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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.instruct.Instruction net.sf.saxon.expr.instruct.LocalParamSetter
public final class LocalParamSetter
The compiled form of an xsl:param element within a template in an XSLT stylesheet. An xsl:param element used as a template parameter is compiled into two objects: a LocalParam which represents the parameter definition and the Binding for the value, and a LocalParamSetter which is an Instruction to set a default value for the parameter if none has been supplied.
The xsl:param element in XSLT has mandatory attribute name and optional attribute select. It can also be specified as required="yes" or required="no".
This is used only for parameters to XSLT templates. For function calls, the caller of the function
places supplied arguments onto the callee's stackframe and the callee does not need to do anything.
Global parameters (XQuery external variables) are handled using GlobalParam
.
The LocalParam class is also used to represent parameters with the saxon:iterate instruction
Field Summary |
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Fields inherited from class net.sf.saxon.expr.Expression |
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EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD |
Constructor Summary | |
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LocalParamSetter(LocalParam binding)
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Method Summary | |
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int |
computeCardinality()
Get the cardinality of the sequence returned by evaluating this instruction |
int |
computeSpecialProperties()
Get the static properties of this expression (other than its type). |
Expression |
copy()
Copy an expression. |
boolean |
createsNewNodes()
Determine whether this instruction creates new nodes. |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
LocalParam |
getBinding()
Get the LocalParam element representing the binding for this parameter |
int |
getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes |
ItemType |
getItemType(TypeHierarchy th)
Get the item type of the items returned by evaluating this instruction |
Iterator<Expression> |
iterateSubExpressions()
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) |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
TailCall |
processLeavingTail(XPathContext context)
Process the local parameter declaration |
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression |
simplify(ExpressionVisitor visitor)
Simplify an expression. |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform type checking of an expression and its subexpressions. |
Methods inherited from class net.sf.saxon.expr.instruct.Instruction |
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assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, evaluateItem, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getIteratorFromProcessMethod, getSourceLocator, isXSLT, iterate, process, promote, promoteInst |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Methods inherited from interface javax.xml.transform.SourceLocator |
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getColumnNumber, getLineNumber, getPublicId, getSystemId |
Constructor Detail |
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public LocalParamSetter(LocalParam binding)
Method Detail |
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public LocalParam getBinding()
public ItemType getItemType(TypeHierarchy th)
getItemType
in class Instruction
th
- the type hierarchy cache
public int computeCardinality()
computeCardinality
in class Instruction
public int computeSpecialProperties()
computeSpecialProperties
in class Instruction
public boolean createsNewNodes()
createsNewNodes
in class Instruction
public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
in class Instruction
visitor
- an expression visitor
XPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.
If the implementation returns a value other than "this", then it is required to ensure that the location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
typeCheck
in class Expression
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
optimize
in class Expression
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression copy()
copy
in class Expression
public int getInstructionNameCode()
getInstructionNameCode
in class Instruction
public Iterator<Expression> iterateSubExpressions()
iterateSubExpressions
in class Expression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in class Expression
original
- the original subexpressionreplacement
- the replacement subexpression
public TailCall processLeavingTail(XPathContext context) throws XPathException
processLeavingTail
in interface TailCallReturner
processLeavingTail
in class Instruction
context
- The dynamic context of the transformation, giving access to the current node,
the current variables, etc.
XPathException
- if a dynamic error occurs during the evaluation
of the instructionpublic void explain(ExpressionPresenter out)
explain
in class Expression
out
- the expression presenter used to display the structure
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