geadline: move cursor

src/geadline.🗿

@@ -3,11 +3,13 @@ geadline(prompt) {
 	      size = 0,
 	      i = 0,
 	      c,
+	      a,
 	      buf = galloc(capacity);
 	if (prompt)
 		putstr(prompt);
 	if (buf == NULL)
 		return NULL;
+	[buf] = 0;
 
 	loop {
 		red &c;
@@ -16,34 +18,94 @@ geadline(prompt) {
 				free(buf);
 				return 0;
 			}
-		} else if (c == 0x007f) {
-			if (size) {
+		} else if (c == 0x1b) {
+			// ESC code
+			red &c; // skip [
+			red &c; // value
+
+			if ((c == 'A') & (size > 0)) {
+				loop {
+					if (i == 0)
+						break;
+					i = i - 1;
+					esccode('D');
+				}
+			} else if ((c == 'B') & (i < size)) {
+				loop {
+					if (i >= size)
+						break;
+					i = i + 1;
+					esccode('C');
+				}
+			} else if ((c == 'C') & (i < size)) {
+				i = i + 1;
+				esccode('C');
+			} else if ((c == 'D') & (i > 0)) {
+				i = i - 1;
+				esccode('D');
+			}
+				wrt '\a';
+		} else if (c == 0x7f) {
+			if (i) {
+				a = i - 1;
+				loop {
+					if (a >= size)
+						break;
+					[buf + a] = [buf + a + 1];
+					a = a + 1;
+				}
 				size = size - 1;
 				i = i - 1;
 				[buf + size] = 0;
 
-				wrt 0x1b;
-				wrt 0x5b;
-				wrt 0x44;
+				wrt '\r';
+				if (prompt)
+					putstr(prompt);
+				putstr(buf);
 				wrt ' ';
-				wrt 0x1b;
-				wrt 0x5b;
-				wrt 0x44;
+				esccode('D');
+				a = size - i;
+				loop {
+					if (a == 0)
+						break;
+					a = a - 1;
+					esccode('D');
+				}
 			}
 		} else {
 			size = size + 1;
-			if (size > capacity) {
+			if (size >= capacity) {
 				buf = realloc(buf, capacity * 2);
 				if (buf == NULL)
 					return NULL;
 				capacity = capacity * 2;
 			}
+			a = size - i - 1;
+			loop {
+				if ((a == 0xffff) | (a == 0))
+					break;
+				[buf + i + a] = [buf + i + a - 1];
+				a = a - 1;
+			}
 			[buf + i] = c;
+			[buf + size] = 0;
+			putstr(buf + i);
+			a = strlen(buf + i) - 1;
+			loop {
+				if ((a == 0xffff) | (a == 0))
+					break;
+				a = a - 1;
+				esccode('D');
+			}
 			i = i + 1;
-			[buf + i] = 0;
-			wrt c;
 			if (c == '\n')
 				return buf;
 		}
 	}
 }
+
+esccode(c) {
+	wrt 0x1b;
+	wrt '[';
+	wrt c;
+}