com.saxonica.ee.stream

Class Streamability

java.lang.Object

com.saxonica.ee.stream.Streamability

public class Streamability
extends Object

Supporting class for assessing the streamability of expressions. Among other things, it contains an implementation of the General Streamability Rules.

Field Summary

Fields

Modifier and Type	Field and Description
static int	EXTENDED
static int	OFF
static int	STANDARD

Constructor Summary

Constructors

Constructor and Description
Streamability()

Method Summary

Methods

Modifier and Type	Method and Description
static PostureAndSweep	generalStreamabilityRules(Expression target, Iterable<Operand> operands, boolean allowExtensions, ContextItemStaticInfo contextInfo, List<String> reasons) Implement the general streamability rules; the rules used to determine the posture and sweep of any expression except when more specific rules are defined for that class of expression
static Operand	getConsumingOperand(Expression exp) Get the consuming (or potentially consuming) operand of an expression, assuming there is exactly one
static boolean	isChildlessNodeKind(ItemType type) Ask whether an ItemType only allows nodes that cannot have children
static Expression	rewriteForExpressionAsMappingExpression(ForExpression forEx)
static Expression	rewriteQuantifiedExpressionAsFilterExpression(QuantifiedExpression quant)

Methods inherited from class java.lang.Object

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

Field Detail

OFF

public static final int OFF

See Also:

Constant Field Values

STANDARD

public static final int STANDARD

See Also:

Constant Field Values

EXTENDED

public static final int EXTENDED

See Also:

Constant Field Values

Constructor Detail

Streamability

public Streamability()

Method Detail

getConsumingOperand

public static Operand getConsumingOperand(Expression exp)

Get the consuming (or potentially consuming) operand of an expression, assuming there is exactly one

Parameters:

exp - the expression

Returns:

if there are one or more consuming subexpressions, then the first of these; otherwise, null. Also returns null if the posture and sweep have not yet been assessed.

rewriteQuantifiedExpressionAsFilterExpression

public static Expression rewriteQuantifiedExpressionAsFilterExpression(QuantifiedExpression quant)
                                                                throws XPathException

Throws:

XPathException

rewriteForExpressionAsMappingExpression

public static Expression rewriteForExpressionAsMappingExpression(ForExpression forEx)

generalStreamabilityRules

public static PostureAndSweep generalStreamabilityRules(Expression target,
                                        Iterable<Operand> operands,
                                        boolean allowExtensions,
                                        ContextItemStaticInfo contextInfo,
                                        List<String> reasons)

Implement the general streamability rules; the rules used to determine the posture and sweep of any expression except when more specific rules are defined for that class of expression

Parameters:

target - the expression whose streamability is being analyzed (used only for diagnosics)

operands - the operands of the expression being evaluated

allowExtensions - true if Saxon streamability extensions are allowed

contextInfo - information about the static context item type and posture

reasons - (optionally null) an array to which explanations of non-streamability should be appended

Returns:

the posture and sweep of the expression

isChildlessNodeKind

public static boolean isChildlessNodeKind(ItemType type)

Ask whether an ItemType only allows nodes that cannot have children

Parameters:

type - the item type

Returns:

true if the item type only allows nodes that cannot have children