move to first non-whitespace on next line

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.15)
 project(ke C)  # Specify C language explicitly
 
 set(CMAKE_C_STANDARD 99)
-set(KE_VERSION "1.3.3")
+set(KE_VERSION "1.3.4")
 
 set(CMAKE_C_FLAGS "-Wall -Wextra -pedantic -Wshadow -Werror -std=c99 -g")
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_DEFAULT_SOURCE -D_XOPEN_SOURCE")

default.nix

@@ -6,7 +6,7 @@
 }:
 stdenv.mkDerivation {
   pname = "ke";
-  version = "1.3.3";
+  version = "1.3.4";
 
   src = lib.cleanSource ./.;
 

main.c

@@ -21,6 +21,7 @@
 #include <string.h>
 #include <locale.h>
 #include <wchar.h>
+#include <wctype.h>
 #include <termios.h>
 #include <time.h>
 #include <unistd.h>
@@ -1589,6 +1590,41 @@ editor_openfile(void)
 }
 
 
+int
+first_nonwhitespace(struct erow *row)
+{
+	int pos;
+	wchar_t wc;
+	mbstate_t state;
+	size_t len;
+
+	if (row == NULL) {
+		return 0;
+	}
+
+	memset(&state, 0, sizeof(state));
+	pos = 0;
+	while (pos < row->size) {
+		len = mbrtowc(&wc, &row->line[pos], row->size - pos, &state);
+		if (len == (size_t) -1 || len == (size_t) -2) {
+			/* Invalid or incomplete sequence, stop here */
+			break;
+		}
+		if (len == 0) {
+			/* Null character, stop here */
+			break;
+		}
+		if (!iswspace(wc)) {
+			/* Found non-whitespace character */
+			break;
+		}
+		pos += len;
+	}
+
+	return pos;
+}
+
+
 void
 move_cursor(int16_t c)
 {
@@ -1602,12 +1638,20 @@ move_cursor(int16_t c)
 	case CTRL_KEY('p'):
 		if (editor.cury > 0) {
 			editor.cury--;
+			row = (editor.cury >= editor.nrows)
+				      ? NULL
+				      : &editor.row[editor.cury];
+			editor.curx = first_nonwhitespace(row);
 		}
 		break;
 	case ARROW_DOWN:
 	case CTRL_KEY('n'):
 		if (editor.cury < editor.nrows) {
 			editor.cury++;
+			row = (editor.cury >= editor.nrows)
+				      ? NULL
+				      : &editor.row[editor.cury];
+			editor.curx = first_nonwhitespace(row);
 		}
 		break;
 	case ARROW_RIGHT:
@@ -1622,7 +1666,10 @@ move_cursor(int16_t c)
 			}
 		} else if (row && editor.curx == row->size) {
 			editor.cury++;
-				editor.curx = 0;
+			row = (editor.cury >= editor.nrows)
+				      ? NULL
+				      : &editor.row[editor.cury];
+			editor.curx = first_nonwhitespace(row);
 		}
 		break;
 	case ARROW_LEFT: