Class DocumentInstr
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.instruct.Instruction
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- net.sf.saxon.instruct.ParentNodeConstructor
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- net.sf.saxon.instruct.DocumentInstr
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,EvaluableItem
,SequenceIterable
,TailCallReturner
,InstructionInfo
,org.xml.sax.Locator
public class DocumentInstr extends ParentNodeConstructor
An instruction to create a document node. This corresponds to the xsl:document-node instruction in XSLT. It is also used to support the document node constructor expression in XQuery, and is generated implicitly within an xsl:variable that constructs a temporary tree.Conceptually it represents an XSLT instruction xsl:document-node, with no attributes, whose content is a complex content constructor for the children of the document node.
- See Also:
- Serialized Form
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Field Summary
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Fields inherited from class net.sf.saxon.instruct.ParentNodeConstructor
content
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Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors Constructor Description DocumentInstr(boolean textOnly, java.lang.String constantText, java.lang.String baseURI)
Create a document constructor instruction
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description protected void
checkContentSequence(StaticContext env)
Check statically that the sequence of child instructions doesn't violate any obvious constraints on the content of the nodeprotected static void
checkContentSequence(StaticContext env, Expression content, int validation, SchemaType type)
Expression
copy()
Copy an expression.Item
evaluateItem(XPathContext context)
Evaluate as an expression.void
explain(ExpressionPresenter out)
Diagnostic print of expression structure.int
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().int
getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")ItemType
getItemType(TypeHierarchy th)
Get the item typeExpression
getStringValueExpression(StaticContext env)
In the case of a text-only instruction (xsl:variable containing a text node or one or more xsl:value-of instructions), return an expression that evaluates to the textual content as an instance of xs:untypedAtomicboolean
isTextOnly()
Determine whether this is a "text only" document: essentially, an XSLT xsl:variable that contains a single text node or xsl:value-of instruction.EventIterator
iterateEvents(XPathContext context)
Deliver the result of the expression as a sequence of events.TailCall
processLeavingTail(XPathContext context)
ProcessLeavingTail: called to do the real work of this instruction.Expression
simplify(ExpressionVisitor visitor)
Simplify an expression.-
Methods inherited from class net.sf.saxon.instruct.ParentNodeConstructor
addToPathMap, computeCardinality, createsNewNodes, getBaseURI, getCardinality, getContentExpression, getSchemaType, getValidationMode, isLazyConstruction, isNamespaceSensitive, iterateSubExpressions, optimize, promoteInst, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType, setValidationMode, typeCheck
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Methods inherited from class net.sf.saxon.instruct.Instruction
assembleParams, assembleTunnelParams, computeSpecialProperties, dynamicError, evaluateAsString, getConstructType, getSourceLocator, isXSLT, iterate, process, promote
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Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, findParentOf, getColumnNumber, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError
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Constructor Detail
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DocumentInstr
public DocumentInstr(boolean textOnly, java.lang.String constantText, java.lang.String baseURI)
Create a document constructor instruction- Parameters:
textOnly
- true if the content contains text nodes onlyconstantText
- if the content contains text nodes only and the text is known at compile time, supplies the textual contentbaseURI
- the base URI of the instruction
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Method Detail
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getImplementationMethod
public int getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is prefered. For instructions this is the process() method.- Overrides:
getImplementationMethod
in classInstruction
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
orExpression.EVALUATE_METHOD
orExpression.PROCESS_METHOD
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isTextOnly
public boolean isTextOnly()
Determine whether this is a "text only" document: essentially, an XSLT xsl:variable that contains a single text node or xsl:value-of instruction.- Returns:
- true if this is a text-only document
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simplify
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 classParentNodeConstructor
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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checkContentSequence
protected void checkContentSequence(StaticContext env) throws XPathException
Check statically that the sequence of child instructions doesn't violate any obvious constraints on the content of the node- Specified by:
checkContentSequence
in classParentNodeConstructor
- Parameters:
env
- the static context- Throws:
XPathException
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checkContentSequence
protected static void checkContentSequence(StaticContext env, Expression content, int validation, SchemaType type) throws XPathException
- Throws:
XPathException
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getStringValueExpression
public Expression getStringValueExpression(StaticContext env)
In the case of a text-only instruction (xsl:variable containing a text node or one or more xsl:value-of instructions), return an expression that evaluates to the textual content as an instance of xs:untypedAtomic- Parameters:
env
- the static evaluation context- Returns:
- an expression that evaluates to the textual content
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copy
public Expression copy()
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
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getItemType
public ItemType getItemType(TypeHierarchy th)
Get the item type- Overrides:
getItemType
in classInstruction
- Parameters:
th
- The TypeHierarchy- Returns:
- the in
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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 interfaceTailCallReturner
- Specified by:
processLeavingTail
in classInstruction
- 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.
- Throws:
XPathException
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evaluateItem
public Item evaluateItem(XPathContext context) throws XPathException
Evaluate as an expression.- Specified by:
evaluateItem
in interfaceEvaluableItem
- Overrides:
evaluateItem
in classInstruction
- 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
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iterateEvents
public EventIterator iterateEvents(XPathContext context) throws XPathException
Description copied from class:Expression
Deliver the result of the expression as a sequence of events.The events (of class
PullEvent
) are either complete items, or one of startElement, endElement, startDocument, or endDocument, known as semi-nodes. The stream of events may also include a nested EventIterator. If a start-end pair exists in the sequence, then the events between this pair represent the content of the document or element. The content sequence will have been processed to the extent that any attribute and namespace nodes in the content sequence will have been merged into the startElement event. Namespace fixup will have been performed: that is, unique prefixes will have been allocated to element and attribute nodes, and all namespaces will be declared by means of a namespace node in the startElement event or in an outer startElement forming part of the sequence. However, duplicate namespaces may appear in the sequence.The content of an element or document may include adjacent or zero-length text nodes, atomic values, and nodes represented as nodes rather than broken down into events.
- Overrides:
iterateEvents
in classExpression
- Parameters:
context
- The dynamic evaluation context- Returns:
- the result of the expression as an iterator over a sequence of PullEvent objects
- Throws:
XPathException
- if a dynamic error occurs during expression evaluation
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getInstructionNameCode
public int getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")- Overrides:
getInstructionNameCode
in classInstruction
- Returns:
- a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace
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explain
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
explain
in classExpression
- Parameters:
out
- the expression presenter used to display the structure
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