vi: improvements to undo

The left shift operator ('<') didn't support undo at all; right
shift ('>') required changes to be undone separately for each line.
Allow both types of shift to be undone as a single operation.

Also, neither traditional vi nor vim yank the lines being shifted by
the '<' and '>' commands, so remove that call to yank_delete();

When a repetition count was specified for the '~', 'x', 'X' or 's'
commands the changes had to be undone one character at a time.
Allow undo as a single operation (though the delete and change
parts of the 's' command still have to be undone separately).

function                                             old     new   delta
undo_push_insert                                      37      40      +3
do_cmd                                              4695    4663     -32
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 3/-32)             Total: -29 bytes

v2: Don't break build when FEATURE_VI_UNDO is  disabled.  Don't reset
    'undo_del' too early in '~' handling code.  Code shrink '~'.

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 22 insertions, 13 deletions

diff --git a/editors/vi.c b/editors/vi.c
index 7e89f58da..e752685d8 100644
--- a/editors/vi.c
+++ b/editors/vi.c
@@ -3213,6 +3213,10 @@ static void do_cmd(int c)
         int dir;
         int cnt, i, j;
         int c1;
+#if ENABLE_FEATURE_VI_UNDO
+        int allow_undo = ALLOW_UNDO;
+        int undo_del = UNDO_DEL;
+#endif
 
 //      c1 = c; // quiet the compiler
 //      cnt = yf = 0; // quiet the compiler
@@ -3614,24 +3618,29 @@ static void do_cmd(int c)
                 cnt = count_lines(text, dot);   // remember what line we are on
                 if (find_range(&p, &q, c) == -1)
                         goto dc6;
-                yank_delete(p, q, WHOLE, YANKONLY, NO_UNDO);    // save copy before change
                 i = count_lines(p, q);  // # of lines we are shifting
                 for ( ; i > 0; i--, p = next_line(p)) {
                         if (c == '<') {
                                 // shift left- remove tab or 8 spaces
                                 if (*p == '\t') {
                                         // shrink buffer 1 char
-                                        text_hole_delete(p, p, NO_UNDO);
+                                        text_hole_delete(p, p, allow_undo);
                                 } else if (*p == ' ') {
                                         // we should be calculating columns, not just SPACE
                                         for (j = 0; *p == ' ' && j < tabstop; j++) {
-                                                text_hole_delete(p, p, NO_UNDO);
+                                                text_hole_delete(p, p, allow_undo);
+#if ENABLE_FEATURE_VI_UNDO
+                                                allow_undo = ALLOW_UNDO_CHAIN;
+#endif
                                         }
                                 }
-                        } else if (c == '>') {
+                        } else /* if (c == '>') */ {
                                 // shift right -- add tab or 8 spaces
-                                char_insert(p, '\t', ALLOW_UNDO);
+                                char_insert(p, '\t', allow_undo);
                         }
+#if ENABLE_FEATURE_VI_UNDO
+                        allow_undo = ALLOW_UNDO_CHAIN;
+#endif
                 }
                 dot = find_line(cnt);   // what line were we on
                 dot_skip_over_ws();
@@ -3785,7 +3794,10 @@ static void do_cmd(int c)
                         if (dot[dir] != '\n') {
                                 if (c == 'X')
                                         dot--;  // delete prev char
-                                dot = yank_delete(dot, dot, PARTIAL, YANKDEL, ALLOW_UNDO);      // delete char
+                                dot = yank_delete(dot, dot, PARTIAL, YANKDEL, allow_undo);      // delete char
+#if ENABLE_FEATURE_VI_UNDO
+                                allow_undo = ALLOW_UNDO_CHAIN;
+#endif
                         }
                 } while (--cmdcnt > 0);
                 end_cmd_q();    // stop adding to q
@@ -3945,14 +3957,11 @@ static void do_cmd(int c)
         case '~':                       // ~- flip the case of letters   a-z -> A-Z
                 do {
 #if ENABLE_FEATURE_VI_UNDO
-                        if (islower(*dot)) {
-                                undo_push(dot, 1, UNDO_DEL);
-                                *dot = toupper(*dot);
-                                undo_push(dot, 1, UNDO_INS_CHAIN);
-                        } else if (isupper(*dot)) {
-                                undo_push(dot, 1, UNDO_DEL);
-                                *dot = tolower(*dot);
+                        if (isalpha(*dot)) {
+                                undo_push(dot, 1, undo_del);
+                                *dot = islower(*dot) ? toupper(*dot) : tolower(*dot);
                                 undo_push(dot, 1, UNDO_INS_CHAIN);
+                                undo_del = UNDO_DEL_CHAIN;
                         }
 #else
                         if (islower(*dot)) {