lib/mp-readline: Add word-based move/delete EMACS key sequences.

This commit adds backward-word, backward-kill-word, forward-word,
forward-kill-word sequences for the REPL, with bindings to Alt+F, Alt+B,
Alt+D and Alt+Backspace respectively.  It is disabled by default and can be
enabled via MICROPY_REPL_EMACS_WORDS_MOVE.

Further enabling MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE adds extra bindings
for these new sequences: Ctrl+Right, Ctrl+Left and Ctrl+W.

The features are enabled on unix micropython-coverage and micropython-dev.

10 files changed, 202 insertions, 1 deletions

diff --git a/lib/mp-readline/readline.c b/lib/mp-readline/readline.c
index 1500873f6..296c8aa4a 100644
--- a/lib/mp-readline/readline.c
+++ b/lib/mp-readline/readline.c
@@ -99,6 +99,35 @@ typedef struct _readline_t {
 
 STATIC readline_t rl;
 
+#if MICROPY_REPL_EMACS_WORDS_MOVE
+STATIC size_t cursor_count_word(int forward) {
+    const char *line_buf = vstr_str(rl.line);
+    size_t pos = rl.cursor_pos;
+    bool in_word = false;
+
+    for (;;) {
+        // if moving backwards and we've reached 0... break
+        if (!forward && pos == 0) {
+            break;
+        }
+        // or if moving forwards and we've reached to the end of line... break
+        else if (forward && pos == vstr_len(rl.line)) {
+            break;
+        }
+
+        if (unichar_isalnum(line_buf[pos + (forward - 1)])) {
+            in_word = true;
+        } else if (in_word) {
+            break;
+        }
+
+        pos += forward ? forward : -1;
+    }
+
+    return forward ? pos - rl.cursor_pos : rl.cursor_pos - pos;
+}
+#endif
+
 int readline_process_char(int c) {
     size_t last_line_len = rl.line->len;
     int redraw_step_back = 0;
@@ -149,6 +178,10 @@ int readline_process_char(int c) {
             redraw_step_back = rl.cursor_pos - rl.orig_line_len;
             redraw_from_cursor = true;
         #endif
+        #if MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+        } else if (c == CHAR_CTRL_W) {
+            goto backward_kill_word;
+        #endif
         } else if (c == '\r') {
             // newline
             mp_hal_stdout_tx_str("\r\n");
@@ -222,9 +255,40 @@ int readline_process_char(int c) {
             case 'O':
                 rl.escape_seq = ESEQ_ESC_O;
                 break;
+            #if MICROPY_REPL_EMACS_WORDS_MOVE
+            case 'b':
+#if MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+backward_word:
+#endif
+                redraw_step_back = cursor_count_word(0);
+                rl.escape_seq = ESEQ_NONE;
+                break;
+            case 'f':
+#if MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+forward_word:
+#endif
+                redraw_step_forward = cursor_count_word(1);
+                rl.escape_seq = ESEQ_NONE;
+                break;
+            case 'd':
+                vstr_cut_out_bytes(rl.line, rl.cursor_pos, cursor_count_word(1));
+                redraw_from_cursor = true;
+                rl.escape_seq = ESEQ_NONE;
+                break;
+            case 127:
+#if MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+backward_kill_word:
+#endif
+                redraw_step_back = cursor_count_word(0);
+                vstr_cut_out_bytes(rl.line, rl.cursor_pos - redraw_step_back, redraw_step_back);
+                redraw_from_cursor = true;
+                rl.escape_seq = ESEQ_NONE;
+                break;
+            #endif
             default:
                 DEBUG_printf("(ESC %d)", c);
                 rl.escape_seq = ESEQ_NONE;
+                break;
         }
     } else if (rl.escape_seq == ESEQ_ESC_BRACKET) {
         if ('0' <= c && c <= '9') {
@@ -312,6 +376,24 @@ delete_key:
             } else {
                 DEBUG_printf("(ESC [ %c %d)", rl.escape_seq_buf[0], c);
             }
+        #if MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+        } else if (c == ';' && rl.escape_seq_buf[0] == '1') {
+            // ';' is used to separate parameters. so first parameter was '1',
+            // that's used for sequences like ctrl+left, which we will try to parse.
+            // escape_seq state is reset back to ESEQ_ESC_BRACKET, as if we've just received
+            // the opening bracket, because more parameters are to come.
+            // we don't track the parameters themselves to keep low on logic and code size. that
+            // might be required in the future if more complex sequences are added.
+            rl.escape_seq = ESEQ_ESC_BRACKET;
+            // goto away from the state-machine, as rl.escape_seq will be overridden.
+            goto redraw;
+        } else if (rl.escape_seq_buf[0] == '5' && c == 'C') {
+            // ctrl+right
+            goto forward_word;
+        } else if (rl.escape_seq_buf[0] == '5' && c == 'D') {
+            // ctrl+left
+            goto backward_word;
+        #endif
         } else {
             DEBUG_printf("(ESC [ %c %d)", rl.escape_seq_buf[0], c);
         }
@@ -330,6 +412,10 @@ delete_key:
         rl.escape_seq = ESEQ_NONE;
     }
 
+#if MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+redraw:
+#endif
+
     // redraw command prompt, efficiently
     if (redraw_step_back > 0) {
         mp_hal_move_cursor_back(redraw_step_back);
diff --git a/lib/mp-readline/readline.h b/lib/mp-readline/readline.h
index 00aa9622a..a19e1209a 100644
--- a/lib/mp-readline/readline.h
+++ b/lib/mp-readline/readline.h
@@ -36,6 +36,7 @@
 #define CHAR_CTRL_N (14)
 #define CHAR_CTRL_P (16)
 #define CHAR_CTRL_U (21)
+#define CHAR_CTRL_W (23)
 
 void readline_init0(void);
 int readline(vstr_t *line, const char *prompt);
diff --git a/ports/unix/variants/coverage/mpconfigvariant.h b/ports/unix/variants/coverage/mpconfigvariant.h
index f383a8370..719292453 100644
--- a/ports/unix/variants/coverage/mpconfigvariant.h
+++ b/ports/unix/variants/coverage/mpconfigvariant.h
@@ -34,6 +34,8 @@
 #define MICROPY_FLOAT_HIGH_QUALITY_HASH (1)
 #define MICROPY_ENABLE_SCHEDULER       (1)
 #define MICROPY_READER_VFS             (1)
+#define MICROPY_REPL_EMACS_WORDS_MOVE  (1)
+#define MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE (1)
 #define MICROPY_WARNINGS_CATEGORY      (1)
 #define MICROPY_MODULE_GETATTR         (1)
 #define MICROPY_PY_DELATTR_SETATTR     (1)
diff --git a/ports/unix/variants/dev/mpconfigvariant.h b/ports/unix/variants/dev/mpconfigvariant.h
index 84a3edd45..2b3097010 100644
--- a/ports/unix/variants/dev/mpconfigvariant.h
+++ b/ports/unix/variants/dev/mpconfigvariant.h
@@ -24,4 +24,7 @@
  * THE SOFTWARE.
  */
 
+#define MICROPY_REPL_EMACS_WORDS_MOVE (1)
+#define MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE (1)
+
 #define MICROPY_PY_SYS_SETTRACE (1)
diff --git a/py/mpconfig.h b/py/mpconfig.h
index d6f4d9232..2c4169070 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -570,6 +570,21 @@
 #define MICROPY_REPL_EMACS_KEYS (0)
 #endif
 
+// Whether to include emacs-style word movement/kill readline behavior in REPL.
+// This adds Alt+F, Alt+B, Alt+D and Alt+Backspace for forward-word, backward-word, forward-kill-word
+// and backward-kill-word, respectively.
+#ifndef MICROPY_REPL_EMACS_WORDS_MOVE
+#define MICROPY_REPL_EMACS_WORDS_MOVE (0)
+#endif
+
+// Whether to include extra convenience keys for word movement/kill in readline REPL.
+// This adds Ctrl+Right, Ctrl+Left and Ctrl+W for forward-word, backward-word and backward-kill-word
+// respectively. Ctrl+Delete is not implemented because it's a very different escape sequence.
+// Depends on MICROPY_REPL_EMACS_WORDS_MOVE.
+#ifndef MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE
+#define MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE (0)
+#endif
+
 // Whether to implement auto-indent in REPL
 #ifndef MICROPY_REPL_AUTO_INDENT
 #define MICROPY_REPL_AUTO_INDENT (0)
diff --git a/tests/cmdline/repl_words_move.py b/tests/cmdline/repl_words_move.py
new file mode 100644
index 000000000..e1eb52953
--- /dev/null
+++ b/tests/cmdline/repl_words_move.py
@@ -0,0 +1,31 @@
+# word movement
+# backward-word, start in word
+234b1
+# backward-word, don't start in word
+234    b1
+# backward-word on start of line. if cursor is moved, this will result in a SyntaxError
+1 2 + 3
b+
+# forward-word, start in word
+1+2 12+f+3
+# forward-word, don't start in word
+1+    12 3
f+
+# forward-word on eol. if cursor is moved, this will result in a SyntaxError
+1 + 2 3f+
+
+# kill word
+# backward-kill-word, start in word
+100 + 45623
+# backward-kill-word, don't start in word
+100 + 456231
+# forward-kill-word, start in word
+100 + 256d3
+# forward-kill-word, don't start in word
+1 + 256d2
+
+# extra move/kill shortcuts
+# ctrl-left
+2341
+# ctrl-right
+123
+# ctrl-w
+1231
diff --git a/tests/cmdline/repl_words_move.py.exp b/tests/cmdline/repl_words_move.py.exp
new file mode 100644
index 000000000..86f6b7788
--- /dev/null
+++ b/tests/cmdline/repl_words_move.py.exp
@@ -0,0 +1,47 @@
+MicroPython \.\+ version
+Use \.\+
+>>> # word movement
+>>> # backward-word, start in word
+>>> \.\+
+1234
+>>> # backward-word, don't start in word
+>>> \.\+
+1234
+>>> # backward-word on start of line. if cursor is moved, this will result in a SyntaxError
+>>> \.\+
+6
+>>> # forward-word, start in word
+>>> \.\+
+18
+>>> # forward-word, don't start in word
+>>> \.\+
+16
+>>> # forward-word on eol. if cursor is moved, this will result in a SyntaxError
+>>> \.\+
+6
+>>> 
+>>> # kill word
+>>> # backward-kill-word, start in word
+>>> \.\+
+123
+>>> # backward-kill-word, don't start in word
+>>> \.\+
+101
+>>> # forward-kill-word, start in word
+>>> \.\+
+123
+>>> # forward-kill-word, don't start in word
+>>> \.\+
+3
+>>> 
+>>> # extra move/kill shortcuts
+>>> # ctrl-left
+>>> \.\+
+1234
+>>> # ctrl-right
+>>> \.\+
+123
+>>> # ctrl-w
+>>> \.\+
+1
+>>> 
diff --git a/tests/feature_check/repl_words_move_check.py b/tests/feature_check/repl_words_move_check.py
new file mode 100644
index 000000000..e74615e98
--- /dev/null
+++ b/tests/feature_check/repl_words_move_check.py
@@ -0,0 +1,4 @@
+# just check if ctrl+w is supported, because it makes sure that
+# both MICROPY_REPL_EMACS_WORDS_MOVE and MICROPY_REPL_EXTRA_WORDS_MOVE are enabled.
+t = 1231
+t == 1
diff --git a/tests/feature_check/repl_words_move_check.py.exp b/tests/feature_check/repl_words_move_check.py.exp
new file mode 100644
index 000000000..82a4e28ee
--- /dev/null
+++ b/tests/feature_check/repl_words_move_check.py.exp
@@ -0,0 +1,7 @@
+MicroPython \.\+ version
+Use \.\+
+>>> # Check for emacs keys in REPL
+>>> t = \.\+
+>>> t == 2
+True
+>>> 
diff --git a/tests/run-tests b/tests/run-tests
index b02463dc3..b8f5b6b7a 100755
--- a/tests/run-tests
+++ b/tests/run-tests
@@ -284,9 +284,14 @@ def run_tests(pyb, tests, args, base_path="."):
 
         # Check if emacs repl is supported, and skip such tests if it's not
         t = run_feature_check(pyb, args, base_path, 'repl_emacs_check.py')
-        if not 'True' in str(t, 'ascii'):
+        if 'True' not in str(t, 'ascii'):
             skip_tests.add('cmdline/repl_emacs_keys.py')
 
+        # Check if words movement in repl is supported, and skip such tests if it's not
+        t = run_feature_check(pyb, args, base_path, 'repl_words_move_check.py')
+        if 'True' not in str(t, 'ascii'):
+            skip_tests.add('cmdline/repl_words_move.py')
+
         upy_byteorder = run_feature_check(pyb, args, base_path, 'byteorder.py')
         upy_float_precision = run_feature_check(pyb, args, base_path, 'float.py')
         if upy_float_precision == b'CRASH':