net.sf.saxon.ma.arrays

Class ArrayBlock

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.ma.arrays.ArrayBlock

All Implemented Interfaces:

IdentityComparable

public class ArrayBlock
extends Expression

An expression that delivers a fixed size array whose members are the result of evaluating corresponding expressions: [a,b,c,d]

Field Summary

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

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

Constructor Summary

Constructors

Constructor and Description
ArrayBlock(List<Expression> children) Create an empty block

Method Summary

Methods

Modifier and Type	Method and Description
int	computeCardinality() Determine the cardinality of the expression
int	computeSpecialProperties() Compute the special properties of this expression.
Expression	copy() Copy an expression.
boolean	createsNewNodes() Determine whether this instruction creates new nodes.
boolean	equals(Object other) Is this expression the same as another expression?
Item	evaluateItem(XPathContext context) Evaluate an expression as a single item.
void	export(ExpressionPresenter out) Diagnostic print of expression structure.
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Block expression
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().
ItemType	getItemType() Determine the data type of the items returned by this expression
OperandArray	getOperanda() Get the data structure holding the operands of this expression.
BlockAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this expression
int	hashCode() Hashcode supporting equals()
Iterable<Operand>	operands() Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
protected void	setOperanda(OperandArray operanda) Set the data structure for the operands of this expression.
String	toShortString() Produce a short string identifying the expression for use in error messages

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

addToPathMap, adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getPosture, getPostureAndSweepIfKnown, getProperties, getProperty, getRetainedStaticContext, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStreamability, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, operandSparseList, optimize, optimizeChildren, optimizeForType, process, promote, promoteChildren, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setFiltered, setFlattened, setLocation, setParentExpression, setPostureAndSweep, setRetainedStaticContext, setRetainedStaticContextLocally, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, toString, typeCheck, typeCheckChildren, typeError, unordered

Methods inherited from class java.lang.Object

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

Constructor Detail

ArrayBlock

public ArrayBlock(List<Expression> children)

Create an empty block

Method Detail

setOperanda

protected void setOperanda(OperandArray operanda)

Set the data structure for the operands of this expression. This must be created during initialisation of the expression and must not be subsequently changed

Parameters:

operanda - the data structure for expression operands

getOperanda

public OperandArray getOperanda()

Get the data structure holding the operands of this expression.

Returns:

the data structure holding expression operands

operands

public Iterable<Operand> operands()

Description copied from class: Expression

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

Overrides:

operands in class Expression

Returns:

an iterator containing the sub-expressions of this expression

getExpressionName

public String getExpressionName()

Description copied from class: Expression

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 export() output displaying the expression.

computeSpecialProperties

public int computeSpecialProperties()

Description copied from class: Expression

Compute the special properties of this expression. These properties are denoted by a bit-significant integer, possible values are in class StaticProperty. The "special" properties are properties other than cardinality and dependencies, and most of them relate to properties of node sequences, for example whether the nodes are in document order.

Overrides:

computeSpecialProperties in class Expression

Returns:

the special properties, as a bit-significant integer

equals

public boolean equals(Object other)

Is this expression the same as another expression?

Overrides:

equals in class Object

Parameters:

other - the expression to be compared with this one

Returns:

true if the two expressions are statically equivalent

hashCode

public int hashCode()

Hashcode supporting equals()

Overrides:

hashCode in class Object

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

getItemType

public final ItemType getItemType()

Determine the data type of the items returned by this expression

Specified by:

getItemType in class Expression

Returns:

the data type

computeCardinality

public final int computeCardinality()

Determine the cardinality of the expression

Specified by:

computeCardinality in class Expression

Returns:

the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE

createsNewNodes

public final boolean createsNewNodes()

Determine whether this instruction creates new nodes. This implementation returns true if any child instruction returns true.

export

public void export(ExpressionPresenter out)

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

Specified by:

export in class Expression

Parameters:

out - the expression presenter used to display the structure

toShortString

public String toShortString()

Description copied from class: Expression

Produce a short string identifying the expression for use in error messages

Overrides:

toShortString in class Expression

Returns:

a short string, sufficient to identify the expression

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. This implementation provides both iterate() and process() methods natively.

Specified by:

getImplementationMethod in class Expression

Returns:

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

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.

Overrides:

evaluateItem in class Expression

Parameters:

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

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Block expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

getStreamingAdjunct

public BlockAdjunct getStreamingAdjunct()

Get a class that supports streamed evaluation of this expression

Overrides:

getStreamingAdjunct in class Expression

Returns:

the relevant StreamingAdjunct, or null if none is available