Class ForEach
- All Implemented Interfaces:
ContextOriginator
,ContextSwitchingExpression
,ExportAgent
,Locatable
,IdentityComparable
,Traceable
- Direct Known Subclasses:
MultithreadedForEach
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Nested Class Summary
Nested Classes -
Field Summary
FieldsModifier and TypeFieldDescriptionprotected boolean
protected Operand
protected boolean
protected Operand
protected Operand
protected Operand
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
ConstructorsConstructorDescriptionForEach
(Expression select, Expression action) Create an xsl:for-each instructionForEach
(Expression select, Expression action, boolean containsTailCall, Expression threads) Create an xsl:for-each instruction -
Method Summary
Modifier and TypeMethodDescriptionaddToPathMap
(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) Add a representation of this expression to a PathMap.boolean
Ask whether it is guaranteed that every item in the result of this instruction is a newly created node.void
Check to ensure that this expression does not contain any inappropriate updating subexpressions.void
checkPermittedContents
(SchemaType parentType, boolean whole) Check that any elements and attributes constructed or returned by this expression are acceptable in the content model of a given complex type.protected int
Get the static properties of this expression (other than its type).copy
(RebindingMap rebindings) Copy an expression.protected void
void
Diagnostic print of expression structure.Get the action expression (in XSLT, the body of the xsl:for-each instructionGet the subexpression that is evaluated in the new contextMake an elaborator for this expressionGet a name identifying the kind of expression, in terms meaningful to a user.int
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().int
Get the name of this instruction for diagnostic and tracing purposesfinal ItemType
Determine the data type of the items returned by this expressionGet the number of threads requestedGet the select expressionGet the select expressiongetStaticUType
(UType contextItemType) Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.Get the (partial) name of a class that supports streaming of this kind of expressionGet the expression used to determine how many threads to use when multi-threadingboolean
Ask whether this expression contains a call (on call-template or apply-templates) that is treated as a tail call because the select expression is known to be a singletonboolean
Ask whether this expression is an instruction.boolean
Determine whether this is an updating expression as defined in the XQuery update specificationiterate
(XPathContext context) Return an Iterator to iterate over the values of the sequence.protected NodeInfo
makeSeparator
(XPathContext context) final boolean
Determine whether this instruction creates new nodes.operands()
Get the operands of this expressionoptimize
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform optimisation of an expression and its subexpressions.void
setAction
(Expression action) Set the action expression (in XSLT, the body of the xsl:for-each instruction)void
setActionExpression
(Expression action) Set the action expressionvoid
setContainsTailCall
(boolean tc) Set whether this expression contains a call (on call-template or apply-templates) that is treated as a tail call because the select expression is known to be a singletonvoid
setInstruction
(boolean inst) Say whether this ForEach expression originates as an XSLT instructionvoid
setSelect
(Expression select) Set the select expressionvoid
setSelectExpression
(Expression select) Set the select expressionvoid
setSeparatorExpression
(Expression separator) Set the separator expression (Saxon extension)void
setThreads
(Expression threads) Set the expression used to determine how many threads to use when multi-threadingProduce a short string identifying the expression for use in error messagestoString()
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.typeCheck
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform type checking of an expression and its subexpressions.unordered
(boolean retainAllNodes, boolean forStreaming) Replace this expression by a simpler expression that delivers the results without regard to order.Methods inherited from class net.sf.saxon.expr.instruct.Instruction
assembleParams, assembleTunnelParams, computeCardinality, dynamicError, evaluateAsString, evaluateItem, getNetCost, getSourceLocator, isXSLT, process, someOperandCreatesNewNodes
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, computeDependencies, computeHashCode, computeStaticProperties, dispatchTailCall, dynamicError, effectiveBooleanValue, equals, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isVacuousExpression, makeElaborator, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, toPattern, typeCheckChildren, typeError, verifyParentPointers, withLocation
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Field Details
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containsTailCall
protected boolean containsTailCall -
selectOp
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actionOp
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separatorOp
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threadsOp
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_isInstruction
protected boolean _isInstruction
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Constructor Details
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ForEach
Create an xsl:for-each instruction- Parameters:
select
- the select expressionaction
- the body of the xsl:for-each loop
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ForEach
Create an xsl:for-each instruction- Parameters:
select
- the select expressionaction
- the body of the xsl:for-each loopcontainsTailCall
- true if the body of the loop contains a tail call on the containing functionthreads
- if >1 causes multithreaded execution (Saxon-EE only)
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Method Details
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setSeparatorExpression
Set the separator expression (Saxon extension)- Parameters:
separator
- the separator expression
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getSeparatorExpression
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setInstruction
public void setInstruction(boolean inst) Say whether this ForEach expression originates as an XSLT instruction- Parameters:
inst
- true if this is an xsl:for-each instruction; false if it is the XPath "!" operator
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isInstruction
public boolean isInstruction()Ask whether this expression is an instruction. In XSLT streamability analysis this is used to distinguish constructs corresponding to XSLT instructions from other constructs.- Overrides:
isInstruction
in classInstruction
- Returns:
- true if this construct originates as an XSLT instruction
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setContainsTailCall
public void setContainsTailCall(boolean tc) Set whether this expression contains a call (on call-template or apply-templates) that is treated as a tail call because the select expression is known to be a singleton- Parameters:
tc
- true if the action expression is to be treated as a tail call
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isContainsTailCall
public boolean isContainsTailCall()Ask whether this expression contains a call (on call-template or apply-templates) that is treated as a tail call because the select expression is known to be a singleton- Returns:
- true if the action expression is to be treated as a tail call
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getSelect
Get the select expression- Returns:
- the select expression. Note this will have been wrapped in a sort expression if sorting was requested.
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setSelect
Set the select expression- Parameters:
select
- the select expression of the for-each
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getAction
Get the action expression (in XSLT, the body of the xsl:for-each instruction- Returns:
- the action expression
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setAction
Set the action expression (in XSLT, the body of the xsl:for-each instruction)- Parameters:
action
- the action expression
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getThreads
Get the expression used to determine how many threads to use when multi-threading- Returns:
- the saxon:threads expression if present, or null otherwise
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setThreads
Set the expression used to determine how many threads to use when multi-threading- Parameters:
threads
- the saxon:threads expression if present, or null otherwise
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operands
Get the operands of this expression- Specified by:
operands
in classInstruction
- Returns:
- the operands
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getInstructionNameCode
public int getInstructionNameCode()Get the name of this instruction for diagnostic and tracing purposes- Overrides:
getInstructionNameCode
in classInstruction
- Returns:
- the code for name xsl:for-each
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getSelectExpression
Get the select expression- Specified by:
getSelectExpression
in interfaceContextSwitchingExpression
- Returns:
- the select expression. Note this will have been wrapped in a sort expression if sorting was requested.
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setSelectExpression
Set the select expression- Parameters:
select
- the select expression
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setActionExpression
Set the action expression- Parameters:
action
- the select expression
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getActionExpression
Get the subexpression that is evaluated in the new context- Specified by:
getActionExpression
in interfaceContextSwitchingExpression
- Returns:
- the subexpression evaluated in the context set by the controlling expression
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getNumberOfThreadsExpression
Get the number of threads requested- Returns:
- the value of the saxon:threads attribute
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getItemType
Determine the data type of the items returned by this expression- Overrides:
getItemType
in classInstruction
- Returns:
- the data type
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getStaticUType
Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.- Overrides:
getStaticUType
in classExpression
- Parameters:
contextItemType
- static type of the context item- Returns:
- the static item type of the expression according to the XSLT 3.0 defined rules
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mayCreateNewNodes
public final boolean mayCreateNewNodes()Determine whether this instruction creates new nodes. This implementation returns true if the "action" creates new nodes. (Nodes created by the condition can't contribute to the result).- Overrides:
mayCreateNewNodes
in classInstruction
- Returns:
- true if the instruction creates new nodes under some input conditions (or if it can't be proved that it doesn't)
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Description copied from class:Expression
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.
- Overrides:
typeCheck
in classExpression
- Parameters:
visitor
- an expression visitorcontextInfo
- Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.- 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)
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optimize
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Description copied from class:Expression
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 classExpression
- Parameters:
visitor
- an expression visitorcontextInfo
- 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)
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unordered
Replace this expression by a simpler expression that delivers the results without regard to order.- Overrides:
unordered
in classExpression
- Parameters:
retainAllNodes
- set to true if the result must contain exactly the same nodes as the original; set to false if the result can eliminate (or introduce) duplicates.forStreaming
- set to true if optimizing for streaming- Returns:
- an expression that delivers the same nodes in a more convenient order
- Throws:
XPathException
- if the rewrite fails
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addToPathMap
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
- Overrides:
addToPathMap
in classExpression
- Parameters:
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the set of nodes in the path map that are affected- Returns:
- the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Parameters:
rebindings
- variables that need to be re-bound- Returns:
- the copy of the original expression
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computeSpecialProperties
protected 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:
computeSpecialProperties
in classInstruction
- Returns:
- a set of flags indicating static properties of this expression
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alwaysCreatesNewNodes
public boolean alwaysCreatesNewNodes()Description copied from class:Instruction
Ask whether it is guaranteed that every item in the result of this instruction is a newly created node.- Overrides:
alwaysCreatesNewNodes
in classInstruction
- Returns:
- true if result of the instruction is always either an empty sequence or a sequence consisting entirely of newly created nodes
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isUpdatingExpression
public boolean isUpdatingExpression()Determine whether this is an updating expression as defined in the XQuery update specification- Overrides:
isUpdatingExpression
in classExpression
- Returns:
- true if this is an updating expression
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checkForUpdatingSubexpressions
Check to ensure that this expression does not contain any inappropriate updating subexpressions. This check is overridden for those expressions that permit updating subexpressions.- Overrides:
checkForUpdatingSubexpressions
in classExpression
- Throws:
XPathException
- if the expression has a non-permitted updating subexpression
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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 provided. This implementation provides both iterate() and process() methods natively.- Overrides:
getImplementationMethod
in classInstruction
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
orExpression.EVALUATE_METHOD
orExpression.PROCESS_METHOD
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checkPermittedContents
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 classExpression
- Parameters:
parentType
- the "given complex type": the method is checking that the nodes returned by this expression are acceptable members of the content model of this typewhole
- if true, we want to check that the value of this expression satisfies the content model as a whole; if false we want to check that the value of the expression is acceptable as one part of the content- Throws:
XPathException
- if the value delivered by this expression cannot be part of the content model of the given type
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makeSeparator
- Throws:
XPathException
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iterate
Return an Iterator to iterate over the values of the sequence.- Overrides:
iterate
in classInstruction
- Parameters:
context
- supplies the context for evaluation- Returns:
- a SequenceIterator that can be used to iterate over the result of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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export
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
export
in interfaceExportAgent
- Specified by:
export
in 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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explainThreads
- Throws:
XPathException
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toString
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.
For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression
- Overrides:
toString
in classExpression
- Returns:
- a representation of the expression as a string
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toShortString
Description copied from class:Expression
Produce a short string identifying the expression for use in error messages- Overrides:
toShortString
in classExpression
- Returns:
- a short string, sufficient to identify the expression
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getExpressionName
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionName
in classInstruction
- Returns:
- a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.
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getStreamerName
Get the (partial) name of a class that supports streaming of this kind of expression- Overrides:
getStreamerName
in 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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getElaborator
Make an elaborator for this expression- Overrides:
getElaborator
in classExpression
- Returns:
- a suitable elaborator
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