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import com.icl.saxon.Context;
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import com.icl.saxon.expr.Expression;
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import com.icl.saxon.style.StyleElement;
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public class CheckAvailabilityElement extends StyleElement
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{
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//some other methods//
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public void process(final Context aContext) throws BusinessException
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{
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boolean result = true;
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final String availabilityString =
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evaluateExpressionAsString(this.availability, aContext, false);
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// some additional logic
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}
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protected String evaluateExpressionAsString(
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final Expression anExpression, final Context aContext, final boolean isRequired)
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throws BusinessException
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{
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//---------------------------------------------------------------------------
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// The expression may be null if and only if optional flag has been specified
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//---------------------------------------------------------------------------
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if (anExpression == null)
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{
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if (isRequired)
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{
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final String message = "Null expression is not allowed";
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//If the expression is null, then throw error
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final BusinessException exception = styleError(message);
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throw exception;
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}
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else
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{
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return null;
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}
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}
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//------------------------
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// Evaluate the expression
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//------------------------
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final String result;
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try
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{
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result = anExpression.evaluateAsString(aContext);
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}
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catch (final XPathException anException)
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{
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final String message = "Error evaluating expression";
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throw new BusinessException(message, this, anException);
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}
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//--------------------------------
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// Check for empty or null results
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//--------------------------------
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if ((result == null) || (result.length()) == 0)
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{
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if (isRequired)
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{
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final String message =
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"Required expression evaluated to an empty value: " + anExpression.toString();
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final BusinessException exception = styleError(message);
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throw exception;
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}
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else
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{
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return null;
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}
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}
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return result;
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}
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//some other methods//
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}
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