Re: Let parser accept symbols after \new, \context, \unset and implicit \set (issue 13180044)

[dak]

Reviewers: janek,

Message:
On 2013/08/27 07:48:08, janek wrote:
> Looks like a good thing to do, but what does this change mean?

It means it lets the parser accept symbols after \new, \context, \unset
and implicit \set.  After the symbol list changes of issue 2883 (which
made x.y equivalent to #'(x y)), not allowing single symbols in these
places seems like an anachronism.

To wit, \override #'Staff #'NoteHead #'color = #red is proper code,
while \new #'Staff { ... } isn't, but \new #"Staff" { ... } is allowed
again.  That seems like an anachronism.

>   Will we be a)
> able to do things that were previously impossible or b) is there no
user-visible
> difference?
> I think the answer is b), but i'd like to make sure.

I think "Let the parser accept ..." makes pretty clear that we are
talking about extending permitted constructs.

Description:
Let parser accept symbols after \new, \context, \unset and implicit \set

After the symbol list changes of issue 2883, not allowing single
symbols in these places seems like an anachronism.

Please review this at https://codereview.appspot.com/13180044/

Affected files:
  M lily/parser.yy
  M scm/ly-syntax-constructors.scm


Index: lily/parser.yy
diff --git a/lily/parser.yy b/lily/parser.yy
index  
53bddf5eaf64dcf48824e05740d20d330919faab..5ac60f65bc4aa3c3aaf08bc10c494b0bf2a31a09  
100644
--- a/lily/parser.yy
+++ b/lily/parser.yy
@@ -1877,14 +1877,14 @@ complex_music:
        ;

 complex_music_prefix:
-       CONTEXT simple_string optional_id optional_context_mod {
+       CONTEXT symbol optional_id optional_context_mod {
                 Context_mod *ctxmod = unsmob_context_mod ($4);
                 SCM mods = SCM_EOL;
                 if (ctxmod)
                         mods = ctxmod->get_mods ();
 		$$ = START_MAKE_SYNTAX ("context-specification", $2, $3, mods,  
SCM_BOOL_F);
        }
-       | NEWCONTEXT simple_string optional_id optional_context_mod {
+       | NEWCONTEXT symbol optional_id optional_context_mod {
                 Context_mod *ctxmod = unsmob_context_mod ($4);
                 SCM mods = SCM_EOL;
                 if (ctxmod)
@@ -2024,13 +2024,11 @@ property_path:
        ;

 property_operation:
-       STRING '=' scalar {
-               $$ = scm_list_3 (ly_symbol2scm ("assign"),
-                       scm_string_to_symbol ($1), $3);
+       symbol '=' scalar {
+               $$ = scm_list_3 (ly_symbol2scm ("assign"), $1, $3);
        }
-       | UNSET simple_string {
-               $$ = scm_list_2 (ly_symbol2scm ("unset"),
-                       scm_string_to_symbol ($2));
+       | UNSET symbol {
+               $$ = scm_list_2 (ly_symbol2scm ("unset"), $2);
        }
        | OVERRIDE property_path '=' scalar {
                if (scm_ilength ($2) < 2) {
@@ -2296,6 +2294,26 @@ simple_string: STRING {
        }
        ;

+symbol:
+       STRING {
+               $$ = scm_string_to_symbol ($1);
+       }
+       | embedded_scm_bare
+       {
+               // This is a bit of overkill but makes the same
+               // routine responsible for all symbol interpretations.
+               $$ = try_string_variants (ly_lily_module_constant ("symbol?"),
+                                         $1);
+               if (SCM_UNBNDP ($$))
+               {
+                       parser->parser_error (@1, (_ ("symbol expected")));
+                       // Generate a unique symbol in case it is used
+                       // for an assignment or similar
+                       $$ = scm_make_symbol (ly_string2scm ("undefined"));
+               }
+       }
+       ;
+
 scalar:
        embedded_scm_arg
        | SCM_IDENTIFIER
Index: scm/ly-syntax-constructors.scm
diff --git a/scm/ly-syntax-constructors.scm b/scm/ly-syntax-constructors.scm
index  
01fc9bcef820c41cdc6c6add54c9b7459f5efb7c..8b6f4ffefbf01c2ff05fdedce13467e679872e1e  
100644
--- a/scm/ly-syntax-constructors.scm
+++ b/scm/ly-syntax-constructors.scm
@@ -152,8 +152,7 @@ into a @code{MultiMeasureTextEvent}."
               'origin location))

 (define-ly-syntax-simple (context-specification type id ops create-new mus)
-  (let* ((type-sym (if (symbol? type) type (string->symbol type)))
-         (csm (context-spec-music mus type-sym id)))
+  (let ((csm (context-spec-music mus type id)))
     (set! (ly:music-property csm 'property-operations) ops)
     (if create-new (set! (ly:music-property csm 'create-new) #t))
     csm))