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java.lang.Objectnet.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.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 |
| Fields inherited from class net.sf.saxon.expr.ComputedExpression |
locationId, staticProperties |
| Fields inherited from interface net.sf.saxon.expr.Expression |
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD |
| Constructor Summary | |
FilterExpression(Expression start,
Expression filter)
Constructor |
|
| Method Summary | |
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). |
void |
display(int level,
java.io.PrintStream out,
Configuration config)
Diagnostic print of expression structure |
boolean |
equals(java.lang.Object other)
Is this expression the same as another expression? |
Expression |
getBaseExpression()
Get the underlying expression |
Expression |
getFilter()
Get the filter expression |
ItemType |
getItemType(TypeHierarchy th)
Get the data type of the items returned |
int |
hashCode()
get HashCode for comparing two expressions |
boolean |
isIndexable()
Test whether the filter is amenable to indexing |
boolean |
isPositional(TypeHierarchy th)
Determine if the filter is positional |
SequenceIterator |
iterate(XPathContext context)
Iterate over the results, returning them in the correct order |
java.util.Iterator |
iterateSubExpressions()
Get the immediate subexpressions of this expression |
Expression |
optimize(Optimizer opt,
StaticContext env,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
Expression |
promote(PromotionOffer offer)
Promote this expression if possible |
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression |
simplify(StaticContext env)
Simplify an expression |
Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Type-check the expression |
| Methods inherited from class java.lang.Object |
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
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 predicate| Method Detail |
public ItemType getItemType(TypeHierarchy th)
th -
public Expression getBaseExpression()
public Expression getFilter()
public boolean isPositional(TypeHierarchy th)
th - the Type Hierarchy (for cached access to type information)
public Expression simplify(StaticContext env)
throws XPathException
simplify in interface Expressionsimplify in class ComputedExpressionXPathException - if any failure occurs
public Expression typeCheck(StaticContext env,
ItemType contextItemType)
throws XPathException
env - the static contextcontextItemType - 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
public Expression optimize(Optimizer opt,
StaticContext env,
ItemType 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.
opt - the optimizer in use. This provides access to supporting functions; it also allows
different optimization strategies to be used in different circumstances.env - the static context of the expressioncontextItemType - 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
StaticError - if an error is discovered during this phase
(typically a type error)
XPathException
public Expression promote(PromotionOffer offer)
throws XPathException
promote in interface Expressionpromote in class ComputedExpressionoffer - details of the promotion that is possible
XPathException - if any error is detectedpublic java.util.Iterator iterateSubExpressions()
iterateSubExpressions in interface ExpressioniterateSubExpressions in class ComputedExpression
public boolean replaceSubExpression(Expression original,
Expression replacement)
replaceSubExpression in interface ContainerreplaceSubExpression in class ComputedExpressionoriginal - the original subexpressionreplacement - the replacement subexpression
public int computeCardinality()
computeCardinality in class ComputedExpressionpublic int computeSpecialProperties()
computeSpecialProperties in class ComputedExpressionpublic boolean equals(java.lang.Object other)
other - the expression to be compared with this one
public int hashCode()
public SequenceIterator iterate(XPathContext context)
throws XPathException
iterate in interface Expressioniterate in class ComputedExpressioncontext - the dynamic context for the evaluation
XPathException - if any dynamic error occurspublic boolean isIndexable()
public int computeDependencies()
computeDependencies in class ComputedExpression
public void display(int level,
java.io.PrintStream out,
Configuration config)
level - the indentation levelout - config -
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