Package com.ibm.icu.text

Class UnicodeSetSpanner

java.lang.Object

com.ibm.icu.text.UnicodeSetSpanner

public class UnicodeSetSpanner
extends Object

A helper class used to count, replace, and trim CharSequences based on UnicodeSet matches. An instance is immutable (and thus thread-safe) iff the source UnicodeSet is frozen.

Note: The counting, deletion, and replacement depend on alternating a UnicodeSet.SpanCondition with its inverse. That is, the code spans, then spans for the inverse, then spans, and so on. For the inverse, the following mapping is used:

• UnicodeSet.SpanCondition.SIMPLE → UnicodeSet.SpanCondition.NOT_CONTAINED
• UnicodeSet.SpanCondition.CONTAINED → UnicodeSet.SpanCondition.NOT_CONTAINED
• UnicodeSet.SpanCondition.NOT_CONTAINED → UnicodeSet.SpanCondition.SIMPLE

These are actually not complete inverses. However, the alternating works because there are no gaps. For example, with [a{ab}{bc}], you get the following behavior when scanning forward:

SIMPLE	xxx[ab]cyyy
CONTAINED	xxx[abc]yyy
NOT_CONTAINED	[xxx]ab[cyyy]

So here is what happens when you alternate:

start	|xxxabcyyy
NOT_CONTAINED	xxx|abcyyy
CONTAINED	xxxabc|yyy
NOT_CONTAINED	xxxabcyyy|

The entire string is traversed.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	UnicodeSetSpanner.CountMethod	Options for replaceFrom and countIn to control how to treat each matched span.
static class	UnicodeSetSpanner.TrimOption	Options for the trim() method

Constructor Summary

Constructors

Constructor	Description
UnicodeSetSpanner(UnicodeSet source)	Create a spanner from a UnicodeSet.

Method Summary

Modifier and Type	Method	Description
int	countIn(CharSequence sequence)	Returns the number of matching characters found in a character sequence, counting by CountMethod.MIN_ELEMENTS using SpanCondition.SIMPLE.
int	countIn(CharSequence sequence, UnicodeSetSpanner.CountMethod countMethod)	Returns the number of matching characters found in a character sequence, using SpanCondition.SIMPLE.
int	countIn(CharSequence sequence, UnicodeSetSpanner.CountMethod countMethod, UnicodeSet.SpanCondition spanCondition)	Returns the number of matching characters found in a character sequence.
String	deleteFrom(CharSequence sequence)	Delete all the matching spans in sequence, using SpanCondition.SIMPLE The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.
String	deleteFrom(CharSequence sequence, UnicodeSet.SpanCondition spanCondition)	Delete all matching spans in sequence, according to the spanCondition.
boolean	equals(Object other)	Compares this instance with the specified object and indicates if they are equal.
UnicodeSet	getUnicodeSet()	Returns the UnicodeSet used for processing.
int	hashCode()	Returns an integer hash code for this object.
String	replaceFrom(CharSequence sequence, CharSequence replacement)	Replace all matching spans in sequence by the replacement, counting by CountMethod.MIN_ELEMENTS using SpanCondition.SIMPLE.
String	replaceFrom(CharSequence sequence, CharSequence replacement, UnicodeSetSpanner.CountMethod countMethod)	Replace all matching spans in sequence by replacement, according to the CountMethod, using SpanCondition.SIMPLE.
String	replaceFrom(CharSequence sequence, CharSequence replacement, UnicodeSetSpanner.CountMethod countMethod, UnicodeSet.SpanCondition spanCondition)	Replace all matching spans in sequence by replacement, according to the countMethod and spanCondition.
CharSequence	trim(CharSequence sequence)	Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start and end of the string, using TrimOption.BOTH and SpanCondition.SIMPLE.
CharSequence	trim(CharSequence sequence, UnicodeSetSpanner.TrimOption trimOption)	Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start or end of the string, using the trimOption and SpanCondition.SIMPLE.
CharSequence	trim(CharSequence sequence, UnicodeSetSpanner.TrimOption trimOption, UnicodeSet.SpanCondition spanCondition)	Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start or end of the string, depending on the trimOption and spanCondition.

Methods inherited from class java.lang.Object

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

Constructor Detail

UnicodeSetSpanner

public UnicodeSetSpanner(UnicodeSet source)

Create a spanner from a UnicodeSet. For speed and safety, the UnicodeSet should be frozen. However, this class can be used with a non-frozen version to avoid the cost of freezing.

Parameters:

source - the original UnicodeSet

Method Detail

getUnicodeSet

public UnicodeSet getUnicodeSet()

Returns the UnicodeSet used for processing. It is frozen iff the original was.

Returns:

the construction set.

equals

public boolean equals(Object other)

Compares this instance with the specified object and indicates if they are equal. In order to be equal, o must represent the same object as this instance using a class-specific comparison. The general contract is that this comparison should be reflexive, symmetric, and transitive. Also, no object reference other than null is equal to null.

The default implementation returns true only if this == o. See Writing a correct equals method if you intend implementing your own equals method.

The general contract for the equals and Object.hashCode() methods is that if equals returns true for any two objects, then hashCode() must return the same value for these objects. This means that subclasses of Object usually override either both methods or neither of them.

Overrides:

equals in class Object

Parameters:

other - the object to compare this instance with.

Returns:

true if the specified object is equal to this Object; false otherwise.

See Also:

Object.hashCode()

hashCode

public int hashCode()

Returns an integer hash code for this object. By contract, any two objects for which Object.equals(java.lang.Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

Note that hash values must not change over time unless information used in equals comparisons also changes.

See Writing a correct hashCode method if you intend implementing your own hashCode method.

Overrides:

hashCode in class Object

Returns:

this object's hash code.

See Also:

Object.equals(java.lang.Object)

countIn

public int countIn(CharSequence sequence)

Returns the number of matching characters found in a character sequence, counting by CountMethod.MIN_ELEMENTS using SpanCondition.SIMPLE. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - the sequence to count characters in

Returns:

the count. Zero if there are none.

countIn

public int countIn(CharSequence sequence,
                   UnicodeSetSpanner.CountMethod countMethod)

Returns the number of matching characters found in a character sequence, using SpanCondition.SIMPLE. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - the sequence to count characters in

countMethod - whether to treat an entire span as a match, or individual elements as matches

Returns:

the count. Zero if there are none.

countIn

public int countIn(CharSequence sequence,
                   UnicodeSetSpanner.CountMethod countMethod,
                   UnicodeSet.SpanCondition spanCondition)

Returns the number of matching characters found in a character sequence. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - the sequence to count characters in

countMethod - whether to treat an entire span as a match, or individual elements as matches

spanCondition - the spanCondition to use. SIMPLE or CONTAINED means only count the elements in the span; NOT_CONTAINED is the reverse.
WARNING: when a UnicodeSet contains strings, there may be unexpected behavior in edge cases.

Returns:

the count. Zero if there are none.

deleteFrom

public String deleteFrom(CharSequence sequence)

Delete all the matching spans in sequence, using SpanCondition.SIMPLE The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - charsequence to replace matching spans in.

Returns:

modified string.

deleteFrom

public String deleteFrom(CharSequence sequence,
                         UnicodeSet.SpanCondition spanCondition)

Delete all matching spans in sequence, according to the spanCondition. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - charsequence to replace matching spans in.

spanCondition - specify whether to modify the matching spans (CONTAINED or SIMPLE) or the non-matching (NOT_CONTAINED)

Returns:

modified string.

replaceFrom

public String replaceFrom(CharSequence sequence,
                          CharSequence replacement)

Replace all matching spans in sequence by the replacement, counting by CountMethod.MIN_ELEMENTS using SpanCondition.SIMPLE. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - charsequence to replace matching spans in.

replacement - replacement sequence. To delete, use ""

Returns:

modified string.

replaceFrom

public String replaceFrom(CharSequence sequence,
                          CharSequence replacement,
                          UnicodeSetSpanner.CountMethod countMethod)

Replace all matching spans in sequence by replacement, according to the CountMethod, using SpanCondition.SIMPLE. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - charsequence to replace matching spans in.

replacement - replacement sequence. To delete, use ""

countMethod - whether to treat an entire span as a match, or individual elements as matches

Returns:

modified string.

replaceFrom

public String replaceFrom(CharSequence sequence,
                          CharSequence replacement,
                          UnicodeSetSpanner.CountMethod countMethod,
                          UnicodeSet.SpanCondition spanCondition)

Replace all matching spans in sequence by replacement, according to the countMethod and spanCondition. The code alternates spans; see the class doc for UnicodeSetSpanner for a note about boundary conditions.

Parameters:

sequence - charsequence to replace matching spans in.

replacement - replacement sequence. To delete, use ""

countMethod - whether to treat an entire span as a match, or individual elements as matches

spanCondition - specify whether to modify the matching spans (CONTAINED or SIMPLE) or the non-matching (NOT_CONTAINED)

Returns:

modified string.

trim

public CharSequence trim(CharSequence sequence)

Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start and end of the string, using TrimOption.BOTH and SpanCondition.SIMPLE. For example:

 
 
   new UnicodeSet("[ab]").trim("abacatbab")
 

... returns "cat".

Parameters:

sequence - the sequence to trim

Returns:

a subsequence

trim

public CharSequence trim(CharSequence sequence,
                         UnicodeSetSpanner.TrimOption trimOption)

Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start or end of the string, using the trimOption and SpanCondition.SIMPLE. For example:

 
 
   new UnicodeSet("[ab]").trim("abacatbab", TrimOption.LEADING)
 

... returns "catbab".

Parameters:

sequence - the sequence to trim

trimOption - LEADING, TRAILING, or BOTH

Returns:

a subsequence

trim

public CharSequence trim(CharSequence sequence,
                         UnicodeSetSpanner.TrimOption trimOption,
                         UnicodeSet.SpanCondition spanCondition)

Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start or end of the string, depending on the trimOption and spanCondition. For example:

 
 
   new UnicodeSet("[ab]").trim("abacatbab", TrimOption.LEADING, SpanCondition.SIMPLE)
 

... returns "catbab".

Parameters:

sequence - the sequence to trim

trimOption - LEADING, TRAILING, or BOTH

spanCondition - SIMPLE, CONTAINED or NOT_CONTAINED

Returns:

a subsequence