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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.FilterExpression
public final class FilterExpression
A FilterExpression contains a base expression and a filter predicate, which may be an integer expression (positional filter), or a boolean expression (qualifier)
Field Summary | |
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static int |
FILTERED
|
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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FilterExpression(Expression start,
Expression filter)
Constructor |
Method Summary | |
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PathMap.PathMapNodeSet |
addToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. |
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. |
Expression |
getControlledExpression()
Get the subexpression that is evaluated in the new context |
Expression |
getControllingExpression()
Get the underlying expression |
String |
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user. |
Expression |
getFilter()
Get the filter expression |
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)
Get the data type of the items returned |
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 |
boolean |
isFilterIsPositional()
|
boolean |
isIndependentNumericFilter()
Determine whether the filter is a simple independent numeric, that is, an expression that satisfies the following conditions: (a) its value is numeric; (b) the value does not depend on the context item or position; (c) the cardinality is zero or one. |
boolean |
isPositional(TypeHierarchy th)
Determine if the filter is positional |
boolean |
isSimpleBooleanFilter()
Test if the filter always returns a singleton boolean |
SequenceIterator |
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 |
simplify(ExpressionVisitor visitor)
Simplify an expression |
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, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
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public static final int FILTERED
Constructor Detail |
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public FilterExpression(Expression start, Expression filter)
start
- A node-set expression denoting the absolute or relative set of nodes from which the
navigation path should start.filter
- An expression defining the filter predicateMethod Detail |
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public String getExpressionName()
getExpressionName
in class Expression
public ItemType getItemType(TypeHierarchy th)
getItemType
in class Expression
th
- the type hierarchy cache
public Expression getControllingExpression()
getControllingExpression
in interface ContextSwitchingExpression
public boolean isFilterIsPositional()
FilterExpressionCompiler
public Expression getControlledExpression()
getControlledExpression
in interface ContextSwitchingExpression
public Expression getFilter()
public boolean isPositional(TypeHierarchy th)
th
- the Type Hierarchy (for cached access to type information)
public boolean isSimpleBooleanFilter()
public boolean isIndependentNumericFilter()
public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
in class Expression
visitor
- the expression visitor
XPathException
- if any failure occurspublic Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
typeCheck
in class Expression
visitor
- the expression visitorcontextItemType
- the type of the context item for this expression
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
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
XPathException
- if an error is discovered during this phase
(typically a type error)public IntegerValue[] getIntegerBounds()
getIntegerBounds
in class Expression
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
addToPathMap
in class Expression
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the PathMapNodeSet to which the paths embodied in this expression should be added
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 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 Expression copy()
copy
in class Expression
public String toString()
toString
in class Expression
public void explain(ExpressionPresenter out)
explain
in class Expression
out
- the ExpressionPresenter to be used
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