next: https://viewsourcecode.org/snaptoken/kilo/03.rawInputAndOutput.…

…html#prevent-moving-the-cursor-off-screen

kilo.c

@@ -15,6 +15,13 @@
 
 #define CTRL_KEY(k) ((k)&0x1f)
 
+enum editorKey {
+  ARROW_LEFT = 1000,
+  ARROW_RIGHT,
+  ARROW_UP,
+  ARROW_DOWN
+};
+
 /*** data ***/
 
 struct editorConfig {
@@ -56,13 +63,36 @@ void enableRawMode() {
   if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) die("tcsetattr");
 }
 
-char editorReadKey() {
+int editorReadKey() {
   int nread;
   char c;
   while ((nread = read(STDIN_FILENO, &c, 1)) != 1) {
     if (nread == -1 && errno != EAGAIN) die("read");
   }
-  return c;
+
+  if (c == '\x1b') {
+    char seq[3];
+
+    if (read(STDIN_FILENO, &seq[0], 1) != 1) return '\x1b';
+    if (read(STDIN_FILENO, &seq[1], 1) != 1) return '\x1b';
+
+    if (seq[0] == '[') {
+      switch (seq[1]) {
+        case 'A':
+          return ARROW_UP;
+        case 'B':
+          return ARROW_DOWN;
+        case 'C':
+          return ARROW_RIGHT;
+        case 'D':
+          return ARROW_LEFT;
+      }
+    }
+
+    return '\x1b';
+  } else {
+    return c;
+  }
 }
 
 int getCursorPosition(int *rows, int *cols) {
@@ -121,25 +151,25 @@ void abFree(struct abuf *ab) {
 
 /*** input ***/
 
-void editorMoveCursor(char key) {
+void editorMoveCursor(int key) {
   switch (key) {
-    case 'a':
+    case ARROW_LEFT:
       E.cx--;
       break;
-    case 'd':
+    case ARROW_RIGHT:
       E.cx++;
       break;
-    case 'w':
+    case ARROW_UP:
       E.cy--;
       break;
-    case 's':
+    case ARROW_DOWN:
       E.cy++;
       break;
   }
 }
 
 void editorProcessKeyPress() {
-  char c = editorReadKey();
+  int c = editorReadKey();
 
   switch (c) {
     case CTRL_KEY('q'):
@@ -148,10 +178,10 @@ void editorProcessKeyPress() {
 
       exit(0);
       break;
-    case 'w':
-    case 's':
-    case 'a':
-    case 'd':
+    case ARROW_UP:
+    case ARROW_DOWN:
+    case ARROW_LEFT:
+    case ARROW_RIGHT:
       editorMoveCursor(c);
       break;
   }