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java.lang.Object | +--org.jaxen.BaseXPath
Base functionality for all concrete, implementation-specific XPaths.
This class provides generic functionalty for further-defined implementation-specific XPaths.
If you want to adapt the Jaxen engine so that it can traverse your own
object model then this is a good base class to derive from.
Typically you only really need to provide your own
Navigator
implementation.
XPath for dom4j
,
XPath for JDOM
,
XPath for W3C DOM
,
XPath for Electric XML
, Serialized FormConstructor Summary | |
protected |
BaseXPath(String xpathExpr)
Construct given an XPath expression string. |
|
BaseXPath(String xpathExpr,
Navigator navigator)
Construct given an XPath expression string. |
Method Summary | |
void |
addNamespace(String prefix,
String uri)
Add a namespace prefix-to-URI mapping for this XPath expression. |
boolean |
booleanValueOf(Object node)
Retrieve a boolean-value interpretation of this XPath expression when evaluated against a given context. |
protected FunctionContext |
createFunctionContext()
Create a default FunctionContext . |
protected NamespaceContext |
createNamespaceContext()
Create a default NamespaceContext . |
protected VariableContext |
createVariableContext()
Create a default VariableContext . |
String |
debug()
Returns the string version of this xpath. |
Object |
evaluate(Object node)
Evaluate this XPath against a given context. |
protected Context |
getContext(Object node)
Create a Context wrapper for the provided
implementation-specific object. |
protected ContextSupport |
getContextSupport()
Retrieve the ContextSupport aggregation of
NamespaceContext , FunctionContext ,
VariableContext , and Navigator . |
FunctionContext |
getFunctionContext()
Retrieve the FunctionContext used by this XPath
expression. |
NamespaceContext |
getNamespaceContext()
Retrieve the NamespaceContext used by this XPath
expression. |
Navigator |
getNavigator()
Retrieve the XML object-model-specific Navigator
for us in evaluating this XPath expression. |
Expr |
getRootExpr()
Retrieve the root expression of the internal compiled form of this XPath expression. |
VariableContext |
getVariableContext()
Retrieve the VariableContext used by this XPath
expression. |
Number |
numberValueOf(Object node)
Retrieve a number-value interpretation of this XPath expression when evaluated against a given context. |
List |
selectNodes(Object node)
Select all nodes that are selectable by this XPath expression. |
protected List |
selectNodesForContext(Context context)
Select all nodes that are selectable by this XPath expression on the given Context object. |
Object |
selectSingleNode(Object node)
Select only the first node that is selectable by this XPath expression. |
protected Object |
selectSingleNodeForContext(Context context)
Select only the first node that is selectable by this XPath expression. |
void |
setFunctionContext(FunctionContext functionContext)
Set a FunctionContext for use with this XPath
expression. |
void |
setNamespaceContext(NamespaceContext namespaceContext)
Set a NamespaceContext for use with this
XPath expression. |
void |
setVariableContext(VariableContext variableContext)
Set a VariableContext for use with this XPath
expression. |
String |
stringValueOf(Object node)
Retrieve a string-value interpretation of this XPath expression when evaluated against a given context. |
String |
toString()
Return the normalized string of this XPath expression. |
String |
valueOf(Object node)
Retrieve a string-value interpretation of this XPath expression when evaluated against a given context. |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
protected BaseXPath(String xpathExpr) throws JaxenException
xpathExpr
- The XPath expression.JaxenException
- if there is a syntax error while
parsing the expression.public BaseXPath(String xpathExpr, Navigator navigator) throws JaxenException
xpathExpr
- The XPath expression.navigator
- the XML navigator to useJaxenException
- if there is a syntax error while
parsing the expression.Method Detail |
public Object evaluate(Object node) throws JaxenException
The context of evaluation my be a document, an element, or a set of elements.
If the expression evaluates to a single primitive
(String, Number or Boolean) type, it is returned
directly. Otherwise, the returned value is a
List (a node-set
, in the terms of the
specification) of values.
When using this method, one must be careful to
test the class of the returned objects, and of
each of the composite members if a List
is returned. If the returned members are XML entities,
they will be the actual Document
,
Element
or Attribute
objects
as defined by the concrete XML object-model implementation,
directly from the context document. This does not
return copies of anything, but merely returns
references to entities within the source document.
evaluate
in interface XPath
node
- The node, nodeset or Context object for evaluation. This value can be null.public List selectNodes(Object node) throws JaxenException
NOTE: In most cases, nodes will be returned
in document-order, as defined by the XML Canonicalization
specification. The exception occurs when using XPath
expressions involving the union
operator
(denoted with the pipe '|' character).
selectNodes
in interface XPath
node
- The node, nodeset or Context object for evaluation. This value can be null.node-set
of all items selected
by this XPath expression.selectSingleNode(java.lang.Object)
public Object selectSingleNode(Object node) throws JaxenException
union
operator
(denoted with the pipe '|' character).
selectSingleNode
in interface XPath
node
- The node, nodeset or Context object for evaluation. This value can be null.node-set
of all items selected
by this XPath expression.selectNodes(java.lang.Object)
public String valueOf(Object node) throws JaxenException
XPath
The string-value of the expression is determined per
the string(..)
core function as defined
in the XPath specification. This means that an expression
that selects more than one nodes will return the string value
of the first node in the node set..
valueOf
in interface XPath
org.jaxen.XPath
The
- node, nodeset or Context object for evaluation. This value can be nullpublic String stringValueOf(Object node) throws JaxenException
XPath
The string-value of the expression is determined per
the string(..)
core function as defined
in the XPath specification. This means that an expression
that selects more than one nodes will return the string value
of the first node in the node set..
stringValueOf
in interface XPath
org.jaxen.XPath
The
- node, nodeset or Context object for evaluation. This value can be nullpublic boolean booleanValueOf(Object node) throws JaxenException
The boolean-value of the expression is determined per
the boolean(..)
core function as defined
in the XPath specification. This means that an expression
that selects zero nodes will return false
,
while an expression that selects one-or-more nodes will
return true
.
booleanValueOf
in interface XPath
node
- The node, nodeset or Context object for evaluation. This value can be null.public Number numberValueOf(Object node) throws JaxenException
The number-value of the expression is determined per
the number(..)
core function as defined
in the XPath specification. This means that if this
expression selects multiple nodes, the number-value
of the first node is returned.
numberValueOf
in interface XPath
node
- The node, nodeset or Context object for evaluation. This value can be null.public void addNamespace(String prefix, String uri) throws JaxenException
Namespace prefix-to-URI mappings in an XPath are independant of those used within any document. Only the mapping explicitly added to this XPath will be available for resolving the XPath expression.
This is a convenience method for adding mappings to the
default NamespaceContext
in place for this XPath.
If you have installed a specific custom NamespaceContext
,
then this method will throw a JaxenException
.
addNamespace
in interface XPath
prefix
- The namespace prefix.uri
- The namespace URI.JaxenException
- If a NamespaceContext
used by this XPath has been explicitly installed.public void setNamespaceContext(NamespaceContext namespaceContext)
NamespaceContext
for use with this
XPath expression.
A NamespaceContext
is responsible for translating
namespace prefixes within the expression into namespace URIs.
setNamespaceContext
in interface XPath
namespaceContext
- The NamespaceContext
to
install for this expression.NamespaceContext
,
NamespaceContext.translateNamespacePrefixToUri(java.lang.String)
public void setFunctionContext(FunctionContext functionContext)
FunctionContext
for use with this XPath
expression.
A FunctionContext
is responsible for resolving
all function calls used within the expression.
setFunctionContext
in interface XPath
functionContext
- The FunctionContext
to
install for this expression.FunctionContext
,
FunctionContext.getFunction(java.lang.String, java.lang.String, java.lang.String)
public void setVariableContext(VariableContext variableContext)
VariableContext
for use with this XPath
expression.
A VariableContext
is responsible for resolving
all variables referenced within the expression.
setVariableContext
in interface XPath
variableContext
- The VariableContext
to
install for this expression.VariableContext
,
VariableContext.getVariableValue(java.lang.String, java.lang.String, java.lang.String)
public NamespaceContext getNamespaceContext()
NamespaceContext
used by this XPath
expression.
A FunctionContext
is responsible for resolving
all function calls used within the expression.
If this XPath expression has not previously had a NamespaceContext
installed, a new default NamespaceContext
will be created,
installed and returned.
getNamespaceContext
in interface XPath
NamespaceContext
used by this expression.NamespaceContext
public FunctionContext getFunctionContext()
FunctionContext
used by this XPath
expression.
A FunctionContext
is responsible for resolving
all function calls used within the expression.
If this XPath expression has not previously had a FunctionContext
installed, a new default FunctionContext
will be created,
installed and returned.
getFunctionContext
in interface XPath
FunctionContext
used by this expression.FunctionContext
public VariableContext getVariableContext()
VariableContext
used by this XPath
expression.
A VariableContext
is responsible for resolving
all variables referenced within the expression.
If this XPath expression has not previously had a VariableContext
installed, a new default VariableContext
will be created,
installed and returned.
getVariableContext
in interface XPath
VariableContext
used by this expression.VariableContext
public Expr getRootExpr()
Internally, Jaxen maintains a form of Abstract Syntax Tree (AST) to represent the structure of the XPath expression. This is normally not required during normal consumer-grade usage of Jaxen. This method is provided for hard-core users who wish to manipulate or inspect a tree-based version of the expression.
public String toString()
During parsing, the XPath expression is normalized, removing abbreviations and other convenience notation. This method returns the fully normalized representation of the original expression.
toString
in class Object
public String debug()
toString()
protected Context getContext(Object node)
Context
wrapper for the provided
implementation-specific object.node
- The implementation-specific object
to be used as the context.Context
wrapper around the object.protected ContextSupport getContextSupport()
ContextSupport
aggregation of
NamespaceContext
, FunctionContext
,
VariableContext
, and Navigator
.ContextSupport
for this
XPath expression.public Navigator getNavigator()
Navigator
for us in evaluating this XPath expression.getNavigator
in interface XPath
Navigator
.protected FunctionContext createFunctionContext()
FunctionContext
.FunctionContext
.protected NamespaceContext createNamespaceContext()
NamespaceContext
.NamespaceContext
instance.protected VariableContext createVariableContext()
VariableContext
.VariableContext
instance.protected List selectNodesForContext(Context context) throws JaxenException
NOTE: In most cases, nodes will be returned
in document-order, as defined by the XML Canonicalization
specification. The exception occurs when using XPath
expressions involving the union
operator
(denoted with the pipe '|' character).
context
- is the Context which gets evaluated.node-set
of all items selected
by this XPath expression.protected Object selectSingleNodeForContext(Context context) throws JaxenException
union
operator
(denoted with the pipe '|' character).
context
- is the Context which gets evaluated.node-set
of all items selected
by this XPath expression.selectNodesForContext(org.jaxen.Context)
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