[PATCH 09/16] Allow the string "xxx.yyy" to parse as a symbol list

[David Kastrup]

This changes the parser to let xxx.yyy be a valid way of specifying a
function argument required to be #'(xxx yyy).
---
 lily/parser.yy |   48 ++++++++++++++++++++++++++++++++++--------------
 1 file changed, 34 insertions(+), 14 deletions(-)

diff --git a/lily/parser.yy b/lily/parser.yy
index 6a087d8..121b059 100644
--- a/lily/parser.yy
+++ b/lily/parser.yy
@@ -231,7 +231,7 @@ SCM make_chord_elements (Input loc, SCM pitch, SCM dur, SCM 
modification_list);
 SCM make_chord_step (SCM step, Rational alter);
 SCM make_simple_markup (SCM a);
 bool is_duration (int t);
-bool is_regular_identifier (SCM id);
+bool is_regular_identifier (SCM id, bool multiple=false);
 SCM try_string_variants (SCM pred, SCM str);
 int yylex (YYSTYPE *s, YYLTYPE *loc, Lily_parser *parser);
 
@@ -1309,15 +1309,15 @@ symbol_list_part:
        symbol_list_element
        {
                SCM sym_l_p = ly_lily_module_constant ("symbol-list?");
-               if (scm_is_true (scm_call_1 (sym_l_p, $1)))
-                       $$ = scm_reverse ($1);
-               else {
+               if (scm_is_false (scm_call_1 (sym_l_p, $1)))
+               {
                        $$ = try_string_variants (sym_l_p, $1);
                        if (SCM_UNBNDP ($$)) {
                                parser->parser_error (@1, _("not a symbol"));
                                $$ = SCM_EOL;
                        }
                }
+               $$ = scm_reverse ($$);
        }
        ;
 
@@ -3413,27 +3413,47 @@ SCM loc_on_music (Input loc, SCM arg)
 SCM
 try_string_variants (SCM pred, SCM str)
 {
+       // a matching predicate is always ok
        if (scm_is_true (scm_call_1 (pred, str)))
                return str;
-       if (scm_is_string (str))
-       {
-               if (!is_regular_identifier (str))
-                       return SCM_UNDEFINED;
-
-               str = scm_string_to_symbol (str);
+       // a symbol may be interpreted as a list of symbols if it helps
+       if (scm_is_symbol (str)) {
+               str = scm_list_1 (str);
                if (scm_is_true (scm_call_1 (pred, str)))
                        return str;
-       } else if (!scm_is_symbol (str))
                return SCM_UNDEFINED;
+       }
+
+       // If this cannot be a string representation of a symbol list,
+       // we are through.
+
+       if (!is_regular_identifier (str, true))
+               return SCM_UNDEFINED;
+
+       str = scm_string_split (str, SCM_MAKE_CHAR ('.'));
+       for (SCM p = str; scm_is_pair (p); p = scm_cdr (p))
+               scm_set_car_x (p, scm_string_to_symbol (scm_car (p)));
+
+       // Let's attempt the symbol list interpretation first.
 
-       str = scm_list_1 (str);
        if (scm_is_true (scm_call_1 (pred, str)))
                return str;
+
+       // If there is just one symbol in the list, we might interpret
+       // it as a single symbol
+
+       if (scm_is_null (scm_cdr (str)))
+       {
+               str = scm_car (str);
+               if (scm_is_true (scm_call_1 (pred, str)))
+                       return str;
+       }
+
        return SCM_UNDEFINED;
 }
 
 bool
-is_regular_identifier (SCM id)
+is_regular_identifier (SCM id, bool multiple)
 {
   if (!scm_is_string (id))
          return false;
@@ -3449,7 +3469,7 @@ is_regular_identifier (SCM id)
              || (c >= 'A' && c <= 'Z')
              || c > 0x7f)
                  middle = true;
-         else if (middle && (c == '-' || c == '_'))
+         else if (middle && (c == '-' || c == '_' || (multiple && c == '.')))
                  middle = false;
          else
                  return false;
-- 
1.7.9.5