From bdd51286dba5a9a0f8bc1f7fda654a6df83b40e7 Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Wed, 15 Oct 2025 20:26:20 +0900
Subject: [PATCH 1/6] circleci,comment: fix a typo

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---
 circle.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/circle.yml b/circle.yml
index a308171273..78911df7f1 100644
--- a/circle.yml
+++ b/circle.yml
@@ -26,7 +26,7 @@ jobs:
              # These are for input-validation.
              dnf -y install g++ jq puppet nodejs gcc-gfortran gcc-gnat typescript
              # nodejs requires libsqlite.so.0 with sqlite-session feature
-             # It was tured off in 3.46.1-1.
+             # It was turned off in 3.46.1-1.
              dnf -y update sqlite-libs
        - run:
            name: Build

From 82e75fc9dfd497961e3e3627207c965882f9d3e0 Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Sun, 18 May 2025 10:06:15 +0900
Subject: [PATCH 2/6] tokeninfo: add a function for skipping to one of multiple
 types

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---
 main/tokeninfo.c | 28 ++++++++++++++++++++++++++++
 main/tokeninfo.h |  5 +++++
 2 files changed, 33 insertions(+)

diff --git a/main/tokeninfo.c b/main/tokeninfo.c
index e3a20c676d..4166c50786 100644
--- a/main/tokeninfo.c
+++ b/main/tokeninfo.c
@@ -190,6 +190,34 @@ static int tokenGetRightSideOfPair (tokenInfo *token)
 	return token->klass->typeForUndefined;
 }
 
+static bool tokenTypeIsIn (tokenInfo *token, tokenType ts[], size_t count)
+{
+	tokenType t = token->type;
+
+	for (size_t i = 0; i < count; i++)
+	{
+		if (t == ts[i])
+			return true;
+	}
+	return false;
+}
+
+bool tokenSkipToOneOfTypesImpl (tokenInfo *token, bool skipPair, tokenType ts[], size_t count)
+{
+	while (! tokenIsEOF (token))
+	{
+		if (tokenTypeIsIn (token, ts, count))
+			return true;
+		if (skipPair &&
+			tokenGetRightSideOfPair (token) != token->klass->typeForUndefined)
+			tokenSkipOverPair (token);
+		else
+			tokenReadFull (token, NULL);
+	}
+
+	return false;
+}
+
 bool tokenSkipOverPair (tokenInfo *token)
 {
 	return tokenSkipOverPairFull(token, NULL);
diff --git a/main/tokeninfo.h b/main/tokeninfo.h
index b860dac828..3bf37f20c6 100644
--- a/main/tokeninfo.h
+++ b/main/tokeninfo.h
@@ -99,6 +99,11 @@ void tokenCopy       (tokenInfo *dest, tokenInfo *src);
    return false if it reaches EOF. */
 bool tokenSkipToType (tokenInfo *token, tokenType t);
 bool tokenSkipToTypeFull (tokenInfo *token, tokenType t, void *data);
+
+#define tokenSkipToOneOfTypes(TOKEN, SKIPPAIR, ...)						\
+	tokenSkipToOneOfTypesImpl(TOKEN, SKIPPAIR, ((tokenType []){__VA_ARGS__}), sizeof((tokenType []){__VA_ARGS__})/sizeof(tokenType))
+bool tokenSkipToOneOfTypesImpl (tokenInfo *token, bool skipPair, tokenType ts[], size_t count);
+
 bool tokenSkipOverPair (tokenInfo *token);
 bool tokenSkipOverPairFull (tokenInfo *token, void *data);
 

From 830b8e9e51860350028ebef7b1db110e5bc2f143 Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Sun, 18 May 2025 10:07:01 +0900
Subject: [PATCH 3/6] tokeninfo: add functions making tag from token directly

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---
 main/tokeninfo.c | 29 +++++++++++++++++++++++++++++
 main/tokeninfo.h |  5 +++++
 2 files changed, 34 insertions(+)

diff --git a/main/tokeninfo.c b/main/tokeninfo.c
index 4166c50786..380811d80a 100644
--- a/main/tokeninfo.c
+++ b/main/tokeninfo.c
@@ -244,3 +244,32 @@ bool tokenSkipOverPairFull (tokenInfo *token, void *data)
 
 	return (depth == 0)? true: false;
 }
+
+void tokenInitTagEntry (tokenInfo *token, tagEntryInfo *e, int kind)
+{
+	initTagEntry (e, tokenString (token), kind);
+	e->lineNumber = token->lineNumber;
+	e->filePosition = token->filePosition;
+}
+
+void tokenInitRefTagEntry (tokenInfo *token, tagEntryInfo *e, int kind, int role)
+{
+	initRefTagEntry (e, tokenString (token), kind, role);
+	e->lineNumber = token->lineNumber;
+	e->filePosition = token->filePosition;
+}
+
+int tokenMakeSimpleTag (tokenInfo *token, int kind)
+{
+	tagEntryInfo e;
+
+	tokenInitTagEntry (token, &e, kind);
+	return makeTagEntry (&e);
+}
+
+int tokenMakeSimpleRefTag (tokenInfo *token, int kind, int role)
+{
+	tagEntryInfo e;
+	tokenInitRefTagEntry (token, &e, kind, role);
+	return makeTagEntry (&e);
+}
diff --git a/main/tokeninfo.h b/main/tokeninfo.h
index 3bf37f20c6..9c840d4e10 100644
--- a/main/tokeninfo.h
+++ b/main/tokeninfo.h
@@ -107,4 +107,9 @@ bool tokenSkipToOneOfTypesImpl (tokenInfo *token, bool skipPair, tokenType ts[],
 bool tokenSkipOverPair (tokenInfo *token);
 bool tokenSkipOverPairFull (tokenInfo *token, void *data);
 
+void tokenInitTagEntry (tokenInfo *token, tagEntryInfo *e, int kind);
+void tokenInitRefTagEntry (tokenInfo *token, tagEntryInfo *e, int kind, int role);
+int tokenMakeSimpleTag (tokenInfo *token, int kind);
+int tokenMakeSimpleRefTag (tokenInfo *token, int kind, int role);
+
 #endif

From bd7e2caced7d37e546b028c4497877c82cb41b27 Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Thu, 15 May 2025 05:10:34 +0900
Subject: [PATCH 4/6] main: add a way to limit the number of lines in tasting

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---
 main/selectors.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/main/selectors.c b/main/selectors.c
index 333e94c12b..6960cd46ba 100644
--- a/main/selectors.c
+++ b/main/selectors.c
@@ -21,6 +21,7 @@
 #include "mio.h"
 
 static const char *TR_UNKNOWN = NULL;
+static const char *TR_BREAK   = "/BREAK/";
 static const char *TR_PERL5	  = "Perl";
 static const char *TR_PERL6	  = "Perl6";
 
@@ -53,6 +54,8 @@ static const char *selectByLines (MIO *input,
 	char line[0x800];
 	while (mio_gets(input, line, sizeof(line))) {
 		const char *lang = lineTaster (line, userData);
+		if (lang == TR_BREAK)
+			return defaultLang;
 		if (lang)
 			return lang;
 	}

From 5ac8417e8ef8dcc37011753c0cf3a04ad8ec6d57 Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Wed, 14 May 2025 09:06:32 +0900
Subject: [PATCH 5/6] Prolog: new parser

Close #2628.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---
 Tmain/extras-long.d/stdout-expected.txt       |   5 +
 Tmain/list-extras.d/stdout-expected.txt       |   2 +
 .../stdout-expected.txt                       |   1 +
 Tmain/list-fields.d/stdout-expected.txt       |   1 +
 Tmain/list-params.d/stdout-expected.txt       |  27 +-
 Tmain/list-roles.d/stdout-expected.txt        |   2 +
 Units/parser-prolog.r/code.d/args.ctags       |   4 +
 Units/parser-prolog.r/code.d/expected.tags    |  12 +
 Units/parser-prolog.r/code.d/input.pl         | 108 +++
 Units/parser-prolog.r/dcg.d/args.ctags        |   3 +
 Units/parser-prolog.r/dcg.d/expected.tags     |  18 +
 Units/parser-prolog.r/dcg.d/input.pl          |  93 +++
 Units/parser-prolog.r/module.d/args.ctags     |   4 +
 Units/parser-prolog.r/module.d/expected.tags  |  33 +
 Units/parser-prolog.r/module.d/input.pl       | 127 +++
 .../simple-flat-comment.d/args.ctags          |   4 +
 .../simple-flat-comment.d/expected.tags       |  28 +
 .../simple-flat-comment.d/input.pl            |  28 +
 Units/parser-prolog.r/simple.d/args.ctags     |   4 +
 Units/parser-prolog.r/simple.d/expected.tags  |  28 +
 Units/parser-prolog.r/simple.d/input.pl       |  28 +
 docs/news/HEAD.rst                            |   1 +
 main/parsers_p.h                              |   1 +
 main/selectors.c                              |  60 ++
 main/selectors.h                              |   3 +
 parsers/perl.c                                |   6 +-
 parsers/prolog.c                              | 730 ++++++++++++++++++
 source.mak                                    |   1 +
 win32/ctags_vs2013.vcxproj                    |   1 +
 win32/ctags_vs2013.vcxproj.filters            |   3 +
 30 files changed, 1352 insertions(+), 14 deletions(-)
 create mode 100644 Units/parser-prolog.r/code.d/args.ctags
 create mode 100644 Units/parser-prolog.r/code.d/expected.tags
 create mode 100644 Units/parser-prolog.r/code.d/input.pl
 create mode 100644 Units/parser-prolog.r/dcg.d/args.ctags
 create mode 100644 Units/parser-prolog.r/dcg.d/expected.tags
 create mode 100644 Units/parser-prolog.r/dcg.d/input.pl
 create mode 100644 Units/parser-prolog.r/module.d/args.ctags
 create mode 100644 Units/parser-prolog.r/module.d/expected.tags
 create mode 100644 Units/parser-prolog.r/module.d/input.pl
 create mode 100644 Units/parser-prolog.r/simple-flat-comment.d/args.ctags
 create mode 100644 Units/parser-prolog.r/simple-flat-comment.d/expected.tags
 create mode 100644 Units/parser-prolog.r/simple-flat-comment.d/input.pl
 create mode 100644 Units/parser-prolog.r/simple.d/args.ctags
 create mode 100644 Units/parser-prolog.r/simple.d/expected.tags
 create mode 100644 Units/parser-prolog.r/simple.d/input.pl
 create mode 100644 parsers/prolog.c

diff --git a/Tmain/extras-long.d/stdout-expected.txt b/Tmain/extras-long.d/stdout-expected.txt
index 383ce79d9e..e3abd50559 100644
--- a/Tmain/extras-long.d/stdout-expected.txt
+++ b/Tmain/extras-long.d/stdout-expected.txt
@@ -15,6 +15,7 @@ z       nulltag             no      NONE        no      1 Include tags with empt
 -       configPrefixed      yes     Kconfig     no      0 prepend CONFIG_ to config names
 -       CppDef              no      Make        no      1 Include FOO in -DFOO as as a name of CPreProcessor macro
 -       guessedFromFileName yes     PkgConfig   no      0 the guessed package name of the .pc file
+-       arityAppended       yes     Prolog      no      0 Include predicates with their arities
 -       funcmap             yes     QemuHX      no      0 Include mapping SQMP to C function name
 -       whitespaceSwapped   yes     Robot       no      0 Include tags swapping whitespace and underscore chars
 # enabling 1
@@ -34,6 +35,7 @@ z       nulltag             no      NONE        no      1 Include tags with empt
 -       configPrefixed      yes     Kconfig     no      0 prepend CONFIG_ to config names
 -       CppDef              no      Make        no      1 Include FOO in -DFOO as as a name of CPreProcessor macro
 -       guessedFromFileName yes     PkgConfig   no      0 the guessed package name of the .pc file
+-       arityAppended       yes     Prolog      no      0 Include predicates with their arities
 -       funcmap             yes     QemuHX      no      0 Include mapping SQMP to C function name
 -       whitespaceSwapped   yes     Robot       no      0 Include tags swapping whitespace and underscore chars
 # disabling 1
@@ -53,6 +55,7 @@ z       nulltag             no      NONE        no      1 Include tags with empt
 -       configPrefixed      yes     Kconfig     no      0 prepend CONFIG_ to config names
 -       CppDef              no      Make        no      1 Include FOO in -DFOO as as a name of CPreProcessor macro
 -       guessedFromFileName yes     PkgConfig   no      0 the guessed package name of the .pc file
+-       arityAppended       yes     Prolog      no      0 Include predicates with their arities
 -       funcmap             yes     QemuHX      no      0 Include mapping SQMP to C function name
 -       whitespaceSwapped   yes     Robot       no      0 Include tags swapping whitespace and underscore chars
 # combination
@@ -72,6 +75,7 @@ z       nulltag             no      NONE        no      1 Include tags with empt
 -       configPrefixed      yes     Kconfig     no      0 prepend CONFIG_ to config names
 -       CppDef              no      Make        no      1 Include FOO in -DFOO as as a name of CPreProcessor macro
 -       guessedFromFileName yes     PkgConfig   no      0 the guessed package name of the .pc file
+-       arityAppended       yes     Prolog      no      0 Include predicates with their arities
 -       funcmap             yes     QemuHX      no      0 Include mapping SQMP to C function name
 -       whitespaceSwapped   yes     Robot       no      0 Include tags swapping whitespace and underscore chars
 # combination with letters
@@ -91,5 +95,6 @@ z       nulltag             no      NONE        no      1 Include tags with empt
 -       configPrefixed      yes     Kconfig     no      0 prepend CONFIG_ to config names
 -       CppDef              no      Make        no      1 Include FOO in -DFOO as as a name of CPreProcessor macro
 -       guessedFromFileName yes     PkgConfig   no      0 the guessed package name of the .pc file
+-       arityAppended       yes     Prolog      no      0 Include predicates with their arities
 -       funcmap             yes     QemuHX      no      0 Include mapping SQMP to C function name
 -       whitespaceSwapped   yes     Robot       no      0 Include tags swapping whitespace and underscore chars
diff --git a/Tmain/list-extras.d/stdout-expected.txt b/Tmain/list-extras.d/stdout-expected.txt
index 83f9800c46..ad708c0365 100644
--- a/Tmain/list-extras.d/stdout-expected.txt
+++ b/Tmain/list-extras.d/stdout-expected.txt
@@ -15,6 +15,7 @@ z       nulltag             yes     NONE        no      1 Include tags with empt
 -       configPrefixed      yes     Kconfig     no      0 prepend CONFIG_ to config names
 -       CppDef              no      Make        no      1 Include FOO in -DFOO as as a name of CPreProcessor macro
 -       guessedFromFileName yes     PkgConfig   no      0 the guessed package name of the .pc file
+-       arityAppended       yes     Prolog      no      0 Include predicates with their arities
 -       funcmap             yes     QemuHX      no      0 Include mapping SQMP to C function name
 -       whitespaceSwapped   yes     Robot       no      0 Include tags swapping whitespace and underscore chars
 #LETTER	NAME	ENABLED	LANGUAGE	FIXED	VER	DESCRIPTION
@@ -34,6 +35,7 @@ z	nulltag	yes	NONE	no	1	Include tags with empty strings as their names
 -	configPrefixed	yes	Kconfig	no	0	prepend CONFIG_ to config names
 -	CppDef	no	Make	no	1	Include FOO in -DFOO as as a name of CPreProcessor macro
 -	guessedFromFileName	yes	PkgConfig	no	0	the guessed package name of the .pc file
+-	arityAppended	yes	Prolog	no	0	Include predicates with their arities
 -	funcmap	yes	QemuHX	no	0	Include mapping SQMP to C function name
 -	whitespaceSwapped	yes	Robot	no	0	Include tags swapping whitespace and underscore chars
 #LETTER NAME      ENABLED LANGUAGE FIXED VER DESCRIPTION
diff --git a/Tmain/list-fields-with-prefix.d/stdout-expected.txt b/Tmain/list-fields-with-prefix.d/stdout-expected.txt
index 1f37f993a7..8de8d30483 100644
--- a/Tmain/list-fields-with-prefix.d/stdout-expected.txt
+++ b/Tmain/list-fields-with-prefix.d/stdout-expected.txt
@@ -42,6 +42,7 @@ x       UCTAGSxpath          no      NONE             s--    no    --   0 xpath
 -       UCTAGSprotocols      yes     ObjectiveC       s--    no    --   0 protocols that the class (or category) confirms to
 -       UCTAGShome           yes     Passwd           s--    no    rw   0 home directory
 -       UCTAGSshell          yes     Passwd           s--    no    rw   0 login shell
+-       UCTAGSarity          yes     Prolog           -i-    no    --   0 the number of parameters
 -       UCTAGSdecorators     no      Python           s--    no    --   0 decorators on functions and classes
 -       UCTAGSnameref        yes     Python           s--    no    --   0 the original name for the tag
 -       UCTAGSassignmentop   no      R                s--    no    --   0 operator for assignment
diff --git a/Tmain/list-fields.d/stdout-expected.txt b/Tmain/list-fields.d/stdout-expected.txt
index df89b5bda4..0f0618a257 100644
--- a/Tmain/list-fields.d/stdout-expected.txt
+++ b/Tmain/list-fields.d/stdout-expected.txt
@@ -60,6 +60,7 @@ z	kind	no	NONE	s--	no	r-	0	[tags output] prepend "kind:" to k/ (or K/) field out
 -	protocols	yes	ObjectiveC	s--	no	--	0	protocols that the class (or category) confirms to
 -	home	yes	Passwd	s--	no	rw	0	home directory
 -	shell	yes	Passwd	s--	no	rw	0	login shell
+-	arity	yes	Prolog	-i-	no	--	0	the number of parameters
 -	decorators	no	Python	s--	no	--	0	decorators on functions and classes
 -	nameref	yes	Python	s--	no	--	0	the original name for the tag
 -	assignmentop	no	R	s--	no	--	0	operator for assignment
diff --git a/Tmain/list-params.d/stdout-expected.txt b/Tmain/list-params.d/stdout-expected.txt
index c2d7806b96..bb6ee857fc 100644
--- a/Tmain/list-params.d/stdout-expected.txt
+++ b/Tmain/list-params.d/stdout-expected.txt
@@ -1,16 +1,17 @@
 # ALL
-#LANGUAGE      NAME              DESCRIPTION
-Asm            commentCharsAtBOL line comment chraracters at the beginning of line ([;*@])
-Asm            commentCharsInMOL line comment chraracters in the beginning of line ([])
-Asm            extraLinesepChars extra characters used as a line separator ([])
-Asm            useCPreProcessor  run CPreProcessor parser for extracting macro definitions ([true] or false)
-CPreProcessor  _expand           expand macros if their definitions are in the current C/C++/CUDA input file (true or [false])
-CPreProcessor  define            define replacement for an identifier (name(params,...)=definition)
-CPreProcessor  if0               examine code within "#if 0" branch (true or [false])
-CPreProcessor  ignore            a token to be specially handled
-Fypp           guest             parser run after Fypp parser parses the original input ("NONE" or a parser name [Fortran])
-ITcl           forceUse          enable the parser even when `itcl' namespace is not specified in the input (true or [false])
-TclOO          forceUse          enable the parser even when `oo' namespace is not specified in the input (true or [false])
+#LANGUAGE      NAME                DESCRIPTION
+Asm            commentCharsAtBOL   line comment chraracters at the beginning of line ([;*@])
+Asm            commentCharsInMOL   line comment chraracters in the beginning of line ([])
+Asm            extraLinesepChars   extra characters used as a line separator ([])
+Asm            useCPreProcessor    run CPreProcessor parser for extracting macro definitions ([true] or false)
+CPreProcessor  _expand             expand macros if their definitions are in the current C/C++/CUDA input file (true or [false])
+CPreProcessor  define              define replacement for an identifier (name(params,...)=definition)
+CPreProcessor  if0                 examine code within "#if 0" branch (true or [false])
+CPreProcessor  ignore              a token to be specially handled
+Fypp           guest               parser run after Fypp parser parses the original input ("NONE" or a parser name [Fortran])
+ITcl           forceUse            enable the parser even when `itcl' namespace is not specified in the input (true or [false])
+Prolog         allowNestedComments allow nested comments like "/* /* */ */" ([true] or false)
+TclOO          forceUse            enable the parser even when `oo' namespace is not specified in the input (true or [false])
 
 # ALL MACHINABLE
 #LANGUAGE	NAME	DESCRIPTION
@@ -24,6 +25,7 @@ CPreProcessor	if0	examine code within "#if 0" branch (true or [false])
 CPreProcessor	ignore	a token to be specially handled
 Fypp	guest	parser run after Fypp parser parses the original input ("NONE" or a parser name [Fortran])
 ITcl	forceUse	enable the parser even when `itcl' namespace is not specified in the input (true or [false])
+Prolog	allowNestedComments	allow nested comments like "/* /* */ */" ([true] or false)
 TclOO	forceUse	enable the parser even when `oo' namespace is not specified in the input (true or [false])
 
 # ALL MACHINABLE NOHEADER
@@ -37,6 +39,7 @@ CPreProcessor	if0	examine code within "#if 0" branch (true or [false])
 CPreProcessor	ignore	a token to be specially handled
 Fypp	guest	parser run after Fypp parser parses the original input ("NONE" or a parser name [Fortran])
 ITcl	forceUse	enable the parser even when `itcl' namespace is not specified in the input (true or [false])
+Prolog	allowNestedComments	allow nested comments like "/* /* */ */" ([true] or false)
 TclOO	forceUse	enable the parser even when `oo' namespace is not specified in the input (true or [false])
 
 # CPP
diff --git a/Tmain/list-roles.d/stdout-expected.txt b/Tmain/list-roles.d/stdout-expected.txt
index aa0bdfac9c..870c799216 100644
--- a/Tmain/list-roles.d/stdout-expected.txt
+++ b/Tmain/list-roles.d/stdout-expected.txt
@@ -98,6 +98,7 @@ Perl                    h/heredoc         endmarker          on        0 end mar
 PkgConfig               p/pkg             conflicted         on        0 conflicted
 PkgConfig               p/pkg             provided           on        0 provided
 PkgConfig               p/pkg             required           on        0 required
+Prolog                  m/module          chainElt           off       0 (EXPERIMENTAL)used as an element in a module-qualified atom like module:predicate
 Protobuf                D/protodef        imported           on        0 imported
 Protobuf                m/message         extension          on        0 extending the message
 Python                  Y/unknown         imported           on        0 imported from the other module
@@ -248,6 +249,7 @@ Perl                    h/heredoc         endmarker          on        0 end mar
 PkgConfig               p/pkg             conflicted         on        0 conflicted
 PkgConfig               p/pkg             provided           on        0 provided
 PkgConfig               p/pkg             required           on        0 required
+Prolog                  m/module          chainElt           off       0 (EXPERIMENTAL)used as an element in a module-qualified atom like module:predicate
 Protobuf                D/protodef        imported           on        0 imported
 Protobuf                m/message         extension          on        0 extending the message
 Python                  Y/unknown         imported           on        0 imported from the other module
diff --git a/Units/parser-prolog.r/code.d/args.ctags b/Units/parser-prolog.r/code.d/args.ctags
new file mode 100644
index 0000000000..d93aeea872
--- /dev/null
+++ b/Units/parser-prolog.r/code.d/args.ctags
@@ -0,0 +1,4 @@
+-G
+--sort=no
+--extras=+q
+--fields=+neEK
diff --git a/Units/parser-prolog.r/code.d/expected.tags b/Units/parser-prolog.r/code.d/expected.tags
new file mode 100644
index 0000000000..f915636c8d
--- /dev/null
+++ b/Units/parser-prolog.r/code.d/expected.tags
@@ -0,0 +1,12 @@
+unicode_file_name	input.pl	/^unicode_file_name(Name) :-$/;"	predicate	line:44	end:47	arity:1
+unicode_file_name/1	input.pl	/^unicode_file_name(Name) :-$/;"	predicate	line:44	extras:arityAppended	end:47	arity:1
+unicode_file	input.pl	/^unicode_file(mkdir-1) :-                        % create Cyrillic directory$/;"	predicate	line:49	end:58	arity:1
+unicode_file/1	input.pl	/^unicode_file(mkdir-1) :-                        % create Cyrillic directory$/;"	predicate	line:49	extras:arityAppended	end:58	arity:1
+unicode_file	input.pl	/^unicode_file(file-1) :-                         % create Cyrillic file$/;"	predicate	line:59	end:71	arity:1
+unicode_file/1	input.pl	/^unicode_file(file-1) :-                         % create Cyrillic file$/;"	predicate	line:59	extras:arityAppended	end:71	arity:1
+unicode_file	input.pl	/^unicode_file(absfile-1) :-$/;"	predicate	line:72	end:78	arity:1
+unicode_file/1	input.pl	/^unicode_file(absfile-1) :-$/;"	predicate	line:72	extras:arityAppended	end:78	arity:1
+unicode_file	input.pl	/^unicode_file(ext-1) :-$/;"	predicate	line:79	end:83	arity:1
+unicode_file/1	input.pl	/^unicode_file(ext-1) :-$/;"	predicate	line:79	extras:arityAppended	end:83	arity:1
+seek	input.pl	/^seek(write-1) :-$/;"	predicate	line:90	end:108	arity:1
+seek/1	input.pl	/^seek(write-1) :-$/;"	predicate	line:90	extras:arityAppended	end:108	arity:1
diff --git a/Units/parser-prolog.r/code.d/input.pl b/Units/parser-prolog.r/code.d/input.pl
new file mode 100644
index 0000000000..e165388d98
--- /dev/null
+++ b/Units/parser-prolog.r/code.d/input.pl
@@ -0,0 +1,108 @@
+% Taken from pl-9.2.9-build/swipl-9.2.9/src/test.pl
+% 0'. can be a trouble.
+
+/*  Part of SWI-Prolog
+
+    Author:        Jan Wielemaker and Anjo Anjewierden
+    E-mail:        J.Wielemaker@cs.vu.nl
+    WWW:           http://www.swi-prolog.org
+    Copyright (c)  1996-2023, University of Amsterdam
+                              VU University Amsterdam
+                              CWI, Amsterdam
+                              SWI-Prolog Solutions b.v.
+    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.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+    CAUSED AND 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.
+*/
+                 /*******************************
+                 *      UNICODE FILENAMES       *
+                 *******************************/
+
+unicode_file_name(Name) :-
+    current_prolog_flag(pid, Pid),
+    atom_codes(Name0, [1074, 1086, 1079, 1076, 1091, 1093, 1072]),
+    atomic_list_concat([Name0, -, Pid], Name).
+
+unicode_file(mkdir-1) :-                        % create Cyrillic directory
+    unicode_file_name(Dir),
+    catch(delete_directory(Dir), _, true),
+    make_directory(Dir),
+    exists_directory(Dir),
+    working_directory(Old, Dir),
+    working_directory(O2, '..'),
+    same_file(Old, '.'),
+    same_file(O2, Dir),
+    delete_directory(Dir).
+unicode_file(file-1) :-                         % create Cyrillic file
+    unicode_file_name(File),
+    Term = hello(world),
+    catch(delete_file(File), _, true),
+    open(File, write, Out),
+    format(Out, '~q.~n', [Term]),
+    close(Out),
+    exists_file(File),
+    open(File, read, In),
+    read(In, Read),
+    close(In),
+    Read =@= Term,
+    delete_file(File).
+unicode_file(absfile-1) :-
+    unicode_file_name(File),
+    absolute_file_name(File, Path),
+    file_directory_name(Path, Dir),
+    same_file(Dir, '.'),
+    file_base_name(Path, Base),
+    Base == File.
+unicode_file(ext-1) :-
+    atom_codes(File, [1074, 1086, 1079, 1076, 0'., 1091, 1093, 1072]),
+    file_name_extension(Base, Ext, File),
+    atom_codes(Base, [1074, 1086, 1079, 1076]),
+    atom_codes(Ext, [1091, 1093, 1072]).
+
+
+                 /*******************************
+                 *              SEEK            *
+                 *******************************/
+
+seek(write-1) :-
+    tmp_file(seek, File),
+    open(File, write, S, [type(binary)]),
+    Max = 999,
+    forall(between(0, Max, _),
+           format(S, '1234567890~n', [])),
+    forall(between(0, Max, N),
+           (   Pos is N * 11 + 6,
+               seek(S, Pos, bof, _),
+               format(S, 'x', [])
+           )),
+    close(S),
+
+    open(File, read, In, [type(binary)]),
+    atom_codes('123456x890\n', Bytes),
+    forall(between(0, Max, N),
+           must_read(Bytes, In)),
+    close(In),
+    delete_file(File).
diff --git a/Units/parser-prolog.r/dcg.d/args.ctags b/Units/parser-prolog.r/dcg.d/args.ctags
new file mode 100644
index 0000000000..a47c3a8063
--- /dev/null
+++ b/Units/parser-prolog.r/dcg.d/args.ctags
@@ -0,0 +1,3 @@
+-G
+--sort=no
+--fields=+neEK
diff --git a/Units/parser-prolog.r/dcg.d/expected.tags b/Units/parser-prolog.r/dcg.d/expected.tags
new file mode 100644
index 0000000000..2445f1f7e0
--- /dev/null
+++ b/Units/parser-prolog.r/dcg.d/expected.tags
@@ -0,0 +1,18 @@
+server	input.pl	/^server :-$/;"	predicate	line:27	end:28	arity:0
+server/0	input.pl	/^server :-$/;"	predicate	line:27	extras:arityAppended	end:28	arity:0
+server	input.pl	/^server(Port, Options) :-$/;"	predicate	line:30	end:35	arity:2
+server/2	input.pl	/^server(Port, Options) :-$/;"	predicate	line:30	extras:arityAppended	end:35	arity:2
+reply	input.pl	/^reply(Request) :-$/;"	predicate	line:37	end:39	arity:1
+reply/1	input.pl	/^reply(Request) :-$/;"	predicate	line:37	extras:arityAppended	end:39	arity:1
+reply	input.pl	/^reply(\/, _Request) :-$/;"	predicate	line:41	end:45	arity:2
+reply/2	input.pl	/^reply(\/, _Request) :-$/;"	predicate	line:41	extras:arityAppended	end:45	arity:2
+reply	input.pl	/^reply('\/calc', Request) :-$/;"	predicate	line:47	end:56	arity:2
+reply/2	input.pl	/^reply('\/calc', Request) :-$/;"	predicate	line:47	extras:arityAppended	end:56	arity:2
+page	input.pl	/^page(Formula) :-$/;"	predicate	line:59	end:74	arity:1
+page/1	input.pl	/^page(Formula) :-$/;"	predicate	line:59	extras:arityAppended	end:74	arity:1
+formula	input.pl	/^formula(Formula) -->$/;"	grammar	line:76	end:80	arity:1
+formula/1	input.pl	/^formula(Formula) -->$/;"	grammar	line:76	extras:arityAppended	end:80	arity:1
+ops	input.pl	/^ops -->$/;"	grammar	line:82	end:88	arity:0
+ops/0	input.pl	/^ops -->$/;"	grammar	line:82	extras:arityAppended	end:88	arity:0
+reply_page	input.pl	/^reply_page(Title, Content) :-$/;"	predicate	line:90	end:93	arity:2
+reply_page/2	input.pl	/^reply_page(Title, Content) :-$/;"	predicate	line:90	extras:arityAppended	end:93	arity:2
diff --git a/Units/parser-prolog.r/dcg.d/input.pl b/Units/parser-prolog.r/dcg.d/input.pl
new file mode 100644
index 0000000000..0492e12948
--- /dev/null
+++ b/Units/parser-prolog.r/dcg.d/input.pl
@@ -0,0 +1,93 @@
+% Taken from swipl-9.2.9
+/*  $Id$
+
+    Part of SWI-Prolog
+
+    Author:        Jan Wielemaker
+    E-mail:        wielemak@science.uva.nl
+    WWW:           http://www.swi-prolog.org
+    Copyright (C): Public domain
+*/
+
+:- use_module(library('http/thread_httpd')).
+:- use_module(library('http/html_write')).
+:- use_module(library('http/http_session')).
+:- use_module(library('http/http_error')).
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+This demo shows session state  management   in  a very simple calculator
+package. It also demonstrates the use of  the html_write library. To use
+it, start Prolog, load this file and run
+
+        ?- server.
+
+Now direct your browser to http://localhost:3000/
+- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
+
+server :-
+    server(3000, []).
+
+server(Port, Options) :-
+    http_server(reply,
+                [ port(Port),
+                  timeout(20)
+                | Options
+                ]).
+
+reply(Request) :-
+    memberchk(path(Path), Request),
+    reply(Path, Request).
+
+reply(/, _Request) :-
+    http_session_retractall(formula(_)),
+    Formula = 0,
+    http_session_assert(formula(Formula)),
+    page(Formula).
+
+reply('/calc', Request) :-
+    memberchk(search(Search), Request),
+    memberchk(operation=Op, Search),
+    memberchk(value=AtomVal, Search),
+    atom_number(AtomVal, Val),
+    http_session_retract(formula(Formula0)),
+    debug(calc, 'Formula0 = ~w', [Formula0]),
+    Formula =.. [Op, Formula0, Val],
+    http_session_assert(formula(Formula)),
+    page(Formula).
+
+
+page(Formula) :-
+    reply_page('HTTP Session DEMO',
+               [ h2('Simple session demo'),
+                 form([ action('/calc'),
+                        method('GET')
+                      ],
+                      table([align(center), border(1)],
+                            [ tr(td(\formula(Formula))),
+                              tr(td([ \ops,
+                                      input([ name(value) ]),
+                                      input([ type(submit),
+                                              value('Calc!')
+                                            ])
+                                    ]))
+                            ]))
+               ]).
+
+formula(Formula) -->
+    { sformat(S, '~w', [Formula]),
+      Value is Formula
+    },
+    html([ S, ' = ', Value ]).
+
+ops -->
+    html(select(name(operation),
+                [ option([selected], +),
+                  option([], -),
+                  option([], /),
+                  option([], *)
+                ])).
+
+reply_page(Title, Content) :-
+    phrase(page(title(Title), Content), HTML),
+    format('Content-type: text/html~n~n'),
+    print_html(HTML).
diff --git a/Units/parser-prolog.r/module.d/args.ctags b/Units/parser-prolog.r/module.d/args.ctags
new file mode 100644
index 0000000000..d93aeea872
--- /dev/null
+++ b/Units/parser-prolog.r/module.d/args.ctags
@@ -0,0 +1,4 @@
+-G
+--sort=no
+--extras=+q
+--fields=+neEK
diff --git a/Units/parser-prolog.r/module.d/expected.tags b/Units/parser-prolog.r/module.d/expected.tags
new file mode 100644
index 0000000000..4260cfc0fe
--- /dev/null
+++ b/Units/parser-prolog.r/module.d/expected.tags
@@ -0,0 +1,33 @@
+clpq	input.pl	/^:- module(clpq,$/;"	module	line:42
+portray_message	input.pl	/^user:portray_message(warning,import(_,_,clpq,private)).$/;"	predicate	line:67	module:user	end:67	arity:2
+user:portray_message	input.pl	/^user:portray_message(warning,import(_,_,clpq,private)).$/;"	predicate	line:67	module:user	extras:qualified	end:67	arity:2
+portray_message/2	input.pl	/^user:portray_message(warning,import(_,_,clpq,private)).$/;"	predicate	line:67	module:user	extras:arityAppended	end:67	arity:2
+user:portray_message/2	input.pl	/^user:portray_message(warning,import(_,_,clpq,private)).$/;"	predicate	line:67	module:user	extras:qualified,arityAppended	end:67	arity:2
+message	input.pl	/^prolog:message(query(YesNo,Bindings)) --> !,$/;"	grammar	line:93	module:prolog	end:96	arity:1
+prolog:message	input.pl	/^prolog:message(query(YesNo,Bindings)) --> !,$/;"	grammar	line:93	module:prolog	extras:qualified	end:96	arity:1
+message/1	input.pl	/^prolog:message(query(YesNo,Bindings)) --> !,$/;"	grammar	line:93	module:prolog	extras:arityAppended	end:96	arity:1
+prolog:message/1	input.pl	/^prolog:message(query(YesNo,Bindings)) --> !,$/;"	grammar	line:93	module:prolog	extras:qualified,arityAppended	end:96	arity:1
+dump_toplevel_bindings	input.pl	/^dump_toplevel_bindings(Bindings,Constraints) :-$/;"	predicate	line:98	module:clpq	end:100	arity:2
+clpq:dump_toplevel_bindings	input.pl	/^dump_toplevel_bindings(Bindings,Constraints) :-$/;"	predicate	line:98	module:clpq	extras:qualified	end:100	arity:2
+dump_toplevel_bindings/2	input.pl	/^dump_toplevel_bindings(Bindings,Constraints) :-$/;"	predicate	line:98	module:clpq	extras:arityAppended	end:100	arity:2
+clpq:dump_toplevel_bindings/2	input.pl	/^dump_toplevel_bindings(Bindings,Constraints) :-$/;"	predicate	line:98	module:clpq	extras:qualified,arityAppended	end:100	arity:2
+dump_vars_names	input.pl	/^dump_vars_names([],_,[],[]).$/;"	predicate	line:102	module:clpq	end:102	arity:4
+clpq:dump_vars_names	input.pl	/^dump_vars_names([],_,[],[]).$/;"	predicate	line:102	module:clpq	extras:qualified	end:102	arity:4
+dump_vars_names/4	input.pl	/^dump_vars_names([],_,[],[]).$/;"	predicate	line:102	module:clpq	extras:arityAppended	end:102	arity:4
+clpq:dump_vars_names/4	input.pl	/^dump_vars_names([],_,[],[]).$/;"	predicate	line:102	module:clpq	extras:qualified,arityAppended	end:102	arity:4
+dump_vars_names	input.pl	/^dump_vars_names([Name=Term|Rest],Seen,Vars,Names) :-$/;"	predicate	line:103	module:clpq	end:116	arity:4
+clpq:dump_vars_names	input.pl	/^dump_vars_names([Name=Term|Rest],Seen,Vars,Names) :-$/;"	predicate	line:103	module:clpq	extras:qualified	end:116	arity:4
+dump_vars_names/4	input.pl	/^dump_vars_names([Name=Term|Rest],Seen,Vars,Names) :-$/;"	predicate	line:103	module:clpq	extras:arityAppended	end:116	arity:4
+clpq:dump_vars_names/4	input.pl	/^dump_vars_names([Name=Term|Rest],Seen,Vars,Names) :-$/;"	predicate	line:103	module:clpq	extras:qualified,arityAppended	end:116	arity:4
+dump_format	input.pl	/^dump_format([]) --> [].$/;"	grammar	line:118	module:clpq	end:118	arity:1
+clpq:dump_format	input.pl	/^dump_format([]) --> [].$/;"	grammar	line:118	module:clpq	extras:qualified	end:118	arity:1
+dump_format/1	input.pl	/^dump_format([]) --> [].$/;"	grammar	line:118	module:clpq	extras:arityAppended	end:118	arity:1
+clpq:dump_format/1	input.pl	/^dump_format([]) --> [].$/;"	grammar	line:118	module:clpq	extras:qualified,arityAppended	end:118	arity:1
+dump_format	input.pl	/^dump_format([X|Xs]) -->$/;"	grammar	line:119	module:clpq	end:121	arity:1
+clpq:dump_format	input.pl	/^dump_format([X|Xs]) -->$/;"	grammar	line:119	module:clpq	extras:qualified	end:121	arity:1
+dump_format/1	input.pl	/^dump_format([X|Xs]) -->$/;"	grammar	line:119	module:clpq	extras:arityAppended	end:121	arity:1
+clpq:dump_format/1	input.pl	/^dump_format([X|Xs]) -->$/;"	grammar	line:119	module:clpq	extras:qualified,arityAppended	end:121	arity:1
+memberchk_eq	input.pl	/^memberchk_eq(X,[Y|Ys]) :-$/;"	predicate	line:123	module:clpq	end:127	arity:2
+clpq:memberchk_eq	input.pl	/^memberchk_eq(X,[Y|Ys]) :-$/;"	predicate	line:123	module:clpq	extras:qualified	end:127	arity:2
+memberchk_eq/2	input.pl	/^memberchk_eq(X,[Y|Ys]) :-$/;"	predicate	line:123	module:clpq	extras:arityAppended	end:127	arity:2
+clpq:memberchk_eq/2	input.pl	/^memberchk_eq(X,[Y|Ys]) :-$/;"	predicate	line:123	module:clpq	extras:qualified,arityAppended	end:127	arity:2
diff --git a/Units/parser-prolog.r/module.d/input.pl b/Units/parser-prolog.r/module.d/input.pl
new file mode 100644
index 0000000000..e053c1f230
--- /dev/null
+++ b/Units/parser-prolog.r/module.d/input.pl
@@ -0,0 +1,127 @@
+% Taken from swipl-9.2.9
+
+/*
+
+    Part of CLP(Q) (Constraint Logic Programming over Rationals)
+
+    Author:        Leslie De Koninck
+    E-mail:        Leslie.DeKoninck@cs.kuleuven.be
+    WWW:           http://www.swi-prolog.org
+		   http://www.ai.univie.ac.at/cgi-bin/tr-online?number+95-09
+    Copyright (C): 2006, K.U. Leuven and
+		   1992-1995, Austrian Research Institute for
+		              Artificial Intelligence (OFAI),
+			      Vienna, Austria
+
+    This software is based on CLP(Q,R) by Christian Holzbaur for SICStus
+    Prolog and distributed under the license details below with permission from
+    all mentioned authors.
+
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License
+    as published by the Free Software Foundation; either version 2
+    of the License, or (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+    As a special exception, if you link this library with other files,
+    compiled with a Free Software compiler, to produce an executable, this
+    library does not by itself cause the resulting executable to be covered
+    by the GNU General Public License. This exception does not however
+    invalidate any other reasons why the executable file might be covered by
+    the GNU General Public License.
+*/
+
+:- module(clpq,
+	  [ {}/1,
+	    maximize/1,
+	    minimize/1,
+	    inf/2, inf/4, sup/2, sup/4,
+	    bb_inf/3,
+	    bb_inf/4,
+	    ordering/1,
+	    entailed/1,
+	    clp_type/2,
+	    dump/3%, projecting_assert/1
+	  ]).
+:- license(gpl_swipl, 'CLP(Q)').
+:- use_module(library(dialect)).
+:- expects_dialect(swi).
+
+%
+% Don't report export of private predicates from clpq
+%
+:- multifile
+	user:portray_message/2.
+
+:- dynamic
+	user:portray_message/2.
+%
+user:portray_message(warning,import(_,_,clpq,private)).
+
+:- use_module([ clpq/bb_q,
+		clpq/bv_q,
+		clpq/fourmotz_q,
+		clpq/ineq_q,
+		clpq/itf_q,
+		clpq/nf_q,
+		clpq/store_q,
+		clpqr/class,
+		clpqr/dump,
+		clpqr/geler,
+		clpqr/itf,
+		clpqr/ordering,
+		clpqr/project,
+		clpqr/redund,
+		library(ugraphs)
+	      ]).
+
+		 /*******************************
+		 *	 TOPLEVEL PRINTING	*
+		 *******************************/
+
+:- multifile
+	prolog:message/3.
+
+prolog:message(query(YesNo,Bindings)) --> !,
+	{dump_toplevel_bindings(Bindings,Constraints)},
+	dump_format(Constraints),
+        '$messages':prolog_message(query(YesNo,Bindings)).
+
+dump_toplevel_bindings(Bindings,Constraints) :-
+	dump_vars_names(Bindings,[],Vars,Names),
+	dump(Vars,Names,Constraints).
+
+dump_vars_names([],_,[],[]).
+dump_vars_names([Name=Term|Rest],Seen,Vars,Names) :-
+	(   var(Term),
+	    (   get_attr(Term,clpqr_itf,_)
+	    ;   get_attr(Term,clpqr_geler,_)
+	    ),
+	    \+ memberchk_eq(Term,Seen)
+	->  Vars = [Term|RVars],
+	    Names = [Name|RNames],
+	    NSeen = [Term|Seen]
+	;   Vars = RVars,
+	    Names = RNames,
+	    Seen = NSeen
+	),
+	dump_vars_names(Rest,NSeen,RVars,RNames).
+
+dump_format([]) --> [].
+dump_format([X|Xs]) -->
+	['{~w}'-[X], nl],
+	dump_format(Xs).
+
+memberchk_eq(X,[Y|Ys]) :-
+	(   X == Y
+	->  true
+	;   memberchk_eq(X,Ys)
+	).
diff --git a/Units/parser-prolog.r/simple-flat-comment.d/args.ctags b/Units/parser-prolog.r/simple-flat-comment.d/args.ctags
new file mode 100644
index 0000000000..b36a1605b9
--- /dev/null
+++ b/Units/parser-prolog.r/simple-flat-comment.d/args.ctags
@@ -0,0 +1,4 @@
+-G
+--sort=no
+--fields=+nEK
+--param-Prolog.allowNestedComments=0
diff --git a/Units/parser-prolog.r/simple-flat-comment.d/expected.tags b/Units/parser-prolog.r/simple-flat-comment.d/expected.tags
new file mode 100644
index 0000000000..c7ea8bbff1
--- /dev/null
+++ b/Units/parser-prolog.r/simple-flat-comment.d/expected.tags
@@ -0,0 +1,28 @@
+mother_child	input.pl	/^mother_child(trude, sally).$/;"	predicate	line:2	arity:2
+mother_child/2	input.pl	/^mother_child(trude, sally).$/;"	predicate	line:2	extras:arityAppended	arity:2
+father_child	input.pl	/^father_child(tom, sally).$/;"	predicate	line:4	arity:2
+father_child/2	input.pl	/^father_child(tom, sally).$/;"	predicate	line:4	extras:arityAppended	arity:2
+father_child	input.pl	/^father_child(tom, erica).$/;"	predicate	line:5	arity:2
+father_child/2	input.pl	/^father_child(tom, erica).$/;"	predicate	line:5	extras:arityAppended	arity:2
+father_child	input.pl	/^father_child(mike, tom).$/;"	predicate	line:6	arity:2
+father_child/2	input.pl	/^father_child(mike, tom).$/;"	predicate	line:6	extras:arityAppended	arity:2
+sibling	input.pl	/^sibling(X, Y)      :- parent_child(Z, X), parent_child(Z, Y).$/;"	predicate	line:8	arity:2
+sibling/2	input.pl	/^sibling(X, Y)      :- parent_child(Z, X), parent_child(Z, Y).$/;"	predicate	line:8	extras:arityAppended	arity:2
+parent_child	input.pl	/^parent_child(X, Y) :- father_child(X, Y).$/;"	predicate	line:10	arity:2
+parent_child/2	input.pl	/^parent_child(X, Y) :- father_child(X, Y).$/;"	predicate	line:10	extras:arityAppended	arity:2
+parent_child	input.pl	/^parent_child(X, Y) :- mother_child(X, Y).$/;"	predicate	line:11	arity:2
+parent_child/2	input.pl	/^parent_child(X, Y) :- mother_child(X, Y).$/;"	predicate	line:11	extras:arityAppended	arity:2
+not_dummy	input.pl	/^not_dummy.$/;"	predicate	line:16	arity:0
+not_dummy/0	input.pl	/^not_dummy.$/;"	predicate	line:16	extras:arityAppended	arity:0
+'quoted predicate'	input.pl	/^'quoted predicate'($/;"	predicate	line:18	arity:1
+'quoted predicate'/1	input.pl	/^'quoted predicate'($/;"	predicate	line:18	extras:arityAppended	arity:1
+rel	input.pl	/^rel(X,Y,Z) :- Z =:= X + Y + 0.25.$/;"	predicate	line:23	arity:3
+rel/3	input.pl	/^rel(X,Y,Z) :- Z =:= X + Y + 0.25.$/;"	predicate	line:23	extras:arityAppended	arity:3
+rel	input.pl	/^rel(X,Y) :- Y =:= X + 0.25.$/;"	predicate	line:24	arity:2
+rel/2	input.pl	/^rel(X,Y) :- Y =:= X + 0.25.$/;"	predicate	line:24	extras:arityAppended	arity:2
+rel	input.pl	/^rel(X) :- X =:= 100_000.$/;"	predicate	line:25	arity:1
+rel/1	input.pl	/^rel(X) :- X =:= 100_000.$/;"	predicate	line:25	extras:arityAppended	arity:1
+rel0	input.pl	/^rel0(X) :- X =:= 100_000 0.$/;"	predicate	line:27	arity:1
+rel0/1	input.pl	/^rel0(X) :- X =:= 100_000 0.$/;"	predicate	line:27	extras:arityAppended	arity:1
+rel0	input.pl	/^rel0(X, 100_000_11, Y) :- X =:= Y.$/;"	predicate	line:28	arity:3
+rel0/3	input.pl	/^rel0(X, 100_000_11, Y) :- X =:= Y.$/;"	predicate	line:28	extras:arityAppended	arity:3
diff --git a/Units/parser-prolog.r/simple-flat-comment.d/input.pl b/Units/parser-prolog.r/simple-flat-comment.d/input.pl
new file mode 100644
index 0000000000..160a111965
--- /dev/null
+++ b/Units/parser-prolog.r/simple-flat-comment.d/input.pl
@@ -0,0 +1,28 @@
+%% Taken from https://en.wikipedia.org/wiki/Prolog
+mother_child(trude, sally).
+
+father_child(tom, sally).
+father_child(tom, erica).
+father_child(mike, tom).
+
+sibling(X, Y)      :- parent_child(Z, X), parent_child(Z, Y).
+
+parent_child(X, Y) :- father_child(X, Y).
+parent_child(X, Y) :- mother_child(X, Y).
+
+% dummy0()
+/* dummy1() */
+/* /* dummy2() */
+not_dummy.
+
+'quoted predicate'(
+X
+) :-
+	father_child(tom, X).
+
+rel(X,Y,Z) :- Z =:= X + Y + 0.25.
+rel(X,Y) :- Y =:= X + 0.25.
+rel(X) :- X =:= 100_000.
+
+rel0(X) :- X =:= 100_000 0.
+rel0(X, 100_000_11, Y) :- X =:= Y.
diff --git a/Units/parser-prolog.r/simple.d/args.ctags b/Units/parser-prolog.r/simple.d/args.ctags
new file mode 100644
index 0000000000..71bea42029
--- /dev/null
+++ b/Units/parser-prolog.r/simple.d/args.ctags
@@ -0,0 +1,4 @@
+-G
+--sort=no
+--fields=+nEK
+--param-Prolog.allowNestedComments=1
diff --git a/Units/parser-prolog.r/simple.d/expected.tags b/Units/parser-prolog.r/simple.d/expected.tags
new file mode 100644
index 0000000000..c7ea8bbff1
--- /dev/null
+++ b/Units/parser-prolog.r/simple.d/expected.tags
@@ -0,0 +1,28 @@
+mother_child	input.pl	/^mother_child(trude, sally).$/;"	predicate	line:2	arity:2
+mother_child/2	input.pl	/^mother_child(trude, sally).$/;"	predicate	line:2	extras:arityAppended	arity:2
+father_child	input.pl	/^father_child(tom, sally).$/;"	predicate	line:4	arity:2
+father_child/2	input.pl	/^father_child(tom, sally).$/;"	predicate	line:4	extras:arityAppended	arity:2
+father_child	input.pl	/^father_child(tom, erica).$/;"	predicate	line:5	arity:2
+father_child/2	input.pl	/^father_child(tom, erica).$/;"	predicate	line:5	extras:arityAppended	arity:2
+father_child	input.pl	/^father_child(mike, tom).$/;"	predicate	line:6	arity:2
+father_child/2	input.pl	/^father_child(mike, tom).$/;"	predicate	line:6	extras:arityAppended	arity:2
+sibling	input.pl	/^sibling(X, Y)      :- parent_child(Z, X), parent_child(Z, Y).$/;"	predicate	line:8	arity:2
+sibling/2	input.pl	/^sibling(X, Y)      :- parent_child(Z, X), parent_child(Z, Y).$/;"	predicate	line:8	extras:arityAppended	arity:2
+parent_child	input.pl	/^parent_child(X, Y) :- father_child(X, Y).$/;"	predicate	line:10	arity:2
+parent_child/2	input.pl	/^parent_child(X, Y) :- father_child(X, Y).$/;"	predicate	line:10	extras:arityAppended	arity:2
+parent_child	input.pl	/^parent_child(X, Y) :- mother_child(X, Y).$/;"	predicate	line:11	arity:2
+parent_child/2	input.pl	/^parent_child(X, Y) :- mother_child(X, Y).$/;"	predicate	line:11	extras:arityAppended	arity:2
+not_dummy	input.pl	/^not_dummy.$/;"	predicate	line:16	arity:0
+not_dummy/0	input.pl	/^not_dummy.$/;"	predicate	line:16	extras:arityAppended	arity:0
+'quoted predicate'	input.pl	/^'quoted predicate'($/;"	predicate	line:18	arity:1
+'quoted predicate'/1	input.pl	/^'quoted predicate'($/;"	predicate	line:18	extras:arityAppended	arity:1
+rel	input.pl	/^rel(X,Y,Z) :- Z =:= X + Y + 0.25.$/;"	predicate	line:23	arity:3
+rel/3	input.pl	/^rel(X,Y,Z) :- Z =:= X + Y + 0.25.$/;"	predicate	line:23	extras:arityAppended	arity:3
+rel	input.pl	/^rel(X,Y) :- Y =:= X + 0.25.$/;"	predicate	line:24	arity:2
+rel/2	input.pl	/^rel(X,Y) :- Y =:= X + 0.25.$/;"	predicate	line:24	extras:arityAppended	arity:2
+rel	input.pl	/^rel(X) :- X =:= 100_000.$/;"	predicate	line:25	arity:1
+rel/1	input.pl	/^rel(X) :- X =:= 100_000.$/;"	predicate	line:25	extras:arityAppended	arity:1
+rel0	input.pl	/^rel0(X) :- X =:= 100_000 0.$/;"	predicate	line:27	arity:1
+rel0/1	input.pl	/^rel0(X) :- X =:= 100_000 0.$/;"	predicate	line:27	extras:arityAppended	arity:1
+rel0	input.pl	/^rel0(X, 100_000_11, Y) :- X =:= Y.$/;"	predicate	line:28	arity:3
+rel0/3	input.pl	/^rel0(X, 100_000_11, Y) :- X =:= Y.$/;"	predicate	line:28	extras:arityAppended	arity:3
diff --git a/Units/parser-prolog.r/simple.d/input.pl b/Units/parser-prolog.r/simple.d/input.pl
new file mode 100644
index 0000000000..63d8053d1d
--- /dev/null
+++ b/Units/parser-prolog.r/simple.d/input.pl
@@ -0,0 +1,28 @@
+%% Taken from https://en.wikipedia.org/wiki/Prolog
+mother_child(trude, sally).
+
+father_child(tom, sally).
+father_child(tom, erica).
+father_child(mike, tom).
+
+sibling(X, Y)      :- parent_child(Z, X), parent_child(Z, Y).
+
+parent_child(X, Y) :- father_child(X, Y).
+parent_child(X, Y) :- mother_child(X, Y).
+
+% dummy0()
+/* dummy1() */
+/* /* dummy2() */ */
+not_dummy.
+
+'quoted predicate'(
+X
+) :-
+	father_child(tom, X).
+
+rel(X,Y,Z) :- Z =:= X + Y + 0.25.
+rel(X,Y) :- Y =:= X + 0.25.
+rel(X) :- X =:= 100_000.
+
+rel0(X) :- X =:= 100_000 0.
+rel0(X, 100_000_11, Y) :- X =:= Y.
diff --git a/docs/news/HEAD.rst b/docs/news/HEAD.rst
index 0faa201c21..859755b5a3 100644
--- a/docs/news/HEAD.rst
+++ b/docs/news/HEAD.rst
@@ -44,6 +44,7 @@ The following parsers have been added:
 
 * SINEX: to handle SINEX (Solution INdependent EXchange) files
 * Netfilter: to handle the output of "nft list ..." command
+* Prolog
 
 Changes about parser specific kinds, roles, fields, and extras
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/main/parsers_p.h b/main/parsers_p.h
index c4cc4429de..2c16addd53 100644
--- a/main/parsers_p.h
+++ b/main/parsers_p.h
@@ -149,6 +149,7 @@
 	PkgConfigParser, \
 	PodParser, \
 	PowerShellParser, \
+	PrologParser, \
 	ProtobufParser, \
 	PuppetManifestParser, \
 	PythonParser, \
diff --git a/main/selectors.c b/main/selectors.c
index 6960cd46ba..fe7f31040f 100644
--- a/main/selectors.c
+++ b/main/selectors.c
@@ -43,6 +43,8 @@ static const char *TR_FORTRAN  = "Fortran";
 static const char *TR_V = "V";
 static const char *TR_VERILOG = "Verilog";
 
+static const char *TR_PROLOG = "Prolog";
+
 #define startsWith(line,prefix)									\
 	(strncmp(line, prefix, strlen(prefix)) == 0? true: false)
 
@@ -422,6 +424,64 @@ selectVOrVerilogByKeywords (MIO *input,
 		return TR_UNKNOWN;
 }
 
+struct PerlOrPrologScore {
+	int perl;
+	int prolog;
+	unsigned int linum;
+};
+
+static const char *
+tastePerlOrPrologLines (const char *line, void *data)
+{
+	struct PerlOrPrologScore *score = (struct PerlOrPrologScore *)data;
+
+	score->linum++;
+
+	if (score->linum > 16)
+		return TR_BREAK;
+
+	if (line[0] == '#' && line[1] != '!')
+	{
+		/* This is not a shebang: the comment line of perl */
+		score->perl++;
+	}
+	else if (line[0] == '%')
+	{
+		score->prolog++;
+	}
+	else if (startsWith (line, "use "))
+	{
+		score->perl++;
+	}
+	else if (startsWith (line, ":-"))
+		score->prolog += 2;
+	else if (strstr (line, ":-"))
+		score->prolog++;
+	else if (strstr (line, "/*"))
+		score->prolog++;
+
+	return TR_UNKNOWN;
+}
+
+const char *
+selectPerlOrPrologByDistinctiveToken (struct _MIO *input, langType *candidates, unsigned int nCandidates)
+{
+	struct PerlOrPrologScore score = {
+		.perl = 0,
+		.prolog = 0,
+		.linum = 0,
+	};
+	selectByLines (input, tastePerlOrPrologLines, TR_UNKNOWN, &score);
+
+	int d = score.perl - score.prolog;
+	if (d > 0)
+		return TR_PERL5;
+	else if (d < 0)
+		return TR_PROLOG;
+	else
+		return TR_UNKNOWN;
+}
+
 #ifdef HAVE_LIBXML
 #include <libxml/parser.h>
 #include <libxml/xpath.h>
diff --git a/main/selectors.h b/main/selectors.h
index fe48c64773..7571b7d51a 100644
--- a/main/selectors.h
+++ b/main/selectors.h
@@ -39,4 +39,7 @@ selectByXpathFileSpec (struct _MIO *input, langType *candidates, unsigned int nC
 const char *
 selectFortranOrForthByForthMarker (struct _MIO *input, langType *candidates, unsigned int nCandidates);
 
+const char *
+selectPerlOrPrologByDistinctiveToken (struct _MIO *input, langType *candidates, unsigned int nCandidates);
+
 #endif
diff --git a/parsers/perl.c b/parsers/perl.c
index 49992599f0..b566464a9a 100644
--- a/parsers/perl.c
+++ b/parsers/perl.c
@@ -1019,8 +1019,10 @@ extern parserDefinition* PerlParser (void)
 		/* cperl is an Emacs' editing mode for Perl source code  */
 		"cperl",
 		NULL };
-	static selectLanguage selectors [] = { selectByPickingPerlVersion,
-					       NULL };
+	static selectLanguage selectors [] = {
+		selectPerlOrPrologByDistinctiveToken,
+		selectByPickingPerlVersion,
+		NULL };
 	parserDefinition* def = parserNew ("Perl");
 	def->kindTable      = PerlKinds;
 	def->kindCount  = ARRAY_SIZE (PerlKinds);
diff --git a/parsers/prolog.c b/parsers/prolog.c
new file mode 100644
index 0000000000..2257441ab4
--- /dev/null
+++ b/parsers/prolog.c
@@ -0,0 +1,730 @@
+/*
+*   Copyright (c) 2025, Masatake YAMATO
+*
+*   This source code is released for free distribution under the terms of the
+*   GNU General Public License version 2 or (at your option) any later version.
+*
+*   This module contains functions for generating tags for prolog source file.
+*
+*   References:
+*   - https://www.swi-prolog.org/pldoc/man?section=syntax
+*   - https://sicstus.sics.se/sicstus/docs/3.7.1/html/sicstus_45.html
+*   - https://www.az-prolog.com/manual/manuals/manual_program.html (in Japanese)
+*
+*/
+
+/*
+*   INCLUDE FILES
+*/
+#include "general.h"        /* must always come first */
+
+#include "entry.h"
+#include "field.h"
+#include "keyword.h"
+#include "param.h"
+#include "parse.h"
+#include "read.h"
+#include "routines.h"
+#include "selectors.h"
+#include "tokeninfo.h"
+#include "vstring.h"
+#include "xtag.h"
+
+#include <string.h>
+
+/*
+*   DATA DECLARATIONS
+*/
+
+typedef enum {
+	K_PREDICATE,
+	K_GRAMMAR,
+	K_MODULE,
+} prologKind;
+
+typedef enum {
+	F_ARITY,
+} prologField;
+
+typedef enum {
+	X_ARITY,
+} prologXtag;
+
+typedef enum {
+	R_MODULE_CHAINELT,
+} prologModuleRole;
+
+
+typedef enum {
+	/* 0..255 are the byte's value */
+	TOKEN_EOF = 256,
+	TOKEN_UNDEFINED,
+	TOKEN_KEYWORD,
+
+	TOKEN_STRATOM,
+	TOKEN_STRING,
+	TOKEN_APPLY,
+	TOKEN_RULEOP,
+	TOKEN_DCGOP,
+
+	TOKEN_CODE,
+	TOKEN_ATOM,
+	TOKEN_VAR,
+	TOKEN_NUM,
+
+} prologTokenType;
+
+typedef enum {
+	KEYWORD_MODULE,
+#if 0
+	KEYWORD_USE_MODULE,
+	KEYWORD_AUTOLOAD,
+	KEYWORD_LIBRARY,
+#endif
+} prologKeyword;
+
+/*
+*   FUNCTION PROTOTYPES
+*/
+
+static void readToken (tokenInfo *const token, void *data CTAGS_ATTR_UNUSED);
+
+/*
+*   DATA DEFINITIONS
+*/
+
+static roleDefinition PrologModuleRoles [] = {
+	/* Currently V parser wants this items. */
+	{ false, "chainElt", "(EXPERIMENTAL)used as an element in a module-qualified atom like module:predicate" },
+};
+
+static kindDefinition PrologKinds []  = {
+	{true,  'p', "predicate", "predicates", },
+	{true,  'g', "grammar",   "grammars",   },
+	{true,  'm', "module",    "modules",
+	 .referenceOnly = false, ATTACH_ROLES(PrologModuleRoles),
+	},
+};
+
+static fieldDefinition PrologFields[] = {
+	{ .name = "arity",
+	  .description = "the number of parameters",
+	  .enabled = true,
+	  .dataType = FIELDTYPE_INTEGER,
+	},
+};
+
+static xtagDefinition PrologXtags [] = {
+	{ .enabled     = true,
+	  .name        = "arityAppended",
+	  .description = "Include predicates with their arities",
+	},
+};
+
+static bool prologAllowNestedComments = true;
+static bool prologAllowNestedCommentsHandler (const langType language CTAGS_ATTR_UNUSED,
+											  const char *name, const char *arg)
+{
+	prologAllowNestedComments = paramParserBool (arg, prologAllowNestedComments, name, "parameter");
+	return true;
+}
+
+static paramDefinition PrologParams [] = {
+	{ .name = "allowNestedComments",
+	  .desc = "allow nested comments like \"/* /* */ */\" ([true] or false)",
+	  .handleParam = prologAllowNestedCommentsHandler,
+	  /* https://www.swi-prolog.org/pldoc/man?section=nestedcomments */
+	},
+};
+
+static struct tokenTypePair prologTypePairs [] = {
+	{ '(', ')' },
+	{ '[', ']' },
+	{ '{', '}' },
+};
+
+static const keywordTable PrologKeywords[] = {
+	{ "module", KEYWORD_MODULE },
+};
+
+static struct tokenInfoClass prologTokenInfoClass = {
+	.nPreAlloc = 4,
+	.typeForUndefined = TOKEN_UNDEFINED,
+	.keywordNone      = KEYWORD_NONE,
+	.typeForKeyword   = TOKEN_KEYWORD,
+	.typeForEOF       = TOKEN_EOF,
+	.extraSpace       = 0,
+	.pairs            = prologTypePairs,
+	.pairCount        = ARRAY_SIZE (prologTypePairs),
+	.read             = readToken,
+};
+
+static langType Lang_prolog;
+
+/*
+*   FUNCTION DEFINITIONS
+*/
+
+static tokenInfo *newPrologToken (void)
+{
+	return newToken (&prologTokenInfoClass);
+}
+
+static void skipNestedBlockComment (int c)
+{
+	int depth = 1;
+
+	while (c != EOF)
+	{
+		if (c == '/')
+		{
+			c = getcFromInputFile ();
+			if (c == '*')
+			{
+				++depth;
+				c = getcFromInputFile ();
+			}
+		}
+		else if (c == '*')
+		{
+			c = getcFromInputFile ();
+			if (c == '/')
+			{
+				if (--depth == 0)
+					return;
+				c = getcFromInputFile ();
+			}
+		}
+		else
+			c = getcFromInputFile ();
+	}
+}
+
+static void skipBlockComment (int c)
+{
+	while (c != EOF)
+	{
+		if (c == '*')
+		{
+			c = getcFromInputFile ();
+			if (c == '/')
+				return;
+		}
+		else
+			c = getcFromInputFile ();
+	}
+}
+
+static void readString (tokenInfo *const token, int c)
+{
+	int terminator = c;
+
+	tokenPutc (token, c);
+	c = getcFromInputFile ();
+
+	while (c != EOF)
+	{
+		tokenPutc (token, c);
+
+		if (c == '\\')
+		{
+			/* consume the next char */
+			c = getcFromInputFile ();
+			if (c != EOF)
+			{
+				tokenPutc (token, c);
+				c = getcFromInputFile ();
+			}
+			continue;
+		}
+
+		if (c == terminator)
+			return;
+
+		c = getcFromInputFile ();
+	}
+}
+
+static void readNumber (tokenInfo *const token, int c)
+{
+	bool dpoint_seen = false;
+
+	tokenPutc (token, c);
+	c = getcFromInputFile ();
+
+	while (c != EOF)
+	{
+		// SWI prolog accepts:
+		//
+		//   1_000_000
+		//   1 000 000
+		//   1_000_/*more*/000
+		//
+		// We handle _ here.
+		//
+		if (isdigit (c) || c == '_')
+		{
+			tokenPutc (token, c);
+			c = getcFromInputFile ();
+			continue;
+		}
+
+		if (c == '.')
+		{
+			if (dpoint_seen)
+			{
+				ungetcToInputFile ('.');
+				return;
+			}
+
+			dpoint_seen = true;
+			int c0 = getcFromInputFile ();
+			if (isdigit (c0))
+			{
+				tokenPutc (token, '.');
+				tokenPutc (token, c0);
+				c = getcFromInputFile ();
+				continue;
+			}
+
+			ungetcToInputFile (c0);
+			ungetcToInputFile ('.');
+			return;
+		}
+
+		ungetcToInputFile (c);
+		return;
+	}
+}
+
+static void readAtom (tokenInfo *const token, int c)
+{
+	tokenPutc (token, c);
+	c = getcFromInputFile ();
+
+	while (c != EOF)
+	{
+		if (isalnum (c) || c == '_')
+		{
+			tokenPutc (token, c);
+			c = getcFromInputFile ();
+			continue;
+		}
+
+		ungetcToInputFile (c);
+		return;
+	}
+}
+
+static void readToken (tokenInfo *const token, void *data CTAGS_ATTR_UNUSED)
+{
+	int c;
+
+	token->type = TOKEN_UNDEFINED;
+	token->keyword = KEYWORD_NONE;
+	vStringClear (token->string);
+
+ getNextChar:
+	do
+		c = getcFromInputFile ();
+	while (c == ' ' || c == '\t' || c == '\f' || c == '\r' || c == '\n');
+
+	token->lineNumber   = getInputLineNumber ();
+	token->filePosition = getInputFilePosition ();
+
+	switch (c)
+	{
+	case EOF:
+		token->type = TOKEN_EOF;
+		break;
+	case '%':
+		do
+			c = getcFromInputFile ();
+		while (c != EOF && c != '\n');
+		goto getNextChar;
+	case '/':
+	{
+		int c0 = getcFromInputFile ();
+		if (c0 == '*')
+		{
+			c0 = getcFromInputFile ();
+			if (prologAllowNestedComments)
+				skipNestedBlockComment (c0);
+			else
+				skipBlockComment (c0);
+			goto getNextChar;
+		}
+		ungetcToInputFile (c0);
+		tokenPutc (token, c);
+		token->type = c;
+		break;
+	}
+	case '\'':
+	{
+		readString (token, c);
+		token->type = TOKEN_STRATOM;
+		break;
+	}
+	case '"':
+	{
+		readString (token, c);
+		token->type = TOKEN_STRING;
+		break;
+	}
+
+	case '(':
+	case ')':
+	case '{':
+	case '}':
+	case '[':
+	case ']':
+	case ',':
+	case '.':
+		tokenPutc(token, c);
+		token->type = c;
+		break;
+	case '=':
+	{
+		tokenPutc(token, c);
+		int c0 = getcFromInputFile ();
+		if (c0 == '.')
+		{
+			int c1 = getcFromInputFile ();
+			if (c1 == '.')
+			{
+				tokenCatS (token, "..");
+				token->type = TOKEN_APPLY;
+				break;
+			}
+			ungetcToInputFile (c1);
+		}
+		ungetcToInputFile (c0);
+		token->type = c;
+		break;
+	}
+	case ':':
+	{
+		tokenPutc(token, c);
+		int c0 = getcFromInputFile ();
+		if (c0 == '-')
+		{
+			tokenPutc(token, c0);
+			token->type = TOKEN_RULEOP;
+			break;
+		}
+		ungetcToInputFile (c0);
+		token->type = c;
+		break;
+	}
+	case '-':
+	{
+		tokenPutc(token, c);
+
+		int c0 = getcFromInputFile ();
+		if (c0 == '-')
+		{
+			int c1 = getcFromInputFile ();
+			if (c1 == '>')
+			{
+				tokenCatS (token, "->");
+				token->type = TOKEN_DCGOP;
+				break;
+			}
+			ungetcToInputFile (c1);
+		}
+		ungetcToInputFile (c0);
+		token->type = c;
+		break;
+	}
+	default:
+		if (c == '0')
+		{
+			int c0 = getcFromInputFile ();
+			if (c0 == '\'')
+			{
+				tokenPutc(token, c);
+				c = getcFromInputFile ();
+				if (c != EOF)
+					tokenPutc(token, c);
+
+				token->type = TOKEN_CODE;
+				break;
+			}
+			ungetcToInputFile (c0);
+			readNumber (token, c);
+			token->type = TOKEN_NUM;
+			return;
+		}
+		if (isdigit(c))
+		{
+			readNumber (token, c);
+			token->type = TOKEN_NUM;
+		}
+		else if (c == '_' || ('A' <= c && c <= 'Z'))
+		{
+			readAtom (token, c);
+			token->type = TOKEN_VAR;
+		}
+		else if ('a' <= c && c <= 'z')
+		{
+			readAtom (token, c);
+			token->keyword = lookupKeyword (tokenString (token), Lang_prolog);
+			token->type = (token->keyword == KEYWORD_NONE)
+				? TOKEN_ATOM
+				: TOKEN_KEYWORD;
+		}
+		else if (c == '-')
+		{
+			tokenPutc (token, c);
+			c = getcFromInputFile ();
+			if (isdigit (c))
+			{
+				readNumber (token, c);
+				token->type = TOKEN_NUM;
+			}
+			else
+			{
+				/* I wonder what I should do here? */
+				ungetcToInputFile (c);
+				token->type = TOKEN_ATOM;
+			}
+		}
+		else
+		{
+			tokenPutc (token, c);
+			if (c == '\\')
+			{
+				int c0 = getcFromInputFile ();
+				if (c0 != EOF)
+					tokenPutc (token, c0);
+			}
+			token->type = c;
+#if 0
+			tokenCatS (token, " REST :: ");
+			tokenCatS (token, getInputFileName ());
+#endif
+		}
+		break;
+	}
+}
+
+static void makePrologTagEntry (tokenInfo *const atom, prologKind kindex, int arity,
+								unsigned long endLine, int module)
+{
+	tagEntryInfo e, ex;
+	char arity_str[16];
+
+	tokenInitTagEntry (atom, &e, kindex);
+	setTagEndLine (&e, endLine);
+	e.extensionFields.scopeIndex = module;
+	snprintf (arity_str, sizeof (arity_str), "%d", arity);
+	attachParserField (&e, PrologFields[F_ARITY].ftype, arity_str);
+	makeTagEntry (&e);
+
+	tokenPutc (atom, '/');
+	tokenCatS (atom, arity_str);
+	tokenInitTagEntry (atom, &ex, kindex);
+	setTagEndLine (&ex, endLine);
+	ex.extensionFields.scopeIndex = module;
+	attachParserField (&ex, PrologFields[F_ARITY].ftype, arity_str);
+	markTagExtraBit (&ex, PrologXtags[X_ARITY].xtype);
+	makeTagEntry (&ex);
+}
+
+static int parseArguments (tokenInfo *const t)
+{
+	tokenRead (t);
+
+	int arity = 0;
+	while (!tokenIsEOF (t) && tokenSkipToOneOfTypes (t, true, ',', '(', ')'))
+	{
+		if (t->type == '(')
+			tokenSkipOverPair (t);
+		else
+		{
+			arity++;
+			if (t->type == ')')
+				break;
+		}
+		tokenRead (t);
+	}
+	return arity;
+}
+
+static void deleteBackToken (tokenInfo *t)
+{
+	if (!tokenIsEOF (t))
+		tokenUnread (t);
+	tokenDelete (t);
+}
+
+static int lookModuleAhead (void)
+{
+	int r = CORK_NIL;
+	tokenInfo *openparen = newPrologToken ();
+
+	tokenRead (openparen);
+	if (openparen->type == '(')
+	{
+		tokenInfo *mod = newPrologToken ();
+		tokenRead (mod);
+		if (tokenIsType (mod, ATOM))
+			r = tokenMakeSimpleTag (mod, K_MODULE);
+		deleteBackToken (mod);
+	}
+	deleteBackToken (openparen);
+
+	return r;
+}
+
+static int lookBodyAhead (void)
+{
+	int r = CORK_NIL;
+
+	tokenInfo *modpred = newPrologToken ();
+
+	tokenRead (modpred);
+	if (tokenIsKeyword (modpred, MODULE))
+		r = lookModuleAhead ();
+	deleteBackToken (modpred);
+
+	return r;
+}
+
+static int parseClause (tokenInfo *const t, int module)
+{
+	tokenInfo *atom = NULL;
+	int arity = 0;
+
+	if (tokenIsType (t, ATOM)
+		|| tokenIsType (t, STRATOM)
+		|| tokenIsType (t, KEYWORD))
+	{
+		atom = newPrologToken ();
+		tokenCopy (atom, t);
+
+		tokenRead (t);
+		if (tokenIsEOF (t))
+		{
+			tokenDelete (atom);
+			return module;
+		}
+		if (t->type == ':')
+		{
+			int chainelt = makeSimpleRefTag (atom->string, K_MODULE, R_MODULE_CHAINELT);
+			tokenDelete (atom);
+			tokenRead (t);
+			parseClause (t, chainelt);
+			return module;
+		}
+		else
+			tokenUnread (t);
+	}
+	else if (tokenIsType (t, RULEOP))
+	{
+		int newmod = lookBodyAhead ();
+		tokenSkipToOneOfTypes (t, true, '.');
+		if (newmod != CORK_NIL)
+			module = newmod;
+		return module;
+	}
+	else
+	{
+		tokenSkipToOneOfTypes (t, true, '.');
+		return module;
+	}
+
+	tokenRead (t);
+	if (atom)
+	{
+		int kindex = K_PREDICATE;
+
+		if (t->type == '(')
+		{
+			arity = parseArguments (t);
+			tokenRead (t);
+		}
+
+		if (tokenIsType (t, RULEOP)
+			|| tokenIsType (t, DCGOP))
+		{
+			if (tokenIsType (t, DCGOP))
+				kindex = K_GRAMMAR;
+			tokenSkipToOneOfTypes (t, true, '.');
+		}
+
+		if (t->type == '.')
+			makePrologTagEntry (atom, kindex, arity, t->lineNumber,
+								module);
+
+		tokenDelete (atom);
+	}
+
+	return module;
+}
+
+static void findPrologTags (void)
+{
+	int module = CORK_NIL;
+	tokenInfo *t = newPrologToken ();
+
+	while (1)
+	{
+		tokenRead (t);
+		if (tokenIsEOF (t))
+			break;
+		module = parseClause (t, module);
+	}
+
+	tokenDelete (t);
+}
+
+extern void initialize (const langType language)
+{
+	Lang_prolog = language;
+}
+
+extern parserDefinition* PrologParser (void)
+{
+	static const char *const extensions [] = {"pl", NULL};
+
+	/* Interpreters supporting shebang:
+	 *
+	 * + swipl
+	 *   https://www.swi-prolog.org/pldoc/man?section=plscript
+	 * + gprolog
+	 *   http://www.gprolog.org/manual/html_node/gprolog007.html
+	 * + yap
+	 *   https://github.com/search?q=repo%3Avscosta%2Fyap%20%20%22%23!%22&type=code
+	 */
+	static const char *const aliases [] = {
+		"swipl",
+		"gprolog",
+		"yap",
+		NULL
+	};
+
+	static selectLanguage selectors[] = { selectPerlOrPrologByDistinctiveToken, NULL };
+
+	parserDefinition* const def = parserNew ("Prolog");
+	def->initialize     = initialize;
+	def->parser         = findPrologTags;
+	def->extensions     = extensions;
+	def->aliases        = aliases;
+	def->selectLanguage = selectors;
+	def->keywordTable   = PrologKeywords;
+	def->keywordCount   = ARRAY_SIZE(PrologKeywords);
+	def->useCork        = CORK_QUEUE;
+	def->kindTable      = PrologKinds;
+	def->kindCount      = ARRAY_SIZE(PrologKinds);
+	def->fieldTable     = PrologFields;
+	def->fieldCount     = ARRAY_SIZE(PrologFields);
+	def->xtagTable      = PrologXtags;
+	def->xtagCount      = ARRAY_SIZE(PrologXtags);
+	def->paramTable     = PrologParams;
+	def->paramCount     = ARRAY_SIZE(PrologParams);
+	def->requestAutomaticFQTag = true;
+	def->defaultScopeSeparator = ":";
+
+	return def;
+}
diff --git a/source.mak b/source.mak
index 521a2a37a7..3568f19341 100644
--- a/source.mak
+++ b/source.mak
@@ -399,6 +399,7 @@ PARSER_SRCS =				\
 	parsers/perl-moose.c		\
 	parsers/php.c			\
 	parsers/powershell.c		\
+	parsers/prolog.c		\
 	parsers/protobuf.c		\
 	parsers/python.c		\
 	parsers/python-entry-points.c	\
diff --git a/win32/ctags_vs2013.vcxproj b/win32/ctags_vs2013.vcxproj
index 088e606811..0082c1c2ed 100644
--- a/win32/ctags_vs2013.vcxproj
+++ b/win32/ctags_vs2013.vcxproj
@@ -347,6 +347,7 @@
     <ClCompile Include="..\parsers\perl.c" />
     <ClCompile Include="..\parsers\php.c" />
     <ClCompile Include="..\parsers\powershell.c" />
+    <ClCompile Include="..\parsers\prolog.c" />
     <ClCompile Include="..\parsers\protobuf.c" />
     <ClCompile Include="..\parsers\python-entry-points.c" />
     <ClCompile Include="..\parsers\python-logging-config.c" />
diff --git a/win32/ctags_vs2013.vcxproj.filters b/win32/ctags_vs2013.vcxproj.filters
index ae70a81c10..2205e2d0bb 100644
--- a/win32/ctags_vs2013.vcxproj.filters
+++ b/win32/ctags_vs2013.vcxproj.filters
@@ -564,6 +564,9 @@
     <ClCompile Include="..\parsers\powershell.c">
       <Filter>Source Files\parsers</Filter>
     </ClCompile>
+    <ClCompile Include="..\parsers\prolog.c">
+      <Filter>Source Files\parsers</Filter>
+    </ClCompile>
     <ClCompile Include="..\parsers\protobuf.c">
       <Filter>Source Files\parsers</Filter>
     </ClCompile>

From c99c2f4acfb40fbeb8d92da15eab6cf2953e6744 Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Sun, 18 May 2025 17:44:54 +0900
Subject: [PATCH 6/6] validate-input: add swipl input validator

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---
 Units/parser-prolog.r/module.d/validator      |  1 +
 .../simple-flat-comment.d/validator           |  2 ++
 Units/parser-prolog.r/validator               |  1 +
 circle.yml                                    |  2 +-
 misc/validators/validator-swipl               | 34 +++++++++++++++++++
 5 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 Units/parser-prolog.r/module.d/validator
 create mode 100644 Units/parser-prolog.r/simple-flat-comment.d/validator
 create mode 100644 Units/parser-prolog.r/validator
 create mode 100755 misc/validators/validator-swipl

diff --git a/Units/parser-prolog.r/module.d/validator b/Units/parser-prolog.r/module.d/validator
new file mode 100644
index 0000000000..3b656016ee
--- /dev/null
+++ b/Units/parser-prolog.r/module.d/validator
@@ -0,0 +1 @@
+KNOWN-INVALIDATION
diff --git a/Units/parser-prolog.r/simple-flat-comment.d/validator b/Units/parser-prolog.r/simple-flat-comment.d/validator
new file mode 100644
index 0000000000..67ee2f64c9
--- /dev/null
+++ b/Units/parser-prolog.r/simple-flat-comment.d/validator
@@ -0,0 +1,2 @@
+KNOWN-INVALIDATION
+
diff --git a/Units/parser-prolog.r/validator b/Units/parser-prolog.r/validator
new file mode 100644
index 0000000000..8910b3134f
--- /dev/null
+++ b/Units/parser-prolog.r/validator
@@ -0,0 +1 @@
+swipl
diff --git a/circle.yml b/circle.yml
index 78911df7f1..d73eee3ed8 100644
--- a/circle.yml
+++ b/circle.yml
@@ -24,7 +24,7 @@ jobs:
              dnf -y install awk gcc automake autoconf pkgconfig make libseccomp-devel libxml2-devel jansson-devel libyaml-devel pcre2-devel findutils diffutils sudo
              dnf -y install jq puppet python3-sphinx
              # These are for input-validation.
-             dnf -y install g++ jq puppet nodejs gcc-gfortran gcc-gnat typescript
+             dnf -y install g++ jq puppet nodejs gcc-gfortran gcc-gnat typescript swi-prolog
              # nodejs requires libsqlite.so.0 with sqlite-session feature
              # It was turned off in 3.46.1-1.
              dnf -y update sqlite-libs
diff --git a/misc/validators/validator-swipl b/misc/validators/validator-swipl
new file mode 100755
index 0000000000..998aeb927c
--- /dev/null
+++ b/misc/validators/validator-swipl
@@ -0,0 +1,34 @@
+# -*- sh -*-
+# validator-swipl - validating Prolog input files with swipl
+#
+#  Copyright (c) 2025 Masatake YAMATO
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+# USA.
+#
+action=$1
+input="$2"
+cmd=swipl
+flags="--on-error=status -g halt."
+case "$action" in
+    is_runnable)
+	type $cmd > /dev/null 2>&1
+	exit $?
+	;;
+    validate)
+	$cmd $flags "$input" > /dev/null
+	exit $?
+	;;
+esac