Class Assignation
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.Assignation
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,Binding
,InstructionInfo
,org.xml.sax.Locator
- Direct Known Subclasses:
ForExpression
,LetExpression
,QuantifiedExpression
public abstract class Assignation extends Expression implements Binding
Assignation is an abstract superclass for the kinds of expression that declare range variables: for, some, and every.- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected Expression
action
(package private) int
refCount
protected SequenceType
requiredType
protected Expression
sequence
protected int
slotNumber
protected StructuredQName
variableName
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Fields inherited from class net.sf.saxon.expr.Expression
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
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Constructor Summary
Constructors Constructor Description Assignation()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addReference(boolean isLoopingReference)
Register a variable reference that refers to the variable bound in this expressionPathMap.PathMapNodeSet
addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap.void
checkForUpdatingSubexpressions()
Check to ensure that this expression does not contain any inappropriate updating subexpressions.ValueRepresentation
evaluateVariable(XPathContext context)
Get the value of the range variableBinding[]
extendBindingList(Binding[] in)
Extend an array of variable bindings to include the binding(s) defined in this expressionExpression
getAction()
Get the action expressionIntegerValue[]
getIntegerBoundsForVariable()
If the variable is bound to an integer, get the minimum and maximum possible values.int
getLocalSlotNumber()
If this is a local variable held on the local stack frame, return the corresponding slot number.int
getNominalReferenceCount()
Get the (nominal) count of the number of references to this variableStructuredQName
getObjectName()
Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc.int
getRequiredSlots()
Get the number of slots required.SequenceType
getRequiredType()
Get the declared type of the variableExpression
getSequence()
Get the "sequence" expression - the one to which the variable is boundjava.lang.String
getVariableName()
Get the display name of the range variable, for diagnostics onlyStructuredQName
getVariableQName()
Get the name of the variableboolean
hasVariableBinding(Binding binding)
boolean
isAssignable()
Test whether it is permitted to assign to the variable using the saxon:assign extension element.boolean
isGlobal()
Indicate whether the binding is local or global.boolean
isIndexedVariable()
Test whether the variable bound by this let expression should be indexableboolean
isUpdatingExpression()
Determine whether this is an updating expression as defined in the XQuery update specificationjava.util.Iterator<Expression>
iterateSubExpressions()
Get the immediate subexpressions of this expressionExpression
promote(PromotionOffer offer, Expression parent)
Promote this expression if possibleprotected Expression
promoteWhereClause(Binding positionBinding)
Promote a WHERE clause whose condition doesn't depend on the variable being bound.void
refineTypeInformation(ItemType type, int cardinality, Value constantValue, int properties, ExpressionVisitor visitor, Assignation currentExpression)
Refine the type information associated with this variable declaration.boolean
replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpressionvoid
replaceVariable(Optimizer opt, Expression seq)
Replace all references to the variable bound by this let expression, that occur within the action expression, with the given expressionvoid
setAction(Expression action)
Add the "return" or "satisfies" expression, and fix up all references to the range variable that occur within that expressionvoid
setIndexedVariable()
Indicate that the variable bound by this let expression should be indexable (because it is used in an appropriate filter expression)void
setRequiredType(SequenceType requiredType)
Set the required type (declared type) of the variablevoid
setSequence(Expression sequence)
Set the "sequence" expression - the one to which the variable is boundvoid
setSlotNumber(int nr)
Set the slot number for the range variablevoid
setVariableQName(StructuredQName variableName)
Set the name of the variableExpression
simplify(ExpressionVisitor visitor)
Simplify the expressionvoid
suppressValidation(int validationMode)
Suppress validation on contained element constructors, on the grounds that the parent element is already performing validation.-
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getExpressionName, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getItemType, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, optimize, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, toString, typeCheck, typeError
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Field Detail
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slotNumber
protected int slotNumber
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sequence
protected Expression sequence
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action
protected Expression action
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variableName
protected StructuredQName variableName
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requiredType
protected SequenceType requiredType
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refCount
int refCount
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Method Detail
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setRequiredType
public void setRequiredType(SequenceType requiredType)
Set the required type (declared type) of the variable- Parameters:
requiredType
- the required type
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setVariableQName
public void setVariableQName(StructuredQName variableName)
Set the name of the variable- Parameters:
variableName
- the name of the variable
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getVariableQName
public StructuredQName getVariableQName()
Get the name of the variable- Specified by:
getVariableQName
in interfaceBinding
- Returns:
- the variable name, as a QName
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getObjectName
public StructuredQName getObjectName()
Description copied from interface:InstructionInfo
Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc. This is used only where the name is known statically.- Specified by:
getObjectName
in interfaceInstructionInfo
- Overrides:
getObjectName
in classExpression
- Returns:
- the QName of the object declared or manipulated by this instruction or expression
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getRequiredType
public SequenceType getRequiredType()
Get the declared type of the variable- Specified by:
getRequiredType
in interfaceBinding
- Returns:
- the declared type
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getIntegerBoundsForVariable
public IntegerValue[] getIntegerBoundsForVariable()
If the variable is bound to an integer, get the minimum and maximum possible values. Return null if unknown or not applicable- Specified by:
getIntegerBoundsForVariable
in interfaceBinding
- Returns:
- a pair of integers containing the minimum and maximum values for the integer value; or null if the value is not an integer or the range is unknown
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getLocalSlotNumber
public int getLocalSlotNumber()
If this is a local variable held on the local stack frame, return the corresponding slot number. In other cases, return -1.- Specified by:
getLocalSlotNumber
in interfaceBinding
- Returns:
- the slot number on the local stack frame
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evaluateVariable
public ValueRepresentation evaluateVariable(XPathContext context) throws XPathException
Get the value of the range variable- Specified by:
evaluateVariable
in interfaceBinding
- Parameters:
context
- the XPath dynamic evaluation context- Returns:
- the result of evaluating the variable
- Throws:
XPathException
- if an error occurs while evaluating the variable
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setAction
public void setAction(Expression action)
Add the "return" or "satisfies" expression, and fix up all references to the range variable that occur within that expression- Parameters:
action
- the expression that occurs after the "return" keyword of a "for" expression, the "satisfies" keyword of "some/every", or the ":=" operator of a "let" expression.
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isGlobal
public final boolean isGlobal()
Indicate whether the binding is local or global. A global binding is one that has a fixed value for the life of a query or transformation; any other binding is local.
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isAssignable
public final boolean isAssignable()
Test whether it is permitted to assign to the variable using the saxon:assign extension element. This will only be for an XSLT global variable where the extra attribute saxon:assignable="yes" is present.- Specified by:
isAssignable
in interfaceBinding
- Returns:
- true if the binding is assignable
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checkForUpdatingSubexpressions
public void checkForUpdatingSubexpressions() throws XPathException
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 updateing subexpression
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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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getAction
public Expression getAction()
Get the action expression- Returns:
- the action expression (introduced by "return" or "satisfies")
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setSequence
public void setSequence(Expression sequence)
Set the "sequence" expression - the one to which the variable is bound- Parameters:
sequence
- the expression to which the variable is bound
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getSequence
public Expression getSequence()
Get the "sequence" expression - the one to which the variable is bound- Returns:
- the expression to which the variable is bound
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setSlotNumber
public void setSlotNumber(int nr)
Set the slot number for the range variable- Parameters:
nr
- the slot number to be used
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getRequiredSlots
public int getRequiredSlots()
Get the number of slots required. Normally 1, except for a FOR expression with an AT clause, where it is 2.- Returns:
- the number of slots required
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simplify
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Simplify the expression- Overrides:
simplify
in classExpression
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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hasVariableBinding
public boolean hasVariableBinding(Binding binding)
- Overrides:
hasVariableBinding
in classExpression
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promote
public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
Promote this expression if possible- Overrides:
promote
in classExpression
- 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 expressionparent
- the containing expression in the expression tree- Returns:
- if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
- Throws:
XPathException
- if any error is detected
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suppressValidation
public void suppressValidation(int validationMode)
Suppress validation on contained element constructors, on the grounds that the parent element is already performing validation. The default implementation does nothing.- Overrides:
suppressValidation
in classExpression
- Parameters:
validationMode
- the kind of validation being performed on the parent expression
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extendBindingList
public Binding[] extendBindingList(Binding[] in)
Extend an array of variable bindings to include the binding(s) defined in this expression- Parameters:
in
- a set of variable bindings- Returns:
- a set of variable bindings including all those supplied plus this one
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promoteWhereClause
protected Expression promoteWhereClause(Binding positionBinding)
Promote a WHERE clause whose condition doesn't depend on the variable being bound. This rewrites an expression of the formlet $i := SEQ return if (C) then R else ()
to the form:
if (C) then (let $i := SEQ return R) else ()
- Parameters:
positionBinding
- the binding of the position variable if any- Returns:
- an expression in which terms from the WHERE clause that can be extracted have been extracted
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iterateSubExpressions
public java.util.Iterator<Expression> iterateSubExpressions()
Get the immediate subexpressions of this expression- Overrides:
iterateSubExpressions
in classExpression
- Returns:
- an iterator containing the sub-expressions of this expression
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replaceSubExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression- Overrides:
replaceSubExpression
in classExpression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
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addToPathMap
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
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 PathMapNodeSet to which the paths embodied in this expression should be added- Returns:
- the pathMapNodeSet representing the points in the source document that are both reachable by this expression, and that represent possible results of this 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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getVariableName
public java.lang.String getVariableName()
Get the display name of the range variable, for diagnostics only- Returns:
- the lexical QName of the range variable
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refineTypeInformation
public void refineTypeInformation(ItemType type, int cardinality, Value constantValue, int properties, ExpressionVisitor visitor, Assignation currentExpression)
Refine the type information associated with this variable declaration. This is useful when the type of the variable has not been explicitly declared (which is common); the variable then takes a static type based on the type of the expression to which it is bound. The effect of this call is to update the static expression type for all references to this variable.- Parameters:
type
- the inferred item type of the expression to which the variable is boundcardinality
- the inferred cardinality of the expression to which the variable is boundconstantValue
- the constant value to which the variable is bound (null if there is no constant value)properties
- other static properties of the expression to which the variable is boundvisitor
- an expression visitor to provide context informationcurrentExpression
- the expression that binds the variable
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addReference
public void addReference(boolean isLoopingReference)
Register a variable reference that refers to the variable bound in this expression- Specified by:
addReference
in interfaceBinding
- Parameters:
isLoopingReference
- - true if the reference occurs within a loop, such as the predicate of a filter expression
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getNominalReferenceCount
public int getNominalReferenceCount()
Get the (nominal) count of the number of references to this variable- Returns:
- zero if there are no references, one if there is a single reference that is not in a loop, some higher number if there are multiple references (or a single reference in a loop), or the special value @link RangeVariable#FILTERED} if there are any references in filter expressions that require searching.
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isIndexedVariable
public boolean isIndexedVariable()
Test whether the variable bound by this let expression should be indexable- Returns:
- true if the variable should be indexable
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replaceVariable
public void replaceVariable(Optimizer opt, Expression seq) throws XPathException
Replace all references to the variable bound by this let expression, that occur within the action expression, with the given expression- Parameters:
opt
- The optimizerseq
- the expression- Throws:
XPathException
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setIndexedVariable
public void setIndexedVariable()
Indicate that the variable bound by this let expression should be indexable (because it is used in an appropriate filter expression)
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