Dynamic Library abstraction. This makes the abstraction of a single dynamic

library (shared library/shared object) whose symbols can be looked up
dynamically. Used for plug-ins.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17940 91177308-0d34-0410-b5e6-96231b3b80d8

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diff --git a/include/llvm/System/DynamicLibrary.h b/include/llvm/System/DynamicLibrary.h
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+//===-- llvm/System/DynamicLibrary.h - Portable Dynamic Library -*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Reid Spencer and is distributed under the 
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file declares the sys::DynamicLibrary class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_DYNAMIC_LIBRARY_H
+#define LLVM_SYSTEM_DYNAMIC_LIBRARY_H
+
+#include "llvm/System/Path.h"
+#include <string>
+
+namespace llvm {
+namespace sys {
+
+  /// This class provides a portable interface to dynamic libraries which also
+  /// might be known as shared libraries, shared objects, dynamic shared 
+  /// objects, or dynamic link libraries. Regardless of the terminology or the
+  /// operating system interface, this class provides a portable interface that
+  /// allows dynamic libraries to be loaded and and searched for externally 
+  /// defined symbols. This is typically used to provide "plug-in" support.
+  /// @since 1.4
+  /// @brief Portable dynamic library abstraction.
+  class DynamicLibrary {
+    /// @name Constructors
+    /// @{
+    public:
+      /// This is the constructor for DynamicLibrary instances. It will open
+      /// the dynamic library specified by the \filename Path.
+      /// @throws std::string indicating why the library couldn't be opened.
+      /// @brief DynamicLibrary constructor
+      DynamicLibrary(const char* filename);
+
+      /// After destruction, the symbols of the library will no longer be
+      /// available to the program. It is important to make sure the lifespan
+      /// of a DynamicLibrary exceeds the lifetime of the pointers returned 
+      /// by the GetAddressOfSymbol otherwise the program may walk off into 
+      /// uncharted territory.
+      /// @see GetAddressOfSymbol.
+      /// @brief Closes the DynamicLibrary
+      ~DynamicLibrary();
+
+    /// @}
+    /// @name Accessors
+    /// @{
+    public:
+      /// Looks up a \p symbolName in the DynamicLibrary and returns its address
+      /// if it exists. If the symbol does not exist, returns (void*)0.
+      /// @returns the address of the symbol or 0.
+      /// @brief Get the address of a symbol in the DynamicLibrary.
+      void* GetAddressOfSymbol(const char* symbolName);
+
+      /// @brief Convenience function for C++ophiles.
+      void* GetAddressOfSymbol(const std::string& symbolName) {
+        return GetAddressOfSymbol(symbolName.c_str());
+      }
+
+    /// @}
+    /// @name Implementation
+    /// @{
+    protected:
+      void* handle;  // Opaque handle for information about the library
+
+      DynamicLibrary();  ///< Do not implement
+      DynamicLibrary(const DynamicLibrary&); ///< Do not implement
+      DynamicLibrary& operator=(const DynamicLibrary&); ///< Do not implement
+    /// @}
+  };
+
+} // End sys namespace
+} // End llvm namespace
+
+#endif // LLVM_SYSTEM_DYNAMIC_LIBRARY_H