facets.util
Class StringFlags

java.lang.Object
  facets.util.StringFlags

All Implemented Interfaces:

java.io.Serializable

public final class StringFlags
extends java.lang.Object
implements java.io.Serializable

Container for flags defined using strings.

StringFlags offers an alternative to int constants to encode flags, being

• type-safe - no chance of confusion with ints used as values
• equally compact to code
• more intuitive - no need to combine by ORing and decode by ANDing
• infinitely extensible - not limited by bit space available
• largely self-documenting - the type name says it all, no need to reserve identifiers such as 'flags', 'type' etc.
• object-oriented - in the useful sense that the type itself provides all the support need to code it, not relying like ints on externally defined logical arcana.
• easier to debug - values are human-readable

StringFlags defines flags as set or reset by the presence or absence in its (immutable) contained string of string constants which should be created with newFlag(String). Collisions between partial or complete flag strings are avoided by prefixing each with the PREFIX constant and by numbering flags sequentially.

See Also:

Serialized Form

Field Summary

static StringFlags	EMPTY
static java.lang.String	FLAG_NONE
static java.lang.String	PREFIX

Constructor Summary

StringFlags(java.lang.String flags)
Unique constructor.

Method Summary

StringFlags	addFlag(java.lang.String flag) Add a flag.
boolean	includeFlag(java.lang.String flag) Do the flags set include this flagged string?
static java.lang.String	newFlag(java.lang.String text) Converts text into an appropriate flag.
StringFlags	removeFlag(java.lang.String flag) Remove a flag.
java.lang.String	toString() Lists the current set of flags.

Methods inherited from class java.lang.Object

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

Field Detail

PREFIX

public static final java.lang.String PREFIX

See Also:

Constant Field Values

FLAG_NONE

public static final java.lang.String FLAG_NONE

EMPTY

public static final StringFlags EMPTY

Constructor Detail

StringFlags

public StringFlags(java.lang.String flags)

Unique constructor.

Parameters:

flags - must a concatenation of strings created using newFlag(String).

Method Detail

newFlag

public static final java.lang.String newFlag(java.lang.String text)

Converts text into an appropriate flag.

The flag is guaranteed to be acceptable when passed to the constructor either on its own or concatenated with others created by this method. Such flags are therefore suitable as constants for use by application code.

Parameters:

text - may be any string not including the PREFIX constant beyond its start and will define a single flag

includeFlag

public boolean includeFlag(java.lang.String flag)

Do the flags set include this flagged string?

Parameters:

flag - must have been created with newFlag(String).

addFlag

public StringFlags addFlag(java.lang.String flag)

Add a flag.

Parameters:

flag - must have been created with newFlag(String).

Returns:

a StringFlags with flag appended to the flags if not already included

removeFlag

public StringFlags removeFlag(java.lang.String flag)

Remove a flag.

Parameters:

flag - must have been created with newFlag(String).

Returns:

a StringFlags with flag absent from the flags

toString

public java.lang.String toString()

Lists the current set of flags.

Overrides:

toString in class java.lang.Object