shell: add meta-keys

Added following meta-keys:
Ctrl-B - moves the cursor backward one character
Ctrl-D - deletes the character under the cursor
Ctrl-F - moves the cursor forward one character
Ctrl-K - deletes from the cursor to the end of the line
Alt-F  - moves the cursor forward one word
Alt-B  - moves the cursor backward one word

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>

subsys/shell/shell.c

@@ -768,7 +768,20 @@ static void tab_handle(const struct shell *shell)
 	}
 }
 
-static void metakeys_handle(const struct shell *shell, char data)
+static void alt_metakeys_handle(const struct shell *shell, char data)
+{
+	/* Optional feature */
+	if (!IS_ENABLED(CONFIG_SHELL_METAKEYS)) {
+		return;
+	}
+	if (data == SHELL_VT100_ASCII_ALT_B) {
+		shell_op_cursor_word_move(shell, -1);
+	} else if (data == SHELL_VT100_ASCII_ALT_F) {
+		shell_op_cursor_word_move(shell, 1);
+	}
+}
+
+static void ctrl_metakeys_handle(const struct shell *shell, char data)
 {
 	/* Optional feature */
 	if (!IS_ENABLED(CONFIG_SHELL_METAKEYS)) {
@@ -780,6 +793,10 @@ static void metakeys_handle(const struct shell *shell, char data)
 		shell_op_cursor_home_move(shell);
 		break;
 
+	case SHELL_VT100_ASCII_CTRL_B: /* CTRL + B */
+		shell_op_left_arrow(shell);
+		break;
+
 	case SHELL_VT100_ASCII_CTRL_C: /* CTRL + C */
 		shell_op_cursor_end_move(shell);
 		if (!shell_cursor_in_empty_line(shell)) {
@@ -789,10 +806,22 @@ static void metakeys_handle(const struct shell *shell, char data)
 		state_set(shell, SHELL_STATE_ACTIVE);
 		break;
 
+	case SHELL_VT100_ASCII_CTRL_D: /* CTRL + D */
+		shell_op_char_delete(shell);
+		break;
+
 	case SHELL_VT100_ASCII_CTRL_E: /* CTRL + E */
 		shell_op_cursor_end_move(shell);
 		break;
 
+	case SHELL_VT100_ASCII_CTRL_F: /* CTRL + F */
+		shell_op_right_arrow(shell);
+		break;
+
+	case SHELL_VT100_ASCII_CTRL_K: /* CTRL + K */
+		shell_op_delete_from_cursor(shell);
+		break;
+
 	case SHELL_VT100_ASCII_CTRL_L: /* CTRL + L */
 		SHELL_VT100_CMD(shell, SHELL_VT100_CURSORHOME);
 		SHELL_VT100_CMD(shell, SHELL_VT100_CLEARSCREEN);
@@ -921,7 +950,7 @@ static void state_collect(const struct shell *shell)
 					flag_history_exit_set(shell, true);
 					shell_op_char_insert(shell, data);
 				} else {
-					metakeys_handle(shell, data);
+					ctrl_metakeys_handle(shell, data);
 				}
 				break;
 			}
@@ -932,6 +961,7 @@ static void state_collect(const struct shell *shell)
 				receive_state_change(shell,
 						SHELL_RECEIVE_ESC_SEQ);
 			} else {
+				alt_metakeys_handle(shell, data);
 				receive_state_change(shell,
 						SHELL_RECEIVE_DEFAULT);
 			}

subsys/shell/shell_ops.c

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <ctype.h>
 #include "shell_ops.h"
 
 void shell_op_cursor_vert_move(const struct shell *shell, s32_t delta)
@@ -97,6 +98,51 @@ void shell_op_cursor_move(const struct shell *shell, s16_t val)
 	shell->ctx->cmd_buff_pos = new_pos;
 }
 
+static u16_t shift_calc(const char *str, u16_t pos, u16_t len, s16_t sign)
+{
+	bool found = false;
+	u16_t ret = 0;
+	u16_t idx;
+
+	while (1) {
+		idx = pos + ret * sign;
+		if (((idx == 0) && (sign < 0)) ||
+		    ((idx == len) && (sign > 0))) {
+			break;
+		}
+		if (isalnum((int)str[idx]) != 0) {
+			found = true;
+		} else {
+			if (found) {
+				break;
+			}
+		}
+		ret++;
+	}
+
+	return ret;
+}
+
+void shell_op_cursor_word_move(const struct shell *shell, s16_t val)
+{
+	s16_t shift;
+	s16_t sign;
+
+	if (val < 0) {
+		val = -val;
+		sign = -1;
+	} else {
+		sign = 1;
+	}
+
+	while (val--) {
+		shift = shift_calc(shell->ctx->cmd_buff,
+				   shell->ctx->cmd_buff_pos,
+				   shell->ctx->cmd_buff_len, sign);
+		shell_op_cursor_move(shell, sign * shift);
+	}
+}
+
 void shell_op_word_remove(const struct shell *shell)
 {
 	char *str = &shell->ctx->cmd_buff[shell->ctx->cmd_buff_pos - 1];
@@ -256,6 +302,14 @@ void shell_op_char_delete(const struct shell *shell)
 	reprint_from_cursor(shell, --diff, true);
 }
 
+void shell_op_delete_from_cursor(const struct shell *shell)
+{
+	shell->ctx->cmd_buff_len = shell->ctx->cmd_buff_pos;
+	shell->ctx->cmd_buff[shell->ctx->cmd_buff_pos] = '\0';
+
+	clear_eos(shell);
+}
+
 void shell_op_completion_insert(const struct shell *shell,
 				const char *compl,
 				u16_t compl_len)

subsys/shell/shell_ops.h

@@ -162,6 +162,9 @@ void shell_op_left_arrow(const struct shell *shell);
 
 void shell_op_right_arrow(const struct shell *shell);
 
+/* Moves cursor by defined number of words left (val negative) or right. */
+void shell_op_cursor_word_move(const struct shell *shell, s16_t val);
+
 /*
  *  Removes the "word" to the left of the cursor:
  *  - if there are spaces at the cursor position, remove all spaces to the left
@@ -186,6 +189,8 @@ void shell_op_char_backspace(const struct shell *shell);
 
 void shell_op_char_delete(const struct shell *shell);
 
+void shell_op_delete_from_cursor(const struct shell *shell);
+
 void shell_op_completion_insert(const struct shell *shell,
 				const char *compl,
 				u16_t compl_len);

subsys/shell/shell_vt100.h

@@ -11,11 +11,17 @@
 #define SHELL_VT100_ASCII_DEL		(0x7F)
 #define SHELL_VT100_ASCII_BSPACE	(0x08)
 #define SHELL_VT100_ASCII_CTRL_A	(0x01)
+#define SHELL_VT100_ASCII_CTRL_B	(0x02)
 #define SHELL_VT100_ASCII_CTRL_C	(0x03)
+#define SHELL_VT100_ASCII_CTRL_D	(0x04)
 #define SHELL_VT100_ASCII_CTRL_E	(0x05)
+#define SHELL_VT100_ASCII_CTRL_F	(0x06)
+#define SHELL_VT100_ASCII_CTRL_K	(0x0B)
 #define SHELL_VT100_ASCII_CTRL_L	(0x0C)
 #define SHELL_VT100_ASCII_CTRL_U	(0x15)
 #define SHELL_VT100_ASCII_CTRL_W	(0x17)
+#define SHELL_VT100_ASCII_ALT_B		(0x62)
+#define SHELL_VT100_ASCII_ALT_F		(0x66)
 
 #define SHELL_VT100_SETNL				\
 {							\