1 files changed, 233 insertions, 23 deletions

diff --git a/include/llvm/Support/Casting.h b/include/llvm/Support/Casting.h
index e59b7c2..2c072d1 100644
--- a/include/llvm/Support/Casting.h
+++ b/include/llvm/Support/Casting.h
@@ -8,51 +8,196 @@
 #ifndef SUPPORT_CASTING_H
 #define 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; };
+#include <assert.h>
 
 //===----------------------------------------------------------------------===//
-//                          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((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
+// cannonical 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,
+                         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, 
+                         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 cast_retty<To, From>::ret_type doit(const From &Val) {
+    return cast_convert_val<To, SimpleFrom,
+      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 cast_retty<To, FromTy>::ret_type doit(const FromTy &Val) {
+    return (cast_retty<To, FromTy>::ret_type)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) {
+inline cast_retty<X, Y>::ret_type cast(const Y &Val) {
   assert(isa<X>(Val) && "cast<Ty>() argument of uncompatible type!");
-  return (X*)(real_type<Y>::Type)Val;
+  return cast_convert_val<X, Y, 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 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 uncompatible type!");
+  return cast<X>(Val);
 }
 
 
@@ -65,16 +210,81 @@ inline X *cast_or_null(Y Val) {
 //
 
 template <class X, class Y>
-inline X *dyn_cast(Y Val) {
-  return isa<X>(Val) ? cast<X>(Val) : 0;
+inline 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 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
+
+#endif