vim-patch:8.0.0630: it is not easy to work on lines without a match (#8734)

Problem:    The :global command does not work recursively, which makes it
            difficult to execute a command on a line where one pattern matches
            and another does not match. (Miles Cranmer)
Solution:   Allow for recursion if it is for only one line. (closes vim/vim#1760)
f84b122a99

runtime/doc/repeat.txt

@@ -37,7 +37,7 @@ of area is used, see |visual-repeat|.
 ==============================================================================
 2. Multiple repeats					*multi-repeat*
 
-						*:g* *:global* *E147* *E148*
+						*:g* *:global* *E148*
 :[range]g[lobal]/{pattern}/[cmd]
 			Execute the Ex command [cmd] (default ":p") on the
 			lines within [range] where {pattern} matches.
@@ -70,8 +70,15 @@ The default for [range] is the whole buffer (1,$).  Use "CTRL-C" to interrupt
 the command.  If an error message is given for a line, the command for that
 line is aborted and the global command continues with the next marked or
 unmarked line.
+								*E147* 
+When the command is used recursively, it only works on one line.  Giving a
+range is then not allowed. This is useful to find all lines that match a
+pattern and do not match another pattern: >
+	:g/found/v/notfound/{cmd}
+This first finds all lines containing "found", but only executes {cmd} when
+there is no match for "notfound".
 
-To repeat a non-Ex command, you can use the ":normal" command: >
+To execute a non-Ex command, you can use the `:normal` command: >
 	:g/pat/normal {commands}
 Make sure that {commands} ends with a whole command, otherwise Vim will wait
 for you to type the rest of the command for each match.  The screen will not

src/nvim/ex_cmds.c

@@ -4176,6 +4176,17 @@ do_sub_msg (
   return false;
 }
 
+static void global_exe_one(char_u *const cmd, const linenr_T lnum)
+{
+  curwin->w_cursor.lnum = lnum;
+  curwin->w_cursor.col = 0;
+  if (*cmd == NUL || *cmd == '\n') {
+    do_cmdline((char_u *)"p", NULL, NULL, DOCMD_NOWAIT);
+  } else {
+    do_cmdline(cmd, NULL, NULL, DOCMD_NOWAIT);
+  }
+}
+
 /*
  * Execute a global command of the form:
  *
@@ -4205,8 +4216,12 @@ void ex_global(exarg_T *eap)
   int match;
   int which_pat;
 
-  if (global_busy) {
-    EMSG(_("E147: Cannot do :global recursive"));       /* will increment global_busy */
+  // When nesting the command works on one line.  This allows for
+  // ":g/found/v/notfound/command".
+  if (global_busy && (eap->line1 != 1
+                      || eap->line2 != curbuf->b_ml.ml_line_count)) {
+    // will increment global_busy to break out of the loop
+    EMSG(_("E147: Cannot do :global recursive with a range"));
     return;
   }
 
@@ -4255,11 +4270,17 @@ void ex_global(exarg_T *eap)
     return;
   }
 
-  /*
-   * pass 1: set marks for each (not) matching line
-   */
-  for (lnum = eap->line1; lnum <= eap->line2 && !got_int; ++lnum) {
-    /* a match on this line? */
+  if (global_busy) {
+    lnum = curwin->w_cursor.lnum;
+    match = vim_regexec_multi(&regmatch, curwin, curbuf, lnum,
+                              (colnr_T)0, NULL);
+    if ((type == 'g' && match) || (type == 'v' && !match)) {
+      global_exe_one(cmd, lnum);
+    }
+  } else {
+    // pass 1: set marks for each (not) matching line
+    for (lnum = eap->line1; lnum <= eap->line2 && !got_int; lnum++) {
+      // a match on this line?
       match = vim_regexec_multi(&regmatch, curwin, curbuf, lnum,
                                 (colnr_T)0, NULL);
       if ((type == 'g' && match) || (type == 'v' && !match)) {
@@ -4269,12 +4290,10 @@ void ex_global(exarg_T *eap)
       line_breakcheck();
     }
 
-  /*
-   * pass 2: execute the command for each line that has been marked
-   */
-  if (got_int)
+    // pass 2: execute the command for each line that has been marked
+    if (got_int) {
       MSG(_(e_interr));
-  else if (ndone == 0) {
+    } else if (ndone == 0) {
       if (type == 'v') {
         smsg(_("Pattern found in every line: %s"), pat);
       } else {
@@ -4283,7 +4302,8 @@ void ex_global(exarg_T *eap)
     } else {
       global_exe(cmd);
     }
-  ml_clearmarked();        /* clear rest of the marks */
+    ml_clearmarked();         // clear rest of the marks
+  }
   vim_regfree(regmatch.regprog);
 }
 
@@ -4312,13 +4332,7 @@ void global_exe(char_u *cmd)
   old_lcount = curbuf->b_ml.ml_line_count;
 
   while (!got_int && (lnum = ml_firstmarked()) != 0 && global_busy == 1) {
-    curwin->w_cursor.lnum = lnum;
-    curwin->w_cursor.col = 0;
-    if (*cmd == NUL || *cmd == '\n') {
-      do_cmdline((char_u *)"p", NULL, NULL, DOCMD_NOWAIT);
-    } else {
-      do_cmdline(cmd, NULL, NULL, DOCMD_NOWAIT);
-    }
+    global_exe_one(cmd, lnum);
     os_breakcheck();
   }
 

src/nvim/testdir/test_global.vim

@@ -9,3 +9,12 @@ func Test_yank_put_clipboard()
   set clipboard&
   bwipe!
 endfunc
+
+func Test_nested_global()
+  new
+  call setline(1, ['nothing', 'found', 'found bad', 'bad'])
+  call assert_fails('g/found/3v/bad/s/^/++/', 'E147')
+  g/found/v/bad/s/^/++/
+  call assert_equal(['nothing', '++found', 'found bad', 'bad'], getline(1, 4))
+  bwipe!
+endfunc