org.apache.xml.serializer

Class EncodingInfo

java.lang.Object

org.apache.xml.serializer.EncodingInfo

public final class EncodingInfo
extends Object

Holds information about a given encoding, which is the Java name for the encoding, the equivalent ISO name.

An object of this type has two useful methods

 isInEncoding(char ch);
 

which can be called if the character is not the high one in a surrogate pair and:

 isInEncoding(char high, char low);
 

which can be called if the two characters from a high/low surrogate pair.

An EncodingInfo object is a node in a binary search tree. Such a node will answer if a character is in the encoding, and do so for a given range of unicode values (m_first to m_last). It will handle a certain range of values explicitly (m_explFirst to m_explLast). If the unicode point is before that explicit range, that is it is in the range m_first <= value < m_explFirst, then it will delegate to another EncodingInfo object for The root of such a tree, m_before. Likewise for values in the range m_explLast < value <= m_last, but delgating to m_after

Actually figuring out if a code point is in the encoding is expensive. So the purpose of this tree is to cache such determinations, and not to build the entire tree of information at the start, but only build up as much of the tree as is used during the transformation.

This Class is not a public API, and should only be used internally within the serializer.

This class is not a public API.

Constructor Summary

Constructors

Constructor and Description
EncodingInfo(String name, String javaName, char highChar) Create an EncodingInfo object based on the ISO name and Java name.

Method Summary

Modifier and Type	Method and Description
char	getHighChar() This method exists for performance reasons.
boolean	isInEncoding(char ch) This is not a public API.
boolean	isInEncoding(char high, char low) This is not a public API.

Methods inherited from class java.lang.Object

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

Constructor Detail

EncodingInfo

public EncodingInfo(String name,
                    String javaName,
                    char highChar)

Create an EncodingInfo object based on the ISO name and Java name. If both parameters are null any character will be considered to be in the encoding. This is useful for when the serializer is in temporary output state, and has no assciated encoding.

Parameters:

name - reference to the ISO name.

javaName - reference to the Java encoding name.

highChar - The char for which characters at or below this value are definately in the encoding, although for characters above this point they might be in the encoding.

Method Detail

isInEncoding

public boolean isInEncoding(char ch)

This is not a public API. It returns true if the char in question is in the encoding.

Parameters:

ch - the char in question.

This method is not a public API.

isInEncoding

public boolean isInEncoding(char high,
                            char low)

This is not a public API. It returns true if the character formed by the high/low pair is in the encoding.

Parameters:

high - a char that the a high char of a high/low surrogate pair.

low - a char that is the low char of a high/low surrogate pair.

This method is not a public API.

getHighChar

public final char getHighChar()

This method exists for performance reasons.

Except for '', if a char is less than or equal to the value returned by this method then it in the encoding.

The characters in an encoding are not contiguous, however there is a lowest group of chars starting at '
' upto and including the char returned by this method that are all in the encoding. So the char returned by this method essentially defines the lowest contiguous group.

chars above the value returned might be in the encoding, but chars at or below the value returned are definately in the encoding.

In any case however, the isInEncoding(char) method can be used regardless of the value of the char returned by this method.

If the value returned is '' it means that every character must be tested with an isInEncoding method isInEncoding(char) or isInEncoding(char, char) for surrogate pairs.

This method is not a public API.