Improve Ruby support in 'etags'

* lib-src/etags.c (Ruby_functions): Tag constants.  Don't tag
singleton classes.  Remove class qualifiers from tags generated
for method and constant names.  (Bug#22241)

* doc/emacs/maintaining.texi (Tag Syntax): Mention that constants
are tagged by etags in Ruby.

* etc/NEWS: Mention that constants are tagged by etags in Ruby.

* test/etags/ruby-src/test1.ruby: Add more tests.
* test/etags/ETAGS.good_1:
* test/etags/ETAGS.good_2:
* test/etags/ETAGS.good_3:
* test/etags/ETAGS.good_4:
* test/etags/ETAGS.good_5:
* test/etags/ETAGS.good_6:
* test/etags/CTAGS.good: Adapt to the changes in etags and in Ruby
tests.

1 files changed, 54 insertions, 4 deletions

diff --git a/lib-src/etags.c b/lib-src/etags.c
index 54ed1b428e9..adc08a23678 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -4550,18 +4550,68 @@ Ruby_functions (FILE *inf)
 
   LOOP_ON_INPUT_LINES (inf, lb, cp)
     {
+      bool is_class = false;
+      bool is_method = false;
+      char *name;
+
       cp = skip_spaces (cp);
-      if (LOOKING_AT (cp, "def")
-          || LOOKING_AT (cp, "class")
-          || LOOKING_AT (cp, "module"))
+      if (c_isalpha (*cp) && c_isupper (*cp)) /* constants */
         {
-          char *name = cp;
+          char *bp, *colon = NULL;
+
+          name = cp;
+
+          for (cp++; c_isalnum (*cp) || *cp == '_' || *cp == ':'; cp++)
+            {
+              if (*cp == ':')
+                colon = cp;
+            }
+          if (cp > name + 1)
+            {
+              bp = skip_spaces (cp);
+              if (*bp == '=' && c_isspace (bp[1]))
+                {
+                  if (colon && !c_isspace (colon[1]))
+                    name = colon + 1;
+                  make_tag (name, cp - name, false,
+                            lb.buffer, cp - lb.buffer + 1, lineno, linecharno);
+                }
+            }
+        }
+      else if ((is_method = LOOKING_AT (cp, "def")) /* module/class/method */
+               || (is_class = LOOKING_AT (cp, "class"))
+               || LOOKING_AT (cp, "module"))
+        {
+          const char self_name[] = "self.";
+          const size_t self_size1 = sizeof ("self.") - 1;
+
+          name = cp;
 
          /* Ruby method names can end in a '='.  Also, operator overloading can
             define operators whose names include '='.  */
           while (!notinname (*cp) || *cp == '=')
             cp++;
 
+          /* Remove "self." from the method name.  */
+          if (cp - name > self_size1
+              && strneq (name, self_name, self_size1))
+            name += self_size1;
+
+          /* Remove the class/module qualifiers from method names.  */
+          if (is_method)
+            {
+              char *q;
+
+              for (q = name; q < cp && *q != '.'; q++)
+                ;
+              if (q < cp - 1)   /* punt if we see just "FOO." */
+                name = q + 1;
+            }
+
+          /* Don't tag singleton classes.  */
+          if (is_class && strneq (name, "<<", 2) && cp == name + 2)
+            continue;
+
           make_tag (name, cp - name, true,
                     lb.buffer, cp - lb.buffer + 1, lineno, linecharno);
         }