Avoid CHA sequence for ANSI.SYS compatibility.
Github user @welash proposed a change in issue #73 in order to improve
the linenoise compatibility with older terminal emulators only able to
deal with a subset of ANSI sequences, notably ANSI.SYS and VT100
terminals strictly able to handle the original set of VT100 escape
sequences.
In order to improve the compatibility, the CHA sequence was removed and
translated to move 999 positions to the left, then move on the right
for the desired number of positions. The CHA sequence was apparently
added only with VT220, that's why it is not available everywhere.
This commit features almost exactly the change proposed in issue #73
with a small fix for a bug in multi-line editing mode introduced by the
patch.
diff --git a/linenoise.c b/linenoise.c
index e864e46..385932b 100644
--- a/linenoise.c
+++ b/linenoise.c
@@ -56,10 +56,6 @@
* flickering effect with some slow terminal, but the lesser sequences
* the more compatible.
*
- * CHA (Cursor Horizontal Absolute)
- * Sequence: ESC [ n G
- * Effect: moves cursor to column n
- *
* EL (Erase Line)
* Sequence: ESC [ n K
* Effect: if n is 0 or missing, clear from cursor to end of line
@@ -68,7 +64,19 @@
*
* CUF (CUrsor Forward)
* Sequence: ESC [ n C
- * Effect: moves cursor forward of n chars
+ * Effect: moves cursor forward n chars
+ *
+ * CUB (CUrsor Backward)
+ * Sequence: ESC [ n D
+ * Effect: moves cursor backward n chars
+ *
+ * The following is used to get the terminal width if getting
+ * the width with the TIOCGWINSZ ioctl fails
+ *
+ * DSR (Device Status Report)
+ * Sequence: ESC [ 6 n
+ * Effect: reports the current cusor position as ESC [ n ; m R
+ * where n is the row and m is the column
*
* When multi line mode is enabled, we also use an additional escape
* sequence. However multi line editing is disabled by default.
@@ -471,7 +479,7 @@
abInit(&ab);
/* Cursor to left edge */
- snprintf(seq,64,"\x1b[0G");
+ snprintf(seq,64,"\x1b[999D");
abAppend(&ab,seq,strlen(seq));
/* Write the prompt and the current buffer content */
abAppend(&ab,l->prompt,strlen(l->prompt));
@@ -480,7 +488,7 @@
snprintf(seq,64,"\x1b[0K");
abAppend(&ab,seq,strlen(seq));
/* Move cursor to original position. */
- snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
+ snprintf(seq,64,"\x1b[999D\x1b[%dC", (int)(pos+plen));
abAppend(&ab,seq,strlen(seq));
if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
abFree(&ab);
@@ -515,13 +523,13 @@
/* Now for every row clear it, go up. */
for (j = 0; j < old_rows-1; j++) {
lndebug("clear+up");
- snprintf(seq,64,"\x1b[0G\x1b[0K\x1b[1A");
+ snprintf(seq,64,"\x1b[999D\x1b[0K\x1b[1A");
abAppend(&ab,seq,strlen(seq));
}
/* Clean the top line. */
lndebug("clear");
- snprintf(seq,64,"\x1b[0G\x1b[0K");
+ snprintf(seq,64,"\x1b[999D\x1b[0K");
abAppend(&ab,seq,strlen(seq));
/* Write the prompt and the current buffer content */
@@ -536,7 +544,7 @@
{
lndebug("<newline>");
abAppend(&ab,"\n",1);
- snprintf(seq,64,"\x1b[0G");
+ snprintf(seq,64,"\x1b[999D");
abAppend(&ab,seq,strlen(seq));
rows++;
if (rows > (int)l->maxrows) l->maxrows = rows;
@@ -555,7 +563,7 @@
/* Set column. */
lndebug("set col %d", 1+((plen+(int)l->pos) % (int)l->cols));
- snprintf(seq,64,"\x1b[%dG", 1+((plen+(int)l->pos) % (int)l->cols));
+ snprintf(seq,64,"\x1b[999D\x1b[%dC", (plen+(int)l->pos) % (int)l->cols);
abAppend(&ab,seq,strlen(seq));
lndebug("\n");
@@ -904,7 +912,7 @@
printf("'%c' %02x (%d) (type quit to exit)\n",
isprint(c) ? c : '?', (int)c, (int)c);
- printf("\x1b[0G"); /* Go left edge manually, we are in raw mode. */
+ printf("\x1b[999D"); /* Go left edge manually, we are in raw mode. */
fflush(stdout);
}
disableRawMode(STDIN_FILENO);
