net.sf.saxon.instruct
Class ValueOf
java.lang.Object
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+--net.sf.saxon.expr.ComputedExpression
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+--net.sf.saxon.instruct.Instruction
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+--net.sf.saxon.instruct.InstructionWithChildren
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+--net.sf.saxon.instruct.SimpleNodeConstructor
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+--net.sf.saxon.instruct.ValueOf
- All Implemented Interfaces:
- Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator
- public final class ValueOf
- extends SimpleNodeConstructor
An xsl:value-of element in the stylesheet.
The xsl:value-of element takes attributes:
- a mandatory attribute select="expression".
This must be a valid String expression
- an optional disable-output-escaping attribute, value "yes" or "no"
- an optional separator attribute. This is handled at compile-time: if the separator attribute
is present, the select expression passed in here will be a call to the string-join() function.
- See Also:
- Serialized Form
Methods inherited from class net.sf.saxon.instruct.Instruction |
appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getImplementationMethod, getInstructionInfo, getSourceLocator, process, promote |
Methods inherited from class net.sf.saxon.expr.ComputedExpression |
adoptChildExpression, computeDependencies, computeStaticProperties, dynamicError, dynamicError, getColumnNumber, getConstructType, getDependencies, getExecutable, getIntrinsicDependencies, getLineNumber, getLocationId, getParentExpression, getPublicId, getSpecialProperties, getSystemId, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, typeError |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface javax.xml.transform.SourceLocator |
getColumnNumber, getLineNumber, getPublicId, getSystemId |
ValueOf
public ValueOf(Expression select,
boolean disable)
getInstructionNameCode
public int getInstructionNameCode()
- Get the name of this instruction for diagnostic and tracing purposes
- Overrides:
getInstructionNameCode
in class Instruction
promoteInst
protected 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
getItemType
public ItemType getItemType()
- Description copied from class:
Instruction
- Get the item type of the items returned by evaluating this instruction
- Specified by:
getItemType
in interface Expression
- Overrides:
getItemType
in class Instruction
- Returns:
- the static item type of the instruction
getCardinality
public int getCardinality()
- Description copied from class:
ComputedExpression
- 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.
- Specified by:
getCardinality
in interface Expression
- Overrides:
getCardinality
in class ComputedExpression
- 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).
typeCheck
public void typeCheck(StaticContext env,
ItemType contextItemType)
- Specified by:
typeCheck
in class SimpleNodeConstructor
processLeavingTail
public TailCall processLeavingTail(XPathContext context)
throws XPathException
- Description copied from class:
Instruction
- ProcessLeavingTail: called to do the real work of this instruction. This method
must be implemented in each subclass. The results of the instruction are written
to the current Receiver, which can be obtained via the Controller.
- Specified by:
processLeavingTail
in class Instruction
- Parameters:
context
- The dynamic context of the transformation, giving access to the current node,
the current variables, etc.
- Returns:
- null if the instruction has completed execution; or a TailCall indicating
a function call or template call that is delegated to the caller, to be made after the stack has
been unwound so as to save stack space.
XPathException
evaluateItem
public Item evaluateItem(XPathContext context)
throws XPathException
- Description copied from class:
SimpleNodeConstructor
- Evaluate as an expression. We rely on the fact that when these instructions
are generated by XQuery, there will always be a valueExpression to evaluate
the content
- Specified by:
evaluateItem
in interface Expression
- Overrides:
evaluateItem
in class SimpleNodeConstructor
- 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
display
public void display(int level,
NamePool pool,
java.io.PrintStream out)
- 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 expressionpool
- NamePool used to expand any names appearing in the expressionout
- Output destination