org.exist.xquery
Class ExtensionExpression

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

All Implemented Interfaces:

Expression

public class ExtensionExpression
extends AbstractExpression

Implements an XQuery extension expression. An extension expression starts with a list of pragmas, followed by an expression enclosed in curly braces. For evaluation details check {eval(Sequence, Item).

Field Summary

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

ExtensionExpression(XQueryContext context)

Method Summary

void	accept(ExpressionVisitor visitor) Start traversing the expression tree using the specified ExpressionVisitor.
void	addPragma(Pragma pragma)
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) For every pragma in the list, calls Pragma.before(XQueryContext, Expression) before evaluation.
int	getCardinality() The default cardinality is Cardinality.EXACTLY_ONE.
int	getDependencies() Returns Dependency.DEFAULT_DEPENDENCIES.
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	setContextDocSet(DocumentSet contextSet)
void	setExpression(Expression inner)
void	setPrimaryAxis(int axis)

Methods inherited from class org.exist.xquery.AbstractExpression

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

Methods inherited from class java.lang.Object

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

Constructor Detail

ExtensionExpression

public ExtensionExpression(XQueryContext context)

Method Detail

setExpression

public void setExpression(Expression inner)

addPragma

public void addPragma(Pragma pragma)

eval

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

For every pragma in the list, calls Pragma.before(XQueryContext, Expression) before evaluation. The method then tries to call Pragma.eval(Sequence, Item) on every pragma. If a pragma does not return null for this call, the returned Sequence will become the result of the extension expression. If more than one pragma returns something for eval, an exception will be thrown. If all pragmas return null, we call eval on the original expression and return that.

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

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

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

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

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()

getCardinality

public int getCardinality()

Description copied from class: AbstractExpression

The default cardinality is Cardinality.EXACTLY_ONE.

Specified by:

getCardinality in interface Expression

Overrides:

getCardinality in class AbstractExpression

setContextDocSet

public void setContextDocSet(DocumentSet contextSet)

Specified by:

setContextDocSet in interface Expression

Overrides:

setContextDocSet 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

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

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