source/thunkimpl.h

   1 /* This file is part of Shapes.
   2  *
   3  * Shapes is free software: you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation, either version 3 of the License, or
   6  * any later version.
   7  *
   8  * Shapes is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with Shapes.  If not, see <http://www.gnu.org/licenses/>.
  15  *
  16  * Copyright 2008 Henrik Tidefelt
  17  */
  18
  19 #include "ast.h"
  20 #include "shapesexceptions.h"
  21
  22 template< class T >
  23 Kernel::Thunk< T >::Thunk< T >( Ast::Expression * _expr, const Kernel::GraphicsState * _metaState, Kernel::PassedEnv _env )
  24         : expr( _expr ), metaState( *_metaState ), env( _env ), forced( false ), val( NullPtr< const T >( ) )
  25 { }
  26
  27 template< class T >
  28 Kernel::Thunk< T >::Thunk< T >( const RefCountPtr< const T > & _val )
  29         : forced( true ), val( _val )
  30 { }
  31
  32 template< class T >
  33 Kernel::Thunk< T >::~Thunk< T >( )
  34 { }
  35
  36 template< class T >
  37 RefCountPtr< const T >
  38 Kernel::Thunk< T >::getVal( ) const
  39 {
  40         if( ! forced )
  41                 {
  42                         RefCountPtr< const Lang::Value > untypedVal = expr->value( & metaState, env );
  43                         val = untypedVal.down_cast< const T >( );
  44                         if( val == NullPtr< const T >( ) )
  45                                 {
  46                                         throw Exceptions::TypeMismatch( expr, untypedVal->getTypeName( ), T::staticTypeName( ) );
  47                                 }
  48                         forced = true;
  49                 }
  50         return val;
  51 }