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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.Assignation net.sf.saxon.expr.ForExpression
public class ForExpression
A ForExpression maps an expression over a sequence. This version works with range variables, it doesn't change the context information
Nested Class Summary | |
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protected static class |
ForExpression.EventMappingAction
The EventMappingAction represents the action to be taken for each item in the source sequence. |
static class |
ForExpression.MappingAction
The MappingAction represents the action to be taken for each item in the source sequence. |
Field Summary | |
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protected PositionVariable |
positionVariable
|
Fields inherited from class net.sf.saxon.expr.Assignation |
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action, requiredType, sequence, slotNumber, variableName |
Fields inherited from class net.sf.saxon.expr.Expression |
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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 |
Constructor Summary | |
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ForExpression()
Create a "for" expression (for $x at $p in SEQUENCE return ACTION) |
Method Summary | |
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void |
checkPermittedContents(SchemaType parentType,
StaticContext env,
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. |
int |
computeCardinality()
Determine the static cardinality of the expression |
Expression |
copy()
Copy an expression. |
void |
evaluatePendingUpdates(XPathContext context,
PendingUpdateList pul)
Evaluate an updating expression, adding the results to a Pending Update List. |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
protected void |
explainSpecializedAttributes(ExpressionPresenter out)
|
Binding[] |
extendBindingList(Binding[] in)
Extend an array of variable bindings to include the binding(s) defined in this expression |
int |
getConstructType()
Get the type of this expression for use in tracing and diagnostics |
String |
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user. |
int |
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). |
IntegerValue[] |
getIntegerBounds()
For an expression that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis. |
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the items returned by the expression, if possible |
PositionVariable |
getPositionVariable()
|
StructuredQName |
getPositionVariableName()
Get the name of the position variable |
protected int |
getRangeVariableCardinality()
Get the cardinality of the range variable |
int |
getRequiredSlots()
Get the number of slots required. |
boolean |
hasLoopingSubexpression(Expression child)
Given an expression that is an immediate child of this expression, test whether the evaluation of the parent expression causes the child expression to be evaluated repeatedly |
boolean |
hasVariableBinding(Binding binding)
|
boolean |
isVacuousExpression()
Determine whether this is a vacuous expression as defined in the XQuery update specification |
SequenceIterator |
iterate(XPathContext context)
Iterate over the sequence of values |
EventIterator |
iterateEvents(XPathContext context)
Deliver the result of the expression as a sequence of events. |
int |
markTailFunctionCalls(StructuredQName qName,
int arity)
Mark tail function calls: only possible if the for expression iterates zero or one times. |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Optimize the expression |
void |
process(XPathContext context)
Process this expression as an instruction, writing results to the current outputter |
void |
setPositionVariable(PositionVariable decl)
Set the reference to the position variable (XQuery only) |
void |
setSlotNumber(int nr)
Set the slot number for the range variable |
String |
toString()
The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
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protected PositionVariable positionVariable
Constructor Detail |
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public ForExpression()
Method Detail |
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public String getExpressionName()
getExpressionName
in class Expression
public void setPositionVariable(PositionVariable decl)
decl
- the range variable declaration for the position variablepublic PositionVariable getPositionVariable()
public boolean hasVariableBinding(Binding binding)
hasVariableBinding
in class Assignation
public StructuredQName getPositionVariableName()
public void setSlotNumber(int nr)
setSlotNumber
in class Assignation
nr
- the slot number allocated to the range variable on the local stack frame.
This implicitly allocates the next slot number to the position variable if there is one.public int getRequiredSlots()
getRequiredSlots
in class Assignation
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
typeCheck
in class Expression
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 to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)protected int getRangeVariableCardinality()
public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
optimize
in class Expression
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 to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public IntegerValue[] getIntegerBounds()
getIntegerBounds
in class Expression
public boolean hasLoopingSubexpression(Expression child)
hasLoopingSubexpression
in class Expression
child
- the immediate subexpression
public Expression copy()
copy
in class Expression
public int markTailFunctionCalls(StructuredQName qName, int arity)
markTailFunctionCalls
in class Expression
qName
- the name of the functionarity
- the arity (number of parameters) of the function
UserFunctionCall.NOT_TAIL_CALL
if no tail call was found;
UserFunctionCall.FOREIGN_TAIL_CALL
if a tail call on a different function was found;public Binding[] extendBindingList(Binding[] in)
extendBindingList
in class Assignation
in
- a set of variable bindings
public boolean isVacuousExpression()
isVacuousExpression
in class Expression
public int getImplementationMethod()
getImplementationMethod
in class Expression
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public void checkPermittedContents(SchemaType parentType, StaticContext env, boolean whole) throws XPathException
checkPermittedContents
in class Expression
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 typeenv
- the static contextwhole
- 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
XPathException
- if the value delivered by this expression cannot be part of the content model
of the given typepublic SequenceIterator iterate(XPathContext context) throws XPathException
iterate
in class Expression
context
- supplies the context for evaluation
XPathException
- if any dynamic error occurs evaluating the
expressionpublic EventIterator iterateEvents(XPathContext context) throws XPathException
iterateEvents
in class Expression
context
- The dynamic evaluation context
XPathException
- if a dynamic error occurs during expression evaluationpublic void process(XPathContext context) throws XPathException
process
in class Expression
context
- The dynamic context, giving access to the current node,
the current variables, etc.
XPathException
- if a dynamic error occurspublic void evaluatePendingUpdates(XPathContext context, PendingUpdateList pul) throws XPathException
evaluatePendingUpdates
in class Expression
context
- the XPath dynamic evaluation contextpul
- the pending update list to which the results should be written
XPathException
- if evaluation failspublic ItemType getItemType(TypeHierarchy th)
getItemType
in class Expression
th
- the type hierarchy cache
public int computeCardinality()
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public String toString()
toString
in class Expression
public void explain(ExpressionPresenter out)
explain
in class Expression
out
- the expression presenter used to display the structureprotected void explainSpecializedAttributes(ExpressionPresenter out)
public int getConstructType()
getConstructType
in interface InstructionInfo
getConstructType
in class Expression
Location
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