bug#259: delphi-mode does not properly format interface definitions

[Simon South <ssouth@slowcomputing.org>]

Stefan Monnier wrote:
> Can someone confirm whether this patch does the right thing?

It doesn't.  I've pasted a short program listing below to test with. 
The patch I submitted will make delphi-mode indent the definition of 
TestInterface correctly, except that *everything* between the first 
instance of "interface" and "implementation" is indented one tab space 
too far to the right.

The solution will be to have delphi-mode identify "interface", on its 
own, as a unit section, and "= interface" as the start of an interface 
definition.  My patch makes the function "delphi-composite-type-start" 
identify "= interface" as a composite type, so that's part of it done. 
However, this seems to get overridden in delphi-enclosing-indent-of: As 
I understand it, as the function parses the line it first identifies "= 
interface" as a composite type and sets the indentation properly, but 
then later parses "interface" again on its own and cancels the 
indentation.  (My patch makes the function ignore "interface" the second 
time so the indentation never gets cancelled, but then that triggers the 
problem illustrated by the code sample below.)

The fix may be as simple as making delphi-enclosing-indent-of interpret 
"interface" as a unit section only if an equals sign wasn't previously 
parsed, especially as there already seems to be some logic to do this 
(see how the "equals-encountered" variable is used).  But my LISPmanship 
is poor and I couldn't get this to work myself.

I'll take another stab at it this weekend, but if someone monitoring 
this list has experience with programming modes and is looking for an 
easy enhancement to make, this could be it...

---

{ Sample unit for testing emacs bug #259, "delphi-mode does not
   properly format interface definitions.  This shows the correct
   indentation. }
unit TestIndentation;

interface

function TestFunction: String;

type
   TestInterface = interface
     function TestInterfaceFunction: String;
   end;

implementation

function TestFunction: String;
begin
   Result := 'Test Function Output';
end;

end.

-- 
Simon South
ssouth@slowcomputing.org