org.directwebremoting.impl
Class LegacyCompressor

java.lang.Object
  org.directwebremoting.impl.LegacyCompressor

All Implemented Interfaces:

Compressor

public class LegacyCompressor
extends java.lang.Object
implements Compressor

An implementation of Compressor that does nothing.

Author:

Joe Walker [joe at getahead dot ltd dot uk]

Field Summary

static int	COMPRESS_REMOVE_NEWLINES Flag for use in javascript compression: Remove all lines endings.
static int	COMPRESS_SHRINK_VARS Flag for use in javascript compression: Shrink variable names.
static int	COMPRESS_STRIP_BLANKLINES Flag for use in javascript compression: Remove blank lines.
static int	COMPRESS_STRIP_ML_COMMENTS Flag for use in javascript compression: Remove multi line comments.
static int	COMPRESS_STRIP_SL_COMMENTS Flag for use in javascript compression: Remove single line comments.
static int	COMPRESS_TRIM_LINES Flag for use in javascript compression: Remove whitespace at the start and end of a line.
static int	LEVEL_DEBUGGABLE Basic compression that leaves the source fully debuggable.
static int	LEVEL_NONE Compression level that leaves the source un-touched.
static int	LEVEL_NORMAL Normal compression makes all changes that will work for generic javascript.
static int	LEVEL_ULTRA LEVEL_ULTRA performs additional compression that makes some assumptions about the style of javascript.

Constructor Summary

LegacyCompressor()

Method Summary

static java.lang.String	compress(java.lang.String text, int level) Compress the source code by removing java style comments and removing leading and trailing spaces.
java.lang.String	compressJavaScript(java.lang.String script) Compress a JavaScript file to a smaller version of the original
void	setCompressionLevel(int compressionLevel)
static java.lang.String	shrinkVariableNames(java.lang.String text) Shrink variable names to a minimum.
static java.lang.String	stripBlankLines(java.lang.String text) Remove all blank lines from a string.
static java.lang.String	stripMultiLineComments(java.lang.String text) Remove all the multi-line comments from a block of text
static java.lang.String	stripNewlines(java.lang.String text) Remove all newline characters from a string.
static java.lang.String	stripSingleLineComments(java.lang.String text) Remove all the single-line comments from a block of text
static java.lang.String	trimLines(java.lang.String text) Remove any leading or trailing spaces from a line of code.

Methods inherited from class java.lang.Object

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

Field Detail

COMPRESS_STRIP_SL_COMMENTS

public static final int COMPRESS_STRIP_SL_COMMENTS

Flag for use in javascript compression: Remove single line comments. For ease of use you may wish to use one of the LEVEL_* compression levels.

See Also:

Constant Field Values

COMPRESS_STRIP_ML_COMMENTS

public static final int COMPRESS_STRIP_ML_COMMENTS

Flag for use in javascript compression: Remove multi line comments. For ease of use you may wish to use one of the LEVEL_* compression levels.

See Also:

Constant Field Values

COMPRESS_TRIM_LINES

public static final int COMPRESS_TRIM_LINES

Flag for use in javascript compression: Remove whitespace at the start and end of a line. For ease of use you may wish to use one of the LEVEL_* compression levels.

See Also:

Constant Field Values

COMPRESS_STRIP_BLANKLINES

public static final int COMPRESS_STRIP_BLANKLINES

Flag for use in javascript compression: Remove blank lines. This option will make the javascript harder to debug because line number references are likely be altered. For ease of use you may wish to use one of the LEVEL_* compression levels.

See Also:

Constant Field Values

COMPRESS_SHRINK_VARS

public static final int COMPRESS_SHRINK_VARS

Flag for use in javascript compression: Shrink variable names. This option is currently un-implemented. For ease of use you may wish to use one of the LEVEL_* compression levels.

See Also:

Constant Field Values

COMPRESS_REMOVE_NEWLINES

public static final int COMPRESS_REMOVE_NEWLINES

Flag for use in javascript compression: Remove all lines endings. Warning: Javascript can add semi-colons in for you. If you make use of this feature then removing newlines may well break. For ease of use you may wish to use one of the LEVEL_* compression levels.

See Also:

Constant Field Values

LEVEL_NONE

public static final int LEVEL_NONE

Compression level that leaves the source un-touched.

See Also:

Constant Field Values

LEVEL_DEBUGGABLE

public static final int LEVEL_DEBUGGABLE

Basic compression that leaves the source fully debuggable. This includes removing all comments and extraneous whitespace.

See Also:

Constant Field Values

LEVEL_NORMAL

public static final int LEVEL_NORMAL

Normal compression makes all changes that will work for generic javascript. This adds variable name compression and blank line removal in addition to the compressions done by LEVEL_DEBUGGABLE.

See Also:

Constant Field Values

LEVEL_ULTRA

public static final int LEVEL_ULTRA

LEVEL_ULTRA performs additional compression that makes some assumptions about the style of javascript. Specifically it assumes that you are not using JavaScript's ability to infer where the ; should go.

See Also:

Constant Field Values

Constructor Detail

LegacyCompressor

public LegacyCompressor()

Method Detail

compressJavaScript

public java.lang.String compressJavaScript(java.lang.String script)
                                    throws java.io.IOException

Description copied from interface: Compressor

Compress a JavaScript file to a smaller version of the original

Specified by:

compressJavaScript in interface Compressor

Parameters:

script - The script to compress

Returns:

The compressed script

Throws:

java.io.IOException

compress

public static java.lang.String compress(java.lang.String text,
                                        int level)

Compress the source code by removing java style comments and removing leading and trailing spaces.

Parameters:

text - The javascript (or java) program to compress

level - The compression level - see LEVEL_* and COMPRESS_* constants.

Returns:

The compressed version

trimLines

public static java.lang.String trimLines(java.lang.String text)

Remove any leading or trailing spaces from a line of code. This function could be improved by making it strip unnecessary double spaces, but since we would need to leave double spaces inside strings this is not simple and since the benefit is small, we'll leave it for now

Parameters:

text - The javascript program to strip spaces from.

Returns:

The stripped program

stripSingleLineComments

public static java.lang.String stripSingleLineComments(java.lang.String text)

Remove all the single-line comments from a block of text

Parameters:

text - The text to remove single-line comments from

Returns:

The single-line comment free text

stripMultiLineComments

public static java.lang.String stripMultiLineComments(java.lang.String text)

Remove all the multi-line comments from a block of text

Parameters:

text - The text to remove multi-line comments from

Returns:

The multi-line comment free text

stripBlankLines

public static java.lang.String stripBlankLines(java.lang.String text)

Remove all blank lines from a string. A blank line is defined to be a line where the only characters are whitespace. We always ensure that the line contains a newline at the end.

Parameters:

text - The string to strip blank lines from

Returns:

The blank line stripped reply

stripNewlines

public static java.lang.String stripNewlines(java.lang.String text)

Remove all newline characters from a string.

Parameters:

text - The string to strip newline characters from

Returns:

The stripped reply

shrinkVariableNames

public static java.lang.String shrinkVariableNames(java.lang.String text)

Shrink variable names to a minimum.

Parameters:

text - The javascript program to shrink the variable names in.

Returns:

The shrunk version of the javascript program.

setCompressionLevel

public void setCompressionLevel(int compressionLevel)

Parameters:

compressionLevel - The compressionLevel to set.