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2cdf0e10cSrcweir  *
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21*aaef562fSAndrew Rist 
22*aaef562fSAndrew Rist 
23cdf0e10cSrcweir 
24cdf0e10cSrcweir #ifndef INCLUDED_SLIDESHOW_EXPRESSIONNODE_HXX
25cdf0e10cSrcweir #define INCLUDED_SLIDESHOW_EXPRESSIONNODE_HXX
26cdf0e10cSrcweir 
27cdf0e10cSrcweir #include "animationfunction.hxx"
28cdf0e10cSrcweir 
29cdf0e10cSrcweir 
30cdf0e10cSrcweir /* Definition of ExpressionNode interface */
31cdf0e10cSrcweir 
32cdf0e10cSrcweir namespace slideshow
33cdf0e10cSrcweir {
34cdf0e10cSrcweir     namespace internal
35cdf0e10cSrcweir     {
36cdf0e10cSrcweir         /** Refinement of AnimationFunction
37cdf0e10cSrcweir 
38cdf0e10cSrcweir 	        This interface is used by the SMIL function parser, to
39cdf0e10cSrcweir 	        collapse constant values into precalculated, single nodes.
40cdf0e10cSrcweir         */
41cdf0e10cSrcweir         class ExpressionNode : public AnimationFunction
42cdf0e10cSrcweir         {
43cdf0e10cSrcweir         public:
44cdf0e10cSrcweir             /** Predicate whether this node is constant.
45cdf0e10cSrcweir 
46cdf0e10cSrcweir         	    This predicate returns true, if this node is
47cdf0e10cSrcweir                 neither time- nor ViewInfo dependent. This allows
48cdf0e10cSrcweir                 for certain obtimizations, i.e. not the full
49cdf0e10cSrcweir                 expression tree needs be represented by
50cdf0e10cSrcweir                 ExpressionNodes.
51cdf0e10cSrcweir 
52cdf0e10cSrcweir                 @returns true, if this node is neither time- nor
53cdf0e10cSrcweir                 ViewInfo dependent
54cdf0e10cSrcweir             */
55cdf0e10cSrcweir             virtual bool isConstant() const = 0;
56cdf0e10cSrcweir         };
57cdf0e10cSrcweir 
58cdf0e10cSrcweir         typedef ::boost::shared_ptr< ExpressionNode > ExpressionNodeSharedPtr;
59cdf0e10cSrcweir     }
60cdf0e10cSrcweir }
61cdf0e10cSrcweir 
62cdf0e10cSrcweir #endif /* INCLUDED_SLIDESHOW_EXPRESSIONNODE_HXX */
63