org.eigenbase.xom
Class DOMElementParser

java.lang.Object
  org.eigenbase.xom.DOMElementParser

public class DOMElementParser
extends Object

DOMElementParser is a utility wrapper around DOMWrapper. Implements a parseable stream of child DOMWrappers and also provides validation on an XML document beyond the DTD.

Constructor Summary

DOMElementParser(DOMWrapper wrapper, String prefix, Class enclosure)
Constructs a new ElementParser based on an Element of the XML parse tree wrapped in a DOMWrapper, and a prefix (to be applied to all element tags except the root), and the name of the enclosing class.

Method Summary

NodeDef[]	classArray(Class elemClass, int min, int max) This function retrieves a collection of elements which are subclasses of the given class, returning them as an array.
NodeDef[]	getArray(Class elemClass, int min, int max) This function retrieves a collection of elements which are subclasses of the given class, returning them as an array.
Object	getAttribute(String attrName, String attrType, String defaultValue, String[] values, boolean required) Retrieve an Attribute from the parser.
NodeDef	getElement(Class elementClass, boolean required) This function retrieves an Element from this parser, advancing the parser if the element is found.
static Class	getPluginClass(Class managerClass) Get a Class object representing a plugin class, given a manager class that implements the static method getXMLDefClass().
static Class	getPluginClass(String packageName, String className) Get a Class object representing a plugin class, identified either directly by a Java package and Java class name, or indirectly by a Java package and Java class which defines a method called getXMLDefClass() to return the appropriate class.
String	getString(String elementName, boolean required) This function retrieves a String element from this parser, advancing the parser if the element is found.
String[]	getStringArray(String elemName, int min, int max) This function returns a collection of String elements of the given name, returning them as an array.
String	getText() This function is used to return a CDATA section as text.
int	lastOptionIndex() Returns the option index of the element returned through the last requiredOption call.
DOMWrapper[]	optionalArray(String elemName, int min, int max) This function retrieves a collection of elements with the given name, returning them as an array.
String	optionalAttribute(String attrName) This function retrieves an optional Attribute by name from the current Element.
Boolean	optionalBooleanAttribute(String attrName) This function retrieves an optional Attribute by name from the current Element, converting it to an Boolean.
Double	optionalDoubleAttribute(String attrName) This function retrieves an optional Attribute by name from the current Element, converting it to a Double.
DOMWrapper	optionalElement(String elementName) This function retrieves an optional Element from this parser, advancing the parser if the element is found.
Integer	optionalIntegerAttribute(String attrName) This function retrieves an optional Attribute by name from the current Element, converting it to an Integer.
String	optionalString(String elementName) This function retrieves an optional String element from this parser, advancing the parser if the element is found.
String	requiredAttribute(String attrName) This function retrieves a required Attribute by name from the current Element.
Boolean	requiredBooleanAttribute(String attrName) This function retrieves an required Attribute by name from the current Element, converting it to a Boolean.
NodeDef	requiredClass(Class classTemplate) This function retrieves a required Element of a specific class from this parser, advancing the parser after the read.
static String	requiredDefAttribute(DOMWrapper wrapper, String attrName, String defaultVal) This static version of requiredAttribute uses any element definition as a basis for the attribute.
DOMWrapper	requiredElement(String elementName) This function retrieves a required Element from this parser, advancing the parser after the read.
Integer	requiredIntegerAttribute(String attrName) This function retrieves an required Attribute by name from the current Element, converting it to an Integer.
DOMWrapper	requiredOption(String[] elementNames) This function retrieves a required element which may have one of a number of names.
String	requiredString(String elementName) This function retrieves a required String element from this parser, advancing the parser after the read.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DOMElementParser

public DOMElementParser(DOMWrapper wrapper,
                        String prefix,
                        Class enclosure)
                 throws XOMException

Constructs a new ElementParser based on an Element of the XML parse tree wrapped in a DOMWrapper, and a prefix (to be applied to all element tags except the root), and the name of the enclosing class.

Throws:

XOMException

Parameters:

wrapper - a DOMWrapper representing the section of the XML parse tree to traverse.

Method Detail

requiredString

public String requiredString(String elementName)
                      throws XOMException

This function retrieves a required String element from this parser, advancing the parser after the read.

Throws:

XOMException - if there is no element with the given name.

Parameters:

elementName - the name of the element to retrieve.

Returns:

the String value stored inside the element to retrieve.

optionalString

public String optionalString(String elementName)
                      throws XOMException

This function retrieves an optional String element from this parser, advancing the parser if the element is found. If no element of the correct name is found, this function returns null.

Throws:

XOMException

Parameters:

elementName - the name of the element to retrieve.

Returns:

the String value stored inside the element to retrieve.

requiredElement

public DOMWrapper requiredElement(String elementName)
                           throws XOMException

This function retrieves a required Element from this parser, advancing the parser after the read.

Throws:

XOMException - if there is no element with the given name.

Parameters:

elementName - the name of the element to retrieve.

Returns:

the DOMWrapper to retrieve.

getText

public String getText()

This function is used to return a CDATA section as text. It does no parsing.

Returns:

the contents of the CDATA element as text.

optionalElement

public DOMWrapper optionalElement(String elementName)
                           throws XOMException

This function retrieves an optional Element from this parser, advancing the parser if the element is found. If no element of the correct name is found, this function returns null.

Throws:

XOMException

Parameters:

elementName - the name of the element to retrieve.

Returns:

the DOMWrapper to retreive, or null if none found.

requiredOption

public DOMWrapper requiredOption(String[] elementNames)
                          throws XOMException

This function retrieves a required element which may have one of a number of names. The parser is advanced after the read.

Throws:

XOMException - if there are no more elements to read or if the next element's name is not in the elementNames list.

Parameters:

elementNames - an array of allowed names. Names are compared in a case-insensitive fashion.

Returns:

the first element with one of the given names.

requiredClass

public NodeDef requiredClass(Class classTemplate)
                      throws XOMException

This function retrieves a required Element of a specific class from this parser, advancing the parser after the read. The class must be derived from ElementDef.

Throws:

XOMException

lastOptionIndex

public int lastOptionIndex()

Returns the option index of the element returned through the last requiredOption call.

requiredAttribute

public String requiredAttribute(String attrName)
                         throws XOMException

This function retrieves a required Attribute by name from the current Element.

Throws:

XOMException - if no attribute of this name is set.

Parameters:

attrName - the name of the attribute.

Returns:

the String value of the attribute.

requiredDefAttribute

public static String requiredDefAttribute(DOMWrapper wrapper,
                                          String attrName,
                                          String defaultVal)
                                   throws XOMException

This static version of requiredAttribute uses any element definition as a basis for the attribute. It is used by Plugin definitions to return attributes before the parser is created.

Throws:

XOMException - if no attribute of this name is set.

Parameters:

wrapper - the Element in which to find the attribute.

attrName - the name of the attribute to retrieve.

defaultVal - the default value of the attribute to retrieve.

optionalAttribute

public String optionalAttribute(String attrName)
                         throws XOMException

This function retrieves an optional Attribute by name from the current Element.

Throws:

XOMException

Parameters:

attrName - the name of the attribute.

Returns:

the String value of the attribute, or null if the attribute is not set.

optionalIntegerAttribute

public Integer optionalIntegerAttribute(String attrName)
                                 throws XOMException

This function retrieves an optional Attribute by name from the current Element, converting it to an Integer.

Throws:

XOMException - if the value is set to an illegal integer value.

Parameters:

attrName - the name of the attribute.

Returns:

the Integer value of the attribute, or null if the attribute is not set.

optionalDoubleAttribute

public Double optionalDoubleAttribute(String attrName)
                               throws XOMException

This function retrieves an optional Attribute by name from the current Element, converting it to a Double.

Throws:

XOMException - if the value is set to an illegal double value.

Parameters:

attrName - the name of the attribute.

Returns:

the Double value of the attribute, or null if the attribute is not set.

requiredIntegerAttribute

public Integer requiredIntegerAttribute(String attrName)
                                 throws XOMException

This function retrieves an required Attribute by name from the current Element, converting it to an Integer.

Throws:

XOMException - if the value is not set, or is set to an illegal integer value.

Parameters:

attrName - the name of the attribute.

Returns:

the Integer value of the attribute.

optionalBooleanAttribute

public Boolean optionalBooleanAttribute(String attrName)
                                 throws XOMException

This function retrieves an optional Attribute by name from the current Element, converting it to an Boolean. The string value "true" (in any case) is considered TRUE. Any other value is considered false.

Throws:

XOMException - if the value is set to an illegal integer value.

Parameters:

attrName - the name of the attribute.

Returns:

the Boolean value of the attribute, or null if the attribute is not set.

requiredBooleanAttribute

public Boolean requiredBooleanAttribute(String attrName)
                                 throws XOMException

This function retrieves an required Attribute by name from the current Element, converting it to a Boolean. The string value "true" (in any case) is considered TRUE. Any other value is considered false.

Throws:

XOMException

Parameters:

attrName - the name of the attribute.

Returns:

the Boolean value of the attribute.

optionalArray

public DOMWrapper[] optionalArray(String elemName,
                                  int min,
                                  int max)
                           throws XOMException

This function retrieves a collection of elements with the given name, returning them as an array.

Throws:

XOMException - if there are fewer than min or more than max elements with the name elemName.

Parameters:

elemName - the element name.

min - the minimum number of elements required in the array. Set this parameter to 0 to indicate no minimum.

max - the maximum number of elements allowed in the array. Set this parameter to 0 to indicate no maximum.

Returns:

an Element array containing the discovered elements.

classArray

public NodeDef[] classArray(Class elemClass,
                            int min,
                            int max)
                     throws XOMException

This function retrieves a collection of elements which are subclasses of the given class, returning them as an array. The array will contain ElementDef objects automatically constructed to be of the correct class.

Throws:

XOMException - if there are fewer than min or more than max elements with the name elemName.

Parameters:

elemClass - the element class.

min - the minimum number of elements required in the array. Set this parameter to 0 to indicate no minimum.

max - the maximum number of elements allowed in the array. Set this parameter to 0 to indicate no maximum.

Returns:

an ElementDef array containing the discovered elements.

getElement

public NodeDef getElement(Class elementClass,
                          boolean required)
                   throws XOMException

This function retrieves an Element from this parser, advancing the parser if the element is found. The Element's corresponding ElementDef class is looked up and its constructor is called automatically. If the requested Element is not found the function returns null unless required is set to true. In this case, a XOMException is thrown.

Throws:

XOMException - if required is true and the element could not be found.

Parameters:

elementClass - the Class of the element to retrieve.

required - true to throw an exception if the element is not found, false to simply return null.

Returns:

the element, as an ElementDef, or null if it is not found and required is false.

getArray

public NodeDef[] getArray(Class elemClass,
                          int min,
                          int max)
                   throws XOMException

This function retrieves a collection of elements which are subclasses of the given class, returning them as an array. The array will contain ElementDef objects automatically constructed to be of the correct class.

Throws:

XOMException - if there are fewer than min or more than max elements with the name elemName.

Parameters:

elemClass - the element class.

min - the minimum number of elements required in the array. Set this parameter to 0 to indicate no minimum.

max - the maximum number of elements allowed in the array. Set this parameter to 0 to indicate no maximum.

Returns:

an ElementDef array containing the discovered elements.

getString

public String getString(String elementName,
                        boolean required)
                 throws XOMException

This function retrieves a String element from this parser, advancing the parser if the element is found. If no element of the correct name is found, this function returns null, unless required is true, in which case a XOMException is thrown.

Throws:

XOMException

Parameters:

elementName - the name of the element to retrieve.

required - true to throw an exception if the element is not found, false to simply return null.

Returns:

the String value stored inside the element to retrieve, or null if no element with the given elementName could be found.

getStringArray

public String[] getStringArray(String elemName,
                               int min,
                               int max)
                        throws XOMException

This function returns a collection of String elements of the given name, returning them as an array.

Throws:

XOMException - if there are fewer than min or more than max elements with the name elemName.

Parameters:

elemName - the element name.

min - the minimum number of elements required in the array. Set this parameter to 0 to indicate no minimum.

max - the maximum number of elements allowed in the array. Set this parameter to 0 to indicate no maximum.

Returns:

a String array containing the discovered elements.

getPluginClass

public static Class getPluginClass(String packageName,
                                   String className)
                            throws XOMException

Get a Class object representing a plugin class, identified either directly by a Java package and Java class name, or indirectly by a Java package and Java class which defines a method called getXMLDefClass() to return the appropriate class.

Throws:

XOMException - if the plugin class cannot be located or if the designated class is not suitable as a plugin class.

Parameters:

packageName - the name of the Java package containing the plugin class.

className - the name of the plugin definition class.

getPluginClass

public static Class getPluginClass(Class managerClass)
                            throws XOMException

Get a Class object representing a plugin class, given a manager class that implements the static method getXMLDefClass().

Throws:

XOMException

Parameters:

managerClass - any Class that implements getXMLDefClass.

Returns:

the plugin Class.

getAttribute

public Object getAttribute(String attrName,
                           String attrType,
                           String defaultValue,
                           String[] values,
                           boolean required)
                    throws XOMException

Retrieve an Attribute from the parser. The Attribute may be of any Java class, provided that the class supports a constructor from the String class. The Attribute's value will be returned as an Object, which must then be cast to the appropraite type. If the attribute is not defined and has no default, either null is returned (if required is false), or a XOMException is thrown (if required is true).

Throws:

XOMException

Parameters:

attrName - the name of the attribute to retreive.

attrType - a String naming a Java Class to serve as the type. If attrType contains a "." character, the class is looked up directly from the type name. Otherwise, the class is looked up in the java.lang package. Finally, the class must have a constructor which takes a String as an argument.

defaultValue - the default value for this attribute. If values is set, the defaultValue must also be one of the set of values. defaultValue may be null.

values - an array of possible values for the attribute. If this parameter is not null, then the attribute's value must be one of the listed set of values or an exception will be thrown.

required - if set, then this function will throw an exception if the attribute has no value and defaultValue is null.

Returns:

the Attribute's value as an Object. The actual class of this object is determined by attrType.