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SingleItemFilter
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SUMMARY: NESTED | <A HREF="#fields_inherited_from_class_net.sf.saxon.expr.UnaryExpression">FIELD</A> | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD>
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<FONT SIZE="-1">
net.sf.saxon.expr</FONT>
<BR>
Class SingleItemFilter</H2>
<PRE>
<A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">java.lang.Object</A>
<IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">net.sf.saxon.expr.Expression</A>
<IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">net.sf.saxon.expr.UnaryExpression</A>
<IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><B>net.sf.saxon.expr.SingleItemFilter</B>
</PRE>
<DL>
<DT><B>All Implemented Interfaces:</B> <DD><A HREF="http://download.oracle.com/javase/6/docs/api/java/io/Serializable.html?is-external=true" title="class or interface in java.io">Serializable</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/javax/xml/transform/SourceLocator.html?is-external=true" title="class or interface in javax.xml.transform">SourceLocator</A>, <A HREF="../../../../net/sf/saxon/event/LocationProvider.html" title="interface in net.sf.saxon.event">LocationProvider</A>, <A HREF="../../../../net/sf/saxon/event/SaxonLocator.html" title="interface in net.sf.saxon.event">SaxonLocator</A>, <A HREF="../../../../net/sf/saxon/trace/InstructionInfo.html" title="interface in net.sf.saxon.trace">InstructionInfo</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/org/xml/sax/Locator.html?is-external=true" title="class or interface in org.xml.sax">Locator</A></DD>
</DL>
<DL>
<DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../../../net/sf/saxon/expr/FirstItemExpression.html" title="class in net.sf.saxon.expr">FirstItemExpression</A>, <A HREF="../../../../net/sf/saxon/expr/LastItemExpression.html" title="class in net.sf.saxon.expr">LastItemExpression</A></DD>
</DL>
<HR>
<DL>
<DT><PRE>public abstract class <B>SingleItemFilter</B><DT>extends <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">UnaryExpression</A></DL>
</PRE>
<P>
A SingleItemFilter is an expression that selects zero or one items from a supplied sequence
<P>
<P>
<DL>
<DT><B>See Also:</B><DD><A HREF="../../../../serialized-form.html#net.sf.saxon.expr.SingleItemFilter">Serialized Form</A></DL>
<HR>
<P>
<!-- =========== FIELD SUMMARY =========== -->
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<A NAME="fields_inherited_from_class_net.sf.saxon.expr.UnaryExpression"><!-- --></A>
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<TH ALIGN="left"><B>Fields inherited from class net.sf.saxon.expr.<A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">UnaryExpression</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#operand">operand</A></CODE></TD>
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<A NAME="fields_inherited_from_class_net.sf.saxon.expr.Expression"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
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<TH ALIGN="left"><B>Fields inherited from class net.sf.saxon.expr.<A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../net/sf/saxon/expr/Expression.html#EFFECTIVE_BOOLEAN_VALUE">EFFECTIVE_BOOLEAN_VALUE</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#EVALUATE_METHOD">EVALUATE_METHOD</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#EVENT_FEED_METHOD">EVENT_FEED_METHOD</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#ITEM_FEED_METHOD">ITEM_FEED_METHOD</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#ITERATE_METHOD">ITERATE_METHOD</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#locationId">locationId</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#MAX_SEQUENCE_LENGTH">MAX_SEQUENCE_LENGTH</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#MAX_STRING_LENGTH">MAX_STRING_LENGTH</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#PROCESS_METHOD">PROCESS_METHOD</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#PUSH_SELECTION">PUSH_SELECTION</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#staticProperties">staticProperties</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#UNBOUNDED_LOWER">UNBOUNDED_LOWER</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#UNBOUNDED_UPPER">UNBOUNDED_UPPER</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#WATCH_METHOD">WATCH_METHOD</A></CODE></TD>
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<!-- ======== CONSTRUCTOR SUMMARY ======== -->
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<TD><CODE><B><A HREF="../../../../net/sf/saxon/expr/SingleItemFilter.html#SingleItemFilter()">SingleItemFilter</A></B>()</CODE>
<BR>
</TD>
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<!-- ========== METHOD SUMMARY =========== -->
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<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../net/sf/saxon/expr/SingleItemFilter.html#computeCardinality()">computeCardinality</A></B>()</CODE>
<BR>
Get the static cardinality: this implementation is appropriate for [1] and [last()] which will always
return something if the input is non-empty</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> <A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../net/sf/saxon/expr/SingleItemFilter.html#optimize(net.sf.saxon.expr.parser.ExpressionVisitor, net.sf.saxon.expr.parser.ExpressionVisitor.ContextItemType)">optimize</A></B>(<A HREF="../../../../net/sf/saxon/expr/parser/ExpressionVisitor.html" title="class in net.sf.saxon.expr.parser">ExpressionVisitor</A> visitor,
<A HREF="../../../../net/sf/saxon/expr/parser/ExpressionVisitor.ContextItemType.html" title="class in net.sf.saxon.expr.parser">ExpressionVisitor.ContextItemType</A> contextItemType)</CODE>
<BR>
Perform optimisation of an expression and its subexpressions.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> <A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../net/sf/saxon/expr/SingleItemFilter.html#promote(net.sf.saxon.expr.parser.PromotionOffer, net.sf.saxon.expr.Expression)">promote</A></B>(<A HREF="../../../../net/sf/saxon/expr/parser/PromotionOffer.html" title="class in net.sf.saxon.expr.parser">PromotionOffer</A> offer,
<A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A> parent)</CODE>
<BR>
Promote this expression if possible</TD>
</TR>
</TABLE>
<A NAME="methods_inherited_from_class_net.sf.saxon.expr.UnaryExpression"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TH ALIGN="left"><B>Methods inherited from class net.sf.saxon.expr.<A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">UnaryExpression</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#computeSpecialProperties()">computeSpecialProperties</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#displayOperator(net.sf.saxon.Configuration)">displayOperator</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#equals(java.lang.Object)">equals</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#explain(net.sf.saxon.trace.ExpressionPresenter)">explain</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#getBaseExpression()">getBaseExpression</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#getItemType(net.sf.saxon.type.TypeHierarchy)">getItemType</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#hashCode()">hashCode</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#iterateSubExpressions()">iterateSubExpressions</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#replaceSubExpression(net.sf.saxon.expr.Expression, net.sf.saxon.expr.Expression)">replaceSubExpression</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#simplify(net.sf.saxon.expr.parser.ExpressionVisitor)">simplify</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#toString()">toString</A>, <A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#typeCheck(net.sf.saxon.expr.parser.ExpressionVisitor, net.sf.saxon.expr.parser.ExpressionVisitor.ContextItemType)">typeCheck</A></CODE></TD>
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</TABLE>
<A NAME="methods_inherited_from_class_net.sf.saxon.expr.Expression"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TH ALIGN="left"><B>Methods inherited from class net.sf.saxon.expr.<A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../net/sf/saxon/expr/Expression.html#addToPathMap(net.sf.saxon.expr.parser.PathMap, net.sf.saxon.expr.parser.PathMap.PathMapNodeSet)">addToPathMap</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#adoptChildExpression(net.sf.saxon.expr.Expression)">adoptChildExpression</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#checkForUpdatingSubexpressions()">checkForUpdatingSubexpressions</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#checkPermittedContents(net.sf.saxon.type.SchemaType, net.sf.saxon.expr.StaticContext, boolean)">checkPermittedContents</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#computeDependencies()">computeDependencies</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#computeStaticProperties()">computeStaticProperties</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#copy()">copy</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#doPromotion(net.sf.saxon.expr.Expression, net.sf.saxon.expr.parser.PromotionOffer)">doPromotion</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#dynamicError(java.lang.String, java.lang.String, net.sf.saxon.expr.XPathContext)">dynamicError</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#effectiveBooleanValue(net.sf.saxon.expr.XPathContext)">effectiveBooleanValue</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#evaluateAsString(net.sf.saxon.expr.XPathContext)">evaluateAsString</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#evaluateItem(net.sf.saxon.expr.XPathContext)">evaluateItem</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#evaluatePendingUpdates(net.sf.saxon.expr.XPathContext, net.sf.saxon.expr.PendingUpdateList)">evaluatePendingUpdates</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#explain(java.io.OutputStream)">explain</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getCardinality()">getCardinality</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getColumnNumber()">getColumnNumber</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getColumnNumber(long)">getColumnNumber</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getConstructType()">getConstructType</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getContainer()">getContainer</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getDependencies()">getDependencies</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getEvaluationMethod()">getEvaluationMethod</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getExecutable()">getExecutable</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getExpressionName()">getExpressionName</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getHostLanguage()">getHostLanguage</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getImplementationMethod()">getImplementationMethod</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getIntegerBounds()">getIntegerBounds</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getIntrinsicDependencies()">getIntrinsicDependencies</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getLineNumber()">getLineNumber</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getLineNumber(long)">getLineNumber</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getLocationId()">getLocationId</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getLocationProvider()">getLocationProvider</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getObjectName()">getObjectName</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getProperties()">getProperties</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getProperty(java.lang.String)">getProperty</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getPublicId()">getPublicId</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getSlotsUsed()">getSlotsUsed</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getSpecialProperties()">getSpecialProperties</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getSystemId()">getSystemId</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#getSystemId(long)">getSystemId</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#hasLoopingSubexpression(net.sf.saxon.expr.Expression)">hasLoopingSubexpression</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#hasVariableBinding(net.sf.saxon.expr.Binding)">hasVariableBinding</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#implementsStaticTypeCheck()">implementsStaticTypeCheck</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#isSubtreeExpression()">isSubtreeExpression</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#isUpdatingExpression()">isUpdatingExpression</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#isVacuousExpression()">isVacuousExpression</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#iterate(net.sf.saxon.expr.XPathContext)">iterate</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#iterateEvents(net.sf.saxon.expr.XPathContext)">iterateEvents</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#iterateSameFocusSubExpressions()">iterateSameFocusSubExpressions</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#markTailFunctionCalls(net.sf.saxon.om.StructuredQName, int)">markTailFunctionCalls</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#process(net.sf.saxon.expr.XPathContext)">process</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#resetLocalStaticProperties()">resetLocalStaticProperties</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#setContainer(net.sf.saxon.expr.Container)">setContainer</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#setEvaluationMethod(int)">setEvaluationMethod</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#setFiltered(boolean)">setFiltered</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#setFlattened(boolean)">setFlattened</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#setLocationId(int)">setLocationId</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#staticTypeCheck(net.sf.saxon.value.SequenceType, boolean, net.sf.saxon.expr.parser.RoleLocator, net.sf.saxon.TypeCheckerEnvironment)">staticTypeCheck</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#suppressValidation(int)">suppressValidation</A>, <A HREF="../../../../net/sf/saxon/expr/Expression.html#typeError(java.lang.String, java.lang.String, net.sf.saxon.expr.XPathContext)">typeError</A></CODE></TD>
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<TH ALIGN="left"><B>Methods inherited from class java.lang.<A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#clone()" title="class or interface in java.lang">clone</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#finalize()" title="class or interface in java.lang">finalize</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#getClass()" title="class or interface in java.lang">getClass</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notify()" title="class or interface in java.lang">notify</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notifyAll()" title="class or interface in java.lang">notifyAll</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait()" title="class or interface in java.lang">wait</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long)" title="class or interface in java.lang">wait</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long, int)" title="class or interface in java.lang">wait</A></CODE></TD>
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<P>
<!-- ========= CONSTRUCTOR DETAIL ======== -->
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<B>Constructor Detail</B></FONT></TH>
</TR>
</TABLE>
<A NAME="SingleItemFilter()"><!-- --></A><H3>
SingleItemFilter</H3>
<PRE>
public <B>SingleItemFilter</B>()</PRE>
<DL>
</DL>
<!-- ============ METHOD DETAIL ========== -->
<A NAME="method_detail"><!-- --></A>
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<A NAME="optimize(net.sf.saxon.expr.parser.ExpressionVisitor, net.sf.saxon.expr.parser.ExpressionVisitor.ContextItemType)"><!-- --></A><H3>
optimize</H3>
<PRE>
public <A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A> <B>optimize</B>(<A HREF="../../../../net/sf/saxon/expr/parser/ExpressionVisitor.html" title="class in net.sf.saxon.expr.parser">ExpressionVisitor</A> visitor,
<A HREF="../../../../net/sf/saxon/expr/parser/ExpressionVisitor.ContextItemType.html" title="class in net.sf.saxon.expr.parser">ExpressionVisitor.ContextItemType</A> contextItemType)
throws <A HREF="../../../../net/sf/saxon/trans/XPathException.html" title="class in net.sf.saxon.trans">XPathException</A></PRE>
<DL>
<DD>Perform optimisation of an expression and its subexpressions.
<p/>
<p>This method is called after all references to functions and variables have been resolved
to the declaration of the function or variable, and after all type checking has been done.</p>
<P>
<DD><DL>
<DT><B>Overrides:</B><DD><CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#optimize(net.sf.saxon.expr.parser.ExpressionVisitor, net.sf.saxon.expr.parser.ExpressionVisitor.ContextItemType)">optimize</A></CODE> in class <CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">UnaryExpression</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>visitor</CODE> - an expresion visitor<DD><CODE>contextItemType</CODE> - the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
<A HREF="../../../../net/sf/saxon/type/Type.html#ITEM_TYPE"><CODE>Type.ITEM_TYPE</CODE></A>
<DT><B>Returns:</B><DD>the original expression, rewritten if appropriate to optimize execution
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../../../net/sf/saxon/trans/XPathException.html" title="class in net.sf.saxon.trans">XPathException</A></CODE> - if an error is discovered during this phase
(typically a type error)</DL>
</DD>
</DL>
<HR>
<A NAME="promote(net.sf.saxon.expr.parser.PromotionOffer, net.sf.saxon.expr.Expression)"><!-- --></A><H3>
promote</H3>
<PRE>
public <A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A> <B>promote</B>(<A HREF="../../../../net/sf/saxon/expr/parser/PromotionOffer.html" title="class in net.sf.saxon.expr.parser">PromotionOffer</A> offer,
<A HREF="../../../../net/sf/saxon/expr/Expression.html" title="class in net.sf.saxon.expr">Expression</A> parent)
throws <A HREF="../../../../net/sf/saxon/trans/XPathException.html" title="class in net.sf.saxon.trans">XPathException</A></PRE>
<DL>
<DD>Promote this expression if possible
<P>
<DD><DL>
<DT><B>Overrides:</B><DD><CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#promote(net.sf.saxon.expr.parser.PromotionOffer, net.sf.saxon.expr.Expression)">promote</A></CODE> in class <CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">UnaryExpression</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>offer</CODE> - details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expression<DD><CODE>parent</CODE> - the containing expression in the expression tree
<DT><B>Returns:</B><DD>if the offer is not accepted, return this expression unchanged.
Otherwise return the result of rewriting the expression to promote
this subexpression
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../../../net/sf/saxon/trans/XPathException.html" title="class in net.sf.saxon.trans">XPathException</A></CODE> - if any error is detected</DL>
</DD>
</DL>
<HR>
<A NAME="computeCardinality()"><!-- --></A><H3>
computeCardinality</H3>
<PRE>
public int <B>computeCardinality</B>()</PRE>
<DL>
<DD>Get the static cardinality: this implementation is appropriate for [1] and [last()] which will always
return something if the input is non-empty
<P>
<DD><DL>
<DT><B>Overrides:</B><DD><CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html#computeCardinality()">computeCardinality</A></CODE> in class <CODE><A HREF="../../../../net/sf/saxon/expr/UnaryExpression.html" title="class in net.sf.saxon.expr">UnaryExpression</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Returns:</B><DD>the computed cardinality, as one of the values <A HREF="../../../../net/sf/saxon/expr/StaticProperty.html#ALLOWS_ZERO_OR_ONE"><CODE>StaticProperty.ALLOWS_ZERO_OR_ONE</CODE></A>,
<A HREF="../../../../net/sf/saxon/expr/StaticProperty.html#EXACTLY_ONE"><CODE>StaticProperty.EXACTLY_ONE</CODE></A>, <A HREF="../../../../net/sf/saxon/expr/StaticProperty.html#ALLOWS_ONE_OR_MORE"><CODE>StaticProperty.ALLOWS_ONE_OR_MORE</CODE></A>,
<A HREF="../../../../net/sf/saxon/expr/StaticProperty.html#ALLOWS_ZERO_OR_MORE"><CODE>StaticProperty.ALLOWS_ZERO_OR_MORE</CODE></A></DL>
</DD>
</DL>
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