Package com.icl.saxon.expr
Class PathExpression
- 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.PathExpression
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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.
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Field Summary
Fields Modifier and Type Field Description (package private) int
dependencies
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Fields inherited from class com.icl.saxon.expr.Expression
staticContext
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Constructor Summary
Constructors Constructor Description PathExpression(Expression start, Step step)
Constructor
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
display(int level)
Diagnostic print of expression structureNodeEnumeration
enumerate(Context context, boolean sort)
Evaluate the path-expression in a given context to return a NodeSetint
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 com.icl.saxon.expr.NodeSetExpression
evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst
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Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsNumber, getStaticContext, indent, make, setStaticContext, usesCurrent
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Constructor Detail
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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
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Method Detail
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simplify
public Expression simplify() throws XPathException
Simplify an expression- Overrides:
simplify
in classExpression
- Returns:
- the simplified expression
- Throws:
XPathException
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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- Specified by:
getDependencies
in classExpression
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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 classExpression
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reduce
public Expression reduce(int dep, Context context) throws XPathException
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.- Specified by:
reduce
in classExpression
- 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
- Throws:
XPathException
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enumerate
public NodeEnumeration enumerate(Context context, boolean sort) throws XPathException
Evaluate the path-expression in a given context to return a NodeSet- Specified by:
enumerate
in classNodeSetExpression
- Parameters:
context
- the evaluation contextsort
- true if the returned nodes must be in document order- Throws:
XPathException
- when the expression does not return a nodeset.
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display
public void display(int level)
Diagnostic print of expression structure- Specified by:
display
in classExpression
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