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Summary: Nested | Field | Method | Constr | Detail: Nested | Field | Method | Constr |
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.instruct.Instruction
net.sf.saxon.instruct.ParentNodeConstructor
net.sf.saxon.instruct.ElementCreator
net.sf.saxon.instruct.ComputedElement
public class ComputedElement
extends ElementCreator
FixedElement
Field Summary |
Fields inherited from class net.sf.saxon.instruct.ElementCreator | |
inheritNamespaces , preservingTypes |
Fields inherited from class net.sf.saxon.instruct.ParentNodeConstructor | |
content |
Fields inherited from class net.sf.saxon.expr.Expression | |
EVALUATE_METHOD , ITERATE_METHOD , PROCESS_METHOD , locationId , staticProperties |
Constructor Summary | |
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Method Summary | |
void |
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Expression |
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void |
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int |
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ItemType |
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int |
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Expression | |
Expression | |
NamespaceResolver | |
String |
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Iterator |
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Expression |
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protected void |
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protected void |
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boolean |
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Expression |
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Expression |
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Methods inherited from class net.sf.saxon.instruct.ElementCreator | |
checkContentSequence , computeSpecialProperties , evaluateItem , getActiveNamespaces , getImplementationMethod , getItemType , getNameCode , getNewBaseURI , isInheritNamespaces , isPreservingTypes , iterateEvents , outputNamespaceNodes , processLeavingTail , setValidationMode , suppressValidation |
Methods inherited from class net.sf.saxon.instruct.ParentNodeConstructor | |
addToPathMap , checkContentSequence , computeCardinality , createsNewNodes , getBaseURI , getCardinality , getContentExpression , getSchemaType , getValidationMode , isLazyConstruction , isNamespaceSensitive , iterateSubExpressions , optimize , promoteInst , replaceSubExpression , setBaseURI , setContentExpression , setLazyConstruction , setSchemaType , setValidationMode , simplify , typeCheck |
Methods inherited from class net.sf.saxon.instruct.Instruction | |
assembleParams , assembleTunnelParams , computeCardinality , computeSpecialProperties , createsNewNodes , dynamicError , evaluateAsString , evaluateItem , getImplementationMethod , getInstructionInfo , getInstructionNameCode , getItemType , getSourceLocator , isXSLT , iterate , process , processLeavingTail , promote , promoteInst , simplify |
public ComputedElement(Expression elementName, Expression namespace, NamespaceResolver nsContext, String defaultNamespace, SchemaType schemaType, int validation, boolean inheritNamespaces, boolean allowQName)
Create an instruction that creates a new element node
- Parameters:
elementName
- Expression that evaluates to produce the name of the element node as a lexical QNamenamespace
- Expression that evaluates to produce the namespace URI of the element node. Set to null if the namespace is to be deduced from the prefix of the elementName.nsContext
- Saved copy of the static namespace context for the instruction. Can be set to null if namespace is supplied.schemaType
- The required schema type for the contentallowQName
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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 interface Expression
public Expression copy()
Copy an expression. This makes a deep copy.
- Overrides:
- copy in interface Expression
- Returns:
- the copy of the original expression
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
- Overrides:
- explain in interface Expression
public int getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes
- Overrides:
- getInstructionNameCode in interface Instruction
public ItemType getItemType(TypeHierarchy th)
Get the item type of the value returned by this instruction
- Overrides:
- getItemType in interface ElementCreator
- Parameters:
th
- the type hierarchy cache
- Returns:
- the item type
public int getNameCode(XPathContext context) throws XPathException
Callback from the superclass ElementCreator to get the nameCode for the element name
- Overrides:
- getNameCode in interface ElementCreator
- Parameters:
context
- The evaluation context (not used)
- Returns:
- the name code for the element name
public String getNewBaseURI(XPathContext context)
- Overrides:
- getNewBaseURI in interface ElementCreator
public Iterator iterateSubExpressions()
Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
- Overrides:
- iterateSubExpressions in interface ParentNodeConstructor
- Returns:
- an iterator containing the sub-expressions of this expression
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization. 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.
- Overrides:
- optimize in interface ParentNodeConstructor
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
protected void outputNamespaceNodes(XPathContext context, Receiver out) throws XPathException
Callback to output namespace nodes for the new element.
- Overrides:
- outputNamespaceNodes in interface ElementCreator
- Parameters:
context
- The execution contextout
- the Receiver where the namespace nodes are to be written
- Throws:
XPathException
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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 interface ParentNodeConstructor
- 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
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression
- Overrides:
- replaceSubExpression in interface ParentNodeConstructor
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression
- Returns:
- true if the original subexpression is found
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
- Overrides:
- simplify in interface ParentNodeConstructor
- Parameters:
visitor
- an expression visitor
- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Perform type checking of an expression and its subexpressions. This is the second phase of static optimization. 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 parent pointer and 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.
- Overrides:
- typeCheck in interface ParentNodeConstructor
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)