  281.     RevertedTokenID = false;
  282.   }
  283.  
  284.   /// Return the preprocessor keyword ID for this identifier.
  285.   ///
  286.   /// For example, "define" will return tok::pp_define.
  287.   tok::PPKeywordKind getPPKeywordID() const;
  288.  
  289.   /// Return the Objective-C keyword ID for the this identifier.
  290.   ///
  291.   /// For example, 'class' will return tok::objc_class if ObjC is enabled.
  292.   tok::ObjCKeywordKind getObjCKeywordID() const {
  293.     if (ObjCOrBuiltinID < tok::NUM_OBJC_KEYWORDS)
  294.       return tok::ObjCKeywordKind(ObjCOrBuiltinID);
  295.     else
  296.       return tok::objc_not_keyword;
  297.   }
  298.   void setObjCKeywordID(tok::ObjCKeywordKind ID) { ObjCOrBuiltinID = ID; }
  299.  
  300.   /// Return a value indicating whether this is a builtin function.
  301.   ///
  302.   /// 0 is not-built-in. 1+ are specific builtin functions.
  303.   unsigned getBuiltinID() const {
  304.     if (ObjCOrBuiltinID >= tok::NUM_OBJC_KEYWORDS)
  305.       return ObjCOrBuiltinID - tok::NUM_OBJC_KEYWORDS;
  306.     else
  307.       return 0;
  308.   }
  309.   void setBuiltinID(unsigned ID) {
  310.     ObjCOrBuiltinID = ID + tok::NUM_OBJC_KEYWORDS;
  311.     assert(ObjCOrBuiltinID - unsigned(tok::NUM_OBJC_KEYWORDS) == ID
  312.            && "ID too large for field!");
  313.   }
  314.  
  315.   unsigned getObjCOrBuiltinID() const { return ObjCOrBuiltinID; }
  316.   void setObjCOrBuiltinID(unsigned ID) { ObjCOrBuiltinID = ID; }
  317.  
  318.   /// get/setExtension - Initialize information about whether or not this
  319.   /// language token is an extension.  This controls extension warnings, and is
  320.   /// only valid if a custom token ID is set.
  321.   bool isExtensionToken() const { return IsExtension; }
  322.   void setIsExtensionToken(bool Val) {
  323.     IsExtension = Val;
  324.     if (Val)
  325.       NeedsHandleIdentifier = true;
  326.     else
  327.       RecomputeNeedsHandleIdentifier();
  328.   }
  329.  
  330.   /// is/setIsFutureCompatKeyword - Initialize information about whether or not
  331.   /// this language token is a keyword in a newer or proposed Standard. This
  332.   /// controls compatibility warnings, and is only true when not parsing the
  333.   /// corresponding Standard. Once a compatibility problem has been diagnosed
  334.   /// with this keyword, the flag will be cleared.
  335.   bool isFutureCompatKeyword() const { return IsFutureCompatKeyword; }
  336.   void setIsFutureCompatKeyword(bool Val) {
  337.     IsFutureCompatKeyword = Val;
  338.     if (Val)
  339.       NeedsHandleIdentifier = true;
  340.     else
  341.       RecomputeNeedsHandleIdentifier();
  342.   }
  343.  
  344.   /// setIsPoisoned - Mark this identifier as poisoned.  After poisoning, the
  345.   /// Preprocessor will emit an error every time this token is used.
  346.   void setIsPoisoned(bool Value = true) {
  347.     IsPoisoned = Value;
  348.     if (Value)
  349.       NeedsHandleIdentifier = true;
  350.     else
  351.       RecomputeNeedsHandleIdentifier();
  352.   }
  353.  
  354.   /// Return true if this token has been poisoned.
  355.   bool isPoisoned() const { return IsPoisoned; }
  356.  
  357.   /// isCPlusPlusOperatorKeyword/setIsCPlusPlusOperatorKeyword controls whether
  358.   /// this identifier is a C++ alternate representation of an operator.
  359.   void setIsCPlusPlusOperatorKeyword(bool Val = true) {
  360.     IsCPPOperatorKeyword = Val;
  361.   }
  362.   bool isCPlusPlusOperatorKeyword() const { return IsCPPOperatorKeyword; }
  363.  
  364.   /// Return true if this token is a keyword in the specified language.
  365.   bool isKeyword(const LangOptions &LangOpts) const;
  366.  
  367.   /// Return true if this token is a C++ keyword in the specified
  368.   /// language.
  369.   bool isCPlusPlusKeyword(const LangOptions &LangOpts) const;
  370.  
  371.   /// Get and set FETokenInfo. The language front-end is allowed to associate
  372.   /// arbitrary metadata with this token.
  373.   void *getFETokenInfo() const { return FETokenInfo; }
  374.   void setFETokenInfo(void *T) { FETokenInfo = T; }
  375.  
  376.   /// Return true if the Preprocessor::HandleIdentifier must be called
  377.   /// on a token of this identifier.
  378.   ///
  379.   /// If this returns false, we know that HandleIdentifier will not affect
  380.   /// the token.
  381.   bool isHandleIdentifierCase() const { return NeedsHandleIdentifier; }
  382.  
  383.   /// Return true if the identifier in its current state was loaded
  384.   /// from an AST file.
  385.   bool isFromAST() const { return IsFromAST; }
  386.  
  387.   void setIsFromAST() { IsFromAST = true; }
  388.  
  389.   /// Determine whether this identifier has changed since it was loaded
  390.   /// from an AST file.
  391.   bool hasChangedSinceDeserialization() const {
  392.     return ChangedAfterLoad;
  393.   }
  394.  
  395.   /// Note that this identifier has changed since it was loaded from
  396.   /// an AST file.
  397.   void setChangedSinceDeserialization() {
  398.     ChangedAfterLoad = true;
  399.   }
  400.  
  401.   /// Determine whether the frontend token information for this
  402.   /// identifier has changed since it was loaded from an AST file.
  403.   bool hasFETokenInfoChangedSinceDeserialization() const {
  404.     return FEChangedAfterLoad;
  405.   }
  406.  
  407.   /// Note that the frontend token information for this identifier has
  408.   /// changed since it was loaded from an AST file.
  409.   void setFETokenInfoChangedSinceDeserialization() {
  410.     FEChangedAfterLoad = true;
  411.   }
  412.  
  413.   /// Determine whether the information for this identifier is out of
  414.   /// date with respect to the external source.
  415.   bool isOutOfDate() const { return OutOfDate; }
  416.  
  417.   /// Set whether the information for this identifier is out of
  418.   /// date with respect to the external source.
  419.   void setOutOfDate(bool OOD) {
  420.     OutOfDate = OOD;
  421.     if (OOD)
  422.       NeedsHandleIdentifier = true;
  423.     else
  424.       RecomputeNeedsHandleIdentifier();
  425.   }
  426.  
  427.   /// Determine whether this is the contextual keyword \c import.
  428.   bool isModulesImport() const { return IsModulesImport; }
  429.  
  430.   /// Set whether this identifier is the contextual keyword \c import.
  431.   void setModulesImport(bool I) {
  432.     IsModulesImport = I;
  433.     if (I)
  434.       NeedsHandleIdentifier = true;
  435.     else
  436.       RecomputeNeedsHandleIdentifier();
  437.   }
  438.  
  439.   /// Determine whether this is the mangled name of an OpenMP variant.
  440.   bool isMangledOpenMPVariantName() const { return IsMangledOpenMPVariantName; }
  441.  
  442.   /// Set whether this is the mangled name of an OpenMP variant.
  443.   void setMangledOpenMPVariantName(bool I) { IsMangledOpenMPVariantName = I; }
  444.  
  445.   /// Return true if this identifier is an editor placeholder.
  446.   ///
  447.   /// Editor placeholders are produced by the code-completion engine and are
  448.   /// represented as characters between '<#' and '#>' in the source code. An
  449.   /// example of auto-completed call with a placeholder parameter is shown
  450.   /// below:
  451.   /// \code
  452.   ///   function(<#int x#>);
  453.   /// \endcode
  454.   bool isEditorPlaceholder() const {
  455.     return getName().startswith("<#") && getName().endswith("#>");
  456.   }
  457.  
  458.   /// Determine whether \p this is a name reserved for the implementation (C99
  459.   /// 7.1.3, C++ [lib.global.names]).
  460.   ReservedIdentifierStatus isReserved(const LangOptions &LangOpts) const;
  461.  
  462.   /// If the identifier is an "uglified" reserved name, return a cleaned form.
  463.   /// e.g. _Foo => Foo. Otherwise, just returns the name.
  464.   StringRef deuglifiedName() const;
  465.  
  466.   /// Provide less than operator for lexicographical sorting.
  467.   bool operator<(const IdentifierInfo &RHS) const {
  468.     return getName() < RHS.getName();
  469.   }
  470.  
  471. private:
  472.   /// The Preprocessor::HandleIdentifier does several special (but rare)
  473.   /// things to identifiers of various sorts.  For example, it changes the
  474.   /// \c for keyword token from tok::identifier to tok::for.
  475.   ///
  476.   /// This method is very tied to the definition of HandleIdentifier.  Any
  477.   /// change to it should be reflected here.
  478.   void RecomputeNeedsHandleIdentifier() {
  479.     NeedsHandleIdentifier = isPoisoned() || hasMacroDefinition() ||
  480.                             isExtensionToken() || isFutureCompatKeyword() ||
  481.                             isOutOfDate() || isModulesImport();
  482.   }
  483. };
  484.  
  485. /// An RAII object for [un]poisoning an identifier within a scope.
  486. ///
  487. /// \p II is allowed to be null, in which case objects of this type have
  488. /// no effect.
  489. class PoisonIdentifierRAIIObject {
  490.   IdentifierInfo *const II;
  491.   const bool OldValue;
  492.  
  493. public:
  494.   PoisonIdentifierRAIIObject(IdentifierInfo *II, bool NewValue)
  495.     : II(II), OldValue(II ? II->isPoisoned() : false) {
  496.     if(II)
  497.       II->setIsPoisoned(NewValue);
  498.   }
  499.  
  500.   ~PoisonIdentifierRAIIObject() {
  501.     if(II)
  502.       II->setIsPoisoned(OldValue);
  503.   }
  504. };
  505.  
  506. /// An iterator that walks over all of the known identifiers
  507. /// in the lookup table.
  508. ///
  509. /// Since this iterator uses an abstract interface via virtual
  510. /// functions, it uses an object-oriented interface rather than the
  511. /// more standard C++ STL iterator interface. In this OO-style
  512. /// iteration, the single function \c Next() provides dereference,
  513. /// advance, and end-of-sequence checking in a single
  514. /// operation. Subclasses of this iterator type will provide the
  515. /// actual functionality.
  516. class IdentifierIterator {
  517. protected:
  518.   IdentifierIterator() = default;
  519.  
  520. public:
  521.   IdentifierIterator(const IdentifierIterator &) = delete;
  522.   IdentifierIterator &operator=(const IdentifierIterator &) = delete;
  523.  
  524.   virtual ~IdentifierIterator();
  525.  
  526.   /// Retrieve the next string in the identifier table and
  527.   /// advances the iterator for the following string.
  528.   ///
  529.   /// \returns The next string in the identifier table. If there is
  530.   /// no such string, returns an empty \c StringRef.
  531.   virtual StringRef Next() = 0;
  532. };
  533.  
  534. /// Provides lookups to, and iteration over, IdentiferInfo objects.
  535. class IdentifierInfoLookup {
  536. public:
  537.   virtual ~IdentifierInfoLookup();
  538.  
  539.   /// Return the IdentifierInfo for the specified named identifier.
  540.   ///
  541.   /// Unlike the version in IdentifierTable, this returns a pointer instead
  542.   /// of a reference.  If the pointer is null then the IdentifierInfo cannot
  543.   /// be found.
  544.   virtual IdentifierInfo* get(StringRef Name) = 0;
  545.  
  546.   /// Retrieve an iterator into the set of all identifiers
  547.   /// known to this identifier lookup source.
  548.   ///
  549.   /// This routine provides access to all of the identifiers known to
  550.   /// the identifier lookup, allowing access to the contents of the
  551.   /// identifiers without introducing the overhead of constructing
  552.   /// IdentifierInfo objects for each.
  553.   ///
  554.   /// \returns A new iterator into the set of known identifiers. The
  555.   /// caller is responsible for deleting this iterator.
  556.   virtual IdentifierIterator *getIdentifiers();
  557. };
  558.  
  559. /// Implements an efficient mapping from strings to IdentifierInfo nodes.
  560. ///
  561. /// This has no other purpose, but this is an extremely performance-critical
  562. /// piece of the code, as each occurrence of every identifier goes through
  563. /// here when lexed.
  564. class IdentifierTable {
  565.   // Shark shows that using MallocAllocator is *much* slower than using this
  566.   // BumpPtrAllocator!
  567.   using HashTableTy = llvm::StringMap<IdentifierInfo *, llvm::BumpPtrAllocator>;
  568.   HashTableTy HashTable;
  569.  
  570.   IdentifierInfoLookup* ExternalLookup;
  571.  
  572. public:
  573.   /// Create the identifier table.
  574.   explicit IdentifierTable(IdentifierInfoLookup *ExternalLookup = nullptr);
  575.  
  576.   /// Create the identifier table, populating it with info about the
  577.   /// language keywords for the language specified by \p LangOpts.
  578.   explicit IdentifierTable(const LangOptions &LangOpts,
  579.                            IdentifierInfoLookup *ExternalLookup = nullptr);
  580.  
  581.   /// Set the external identifier lookup mechanism.
  582.   void setExternalIdentifierLookup(IdentifierInfoLookup *IILookup) {
  583.     ExternalLookup = IILookup;
  584.   }
  585.  
  586.   /// Retrieve the external identifier lookup object, if any.
  587.   IdentifierInfoLookup *getExternalIdentifierLookup() const {
  588.     return ExternalLookup;
  589.   }
  590.  
  591.   llvm::BumpPtrAllocator& getAllocator() {
  592.     return HashTable.getAllocator();
  593.   }
  594.  
  595.   /// Return the identifier token info for the specified named
  596.   /// identifier.
  597.   IdentifierInfo &get(StringRef Name) {
  598.     auto &Entry = *HashTable.try_emplace(Name, nullptr).first;
  599.  
  600.     IdentifierInfo *&II = Entry.second;
  601.     if (II) return *II;
  602.  
  603.     // No entry; if we have an external lookup, look there first.
  604.     if (ExternalLookup) {
  605.       II = ExternalLookup->get(Name);
  606.       if (II)
  607.         return *II;
  608.     }
  609.  
  610.     // Lookups failed, make a new IdentifierInfo.
  611.     void *Mem = getAllocator().Allocate<IdentifierInfo>();
  612.     II = new (Mem) IdentifierInfo();
  613.  
  614.     // Make sure getName() knows how to find the IdentifierInfo
  615.     // contents.
  616.     II->Entry = &Entry;
  617.  
  618.     return *II;
  619.   }
  620.  
  621.   IdentifierInfo &get(StringRef Name, tok::TokenKind TokenCode) {
  622.     IdentifierInfo &II = get(Name);
  623.     II.TokenID = TokenCode;
  624.     assert(II.TokenID == (unsigned) TokenCode && "TokenCode too large");
  625.     return II;
  626.   }
  627.  
  628.   /// Gets an IdentifierInfo for the given name without consulting
  629.   ///        external sources.
  630.   ///
  631.   /// This is a version of get() meant for external sources that want to
  632.   /// introduce or modify an identifier. If they called get(), they would
  633.   /// likely end up in a recursion.
  634.   IdentifierInfo &getOwn(StringRef Name) {
  635.     auto &Entry = *HashTable.insert(std::make_pair(Name, nullptr)).first;
  636.  
  637.     IdentifierInfo *&II = Entry.second;
  638.     if (II)
  639.       return *II;
  640.  
  641.     // Lookups failed, make a new IdentifierInfo.
  642.     void *Mem = getAllocator().Allocate<IdentifierInfo>();
  643.     II = new (Mem) IdentifierInfo();
  644.  
  645.     // Make sure getName() knows how to find the IdentifierInfo
  646.     // contents.
  647.     II->Entry = &Entry;
  648.  
  649.     // If this is the 'import' contextual keyword, mark it as such.
  650.     if (Name.equals("import"))
  651.       II->setModulesImport(true);
  652.  
  653.     return *II;
  654.   }
  655.  
  656.   using iterator = HashTableTy::const_iterator;
  657.   using const_iterator = HashTableTy::const_iterator;
  658.  
  659.   iterator begin() const { return HashTable.begin(); }
  660.   iterator end() const   { return HashTable.end(); }
  661.   unsigned size() const  { return HashTable.size(); }
  662.  
  663.   iterator find(StringRef Name) const { return HashTable.find(Name); }
  664.  
  665.   /// Print some statistics to stderr that indicate how well the
  666.   /// hashing is doing.
  667.   void PrintStats() const;
  668.  
  669.   /// Populate the identifier table with info about the language keywords
  670.   /// for the language specified by \p LangOpts.
  671.   void AddKeywords(const LangOptions &LangOpts);
  672.  
  673.   /// Returns the correct diagnostic to issue for a future-compat diagnostic
  674.   /// warning. Note, this function assumes the identifier passed has already
  675.   /// been determined to be a future compatible keyword.
  676.   diag::kind getFutureCompatDiagKind(const IdentifierInfo &II,
  677.                                      const LangOptions &LangOpts);
  678. };
  679.  
  680. /// A family of Objective-C methods.
  681. ///
  682. /// These families have no inherent meaning in the language, but are
  683. /// nonetheless central enough in the existing implementations to
  684. /// merit direct AST support.  While, in theory, arbitrary methods can
  685. /// be considered to form families, we focus here on the methods
  686. /// involving allocation and retain-count management, as these are the
  687. /// most "core" and the most likely to be useful to diverse clients
  688. /// without extra information.
  689. ///
  690. /// Both selectors and actual method declarations may be classified
  691. /// into families.  Method families may impose additional restrictions
  692. /// beyond their selector name; for example, a method called '_init'
  693. /// that returns void is not considered to be in the 'init' family
  694. /// (but would be if it returned 'id').  It is also possible to
  695. /// explicitly change or remove a method's family.  Therefore the
  696. /// method's family should be considered the single source of truth.
  697. enum ObjCMethodFamily {
  698.   /// No particular method family.
  699.   OMF_None,
  700.  
  701.   // Selectors in these families may have arbitrary arity, may be
  702.   // written with arbitrary leading underscores, and may have
  703.   // additional CamelCase "words" in their first selector chunk
  704.   // following the family name.
  705.   OMF_alloc,
  706.   OMF_copy,
  707.   OMF_init,
  708.   OMF_mutableCopy,
  709.   OMF_new,
  710.  
  711.   // These families are singletons consisting only of the nullary
  712.   // selector with the given name.
  713.   OMF_autorelease,
  714.   OMF_dealloc,
  715.   OMF_finalize,
  716.   OMF_release,
  717.   OMF_retain,
  718.   OMF_retainCount,
  719.   OMF_self,
  720.   OMF_initialize,
  721.  
  722.   // performSelector families
  723.   OMF_performSelector
  724. };
  725.  
  726. /// Enough bits to store any enumerator in ObjCMethodFamily or
  727. /// InvalidObjCMethodFamily.
  728. enum { ObjCMethodFamilyBitWidth = 4 };
  729.  
  730. /// An invalid value of ObjCMethodFamily.
  731. enum { InvalidObjCMethodFamily = (1 << ObjCMethodFamilyBitWidth) - 1 };
  732.  
  733. /// A family of Objective-C methods.
  734. ///
  735. /// These are family of methods whose result type is initially 'id', but
  736. /// but are candidate for the result type to be changed to 'instancetype'.
  737. enum ObjCInstanceTypeFamily {
  738.   OIT_None,
  739.   OIT_Array,
  740.   OIT_Dictionary,
  741.   OIT_Singleton,
  742.   OIT_Init,
  743.   OIT_ReturnsSelf
  744. };
  745.  
  746. enum ObjCStringFormatFamily {
  747.   SFF_None,
  748.   SFF_NSString,
  749.   SFF_CFString
  750. };
  751.  
  752. /// Smart pointer class that efficiently represents Objective-C method
  753. /// names.
  754. ///
  755. /// This class will either point to an IdentifierInfo or a
  756. /// MultiKeywordSelector (which is private). This enables us to optimize
  757. /// selectors that take no arguments and selectors that take 1 argument, which
  758. /// accounts for 78% of all selectors in Cocoa.h.
  759. class Selector {
  760.   friend class Diagnostic;
  761.   friend class SelectorTable; // only the SelectorTable can create these
  762.   friend class DeclarationName; // and the AST's DeclarationName.
  763.  
  764.   enum IdentifierInfoFlag {
  765.     // Empty selector = 0. Note that these enumeration values must
  766.     // correspond to the enumeration values of DeclarationName::StoredNameKind
  767.     ZeroArg  = 0x01,
  768.     OneArg   = 0x02,
  769.     MultiArg = 0x07,
  770.     ArgFlags = 0x07
  771.   };
  772.  
  773.   /// A pointer to the MultiKeywordSelector or IdentifierInfo. We use the low
  774.   /// three bits of InfoPtr to store an IdentifierInfoFlag. Note that in any
  775.   /// case IdentifierInfo and MultiKeywordSelector are already aligned to
  776.   /// 8 bytes even on 32 bits archs because of DeclarationName.
  777.   uintptr_t InfoPtr = 0;
  778.  
  779.   Selector(IdentifierInfo *II, unsigned nArgs) {
  780.     InfoPtr = reinterpret_cast<uintptr_t>(II);
  781.     assert((InfoPtr & ArgFlags) == 0 &&"Insufficiently aligned IdentifierInfo");
  782.     assert(nArgs < 2 && "nArgs not equal to 0/1");
  783.     InfoPtr |= nArgs+1;
  784.   }
  785.  
  786.   Selector(MultiKeywordSelector *SI) {
  787.     InfoPtr = reinterpret_cast<uintptr_t>(SI);
  788.     assert((InfoPtr & ArgFlags) == 0 &&"Insufficiently aligned IdentifierInfo");
  789.     InfoPtr |= MultiArg;
  790.   }
  791.  
  792.   IdentifierInfo *getAsIdentifierInfo() const {
  793.     if (getIdentifierInfoFlag() < MultiArg)
  794.       return reinterpret_cast<IdentifierInfo *>(InfoPtr & ~ArgFlags);
  795.     return nullptr;
  796.   }
  797.  
  798.   MultiKeywordSelector *getMultiKeywordSelector() const {
  799.     return reinterpret_cast<MultiKeywordSelector *>(InfoPtr & ~ArgFlags);
  800.   }
  801.  
  802.   unsigned getIdentifierInfoFlag() const {
  803.     return InfoPtr & ArgFlags;
  804.   }
  805.  
  806.   static ObjCMethodFamily getMethodFamilyImpl(Selector sel);
  807.  
  808.   static ObjCStringFormatFamily getStringFormatFamilyImpl(Selector sel);
  809.  
  810. public:
  811.   /// The default ctor should only be used when creating data structures that
  812.   ///  will contain selectors.
  813.   Selector() = default;
  814.   explicit Selector(uintptr_t V) : InfoPtr(V) {}
  815.  
  816.   /// operator==/!= - Indicate whether the specified selectors are identical.
  817.   bool operator==(Selector RHS) const {
  818.     return InfoPtr == RHS.InfoPtr;
  819.   }
  820.   bool operator!=(Selector RHS) const {
  821.     return InfoPtr != RHS.InfoPtr;
  822.   }
  823.  
  824.   void *getAsOpaquePtr() const {
  825.     return reinterpret_cast<void*>(InfoPtr);
  826.   }
  827.  
  828.   /// Determine whether this is the empty selector.
  829.   bool isNull() const { return InfoPtr == 0; }
  830.  
  831.   // Predicates to identify the selector type.
  832.   bool isKeywordSelector() const {
  833.     return getIdentifierInfoFlag() != ZeroArg;
  834.   }
  835.  
  836.   bool isUnarySelector() const {
  837.     return getIdentifierInfoFlag() == ZeroArg;
  838.   }
  839.  
  840.   /// If this selector is the specific keyword selector described by Names.
  841.   bool isKeywordSelector(ArrayRef<StringRef> Names) const;
  842.  
  843.   /// If this selector is the specific unary selector described by Name.
  844.   bool isUnarySelector(StringRef Name) const;
  845.  
  846.   unsigned getNumArgs() const;
  847.  
  848.   /// Retrieve the identifier at a given position in the selector.
  849.   ///
  850.   /// Note that the identifier pointer returned may be NULL. Clients that only
  851.   /// care about the text of the identifier string, and not the specific,
  852.   /// uniqued identifier pointer, should use \c getNameForSlot(), which returns
  853.   /// an empty string when the identifier pointer would be NULL.
  854.   ///
  855.   /// \param argIndex The index for which we want to retrieve the identifier.
  856.   /// This index shall be less than \c getNumArgs() unless this is a keyword
  857.   /// selector, in which case 0 is the only permissible value.
  858.   ///
  859.   /// \returns the uniqued identifier for this slot, or NULL if this slot has
  860.   /// no corresponding identifier.
  861.   IdentifierInfo *getIdentifierInfoForSlot(unsigned argIndex) const;
  862.  
  863.   /// Retrieve the name at a given position in the selector.
  864.   ///
  865.   /// \param argIndex The index for which we want to retrieve the name.
  866.   /// This index shall be less than \c getNumArgs() unless this is a keyword
  867.   /// selector, in which case 0 is the only permissible value.
  868.   ///
  869.   /// \returns the name for this slot, which may be the empty string if no
  870.   /// name was supplied.
  871.   StringRef getNameForSlot(unsigned argIndex) const;
  872.  
  873.   /// Derive the full selector name (e.g. "foo:bar:") and return
  874.   /// it as an std::string.
  875.   std::string getAsString() const;
  876.  
  877.   /// Prints the full selector name (e.g. "foo:bar:").
  878.   void print(llvm::raw_ostream &OS) const;
  879.  
  880.   void dump() const;
  881.  
  882.   /// Derive the conventional family of this method.
  883.   ObjCMethodFamily getMethodFamily() const {
  884.     return getMethodFamilyImpl(*this);
  885.   }
  886.  
  887.   ObjCStringFormatFamily getStringFormatFamily() const {
  888.     return getStringFormatFamilyImpl(*this);
  889.   }
  890.  
  891.   static Selector getEmptyMarker() {
  892.     return Selector(uintptr_t(-1));
  893.   }
  894.  
  895.   static Selector getTombstoneMarker() {
  896.     return Selector(uintptr_t(-2));
  897.   }
  898.  
  899.   static ObjCInstanceTypeFamily getInstTypeMethodFamily(Selector sel);
  900. };
  901.  
  902. /// This table allows us to fully hide how we implement
  903. /// multi-keyword caching.
  904. class SelectorTable {
  905.   // Actually a SelectorTableImpl
  906.   void *Impl;
  907.  
  908. public:
  909.   SelectorTable();
  910.   SelectorTable(const SelectorTable &) = delete;
  911.   SelectorTable &operator=(const SelectorTable &) = delete;
  912.   ~SelectorTable();
  913.  
  914.   /// Can create any sort of selector.
  915.   ///
  916.   /// \p NumArgs indicates whether this is a no argument selector "foo", a
  917.   /// single argument selector "foo:" or multi-argument "foo:bar:".
  918.   Selector getSelector(unsigned NumArgs, IdentifierInfo **IIV);
  919.  
  920.   Selector getUnarySelector(IdentifierInfo *ID) {
  921.     return Selector(ID, 1);
  922.   }
  923.  
  924.   Selector getNullarySelector(IdentifierInfo *ID) {
  925.     return Selector(ID, 0);
  926.   }
  927.  
  928.   /// Return the total amount of memory allocated for managing selectors.
  929.   size_t getTotalMemory() const;
  930.  
  931.   /// Return the default setter name for the given identifier.
  932.   ///
  933.   /// This is "set" + \p Name where the initial character of \p Name
  934.   /// has been capitalized.
  935.   static SmallString<64> constructSetterName(StringRef Name);
  936.  
  937.   /// Return the default setter selector for the given identifier.
  938.   ///
  939.   /// This is "set" + \p Name where the initial character of \p Name
  940.   /// has been capitalized.
  941.   static Selector constructSetterSelector(IdentifierTable &Idents,
  942.                                           SelectorTable &SelTable,
  943.                                           const IdentifierInfo *Name);
  944.  
  945.   /// Return the property name for the given setter selector.
  946.   static std::string getPropertyNameFromSetterSelector(Selector Sel);
  947. };
  948.  
  949. namespace detail {
  950.  
  951. /// DeclarationNameExtra is used as a base of various uncommon special names.
  952. /// This class is needed since DeclarationName has not enough space to store
  953. /// the kind of every possible names. Therefore the kind of common names is
  954. /// stored directly in DeclarationName, and the kind of uncommon names is
  955. /// stored in DeclarationNameExtra. It is aligned to 8 bytes because
  956. /// DeclarationName needs the lower 3 bits to store the kind of common names.
  957. /// DeclarationNameExtra is tightly coupled to DeclarationName and any change
  958. /// here is very likely to require changes in DeclarationName(Table).
  959. class alignas(IdentifierInfoAlignment) DeclarationNameExtra {
  960.   friend class clang::DeclarationName;
  961.   friend class clang::DeclarationNameTable;
  962.  
  963. protected:
  964.   /// The kind of "extra" information stored in the DeclarationName. See
  965.   /// @c ExtraKindOrNumArgs for an explanation of how these enumerator values
  966.   /// are used. Note that DeclarationName depends on the numerical values
  967.   /// of the enumerators in this enum. See DeclarationName::StoredNameKind
  968.   /// for more info.
  969.   enum ExtraKind {
  970.     CXXDeductionGuideName,
  971.     CXXLiteralOperatorName,
  972.     CXXUsingDirective,
  973.     ObjCMultiArgSelector
  974.   };
  975.  
  976.   /// ExtraKindOrNumArgs has one of the following meaning:
  977.   ///  * The kind of an uncommon C++ special name. This DeclarationNameExtra
  978.   ///    is in this case in fact either a CXXDeductionGuideNameExtra or
  979.   ///    a CXXLiteralOperatorIdName.
  980.   ///
  981.   ///  * It may be also name common to C++ using-directives (CXXUsingDirective),
  982.   ///
  983.   ///  * Otherwise it is ObjCMultiArgSelector+NumArgs, where NumArgs is
  984.   ///    the number of arguments in the Objective-C selector, in which
  985.   ///    case the DeclarationNameExtra is also a MultiKeywordSelector.
  986.   unsigned ExtraKindOrNumArgs;
  987.  
  988.   DeclarationNameExtra(ExtraKind Kind) : ExtraKindOrNumArgs(Kind) {}
  989.   DeclarationNameExtra(unsigned NumArgs)
  990.       : ExtraKindOrNumArgs(ObjCMultiArgSelector + NumArgs) {}
  991.  
  992.   /// Return the corresponding ExtraKind.
  993.   ExtraKind getKind() const {
  994.     return static_cast<ExtraKind>(ExtraKindOrNumArgs >
  995.                                           (unsigned)ObjCMultiArgSelector
  996.                                       ? (unsigned)ObjCMultiArgSelector
  997.                                       : ExtraKindOrNumArgs);
  998.   }
  999.  
  1000.   /// Return the number of arguments in an ObjC selector. Only valid when this
  1001.   /// is indeed an ObjCMultiArgSelector.
  1002.   unsigned getNumArgs() const {
  1003.     assert(ExtraKindOrNumArgs >= (unsigned)ObjCMultiArgSelector &&
  1004.            "getNumArgs called but this is not an ObjC selector!");
  1005.     return ExtraKindOrNumArgs - (unsigned)ObjCMultiArgSelector;
  1006.   }
  1007. };
  1008.  
  1009. } // namespace detail
  1010.  
  1011. }  // namespace clang
  1012.  
  1013. namespace llvm {
  1014.  
  1015. /// Define DenseMapInfo so that Selectors can be used as keys in DenseMap and
  1016. /// DenseSets.
  1017. template <>
  1018. struct DenseMapInfo<clang::Selector> {
  1019.   static clang::Selector getEmptyKey() {
  1020.     return clang::Selector::getEmptyMarker();
  1021.   }
  1022.  
  1023.   static clang::Selector getTombstoneKey() {
  1024.     return clang::Selector::getTombstoneMarker();
  1025.   }
  1026.  
  1027.   static unsigned getHashValue(clang::Selector S);
  1028.  
  1029.   static bool isEqual(clang::Selector LHS, clang::Selector RHS) {
  1030.     return LHS == RHS;
  1031.   }
  1032. };
  1033.  
  1034. template<>
  1035. struct PointerLikeTypeTraits<clang::Selector> {
  1036.   static const void *getAsVoidPointer(clang::Selector P) {
  1037.     return P.getAsOpaquePtr();
  1038.   }
  1039.  
  1040.   static clang::Selector getFromVoidPointer(const void *P) {
  1041.     return clang::Selector(reinterpret_cast<uintptr_t>(P));
  1042.   }
  1043.  
  1044.   static constexpr int NumLowBitsAvailable = 0;
  1045. };
  1046.  
  1047. // Provide PointerLikeTypeTraits for IdentifierInfo pointers, which
  1048. // are not guaranteed to be 8-byte aligned.
  1049. template<>
  1050. struct PointerLikeTypeTraits<clang::IdentifierInfo*> {
  1051.   static void *getAsVoidPointer(clang::IdentifierInfo* P) {
  1052.     return P;
  1053.   }
  1054.  
  1055.   static clang::IdentifierInfo *getFromVoidPointer(void *P) {
  1056.     return static_cast<clang::IdentifierInfo*>(P);
  1057.   }
  1058.  
  1059.   static constexpr int NumLowBitsAvailable = 1;
  1060. };
  1061.  
  1062. template<>
  1063. struct PointerLikeTypeTraits<const clang::IdentifierInfo*> {
  1064.   static const void *getAsVoidPointer(const clang::IdentifierInfo* P) {
  1065.     return P;
  1066.   }
  1067.  
  1068.   static const clang::IdentifierInfo *getFromVoidPointer(const void *P) {
  1069.     return static_cast<const clang::IdentifierInfo*>(P);
  1070.   }
  1071.  
  1072.   static constexpr int NumLowBitsAvailable = 1;
  1073. };
  1074.  
  1075. } // namespace llvm
  1076.  
  1077. #endif // LLVM_CLANG_BASIC_IDENTIFIERTABLE_H
  1078.