forms/source/xforms/computedexpression.hxx

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  30
  31 #ifndef _COMPUTEDEXPRESSION_HXX
  32 #define _COMPUTEDEXPRESSION_HXX
  33
  34
  35 // includes for member variables
  36 #include <rtl/ustring.hxx>
  37 #include <com/sun/star/uno/Reference.hxx>
  38
  39 // forward declaractions
  40 namespace com { namespace sun { namespace star
  41 {
  42     namespace xml
  43     {
  44         namespace dom { class XNode; }
  45         namespace dom { class XNodeset; }
  46         namespace xpath { class XXPathAPI; }
  47         namespace xpath { class XXPathObject; }
  48     }
  49     namespace container { class XNameContainer; }
  50 } } }
  51 namespace xforms { class EvaluationContext; }
  52
  53
  54
  55 namespace xforms
  56 {
  57
  58 /** ComputedExpression represents an XPath Expression and caches results.
  59  *
  60  * As this class has no virtual methods, it should never be used
  61  * polymorphically. */
  62 class ComputedExpression
  63 {
  64     /// the expression string
  65     rtl::OUString msExpression;
  66
  67     /// is msExpression empty?
  68     bool mbIsEmpty;
  69
  70 protected:
  71     /// is msExpression a simple expression?
  72     bool mbIsSimple;
  73
  74     /// the result from the last bind
  75     com::sun::star::uno::Reference<com::sun::star::xml::xpath::XXPathObject> mxResult;
  76
  77
  78     /// implementation of isSimpleExpression
  79     bool _checkExpression( const sal_Char* pExpression ) const;
  80
  81     /// allow manipulation of the expression before it is evaluated
  82     const rtl::OUString _getExpressionForEvaluation() const;
  83
  84     /// obtain a (suitable) XPathAPI implementation
  85     com::sun::star::uno::Reference<com::sun::star::xml::xpath::XXPathAPI> _getXPathAPI(const xforms::EvaluationContext& aContext);
  86
  87     /// evaluate the expression relative to the content node.
  88     bool _evaluate( const xforms::EvaluationContext& rContext,
  89                     const rtl::OUString& sExpression );
  90
  91
  92 public:
  93     ComputedExpression();
  94     ~ComputedExpression();
  95
  96
  97     /// get the expression string
  98     rtl::OUString getExpression() const;
  99
 100     /// set a new expression string
 101     void setExpression( const rtl::OUString& rExpression );
 102
 103     /// get the namespaces that are used to interpret the expression string
 104     com::sun::star::uno::Reference<com::sun::star::container::XNameContainer> getNamespaces() const;
 105
 106     /// set the namespaces that are used to interpret the expression string
 107     void setNamespaces( const com::sun::star::uno::Reference<com::sun::star::container::XNameContainer>& );
 108
 109     /// do we have an actual expression?
 110     bool isEmptyExpression() const;
 111
 112     /// heuristically determine whether this expression is 'simple',
 113     /// i.e. whether its value will change depending on the values
 114     /// of other nodes
 115     bool isSimpleExpression() const;
 116
 117
 118     /// evaluate the expression relative to the content node.
 119     bool evaluate( const xforms::EvaluationContext& rContext );
 120
 121
 122     /// does this expression have a value?
 123     bool hasValue() const;
 124
 125
 126     /// remove value/evaluate results
 127     void clear();
 128
 129
 130     // get the result of this expression as string/bool/...
 131     // (Results will be based on the last call of evaluate(..). The caller
 132     // must call evaluate to ensure current results.)
 133     com::sun::star::uno::Reference<com::sun::star::xml::xpath::XXPathObject> getXPath();
 134     bool getBool( bool bDefault = false ) const;
 135     rtl::OUString getString( const rtl::OUString& rDefault = rtl::OUString() ) const;
 136
 137 };
 138
 139 } // namespace xforms
 140
 141 #endif