First round of dead file removal

experimental/c_salt/callback.h

-// Copyright 2010 The Ginsu Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can
-// be found in the LICENSE file.
-
-#ifndef C_SALT_CALLBACK_H_
-#define C_SALT_CALLBACK_H_
-
-#include "boost/function.hpp"
-#include "boost/bind.hpp"
-#include "boost/shared_ptr.hpp"
-#include "boost/type_traits/remove_const.hpp"
-#include "boost/type_traits/remove_reference.hpp"
-#include "c_salt/variant_ptrs.h"
-#include "c_salt/variant.h"
-
-namespace c_salt {
-namespace c_salt_private {
-// VariantToArgConverter is a small helper class for converting c_salt Variants
-// in to a given type, to allow them to be used as parameters.
-// For most types, just call Variant::GetValue<> function and let it do the
-// work.
-// TODO(dmichael):  Is there a nicer way to support passing c_salt::Variant as
-// a parameter?  Or is this a good way...  it is certainly extensible.  It also
-// allows us to pass the Variant through without copying.
-template <class T>
-struct VariantToArgConverter {
-  static T Get(const c_salt::SharedVariant& var) {
-    return var->GetValue<T>();
-  }
-};
-// If the argument is a c_salt::SharedVariant, just pass it through.
-template <>
-struct VariantToArgConverter<c_salt::SharedVariant> {
-  static const c_salt::SharedVariant& Get(const c_salt::SharedVariant& var) {
-    return var;
-  }
-};
-// If the argument is a c_salt::Variant, just dereference the shared_ptr.
-template <>
-struct VariantToArgConverter<c_salt::Variant> {
-  static const c_salt::Variant& Get(const c_salt::SharedVariant& var) {
-    return *var;
-  }
-};
-}  // namespace c_salt_private
-
-// Pure virtual class that provides the interface for invoking a method given
-// c_salt::Variant arguments.  Clients should generally not use this interface
-// directly; it simply allows c_salt code to invoke methods generically.  See
-// MethodCallbackExecutorImpl (and related classes) below for further
-// details on how this is achieved.
-class MethodCallbackExecutor {
- public:
-  virtual ~MethodCallbackExecutor() {}
-
-  virtual bool Execute(const SharedVariant* params_begin,
-                       const SharedVariant* params_end,
-                       SharedVariant* return_value_var) = 0;
-};
-typedef boost::shared_ptr<MethodCallbackExecutor> SharedMethodCallbackExecutor;
-
-// Templates used to support method call-backs when a method or property is
-// accessed from the browser code.
-
-// FunctionInvoker is a class template which holds a boost::function and
-// provides a means for invoking that boost::function by providing a sequence
-// of c_salt::Variant parameters.  Its purpose is to allow turning scripting
-// invocations in to a more natural C++ form.  For example, it can be used to
-// convert an NPAPI method invocation in to a conventional C++ function call,
-// or similarly for PPAPI, SRPC, etc, by mapping the parameters to a sequence of
-// c_salt::Variants.
-//
-// This is the default implementation of FunctionInvoker.  Its methods are not
-// implemented; it is left here for documentation purposes only.  Any real usage
-// of FunctionInvoker must match one of the specializations defined later.  If
-// a match is not found, it is likely because the user is attempting to create
-// a function invoker with more arguments than we currently support.
-template <class Signature>
-class FunctionInvoker {
-  // Constructor for member functions that binds the target object to the
-  // FunctionInvoker's stored boost::function.
-  template <class T>
-  FunctionInvoker(T* target_object, Signature method);
-
-  // Convert the given parameters (taken as a sequence of c_salt::Variants) in
-  // to the C++ types required by the bound function.  Then, invoke the
-  // boost::function owned by this FunctionInvoker, passing the arguments.
-  // Convert the return value to a c_salt::Variant.
-  // params_begin and params_end are pointers treated as forward iterators for a
-  // sequence that contains the arguments to be sent to the function.  Note that
-  // we could just pass a vector, but this keeps STL dependencies to more of a
-  // minimum in the interface between client-compiled code (i.e., the template)
-  // and the Google-provided library (c_salt).
-  // return_val is an out-parameter.  The caller must provide a valid pointer
-  // to a c_salt::Variant.
-  bool Invoke(const SharedVariant* begin,
-              const SharedVariant* end,
-              SharedVariant* return_value);
-};
-
-// Define some macros temporarily so that we can generate code succinctly for
-// our FunctionInvoker classes.  We need one specialization of FunctionInvoker
-// for each number of arguments, and they are largely the same.  The macros
-// abstract out the repetive parts and allow us to only duplicate the parts that
-// are unique.
-//
-// Here is an example of what the code looks like after the preprocessor is
-// finished with it, in this case for 2 arguments:
-#if 0
-template <class T, class RetType, class Arg1, class Arg2>
-class FunctionInvoker<RetType(T::*)(Arg1, Arg2)> {
- public:
-  typedef RetType ReturnType;
-  typedef ReturnType (T::*MemFunSignature) (Arg1, Arg2);
-  typedef ReturnType (*Signature) (Arg1, Arg2);
-  typedef boost::function<ReturnType (Arg1, Arg2)> FunctionType;
-
-  FunctionInvoker(T* target_object, MemFunSignature method)
-      : function_(boost::bind(method, target_object, _1, _2)) {}
-  bool Invoke(const SharedVariant* params_begin,
-              const SharedVariant* params_end,
-              SharedVariant* return_value_var) {
-    // Declare a local instance of the argument type.  If it's a const-ref
-    // parameter, remove the const-ref part of the type so we can make a local
-    // argument on the stack to pass.
-    typedef typename boost::remove_reference<Arg1>::type NoRef1;
-    typedef typename boost::remove_const<NoRef1>::type NoConstRef1;
-    NoConstRef1 arg1;
-    // See if we've run out of arguments.  If so, that's an error, so return
-    // false.
-    if (params_begin == params_end) return false;
-    // Get the value from the c_salt::Variant, which handles conversions for us.
-    NoConstRef1 arg1(::c_salt::c_salt_private::
-        VariantToArgConverter<NoConstRef1>::Get(*params_begin));
-    // Advance to the next parameter.
-    ++params_begin;
-    typedef typename boost::remove_reference<Arg2>::type NoRef2;
-    typedef typename boost::remove_const<NoRef2>::type NoConstRef2;
-    if (params_begin == params_end) return false;
-    NoConstRef2 arg2(::c_salt::c_salt_private::
-        VariantToArgConverter<NoConstRef2>::Get(*params_begin));
-    ++params_begin;
-    NoConstRef2 arg2;
-
-    // Call the function and capture the return value (note, this does not
-    // currently support void returns).
-    ReturnType retval = function_(arg1, arg2);
-    // Create a Variant using the appropriate constructor.
-    *return_value_var = SharedVariant(retval);
-    return true;
-  }
- private:
-  FunctionType function_;
-};
-#endif
-// A macro that fills in the beginning of the class definition, including
-// typedefs that we (or our clients) might find useful.
-#define FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN(ARGLIST) \
-class FunctionInvoker<RetType(T::*) ARGLIST> {\
-public:\
-  typedef RetType ReturnType;\
-  typedef ReturnType (T::*MemFunSignature) ARGLIST;\
-  typedef ReturnType (*Signature) ARGLIST;\
-  typedef boost::function<ReturnType ARGLIST> FunctionType;\
-
-// A macro for the constructor.  BIND_ARGLIST is of the form:
-// (method, target_object ...)
-// where the ... is a list of 0 or more bind placeholders (, _1, _2, etc).
-#define FUNCTIONINVOKER_CONSTRUCTOR(BIND_ARGLIST) \
-  FunctionInvoker(T* target_object, MemFunSignature method) : \
-  function_(boost::bind BIND_ARGLIST ) {}
-// end FUNCTIONINVOKER_CONSTRUCTOR
-
-// A macro for the beginning of the Invoke function.
-#define FUNCTIONINVOKER_INVOKE_BEGIN() \
-  bool Invoke(const ::c_salt::SharedVariant* params_begin, \
-              const ::c_salt::SharedVariant* params_end, \
-              ::c_salt::SharedVariant* return_value_var) {
-// end FUNCTIONINVOKER_INVOKE_BEGIN
-
-// A portion of the invoker function that converts 1 argument, returning
-// false if that conversion fails.  NUM is a positive integer.
-#define FUNCTIONINVOKER_INVOKE_CONVERT_ARG(NUM) \
-    typedef typename boost::remove_reference<Arg ## NUM>::type NoRef ## NUM; \
-    typedef typename boost::remove_const<NoRef ## NUM>::type NoConstRef ## NUM;\
-    if (params_begin == params_end) return false; \
-    NoConstRef##NUM arg##NUM(::c_salt::c_salt_private:: \
-        VariantToArgConverter<NoConstRef##NUM>::Get(*params_begin)); \
-    ++params_begin;
-// end FUNCTIONINVOKER_INVOKE_CONVERT_ARG
-
-// A macro for the end of the Invoke function.
-#define FUNCTIONINVOKER_INVOKE_END(ARGLIST) \
-    ReturnType retval = function_ ARGLIST; \
-    return_value_var->reset(new ::c_salt::Variant(retval)); \
-    return true;\
-  }
-// end FUNCTIONINVOKER_INVOKE_END
-
-// A macro for the end of the FunctionInvoker class.
-#define FUNCTIONINVOKER_CLASS_DEFINITION_END() \
-private: \
-  FunctionType function_;\
-};
-// end FUNCTIONINVOKER_CLASS_DEFINITION_END
-
-// Now we use the above macros to define FunctionInvoker partial specializations
-// for each number of arguments which we want to support.
-// 0 Args.  Note the lack of semicolons.  These macros are not written to allow
-// for semicolons.
-template <class T, class RetType>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN(())
-// Note that the parameter list here (and in INVOKE_END) must have additional
-// parens around it.  This makes it appear as 1 argument to the preprocessor,
-// and places the entire parameter list in the resultant code.
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_END(())
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-// 1 Args.
-template <class T, class RetType, class Arg1>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN((Arg1))
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object, _1))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(1)
-FUNCTIONINVOKER_INVOKE_END((arg1))
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-// 2 Args.
-template <class T, class RetType, class Arg1, class Arg2>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN((Arg1, Arg2))
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object, _1, _2))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(1)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(2)
-FUNCTIONINVOKER_INVOKE_END((arg1, arg2))
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-// 3 Args.
-template <class T, class RetType, class Arg1, class Arg2, class Arg3>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN((Arg1, Arg2, Arg3))
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object, _1, _2, _3))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(1)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(2)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(3)
-FUNCTIONINVOKER_INVOKE_END((arg1, arg2, arg3))
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-// 4 Args.
-template <class T, class RetType, class Arg1, class Arg2, class Arg3
-         , class Arg4>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN((Arg1, Arg2, Arg3, Arg4))
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object, _1, _2, _3, _4))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(1)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(2)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(3)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(4)
-FUNCTIONINVOKER_INVOKE_END((arg1, arg2, arg3, arg4))
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-// 5 Args.
-template <class T, class RetType, class Arg1, class Arg2, class Arg3
-          , class Arg4, class Arg5>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN((Arg1, Arg2, Arg3, Arg4, Arg5))
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object, _1, _2, _3, _4, _5))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(1)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(2)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(3)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(4)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(5)
-FUNCTIONINVOKER_INVOKE_END((arg1, arg2, arg3, arg4, arg5))
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-// 6 Args.
-template <class T, class RetType, class Arg1, class Arg2, class Arg3
-          , class Arg4, class Arg5, class Arg6>
-FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN((Arg1, Arg2, Arg3, Arg4, Arg5, Arg6))
-FUNCTIONINVOKER_CONSTRUCTOR((method, target_object, _1, _2, _3, _4, _5, _6))
-FUNCTIONINVOKER_INVOKE_BEGIN()
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(1)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(2)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(3)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(4)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(5)
-FUNCTIONINVOKER_INVOKE_CONVERT_ARG(6)
-FUNCTIONINVOKER_INVOKE_END((arg1, arg2, arg3, arg4, arg5, arg6))
-FUNCTIONINVOKER_CLASS_DEFINITION_END()
-
-// Now clean up so these macros aren't exported outside this .h file.
-#undef FUNCTIONINVOKER_CLASS_DEFINITION_BEGIN
-#undef FUNCTIONINVOKER_CONSTRUCTOR
-#undef FUNCTIONINVOKER_INVOKE_BEGIN
-#undef FUNCTIONINVOKER_INVOKE_CONVERT_ARG
-#undef FUNCTIONINVOKER_INVOKE_END
-#undef FUNCTIONINVOKER_CLASS_DEFINITION_END
-
-// MethodCallbackExecutorImpl is a class template that implements the
-// MethodCallbackExecutor interface by calling an arbitrary boost::function
-// and automatically handling marshalling/unmarshalling of the arguments and
-// return type to bridge the gap between the method invocation and the
-// invocation of a real C++ method on a client-defined class.
-template <class Signature>
-class MethodCallbackExecutorImpl : public MethodCallbackExecutor {
- public:
-  typedef typename ::c_salt::FunctionInvoker<Signature> FunctionInvokerType;
-
-  template <class T>
-  MethodCallbackExecutorImpl(T* instance, Signature method)
-      : function_invoker_(instance, method) {}
-  virtual ~MethodCallbackExecutorImpl() {}
-
-  virtual bool Execute(const SharedVariant* params_begin,
-                       const SharedVariant* params_end,
-                       SharedVariant* return_value_var) {
-    return function_invoker_.Invoke(params_begin,
-                                    params_end,
-                                    return_value_var);
-  }
- private:
-  FunctionInvokerType function_invoker_;
-};
-
-}  // namespace c_salt
-
-#endif  // C_SALT_CALLBACK_H_