net.sf.saxon.instruct
Class ComputedAttribute

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.instruct.Instruction
          net.sf.saxon.instruct.SimpleNodeConstructor
              net.sf.saxon.instruct.ComputedAttribute

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfoProvider

public final class ComputedAttribute
extends SimpleNodeConstructor

An instruction derived from an xsl:attribute element in stylesheet, or from an attribute constructor in XQuery, in cases where the attribute name is not known statically

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

ComputedAttribute(Expression attributeName, Expression namespace, NamespaceResolver nsContext, int validationAction, SimpleType schemaType, int annotation, boolean allowNameAsQName)
Construct an Attribute instruction

Method Summary

void	checkPermittedContents(SchemaType parentType, StaticContext env, boolean whole) Check that any elements and attributes constructed or returned by this expression are acceptable in the content model of a given complex type.
int	computeSpecialProperties() Get the static properties of this expression (other than its type).
void	display(int level, PrintStream out, Configuration config) Display this instruction as an expression, for diagnostics
int	evaluateNameCode(XPathContext context) Determine the name to be used for the attribute, as an integer name code
int	getCardinality() Determine the static cardinality of the expression.
int	getInstructionNameCode() Get the name of this instruction
ItemType	getItemType(TypeHierarchy th) Get the item type of the items returned by evaluating this instruction
Expression	getNameExpression()
Expression	getNamespaceExpression()
NamespaceResolver	getNamespaceResolver()
Iterator	iterateSubExpressions() Get the subexpressions of this expression
void	localTypeCheck(StaticContext env, ItemType contextItemType) Method to perform type-checking specific to the kind of instruction
TailCall	processLeavingTail(XPathContext context) Process this instruction
boolean	replaceSubExpression(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	setRejectDuplicates() Indicate that two attributes with the same name are not acceptable.
Expression	simplify(StaticContext env) Simplify an expression.

Methods inherited from class net.sf.saxon.instruct.SimpleNodeConstructor

computeCardinality, createsNewNodes, evaluateItem, expandChildren, getSelect, iterate, optimize, setSelect, typeCheck

Methods inherited from class net.sf.saxon.instruct.Instruction

appendItem, evaluateAsString, getImplementationMethod, getInstructionInfo, getSourceLocator, isXSLT, process, promote

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

adoptChildExpression, computeDependencies, computeStaticProperties, doPromotion, effectiveBooleanValue, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

Constructor Detail

ComputedAttribute

public ComputedAttribute(Expression attributeName,
                         Expression namespace,
                         NamespaceResolver nsContext,
                         int validationAction,
                         SimpleType schemaType,
                         int annotation,
                         boolean allowNameAsQName)

Construct an Attribute instruction

Parameters:

attributeName - An expression to calculate the attribute name

namespace - An expression to calculate the attribute namespace

nsContext - a NamespaceContext object containing the static namespace context of the stylesheet instruction

validationAction - e.g. validation=strict, lax, strip, preserve

schemaType - Type against which the attribute must be validated. This must not be a namespace-sensitive type; it is the caller's responsibility to check this.

annotation - Integer code identifying the type named in the type attribute

allowNameAsQName -

Method Detail

setRejectDuplicates

public void setRejectDuplicates()

Indicate that two attributes with the same name are not acceptable. (This option is set in XQuery, but not in XSLT)

getInstructionNameCode

public int getInstructionNameCode()

Get the name of this instruction

Overrides:

getInstructionNameCode in class Instruction

getNameExpression

public Expression getNameExpression()

getNamespaceExpression

public Expression getNamespaceExpression()

getNamespaceResolver

public NamespaceResolver getNamespaceResolver()

getItemType

public ItemType getItemType(TypeHierarchy th)

Description copied from class: Instruction

Get the item type of the items returned by evaluating this instruction

Overrides:

getItemType in class Instruction

Returns:

the static item type of the instruction

getCardinality

public int getCardinality()

Description copied from class: Expression

Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.

Overrides:

getCardinality in class Expression

Returns:

one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).

computeSpecialProperties

public int computeSpecialProperties()

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 SimpleNodeConstructor

Returns:

a set of flags indicating static properties of this expression

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

Description copied from class: Instruction

Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.

Overrides:

simplify in class SimpleNodeConstructor

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

localTypeCheck

public void localTypeCheck(StaticContext env,
                           ItemType contextItemType)
                    throws XPathException

Description copied from class: SimpleNodeConstructor

Method to perform type-checking specific to the kind of instruction

Specified by:

localTypeCheck in class SimpleNodeConstructor

Throws:

XPathException

iterateSubExpressions

public Iterator iterateSubExpressions()

Get the subexpressions of this expression

Overrides:

iterateSubExpressions in class SimpleNodeConstructor

Returns:

an iterator over the subexpressions

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)

Replace one subexpression by a replacement subexpression

Specified by:

replaceSubExpression in interface Container

Overrides:

replaceSubExpression in class SimpleNodeConstructor

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

checkPermittedContents

public void checkPermittedContents(SchemaType parentType,
                                   StaticContext env,
                                   boolean whole)
                            throws XPathException

Check that any elements and attributes constructed or returned by this expression are acceptable in the content model of a given complex type. It's always OK to say yes, since the check will be repeated at run-time. The process of checking element and attribute constructors against the content model of a complex type also registers the type of content expected of those constructors, so the static validation can continue recursively.

Overrides:

checkPermittedContents in class Expression

Throws:

XPathException

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException

Process this instruction

Specified by:

processLeavingTail in interface TailCallReturner

Specified by:

processLeavingTail in class Instruction

Parameters:

context - the dynamic context of the transformation

Returns:

a TailCall to be executed by the caller, always null for this instruction

Throws:

XPathException

evaluateNameCode

public int evaluateNameCode(XPathContext context)
                     throws XPathException

Determine the name to be used for the attribute, as an integer name code

Overrides:

evaluateNameCode in class SimpleNodeConstructor

Parameters:

context - Dynamic evaluation context

Returns:

the integer name code for the attribute name

Throws:

XPathException

display

public void display(int level,
                    PrintStream out,
                    Configuration config)

Display this instruction as an expression, for diagnostics

Overrides:

display in class SimpleNodeConstructor

Parameters:

level - indentation level for this expression

out - Output destination