net.sf.saxon.instruct
Class Attribute

java.lang.Object
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  +--net.sf.saxon.instruct.Instruction
        |
        +--net.sf.saxon.instruct.ExprInstruction
              |
              +--net.sf.saxon.instruct.SimpleNodeConstructor
                    |
                    +--net.sf.saxon.instruct.Attribute
All Implemented Interfaces:
Expression, Instr, Locatable, java.io.Serializable, javax.xml.transform.SourceLocator

public final class Attribute
extends SimpleNodeConstructor

An instruction derived from an xsl:attribute element in stylesheet, or from an attribute constructor in XQuery

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.instruct.SimpleNodeConstructor
select, separator
 
Fields inherited from class net.sf.saxon.instruct.Instruction
children
 
Constructor Summary
Attribute(Expression attributeName, Expression namespace, NamespaceResolver nsContext, int validationAction, SimpleType schemaType, int annotation)
          Construct an Attribute instruction
 
Method Summary
 void display(int level, NamePool pool)
          Display this instruction as an expression, for diagnostics
protected  int evaluateNameCode(XPathContext context)
           
 int getCardinality()
          Determine the static cardinality of the expression.
 int getDependencies()
          Determine which aspects of the context the expression depends on.
 java.lang.String getInstructionName()
          Get the name of this instruction
 ItemType getItemType()
          Determine the data type of the expression, if possible.
 void getXPathExpressions(java.util.List list)
          Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)
 TailCall processLeavingTail(XPathContext context)
          Process this instruction
 void promoteInst(PromotionOffer offer)
          Offer promotion for subexpressions.
 void setRejectDuplicates()
          Indicate that two attributes with the same name are not acceptable.
 Expression simplify()
          Simplify an expression.
 void typeCheck(StaticContext env)
           
 
Methods inherited from class net.sf.saxon.instruct.SimpleNodeConstructor
analyze, evaluateItem, expandChildren, setSelect, setSeparator
 
Methods inherited from class net.sf.saxon.instruct.ExprInstruction
effectiveBooleanValue, evaluateAsString, getSpecialProperties, getSubExpressions, iterate, promote
 
Methods inherited from class net.sf.saxon.instruct.Instruction
assembleParams, assembleTunnelParams, displayChildren, dynamicError, dynamicError, getChildren, getColumnNumber, getExecutable, getInstructionNamespace, getLineNumber, getPublicId, getSourceLocator, getSystemId, process, processChildren, processChildrenLeavingTail, recoverableError, setChildren, setExecutable, setSourceLocation
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Attribute

public Attribute(Expression attributeName,
                 Expression namespace,
                 NamespaceResolver nsContext,
                 int validationAction,
                 SimpleType schemaType,
                 int annotation)
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
annotation - Integer code identifying the type named in the type attribute of the instruction - zero if the attribute was not present
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)


getInstructionName

public java.lang.String getInstructionName()
Get the name of this instruction

Specified by:
getInstructionName in class Instruction

getItemType

public ItemType getItemType()
Description copied from interface: Expression
Determine the data type of the expression, if possible. All expression return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.

This method should always return a result, though it may be the best approximation that is available at the time.

Specified by:
getItemType in interface Expression
Overrides:
getItemType in class Instruction
Returns:
a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

getCardinality

public int getCardinality()
Description copied from interface: 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.

This method should always return a result, though it may be the best approximation that is available at the time.

Specified by:
getCardinality in interface Expression
Overrides:
getCardinality in class Instruction
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).

simplify

public Expression simplify()
                    throws XPathException
Description copied from class: ExprInstruction
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.

Specified by:
simplify in interface Expression
Overrides:
simplify in class ExprInstruction
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

typeCheck

public void typeCheck(StaticContext env)
               throws XPathException
Specified by:
typeCheck in class SimpleNodeConstructor
XPathException

getDependencies

public int getDependencies()
Description copied from class: ExprInstruction
Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as StaticProperty.DEPENDS_ON_CONTEXT_ITEM and StaticProperty.DEPENDS_ON_CURRENT_ITEM. The default implementation combines the intrinsic dependencies of this expression with the dependencies of the subexpressions, computed recursively. This is overridden for expressions such as FilterExpression where a subexpression's dependencies are not necessarily inherited by the parent expression.

Specified by:
getDependencies in interface Expression
Overrides:
getDependencies in class ExprInstruction
Returns:
a set of bit-significant flags identifying the dependencies of the expression

getXPathExpressions

public void getXPathExpressions(java.util.List list)
Description copied from class: ExprInstruction
Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)

Overrides:
getXPathExpressions in class SimpleNodeConstructor
Parameters:
list - A list to be populated with the list of XPath expressions

promoteInst

public void promoteInst(PromotionOffer offer)
                 throws XPathException
Offer promotion for subexpressions. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.

Overrides:
promoteInst in class SimpleNodeConstructor
Parameters:
offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
Throws:
XPathException - if any error is detected

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws javax.xml.transform.TransformerException
Process this instruction

Specified by:
processLeavingTail in interface Instr
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
javax.xml.transform.TransformerException

evaluateNameCode

protected int evaluateNameCode(XPathContext context)
                        throws XPathException,
                               javax.xml.transform.TransformerException
Overrides:
evaluateNameCode in class SimpleNodeConstructor
XPathException
javax.xml.transform.TransformerException

display

public void display(int level,
                    NamePool pool)
Display this instruction as an expression, for diagnostics

Specified by:
display in interface Expression
Overrides:
display in class SimpleNodeConstructor
Parameters:
level - indentation level for this expression