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he / tags / 9.7.0.3 / hej / net / sf / saxon / expr / flwor / package.html @ cb770b3c

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<!-- Copyright (c) 2014 Saxonica Limited. -->
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<html>
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<head>
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    <title>Package overview: net.sf.saxon.expr.flwor</title>
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</head>
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<body>
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<p>This package contains classes responsible for evaluation of FLWOR expressions, in particular,
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    those clauses of FLWOR expressions that are supported in Saxon-HE.</p>
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<p>FLWOR expressions are implemented as a pipeline of clauses, much as described in the specification.
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    The pipeline can be evaluated in push or pull mode: in push mode, the supplier of tuples activates the consumer
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    of tuples when a tuple is ready to be processed, while in pull mode, the consumer of tuples calls the supplier
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    to request the next tuple. In both cases the "tuple" is not actually passed as an argument or result of this call,
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    but is represented by the state of local variables in the XPathContext stack on completion of the call. The only
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    time tuples are represented as real objects is when the processing is not pipelined, for example when tuples need
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    to be sorted or grouped.</p>
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<p>Simple "for" and "let" expressions do not use this mechanism: instead, they are compiled to a
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    ForExpression or LetExpression.</p>
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<p align="center"><i>Michael H. Kay<br/>
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    Saxonica Limited<br/>
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    28 November 2011</i></p>
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</body>
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</html>
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