net.sf.saxon.expr.sort

Class DocumentSorter

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.UnaryExpression

net.sf.saxon.expr.sort.DocumentSorter

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable

public class DocumentSorter
extends UnaryExpression

A DocumentSorter is an expression that sorts a sequence of nodes into document order.

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
DocumentSorter(Expression base)
DocumentSorter(Expression base, boolean intraDocument)

Method Summary

Modifier and Type	Method and Description
int	computeSpecialProperties() Get the static properties of this expression (other than its type).
Expression	copy(RebindingMap rebindings) Copy an expression.
boolean	effectiveBooleanValue(XPathContext context) Get the effective boolean value of the expression.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
ItemOrderComparer	getComparer()
java.lang.String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
int	getNetCost() Return the net cost of evaluating this expression, excluding the cost of evaluating its operands.
protected OperandRole	getOperandRole() Get the usage (in terms of streamability analysis) of the single operand
java.lang.String	getStreamerName() Get the (partial) name of a class that supports streaming of this kind of expression
SequenceIterator<?>	iterate(XPathContext context) Return an Iterator to iterate over the values of a sequence.
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform optimisation of an expression and its subexpressions.
Expression	simplify() Simplify an expression.
Pattern	toPattern(Configuration config) Convert this expression to an equivalent XSLT pattern
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression.
Expression	unordered(boolean retainAllNodes, boolean forStreaming) Replace this expression by a simpler expression that delivers the results without regard to order.

Methods inherited from class net.sf.saxon.expr.UnaryExpression

computeCardinality, computeHashCode, displayOperator, equals, getBaseExpression, getItemType, getOperand, operands, setBaseExpression, toShortString, toString

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, typeCheckChildren, typeError, verifyParentPointers

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DocumentSorter

public DocumentSorter(Expression base)

DocumentSorter

public DocumentSorter(Expression base,
                      boolean intraDocument)

Method Detail

getOperandRole

protected OperandRole getOperandRole()

Description copied from class: UnaryExpression

Get the usage (in terms of streamability analysis) of the single operand

Specified by:

getOperandRole in class UnaryExpression

Returns:

the operand usage

getExpressionName

public java.lang.String getExpressionName()

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class Expression

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

getComparer

public ItemOrderComparer getComparer()

simplify

public Expression simplify()
                    throws XPathException

Description copied from class: Expression

Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation simplifies its operands.

Overrides:

simplify in class Expression

Returns:

the simplified expression (or the original if unchanged, or if modified in-situ)

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException

Description copied from class: UnaryExpression

Type-check the expression. Default implementation for unary operators that accept any kind of operand

Overrides:

typeCheck in class UnaryExpression

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextInfo)
                    throws XPathException

Description copied from class: UnaryExpression

Perform optimisation of an expression and its subexpressions.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:

optimize in class UnaryExpression

Parameters:

visitor - an expression visitor

contextInfo - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

getNetCost

public int getNetCost()

Return the net cost of evaluating this expression, excluding the cost of evaluating its operands. We take the cost of evaluating a simple scalar comparison or arithmetic expression as 1 (one).

Overrides:

getNetCost in class Expression

Returns:

the intrinsic cost of this operation, excluding the costs of evaluating the operands

unordered

public Expression unordered(boolean retainAllNodes,
                            boolean forStreaming)
                     throws XPathException

Replace this expression by a simpler expression that delivers the results without regard to order.

Overrides:

unordered in class Expression

Parameters:

retainAllNodes - set to true if the result must contain exactly the same nodes as the original; set to false if the result can eliminate (or introduce) duplicates.

forStreaming - set to true if optimizing for streaming

Returns:

an expression that delivers the same nodes in a more convenient order

Throws:

XPathException - if the rewrite fails

computeSpecialProperties

public int computeSpecialProperties()

Description copied from class: UnaryExpression

Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.

Overrides:

computeSpecialProperties in class UnaryExpression

Returns:

the special properties, as a bit-significant integer

copy

public Expression copy(RebindingMap rebindings)

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Parameters:

rebindings - variables that need to be re-bound

Returns:

the copy of the original expression

toPattern

public Pattern toPattern(Configuration config)
                  throws XPathException

Convert this expression to an equivalent XSLT pattern

Overrides:

toPattern in class Expression

Parameters:

config - the Saxon configuration

Returns:

the equivalent pattern

Throws:

XPathException - if conversion is not possible

getImplementationMethod

public int getImplementationMethod()

An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.

Specified by:

getImplementationMethod in class Expression

Returns:

the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

iterate

public SequenceIterator<?> iterate(XPathContext context)
                            throws XPathException

Description copied from class: Expression

Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.

Overrides:

iterate in class Expression

Parameters:

context - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Description copied from class: Expression

Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.

Overrides:

effectiveBooleanValue in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the effective boolean value

Throws:

XPathException - if any dynamic error occurs evaluating the expression

export

public void export(ExpressionPresenter out)
            throws XPathException

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

export in interface ExportAgent

Overrides:

export in class UnaryExpression

Parameters:

out - the expression presenter used to display the structure

Throws:

XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

getStreamerName

public java.lang.String getStreamerName()

Get the (partial) name of a class that supports streaming of this kind of expression

Overrides:

getStreamerName in class Expression

Returns:

the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class