com.icl.saxon.expr

Class UnionExpression

class UnionExpression extends NodeSetExpression

An expression representing a nodeset that is a union of two other NodeSets
Field Summary
protected Expressionp1
protected Expressionp2
Constructor Summary
UnionExpression(Expression p1, Expression p2)
Constructor
Method Summary
voiddisplay(int level)
Diagnostic print of expression structure
NodeEnumerationenumerate(Context c, boolean sort)
Evaluate the union expression.
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 dependencies, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Expressionsimplify()
Simplify an expression

Field Detail

p1

protected Expression p1

p2

protected Expression p2

Constructor Detail

UnionExpression

public UnionExpression(Expression p1, Expression p2)
Constructor

Parameters: p1 the left-hand operand p2 the right-hand operand

Method Detail

display

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

enumerate

public NodeEnumeration enumerate(Context c, boolean sort)
Evaluate the union expression. The result will always be sorted in document order, with duplicates eliminated

Parameters: c The context for evaluation sort Request the nodes in document order (they will be, regardless)

Returns: a NodeSetValue representing the union of the two operands

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 dependencies, Context context)
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

Parameters: dependencies 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

Returns: the simplified expression