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.\" ========================================================================
.\"
.IX Title "Regexp::Common::comment 3pm"
.TH Regexp::Common::comment 3pm "2017-06-17" "perl v5.24.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Regexp::Common::comment \-\- provide regexes for comments.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use Regexp::Common qw /comment/;
\&
\&    while (<>) {
\&        /$RE{comment}{C}/       and  print "Contains a C comment\en";
\&        /$RE{comment}{C++}/     and  print "Contains a C++ comment\en";
\&        /$RE{comment}{PHP}/     and  print "Contains a PHP comment\en";
\&        /$RE{comment}{Java}/    and  print "Contains a Java comment\en";
\&        /$RE{comment}{Perl}/    and  print "Contains a Perl comment\en";
\&        /$RE{comment}{awk}/     and  print "Contains an awk comment\en";
\&        /$RE{comment}{HTML}/    and  print "Contains an HTML comment\en";
\&    }
\&
\&    use Regexp::Common qw /comment RE_comment_HTML/;
\&
\&    while (<>) {
\&        $_ =~ RE_comment_HTML() and  print "Contains an HTML comment\en";
\&    }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Please consult the manual of Regexp::Common for a general description
of the works of this interface.
.PP
Do not use this module directly, but load it via \fIRegexp::Common\fR.
.PP
This modules gives you regular expressions for comments in various
languages.
.SS "\s-1THE LANGUAGES\s0"
.IX Subsection "THE LANGUAGES"
Below, the comments of each of the languages are described.
The patterns are available as \f(CW$RE{comment}{\f(CILANG\f(CW}\fR, foreach
language \fI\s-1LANG\s0\fR. Some languages have variants; it's described
at the individual languages how to get the patterns for the variants.
Unless mentioned otherwise,
\&\f(CW\*(C`{\-keep}\*(C'\fR sets \f(CW$1\fR, \f(CW$2\fR, \f(CW$3\fR and \f(CW$4\fR to the entire comment,
the opening marker, the content of the comment, and the closing marker
(for many languages, the latter is a newline) respectively.
.IP "\s-1ABC\s0" 4
.IX Item "ABC"
Comments in \fI\s-1ABC\s0\fR start with a backslash (\f(CW\*(C`\e\*(C'\fR), and last till
the end of the line.
See <http://homepages.cwi.nl/%7Esteven/abc/>.
.IP "Ada" 4
.IX Item "Ada"
Comments in \fIAda\fR start with \f(CW\*(C`\-\-\*(C'\fR, and last till the end of the line.
.IP "Advisor" 4
.IX Item "Advisor"
\&\fIAdvisor\fR is a language used by the \s-1HP\s0 product \fIglance\fR. Comments for
this language start with either \f(CW\*(C`#\*(C'\fR or \f(CW\*(C`//\*(C'\fR, and last till the
end of the line.
.IP "Advsys" 4
.IX Item "Advsys"
Comments for the \fIAdvsys\fR language start with \f(CW\*(C`;\*(C'\fR and last till
the end of the line. See also <http://www.wurb.com/if/devsys/12>.
.IP "Alan" 4
.IX Item "Alan"
\&\fIAlan\fR comments start with \f(CW\*(C`\-\-\*(C'\fR, and last till the end of the line.
See also <http://w1.132.telia.com/~u13207378/alan/manual/alanTOC.html>.
.IP "Algol 60" 4
.IX Item "Algol 60"
Comments in the \fIAlgol 60\fR language start with the keyword \f(CW\*(C`comment\*(C'\fR,
and end with a \f(CW\*(C`;\*(C'\fR. See <http://www.masswerk.at/algol60/report.htm>.
.IP "Algol 68" 4
.IX Item "Algol 68"
In \fIAlgol 68\fR, comments are either delimited by \f(CW\*(C`#\*(C'\fR, or by one of the
keywords \f(CW\*(C`co\*(C'\fR or \f(CW\*(C`comment\*(C'\fR. The keywords should not be part of another
word. See <http://westein.arb\-phys.uni\-dortmund.de/~wb/a68s.txt>.
With \f(CW\*(C`{\-keep}\*(C'\fR, only \f(CW$1\fR will be set, returning the entire comment.
.IP "\s-1ALPACA\s0" 4
.IX Item "ALPACA"
The \fI\s-1ALPACA\s0\fR language has comments starting with \f(CW\*(C`/*\*(C'\fR and ending with \f(CW\*(C`*/\*(C'\fR.
.IP "awk" 4
.IX Item "awk"
The \fIawk\fR programming language uses comments that start with \f(CW\*(C`#\*(C'\fR
and end at the end of the line.
.IP "B" 4
.IX Item "B"
The \fIB\fR language has comments starting with \f(CW\*(C`/*\*(C'\fR and ending with \f(CW\*(C`*/\*(C'\fR.
.IP "\s-1BASIC\s0" 4
.IX Item "BASIC"
There are various forms of \s-1BASIC\s0 around. Currently, we only support the
variant supported by \fImvEnterprise\fR, whose pattern is available as
\&\f(CW$RE{comment}{BASIC}{mvEnterprise}\fR. Comments in this language start with a
\&\f(CW\*(C`!\*(C'\fR, a \f(CW\*(C`*\*(C'\fR or the keyword \f(CW\*(C`REM\*(C'\fR, and end till the end of the line. See
<http://www.rainingdata.com/products/beta/docs/mve/50/ReferenceManual/Basic.pdf>.
.IP "Beatnik" 4
.IX Item "Beatnik"
The esotoric language \fIBeatnik\fR only uses words consisting of letters.
Words are scored according to the rules of Scrabble. Words scoring less
than 5 points, or 18 points or more are considered comments (although
the compiler might mock at you if you score less than 5 points).
Regardless whether \f(CW\*(C`{\-keep}\*(C'\fR, \f(CW$1\fR will be set, and set to the
entire comment. This pattern requires \fIperl 5.8.0\fR or newer.
.IP "beta-Juliet" 4
.IX Item "beta-Juliet"
The \fIbeta-Juliet\fR programming language has comments that start with
\&\f(CW\*(C`//\*(C'\fR and that continue till the end of the line. See also
<http://www.catseye.mb.ca/esoteric/b\-juliet/index.html>.
.IP "Befunge\-98" 4
.IX Item "Befunge-98"
The esotoric language \fIBefunge\-98\fR uses comments that start and end
with a \f(CW\*(C`;\*(C'\fR. See <http://www.catseye.mb.ca/esoteric/befunge/98/spec98.html>.
.IP "\s-1BML                 \s0" 4
.IX Item "BML "
\&\fI\s-1BML\s0\fR, or \fIBetter Markup Language\fR is an \s-1HTML\s0 templating language that
uses comments starting with \f(CW\*(C`<?c_\*(C'\fR, and ending with \f(CW\*(C`c_?>\*(C'\fR.
See <http://www.livejournal.com/doc/server/bml.index.html>.
.IP "Brainfuck" 4
.IX Item "Brainfuck"
The minimal language \fIBrainfuck\fR uses only eight characters, 
\&\f(CW\*(C`<\*(C'\fR, \f(CW\*(C`>\*(C'\fR, \f(CW\*(C`[\*(C'\fR, \f(CW\*(C`]\*(C'\fR, \f(CW\*(C`+\*(C'\fR, \f(CW\*(C`\-\*(C'\fR, \f(CW\*(C`.\*(C'\fR and \f(CW\*(C`,\*(C'\fR.
Any other characters are considered comments. With \f(CW\*(C`{\-keep}\*(C'\fR,
\&\f(CW$1\fR is set to the entire comment.
.IP "C" 4
.IX Item "C"
The \fIC\fR language has comments starting with \f(CW\*(C`/*\*(C'\fR and ending with \f(CW\*(C`*/\*(C'\fR.
.IP "C\*(--" 4
.IX Item "C"
The \fIC\*(--\fR language has comments starting with \f(CW\*(C`/*\*(C'\fR and ending with \f(CW\*(C`*/\*(C'\fR.
See <http://cs.uas.arizona.edu/classes/453/programs/C\*(--Spec.html>.
.IP "\*(C+" 4
.IX Item ""
The \fI\*(C+\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment.
.IP "C#" 4
.IX Item "C#"
The \fIC#\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment.
See <http://msdn.microsoft.com/library/default.asp?url=/library/en\-us/csspec/html/vclrfcsharpspec_C.asp>.
.IP "Caml" 4
.IX Item "Caml"
Comments in \fICaml\fR start with \f(CW\*(C`(*\*(C'\fR, end with \f(CW\*(C`*)\*(C'\fR, and can be nested.
See <http://www.cs.caltech.edu/courses/cs134/cs134b/book.pdf> and
<http://pauillac.inria.fr/caml/index\-eng.html>.
.IP "Cg" 4
.IX Item "Cg"
The \fICg\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment.
See <http://developer.nvidia.com/attach/3722>.
.IP "\s-1CLU\s0" 4
.IX Item "CLU"
In \f(CW\*(C`CLU\*(C'\fR, a comment starts with a procent sign (\f(CW\*(C`%\*(C'\fR), and ends with the
next newline. See <ftp://ftp.lcs.mit.edu:/pub/pclu/CLU\-syntax.ps> and
<http://www.pmg.lcs.mit.edu/CLU.html>.
.IP "\s-1COBOL\s0" 4
.IX Item "COBOL"
Traditionally, comments in \fI\s-1COBOL\s0\fR are indicated by an asteriks in the
seventh column. This is what the pattern matches. Modern compiler may
more lenient though. See <http://www.csis.ul.ie/cobol/Course/COBOLIntro.htm>,
and <http://www.csis.ul.ie/cobol/default.htm>.
.IP "\s-1CQL\s0" 4
.IX Item "CQL"
Comments in the chess query language (\fI\s-1CQL\s0\fR) start with a semi colon
(\f(CW\*(C`;\*(C'\fR) and last till the end of the line. See <http://www.rbnn.com/cql/>.
.IP "Crystal Report" 4
.IX Item "Crystal Report"
The formula editor in \fICrystal Reports\fR uses comments that start
with \f(CW\*(C`//\*(C'\fR, and end with the end of the line.
.IP "Dylan" 4
.IX Item "Dylan"
There are two types of comments in \fIDylan\fR. They either start with
\&\f(CW\*(C`//\*(C'\fR, or are nested comments, delimited with \f(CW\*(C`/*\*(C'\fR and \f(CW\*(C`*/\*(C'\fR.
Under \f(CW\*(C`{\-keep}\*(C'\fR, only \f(CW$1\fR will be set, returning the entire comment.
This pattern requires \fIperl 5.6.0\fR or newer.
.IP "ECMAScript" 4
.IX Item "ECMAScript"
The \fIECMAScript\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment. \fIJavaScript\fR is Netscapes implementation
of \fIECMAScript\fR. See
<http://www.ecma\-international.org/publications/files/ecma\-st/Ecma\-262.pdf>,
and <http://www.ecma\-international.org/publications/standards/Ecma\-262.htm>.
.IP "Eiffel" 4
.IX Item "Eiffel"
\&\fIEiffel\fR comments start with \f(CW\*(C`\-\-\*(C'\fR, and last till the end of the line.
.IP "False" 4
.IX Item "False"
In \fIFalse\fR, comments start with \f(CW\*(C`{\*(C'\fR and end with \f(CW\*(C`}\*(C'\fR.
See <http://wouter.fov120.com/false/false.txt>
.IP "\s-1FPL\s0" 4
.IX Item "FPL"
The \fI\s-1FPL\s0\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment.
.IP "Forth" 4
.IX Item "Forth"
Comments in Forth start with \f(CW\*(C`\e\*(C'\fR, and end with the end of the line.
See also <http://docs.sun.com/sb/doc/806\-1377\-10>.
.IP "Fortran" 4
.IX Item "Fortran"
There are two forms of \fIFortran\fR. There's free form \fIFortran\fR, which
has comments that start with \f(CW\*(C`!\*(C'\fR, and end at the end of the line.
The pattern for this is given by \f(CW$RE{Fortran}\fR. Fixed form \fIFortran\fR,
which has been obsoleted, has comments that start with \f(CW\*(C`C\*(C'\fR, \f(CW\*(C`c\*(C'\fR or
\&\f(CW\*(C`*\*(C'\fR in the first column, or with \f(CW\*(C`!\*(C'\fR anywhere, but the sixth column.
The pattern for this are given by \f(CW$RE{Fortran}{fixed}\fR.
.Sp
See also <http://www.cray.com/craydoc/manuals/007\-3692\-005/html\-007\-3692\-005/>.
.IP "Funge\-98" 4
.IX Item "Funge-98"
The esotoric language \fIFunge\-98\fR uses comments that start and end with
a \f(CW\*(C`;\*(C'\fR.
.IP "fvwm2" 4
.IX Item "fvwm2"
Configuration files for \fIfvwm2\fR have comments starting with a
\&\f(CW\*(C`#\*(C'\fR and lasting the rest of the line.
.IP "Haifu" 4
.IX Item "Haifu"
\&\fIHaifu\fR, an esotoric language using haikus, has comments starting and
ending with a \f(CW\*(C`,\*(C'\fR.
See <http://www.dangermouse.net/esoteric/haifu.html>.
.IP "Haskell" 4
.IX Item "Haskell"
There are two types of comments in \fIHaskell\fR. They either start with
at least two dashes, or are nested comments, delimited with \f(CW\*(C`{\-\*(C'\fR and \f(CW\*(C`\-}\*(C'\fR.
Under \f(CW\*(C`{\-keep}\*(C'\fR, only \f(CW$1\fR will be set, returning the entire comment.
This pattern requires \fIperl 5.6.0\fR or newer.
.IP "\s-1HTML\s0" 4
.IX Item "HTML"
In \fI\s-1HTML\s0\fR, comments only appear inside a \fIcomment declaration\fR.
A comment declaration starts with a \f(CW\*(C`<!\*(C'\fR, and ends with a
\&\f(CW\*(C`>\*(C'\fR. Inside this declaration, we have zero or more comments.
Comments starts with \f(CW\*(C`\-\-\*(C'\fR and end with \f(CW\*(C`\-\-\*(C'\fR, and are optionally
followed by whitespace. The pattern \f(CW$RE{comment}{HTML}\fR recognizes
those comment declarations (and hence more than a comment).
Note that this is not the same as something that starts with
\&\f(CW\*(C`<!\-\-\*(C'\fR and ends with \f(CW\*(C`\-\->\*(C'\fR, because the following will
be matched completely:
.Sp
.Vb 3
\&    <!\-\-  First  Comment   \-\-
\&      \-\-> Second Comment <!\-\-
\&      \-\-  Third  Comment   \-\->
.Ve
.Sp
Do not be fooled by what your favourite browser thinks is an \s-1HTML\s0
comment.
.Sp
If \f(CW\*(C`{\-keep}\*(C'\fR is used, the following are returned:
.RS 4
.ie n .IP "$1" 4
.el .IP "\f(CW$1\fR" 4
.IX Item "$1"
captures the entire comment declaration.
.ie n .IP "$2" 4
.el .IP "\f(CW$2\fR" 4
.IX Item "$2"
captures the \s-1MDO \s0(markup declaration open), \f(CW\*(C`<!\*(C'\fR.
.ie n .IP "$3" 4
.el .IP "\f(CW$3\fR" 4
.IX Item "$3"
captures the content between the \s-1MDO\s0 and the \s-1MDC.\s0
.ie n .IP "$4" 4
.el .IP "\f(CW$4\fR" 4
.IX Item "$4"
captures the (last) comment, without the surrounding dashes.
.ie n .IP "$5" 4
.el .IP "\f(CW$5\fR" 4
.IX Item "$5"
captures the \s-1MDC \s0(markup declaration close), \f(CW\*(C`>\*(C'\fR.
.RE
.RS 4
.RE
.IP "Hugo" 4
.IX Item "Hugo"
There are two types of comments in \fIHugo\fR. They either start with
\&\f(CW\*(C`!\*(C'\fR (which cannot be followed by a \f(CW\*(C`\e\*(C'\fR), or are nested comments,
delimited with \f(CW\*(C`!\e\*(C'\fR and \f(CW\*(C`\e!\*(C'\fR.
Under \f(CW\*(C`{\-keep}\*(C'\fR, only \f(CW$1\fR will be set, returning the entire comment.
This pattern requires \fIperl 5.6.0\fR or newer.
.IP "Icon" 4
.IX Item "Icon"
\&\fIIcon\fR has comments that start with \f(CW\*(C`#\*(C'\fR and end at the next new line.
See <http://www.toolsofcomputing.com/IconHandbook/IconHandbook.pdf>,
<http://www.cs.arizona.edu/icon/index.htm>, and
<http://burks.bton.ac.uk/burks/language/icon/index.htm>.
.IP "\s-1ILLGOL\s0" 4
.IX Item "ILLGOL"
The esotoric language \fI\s-1ILLGOL\s0\fR uses comments starting with \fI\s-1NB\s0\fR and lasting
till the end of the line.
See <http://www.catseye.mb.ca/esoteric/illgol/index.html>.
.IP "\s-1INTERCAL\s0" 4
.IX Item "INTERCAL"
Comments in \s-1INTERCAL\s0 are single line comments. They start with one of
the keywords \f(CW\*(C`NOT\*(C'\fR or \f(CW\*(C`N\*(AqT\*(C'\fR, and can optionally be preceded by the
keywords \f(CW\*(C`DO\*(C'\fR and \f(CW\*(C`PLEASE\*(C'\fR. If both keywords are used, \f(CW\*(C`PLEASE\*(C'\fR
precedes \f(CW\*(C`DO\*(C'\fR. Keywords are separated by whitespace.
.IP "J" 4
.IX Item "J"
The language \fIJ\fR uses comments that start with \f(CW\*(C`NB.\*(C'\fR, and that last till
the end of the line. See
<http://www.jsoftware.com/books/help/primer/contents.htm>, and
<http://www.jsoftware.com/>.
.IP "Java" 4
.IX Item "Java"
The \fIJava\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment.
.IP "JavaDoc" 4
.IX Item "JavaDoc"
The \fIJavadoc\fR documentation syntax is demarked with a subset of
ordinary Java comments to separate it from code.  Comments start with
\&\f(CW\*(C`/**\*(C'\fR end with \f(CW\*(C`*/\*(C'\fR.  If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be set,
and set to the entire comment. See
<http://www.oracle.com/technetwork/java/javase/documentation/index\-137868.html#format>.
.IP "JavaScript" 4
.IX Item "JavaScript"
The \fIJavaScript\fR language has two forms of comments. Comments that start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, and comments that start with
\&\f(CW\*(C`/*\*(C'\fR, and end with \f(CW\*(C`*/\*(C'\fR. If \f(CW\*(C`{\-keep}\*(C'\fR is used, only \f(CW$1\fR will be
set, and set to the entire comment. \fIJavaScript\fR is Netscapes implementation
of \fIECMAScript\fR.
See <http://www.mozilla.org/js/language/E262\-3.pdf>,
and <http://www.mozilla.org/js/language/>.
.IP "LaTeX" 4
.IX Item "LaTeX"
The documentation language \fILaTeX\fR uses comments starting with \f(CW\*(C`%\*(C'\fR
and ending at the end of the line.
.IP "Lisp" 4
.IX Item "Lisp"
Comments in \fILisp\fR start with a semi-colon (\f(CW\*(C`;\*(C'\fR) and last till the
end of the line.
.IP "\s-1LPC\s0" 4
.IX Item "LPC"
The \fI\s-1LPC\s0\fR language has comments starting with \f(CW\*(C`/*\*(C'\fR and ending with \f(CW\*(C`*/\*(C'\fR.
.IP "\s-1LOGO\s0" 4
.IX Item "LOGO"
Comments for the language \fI\s-1LOGO\s0\fR start with \f(CW\*(C`;\*(C'\fR, and last till the end
of the line.
.IP "lua" 4
.IX Item "lua"
Comments for the \fIlua\fR language start with \f(CW\*(C`\-\-\*(C'\fR, and last till the end
of the line. See also <http://www.lua.org/manual/manual.html>.
.IP "M, \s-1MUMPS\s0" 4
.IX Item "M, MUMPS"
In \f(CW\*(C`M\*(C'\fR (aka \f(CW\*(C`MUMPS\*(C'\fR), comments start with a semi-colon, and last
till the end of a line. The language specification requires the 
semi-colon to be preceded by one or more \fIlinestart character\fRs.
Those characters default to a space, but that's configurable. This
requirement, of preceding the comment with linestart characters is
\&\fBnot\fR tested for. See
<ftp://ftp.intersys.com/pub/openm/ism/ism64docs.zip>,
<http://mtechnology.intersys.com/mproducts/openm/index.html>, and
<http://mcenter.com/mtrc/index.html>.
.IP "m4" 4
.IX Item "m4"
By default, the preprocessor language \fIm4\fR uses single line comments,
that start with a \f(CW\*(C`#\*(C'\fR and continue to the end of the line, including
the newline. The pattern \f(CW\*(C`$RE {comment} {m4}\*(C'\fR matches such comments.
In \fIm4\fR, it is possible to change the starting token though.
See <http://wolfram.schneider.org/bsd/7thEdManVol2/m4/m4.pdf>,
<http://www.cs.stir.ac.uk/~kjt/research/pdf/expl\-m4.pdf>, and
<http://www.gnu.org/software/m4/manual/>.
.IP "Modula\-2" 4
.IX Item "Modula-2"
In \f(CW\*(C`Modula\-2\*(C'\fR, comments start with \f(CW\*(C`(*\*(C'\fR, and end with \f(CW\*(C`*)\*(C'\fR. Comments
may be nested. See <http://www.modula2.org/>.
.IP "Modula\-3" 4
.IX Item "Modula-3"
In \f(CW\*(C`Modula\-3\*(C'\fR, comments start with \f(CW\*(C`(*\*(C'\fR, and end with \f(CW\*(C`*)\*(C'\fR. Comments
may be nested. See <http://www.m3.org/>.
.IP "mutt" 4
.IX Item "mutt"
Configuration files for \fImutt\fR have comments starting with a
\&\f(CW\*(C`#\*(C'\fR and lasting the rest of the line.
.IP "Nickle" 4
.IX Item "Nickle"
The \fINickle\fR language has one line comments starting with \f(CW\*(C`#\*(C'\fR
(like Perl), or multiline comments delimited by \f(CW\*(C`/*\*(C'\fR and \f(CW\*(C`*/\*(C'\fR
(like C). Under \f(CW\*(C`\-keep\*(C'\fR, only \f(CW$1\fR will be set. See also
<http://www.nickle.org>.
.IP "Oberon" 4
.IX Item "Oberon"
Comments in \fIOberon\fR start with \f(CW\*(C`(*\*(C'\fR and end with \f(CW\*(C`*)\*(C'\fR.
See <http://www.oberon.ethz.ch/oreport.html>.
.IP "Pascal" 4
.IX Item "Pascal"
There are many implementations of Pascal. This modules provides
pattern for comments of several implementations.
.RS 4
.ie n .IP "$RE{comment}{Pascal}" 4
.el .IP "\f(CW$RE{comment}{Pascal}\fR" 4
.IX Item "$RE{comment}{Pascal}"
This is the pattern that recognizes comments according to the Pascal \s-1ISO \s0
standard. This standard says that comments start with either \f(CW\*(C`{\*(C'\fR, or
\&\f(CW\*(C`(*\*(C'\fR, and end with \f(CW\*(C`}\*(C'\fR or \f(CW\*(C`*)\*(C'\fR. This means that \f(CW\*(C`{*)\*(C'\fR and \f(CW\*(C`(*}\*(C'\fR
are considered to be comments. Many Pascal applications don't allow this.
See <http://www.pascal\-central.com/docs/iso10206.txt>
.ie n .IP "$RE{comment}{Pascal}{Alice}" 4
.el .IP "\f(CW$RE{comment}{Pascal}{Alice}\fR" 4
.IX Item "$RE{comment}{Pascal}{Alice}"
The \fIAlice Pascal\fR compiler accepts comments that start with \f(CW\*(C`{\*(C'\fR
and end with \f(CW\*(C`}\*(C'\fR. Comments are not allowed to contain newlines.
See <http://www.templetons.com/brad/alice/language/>.
.ie n .IP "$RE{comment}{Pascal}{Delphi}, $RE{comment}{Pascal}{Free} and $RE{comment}{Pascal}{GPC}" 4
.el .IP "\f(CW$RE{comment}{Pascal}{Delphi}\fR, \f(CW$RE{comment}{Pascal}{Free}\fR and \f(CW$RE{comment}{Pascal}{GPC}\fR" 4
.IX Item "$RE{comment}{Pascal}{Delphi}, $RE{comment}{Pascal}{Free} and $RE{comment}{Pascal}{GPC}"
The \fIDelphi Pascal\fR, \fIFree Pascal\fR and the \fIGnu Pascal Compiler\fR
implementations of Pascal all have comments that either start with
\&\f(CW\*(C`//\*(C'\fR and last till the end of the line, are delimited with \f(CW\*(C`{\*(C'\fR
and \f(CW\*(C`}\*(C'\fR or are delimited with \f(CW\*(C`(*\*(C'\fR and \f(CW\*(C`*)\*(C'\fR. Patterns for those
comments are given by \f(CW$RE{comment}{Pascal}{Delphi}\fR, 
\&\f(CW$RE{comment}{Pascal}{Free}\fR and \f(CW$RE{comment}{Pascal}{GPC}\fR
respectively. These patterns only set \f(CW$1\fR when \f(CW\*(C`{\-keep}\*(C'\fR is used,
which will then include the entire comment.
.Sp
See <http://info.borland.com/techpubs/delphi5/oplg/>, 
<http://www.freepascal.org/docs\-html/ref/ref.html> and
<http://www.gnu\-pascal.de/gpc/>.
.ie n .IP "$RE{comment}{Pascal}{Workshop}" 4
.el .IP "\f(CW$RE{comment}{Pascal}{Workshop}\fR" 4
.IX Item "$RE{comment}{Pascal}{Workshop}"
The \fIWorkshop Pascal\fR compiler, from \s-1SUN\s0 Microsystems, allows comments
that are delimited with either \f(CW\*(C`{\*(C'\fR and \f(CW\*(C`}\*(C'\fR, delimited with
\&\f(CW\*(C`(*)\*(C'\fR and \f(CW\*(C`*\*(C'\fR), delimited with \f(CW\*(C`/*\*(C'\fR, and \f(CW\*(C`*/\*(C'\fR, or starting
and ending with a double quote (\f(CW\*(C`"\*(C'\fR). When \f(CW\*(C`{\-keep}\*(C'\fR is used,
only \f(CW$1\fR is set, and returns the entire comment.
.Sp
See <http://docs.sun.com/db/doc/802\-5762>.
.RE
.RS 4
.RE
.IP "\s-1PEARL\s0" 4
.IX Item "PEARL"
Comments in \fI\s-1PEARL\s0\fR start with a \f(CW\*(C`!\*(C'\fR and last till the end of the
line, or start with \f(CW\*(C`/*\*(C'\fR and end with \f(CW\*(C`*/\*(C'\fR. With \f(CW\*(C`{\-keep}\*(C'\fR, 
\&\f(CW$1\fR will be set to the entire comment.
.IP "\s-1PHP\s0" 4
.IX Item "PHP"
Comments in \fI\s-1PHP\s0\fR start with either \f(CW\*(C`#\*(C'\fR or \f(CW\*(C`//\*(C'\fR and last till the
end of the line, or are delimited by \f(CW\*(C`/*\*(C'\fR and \f(CW\*(C`*/\*(C'\fR. With \f(CW\*(C`{\-keep}\*(C'\fR,
\&\f(CW$1\fR will be set to the entire comment.
.IP "\s-1PL/B\s0" 4
.IX Item "PL/B"
In \fI\s-1PL/B\s0\fR, comments start with either \f(CW\*(C`.\*(C'\fR or \f(CW\*(C`;\*(C'\fR, and end with the 
next newline. See <http://www.mmcctech.com/pl\-b/plb\-0010.htm>.
.IP "\s-1PL/I\s0" 4
.IX Item "PL/I"
The \fI\s-1PL/I\s0\fR language has comments starting with \f(CW\*(C`/*\*(C'\fR and ending with \f(CW\*(C`*/\*(C'\fR.
.IP "\s-1PL/SQL\s0" 4
.IX Item "PL/SQL"
In \fI\s-1PL/SQL\s0\fR, comments either start with \f(CW\*(C`\-\-\*(C'\fR and run till the end
of the line, or start with \f(CW\*(C`/*\*(C'\fR and end with \f(CW\*(C`*/\*(C'\fR.
.IP "Perl" 4
.IX Item "Perl"
\&\fIPerl\fR uses comments that start with a \f(CW\*(C`#\*(C'\fR, and continue till the end
of the line.
.IP "Portia" 4
.IX Item "Portia"
The \fIPortia\fR programming language has comments that start with \f(CW\*(C`//\*(C'\fR,
and last till the end of the line.
.IP "Python" 4
.IX Item "Python"
\&\fIPython\fR uses comments that start with a \f(CW\*(C`#\*(C'\fR, and continue till the end
of the line.
.IP "Q\-BAL" 4
.IX Item "Q-BAL"
Comments in the \fIQ\-BAL\fR language start with \f(CW\*(C`\`\*(C'\fR (a backtick), and
contine till the end of the line.
.IP "\s-1QML\s0" 4
.IX Item "QML"
In \f(CW\*(C`QML\*(C'\fR, comments start with \f(CW\*(C`#\*(C'\fR and last till the end of the line.
See <http://www.questionmark.com/uk/qml/overview.doc>.
.IP "R" 4
.IX Item "R"
The statistical language \fIR\fR uses comments that start with a \f(CW\*(C`#\*(C'\fR and
end with the following new line. See <http://www.r\-project.org/>.
.IP "\s-1REBOL\s0" 4
.IX Item "REBOL"
Comments for the \fI\s-1REBOL\s0\fR language start with \f(CW\*(C`;\*(C'\fR and last till the
end of the line.
.IP "Ruby" 4
.IX Item "Ruby"
Comments in \fIRuby\fR start with \f(CW\*(C`#\*(C'\fR and last till the end of the time.
.IP "Scheme" 4
.IX Item "Scheme"
\&\fIScheme\fR comments start with \f(CW\*(C`;\*(C'\fR, and last till the end of the line.
See <http://schemers.org/>.
.IP "shell" 4
.IX Item "shell"
Comments in various \fIshell\fRs start with a \f(CW\*(C`#\*(C'\fR and end at the end of
the line.
.IP "Shelta" 4
.IX Item "Shelta"
The esotoric language \fIShelta\fR uses comments that start and end with
a \f(CW\*(C`;\*(C'\fR. See <http://www.catseye.mb.ca/esoteric/shelta/index.html>.
.IP "\s-1SLIDE\s0" 4
.IX Item "SLIDE"
The \fI\s-1SLIDE\s0\fR language has two froms of comments. First there is the
line comment, which starts with a \f(CW\*(C`#\*(C'\fR and includes the rest of the
line (just like Perl). Second, there is the multiline, nested comment,
which are delimited by \f(CW\*(C`(*\*(C'\fR and \f(CW\*(C`*)\*(C'\fR. Under C{\-keep}>, only 
\&\f(CW$1\fR is set, and is set to the entire comment. See
<http://www.cs.berkeley.edu/~ug/slide/docs/slide/spec/spec_frame_intro.shtml>.
.IP "slrn" 4
.IX Item "slrn"
Configuration files for \fIslrn\fR have comments starting with a
\&\f(CW\*(C`%\*(C'\fR and lasting the rest of the line.
.IP "Smalltalk" 4
.IX Item "Smalltalk"
\&\fISmalltalk\fR uses comments that start and end with a double quote, \f(CW\*(C`"\*(C'\fR.
.IP "\s-1SMITH\s0" 4
.IX Item "SMITH"
Comments in the \fI\s-1SMITH\s0\fR language start with \f(CW\*(C`;\*(C'\fR, and last till the
end of the line.
.IP "Squeak" 4
.IX Item "Squeak"
In the Smalltalk variant \fISqueak\fR, comments start and end with
\&\f(CW\*(C`"\*(C'\fR. Double quotes can appear inside comments by doubling them.
.IP "\s-1SQL\s0" 4
.IX Item "SQL"
Standard \fI\s-1SQL\s0\fR uses comments starting with two or more dashes, and
ending at the end of the line.
.Sp
\&\fIMySQL\fR does not follow the standard. Instead, it allows comments
that start with a \f(CW\*(C`#\*(C'\fR or \f(CW\*(C`\-\- \*(C'\fR (that's two dashes and a space)
ending with the following newline, and comments starting with 
\&\f(CW\*(C`/*\*(C'\fR, and ending with the next \f(CW\*(C`;\*(C'\fR or \f(CW\*(C`*/\*(C'\fR that isn't inside
single or double quotes. A pattern for this is returned by
\&\f(CW$RE{comment}{SQL}{MySQL}\fR. With \f(CW\*(C`{\-keep}\*(C'\fR, only \f(CW$1\fR will
be set, and it returns the entire comment.
.IP "Tcl" 4
.IX Item "Tcl"
In \fITcl\fR, comments start with \f(CW\*(C`#\*(C'\fR and continue till the end of the line.
.IP "TeX" 4
.IX Item "TeX"
The documentation language \fITeX\fR uses comments starting with \f(CW\*(C`%\*(C'\fR
and ending at the end of the line.
.IP "troff" 4
.IX Item "troff"
The document formatting language \fItroff\fR uses comments starting
with \f(CW\*(C`\e"\*(C'\fR, and continuing till the end of the line.
.IP "Ubercode" 4
.IX Item "Ubercode"
The Windows programming language \fIUbercode\fR uses comments that start with
\&\f(CW\*(C`//\*(C'\fR and continue to the end of the line. See <http://www.ubercode.com>.
.IP "vi" 4
.IX Item "vi"
In configuration files for the editor \fIvi\fR, one can use comments
starting with \f(CW\*(C`"\*(C'\fR, and ending at the end of the line.
.IP "*W" 4
.IX Item "*W"
In the language \fI*W\fR, comments start with \f(CW\*(C`||\*(C'\fR, and end with \f(CW\*(C`!!\*(C'\fR.
.IP "zonefile" 4
.IX Item "zonefile"
Comments in \s-1DNS \s0\fIzonefile\fRs start with \f(CW\*(C`;\*(C'\fR, and continue till the
end of the line.
.IP "ZZT-OOP" 4
.IX Item "ZZT-OOP"
The in-game language \fIZZT-OOP\fR uses comments that start with a \f(CW\*(C`\*(Aq\*(C'\fR 
character, and end at the following newline. See
<http://dave2.rocketjump.org/rad/zzthelp/lang.html>.
.SH "REFERENCES"
.IX Header "REFERENCES"
.IP "\fB[Go 90]\fR" 4
.IX Item "[Go 90]"
Charles F. Goldfarb: \fIThe \s-1SGML\s0 Handbook\fR. Oxford: Oxford University
Press. \fB1990\fR. \s-1ISBN 0\-19\-853737\-9.\s0 Ch. 10.3, pp 390\-391.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Regexp::Common for a general description of how to use this interface.
.SH "AUTHOR"
.IX Header "AUTHOR"
Damian Conway (damian@conway.org)
.SH "MAINTENANCE"
.IX Header "MAINTENANCE"
This package is maintained by Abigail (\fIregexp\-common@abigail.be\fR).
.SH "BUGS AND IRRITATIONS"
.IX Header "BUGS AND IRRITATIONS"
Bound to be plenty.
.PP
For a start, there are many common regexes missing.
Send them in to \fIregexp\-common@abigail.be\fR.
.SH "LICENSE and COPYRIGHT"
.IX Header "LICENSE and COPYRIGHT"
This software is Copyright (c) 2001 \- 2017, Damian Conway and Abigail.
.PP
This module is free software, and maybe used under any of the following
licenses:
.PP
.Vb 4
\& 1) The Perl Artistic License.     See the file COPYRIGHT.AL.
\& 2) The Perl Artistic License 2.0. See the file COPYRIGHT.AL2.
\& 3) The BSD License.               See the file COPYRIGHT.BSD.
\& 4) The MIT License.               See the file COPYRIGHT.MIT.
.Ve