com.icl.saxon.expr
Class FilterExpression
java.lang.Object
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+--com.icl.saxon.expr.Expression
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+--com.icl.saxon.expr.NodeSetExpression
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+--com.icl.saxon.expr.FilterExpression
- class FilterExpression
- extends NodeSetExpression
A FilterExpression contains a base expression and a filter predicate, which may be an
integer expression (positional filter), or a boolean expression (qualifier)
Method Summary |
void |
display(int level)
Diagnostic print of expression structure |
NodeEnumeration |
enumerate(Context context,
boolean sort)
Evaluate the filter expression in a given context to return a Node Enumeration |
int |
getDependencies()
Determine which aspects of the context the expression depends on. |
boolean |
isContextDocumentNodeSet()
Determine, in the case of an expression whose data type is Value.NODESET,
whether all the nodes in the node-set are guaranteed to come from the same
document as the context node. |
Expression |
reduce(int dep,
Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies
on the context. |
Expression |
simplify()
Simplify an expression |
Methods inherited from class java.lang.Object |
, clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
FilterExpression
public FilterExpression(Expression start,
Expression filter)
- Constructor
- Parameters:
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
simplify
public Expression simplify()
throws XPathException
- Simplify an expression
- Overrides:
simplify
in class Expression
- Following copied from class:
com.icl.saxon.expr.Expression
- Returns:
- the simplified expression
enumerate
public NodeEnumeration enumerate(Context context,
boolean sort)
throws XPathException
- Evaluate the filter expression in a given context to return a Node Enumeration
- Overrides:
enumerate
in class NodeSetExpression
- Parameters:
context
- the evaluation contextsort
- true if the result must be in document order
getDependencies
public int getDependencies()
- Determine which aspects of the context the expression depends on. The result is
a bitwise-or'ed value composed from constants such as Context.VARIABLES and
Context.CURRENT_NODE
- Overrides:
getDependencies
in class Expression
reduce
public Expression reduce(int dep,
Context context)
throws XPathException
- Perform a partial evaluation of the expression, by eliminating specified dependencies
on the context.
- Overrides:
reduce
in class Expression
- Parameters:
dep
- The dependencies to be removedcontext
- The context to be used for the partial evaluation- Returns:
- a new expression that does not have any of the specified
dependencies
isContextDocumentNodeSet
public boolean isContextDocumentNodeSet()
- Determine, in the case of an expression whose data type is Value.NODESET,
whether all the nodes in the node-set are guaranteed to come from the same
document as the context node. Used for optimization.
- Overrides:
isContextDocumentNodeSet
in class Expression
display
public void display(int level)
- Diagnostic print of expression structure
- Overrides:
display
in class Expression