org.apache.commons.configuration.tree
Class DefaultConfigurationKey

java.lang.Object
  org.apache.commons.configuration.tree.DefaultConfigurationKey

public class DefaultConfigurationKey

extends Object

A simple class that supports creation of and iteration on configuration keys supported by a DefaultExpressionEngine object.

For key creation the class works similar to a StringBuffer: There are several appendXXXX() methods with which single parts of a key can be constructed. All these methods return a reference to the actual object so they can be written in a chain. When using this methods the exact syntax for keys need not be known.

This class also defines a specialized iterator for configuration keys. With such an iterator a key can be tokenized into its single parts. For each part it can be checked whether it has an associated index.

Instances of this class are always associated with an instance of DefaultExpressionEngine, from which the current delimiters are obtained. So key creation and parsing is specific to this associated expression engine.

Since:

1.3

Version:

$Id: DefaultConfigurationKey.java 439648 2006-09-02 20:42:10Z oheger $

Author:

Oliver Heger

Nested Class Summary

class

DefaultConfigurationKey.KeyIterator A specialized iterator class for tokenizing a configuration key.

Constructor Summary

DefaultConfigurationKey(DefaultExpressionEngine engine)
Creates a new instance of DefaultConfigurationKey and sets the associated expression engine.

DefaultConfigurationKey(DefaultExpressionEngine engine, String key)
Creates a new instance of DefaultConfigurationKey and sets the associated expression engine and an initial key.

Method Summary

DefaultConfigurationKey	append(String property) Appends the name of a property to this key.
DefaultConfigurationKey	append(String property, boolean escape) Appends the name of a property to this key.
DefaultConfigurationKey	appendAttribute(String attr) Appends an attribute to this configuration key.
DefaultConfigurationKey	appendIndex(int index) Appends an index to this configuration key.
String	attributeName(String key) Extracts the name of the attribute from the given attribute key.
String	constructAttributeKey(String key) Decorates the given key so that it represents an attribute.
boolean	equals(Object c) Checks if two ConfigurationKey objects are equal.
DefaultExpressionEngine	getExpressionEngine() Returns the associated default expression engine.
int	hashCode() Returns the hash code for this object.
boolean	isAttributeKey(String key) Tests if the specified key represents an attribute according to the current expression engine.
DefaultConfigurationKey.KeyIterator	iterator() Returns an iterator for iterating over the single components of this configuration key.
int	length() Returns the actual length of this configuration key.
void	setExpressionEngine(DefaultExpressionEngine expressionEngine) Sets the associated expression engine.
void	setLength(int len) Sets the new length of this configuration key.
String	toString() Returns a string representation of this object.
String	trim(String key) Removes delimiters at the beginning and the end of the specified key.
String	trimLeft(String key) Removes leading property delimiters from the specified key.
String	trimRight(String key) Removes trailing property delimiters from the specified key.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DefaultConfigurationKey

public DefaultConfigurationKey(DefaultExpressionEngine engine)

Creates a new instance of DefaultConfigurationKey and sets the associated expression engine.

Parameters:

engine - the expression engine

DefaultConfigurationKey

public DefaultConfigurationKey(DefaultExpressionEngine engine,
                               String key)

Creates a new instance of DefaultConfigurationKey and sets the associated expression engine and an initial key.

Parameters:

engine - the expression engine

key - the key to be wrapped

Method Detail

getExpressionEngine

public DefaultExpressionEngine getExpressionEngine()

Returns the associated default expression engine.

Returns:

the associated expression engine

setExpressionEngine

public void setExpressionEngine(DefaultExpressionEngine expressionEngine)

Sets the associated expression engine.

Parameters:

expressionEngine - the expression engine (must not be null)

append

public DefaultConfigurationKey append(String property,
                                      boolean escape)

Appends the name of a property to this key. If necessary, a property delimiter will be added. If the boolean argument is set to true, property delimiters contained in the property name will be escaped.

Parameters:

property - the name of the property to be added

escape - a flag if property delimiters in the passed in property name should be escaped

Returns:

a reference to this object

append

public DefaultConfigurationKey append(String property)

Appends the name of a property to this key. If necessary, a property delimiter will be added. Property delimiters in the given string will not be escaped.

Parameters:

property - the name of the property to be added

Returns:

a reference to this object

appendIndex

public DefaultConfigurationKey appendIndex(int index)

Appends an index to this configuration key.

Parameters:

index - the index to be appended

Returns:

a reference to this object

appendAttribute

public DefaultConfigurationKey appendAttribute(String attr)

Appends an attribute to this configuration key.

Parameters:

attr - the name of the attribute to be appended

Returns:

a reference to this object

length

public int length()

Returns the actual length of this configuration key.

Returns:

the length of this key

setLength

public void setLength(int len)

Sets the new length of this configuration key. With this method it is possible to truncate the key, e.g. to return to a state prior calling some append() methods. The semantic is the same as the setLength() method of StringBuffer.

Parameters:

len - the new length of the key

equals

public boolean equals(Object c)

Checks if two ConfigurationKey objects are equal. The method can be called with strings or other objects, too.

Parameters:

c - the object to compare

Returns:

a flag if both objects are equal

hashCode

public int hashCode()

Returns the hash code for this object.

Returns:

the hash code

toString

public String toString()

Returns a string representation of this object. This is the configuration key as a plain string.

Returns:

a string for this object

isAttributeKey

public boolean isAttributeKey(String key)

Tests if the specified key represents an attribute according to the current expression engine.

Parameters:

key - the key to be checked

Returns:

true if this is an attribute key, false otherwise

constructAttributeKey

public String constructAttributeKey(String key)

Decorates the given key so that it represents an attribute. Adds special start and end markers. The passed in string will be modified only if does not already represent an attribute.

Parameters:

key - the key to be decorated

Returns:

the decorated attribute key

attributeName

public String attributeName(String key)

Extracts the name of the attribute from the given attribute key. This method removes the attribute markers - if any - from the specified key.

Parameters:

key - the attribute key

Returns:

the name of the corresponding attribute

trimLeft

public String trimLeft(String key)

Removes leading property delimiters from the specified key.

Parameters:

key - the key

Returns:

the key with removed leading property delimiters

trimRight

public String trimRight(String key)

Removes trailing property delimiters from the specified key.

Parameters:

key - the key

Returns:

the key with removed trailing property delimiters

trim

public String trim(String key)

Removes delimiters at the beginning and the end of the specified key.

Parameters:

key - the key

Returns:

the key with removed property delimiters

iterator

public DefaultConfigurationKey.KeyIterator iterator()

Returns an iterator for iterating over the single components of this configuration key.

Returns:

an iterator for this key