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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 predicateMethod 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 Expression
simplify
in class ComputedExpression
XPathException
- if any failure occurspublic 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 Expression
promote
in class ComputedExpression
offer
- details of the promotion that is possible
XPathException
- if any error is detectedpublic java.util.Iterator iterateSubExpressions()
iterateSubExpressions
in interface Expression
iterateSubExpressions
in class ComputedExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in interface Container
replaceSubExpression
in class ComputedExpression
original
- the original subexpressionreplacement
- the replacement subexpression
public int computeCardinality()
computeCardinality
in class ComputedExpression
public int computeSpecialProperties()
computeSpecialProperties
in class ComputedExpression
public 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 Expression
iterate
in class ComputedExpression
context
- 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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