libcore/builtin_function.h

   1 //
   2 //   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
   3 //   Free Software Foundation, Inc
   4 //
   5 // This program is free software; you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation; either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // This program is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with this program; if not, write to the Free Software
  17 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18
  19 #ifndef GNASH_BUILTIN_FUNCTION_H
  20 #define GNASH_BUILTIN_FUNCTION_H
  21
  22 #include "UserFunction.h"
  23
  24 #include <cassert>
  25
  26 namespace gnash {
  27     class fn_call;
  28 }
  29
  30 namespace gnash {
  31
  32
  33 /// This is a special type of function implementing AS-code in C++
  34 //
  35 /// Many functions (including classes) are implemented in ActionScript in
  36 /// the reference player. Gnash implements them in C++, but they must
  37 /// be treated like swf-defined functions.
  38 //
  39 /// They are distinct from NativeFunctions, which are part of the player and
  40 /// do not go through the ActionScript interpreter.
  41 class builtin_function : public UserFunction
  42 {
  43     typedef as_value (*ASFunction)(const fn_call& fn);
  44
  45 public:
  46
  47         /// Construct a builtin function/class with a default interface
  48         //
  49         /// The default interface will have a constructor member set as 'this'
  50         ///
  51         /// @param func
  52         ///     The C function to call when this as_function is invoked.
  53         ///     For classes, the function pointer is the constructor.
  54         builtin_function(Global_as& gl, ASFunction func)
  55                 :
  56                 UserFunction(gl),
  57                 _func(func)
  58         {
  59         }
  60
  61     /// Return the number of registers required for function execution
  62     //
  63     /// Gnash's C++ implementations of AS functions don't need any registers!
  64     virtual std::uint8_t registers() const {
  65         return 0;
  66     }
  67
  68         /// Invoke this function or this Class constructor
  69         virtual as_value call(const fn_call& fn)
  70         {
  71                 FrameGuard guard(getVM(fn), *this);
  72
  73                 assert(_func);
  74                 return _func(fn);
  75         }
  76
  77         bool isBuiltin()  { return true; }
  78
  79 private:
  80
  81         ASFunction _func;
  82 };
  83
  84 } // end of gnash namespace
  85
  86 #endif
  87