com.icl.saxon.expr

Class 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)
Constructor Summary
FilterExpression(Expression start, Expression filter)
Constructor
Method Summary
voiddisplay(int level)
Diagnostic print of expression structure
NodeEnumerationenumerate(Context context, boolean sort)
Evaluate the filter expression in a given context to return a Node Enumeration
intgetDependencies()
Determine which aspects of the context the expression depends on.
booleanisContextDocumentNodeSet()
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.
Expressionreduce(int dep, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Expressionsimplify()
Simplify an expression

Constructor Detail

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

Method Detail

display

public void display(int level)
Diagnostic print of expression structure

enumerate

public NodeEnumeration enumerate(Context context, boolean sort)
Evaluate the filter expression in a given context to return a Node Enumeration

Parameters: context the evaluation context sort 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

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.

reduce

public Expression reduce(int dep, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

Parameters: dep The dependencies to be removed context The context to be used for the partial evaluation

Returns: a new expression that does not have any of the specified dependencies

simplify

public Expression simplify()
Simplify an expression