[readline] Add CTRL-W shortcut to remove a word

Signed-off-by: Marin Hannache <git@mareo.fr>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/hci/editstring.c

@@ -21,6 +21,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 
 #include <assert.h>
 #include <string.h>
+#include <ctype.h>
 #include <ipxe/keys.h>
 #include <ipxe/editstring.h>
 
@@ -37,6 +38,8 @@ static void insert_character ( struct edit_string *string,
                                unsigned int character ) __nonnull;
 static void delete_character ( struct edit_string *string ) __nonnull;
 static void backspace ( struct edit_string *string ) __nonnull;
+static void previous_word ( struct edit_string *string ) __nonnull;
+static void kill_word ( struct edit_string *string ) __nonnull;
 static void kill_sol ( struct edit_string *string ) __nonnull;
 static void kill_eol ( struct edit_string *string ) __nonnull;
 
@@ -110,10 +113,37 @@ static void backspace ( struct edit_string *string ) {
 	}
 }
 
+/**
+ * Move to start of previous word
+ *
+ * @v string		Editable string
+ */
+static void previous_word ( struct edit_string *string ) {
+	while ( string->cursor &&
+		isspace ( string->buf[ string->cursor - 1 ] ) ) {
+		string->cursor--;
+	}
+	while ( string->cursor &&
+		( ! isspace ( string->buf[ string->cursor - 1 ] ) ) ) {
+		string->cursor--;
+	}
+}
+
+/**
+ * Delete to end of previous word
+ *
+ * @v string		Editable string
+ */
+static void kill_word ( struct edit_string *string ) {
+	size_t old_cursor = string->cursor;
+	previous_word ( string );
+	insert_delete ( string, ( old_cursor - string->cursor ), NULL );
+}
+
 /**
  * Delete to start of line
  *
- * @v string           Editable string
+ * @v string		Editable string
  */
 static void kill_sol ( struct edit_string *string ) {
 	size_t old_cursor = string->cursor;
@@ -181,6 +211,10 @@ int edit_string ( struct edit_string *string, int key ) {
 		/* Delete character */
 		delete_character ( string );
 		break;
+	case CTRL_W:
+		/* Delete word */
+		kill_word ( string );
+		break;
 	case CTRL_U:
 		/* Delete to start of line */
 		kill_sol ( string );