Package net.sf.saxon.expr.instruct
Class DocumentInstr
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.instruct.Instruction
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- net.sf.saxon.expr.instruct.ParentNodeConstructor
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- net.sf.saxon.expr.instruct.DocumentInstr
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- All Implemented Interfaces:
ExportAgent,InstructionWithComplexContent,TailCallReturner,ValidatingInstruction,Locatable,IdentityComparable,Traceable
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.
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Field Summary
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Fields inherited from class net.sf.saxon.expr.instruct.ParentNodeConstructor
contentOp, preservingTypes
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Fields inherited from class net.sf.saxon.expr.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD
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Constructor Summary
Constructors Constructor Description DocumentInstr(boolean textOnly, java.lang.String constantText)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 voidcheckContentSequence(StaticContext env)Check statically that the sequence of child instructions doesn't violate any obvious constraints on the content of the nodeprotected static voidcheckContentSequence(StaticContext env, Operand content, ParseOptions validationOptions)intcomputeSpecialProperties()Get the static properties of this expression (other than its type).Expressioncopy(RebindingMap rebindings)Copy an expression.NodeInfoevaluateItem(XPathContext context)Evaluate as an item.voidexport(ExpressionPresenter out)Diagnostic print of expression structure.java.lang.CharSequencegetConstantText()For a text-only instruction, determine if the text value is fixed and if so return it; otherwise return nullintgetImplementationMethod()An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().intgetInstructionNameCode()Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")ItemTypegetItemType()Get the item typejava.lang.StringgetStreamerName()Get the (partial) name of a class that supports streaming of this kind of expressionExpressiongetStringValueExpression()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:untypedAtomicbooleanisTextOnly()Determine whether this is a "text only" document: essentially, an XSLT xsl:variable that contains a single text node or xsl:value-of instruction.java.lang.Iterable<Operand>operands()Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.TailCallprocessLeavingTail(Outputter output, XPathContext context)ProcessLeavingTail: called to do the real work of this instruction.-
Methods inherited from class net.sf.saxon.expr.instruct.ParentNodeConstructor
addToPathMap, allowExtractingCommonSubexpressions, alwaysCreatesNewNodes, computeCardinality, getCardinality, getContentExpression, getContentOperand, getSchemaType, getValidationAction, getValidationOptions, isLocal, isPreservingTypes, mayCreateNewNodes, optimize, setContentExpression, setNoNeedToStrip, setValidationAction, typeCheck
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Methods inherited from class net.sf.saxon.expr.instruct.Instruction
assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getExpressionName, getNetCost, getSourceLocator, isInstruction, isXSLT, iterate, process, someOperandCreatesNewNodes
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Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeStaticProperties, dynamicError, effectiveBooleanValue, equals, evaluatePendingUpdates, explain, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toShortString, toString, typeCheckChildren, typeError, unordered, verifyParentPointers
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Constructor Detail
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DocumentInstr
public DocumentInstr(boolean textOnly, java.lang.String constantText)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 content
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Method Detail
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operands
public java.lang.Iterable<Operand> operands()
Description copied from class:ExpressionGet the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.
- Specified by:
operandsin classInstruction- Returns:
- an iterator containing the sub-expressions of this expression
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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:
getImplementationMethodin classInstruction- Returns:
- the implementation method, for example
Expression.ITERATE_METHODorExpression.EVALUATE_METHODorExpression.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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getConstantText
public java.lang.CharSequence getConstantText()
For a text-only instruction, determine if the text value is fixed and if so return it; otherwise return null- Returns:
- the fixed text value if appropriate; otherwise null
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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:
checkContentSequencein classParentNodeConstructor- Parameters:
env- the static context- Throws:
XPathException
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checkContentSequence
protected static void checkContentSequence(StaticContext env, Operand content, ParseOptions validationOptions) throws XPathException
- Throws:
XPathException
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computeSpecialProperties
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.- Overrides:
computeSpecialPropertiesin classInstruction- Returns:
- a set of flags indicating static properties of this expression
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getStringValueExpression
public Expression getStringValueExpression()
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- Returns:
- an expression that evaluates to the textual content
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copy
public Expression copy(RebindingMap rebindings)
Copy an expression. This makes a deep copy.- Specified by:
copyin classExpression- Parameters:
rebindings-- Returns:
- the copy of the original expression
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getItemType
public ItemType getItemType()
Get the item type- Overrides:
getItemTypein classInstruction- Returns:
- the in
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processLeavingTail
public TailCall processLeavingTail(Outputter output, XPathContext context) throws XPathException
Description copied from class:InstructionProcessLeavingTail: 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:
processLeavingTailin interfaceTailCallReturner- Specified by:
processLeavingTailin classInstruction- Parameters:
output- the destination for the resultcontext- 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- if a dynamic error occurs during the evaluation of the instruction
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evaluateItem
public NodeInfo evaluateItem(XPathContext context) throws XPathException
Evaluate as an item.- Overrides:
evaluateItemin 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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getInstructionNameCode
public int getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")- Overrides:
getInstructionNameCodein classInstruction- Returns:
- a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace
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export
public void export(ExpressionPresenter out) throws XPathException
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
exportin interfaceExportAgent- Specified by:
exportin classExpression- Parameters:
out- the expression presenter used to display the structure- Throws:
XPathException- if the export fails, for example if an expression is found that won't work in the target environment.
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getStreamerName
public java.lang.String getStreamerName()
Get the (partial) name of a class that supports streaming of this kind of expression- Overrides:
getStreamerNamein classExpression- Returns:
- the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class
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