Adds a modified copy of talk/base to webrtc/base. It is the first step in migrating talk/base to webrtc/base.

BUG=N/A
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12199004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6107 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/latebindingsymboltable.h

@@ -0,0 +1,69 @@
+/*
+ *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_LATEBINDINGSYMBOLTABLE_H_
+#define WEBRTC_BASE_LATEBINDINGSYMBOLTABLE_H_
+
+#include <string.h>
+
+#include "webrtc/base/common.h"
+
+namespace rtc {
+
+#if defined(WEBRTC_POSIX)
+typedef void *DllHandle;
+#else
+#error Not implemented for this platform
+#endif
+
+// This is the base class for "symbol table" classes to simplify the dynamic
+// loading of symbols from DLLs. Currently the implementation only supports
+// Linux and OS X, and pure C symbols (or extern "C" symbols that wrap C++
+// functions).  Sub-classes for specific DLLs are generated via the "supermacro"
+// files latebindingsymboltable.h.def and latebindingsymboltable.cc.def. See
+// talk/sound/pulseaudiosymboltable.(h|cc) for an example.
+class LateBindingSymbolTable {
+ public:
+  struct TableInfo {
+    const char *dll_name;
+    int num_symbols;
+    // Array of size num_symbols.
+    const char *const *symbol_names;
+  };
+
+  LateBindingSymbolTable(const TableInfo *info, void **table);
+  ~LateBindingSymbolTable();
+
+  bool IsLoaded() const;
+  // Loads the DLL and the symbol table. Returns true iff the DLL and symbol
+  // table loaded successfully.
+  bool Load();
+  // Like load, but allows overriding the dll path for when the dll path is
+  // dynamic.
+  bool LoadFromPath(const char *dll_path);
+  void Unload();
+
+  // Gets the raw OS handle to the DLL. Be careful what you do with it.
+  DllHandle GetDllHandle() const { return handle_; }
+
+ private:
+  void ClearSymbols();
+
+  const TableInfo *info_;
+  void **table_;
+  DllHandle handle_;
+  bool undefined_symbols_;
+
+  DISALLOW_COPY_AND_ASSIGN(LateBindingSymbolTable);
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_LATEBINDINGSYMBOLTABLE_H_