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      1 //===--- LambdaCapture.h - Types for C++ Lambda Captures --------*- C++ -*-===//
      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 /// \file
     11 /// \brief Defines the LambdaCapture class.
     12 ///
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_CLANG_AST_LAMBDACAPTURE_H
     16 #define LLVM_CLANG_AST_LAMBDACAPTURE_H
     17 
     18 #include "clang/AST/Decl.h"
     19 #include "clang/Basic/Lambda.h"
     20 #include "llvm/ADT/PointerIntPair.h"
     21 
     22 namespace clang {
     23 
     24 /// \brief Describes the capture of a variable or of \c this, or of a
     25 /// C++1y init-capture.
     26 class LambdaCapture {
     27   enum {
     28     /// \brief Flag used by the Capture class to indicate that the given
     29     /// capture was implicit.
     30     Capture_Implicit = 0x01,
     31 
     32     /// \brief Flag used by the Capture class to indicate that the
     33     /// given capture was by-copy.
     34     ///
     35     /// This includes the case of a non-reference init-capture.
     36     Capture_ByCopy = 0x02
     37   };
     38 
     39   llvm::PointerIntPair<Decl *, 2> DeclAndBits;
     40   SourceLocation Loc;
     41   SourceLocation EllipsisLoc;
     42 
     43   friend class ASTStmtReader;
     44   friend class ASTStmtWriter;
     45 
     46 public:
     47   /// \brief Create a new capture of a variable or of \c this.
     48   ///
     49   /// \param Loc The source location associated with this capture.
     50   ///
     51   /// \param Kind The kind of capture (this, byref, bycopy), which must
     52   /// not be init-capture.
     53   ///
     54   /// \param Implicit Whether the capture was implicit or explicit.
     55   ///
     56   /// \param Var The local variable being captured, or null if capturing
     57   /// \c this.
     58   ///
     59   /// \param EllipsisLoc The location of the ellipsis (...) for a
     60   /// capture that is a pack expansion, or an invalid source
     61   /// location to indicate that this is not a pack expansion.
     62   LambdaCapture(SourceLocation Loc, bool Implicit, LambdaCaptureKind Kind,
     63                 VarDecl *Var = nullptr,
     64                 SourceLocation EllipsisLoc = SourceLocation());
     65 
     66   /// \brief Determine the kind of capture.
     67   LambdaCaptureKind getCaptureKind() const;
     68 
     69   /// \brief Determine whether this capture handles the C++ \c this
     70   /// pointer.
     71   bool capturesThis() const {
     72     return (DeclAndBits.getPointer() == nullptr) &&
     73            !(DeclAndBits.getInt() & Capture_ByCopy);
     74   }
     75 
     76   /// \brief Determine whether this capture handles a variable.
     77   bool capturesVariable() const {
     78     return dyn_cast_or_null<VarDecl>(DeclAndBits.getPointer());
     79   }
     80 
     81   /// \brief Determine whether this captures a variable length array bound
     82   /// expression.
     83   bool capturesVLAType() const {
     84     return (DeclAndBits.getPointer() == nullptr) &&
     85            (DeclAndBits.getInt() & Capture_ByCopy);
     86   }
     87 
     88   /// \brief Determine whether this is an init-capture.
     89   bool isInitCapture() const {
     90     return capturesVariable() && getCapturedVar()->isInitCapture();
     91   }
     92 
     93   /// \brief Retrieve the declaration of the local variable being
     94   /// captured.
     95   ///
     96   /// This operation is only valid if this capture is a variable capture
     97   /// (other than a capture of \c this).
     98   VarDecl *getCapturedVar() const {
     99     assert(capturesVariable() && "No variable available for 'this' capture");
    100     return cast<VarDecl>(DeclAndBits.getPointer());
    101   }
    102 
    103   /// \brief Determine whether this was an implicit capture (not
    104   /// written between the square brackets introducing the lambda).
    105   bool isImplicit() const { return DeclAndBits.getInt() & Capture_Implicit; }
    106 
    107   /// \brief Determine whether this was an explicit capture (written
    108   /// between the square brackets introducing the lambda).
    109   bool isExplicit() const { return !isImplicit(); }
    110 
    111   /// \brief Retrieve the source location of the capture.
    112   ///
    113   /// For an explicit capture, this returns the location of the
    114   /// explicit capture in the source. For an implicit capture, this
    115   /// returns the location at which the variable or \c this was first
    116   /// used.
    117   SourceLocation getLocation() const { return Loc; }
    118 
    119   /// \brief Determine whether this capture is a pack expansion,
    120   /// which captures a function parameter pack.
    121   bool isPackExpansion() const { return EllipsisLoc.isValid(); }
    122 
    123   /// \brief Retrieve the location of the ellipsis for a capture
    124   /// that is a pack expansion.
    125   SourceLocation getEllipsisLoc() const {
    126     assert(isPackExpansion() && "No ellipsis location for a non-expansion");
    127     return EllipsisLoc;
    128   }
    129 };
    130 
    131 } // end namespace clang
    132 
    133 #endif // LLVM_CLANG_AST_LAMBDACAPTURE_H
    134