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net.sf.saxon.expr.flwor
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<H2>
Package net.sf.saxon.expr.flwor
</H2>
This package contains classes responsible for evaluation of FLWOR expressions, in particular,
those clauses of FLWOR expressions that are supported in Saxon-HE.
<P>
<B>See:</B>
<BR>
<A HREF="#package_description"><B>Description</B></A>
<P>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
<B>Interface Summary</B></FONT></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ExpressionProcessor.html" title="interface in net.sf.saxon.expr.flwor">ExpressionProcessor</A></B></TD>
<TD> </TD>
</TR>
</TABLE>
<P>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
<B>Class Summary</B></FONT></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/Clause.html" title="class in net.sf.saxon.expr.flwor">Clause</A></B></TD>
<TD>A "Clause" refers specifically to one of the clauses of a FLWOR expression, for example the "for"
clause, the "let" clause, the "where" or "order by" clause.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/FLWORExpression.html" title="class in net.sf.saxon.expr.flwor">FLWORExpression</A></B></TD>
<TD>This class represents a FLWOR expression, evaluated using tuple streams</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ForClause.html" title="class in net.sf.saxon.expr.flwor">ForClause</A></B></TD>
<TD>A "for" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ForClauseOuterPull.html" title="class in net.sf.saxon.expr.flwor">ForClauseOuterPull</A></B></TD>
<TD>This class represents the tuple stream returned by a "for" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ForClauseOuterPush.html" title="class in net.sf.saxon.expr.flwor">ForClauseOuterPush</A></B></TD>
<TD>This class implements the changes to the tuple stream effected by a "for" clause in a FLWOR expression
where "allowing empty" is specified</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ForClausePull.html" title="class in net.sf.saxon.expr.flwor">ForClausePull</A></B></TD>
<TD>This class implements the changes to the tuple stream effected by a "for" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ForClausePush.html" title="class in net.sf.saxon.expr.flwor">ForClausePush</A></B></TD>
<TD>This class implements the changes to the tuple stream effected by a "for" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/LetClause.html" title="class in net.sf.saxon.expr.flwor">LetClause</A></B></TD>
<TD>A "let" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/LetClausePull.html" title="class in net.sf.saxon.expr.flwor">LetClausePull</A></B></TD>
<TD>Implements the changes to a tuple stream effected by the Let clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/LetClausePush.html" title="class in net.sf.saxon.expr.flwor">LetClausePush</A></B></TD>
<TD>Implements the changes to a tuple stream effected by the Let clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/LocalVariableBinding.html" title="class in net.sf.saxon.expr.flwor">LocalVariableBinding</A></B></TD>
<TD>Represents the defining occurrence of a variable declared within a FLWOR expression,
for example the $p in "for $x at $p in ...".</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/OrderByClause.html" title="class in net.sf.saxon.expr.flwor">OrderByClause</A></B></TD>
<TD>This class represents an "order by" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/OrderByClausePull.html" title="class in net.sf.saxon.expr.flwor">OrderByClausePull</A></B></TD>
<TD>Represents the tuple stream delivered by an "order by" clause.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/OrderByClausePush.html" title="class in net.sf.saxon.expr.flwor">OrderByClausePush</A></B></TD>
<TD>Represents the tuple stream delivered by an "order by" clause.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ReturnClauseIterator.html" title="class in net.sf.saxon.expr.flwor">ReturnClauseIterator</A></B></TD>
<TD>This iterator applies the return expression of a FLWOR expression to each
of the tuples in a supplied tuple stream, returning the result as an iterator</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/ReturnClausePush.html" title="class in net.sf.saxon.expr.flwor">ReturnClausePush</A></B></TD>
<TD>The class represents the final stage in a push-mode tuple pipeline.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/SingularityPull.html" title="class in net.sf.saxon.expr.flwor">SingularityPull</A></B></TD>
<TD>The "singularity" tuple stream delivers a single empty tuple.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/Tuple.html" title="class in net.sf.saxon.expr.flwor">Tuple</A></B></TD>
<TD>A tuple, as it appears in an XQuery tuple stream handled by extended FLWOR expressions.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/TupleExpression.html" title="class in net.sf.saxon.expr.flwor">TupleExpression</A></B></TD>
<TD>A tuple expression is an expression that returns a tuple.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/TuplePull.html" title="class in net.sf.saxon.expr.flwor">TuplePull</A></B></TD>
<TD>Abtract class representing a tuple stream (used to evaluate a FLWOR expression) in pull mode
(where the consumer of tuples activates the provider of those tuples)</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/TuplePush.html" title="class in net.sf.saxon.expr.flwor">TuplePush</A></B></TD>
<TD>Abtract class representing a tuple stream (used to evaluate a FLWOR expression) in push mode
(where the provider of tuples activates the consumer of those tuples)</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/WhereClause.html" title="class in net.sf.saxon.expr.flwor">WhereClause</A></B></TD>
<TD>A "where" clause in a FLWOR expression</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/WhereClausePull.html" title="class in net.sf.saxon.expr.flwor">WhereClausePull</A></B></TD>
<TD>This class represents the tuple stream delivered as the output of a where clause in a
FLWOR expression: that is, it returns all the tuples in its input stream that satisfy
a specified predicate.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD WIDTH="15%"><B><A HREF="../../../../../net/sf/saxon/expr/flwor/WhereClausePush.html" title="class in net.sf.saxon.expr.flwor">WhereClausePush</A></B></TD>
<TD>This class represents the tuple stream delivered as the output of a where clause in a
FLWOR expression: that is, it supplies all the tuples in its input stream that satisfy
a specified predicate.</TD>
</TR>
</TABLE>
<P>
<A NAME="package_description"><!-- --></A><H2>
Package net.sf.saxon.expr.flwor Description
</H2>
<P>
<p>This package contains classes responsible for evaluation of FLWOR expressions, in particular,
those clauses of FLWOR expressions that are supported in Saxon-HE.</p>
<p>FLWOR expressions are implemented as a pipeline of clauses, much as described in the specification.
The pipeline can be evaluated in push or pull mode: in push mode, the supplier of tuples activates the consumer
of tuples when a tuple is ready to be processed, while in pull mode, the consumer of tuples calls the supplier
to request the next tuple. In both cases the "tuple" is not actually passed as an argument or result of this call,
but is represented by the state of local variables in the XPathContext stack on completion of the call. The only
time tuples are represented as real objects is when the processing is not pipelined, for example when tuples need
to be sorted or grouped.</p>
<p>Simple "for" and "let" expressions do not use this mechanism: instead, they are compiled to a
ForExpression or LetExpression.</p>
<p align="center"><i>Michael H. Kay<br/>
Saxonica Limited<br/>
28 November 2011</i></p>
<P>
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