Package net.sf.saxon.expr.flwor
package net.sf.saxon.expr.flwor
This package contains classes responsible for evaluation of FLWOR expressions.
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.
Simple "for" and "let" expressions do not use this mechanism: instead, they are compiled to a
ForExpression or LetExpression.
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ClassDescriptionA "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.A "trace" clause in a FLWOR expression, added by a TraceCodeInjectorA "count" clause in a FLWOR expressionA tuple stream that implements a "count" clause in an XQuery 3.0 FLWOR expressionA tuple stream in push mode that implements a "count" clause in an XQuery 3.0 FLWOR expressionA "let" clause in a FLWOR expressionImplements the trace clause in a FLWOR expression.Implements the changes to a tuple stream effected by the Let clause in a FLWOR expressionThis class represents a FLWOR expression, evaluated using tuple streamsA "for" clause in a FLWOR expressionThis class represents the tuple stream returned by a "for" clause in a FLWOR expressionThis class implements the changes to the tuple stream effected by a "for" clause in a FLWOR expression where "allowing empty" is specifiedThis class implements the changes to the tuple stream effected by a "for" clause in a FLWOR expressionThis class implements the changes to the tuple stream effected by a "for" clause in a FLWOR expressionThis class represents an "group by" clause in a FLWOR expressionInner class representing the contents of a tuple from the pre-grouping tuple stream; a set of such objects consitutes a group.Inner class representing a tuple comparison key: that is, an arbitrary object whose equals() and hashCode() methods can be used to test whether two tuples have equivalent grouping keysRepresents the tuple stream delivered by an "group by" clause.Represents the tuple stream delivered by an "group by" clause.A "let" clause in a FLWOR expressionImplements the changes to a tuple stream effected by the Let clause in a FLWOR expressionImplements the changes to a tuple stream effected by the Let clause in a FLWOR expressionRepresents the defining occurrence of a variable declared within a FLWOR expression, for example the $p in "for $x at $p in ...".Interface representing a visitor of the clauses of a FLWOR expression that can process and modify the operands of each clauseThis class represents an "order by" clause in a FLWOR expressionRepresents the tuple stream delivered by an "order by" clause.Represents the tuple stream delivered by an "order by" clause.Expression class that implements the "outer for" clause of XQuery 3.0An elaborator for a "for" expression, typically written as {for $x in SEQ return R}.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 iteratorThe class represents the final stage in a push-mode tuple pipeline.The "singularity" tuple stream delivers a single empty tuple.A "trace" clause in a FLWOR expression, added by a TraceCodeInjector for diagnostic tracing, debugging, profiling or similar purposes.This class represents the tuple stream delivered as the output of a trace clause in a FLWOR expression.This class represents the tuple stream delivered as the output of a trace clause in a FLWOR expression.A tuple, as it appears in an XQuery tuple stream handled by extended FLWOR expressions.A tuple expression is an expression that returns a FLWOR tuple.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)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)A "where" clause in a FLWOR expressionThis 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.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.A "where" clause in a FLWOR expressionThis class represents the tuple stream delivered as the output of a while clause in a FLWOR expression: that is, it returns all the tuples in its input stream that satisfy a specified predicate, until it finds one that doesn't.This class represents the tuple stream delivered as the output of a while clause in a FLWOR expression: that is, it supplies all the tuples in its input stream that satisfy a specified predicate until it finds one that doesn't.Implements an XQuery 3.0 sliding or tumbling window clause within a FLWOR expressionInformation about a window: the items making up the window, as well as the variables relating to the start and end of the window, and the status of the winoow in relation to the processing of the current input sequence.Implement a sliding or tumbling window clause of a FLWOR expression in tuple-pull mode.Implement a sliding or tumbling window clause of a FLWOR expression in tuple-push mode.