forms/source/xforms/computedexpression.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  19
  20 #pragma once
  21
  22 #include <rtl/ustring.hxx>
  23 #include <com/sun/star/uno/Reference.hxx>
  24
  25 // forward declarations
  26 namespace com::sun::star
  27 {
  28     namespace xml
  29     {
  30         namespace dom { class XNode; }
  31         namespace dom { class XNodeset; }
  32         namespace xpath { class XXPathAPI; }
  33         namespace xpath { class XXPathObject; }
  34     }
  35     namespace container { class XNameContainer; }
  36 }
  37 namespace xforms { class EvaluationContext; }
  38
  39
  40 namespace xforms
  41 {
  42
  43 /** ComputedExpression represents an XPath Expression and caches results.
  44  *
  45  * As this class has no virtual methods, it should never be used
  46  * polymorphically. */
  47 class ComputedExpression
  48 {
  49     /// the expression string
  50     OUString msExpression;
  51
  52     /// is msExpression empty?
  53     bool mbIsEmpty;
  54
  55 protected:
  56     /// is msExpression a simple expression?
  57     bool mbIsSimple;
  58
  59     /// the result from the last bind
  60     css::uno::Reference<css::xml::xpath::XXPathObject> mxResult;
  61
  62
  63     /// implementation of isSimpleExpression
  64     bool _checkExpression( const char* pExpression ) const;
  65
  66     /// allow manipulation of the expression before it is evaluated
  67     // the default implementation is to do nothing...
  68     const OUString& _getExpressionForEvaluation() const { return msExpression; }
  69
  70     /// obtain a (suitable) XPathAPI implementation
  71     static css::uno::Reference<css::xml::xpath::XXPathAPI> _getXPathAPI(const xforms::EvaluationContext& aContext);
  72
  73     /// evaluate the expression relative to the content node.
  74     bool _evaluate( const xforms::EvaluationContext& rContext,
  75                     const OUString& sExpression );
  76
  77
  78 public:
  79     ComputedExpression();
  80     ~ComputedExpression();
  81
  82
  83     /// get the expression string
  84     const OUString& getExpression() const { return msExpression;}
  85
  86     /// set a new expression string
  87     void setExpression( const OUString& rExpression );
  88
  89     /// do we have an actual expression?
  90     bool isEmptyExpression() const { return mbIsEmpty;}
  91
  92     /// heuristically determine whether this expression is 'simple',
  93     /// i.e. whether its value will change depending on the values
  94     /// of other nodes
  95     bool isSimpleExpression() const;
  96
  97
  98     /// evaluate the expression relative to the content node.
  99     bool evaluate( const xforms::EvaluationContext& rContext );
 100
 101
 102     /// does this expression have a value?
 103     bool hasValue() const;
 104
 105
 106     /// remove value/evaluate results
 107     void clear();
 108
 109
 110     // get the result of this expression as string/bool/...
 111     // (Results will be based on the last call of evaluate(..). The caller
 112     // must call evaluate to ensure current results.)
 113     css::uno::Reference<css::xml::xpath::XXPathObject> const & getXPath() const { return mxResult;}
 114     bool getBool( bool bDefault = false ) const;
 115     OUString getString() const;
 116
 117 };
 118
 119 } // namespace xforms
 120
 121 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */