-//===-- Support/Casting.h - Allow flexible, checked, casts -------*- C++ -*--=//
+//===-- llvm/Support/Casting.h - Allow flexible, checked, casts -*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
//
// This file defines the isa<X>(), cast<X>(), dyn_cast<X>(), cast_or_null<X>(),
// and dyn_cast_or_null<X>() templates.
//
//===----------------------------------------------------------------------===//
-#ifndef SUPPORT_CASTING_H
-#define SUPPORT_CASTING_H
+#ifndef LLVM_SUPPORT_CASTING_H
+#define LLVM_SUPPORT_CASTING_H
-// real_type - Provide a macro to get the real type of a value that might be
-// a use. This provides a typedef 'Type' that is the argument type for all
-// non UseTy types, and is the contained pointer type of the use if it is a
-// UseTy.
-//
-template <class X> class real_type { typedef X Type; };
+namespace llvm {
//===----------------------------------------------------------------------===//
-// Type Checking Templates
+// isa<x> Support Templates
//===----------------------------------------------------------------------===//
+template<typename FromCl> struct isa_impl_cl;
+
+// Define a template that can be specialized by smart pointers to reflect the
+// fact that they are automatically dereferenced, and are not involved with the
+// template selection process... the default implementation is a noop.
+//
+template<typename From> struct simplify_type {
+ typedef From SimpleType; // The real type this represents...
+
+ // An accessor to get the real value...
+ static SimpleType &getSimplifiedValue(From &Val) { return Val; }
+};
+
+template<typename From> struct simplify_type<const From> {
+ typedef const From SimpleType;
+ static SimpleType &getSimplifiedValue(const From &Val) {
+ return simplify_type<From>::getSimplifiedValue(static_cast<From&>(Val));
+ }
+};
+
+
// isa<X> - Return true if the parameter to the template is an instance of the
// template type argument. Used like this:
//
-// if (isa<Type>(myVal)) { ... }
+// if (isa<Type*>(myVal)) { ... }
+//
+template <typename To, typename From>
+inline bool isa_impl(const From &Val) {
+ return To::classof(&Val);
+}
+
+template<typename To, typename From, typename SimpleType>
+struct isa_impl_wrap {
+ // When From != SimplifiedType, we can simplify the type some more by using
+ // the simplify_type template.
+ static bool doit(const From &Val) {
+ return isa_impl_cl<const SimpleType>::template
+ isa<To>(simplify_type<const From>::getSimplifiedValue(Val));
+ }
+};
+
+template<typename To, typename FromTy>
+struct isa_impl_wrap<To, const FromTy, const FromTy> {
+ // When From == SimpleType, we are as simple as we are going to get.
+ static bool doit(const FromTy &Val) {
+ return isa_impl<To,FromTy>(Val);
+ }
+};
+
+// isa_impl_cl - Use class partial specialization to transform types to a single
+// canonical form for isa_impl.
//
+template<typename FromCl>
+struct isa_impl_cl {
+ template<class ToCl>
+ static bool isa(const FromCl &Val) {
+ return isa_impl_wrap<ToCl,const FromCl,
+ typename simplify_type<const FromCl>::SimpleType>::doit(Val);
+ }
+};
+
+// Specialization used to strip const qualifiers off of the FromCl type...
+template<typename FromCl>
+struct isa_impl_cl<const FromCl> {
+ template<class ToCl>
+ static bool isa(const FromCl &Val) {
+ return isa_impl_cl<FromCl>::template isa<ToCl>(Val);
+ }
+};
+
+// Define pointer traits in terms of base traits...
+template<class FromCl>
+struct isa_impl_cl<FromCl*> {
+ template<class ToCl>
+ static bool isa(FromCl *Val) {
+ return isa_impl_cl<FromCl>::template isa<ToCl>(*Val);
+ }
+};
+
+// Define reference traits in terms of base traits...
+template<class FromCl>
+struct isa_impl_cl<FromCl&> {
+ template<class ToCl>
+ static bool isa(FromCl &Val) {
+ return isa_impl_cl<FromCl>::template isa<ToCl>(&Val);
+ }
+};
+
template <class X, class Y>
-inline bool isa(Y Val) {
- assert(Val && "isa<Ty>(NULL) invoked!");
- return X::classof(Val);
+inline bool isa(const Y &Val) {
+ return isa_impl_cl<Y>::template isa<X>(Val);
}
+//===----------------------------------------------------------------------===//
+// cast<x> Support Templates
+//===----------------------------------------------------------------------===//
+
+template<class To, class From> struct cast_retty;
+
+
+// Calculate what type the 'cast' function should return, based on a requested
+// type of To and a source type of From.
+template<class To, class From> struct cast_retty_impl {
+ typedef To& ret_type; // Normal case, return Ty&
+};
+template<class To, class From> struct cast_retty_impl<To, const From> {
+ typedef const To &ret_type; // Normal case, return Ty&
+};
+
+template<class To, class From> struct cast_retty_impl<To, From*> {
+ typedef To* ret_type; // Pointer arg case, return Ty*
+};
+
+template<class To, class From> struct cast_retty_impl<To, const From*> {
+ typedef const To* ret_type; // Constant pointer arg case, return const Ty*
+};
+
+template<class To, class From> struct cast_retty_impl<To, const From*const> {
+ typedef const To* ret_type; // Constant pointer arg case, return const Ty*
+};
+
+
+template<class To, class From, class SimpleFrom>
+struct cast_retty_wrap {
+ // When the simplified type and the from type are not the same, use the type
+ // simplifier to reduce the type, then reuse cast_retty_impl to get the
+ // resultant type.
+ typedef typename cast_retty<To, SimpleFrom>::ret_type ret_type;
+};
+
+template<class To, class FromTy>
+struct cast_retty_wrap<To, FromTy, FromTy> {
+ // When the simplified type is equal to the from type, use it directly.
+ typedef typename cast_retty_impl<To,FromTy>::ret_type ret_type;
+};
+
+template<class To, class From>
+struct cast_retty {
+ typedef typename cast_retty_wrap<To, From,
+ typename simplify_type<From>::SimpleType>::ret_type ret_type;
+};
+
+// Ensure the non-simple values are converted using the simplify_type template
+// that may be specialized by smart pointers...
+//
+template<class To, class From, class SimpleFrom> struct cast_convert_val {
+ // This is not a simple type, use the template to simplify it...
+ static typename cast_retty<To, From>::ret_type doit(const From &Val) {
+ return cast_convert_val<To, SimpleFrom,
+ typename simplify_type<SimpleFrom>::SimpleType>::doit(
+ simplify_type<From>::getSimplifiedValue(Val));
+ }
+};
+
+template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> {
+ // This _is_ a simple type, just cast it.
+ static typename cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) {
+ return reinterpret_cast<typename cast_retty<To, FromTy>::ret_type>(
+ const_cast<FromTy&>(Val));
+ }
+};
+
+
// cast<X> - Return the argument parameter cast to the specified type. This
// casting operator asserts that the type is correct, so it does not return null
// on failure. But it will correctly return NULL when the input is NULL.
// Used Like this:
//
-// cast< Instruction>(myVal)->getParent()
-// cast<const Instruction>(myVal)->getParent()
+// cast<Instruction>(myVal)->getParent()
//
template <class X, class Y>
-inline X *cast(Y Val) {
- assert(isa<X>(Val) && "cast<Ty>() argument of uncompatible type!");
- return (X*)(real_type<Y>::Type)Val;
+inline typename cast_retty<X, Y>::ret_type cast(const Y &Val) {
+ assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
+ return cast_convert_val<X, Y,
+ typename simplify_type<Y>::SimpleType>::doit(Val);
}
// cast_or_null<X> - Functionally identical to cast, except that a null value is
// accepted.
//
template <class X, class Y>
-inline X *cast_or_null(Y Val) {
- assert((Val == 0 || isa<X>(Val)) &&
- "cast_or_null<Ty>() argument of uncompatible type!");
- return (X*)(real_type<Y>::Type)Val;
+inline typename cast_retty<X, Y*>::ret_type cast_or_null(Y *Val) {
+ if (Val == 0) return 0;
+ assert(isa<X>(Val) && "cast_or_null<Ty>() argument of incompatible type!");
+ return cast<X>(Val);
}
// be used to test for a type as well as cast if successful. This should be
// used in the context of an if statement like this:
//
-// if (const Instruction *I = dyn_cast<const Instruction>(myVal)) { ... }
+// if (const Instruction *I = dyn_cast<Instruction>(myVal)) { ... }
//
template <class X, class Y>
-inline X *dyn_cast(Y Val) {
- return isa<X>(Val) ? cast<X>(Val) : 0;
+inline typename cast_retty<X, Y>::ret_type dyn_cast(Y Val) {
+ return isa<X>(Val) ? cast<X, Y>(Val) : 0;
}
// dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null
// value is accepted.
//
template <class X, class Y>
-inline X *dyn_cast_or_null(Y Val) {
- return (Val && isa<X>(Val)) ? cast<X>(Val) : 0;
+inline typename cast_retty<X, Y>::ret_type dyn_cast_or_null(Y Val) {
+ return (Val && isa<X>(Val)) ? cast<X, Y>(Val) : 0;
}
+
+#ifdef DEBUG_CAST_OPERATORS
+#include <iostream>
+
+struct bar {
+ bar() {}
+private:
+ bar(const bar &);
+};
+struct foo {
+ void ext() const;
+ /* static bool classof(const bar *X) {
+ cerr << "Classof: " << X << "\n";
+ return true;
+ }*/
+};
+
+template <> inline bool isa_impl<foo,bar>(const bar &Val) {
+ cerr << "Classof: " << &Val << "\n";
+ return true;
+}
+
+
+bar *fub();
+void test(bar &B1, const bar *B2) {
+ // test various configurations of const
+ const bar &B3 = B1;
+ const bar *const B4 = B2;
+
+ // test isa
+ if (!isa<foo>(B1)) return;
+ if (!isa<foo>(B2)) return;
+ if (!isa<foo>(B3)) return;
+ if (!isa<foo>(B4)) return;
+
+ // test cast
+ foo &F1 = cast<foo>(B1);
+ const foo *F3 = cast<foo>(B2);
+ const foo *F4 = cast<foo>(B2);
+ const foo &F8 = cast<foo>(B3);
+ const foo *F9 = cast<foo>(B4);
+ foo *F10 = cast<foo>(fub());
+
+ // test cast_or_null
+ const foo *F11 = cast_or_null<foo>(B2);
+ const foo *F12 = cast_or_null<foo>(B2);
+ const foo *F13 = cast_or_null<foo>(B4);
+ const foo *F14 = cast_or_null<foo>(fub()); // Shouldn't print.
+
+ // These lines are errors...
+ //foo *F20 = cast<foo>(B2); // Yields const foo*
+ //foo &F21 = cast<foo>(B3); // Yields const foo&
+ //foo *F22 = cast<foo>(B4); // Yields const foo*
+ //foo &F23 = cast_or_null<foo>(B1);
+ //const foo &F24 = cast_or_null<foo>(B3);
+}
+
+bar *fub() { return 0; }
+void main() {
+ bar B;
+ test(B, &B);
+}
+
+#endif
+
+} // End llvm namespace
+
#endif