org.apache.oro.text.perl.Perl5Util Maven / Gradle / Ivy
/*
* $Id: Perl5Util.java,v 1.19 2003/11/07 20:16:25 dfs Exp $
*
* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation", "Jakarta-Oro"
* must not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache"
* or "Jakarta-Oro", nor may "Apache" or "Jakarta-Oro" appear in their
* name, without prior written permission of the Apache Software Foundation.
*
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
*
* - [m]/pattern/[i][m][s][x],
*
- s/pattern/replacement/[g][i][m][o][s][x],
*
- and split().
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes.
*
* The objective of the class is to minimize the amount of code a Java
* programmer using Jakarta-ORO
* has to write to achieve the same results as Perl by
* transparently handling regular expression compilation, caching, and
* matching. A second objective is to use the same Perl pattern matching
* syntax to ease the task of Perl programmers transitioning to Java
* (this also reduces the number of parameters to a method).
* All the state affecting methods are synchronized to avoid
* the maintenance of explicit locks in multithreaded programs. This
* philosophy differs from the
* {@link org.apache.oro.text.regex} package, where
* you are expected to either maintain explicit locks, or more preferably
* create separate compiler and matcher instances for each thread.
*
* To use this class, first create an instance using the default constructor
* or initialize the instance with a PatternCache of your choosing using
* the alternate constructor. The default cache used by Perl5Util is a
* PatternCacheLRU of capacity GenericPatternCache.DEFAULT_CAPACITY. You may
* want to create a cache with a different capacity, a different
* cache replacement policy, or even devise your own PatternCache
* implementation. The PatternCacheLRU is probably the best general purpose
* pattern cache, but your specific application may be better served by
* a different cache replacement policy. You should remember that you can
* front-load a cache with all the patterns you will be using before
* initializing a Perl5Util instance, or you can just let Perl5Util
* fill the cache as you use it.
*
* You might use the class as follows:
*
* Perl5Util util = new Perl5Util();
* String line;
* DataInputStream input;
* PrintStream output;
*
* // Initialization of input and output omitted
* while((line = input.readLine()) != null) {
* // First find the line with the string we want to substitute because
* // it is cheaper than blindly substituting each line.
* if(util.match("/HREF=\"description1.html\"/")) {
* line = util.substitute("s/description1\\.html/about1.html/", line);
* }
* output.println(line);
* }
*
*
* A couple of things to remember when using this class are that the
* {@link #match match()} methods have the same meaning as
* {@link org.apache.oro.text.regex.Perl5Matcher#contains
* Perl5Matcher.contains()}
* and =~ m/pattern/ in Perl. The methods are named match
* to more closely associate them with Perl and to differentiate them
* from {@link org.apache.oro.text.regex.Perl5Matcher#matches
* Perl5Matcher.matches()}.
* A further thing to keep in mind is that the
* {@link MalformedPerl5PatternException} class is derived from
* RuntimeException which means you DON'T have to catch it. The reasoning
* behind this is that you will detect your regular expression mistakes
* as you write and debug your program when a MalformedPerl5PatternException
* is thrown during a test run. However, we STRONGLY recommend that you
* ALWAYS catch MalformedPerl5PatternException whenever you deal with a
* DYNAMICALLY created pattern. Relying on a fatal
* MalformedPerl5PatternException being thrown to detect errors while
* debugging is only useful for dealing with static patterns, that is, actual
* pregenerated strings present in your program. Patterns created from user
* input or some other dynamic method CANNOT be relied upon to be correct
* and MUST be handled by catching MalformedPerl5PatternException for your
* programs to be robust.
*
* Finally, as a convenience Perl5Util implements
* the {@link org.apache.oro.text.regex.MatchResult MatchResult} interface.
* The methods are merely wrappers which call the corresponding method of
* the last {@link org.apache.oro.text.regex.MatchResult MatchResult}
* found (which can be accessed with {@link #getMatch()}) by a match or
* substitution (or even a split, but this isn't particularly useful).
* At the moment, the
* {@link org.apache.oro.text.regex.MatchResult MatchResult} returned
* by {@link #getMatch()} is not stored in a thread-local variable. Therefore
* concurrent calls to {@link #getMatch()} will produce unpredictable
* results. So if your concurrent program requires the match results,
* you must protect the matching and the result retrieval in a critical
* section. If you do not need match results, you don't need to do anything
* special. If you feel the J2SE implementation of {@link #getMatch()}
* should use a thread-local variable and obviate the need for a critical
* section, please express your views on the oro-dev mailing list.
*
* @version @version@
* @since 1.0
* @see MalformedPerl5PatternException
* @see org.apache.oro.text.PatternCache
* @see org.apache.oro.text.PatternCacheLRU
* @see org.apache.oro.text.regex.MatchResult
*/
public final class Perl5Util implements MatchResult {
/** The regular expression to use to parse match expression. */
private static final String __matchExpression = "m?(\\W)(.*)\\1([imsx]*)";
/** The pattern cache to compile and store patterns */
private PatternCache __patternCache;
/** The hashtable to cache higher-level expressions */
private Cache __expressionCache;
/** The pattern matcher to perform matching operations. */
private Perl5Matcher __matcher;
/** The compiled match expression parsing regular expression. */
private Pattern __matchPattern;
/** The last match from a successful call to a matching method. */
private MatchResult __lastMatch;
/**
* A container for temporarily holding the results of a split before
* deleting trailing empty fields.
*/
private ArrayList __splitList;
/**
* Keeps track of the original input (for postMatch() and preMatch())
* methods. This will be discarded if the preMatch() and postMatch()
* methods are moved into the MatchResult interface.
*/
private Object __originalInput;
/**
* Keeps track of the begin and end offsets of the original input for
* the postMatch() and preMatch() methods.
*/
private int __inputBeginOffset, __inputEndOffset;
/** Used for default return value of post and pre Match() */
private static final String __nullString = "";
/**
* A constant passed to the {@link #split split()} methods indicating
* that all occurrences of a pattern should be used to split a string.
*/
public static final int SPLIT_ALL = Util.SPLIT_ALL;
/**
* A secondary constructor for Perl5Util. It initializes the Perl5Matcher
* used by the class to perform matching operations, but requires the
* programmer to provide a PatternCache instance for the class
* to use to compile and store regular expressions. You would want to
* use this constructor if you want to change the capacity or policy
* of the cache used. Example uses might be:
*
* // We know we're going to use close to 50 expressions a whole lot, so
* // we create a cache of the proper size.
* util = new Perl5Util(new PatternCacheLRU(50));
*
* or
*
* // We're only going to use a few expressions and know that second-chance
* // fifo is best suited to the order in which we are using the patterns.
* util = new Perl5Util(new PatternCacheFIFO2(10));
*
*/
public Perl5Util(PatternCache cache) {
__splitList = new ArrayList();
__matcher = new Perl5Matcher();
__patternCache = cache;
__expressionCache = new CacheLRU(cache.capacity());
__compilePatterns();
}
/**
* Default constructor for Perl5Util. This initializes the Perl5Matcher
* used by the class to perform matching operations and creates a
* default PatternCacheLRU instance to use to compile and cache regular
* expressions. The size of this cache is
* GenericPatternCache.DEFAULT_CAPACITY.
*/
public Perl5Util() {
this(new PatternCacheLRU());
}
/**
* Compiles the patterns (currently only the match expression) used to
* parse Perl5 expressions. Right now it initializes __matchPattern.
*/
private void __compilePatterns() {
Perl5Compiler compiler = new Perl5Compiler();
try {
__matchPattern =
compiler.compile(__matchExpression, Perl5Compiler.SINGLELINE_MASK);
} catch(MalformedPatternException e) {
// This should only happen during debugging.
//e.printStackTrace();
throw new RuntimeException(e.getMessage());
}
}
/**
* Parses a match expression and returns a compiled pattern.
* First checks the expression cache and if the pattern is not found,
* then parses the expression and fetches a compiled pattern from the
* pattern cache. Otherwise, just uses the pattern found in the
* expression cache. __matchPattern is used to parse the expression.
*
* @param pattern The Perl5 match expression to parse.
* @exception MalformedPerl5PatternException If there is an error parsing
* the expression.
*/
private Pattern __parseMatchExpression(String pattern)
throws MalformedPerl5PatternException
{
int index, compileOptions;
String options, regex;
MatchResult result;
Object obj;
Pattern ret;
obj = __expressionCache.getElement(pattern);
// Must catch ClassCastException because someone might incorrectly
// pass an s/// expression. try block is cheaper than checking
// instanceof
try {
if(obj != null)
return (Pattern)obj;
} catch(ClassCastException e) {
// Fall through and parse expression
}
if(!__matcher.matches(pattern, __matchPattern))
throw new
MalformedPerl5PatternException("Invalid expression: " +
pattern);
result = __matcher.getMatch();
regex = result.group(2);
compileOptions = Perl5Compiler.DEFAULT_MASK;
options = result.group(3);
if(options != null) {
index = options.length();
while(index-- > 0) {
switch(options.charAt(index)) {
case 'i' :
compileOptions |= Perl5Compiler.CASE_INSENSITIVE_MASK;
break;
case 'm' : compileOptions |= Perl5Compiler.MULTILINE_MASK; break;
case 's' : compileOptions |= Perl5Compiler.SINGLELINE_MASK; break;
case 'x' : compileOptions |= Perl5Compiler.EXTENDED_MASK; break;
default :
throw new
MalformedPerl5PatternException("Invalid options: " + options);
}
}
}
ret = __patternCache.getPattern(regex, compileOptions);
__expressionCache.addElement(pattern, ret);
return ret;
}
/**
* Searches for the first pattern match somewhere in a character array
* taking a pattern specified in Perl5 native format:
*
* [m]/pattern/[i][m][s][x]
*
* The m prefix is optional and the meaning of the optional
* trailing options are:
*
* - i
- case insensitive match
*
- m
- treat the input as consisting of multiple lines
*
- s
- treat the input as consisting of a single line
*
- x
- enable extended expression syntax incorporating whitespace
* and comments
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes.
*
* If the input contains the pattern, the org.apache.oro.text.regex.MatchResult
* can be obtained by calling {@link #getMatch()}.
* However, Perl5Util implements the MatchResult interface as a wrapper
* around the last MatchResult found, so you can call its methods to
* access match information.
*
* @param pattern The pattern to search for.
* @param input The char[] input to search.
* @return True if the input contains the pattern, false otherwise.
* @exception MalformedPerl5PatternException If there is an error in
* the pattern. You are not forced to catch this exception
* because it is derived from RuntimeException.
*/
public synchronized boolean match(String pattern, char[] input)
throws MalformedPerl5PatternException
{
boolean result;
__parseMatchExpression(pattern);
result = __matcher.contains(input, __parseMatchExpression(pattern));
if(result) {
__lastMatch = __matcher.getMatch();
__originalInput = input;
__inputBeginOffset = 0;
__inputEndOffset = input.length;
}
return result;
}
/**
* Searches for the first pattern match in a String taking
* a pattern specified in Perl5 native format:
*
* [m]/pattern/[i][m][s][x]
*
* The m prefix is optional and the meaning of the optional
* trailing options are:
*
* - i
- case insensitive match
*
- m
- treat the input as consisting of multiple lines
*
- s
- treat the input as consisting of a single line
*
- x
- enable extended expression syntax incorporating whitespace
* and comments
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes.
*
* If the input contains the pattern, the
* {@link org.apache.oro.text.regex.MatchResult MatchResult}
* can be obtained by calling {@link #getMatch()}.
* However, Perl5Util implements the MatchResult interface as a wrapper
* around the last MatchResult found, so you can call its methods to
* access match information.
*
* @param pattern The pattern to search for.
* @param input The String input to search.
* @return True if the input contains the pattern, false otherwise.
* @exception MalformedPerl5PatternException If there is an error in
* the pattern. You are not forced to catch this exception
* because it is derived from RuntimeException.
*/
public synchronized boolean match(String pattern, String input)
throws MalformedPerl5PatternException
{
return match(pattern, input.toCharArray());
}
/**
* Searches for the next pattern match somewhere in a
* org.apache.oro.text.regex.PatternMatcherInput instance, taking
* a pattern specified in Perl5 native format:
*
* [m]/pattern/[i][m][s][x]
*
* The m prefix is optional and the meaning of the optional
* trailing options are:
*
* - i
- case insensitive match
*
- m
- treat the input as consisting of multiple lines
*
- s
- treat the input as consisting of a single line
*
- x
- enable extended expression syntax incorporating whitespace
* and comments
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes.
*
* If the input contains the pattern, the
* {@link org.apache.oro.text.regex.MatchResult MatchResult}
* can be obtained by calling {@link #getMatch()}.
* However, Perl5Util implements the MatchResult interface as a wrapper
* around the last MatchResult found, so you can call its methods to
* access match information.
* After the call to this method, the PatternMatcherInput current offset
* is advanced to the end of the match, so you can use it to repeatedly
* search for expressions in the entire input using a while loop as
* explained in the {@link org.apache.oro.text.regex.PatternMatcherInput
* PatternMatcherInput} documentation.
*
* @param pattern The pattern to search for.
* @param input The PatternMatcherInput to search.
* @return True if the input contains the pattern, false otherwise.
* @exception MalformedPerl5PatternException If there is an error in
* the pattern. You are not forced to catch this exception
* because it is derived from RuntimeException.
*/
public synchronized boolean match(String pattern, PatternMatcherInput input)
throws MalformedPerl5PatternException
{
boolean result;
result = __matcher.contains(input, __parseMatchExpression(pattern));
if(result) {
__lastMatch = __matcher.getMatch();
__originalInput = input.getInput();
__inputBeginOffset = input.getBeginOffset();
__inputEndOffset = input.getEndOffset();
}
return result;
}
/**
* Returns the last match found by a call to a match(), substitute(), or
* split() method. This method is only intended for use to retrieve a match
* found by the last match found by a match() method. This method should
* be used when you want to save MatchResult instances. Otherwise, for
* simply accessing match information, it is more convenient to use the
* Perl5Util methods implementing the MatchResult interface.
*
* @return The org.apache.oro.text.regex.MatchResult instance containing the
* last match found.
*/
public synchronized MatchResult getMatch() {
return __lastMatch;
}
/**
* Substitutes a pattern in a given input with a replacement string.
* The substitution expression is specified in Perl5 native format:
*
* s/pattern/replacement/[g][i][m][o][s][x]
*
* The s prefix is mandatory and the meaning of the optional
* trailing options are:
*
* - g
- Substitute all occurrences of pattern with replacement.
* The default is to replace only the first occurrence.
*
- i
- perform a case insensitive match
*
- m
- treat the input as consisting of multiple lines
*
- o
- If variable interopolation is used, only evaluate the
* interpolation once (the first time). This is equivalent
* to using a numInterpolations argument of 1 in
* {@link org.apache.oro.text.regex.Util#substitute Util.substitute()}.
* The default is to compute each interpolation independently.
* See
* {@link org.apache.oro.text.regex.Util#substitute Util.substitute()}
* and {@link org.apache.oro.text.regex.Perl5Substitution Perl5Substitution}
* for more details on variable interpolation in
* substitutions.
*
- s
- treat the input as consisting of a single line
*
- x
- enable extended expression syntax incorporating whitespace
* and comments
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes. This is helpful to avoid backslashing. For example,
* using slashes you would have to do:
*
* numSubs = util.substitute(result, "s/foo\\/bar/goo\\/\\/baz/", input);
*
* when you could more easily write:
*
* numSubs = util.substitute(result, "s#foo/bar#goo//baz#", input);
*
* where the hashmarks are used instead of slashes.
*
* There is a special case of backslashing that you need to pay attention
* to. As demonstrated above, to denote a delimiter in the substituted
* string it must be backslashed. However, this can be a problem
* when you want to denote a backslash at the end of the substituted
* string. As of PerlTools 1.3, a new means of handling this
* situation has been implemented.
* In previous versions, the behavior was that
*
* "... a double backslash (quadrupled in the Java String) always
* represents two backslashes unless the second backslash is followed
* by the delimiter, in which case it represents a single backslash."
*
*
* The new behavior is that a backslash is always a backslash
* in the substitution portion of the expression unless it is used to
* escape a delimiter. A backslash is considered to escape a delimiter
* if an even number of contiguous backslashes preceed the backslash
* and the delimiter following the backslash is not the FINAL delimiter
* in the expression. Therefore, backslashes preceding final delimiters
* are never considered to escape the delimiter. The following, which
* used to be an invalid expression and require a special-case extra
* backslash, will now replace all instances of / with \:
*
* numSubs = util.substitute(result, "s#/#\\#g", input);
*
*
* @param result The StringBuffer in which to store the result of the
* substitutions. The buffer is only appended to.
* @param expression The Perl5 substitution regular expression.
* @param input The input on which to perform substitutions.
* @return The number of substitutions made.
* @exception MalformedPerl5PatternException If there is an error in
* the expression. You are not forced to catch this exception
* because it is derived from RuntimeException.
* @since 2.0.6
*/
// Expression parsing will have to be moved into a separate method if
// there are going to be variations of this method.
public synchronized int substitute(StringBuffer result, String expression,
String input)
throws MalformedPerl5PatternException
{
boolean backslash, finalDelimiter;
int index, compileOptions, numSubstitutions, numInterpolations;
int firstOffset, secondOffset, thirdOffset, subCount;
StringBuffer replacement;
Pattern compiledPattern;
char exp[], delimiter;
ParsedSubstitutionEntry entry;
Perl5Substitution substitution;
Object obj;
obj = __expressionCache.getElement(expression);
__nullTest:
if(obj != null) {
// Must catch ClassCastException because someone might incorrectly
// pass an m// expression. try block is cheaper than checking
// instanceof. We want to go ahead with parsing just in case so
// we break.
try {
entry = (ParsedSubstitutionEntry)obj;
} catch(ClassCastException e) {
break __nullTest;
}
subCount =
Util.substitute(result, __matcher, entry._pattern, entry._substitution,
input, entry._numSubstitutions);
__lastMatch = __matcher.getMatch();
return subCount;
}
exp = expression.toCharArray();
// Make sure basic conditions for a valid substitution expression hold.
if(exp.length < 4 || exp[0] != 's' || Character.isLetterOrDigit(exp[1])
|| exp[1] == '-')
throw new
MalformedPerl5PatternException("Invalid expression: " + expression);
delimiter = exp[1];
firstOffset = 2;
secondOffset = thirdOffset = -1;
backslash = false;
// Parse pattern
for(index = firstOffset; index < exp.length; index++) {
if(exp[index] == '\\')
backslash = !backslash;
else if(exp[index] == delimiter && !backslash) {
secondOffset = index;
break;
} else if(backslash)
backslash = !backslash;
}
if(secondOffset == -1 || secondOffset == exp.length - 1)
throw new
MalformedPerl5PatternException("Invalid expression: " + expression);
// Parse replacement string
backslash = false;
finalDelimiter = true;
replacement = new StringBuffer(exp.length - secondOffset);
for(index = secondOffset + 1; index < exp.length; index++) {
if(exp[index] == '\\') {
backslash = !backslash;
// 05/05/99 dfs
// We unbackslash backslashed delimiters in the replacement string
// only if we're on an odd backslash and there is another occurrence
// of a delimiter later in the string.
if(backslash && index + 1 < exp.length && exp[index + 1] == delimiter
&& expression.lastIndexOf(delimiter, exp.length - 1) != (index + 1))
{
finalDelimiter = false;
continue;
}
} else if(exp[index] == delimiter && finalDelimiter) {
thirdOffset = index;
break;
} else {
backslash = false;
finalDelimiter = true;
}
replacement.append(exp[index]);
}
if(thirdOffset == -1)
throw new
MalformedPerl5PatternException("Invalid expression: " + expression);
compileOptions = Perl5Compiler.DEFAULT_MASK;
numSubstitutions = 1;
// Single quotes cause no interpolations to be performed in replacement
if(delimiter != '\'')
numInterpolations = Perl5Substitution.INTERPOLATE_ALL;
else
numInterpolations = Perl5Substitution.INTERPOLATE_NONE;
// Parse options
for(index = thirdOffset + 1; index < exp.length; index++) {
switch(exp[index]) {
case 'i' :
compileOptions |= Perl5Compiler.CASE_INSENSITIVE_MASK;
break;
case 'm' : compileOptions |= Perl5Compiler.MULTILINE_MASK; break;
case 's' : compileOptions |= Perl5Compiler.SINGLELINE_MASK; break;
case 'x' : compileOptions |= Perl5Compiler.EXTENDED_MASK; break;
case 'g' : numSubstitutions = Util.SUBSTITUTE_ALL; break;
case 'o' : numInterpolations = 1; break;
default :
throw new
MalformedPerl5PatternException("Invalid option: " + exp[index]);
}
}
compiledPattern =
__patternCache.getPattern(new String(exp, firstOffset,
secondOffset - firstOffset),
compileOptions);
substitution =
new Perl5Substitution(replacement.toString(), numInterpolations);
entry = new ParsedSubstitutionEntry(compiledPattern, substitution,
numSubstitutions);
__expressionCache.addElement(expression, entry);
subCount =
Util.substitute(result, __matcher, compiledPattern, substitution,
input, numSubstitutions);
__lastMatch = __matcher.getMatch();
return subCount;
}
/**
* Substitutes a pattern in a given input with a replacement string.
* The substitution expression is specified in Perl5 native format.
*
* - Calling this method is the same as:
* -
*
* String result;
* StringBuffer buffer = new StringBuffer();
* perl.substitute(buffer, expression, input);
* result = buffer.toString();
*
*
*
* @param expression The Perl5 substitution regular expression.
* @param input The input on which to perform substitutions.
* @return The input as a String after substitutions have been performed.
* @exception MalformedPerl5PatternException If there is an error in
* the expression. You are not forced to catch this exception
* because it is derived from RuntimeException.
* @since 1.0
* @see #substitute
*/
public synchronized String substitute(String expression, String input)
throws MalformedPerl5PatternException
{
StringBuffer result = new StringBuffer();
substitute(result, expression, input);
return result.toString();
}
/**
* Splits a String into strings that are appended to a List, but no more
* than a specified limit. The String is split using a regular expression
* as the delimiter. The regular expression is a pattern specified
* in Perl5 native format:
*
* [m]/pattern/[i][m][s][x]
*
* The m prefix is optional and the meaning of the optional
* trailing options are:
*
* - i
- case insensitive match
*
- m
- treat the input as consisting of multiple lines
*
- s
- treat the input as consisting of a single line
*
- x
- enable extended expression syntax incorporating whitespace
* and comments
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes.
*
* The limit parameter causes the string to be split on at most the first
* limit - 1 number of pattern occurences.
*
* Of special note is that this split method performs EXACTLY the same
* as the Perl split() function. In other words, if the split pattern
* contains parentheses, additional Vector elements are created from
* each of the matching subgroups in the pattern. Using an example
* similar to the one from the Camel book:
*
* split(list, "/([,-])/", "8-12,15,18")
*
* produces the Vector containing:
*
* { "8", "-", "12", ",", "15", ",", "18" }
*
* Furthermore, the following Perl behavior is observed: "leading empty
* fields are preserved, and empty trailing one are deleted." This
* has the effect that a split on a zero length string returns an empty
* list.
* The {@link org.apache.oro.text.regex.Util#split Util.split()} method
* does NOT implement these behaviors because it is intended to
* be a general self-consistent and predictable split function usable
* with Pattern instances other than Perl5Pattern.
*
* @param results
* A Collection to which the substrings of the input
* that occur between the regular expression delimiter occurences
* are appended. 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. The Collection must support the
* addAll(Collection) operation.
* @param pattern The regular expression to use as a split delimiter.
* @param input The String to split.
* @param limit The limit on the size of the returned Vector.
* Values <= 0 produce the same behavior as 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.
* @exception MalformedPerl5PatternException If there is an error in
* the expression. You are not forced to catch this exception
* because it is derived from RuntimeException.
*/
public synchronized void split(Collection results, String pattern,
String input, int limit)
throws MalformedPerl5PatternException
{
int beginOffset, groups, index;
String group;
MatchResult currentResult = null;
PatternMatcherInput pinput;
Pattern compiledPattern;
compiledPattern = __parseMatchExpression(pattern);
pinput = new PatternMatcherInput(input);
beginOffset = 0;
while(--limit != 0 && __matcher.contains(pinput, compiledPattern)) {
currentResult = __matcher.getMatch();
__splitList.add(input.substring(beginOffset,
currentResult.beginOffset(0)));
if((groups = currentResult.groups()) > 1) {
for(index = 1; index < groups; ++index) {
group = currentResult.group(index);
if(group != null && group.length() > 0)
__splitList.add(group);
}
}
beginOffset = currentResult.endOffset(0);
}
__splitList.add(input.substring(beginOffset, input.length()));
// Remove all trailing empty fields.
for(int i = __splitList.size() - 1; i >= 0; --i) {
String str;
str = (String)__splitList.get(i);
if(str.length() == 0)
__splitList.remove(i);
else
break;
}
results.addAll(__splitList);
__splitList.clear();
// Just for the sake of completeness
__lastMatch = currentResult;
}
/**
* This method is identical to calling:
*
* split(results, pattern, input, SPLIT_ALL);
*
*/
public synchronized void split(Collection results, String pattern,
String input)
throws MalformedPerl5PatternException
{
split(results, pattern, input, SPLIT_ALL);
}
/**
* Splits input in the default Perl manner, splitting on all whitespace.
* This method is identical to calling:
*
* split(results, "/\\s+/", input);
*
*/
public synchronized void split(Collection results, String input)
throws MalformedPerl5PatternException
{
split(results, "/\\s+/", input);
}
/**
* Splits a String into strings contained in a Vector of size no greater
* than a specified limit. The String is split using a regular expression
* as the delimiter. The regular expression is a pattern specified
* in Perl5 native format:
*
* [m]/pattern/[i][m][s][x]
*
* The m prefix is optional and the meaning of the optional
* trailing options are:
*
* - i
- case insensitive match
*
- m
- treat the input as consisting of multiple lines
*
- s
- treat the input as consisting of a single line
*
- x
- enable extended expression syntax incorporating whitespace
* and comments
*
* As with Perl, any non-alphanumeric character can be used in lieu of
* the slashes.
*
* The limit parameter causes the string to be split on at most the first
* limit - 1 number of pattern occurences.
*
* Of special note is that this split method performs EXACTLY the same
* as the Perl split() function. In other words, if the split pattern
* contains parentheses, additional Vector elements are created from
* each of the matching subgroups in the pattern. Using an example
* similar to the one from the Camel book:
*
* split("/([,-])/", "8-12,15,18")
*
* produces the Vector containing:
*
* { "8", "-", "12", ",", "15", ",", "18" }
*
* The {@link org.apache.oro.text.regex.Util#split Util.split()} method
* does NOT implement this particular behavior because it is intended to
* be usable with Pattern instances other than Perl5Pattern.
*
* @deprecated Use
* {@link #split(Collection results, String pattern, String input, int limit)}
* instead.
* @param pattern The regular expression to use as a split delimiter.
* @param input The String to split.
* @param limit The limit on the size of the returned Vector.
* Values <= 0 produce the same behavior as 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.
* @return 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.
* @exception MalformedPerl5PatternException If there is an error in
* the expression. You are not forced to catch this exception
* because it is derived from RuntimeException.
*/
public synchronized Vector split(String pattern, String input, int limit)
throws MalformedPerl5PatternException
{
Vector results = new Vector(20);
split(results, pattern, input, limit);
return results;
}
/**
* This method is identical to calling:
*
* split(pattern, input, SPLIT_ALL);
*
* @deprecated Use
* {@link #split(Collection results, String pattern, String input)} instead.
*/
public synchronized Vector split(String pattern, String input)
throws MalformedPerl5PatternException
{
return split(pattern, input, SPLIT_ALL);
}
/**
* Splits input in the default Perl manner, splitting on all whitespace.
* This method is identical to calling:
*
* split("/\\s+/", input);
*
* @deprecated Use
* {@link #split(Collection results, String input)} instead.
*/
public synchronized Vector split(String input)
throws MalformedPerl5PatternException
{
return split("/\\s+/", input);
}
//
// MatchResult interface methods.
//
/**
* Returns the length of the last match found.
*
* @return The length of the last match found.
*/
public synchronized int length() {
return __lastMatch.length();
}
/**
* @return The number of groups contained in the last match found.
* This number includes the 0th group. In other words, the
* result refers to the number of parenthesized subgroups plus
* the entire match itself.
*/
public synchronized int groups() {
return __lastMatch.groups();
}
/**
* Returns the contents of the parenthesized subgroups of the last match
* found according to the behavior dictated by the MatchResult interface.
*
* @param group The pattern subgroup to return.
* @return A string containing the indicated pattern subgroup. Group
* 0 always refers to the entire match. If a group was never
* matched, it returns null. This is not to be confused with
* a group matching the null string, which will return a String
* of length 0.
*/
public synchronized String group(int group) {
return __lastMatch.group(group);
}
/**
* Returns the begin offset of the subgroup of the last match found
* relative the beginning of the match.
*
* @param group The pattern subgroup.
* @return The offset into group 0 of the first token in the indicated
* pattern subgroup. If a group was never matched or does
* not exist, returns -1. Be aware that a group that matches
* the null string at the end of a match will have an offset
* equal to the length of the string, so you shouldn't blindly
* use the offset to index an array or String.
*/
public synchronized int begin(int group) {
return __lastMatch.begin(group);
}
/**
* Returns the end offset of the subgroup of the last match found
* relative the beginning of the match.
*
* @param group The pattern subgroup.
* @return Returns one plus the offset into group 0 of the last token in
* the indicated pattern subgroup. If a group was never matched
* or does not exist, returns -1. A group matching the null
* string will return its start offset.
*/
public synchronized int end(int group) {
return __lastMatch.end(group);
}
/**
* Returns an offset marking the beginning of the last pattern match
* found relative to the beginning of the input from which the match
* was extracted.
*
* @param group The pattern subgroup.
* @return The offset of the first token in the indicated
* pattern subgroup. If a group was never matched or does
* not exist, returns -1.
*/
public synchronized int beginOffset(int group) {
return __lastMatch.beginOffset(group);
}
/**
* Returns an offset marking the end of the last pattern match found
* relative to the beginning of the input from which the match was
* extracted.
*
* @param group The pattern subgroup.
* @return Returns one plus the offset of the last token in
* the indicated pattern subgroup. If a group was never matched
* or does not exist, returns -1. A group matching the null
* string will return its start offset.
*/
public synchronized int endOffset(int group) {
return __lastMatch.endOffset(group);
}
/**
* Returns the same as group(0).
*
* @return A string containing the entire match.
*/
public synchronized String toString() {
if(__lastMatch == null)
return null;
return __lastMatch.toString();
}
/**
* Returns the part of the input preceding the last match found.
*
* @return The part of the input following the last match found.
*/
public synchronized String preMatch() {
int begin;
if(__originalInput == null)
return __nullString;
begin = __lastMatch.beginOffset(0);
if(begin <= 0)
return __nullString;
if(__originalInput instanceof char[]) {
char[] input;
input = (char[])__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(begin > input.length)
begin = input.length;
return new String(input, __inputBeginOffset, begin);
} else if(__originalInput instanceof String) {
String input;
input = (String)__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(begin > input.length())
begin = input.length();
return input.substring(__inputBeginOffset, begin);
}
return __nullString;
}
/**
* Returns the part of the input following the last match found.
*
* @return The part of the input following the last match found.
*/
public synchronized String postMatch() {
int end;
if(__originalInput == null)
return __nullString;
end = __lastMatch.endOffset(0);
if(end < 0)
return __nullString;
if(__originalInput instanceof char[]) {
char[] input;
input = (char[])__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(end >= input.length)
return __nullString;
return new String(input, end, __inputEndOffset - end);
} else if(__originalInput instanceof String) {
String input;
input = (String)__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(end >= input.length())
return __nullString;
return input.substring(end, __inputEndOffset);
}
return __nullString;
}
/**
* Returns the part of the input preceding the last match found as a
* char array. This method eliminates the extra
* buffer copying caused by preMatch().toCharArray().
*
* @return The part of the input preceding the last match found as a char[].
* If the result is of zero length, returns null instead of a zero
* length array.
*/
public synchronized char[] preMatchCharArray() {
int begin;
char[] result = null;
if(__originalInput == null)
return null;
begin = __lastMatch.beginOffset(0);
if(begin <= 0)
return null;
if(__originalInput instanceof char[]) {
char[] input;
input = (char[])__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(begin >= input.length)
begin = input.length;
result = new char[begin - __inputBeginOffset];
System.arraycopy(input, __inputBeginOffset, result, 0, result.length);
} else if(__originalInput instanceof String) {
String input;
input = (String)__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(begin >= input.length())
begin = input.length();
result = new char[begin - __inputBeginOffset];
input.getChars(__inputBeginOffset, begin, result, 0);
}
return result;
}
/**
* Returns the part of the input following the last match found as a char
* array. This method eliminates the extra buffer copying caused by
* preMatch().toCharArray().
*
* @return The part of the input following the last match found as a char[].
* If the result is of zero length, returns null instead of a zero
* length array.
*/
public synchronized char[] postMatchCharArray() {
int end;
char[] result = null;
if(__originalInput == null)
return null;
end = __lastMatch.endOffset(0);
if(end < 0)
return null;
if(__originalInput instanceof char[]) {
int length;
char[] input;
input = (char[])__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(end >= input.length)
return null;
length = __inputEndOffset - end;
result = new char[length];
System.arraycopy(input, end, result, 0, length);
} else if(__originalInput instanceof String) {
String input;
input = (String)__originalInput;
// Just in case we make sure begin offset is in bounds. It should
// be but we're paranoid.
if(end >= __inputEndOffset)
return null;
result = new char[__inputEndOffset - end];
input.getChars(end, __inputEndOffset, result, 0);
}
return result;
}
}