py/repl: Skip private variables when printing tab completion options.

Any '_' variables/functions in frozen modules are currently printed, when
they shouldn't be.  That's due to underscore names possibly existing
between the start and end qstrs which are used to print the auto-complete
matches.  The underscore names should be skipped when iterating between the
two boundary qstrs.

The underscore attributes are removed from the extra coverage exp file
because tab completing "import <tab>" no longer lists modules beginning
with an underscore.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

5 files changed, 89 insertions, 10 deletions

diff --git a/py/repl.c b/py/repl.c
index 87c171cc8..b0ccfa383 100644
--- a/py/repl.c
+++ b/py/repl.c
@@ -218,6 +218,10 @@ static void print_completions(const mp_print_t *print,
     for (qstr q = q_first; q <= q_last; ++q) {
         size_t d_len;
         const char *d_str = (const char *)qstr_data(q, &d_len);
+        // filter out words that begin with underscore unless there's already a partial match
+        if (s_len == 0 && d_str[0] == '_') {
+            continue;
+        }
         if (s_len <= d_len && strncmp(s_start, d_str, s_len) == 0) {
             if (test_qstr(obj, q)) {
                 int gap = (line_len + WORD_SLOT_LEN - 1) / WORD_SLOT_LEN * WORD_SLOT_LEN - line_len;
diff --git a/pyproject.toml b/pyproject.toml
index 556dfdaee..0dd15d06c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,6 +29,7 @@ target-version = "py37"
 [tool.ruff.lint]
 exclude = [  # Ruff finds Python SyntaxError in these files
   "tests/cmdline/repl_autocomplete.py",
+  "tests/cmdline/repl_autocomplete_underscore.py",
   "tests/cmdline/repl_autoindent.py",
   "tests/cmdline/repl_basic.py",
   "tests/cmdline/repl_cont.py",
diff --git a/tests/cmdline/repl_autocomplete_underscore.py b/tests/cmdline/repl_autocomplete_underscore.py
new file mode 100644
index 000000000..98bbb6992
--- /dev/null
+++ b/tests/cmdline/repl_autocomplete_underscore.py
@@ -0,0 +1,33 @@
+# Test REPL autocompletion filtering of underscore attributes
+
+# Start paste mode
+{\x05}
+class TestClass:
+    def __init__(self):
+        self.public_attr = 1
+        self._private_attr = 2
+        self.__very_private = 3
+    
+    def public_method(self):
+        pass
+    
+    def _private_method(self):
+        pass
+    
+    @property
+    def public_property(self):
+        return 42
+    
+    @property  
+    def _private_property(self):
+        return 99
+
+{\x04}
+# Paste executed
+
+# Create an instance
+obj = TestClass()
+
+# Test tab completion on the instance
+# The tab character after `obj.` and 'a' below triggers the completions
+obj.{\x09}{\x09}a{\x09}
diff --git a/tests/cmdline/repl_autocomplete_underscore.py.exp b/tests/cmdline/repl_autocomplete_underscore.py.exp
new file mode 100644
index 000000000..35617554f
--- /dev/null
+++ b/tests/cmdline/repl_autocomplete_underscore.py.exp
@@ -0,0 +1,41 @@
+MicroPython \.\+ version
+Use Ctrl-D to exit, Ctrl-E for paste mode
+>>> # Test REPL autocompletion filtering of underscore attributes
+>>> 
+>>> # Start paste mode
+>>> 
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== 
+=== class TestClass:
+===     def __init__(self):
+===         self.public_attr = 1
+===         self._private_attr = 2
+===         self.__very_private = 3
+===     
+===     def public_method(self):
+===         pass
+===     
+===     def _private_method(self):
+===         pass
+===     
+===     @property
+===     def public_property(self):
+===         return 42
+===     
+===     @property  
+===     def _private_property(self):
+===         return 99
+=== 
+=== 
+>>> # Paste executed
+>>> 
+>>> # Create an instance
+>>> obj = TestClass()
+>>> 
+>>> # Test tab completion on the instance
+>>> # The tab character after `obj.` and 'a' below triggers the completions
+>>> obj.public_
+public_attr     public_method   public_property
+>>> obj.public_attr
+1
+>>> 
diff --git a/tests/ports/unix/extra_coverage.py.exp b/tests/ports/unix/extra_coverage.py.exp
index 3775036bb..ac64edde6 100644
--- a/tests/ports/unix/extra_coverage.py.exp
+++ b/tests/ports/unix/extra_coverage.py.exp
@@ -51,16 +51,16 @@ RuntimeError:
 ame__
 port 
 
-builtins        micropython     _asyncio        _thread
-array           binascii        btree           cexample
-cmath           collections     cppexample      cryptolib
-deflate         errno           example_package
-ffi             framebuf        gc              hashlib
-heapq           io              json            machine
-marshal         math            os              platform
-random          re              select          socket
-struct          sys             termios         time
-tls             uctypes         vfs             websocket
+builtins        micropython     array           binascii
+btree           cexample        cmath           collections
+cppexample      cryptolib       deflate         errno
+example_package                 ffi             framebuf
+gc              hashlib         heapq           io
+json            machine         marshal         math
+os              platform        random          re
+select          socket          struct          sys
+termios         time            tls             uctypes
+vfs             websocket
 me
 
 micropython     machine         marshal         math