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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2166 91177308-0d34-0410-b5e6-96231b3b80d8
81 lines
2.6 KiB
C++
81 lines
2.6 KiB
C++
//===-- Support/Casting.h - Allow flexible, checked, casts -------*- C++ -*--=//
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//
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// This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(),
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// and dyn_cast_or_null<X>() templates.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SUPPORT_CASTING_H
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#define SUPPORT_CASTING_H
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// real_type - Provide a macro to get the real type of a value that might be
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// a use. This provides a typedef 'Type' that is the argument type for all
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// non UseTy types, and is the contained pointer type of the use if it is a
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// UseTy.
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//
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template <class X> class real_type { typedef X Type; };
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//===----------------------------------------------------------------------===//
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// Type Checking Templates
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//===----------------------------------------------------------------------===//
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// isa<X> - Return true if the parameter to the template is an instance of the
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// template type argument. Used like this:
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//
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// if (isa<Type>(myVal)) { ... }
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//
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template <class X, class Y>
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inline bool isa(Y Val) {
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assert(Val && "isa<Ty>(NULL) invoked!");
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return X::classof(Val);
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}
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// cast<X> - Return the argument parameter cast to the specified type. This
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// casting operator asserts that the type is correct, so it does not return null
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// on failure. But it will correctly return NULL when the input is NULL.
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// Used Like this:
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//
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// cast< Instruction>(myVal)->getParent()
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// cast<const Instruction>(myVal)->getParent()
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//
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template <class X, class Y>
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inline X *cast(Y Val) {
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assert(isa<X>(Val) && "cast<Ty>() argument of uncompatible type!");
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return (X*)(real_type<Y>::Type)Val;
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}
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// cast_or_null<X> - Functionally identical to cast, except that a null value is
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// accepted.
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//
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template <class X, class Y>
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inline X *cast_or_null(Y Val) {
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assert((Val == 0 || isa<X>(Val)) &&
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"cast_or_null<Ty>() argument of uncompatible type!");
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return (X*)(real_type<Y>::Type)Val;
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}
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// dyn_cast<X> - Return the argument parameter cast to the specified type. This
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// casting operator returns null if the argument is of the wrong type, so it can
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// be used to test for a type as well as cast if successful. This should be
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// used in the context of an if statement like this:
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//
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// if (const Instruction *I = dyn_cast<const Instruction>(myVal)) { ... }
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//
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template <class X, class Y>
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inline X *dyn_cast(Y Val) {
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return isa<X>(Val) ? cast<X>(Val) : 0;
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}
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// dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null
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// value is accepted.
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//
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template <class X, class Y>
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inline X *dyn_cast_or_null(Y Val) {
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return (Val && isa<X>(Val)) ? cast<X>(Val) : 0;
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}
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#endif
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