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java.lang.Object net.sf.saxon.expr.Expression com.saxonica.expr.IndexedFilterExpression
public final class IndexedFilterExpression
An IndexedFilterExpression contains a base expression and a filter predicate. The base expression will always be a local variable reference. The filter will always be a Comparison, and it will have no positional dependencies
Field Summary |
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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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IndexedFilterExpression(VariableReference start,
ComparisonExpression filter,
boolean indexFirstOperand)
Constructor |
Method Summary | |
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int |
computeCardinality()
Get the static cardinality of this expression |
int |
computeDependencies()
Determine which aspects of the context the expression depends on. |
int |
computeSpecialProperties()
Get the static properties of this expression (other than its type). |
Expression |
copy()
Copy an expression. |
boolean |
equals(Object other)
Is this expression the same as another expression? |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
VariableReference |
getBaseExpression()
Get the underlying expression |
Expression |
getControlledExpression()
Get the subexpression that is evaluated in the new context |
Expression |
getControllingExpression()
Get the subexpression that sets the context item |
ComparisonExpression |
getFilter()
Get the filter expression |
ItemType |
getItemType(TypeHierarchy th)
Get the data type of the items returned |
Expression |
getSearchExpression()
Get the expression whose value we will be searching for |
Expression |
getUseExpression()
Get the expression to be indexed |
int |
hashCode()
get HashCode for comparing two expressions |
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 |
SequenceIterator<? extends Item> |
iterate(XPathContext context)
Iterate over the results, returning them in the correct order |
Iterator<Expression> |
iterateSameFocusSubExpressions()
Get the immediate sub-expressions of this expression that are evaluated with the same focus (context item, position, and size) as the parent expression. |
Iterator<Expression> |
iterateSubExpressions()
Get the immediate subexpressions of this expression |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
Expression |
promote(PromotionOffer offer,
Expression parent)
Promote this expression if possible |
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public IndexedFilterExpression(VariableReference start, ComparisonExpression filter, boolean indexFirstOperand)
start
- Variable containing the sequence of items from which the selection will take place.filter
- An expression defining the filter predicateindexFirstOperand
- true if the first operand of the filter comparison is to be indexed, false
if the second operand is to be indexedMethod Detail |
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public ItemType getItemType(TypeHierarchy th)
getItemType
in class Expression
th
- the type hierarchy cache
public VariableReference getBaseExpression()
public ComparisonExpression getFilter()
public Expression getControllingExpression()
getControllingExpression
in interface ContextSwitchingExpression
public Expression getControlledExpression()
getControlledExpression
in interface ContextSwitchingExpression
public Expression getUseExpression()
public Expression getSearchExpression()
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)public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
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.
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
public Expression copy()
copy
in class Expression
public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
promote
in class Expression
offer
- details of the promotion that is possibleparent
-
XPathException
- if any error is detectedpublic Iterator<Expression> iterateSubExpressions()
iterateSubExpressions
in class Expression
public Iterator<Expression> iterateSameFocusSubExpressions()
iterateSameFocusSubExpressions
in class Expression
public boolean hasLoopingSubexpression(Expression child)
hasLoopingSubexpression
in class Expression
child
- the immediate subexpression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in class Expression
original
- the original subexpressionreplacement
- the replacement subexpression
public int computeCardinality()
computeCardinality
in class Expression
public int computeSpecialProperties()
computeSpecialProperties
in class Expression
public boolean equals(Object other)
equals
in class Object
other
- the expression to be compared with this one
public int hashCode()
hashCode
in class Object
public SequenceIterator<? extends Item> iterate(XPathContext context) throws XPathException
iterate
in class Expression
context
- the dynamic context for the evaluation
XPathException
- if any dynamic error occurspublic int computeDependencies()
computeDependencies
in class Expression
public void explain(ExpressionPresenter out)
explain
in class Expression
out
- the expression presenter used to display the structure
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