include libslang-1.4.9 and automatically build it and link erlang-slang against it

few (erlang) people will still have libslang-1.4.9 installed or spend time
to get it to link against the driver

1 files changed, 82 insertions, 0 deletions

diff --git a/libslang/slsh/lib/require.sl b/libslang/slsh/lib/require.sl
new file mode 100644
index 0000000..eec1e0d
--- /dev/null
+++ b/libslang/slsh/lib/require.sl
@@ -0,0 +1,82 @@
+% These functions were taken from the jed editor
+
+static variable Features = Assoc_Type [Int_Type,0];
+
+%!%+
+%\function{_featurep}
+%\synopsis{Test whether or not a feature is present}
+%\usage{Int_Type _featurep (String_Type feature)}
+%\description
+%  The \sfun{_featurep} function returns a non-zero value if the specified 
+%  feature is present.  Otherwise, it returns 0 to indicate that the feature
+%  has not been loaded.
+%\seealso{require, provide}
+%!%-
+public define _featurep (f)
+{
+   Features[f];
+}
+
+
+%!%+
+%\function{provide}
+%\synopsis{Declare that a specified feature is available}
+%\usage{provide (String_Type feature)}
+%\description
+% The \sfun{provide} function may be used to declare that a "feature" has 
+% been loaded.  See the documentation for \sfun{require} for more information.
+%\seealso{require, _featurep}
+%!%-
+public define provide (f)
+{
+   Features[f] = 1;
+}
+
+%!%+
+%\function{require}
+%\synopsis{Make sure a feature is present, and load it if not}
+%\usage{require (String_Type feature [,String_Type file]}
+%\description
+%  The \sfun{require} function ensures that a specified "feature" is present.
+%  If the feature is not present, the \sfun{require} function will attempt to
+%  load the feature from a file.  If called with two arguments, the feature
+%  will be loaded from the file specified by the second argument.  Otherwise,
+%  the feature will be loaded from a file given by the name of the feature, 
+%  with ".sl" appended.
+%  
+%  If after loading the file, if the feature is not present, 
+%  a warning message will be issued.
+%\notes
+%  "feature" is an abstract quantity that is undefined here.
+%  
+%  A popular use of the \sfun{require} function is to ensure that a specified
+%  file has already been loaded.  In this case, the feature is the 
+%  filename itself.  The advantage of using this mechanism over using 
+%  \ifun{evalfile} is that if the file has already been loaded, \sfun{require}
+%  will not re-load it.  For this to work, the file must indicate that it 
+%  provides the feature via the \sfun{provide} function.
+%\seealso{provide, _featurep, evalfile}
+%!%-
+public define require ()
+{
+   variable f, file;
+
+   if (_NARGS == 2)
+     {
+	(f, file) = ();
+     }
+   else
+     {
+	f = ();
+	file = f;
+     }
+
+   if (_featurep (f))
+     return;
+
+   () = evalfile (file);
+   !if (_featurep (f))
+     vmessage ("***Warning: feature %s not found in %s", f, file);
+}
+
+