squidpony

Class LZSEncoding

java.lang.Object

squidpony.LZSEncoding

public final class LZSEncoding
extends java.lang.Object

LZ-String compression; wrapped by LZSPlus for convenience, but extended functionality is available here. You can compress a String to a smaller, technically-invalid UTF-16 String with compress(String), and undo that with decompress(String). Compress to a valid UTF-16 String with compressToUTF16(String), decompress such a String with decompressFromUTF16(String) (LZSPlus uses these). Compress to Base64 with compressToBase64(String), decompress Base64 with decompressFromBase64(String). Compress to URI-encoded Strings with compressToEncodedURIComponent(String), decompress those with decompressFromEncodedURIComponent(String). This class is super-sourced with a compatible alternative implementation on GWT for performance, and a main goal is to provide UTF-16 Strings that can be stored in a browser's LocalStorage on GWT. This class is also sometimes used internally when a large compressed String in Java source code makes more sense than an even larger resource file.

Method Summary

Modifier and Type	Method and Description
static java.lang.String	compress(java.lang.String uncompressed) Compresses a String as tightly as possible by using 16 bits of each 16-bit character, which can infrequently result in invalid UTF-16 codepoints, but that may not matter for all applications.
static java.lang.String	compressToBase64(java.lang.String uncompressed) Compress a String using LZ-String encoding but only using Base64 characters ('A'-'Z', 'a'-'z', '0'-'9', '+', '/', and '=' for Base64 validity).
static java.lang.String	compressToEncodedURIComponent(java.lang.String uncompressed) Compress a String using LZ-String encoding but only using valid URI component characters ('A'-'Z', 'a'-'z', '0'-'9', '+', '-', and possibly '$').
static java.lang.String	compressToUTF16(java.lang.String uncompressed) Compresses a String using the properties of UTF-16 encoding to store approximately 15 bits of LZW-compressed text in each 2-byte Unicode character, which does particularly well with ASCII text and can be smaller than UTF-8 in some cases, especially where each char must be stored as UTF-16, e.g.
static java.lang.String	decompress(java.lang.String compressed) Decompresses a String that had been compressed with compress(String).
static java.lang.String	decompressFromBase64(java.lang.String compressed) Decompresses a String that had been compressed with compressToBase64(String).
static java.lang.String	decompressFromEncodedURIComponent(java.lang.String compressed) Decompresses a String that had been compressed with compressToEncodedURIComponent(String).
static java.lang.String	decompressFromUTF16(java.lang.String compressed) Decompresses a String that had been compressed with compressToUTF16(String).

Methods inherited from class java.lang.Object

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

Method Detail

compressToBase64

public static java.lang.String compressToBase64(java.lang.String uncompressed)

Compress a String using LZ-String encoding but only using Base64 characters ('A'-'Z', 'a'-'z', '0'-'9', '+', '/', and '=' for Base64 validity).

Parameters:

uncompressed - an uncompressed String to encode

Returns:

the encoded, compressed String

decompressFromBase64

public static java.lang.String decompressFromBase64(java.lang.String compressed)

Decompresses a String that had been compressed with compressToBase64(String).

Parameters:

compressed - a Base64-encoded, compressed String

Returns:

the original uncompressed version of the String

compressToUTF16

public static java.lang.String compressToUTF16(java.lang.String uncompressed)

Compresses a String using the properties of UTF-16 encoding to store approximately 15 bits of LZW-compressed text in each 2-byte Unicode character, which does particularly well with ASCII text and can be smaller than UTF-8 in some cases, especially where each char must be stored as UTF-16, e.g. Java Strings or browser-based LocalStorage.

Parameters:

uncompressed - an uncompressed String to encode

Returns:

the encoded, compressed String

decompressFromUTF16

public static java.lang.String decompressFromUTF16(java.lang.String compressed)

Decompresses a String that had been compressed with compressToUTF16(String).

Parameters:

compressed - a UTF16-encoded (as by compressToUTF16(String)), compressed String

Returns:

the original uncompressed version of the String

compressToEncodedURIComponent

public static java.lang.String compressToEncodedURIComponent(java.lang.String uncompressed)

Compress a String using LZ-String encoding but only using valid URI component characters ('A'-'Z', 'a'-'z', '0'-'9', '+', '-', and possibly '$').

Parameters:

uncompressed - an uncompressed String to encode

Returns:

the encoded, compressed String

decompressFromEncodedURIComponent

public static java.lang.String decompressFromEncodedURIComponent(java.lang.String compressed)

Decompresses a String that had been compressed with compressToEncodedURIComponent(String).

Parameters:

compressed - a URI-encoded, compressed String

Returns:

the original uncompressed version of the String

compress

public static java.lang.String compress(java.lang.String uncompressed)

Compresses a String as tightly as possible by using 16 bits of each 16-bit character, which can infrequently result in invalid UTF-16 codepoints, but that may not matter for all applications.

Parameters:

uncompressed - an uncompressed String to encode

Returns:

the encoded, compressed String

decompress

public static java.lang.String decompress(java.lang.String compressed)

Decompresses a String that had been compressed with compress(String).

Parameters:

compressed - a compressed String using the default encoding from compress(String)

Returns:

the original uncompressed version of the String