com.icl.saxon.expr

Class PathExpression

public class PathExpression extends NodeSetExpression

An expression that establishes a set of nodes by following relationships between nodes in the document. Specifically, it consists of a start expression which defines a set of nodes, and a Step which defines a relationship to be followed from those nodes to create a new set of nodes.
Field Summary
intdependencies
Constructor Summary
PathExpression(Expression start, Step step)
Constructor
Method Summary
voiddisplay(int level)
Diagnostic print of expression structure
NodeEnumerationenumerate(Context context, boolean sort)
Evaluate the path-expression in a given context to return a NodeSet
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

Field Detail

dependencies

int dependencies

Constructor Detail

PathExpression

public PathExpression(Expression start, Step step)
Constructor

Parameters: start A node-set expression denoting the absolute or relative set of nodes from which the navigation path should start. step The step to be followed from each node in the start expression to yield a new node-set

Method Detail

display

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

enumerate

public NodeEnumeration enumerate(Context context, boolean sort)
Evaluate the path-expression in a given context to return a NodeSet

Parameters: context the evaluation context sort true if the returned nodes 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

Returns: the simplified expression