Create doxygen documentation for ELPA

The user functions of ELPA are now documented with doxygen tags.
At the moment the interface of ELPA 2015.11.001 is decribed.

The documentation has step by step to be implemented for all functions
and test programms.

Makefile.am

@@ -292,6 +292,8 @@ elpa2.i: $(top_srcdir)/src/elpa2.F90
 elpa1.i: $(top_srcdir)/src/elpa1.F90
 	$(CPP) $(CPPFLAGS) -I$(top_builddir)/ -c $(top_srcdir)/src/elpa1.F90 -o $@
 
+include doxygen.am
+
 CLEANFILES = \
   elpa-generated.h \
   elpa1_test_real.sh \

configure.ac

@@ -660,6 +660,12 @@ fi
 
 LT_INIT
 
+DX_PDF_FEATURE(OFF)
+DX_PS_FEATURE(OFF)
+DX_MAN_FEATURE(ON)
+DX_HTML_FEATURE(ON)
+DX_INIT_DOXYGEN([ELPA], [Doxyfile], [docs])
+
 AC_SUBST([WITH_MKL])
 AC_SUBST([WITH_BLACS])
 AC_SUBST([with_amd_bulldozer_kernel])
@@ -669,6 +675,7 @@ AC_SUBST([OPENMP_CFLAGS])
 AC_SUBST([OPENMP_FCFLAGS])
 AC_SUBST([OPENMP_LDFLAGS])
 #AC_SUBST(OPT_FCFLAGS)
+AC_SUBST([DOXYGEN_OUTPUT_DIR], [docs])
 
 rm -rf modules/ .fortran_dependencies/
 mkdir modules
@@ -702,6 +709,7 @@ AC_SUBST([PKG_CONFIG_FILE],[elpa${SUFFIX}-${PACKAGE_VERSION}.pc])
 
 AC_CONFIG_FILES([
   Makefile
+  Doxyfile
   ${PKG_CONFIG_FILE}:elpa.pc.in
 ])
 

doxygen.am

+## --------------------------------- ##
+## Format-independent Doxygen rules. ##
+## --------------------------------- ##
+
+if DX_COND_doc
+
+## ------------------------------- ##
+## Rules specific for HTML output. ##
+## ------------------------------- ##
+
+if DX_COND_html
+
+DX_CLEAN_HTML = @DX_DOCDIR@/html
+
+endif DX_COND_html
+
+## ------------------------------ ##
+## Rules specific for CHM output. ##
+## ------------------------------ ##
+
+if DX_COND_chm
+
+DX_CLEAN_CHM = @DX_DOCDIR@/chm
+
+if DX_COND_chi
+
+DX_CLEAN_CHI = @DX_DOCDIR@/@PACKAGE@.chi
+
+endif DX_COND_chi
+
+endif DX_COND_chm
+
+## ------------------------------ ##
+## Rules specific for MAN output. ##
+## ------------------------------ ##
+
+if DX_COND_man
+
+DX_CLEAN_MAN = @DX_DOCDIR@/man
+
+endif DX_COND_man
+
+## ------------------------------ ##
+## Rules specific for RTF output. ##
+## ------------------------------ ##
+
+if DX_COND_rtf
+
+DX_CLEAN_RTF = @DX_DOCDIR@/rtf
+
+endif DX_COND_rtf
+
+## ------------------------------ ##
+## Rules specific for XML output. ##
+## ------------------------------ ##
+
+if DX_COND_xml
+
+DX_CLEAN_XML = @DX_DOCDIR@/xml
+
+endif DX_COND_xml
+
+## ----------------------------- ##
+## Rules specific for PS output. ##
+## ----------------------------- ##
+
+if DX_COND_ps
+
+DX_CLEAN_PS = @DX_DOCDIR@/@PACKAGE@.ps
+
+DX_PS_GOAL = doxygen-ps
+
+doxygen-ps: @DX_DOCDIR@/@PACKAGE@.ps
+
+@DX_DOCDIR@/@PACKAGE@.ps: @DX_DOCDIR@/@PACKAGE@.tag
+	cd @DX_DOCDIR@/latex; \
+	rm -f *.aux *.toc *.idx *.ind *.ilg *.log *.out; \
+	$(DX_LATEX) refman.tex; \
+	$(MAKEINDEX_PATH) refman.idx; \
+	$(DX_LATEX) refman.tex; \
+	countdown=5; \
+	while $(DX_EGREP) 'Rerun (LaTeX|to get cross-references right)' \
+	                  refman.log > /dev/null 2>&1 \
+	   && test $$countdown -gt 0; do \
+	    $(DX_LATEX) refman.tex; \
+	    countdown=`expr $$countdown - 1`; \
+	done; \
+	$(DX_DVIPS) -o ../@PACKAGE@.ps refman.dvi
+
+endif DX_COND_ps
+
+## ------------------------------ ##
+## Rules specific for PDF output. ##
+## ------------------------------ ##
+
+if DX_COND_pdf
+
+DX_CLEAN_PDF = @DX_DOCDIR@/@PACKAGE@.pdf
+
+DX_PDF_GOAL = doxygen-pdf
+
+doxygen-pdf: @DX_DOCDIR@/@PACKAGE@.pdf
+
+@DX_DOCDIR@/@PACKAGE@.pdf: @DX_DOCDIR@/@PACKAGE@.tag
+	cd @DX_DOCDIR@/latex; \
+	rm -f *.aux *.toc *.idx *.ind *.ilg *.log *.out; \
+	$(DX_PDFLATEX) refman.tex; \
+	$(DX_MAKEINDEX) refman.idx; \
+	$(DX_PDFLATEX) refman.tex; \
+	countdown=5; \
+	while $(DX_EGREP) 'Rerun (LaTeX|to get cross-references right)' \
+	                  refman.log > /dev/null 2>&1 \
+	   && test $$countdown -gt 0; do \
+	    $(DX_PDFLATEX) refman.tex; \
+	    countdown=`expr $$countdown - 1`; \
+	done; \
+	mv refman.pdf ../@PACKAGE@.pdf
+
+endif DX_COND_pdf
+
+## ------------------------------------------------- ##
+## Rules specific for LaTeX (shared for PS and PDF). ##
+## ------------------------------------------------- ##
+
+if DX_COND_latex
+
+DX_CLEAN_LATEX = @DX_DOCDIR@/latex
+
+endif DX_COND_latex
+
+.PHONY: doxygen-run doxygen-doc $(DX_PS_GOAL) $(DX_PDF_GOAL)
+
+.INTERMEDIATE: doxygen-run $(DX_PS_GOAL) $(DX_PDF_GOAL)
+
+doxygen-run: @DX_DOCDIR@/@PACKAGE@.tag
+
+doxygen-doc: doxygen-run $(DX_PS_GOAL) $(DX_PDF_GOAL)
+
+@DX_DOCDIR@/@PACKAGE@.tag: $(DX_CONFIG) $(pkginclude_HEADERS)
+	rm -rf @DX_DOCDIR@
+	$(DX_ENV) $(DX_DOXYGEN) $(DX_CONFIG)
+
+DX_CLEANFILES = \
+	@DX_DOCDIR@/@PACKAGE@.tag \
+	-r \
+	$(DX_CLEAN_HTML) \
+	$(DX_CLEAN_CHM) \
+	$(DX_CLEAN_CHI) \
+	$(DX_CLEAN_MAN) \
+	$(DX_CLEAN_RTF) \
+	$(DX_CLEAN_XML) \
+	$(DX_CLEAN_PS) \
+	$(DX_CLEAN_PDF) \
+	$(DX_CLEAN_LATEX)
+
+endif DX_COND_doc

m4/ax_prog_doxygen.m4

+# ===========================================================================
+#      http://www.gnu.org/software/autoconf-archive/ax_prog_doxygen.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   DX_INIT_DOXYGEN(PROJECT-NAME, DOXYFILE-PATH, [OUTPUT-DIR])
+#   DX_DOXYGEN_FEATURE(ON|OFF)
+#   DX_DOT_FEATURE(ON|OFF)
+#   DX_HTML_FEATURE(ON|OFF)
+#   DX_CHM_FEATURE(ON|OFF)
+#   DX_CHI_FEATURE(ON|OFF)
+#   DX_MAN_FEATURE(ON|OFF)
+#   DX_RTF_FEATURE(ON|OFF)
+#   DX_XML_FEATURE(ON|OFF)
+#   DX_PDF_FEATURE(ON|OFF)
+#   DX_PS_FEATURE(ON|OFF)
+#
+# DESCRIPTION
+#
+#   The DX_*_FEATURE macros control the default setting for the given
+#   Doxygen feature. Supported features are 'DOXYGEN' itself, 'DOT' for
+#   generating graphics, 'HTML' for plain HTML, 'CHM' for compressed HTML
+#   help (for MS users), 'CHI' for generating a seperate .chi file by the
+#   .chm file, and 'MAN', 'RTF', 'XML', 'PDF' and 'PS' for the appropriate
+#   output formats. The environment variable DOXYGEN_PAPER_SIZE may be
+#   specified to override the default 'a4wide' paper size.
+#
+#   By default, HTML, PDF and PS documentation is generated as this seems to
+#   be the most popular and portable combination. MAN pages created by
+#   Doxygen are usually problematic, though by picking an appropriate subset
+#   and doing some massaging they might be better than nothing. CHM and RTF
+#   are specific for MS (note that you can't generate both HTML and CHM at
+#   the same time). The XML is rather useless unless you apply specialized
+#   post-processing to it.
+#
+#   The macros mainly control the default state of the feature. The use can
+#   override the default by specifying --enable or --disable. The macros
+#   ensure that contradictory flags are not given (e.g.,
+#   --enable-doxygen-html and --enable-doxygen-chm,
+#   --enable-doxygen-anything with --disable-doxygen, etc.) Finally, each
+#   feature will be automatically disabled (with a warning) if the required
+#   programs are missing.
+#
+#   Once all the feature defaults have been specified, call DX_INIT_DOXYGEN
+#   with the following parameters: a one-word name for the project for use
+#   as a filename base etc., an optional configuration file name (the
+#   default is 'Doxyfile', the same as Doxygen's default), and an optional
+#   output directory name (the default is 'doxygen-doc').
+#
+#   Automake Support
+#
+#   The following is a template aminclude.am file for use with Automake.
+#   Make targets and variables values are controlled by the various
+#   DX_COND_* conditionals set by autoconf.
+#
+#   The provided targets are:
+#
+#     doxygen-doc: Generate all doxygen documentation.
+#
+#     doxygen-run: Run doxygen, which will generate some of the
+#                  documentation (HTML, CHM, CHI, MAN, RTF, XML)
+#                  but will not do the post processing required
+#                  for the rest of it (PS, PDF, and some MAN).
+#
+#     doxygen-man: Rename some doxygen generated man pages.
+#
+#     doxygen-ps:  Generate doxygen PostScript documentation.
+#
+#     doxygen-pdf: Generate doxygen PDF documentation.
+#
+#   Note that by default these are not integrated into the automake targets.
+#   If doxygen is used to generate man pages, you can achieve this
+#   integration by setting man3_MANS to the list of man pages generated and
+#   then adding the dependency:
+#
+#     $(man3_MANS): doxygen-doc
+#
+#   This will cause make to run doxygen and generate all the documentation.
+#
+#   The following variable is intended for use in Makefile.am:
+#
+#     DX_CLEANFILES = everything to clean.
+#
+#   Then add this variable to MOSTLYCLEANFILES.
+#
+#     ----- begin aminclude.am -------------------------------------
+#
+#     ## --------------------------------- ##
+#     ## Format-independent Doxygen rules. ##
+#     ## --------------------------------- ##
+#
+#     if DX_COND_doc
+#
+#     ## ------------------------------- ##
+#     ## Rules specific for HTML output. ##
+#     ## ------------------------------- ##
+#
+#     if DX_COND_html
+#
+#     DX_CLEAN_HTML = @DX_DOCDIR@/html
+#
+#     endif DX_COND_html
+#
+#     ## ------------------------------ ##
+#     ## Rules specific for CHM output. ##
+#     ## ------------------------------ ##
+#
+#     if DX_COND_chm
+#
+#     DX_CLEAN_CHM = @DX_DOCDIR@/chm
+#
+#     if DX_COND_chi
+#
+#     DX_CLEAN_CHI = @DX_DOCDIR@/@PACKAGE@.chi
+#
+#     endif DX_COND_chi
+#
+#     endif DX_COND_chm
+#
+#     ## ------------------------------ ##
+#     ## Rules specific for MAN output. ##
+#     ## ------------------------------ ##
+#
+#     if DX_COND_man
+#
+#     DX_CLEAN_MAN = @DX_DOCDIR@/man
+#
+#     endif DX_COND_man
+#
+#     ## ------------------------------ ##
+#     ## Rules specific for RTF output. ##
+#     ## ------------------------------ ##
+#
+#     if DX_COND_rtf
+#
+#     DX_CLEAN_RTF = @DX_DOCDIR@/rtf
+#
+#     endif DX_COND_rtf
+#
+#     ## ------------------------------ ##
+#     ## Rules specific for XML output. ##
+#     ## ------------------------------ ##
+#
+#     if DX_COND_xml
+#
+#     DX_CLEAN_XML = @DX_DOCDIR@/xml
+#
+#     endif DX_COND_xml
+#
+#     ## ----------------------------- ##
+#     ## Rules specific for PS output. ##
+#     ## ----------------------------- ##
+#
+#     if DX_COND_ps
+#
+#     DX_CLEAN_PS = @DX_DOCDIR@/@PACKAGE@.ps
+#
+#     DX_PS_GOAL = doxygen-ps
+#
+#     doxygen-ps: @DX_DOCDIR@/@PACKAGE@.ps
+#
+#     @DX_DOCDIR@/@PACKAGE@.ps: @DX_DOCDIR@/@PACKAGE@.tag
+#         cd @DX_DOCDIR@/latex; \
+#         rm -f *.aux *.toc *.idx *.ind *.ilg *.log *.out; \
+#         $(DX_LATEX) refman.tex; \
+#         $(MAKEINDEX_PATH) refman.idx; \
+#         $(DX_LATEX) refman.tex; \
+#         countdown=5; \
+#         while $(DX_EGREP) 'Rerun (LaTeX|to get cross-references right)' \
+#                           refman.log > /dev/null 2>&1 \
+#            && test $$countdown -gt 0; do \
+#             $(DX_LATEX) refman.tex; \
+#             countdown=`expr $$countdown - 1`; \
+#         done; \
+#         $(DX_DVIPS) -o ../@PACKAGE@.ps refman.dvi
+#
+#     endif DX_COND_ps
+#
+#     ## ------------------------------ ##
+#     ## Rules specific for PDF output. ##
+#     ## ------------------------------ ##
+#
+#     if DX_COND_pdf
+#
+#     DX_CLEAN_PDF = @DX_DOCDIR@/@PACKAGE@.pdf
+#
+#     DX_PDF_GOAL = doxygen-pdf
+#
+#     doxygen-pdf: @DX_DOCDIR@/@PACKAGE@.pdf
+#
+#     @DX_DOCDIR@/@PACKAGE@.pdf: @DX_DOCDIR@/@PACKAGE@.tag
+#         cd @DX_DOCDIR@/latex; \
+#         rm -f *.aux *.toc *.idx *.ind *.ilg *.log *.out; \
+#         $(DX_PDFLATEX) refman.tex; \
+#         $(DX_MAKEINDEX) refman.idx; \
+#         $(DX_PDFLATEX) refman.tex; \
+#         countdown=5; \
+#         while $(DX_EGREP) 'Rerun (LaTeX|to get cross-references right)' \
+#                           refman.log > /dev/null 2>&1 \
+#            && test $$countdown -gt 0; do \
+#             $(DX_PDFLATEX) refman.tex; \
+#             countdown=`expr $$countdown - 1`; \
+#         done; \
+#         mv refman.pdf ../@PACKAGE@.pdf
+#
+#     endif DX_COND_pdf
+#
+#     ## ------------------------------------------------- ##
+#     ## Rules specific for LaTeX (shared for PS and PDF). ##
+#     ## ------------------------------------------------- ##
+#
+#     if DX_COND_latex
+#
+#     DX_CLEAN_LATEX = @DX_DOCDIR@/latex
+#
+#     endif DX_COND_latex
+#
+#     .PHONY: doxygen-run doxygen-doc $(DX_PS_GOAL) $(DX_PDF_GOAL)
+#
+#     .INTERMEDIATE: doxygen-run $(DX_PS_GOAL) $(DX_PDF_GOAL)
+#
+#     doxygen-run: @DX_DOCDIR@/@PACKAGE@.tag
+#
+#     doxygen-doc: doxygen-run $(DX_PS_GOAL) $(DX_PDF_GOAL)
+#
+#     @DX_DOCDIR@/@PACKAGE@.tag: $(DX_CONFIG) $(pkginclude_HEADERS)
+#         rm -rf @DX_DOCDIR@
+#         $(DX_ENV) $(DX_DOXYGEN) $(srcdir)/$(DX_CONFIG)
+#
+#     DX_CLEANFILES = \
+#         @DX_DOCDIR@/@PACKAGE@.tag \
+#         -r \
+#         $(DX_CLEAN_HTML) \
+#         $(DX_CLEAN_CHM) \
+#         $(DX_CLEAN_CHI) \
+#         $(DX_CLEAN_MAN) \
+#         $(DX_CLEAN_RTF) \
+#         $(DX_CLEAN_XML) \
+#         $(DX_CLEAN_PS) \
+#         $(DX_CLEAN_PDF) \
+#         $(DX_CLEAN_LATEX)
+#
+#     endif DX_COND_doc
+#
+#     ----- end aminclude.am ---------------------------------------
+#
+# LICENSE
+#
+#   Copyright (c) 2009 Oren Ben-Kiki <oren@ben-kiki.org>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 12
+
+## ----------##
+## Defaults. ##
+## ----------##
+
+DX_ENV=""
+AC_DEFUN([DX_FEATURE_doc],  ON)
+AC_DEFUN([DX_FEATURE_dot],  OFF)
+AC_DEFUN([DX_FEATURE_man],  OFF)
+AC_DEFUN([DX_FEATURE_html], ON)
+AC_DEFUN([DX_FEATURE_chm],  OFF)
+AC_DEFUN([DX_FEATURE_chi],  OFF)
+AC_DEFUN([DX_FEATURE_rtf],  OFF)
+AC_DEFUN([DX_FEATURE_xml],  OFF)
+AC_DEFUN([DX_FEATURE_pdf],  ON)
+AC_DEFUN([DX_FEATURE_ps],   ON)
+
+## --------------- ##
+## Private macros. ##
+## --------------- ##
+
+# DX_ENV_APPEND(VARIABLE, VALUE)
+# ------------------------------
+# Append VARIABLE="VALUE" to DX_ENV for invoking doxygen.
+AC_DEFUN([DX_ENV_APPEND], [AC_SUBST([DX_ENV], ["$DX_ENV $1='$2'"])])
+
+# DX_DIRNAME_EXPR
+# ---------------
+# Expand into a shell expression prints the directory part of a path.
+AC_DEFUN([DX_DIRNAME_EXPR],
+         [[expr ".$1" : '\(\.\)[^/]*$' \| "x$1" : 'x\(.*\)/[^/]*$']])
+
+# DX_IF_FEATURE(FEATURE, IF-ON, IF-OFF)
+# -------------------------------------
+# Expands according to the M4 (static) status of the feature.
+AC_DEFUN([DX_IF_FEATURE], [ifelse(DX_FEATURE_$1, ON, [$2], [$3])])
+
+# DX_REQUIRE_PROG(VARIABLE, PROGRAM)
+# ----------------------------------
+# Require the specified program to be found for the DX_CURRENT_FEATURE to work.
+AC_DEFUN([DX_REQUIRE_PROG], [
+AC_PATH_TOOL([$1], [$2])
+if test "$DX_FLAG_[]DX_CURRENT_FEATURE$$1" = 1; then
+    AC_MSG_WARN([$2 not found - will not DX_CURRENT_DESCRIPTION])
+    AC_SUBST(DX_FLAG_[]DX_CURRENT_FEATURE, 0)
+fi
+])
+
+# DX_TEST_FEATURE(FEATURE)
+# ------------------------
+# Expand to a shell expression testing whether the feature is active.
+AC_DEFUN([DX_TEST_FEATURE], [test "$DX_FLAG_$1" = 1])
+
+# DX_CHECK_DEPEND(REQUIRED_FEATURE, REQUIRED_STATE)
+# -------------------------------------------------
+# Verify that a required features has the right state before trying to turn on
+# the DX_CURRENT_FEATURE.
+AC_DEFUN([DX_CHECK_DEPEND], [
+test "$DX_FLAG_$1" = "$2" \
+|| AC_MSG_ERROR([doxygen-DX_CURRENT_FEATURE ifelse([$2], 1,
+                            requires, contradicts) doxygen-DX_CURRENT_FEATURE])
+])
+
+# DX_CLEAR_DEPEND(FEATURE, REQUIRED_FEATURE, REQUIRED_STATE)
+# ----------------------------------------------------------
+# Turn off the DX_CURRENT_FEATURE if the required feature is off.
+AC_DEFUN([DX_CLEAR_DEPEND], [
+test "$DX_FLAG_$1" = "$2" || AC_SUBST(DX_FLAG_[]DX_CURRENT_FEATURE, 0)
+])
+
+# DX_FEATURE_ARG(FEATURE, DESCRIPTION,
+#                CHECK_DEPEND, CLEAR_DEPEND,
+#                REQUIRE, DO-IF-ON, DO-IF-OFF)
+# --------------------------------------------
+# Parse the command-line option controlling a feature. CHECK_DEPEND is called
+# if the user explicitly turns the feature on (and invokes DX_CHECK_DEPEND),
+# otherwise CLEAR_DEPEND is called to turn off the default state if a required
+# feature is disabled (using DX_CLEAR_DEPEND). REQUIRE performs additional
+# requirement tests (DX_REQUIRE_PROG). Finally, an automake flag is set and
+# DO-IF-ON or DO-IF-OFF are called according to the final state of the feature.
+AC_DEFUN([DX_ARG_ABLE], [
+    AC_DEFUN([DX_CURRENT_FEATURE], [$1])
+    AC_DEFUN([DX_CURRENT_DESCRIPTION], [$2])
+    AC_ARG_ENABLE(doxygen-$1,
+                  [AS_HELP_STRING(DX_IF_FEATURE([$1], [--disable-doxygen-$1],
+                                                      [--enable-doxygen-$1]),
+                                  DX_IF_FEATURE([$1], [don't $2], [$2]))],
+                  [
+case "$enableval" in
+#(
+y|Y|yes|Yes|YES)
+    AC_SUBST([DX_FLAG_$1], 1)
+    $3
+;; #(
+n|N|no|No|NO)
+    AC_SUBST([DX_FLAG_$1], 0)
+;; #(
+*)
+    AC_MSG_ERROR([invalid value '$enableval' given to doxygen-$1])
+;;
+esac
+], [
+AC_SUBST([DX_FLAG_$1], [DX_IF_FEATURE([$1], 1, 0)])
+$4
+])
+if DX_TEST_FEATURE([$1]); then
+    $5
+    :
+fi
+AM_CONDITIONAL(DX_COND_$1, DX_TEST_FEATURE([$1]))
+if DX_TEST_FEATURE([$1]); then
+    $6
+    :
+else
+    $7
+    :
+fi
+])
+
+## -------------- ##
+## Public macros. ##
+## -------------- ##
+
+# DX_XXX_FEATURE(DEFAULT_STATE)
+# -----------------------------
+AC_DEFUN([DX_DOXYGEN_FEATURE], [AC_DEFUN([DX_FEATURE_doc],  [$1])])
+AC_DEFUN([DX_DOT_FEATURE],     [AC_DEFUN([DX_FEATURE_dot], [$1])])
+AC_DEFUN([DX_MAN_FEATURE],     [AC_DEFUN([DX_FEATURE_man],  [$1])])
+AC_DEFUN([DX_HTML_FEATURE],    [AC_DEFUN([DX_FEATURE_html], [$1])])
+AC_DEFUN([DX_CHM_FEATURE],     [AC_DEFUN([DX_FEATURE_chm],  [$1])])
+AC_DEFUN([DX_CHI_FEATURE],     [AC_DEFUN([DX_FEATURE_chi],  [$1])])
+AC_DEFUN([DX_RTF_FEATURE],     [AC_DEFUN([DX_FEATURE_rtf],  [$1])])
+AC_DEFUN([DX_XML_FEATURE],     [AC_DEFUN([DX_FEATURE_xml],  [$1])])
+AC_DEFUN([DX_XML_FEATURE],     [AC_DEFUN([DX_FEATURE_xml],  [$1])])
+AC_DEFUN([DX_PDF_FEATURE],     [AC_DEFUN([DX_FEATURE_pdf],  [$1])])
+AC_DEFUN([DX_PS_FEATURE],      [AC_DEFUN([DX_FEATURE_ps],   [$1])])
+
+# DX_INIT_DOXYGEN(PROJECT, [CONFIG-FILE], [OUTPUT-DOC-DIR])
+# ---------------------------------------------------------
+# PROJECT also serves as the base name for the documentation files.
+# The default CONFIG-FILE is "Doxyfile" and OUTPUT-DOC-DIR is "doxygen-doc".
+AC_DEFUN([DX_INIT_DOXYGEN], [
+
+# Files:
+AC_SUBST([DX_PROJECT], [$1])
+AC_SUBST([DX_CONFIG], [ifelse([$2], [], Doxyfile, [$2])])
+AC_SUBST([DX_DOCDIR], [ifelse([$3], [], doxygen-doc, [$3])])
+
+# Environment variables used inside doxygen.cfg:
+DX_ENV_APPEND(SRCDIR, $srcdir)
+DX_ENV_APPEND(PROJECT, $DX_PROJECT)
+DX_ENV_APPEND(DOCDIR, $DX_DOCDIR)
+DX_ENV_APPEND(VERSION, $PACKAGE_VERSION)
+
+# Doxygen itself:
+DX_ARG_ABLE(doc, [generate any doxygen documentation],
+            [],
+            [],
+            [DX_REQUIRE_PROG([DX_DOXYGEN], doxygen)
+             DX_REQUIRE_PROG([DX_PERL], perl)],
+            [DX_ENV_APPEND(PERL_PATH, $DX_PERL)])
+
+# Dot for graphics:
+DX_ARG_ABLE(dot, [generate graphics for doxygen documentation],
+            [DX_CHECK_DEPEND(doc, 1)],
+            [DX_CLEAR_DEPEND(doc, 1)],
+            [DX_REQUIRE_PROG([DX_DOT], dot)],
+            [DX_ENV_APPEND(HAVE_DOT, YES)
+             DX_ENV_APPEND(DOT_PATH, [`DX_DIRNAME_EXPR($DX_DOT)`])],
+            [DX_ENV_APPEND(HAVE_DOT, NO)])
+
+# Man pages generation:
+DX_ARG_ABLE(man, [generate doxygen manual pages],
+            [DX_CHECK_DEPEND(doc, 1)],
+            [DX_CLEAR_DEPEND(doc, 1)],
+            [],
+            [DX_ENV_APPEND(GENERATE_MAN, YES)],
+            [DX_ENV_APPEND(GENERATE_MAN, NO)])
+
+# RTF file generation:
+DX_ARG_ABLE(rtf, [generate doxygen RTF documentation],
+            [DX_CHECK_DEPEND(doc, 1)],
+            [DX_CLEAR_DEPEND(doc, 1)],
+            [],
+            [DX_ENV_APPEND(GENERATE_RTF, YES)],
+            [DX_ENV_APPEND(GENERATE_RTF, NO)])
+
+# XML file generation:
+DX_ARG_ABLE(xml, [generate doxygen XML documentation],
+            [DX_CHECK_DEPEND(doc, 1)],
+            [DX_CLEAR_DEPEND(doc, 1)],
+            [],
+            [DX_ENV_APPEND(GENERATE_XML, YES)],
+            [DX_ENV_APPEND(GENERATE_XML, NO)])
+
+# (Compressed) HTML help generation:
+DX_ARG_ABLE(chm, [generate doxygen compressed HTML help documentation],
+            [DX_CHECK_DEPEND(doc, 1)],
+            [DX_CLEAR_DEPEND(doc, 1)],
+            [DX_REQUIRE_PROG([DX_HHC], hhc)],
+            [DX_ENV_APPEND(HHC_PATH, $DX_HHC)
+             DX_ENV_APPEND(GENERATE_HTML, YES)
+             DX_ENV_APPEND(GENERATE_HTMLHELP, YES)],
+            [DX_ENV_APPEND(GENERATE_HTMLHELP, NO)])
+
+# Seperate CHI file generation.
+DX_ARG_ABLE(chi, [generate doxygen seperate compressed HTML help index file],
+            [DX_CHECK_DEPEND(chm, 1)],
+            [DX_CLEAR_DEPEND(chm, 1)],