org.apache.oro.text.regex

Class Perl5Substitution

Implemented Interfaces:
Substitution

public class Perl5Substitution
extends StringSubstitution

Perl5Substitution implements a Substitution consisting of a literal string, but allowing Perl5 variable interpolation referencing saved groups in a match. This class is intended for use with Util.substitute.

The substitution string may contain variable interpolations referring to the saved parenthesized groups of the search pattern. A variable interpolation is denoted by $1, or $2, or $3, etc. If you want such expressions to be interpreted literally, you should set the numInterpolations parameter to INTERPOLATE_NONE . It is easiest to explain what an interpolated variable does by giving an example:

A final thing to keep in mind is that if you use an interpolation variable that corresponds to a group not contained in the match, then it is interpreted as the empty string. So given the regular expression from the example, and a substitution expression of a$2-, the result of the last sample input would be:

Tank a- 85  Tank a- 32  Tank a- 22
The special substitution $& will interpolate the entire portion of the input matched by the regular expression. $0 will do the same, but it is recommended that it be avoided because the latest versions of Perl use $0 to store the program name rather than duplicate the behavior of $&. Also, the result of substituting $ followed by a non-positive integer is undefined. In order to include a $ in a substitution, it should be escaped with a backslash (e.g., "\\$0").

Perl5 double-quoted string case modification is also supported in the substitution. The following escape sequences are supported:

The double backslashes are shown to remind you that to make a backslash get past Java's string handling and appear as a backslash to the substitution, you must escape the backslash.
Version:
2.0.8
Since:
1.1
See Also:
Substitution, Util, Util.substitute, Substitution, StringSubstitution

Field Summary

static int
INTERPOLATE_ALL
A constant used when creating a Perl5Substitution indicating that interpolation variables should be computed relative to the most recent pattern match.
static int
INTERPOLATE_NONE
A constant used when creating a Perl5Substitution indicating that interpolation variables should be interpreted literally, effectively disabling interpolation.

Constructor Summary

Perl5Substitution()
Default constructor initializing substitution to a zero length String and the number of interpolations to INTERPOLATE_ALL.
Perl5Substitution(String substitution)
Creates a Perl5Substitution using the specified substitution and setting the number of interpolations to INTERPOLATE_ALL.
Perl5Substitution(String substitution, int numInterpolations)
Creates a Perl5Substitution using the specified substitution and setting the number of interpolations to the specified value.

Method Summary

void
appendSubstitution(StringBuffer appendBuffer, MatchResult match, int substitutionCount, PatternMatcherInput originalInput, PatternMatcher matcher, Pattern pattern)
Appends the substitution to a buffer containing the original input with substitutions applied for the pattern matches found so far.
void
setSubstitution(String substitution)
Sets the substitution represented by this Perl5Substitution, also setting the number of interpolations to INTERPOLATE_ALL.
void
setSubstitution(String substitution, int numInterpolations)
Sets the substitution represented by this Perl5Substitution, also setting the number of interpolations to the specified value.

Methods inherited from class org.apache.oro.text.regex.StringSubstitution

appendSubstitution, getSubstitution, setSubstitution, toString

Field Details

INTERPOLATE_ALL

public static final int INTERPOLATE_ALL
A constant used when creating a Perl5Substitution indicating that interpolation variables should be computed relative to the most recent pattern match.
Field Value:
0

INTERPOLATE_NONE

public static final int INTERPOLATE_NONE
A constant used when creating a Perl5Substitution indicating that interpolation variables should be interpreted literally, effectively disabling interpolation.
Field Value:
-1

Constructor Details

Perl5Substitution

public Perl5Substitution()

Perl5Substitution

public Perl5Substitution(String substitution)
Parameters:
substitution - The string to use as a substitution.

Perl5Substitution

public Perl5Substitution(String substitution,
                         int numInterpolations)
Creates a Perl5Substitution using the specified substitution and setting the number of interpolations to the specified value.

Parameters:
substitution - The string to use as a substitution.
numInterpolations - If set to INTERPOLATE_NONE, interpolation variables are interpreted literally and not as references to the saved parenthesized groups of a pattern match. If set to INTERPOLATE_ALL , all variable interpolations are computed relative to the pattern match responsible for the current substitution. If set to a positive integer, the first numInterpolations substitutions have their variable interpolation performed relative to the most recent match, but the remaining substitutions have their variable interpolations performed relative to the numInterpolations 'th match.

Method Details

appendSubstitution

public void appendSubstitution(StringBuffer appendBuffer,
                               MatchResult match,
                               int substitutionCount,
                               PatternMatcherInput originalInput,
                               PatternMatcher matcher,
                               Pattern pattern)
Appends the substitution to a buffer containing the original input with substitutions applied for the pattern matches found so far. See Substitution.appendSubstition() for more details regarding the expected behavior of this method.

Specified by:
appendSubstitution in interface Substitution
Overrides:
appendSubstitution in interface StringSubstitution
Parameters:
appendBuffer - The buffer containing the new string resulting from performing substitutions on the original input.
match - The current match causing a substitution to be made.
substitutionCount - The number of substitutions that have been performed so far by Util.substitute.
originalInput - The original input upon which the substitutions are being performed. This is a read-only parameter and is not modified.
matcher - The PatternMatcher used to find the current match.
pattern - The Pattern used to find the current match.

setSubstitution

public void setSubstitution(String substitution)
Sets the substitution represented by this Perl5Substitution, also setting the number of interpolations to INTERPOLATE_ALL. You should use this method in order to avoid repeatedly allocating new Perl5Substitutions. It is recommended that you allocate a single Perl5Substitution and reuse it by using this method when appropriate.

Overrides:
setSubstitution in interface StringSubstitution
Parameters:
substitution - The string to use as a substitution.

setSubstitution

public void setSubstitution(String substitution,
                            int numInterpolations)
Sets the substitution represented by this Perl5Substitution, also setting the number of interpolations to the specified value. You should use this method in order to avoid repeatedly allocating new Perl5Substitutions. It is recommended that you allocate a single Perl5Substitution and reuse it by using this method when appropriate.

Parameters:
substitution - The string to use as a substitution.
numInterpolations - If set to INTERPOLATE_NONE, interpolation variables are interpreted literally and not as references to the saved parenthesized groups of a pattern match. If set to INTERPOLATE_ALL , all variable interpolations are computed relative to the pattern match responsible for the current substitution. If set to a positive integer, the first numInterpolations substitutions have their variable interpolation performed relative to the most recent match, but the remaining substitutions have their variable interpolations performed relative to the numInterpolations 'th match.

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