org.exist.xquery
Class FilteredExpression

java.lang.Object
  org.exist.xquery.AbstractExpression
      org.exist.xquery.FilteredExpression

All Implemented Interfaces:

Expression

public class FilteredExpression
extends AbstractExpression

FilteredExpression represents a primary expression with a predicate. Examples: for $i in (1 to 10)[$i mod 2 = 0], $a[1], (doc("test.xml")//section)[2]. Other predicate expressions are handled by class LocationStep.

Field Summary

protected boolean	abbreviated
protected Expression	expression
protected java.util.List<Predicate>	predicates

Fields inherited from class org.exist.xquery.AbstractExpression

column, context, contextDocSet, contextId, line, unordered

Fields inherited from interface org.exist.xquery.Expression

DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_NODE_CONSTRUCTOR, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NEED_INDEX_INFO, NO_CONTEXT_ID, NON_STREAMABLE, POSITIONAL_PREDICATE, SINGLE_STEP_EXECUTION, UNORDERED, USE_TREE_TRAVERSAL

Constructor Summary

FilteredExpression(XQueryContext context, Expression expr)

Method Summary

void	accept(ExpressionVisitor visitor) Start traversing the expression tree using the specified ExpressionVisitor.
void	addPredicate(Predicate pred)
void	analyze(AnalyzeContextInfo contextInfo) Statically analyze the expression and its subexpressions.
void	dump(ExpressionDumper dumper) Write a diagnostic dump of the expression to the passed ExpressionDumper.
Sequence	eval(Sequence contextSequence, Item contextItem) Evaluate the expression represented by this object.
int	getDependencies() Returns Dependency.DEFAULT_DEPENDENCIES.
Expression	getExpression()
Expression	getParent()
java.util.List<Predicate>	getPredicates()
int	getPrimaryAxis()
void	resetState(boolean postOptimization) Called to inform an expression that it should reset to its initial state.
int	returnsType() The static return type of the expression.
void	setAbbreviated(boolean abbrev)
void	setPrimaryAxis(int axis)
java.lang.String	toString()

Methods inherited from class org.exist.xquery.AbstractExpression

allowMixNodesInReturn, eval, getCardinality, getColumn, getContext, getContextDocSet, getContextId, getExpressionId, getLine, getSource, getSubExpression, getSubExpressionCount, match, needsReset, setASTNode, setContextDocSet, setContextId, setLocation, simplify

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

expression

protected final Expression expression

abbreviated

protected boolean abbreviated

predicates

protected final java.util.List<Predicate> predicates

Constructor Detail

FilteredExpression

public FilteredExpression(XQueryContext context,
                          Expression expr)

Parameters:

context -

Method Detail

addPredicate

public void addPredicate(Predicate pred)

getPredicates

public java.util.List<Predicate> getPredicates()

getExpression

public Expression getExpression()

analyze

public void analyze(AnalyzeContextInfo contextInfo)
             throws XPathException

Description copied from interface: Expression

Statically analyze the expression and its subexpressions. During the static analysis phase, the query engine can detect unknown variables and some type errors.

Throws:

XPathException

eval

public Sequence eval(Sequence contextSequence,
                     Item contextItem)
              throws XPathException

Description copied from interface: Expression

Evaluate the expression represented by this object. Depending on the context in which this expression is executed, either the context sequence, the context item or both of them may be set. An implementing class should know how to handle this. The general contract is as follows: if the Dependency.CONTEXT_ITEM bit is set in the bit field returned by Expression.getDependencies(), the eval method will be called once for every item in the context sequence. The contextItem parameter will be set to the current item. Otherwise, the eval method will only be called once for the whole context sequence and contextItem will be null. eXist tries to process the entire context set in one, single step whenever possible. Thus, most classes only expect context to contain a list of nodes which represents the current context of the expression. The position() function in XPath is an example for an expression, which requires both, context sequence and context item to be set. The context sequence might be a node set, a sequence of atomic values or a single node or atomic value.

Specified by:

eval in interface Expression

Specified by:

eval in class AbstractExpression

Parameters:

contextSequence - the current context sequence.

contextItem - a single item, taken from context. This defines the item, the expression should work on.

Throws:

XPathException

dump

public void dump(ExpressionDumper dumper)

Description copied from interface: Expression

Write a diagnostic dump of the expression to the passed ExpressionDumper.

Parameters:

dumper - the expression dumper to write to

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

returnsType

public int returnsType()

Description copied from interface: Expression

The static return type of the expression. This method should return one of the type constants defined in class Type. If the return type cannot be determined statically, return Type.ITEM.

Specified by:

returnsType in interface Expression

Specified by:

returnsType in class AbstractExpression

resetState

public void resetState(boolean postOptimization)

Description copied from interface: Expression

Called to inform an expression that it should reset to its initial state. All cached data in the expression object should be dropped. For example, the xmldb:document() function calls this method whenever the input document set has changed.

Specified by:

resetState in interface Expression

Overrides:

resetState in class AbstractExpression

setPrimaryAxis

public void setPrimaryAxis(int axis)

Specified by:

setPrimaryAxis in interface Expression

Overrides:

setPrimaryAxis in class AbstractExpression

getPrimaryAxis

public int getPrimaryAxis()

Specified by:

getPrimaryAxis in interface Expression

Overrides:

getPrimaryAxis in class AbstractExpression

setAbbreviated

public void setAbbreviated(boolean abbrev)

getDependencies

public int getDependencies()

Description copied from class: AbstractExpression

Returns Dependency.DEFAULT_DEPENDENCIES.

Specified by:

getDependencies in interface Expression

Overrides:

getDependencies in class AbstractExpression

Returns:

set of bit-flags

See Also:

Expression.getDependencies()

accept

public void accept(ExpressionVisitor visitor)

Description copied from interface: Expression

Start traversing the expression tree using the specified ExpressionVisitor.

Specified by:

accept in interface Expression

Overrides:

accept in class AbstractExpression

getParent

public Expression getParent()

Specified by:

getParent in interface Expression

Overrides:

getParent in class AbstractExpression