Package org.exolab.adaptx.xpath


package org.exolab.adaptx.xpath

XPath API

Version:
$Revision: 3633 $ $Date: 2003-03-01 08:38:44 +0100 (Sat, 01 Mar 2003) $
Author:
Keith Visco
Author:
Assaf Arkin

Expressions And Results

An XPath expression is compiled using the XPath parser. To obtain a new parser instance use the static method

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newInstance
. Once obtained, the parser can be used to create XPath expressions using the
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createExpression
method. Expressions are compiled and can be reused multiple times. The parser is thread-safe and can be used to create multiple expressions concurrently.

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com.intalio.n3.xpath.XPathExpression
is an abstract class representing an XPath expression. The primary method is
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evaluate
that is used to evaluates the expression and returns the XPath result.

An XPath result is represented by the abstract class

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com.intalio.n3.xpath.XPathResult
. An XPath result can be one of the following four types:
  • A boolean result of type
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    com.intalio.n3.xpath.XPathResult#BOOLEAN
    represented by an object of type
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    com.intalio.n3.xpath.BooleanResult
    .
  • A string result of type
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    com.intalio.n3.xpath.XPathResult#STRING
    represented by an object of type
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    com.intalio.n3.xpath.StringResult
    .
  • A number result of type
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    com.intalio.n3.xpath.XPathResult#NUMBER
    represented by an object of type
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    com.intalio.n3.xpath.NumberResult
    .
  • A node-set result of type
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    com.intalio.n3.xpath.XPathResult#NODE_SET
    represented by an object of type
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    com.intalio.n3.xpath.NodeSet
    .

XPath Context

In order to evaluate an XPath expression, an XPath context is required. An XPath context provides a way to manage a stock of node-sets, resolve variable and function names, and return the size and position of the context.

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com.intalio.n3.xpath.XPathContext
provides a base implementation of an XPath context. This implementation is not thread-safe, care must be taken not to use the same context when evaluating expressions concurrently.

Impelementations may wish to extend this class and provide additional facilities for locating the document order of a node, or providing a function library.

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com.intalio.n3.xpath.Variables
provides variable bindings that can be used when evaluating an XPath expression, and
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com.intalio.n3.xpath.XPathFunction
can be used to implement extension functions.

XPath Node

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com.intalio.n3.xpath.XPathNode
is an abstract class representing a node in a document tree, on which XPath expressions can be evaluated. This abstract class provides all the services required by XPath, and enables multiple implementations to exist. It does not make use of iterators or traversals, but assumes double-linked lists are used to maintain node lists.