info.freelibrary.marc4j.converter.impl

Class ReverseCodeTable

java.lang.Object

info.freelibrary.marc4j.converter.impl.ReverseCodeTable

Direct Known Subclasses:

ReverseCodeTableGenerated, ReverseCodeTableHash

public abstract class ReverseCodeTable
extends Object

ReverseCodeTable is a set of methods to facilitate Unicode to MARC-8 character conversion, it tracks the current charset encodings that are in use, and defines abstract methods isCombining() and getCharTable()which must be overridden in a sub-class to actually implement the Unicode to MARC8 character conversion. There are two defined subclasses: ReverseCodeTableHash which reads in and parses a large XML file at runtime, and ReverseCodeTableGenerated which consists of a couple of switch statements that implement the same two methods. The code for the second of these two sub-classes, ReverseCodeTableGenerated, is generated when the marc4j jar file is created using the same XML file that ReverseCodeTableHash uses.

Author:

Robert Haschart, Corey Keith

Field Summary

Fields

Modifier and Type	Field and Description
protected String	charsetsUsed
protected byte[]	g
protected Character	lastLookupKey
protected Hashtable<Integer,char[]>	lastLookupValue

Constructor Summary

Constructors

Constructor and Description
ReverseCodeTable() Default constructor for the abstract class, allocates and initializes the structures that are used to track the current character sets in use.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	charHasMatch(Character c) Checks whether a MARC8 translation of a given Unicode character exists.
Hashtable<Integer,char[]>	codeTableHash(Character c) Performs a lookup of the MARC8 translation of a given Unicode character.
static char[]	deHexify(String str) Utility function for translating a String consisting of one or more two character hex string of the character values into a character array containing those characters
char	getBestCharSet(Character c) Lookups up the MARC8 translation of a given Unicode character and determines which of the MARC-8 character sets that have a translation for that Unicode character is the best one to use.
char[]	getCharEntry(Character c, int charset) Returns the MARC8 translation of a given Unicode character from the character set currently loaded as either the G0 or the G1 character set, as specified by the second parameter.
abstract Hashtable<Integer,char[]>	getCharTable(Character c) Abstract method that must be defined in a sub-class, used in the conversion of Unicode to MARC-8.
char[]	getCurrentG0CharEntry(Character c) Returns the MARC8 translation of a given Unicode character from the character set currently loaded as the G0 character set.
char[]	getCurrentG1CharEntry(Character c) Returns the MARC8 translation of a given Unicode character from the character set currently loaded as the G0 character set.
byte	getPreviousG0() Routine used for tracking which character set is currently in use for characters less than 0x80
byte	getPreviousG1() Routine used for tracking which character set is currently in use for characters greater than 0x80
void	init() Initializes the ReverseCodeTable state to the default value for encoding a field.
boolean	inPreviousG0CharEntry(Character c) Checks whether a MARC8 translation of a given Unicode character exists in the character set currently loaded as the G0 character set.
boolean	inPreviousG1CharEntry(Character c) Checks whether a MARC8 translation of a given Unicode character exists in the character set currently loaded as the G1 character set.
abstract boolean	isCombining(Character c) Abstract method that must be defined in a sub-class, used in the conversion of Unicode to MARC-8.
void	setPreviousG0(int table) Routine used for changing which character set is currently in use for characters less than 0x80
void	setPreviousG1(int table) Routine used for changing which character set is currently in use for characters greater than 0x80

Methods inherited from class java.lang.Object

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

Field Detail

lastLookupKey

protected Character lastLookupKey

lastLookupValue

protected Hashtable<Integer,char[]> lastLookupValue

g

protected byte[] g

charsetsUsed

protected String charsetsUsed

Constructor Detail

ReverseCodeTable

public ReverseCodeTable()

Default constructor for the abstract class, allocates and initializes the structures that are used to track the current character sets in use.

Method Detail

isCombining

public abstract boolean isCombining(Character c)

Abstract method that must be defined in a sub-class, used in the conversion of Unicode to MARC-8. For a given Unicode character, determine whether that character is a combining character (an accent mark or diacritic)

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if character is a combining character

getCharTable

public abstract Hashtable<Integer,char[]> getCharTable(Character c)

Abstract method that must be defined in a sub-class, used in the conversion of Unicode to MARC-8. For a given Unicode character, return ALL of the possible MARC-8 representations of that character. These are represented in a Hashtable where the key is the ISOcode of the character set in MARC-8 that the Unicode character appears in, and the value is the MARC-8 character value in that character set that encodes the given Unicode character.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

Hashtable - contains all of the possible MARC-8 representations of that Unicode character

init

public void init()

Initializes the ReverseCodeTable state to the default value for encoding a field.

getPreviousG0

public byte getPreviousG0()

Routine used for tracking which character set is currently in use for characters less than 0x80

Returns:

byte - the current G0 character set in use.

getPreviousG1

public byte getPreviousG1()

Routine used for tracking which character set is currently in use for characters greater than 0x80

Returns:

byte - the current G1 character set in use.

setPreviousG0

public void setPreviousG0(int table)

Routine used for changing which character set is currently in use for characters less than 0x80

Parameters:

table - - the current G0 character set to be used.

setPreviousG1

public void setPreviousG1(int table)

Routine used for changing which character set is currently in use for characters greater than 0x80

Parameters:

table - - the current G1 character set to be used.

codeTableHash

public Hashtable<Integer,char[]> codeTableHash(Character c)

Performs a lookup of the MARC8 translation of a given Unicode character. Caches the results in lastLookupKey and lastLookupValue so that subsequent lookups made in processing the same character will proceed more quickly.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

Hashtable - contains all of the possible MARC-8 representations of that Unicode character

charHasMatch

public boolean charHasMatch(Character c)

Checks whether a MARC8 translation of a given Unicode character exists.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if there is one or more MARC-8 representation of the given Unicode character.

inPreviousG0CharEntry

public boolean inPreviousG0CharEntry(Character c)

Checks whether a MARC8 translation of a given Unicode character exists in the character set currently loaded as the G0 character set.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if there is a MARC-8 representation of the given Unicode character in the current G0 character set

inPreviousG1CharEntry

public boolean inPreviousG1CharEntry(Character c)

Checks whether a MARC8 translation of a given Unicode character exists in the character set currently loaded as the G1 character set.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if there is a MARC-8 representation of the given Unicode character in the current G1 character set

getCurrentG0CharEntry

public char[] getCurrentG0CharEntry(Character c)

Returns the MARC8 translation of a given Unicode character from the character set currently loaded as the G0 character set.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if there is a MARC-8 representation of the given Unicode character in the current G0 character set

getCurrentG1CharEntry

public char[] getCurrentG1CharEntry(Character c)

Returns the MARC8 translation of a given Unicode character from the character set currently loaded as the G0 character set.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if there is a MARC-8 representation of the given Unicode character in the current G0 character set

getCharEntry

public char[] getCharEntry(Character c,
                  int charset)

Returns the MARC8 translation of a given Unicode character from the character set currently loaded as either the G0 or the G1 character set, as specified by the second parameter.

Parameters:

c - - the UCS/Unicode character to look up

charset - - whether to use the current G0 charset of the current G1 charset to perform the lookup

Returns:

boolean - true if there is a MARC-8 representation of the given Unicode character in the current G0 character set

getBestCharSet

public char getBestCharSet(Character c)

Lookups up the MARC8 translation of a given Unicode character and determines which of the MARC-8 character sets that have a translation for that Unicode character is the best one to use. If one one charset has a translation, that one will be returned. If more than one charset has a translation then return the first one listed.

Parameters:

c - - the UCS/Unicode character to look up

Returns:

boolean - true if there is a MARC-8 representation of the given Unicode character in the current G0 character set

deHexify

public static char[] deHexify(String str)

Utility function for translating a String consisting of one or more two character hex string of the character values into a character array containing those characters

Parameters:

str - - A string containing the two-character hex strings of characters to decode

Returns:

char[] - an array of characters represented by the