Adding support for doxygen generation

m4/ac_prog_doxygen.m4

@@ -0,0 +1,54 @@
+dnl Check for doxygen to create API docs
+dnl
+AC_DEFUN([AC_PROG_DOXYGEN],
+[
+AC_ARG_ENABLE(doxygen,
+AS_HELP_STRING([--enable-doxygen],[enable documentation generation with doxygen (auto)]))
+
+AC_ARG_ENABLE(dot,
+AS_HELP_STRING([--enable-dot],[use 'dot' to generate graphs in doxygen (auto)]))              
+AC_ARG_ENABLE(html-docs,
+AS_HELP_STRING([--enable-html-docs],[enable HTML generation with doxygen (yes)]),
+[],[ enable_html_docs=yes])              
+AC_ARG_ENABLE(latex-docs,
+AS_HELP_STRING([--enable-latex-docs],
+[enable LaTeX documentation generation with doxygen (no)]),[],[enable_latex_docs=no])              
+
+if test "x$enable_doxygen" = xno; then
+ enable_doc=no	
+else 
+ AC_CHECK_PROG(DOXYGEN, doxygen, doxygen)
+ if test x$DOXYGEN = x; then
+  if test "x$enable_doxygen" = xyes; then
+   AC_MSG_ERROR([could not find doxygen])
+  fi
+  enable_doc=no
+ else
+  doxy_ver=`doxygen --version`
+  doxy_major=`expr "$doxy_ver" : '\(@<:@0-9@:>@\)\..*'`
+  doxy_minor=`expr "$doxy_ver" : '@<:@0-9@:>@\.\(@<:@0-9@:>@\).*'`
+  if test $doxy_major -eq "1" -a $doxy_minor -ge "3" ; then
+   enable_doc=yes
+   AC_CHECK_PROG(DOT, dot, dot)
+  else
+   AC_MSG_WARN([doxygen version $doxy_ver too old, doxygen will not be used.])
+   enable_doc=no
+  fi
+ fi
+fi
+
+AM_CONDITIONAL(DOXYGEN_DOC, test x$enable_doc = xyes)
+
+if test x$DOT = x; then
+ if test "x$enable_dot" = xyes; then
+  AC_MSG_ERROR([could not find dot])
+ fi
+ enable_dot=no
+else
+ enable_dot=yes
+fi
+
+AC_SUBST(enable_dot)
+AC_SUBST(enable_html_docs)
+AC_SUBST(enable_latex_docs)
+])