org.apache.oro.text.regex
Class Util
java.lang.Object
org.apache.oro.text.regex.Util
public final class Util
extends java.lang.Object
The Util class is a holder for useful static utility methods that can
be generically applied to Pattern and PatternMatcher instances.
This class cannot and is not meant to be instantiated.
The Util class currently contains versions of the split() and substitute()
methods inspired by Perl's split function and
s operation
respectively, although they are implemented in such a way as not to
rely on the Perl5 implementations of the OROMatcher packages regular
expression interfaces. They may operate on any interface implementations
conforming to the OROMatcher API specification for the PatternMatcher,
Pattern, and MatchResult interfaces. Future versions of the class may
include additional utility methods.
A grep method is not included for two reasons:
- The details of reading a line at a time from an input stream
differ in JDK 1.0.2 and JDK 1.1, making it difficult to
retain compatibility across both Java releases.
- Grep style processing is trivial for the programmer to implement
in a while loop. Rarely does anyone want to retrieve all
occurences of a pattern and then process them. More often a
programmer will retrieve pattern matches and process them as they
are retrieved, which is more efficient than storing them all in a
Vector and then accessing them.
Version:
- 1.0
Pattern
, PatternMatcher
static int | SPLIT_ALL - A constant passed to the
split() methods
indicating that all occurrences of a pattern should be used to
split a string.
|
static int | SUBSTITUTE_ALL - A constant passed to the
substitute()
methods indicating that all occurrences of a pattern should be
substituted.
|
static void | split(Collection results, PatternMatcher matcher, Pattern pattern, String input) - Splits up a
String instance and stores results as a
Collection of all its substrings using a regular expression
as the delimiter.
|
static void | split(Collection results, PatternMatcher matcher, Pattern pattern, String input, int limit) - Splits up a
String instance and stores results as a
List of substrings numbering no more than a specified
limit.
|
static Vector | split(PatternMatcher matcher, Pattern pattern, String input) - Use
|
static Vector | split(PatternMatcher matcher, Pattern pattern, String input, int limit) - Use
|
static int | substitute(StringBuffer result, PatternMatcher matcher, Pattern pattern, Substitution sub, String input, int numSubs) - Searches a string for a pattern and replaces the first occurrences
of the pattern with a Substitution up to the number of
substitutions specified by the numSubs parameter.
|
static int | substitute(StringBuffer result, PatternMatcher matcher, Pattern pattern, Substitution sub, PatternMatcherInput input, int numSubs) - Searches a string for a pattern and replaces the first occurrences
of the pattern with a Substitution up to the number of
substitutions specified by the numSubs parameter.
|
static String | substitute(PatternMatcher matcher, Pattern pattern, Substitution sub, String input) - Searches a string for a pattern and substitutes only the first
occurence of the pattern.
|
static String | substitute(PatternMatcher matcher, Pattern pattern, Substitution sub, String input, int numSubs) - Searches a string for a pattern and replaces the first occurrences
of the pattern with a Substitution up to the number of
substitutions specified by the numSubs parameter.
|
SPLIT_ALL
public static final int SPLIT_ALL
A constant passed to the split()
methods
indicating that all occurrences of a pattern should be used to
split a string.
- 0
SUBSTITUTE_ALL
public static final int SUBSTITUTE_ALL
A constant passed to the substitute()
methods indicating that all occurrences of a pattern should be
substituted.
- -1
split
public static void split(Collection results,
PatternMatcher matcher,
Pattern pattern,
String input)
Splits up a
String
instance and stores results as a
Collection
of all its substrings using a regular expression
as the delimiter.
This method is inspired by the Perl split() function and behaves
identically to it when used in conjunction with the Perl5Matcher and
Perl5Pattern classes except for the following difference:
In Perl, if the split expression contains parentheses, the split()
method creates additional list elements from each of the matching
subgroups in the pattern. In other words:
split(list, "/([,-])/", "8-12,15,18")
produces the list containing:
{ "8", "-", "12", ",", "15", ",", "18" }
The OROMatcher split method does not follow this behavior. The
following list would be produced by OROMatcher:
{ "8", "12", "15", "18" }
To obtain the Perl behavior, use
org.apache.oro.text.perl.Perl5Util.split
.
This method is identical to calling:
split(matcher, pattern, input, Util.SPLIT_ALL);
results
- A Collection
to which all the substrings of
the input that occur between the regular expression delimiter
occurences are appended.matcher
- The regular expression matcher to execute the split.pattern
- The regular expression to use as a split delimiter.input
- The String
to split.
- 2.0
split
public static void split(Collection results,
PatternMatcher matcher,
Pattern pattern,
String input,
int limit)
Splits up a
String
instance and stores results as a
List
of substrings numbering no more than a specified
limit. The string is split with a regular expression as the delimiter.
The
limit parameter essentially says to split the
string only on at most the first
limit - 1 number of pattern
occurences.
This method is inspired by the Perl split() function and behaves
identically to it when used in conjunction with the Perl5Matcher and
Perl5Pattern classes except for the following difference:
In Perl, if the split expression contains parentheses, the split()
method creates additional list elements from each of the matching
subgroups in the pattern. In other words:
split(list, "/([,-])/", "8-12,15,18", Util.SPLIT_ALL)
produces the list containing:
{ "8", "-", "12", ",", "15", ",", "18" }
The OROMatcher split method does not follow this behavior. The
following list would be produced by OROMatcher:
{ "8", "12", "15", "18" }
To obtain the Perl behavior, use
org.apache.oro.text.perl.Perl5Util.split
.
results
- A Collection to which the split results are appended.
After the method returns, it contains the substrings of the input
that occur between the regular expression delimiter occurences.
The input will not be split into any more substrings than the
specified limit
. A way of thinking of this is that
only the first limit - 1
matches of the delimiting
regular expression will be used to split the input.matcher
- The regular expression matcher to execute the split.pattern
- The regular expression to use as a split delimiter.input
- The String
to split.limit
- The limit on the number of resulting split elements.
Values <= 0 produce the same behavior as using the
SPLIT_ALL constant which causes the limit to be
ignored and splits to be performed on all occurrences of
the pattern. You should use the SPLIT_ALL constant
to achieve this behavior instead of relying on the default
behavior associated with non-positive limit values.
- 2.0
split
public static Vector split(PatternMatcher matcher,
Pattern pattern,
String input)
Use
Splits up a
String
instance into a
Vector
of all its substrings using a regular expression as the delimiter.
This method is inspired by the Perl split() function and behaves
identically to it when used in conjunction with the Perl5Matcher and
Perl5Pattern classes except for the following difference:
In Perl, if the split expression contains parentheses, the split()
method creates additional list elements from each of the matching
subgroups in the pattern. In other words:
split("/([,-])/", "8-12,15,18")
produces the Vector containing:
{ "8", "-", "12", ",", "15", ",", "18" }
The OROMatcher split method does not follow this behavior. The
following Vector would be produced by OROMatcher:
{ "8", "12", "15", "18" }
To obtain the Perl behavior, use
org.apache.oro.text.perl.Perl5Util.split
.
This method is identical to calling:
split(matcher, pattern, input, Util.SPLIT_ALL);
split(Collection,PatternMatcher,Pattern,String)
instead.
matcher
- The regular expression matcher to execute the split.pattern
- The regular expression to use as a split delimiter.input
- The String
to split.
- A
Vector
containing all the substrings of the input
that occur between the regular expression delimiter occurences.
- 1.0
split
public static Vector split(PatternMatcher matcher,
Pattern pattern,
String input,
int limit)
Use
Splits up a
String
instance into strings contained in a
Vector
of size not greater than a specified limit. The
string is split with a regular expression as the delimiter.
The
limit parameter essentially says to split the
string only on at most the first
limit - 1 number of pattern
occurences.
This method is inspired by the Perl split() function and behaves
identically to it when used in conjunction with the Perl5Matcher and
Perl5Pattern classes except for the following difference:
In Perl, if the split expression contains parentheses, the split()
method creates additional list elements from each of the matching
subgroups in the pattern. In other words:
split("/([,-])/", "8-12,15,18")
produces the Vector containing:
{ "8", "-", "12", ",", "15", ",", "18" }
The OROMatcher split method does not follow this behavior. The
following Vector would be produced by OROMatcher:
{ "8", "12", "15", "18" }
To obtain the Perl behavior, use
org.apache.oro.text.perl.Perl5Util.split
.
split(Collection,PatternMatcher,Pattern,String,int)
instead.
matcher
- The regular expression matcher to execute the split.pattern
- The regular expression to use as a split delimiter.input
- The String
to split.limit
- The limit on the size of the returned Vector
.
Values <= 0 produce the same behavior as using the
SPLIT_ALL constant which causes the limit to be
ignored and splits to be performed on all occurrences of
the pattern. You should use the SPLIT_ALL constant
to achieve this behavior instead of relying on the default
behavior associated with non-positive limit values.
- A
Vector
containing the substrings of the input
that occur between the regular expression delimiter occurences.
The input will not be split into any more substrings than the
specified limit
. A way of thinking of this is that
only the first limit - 1
matches of the delimiting
regular expression will be used to split the input.
- 1.0
substitute
public static int substitute(StringBuffer result,
PatternMatcher matcher,
Pattern pattern,
Substitution sub,
String input,
int numSubs)
Searches a string for a pattern and replaces the first occurrences
of the pattern with a Substitution up to the number of
substitutions specified by the
numSubs parameter. A
numSubs value of
SUBSTITUTE_ALL will cause all occurrences
of the pattern to be replaced. The number of substitutions made
is returned.
result
- The StringBuffer in which to store the result of the
substitutions. The buffer is only appended to.matcher
- The regular expression matcher to execute the pattern
search.pattern
- The regular expression to search for and substitute
occurrences of.sub
- The Substitution used to substitute pattern occurences.input
- The input on which to perform substitutions.numSubs
- The number of substitutions to perform. Only the
first numSubs patterns encountered are
substituted. If you want to substitute all occurences
set this parameter to SUBSTITUTE_ALL .
- The number of substitutions made.
- 2.0.6
substitute
public static int substitute(StringBuffer result,
PatternMatcher matcher,
Pattern pattern,
Substitution sub,
PatternMatcherInput input,
int numSubs)
Searches a string for a pattern and replaces the first occurrences
of the pattern with a Substitution up to the number of
substitutions specified by the
numSubs parameter. A
numSubs value of
SUBSTITUTE_ALL will cause all occurrences
of the pattern to be replaced. The number of substitutions made
is returned.
result
- The StringBuffer in which to store the result of the
substitutions. The buffer is only appended to.matcher
- The regular expression matcher to execute the pattern
search.pattern
- The regular expression to search for and substitute
occurrences of.sub
- The Substitution used to substitute pattern occurences.input
- The input on which to perform substitutions.numSubs
- The number of substitutions to perform. Only the
first numSubs patterns encountered are
substituted. If you want to substitute all occurences
set this parameter to SUBSTITUTE_ALL .
- The number of substitutions made.
- 2.0.3
substitute
public static String substitute(PatternMatcher matcher,
Pattern pattern,
Substitution sub,
String input)
Searches a string for a pattern and substitutes only the first
occurence of the pattern.
This method is identical to calling:
substitute(matcher, pattern, sub, input, 1);
matcher
- The regular expression matcher to execute the pattern
search.pattern
- The regular expression to search for and substitute
occurrences of.sub
- The Substitution used to substitute pattern occurences.input
- The String
on which to perform substitutions.
- A String comprising the input string with the substitutions,
if any, made. If no substitutions are made, the returned String
is the original input String.
- 1.0
substitute
public static String substitute(PatternMatcher matcher,
Pattern pattern,
Substitution sub,
String input,
int numSubs)
Searches a string for a pattern and replaces the first occurrences
of the pattern with a Substitution up to the number of
substitutions specified by the
numSubs parameter. A
numSubs value of
SUBSTITUTE_ALL will cause all occurrences
of the pattern to be replaced.
matcher
- The regular expression matcher to execute the pattern
search.pattern
- The regular expression to search for and substitute
occurrences of.sub
- The Substitution used to substitute pattern occurences.input
- The String
on which to perform substitutions.numSubs
- The number of substitutions to perform. Only the
first numSubs patterns encountered are
substituted. If you want to substitute all occurences
set this parameter to SUBSTITUTE_ALL .
- A String comprising the input string with the substitutions,
if any, made. If no substitutions are made, the returned String
is the original input String.
- 1.0
Copyright B) 2000-2003 Apache Software Foundation. All Rights Reserved.