cli.lwp3.repl: add basic code completion

Author: dlech

CHANGELOG.md

@@ -91,6 +91,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Size check when restoring firmware via USB/DFU.
 - Added `pybricksdev.tools.chunk()` function.
+- Added basic command completion to `pybricksdev lwp3 repl`.
 ### Fixed
 - Wait for some time to allow program output to be received before disconnecting
   in the `run` command.

pybricksdev/cli/lwp3/repl.py

@@ -7,9 +7,11 @@
 """
 
 import asyncio
+from enum import Enum
 import inspect
 import logging
 import os
+import re
 import struct
 from pathlib import Path
 
@@ -18,6 +20,8 @@
 from bleak.backends.device import BLEDevice
 from bleak.backends.scanner import AdvertisementData
 from prompt_toolkit import PromptSession
+from prompt_toolkit.completion import Completer, Completion, FuzzyCompleter
+from prompt_toolkit.document import Document
 from prompt_toolkit.history import FileHistory
 from prompt_toolkit.patch_stdout import StdoutProxy, patch_stdout
 
@@ -42,34 +46,65 @@
 
 # The first groups is any type from bytecodes that inherits from int (includes
 # enums/flags) or bytes.
-_eval_pool.update(
-    {
-        k: v
-        for k, v in bytecodes.__dict__.items()
-        if inspect.isclass(v)
-        and v.__module__ == bytecodes.__name__
-        and (issubclass(v, int) or issubclass(v, bytes))
-    }
-)
+_PARAMETER_TYPES = {
+    k: v
+    for k, v in bytecodes.__dict__.items()
+    if inspect.isclass(v)
+    and v.__module__ == bytecodes.__name__
+    and (issubclass(v, int) or issubclass(v, bytes))
+}
+
+_eval_pool.update(_PARAMETER_TYPES)
 
 # The second group are all of the non-abstract message types from the messages module.
-_eval_pool.update(
-    {
-        k: v
-        for k, v in messages.__dict__.items()
-        if inspect.isclass(v)
-        and issubclass(v, AbstractMessage)
-        and not inspect.isabstract(v)
-    }
-)
+_MESSAGE_KINDS = {
+    k: v
+    for k, v in messages.__dict__.items()
+    if inspect.isclass(v)
+    and issubclass(v, AbstractMessage)
+    and not inspect.isabstract(v)
+}
+
+_eval_pool.update(_MESSAGE_KINDS)
+
+
+class _CommandCompleter(Completer):
+    """
+    Custom completer for command prompt.
+    """
+
+    # matches words with dots in them, e.g. "Enum.MEMBER"
+    _MATCH_DOT = re.compile(r"[a-zA-Z0-9_\.]+")
+
+    def get_completions(self, document: Document, complete_event):
+        if document.get_word_before_cursor() == ".":
+            # if this is a dotted word, look up the enum member
+            cls = _PARAMETER_TYPES.get(
+                document.get_word_before_cursor(pattern=self._MATCH_DOT).split(".")[0]
+            )
+            if cls and issubclass(cls, Enum):
+                for m in cls:
+                    yield Completion(m.name)
+        elif document.find_enclosing_bracket_left("(", ")") is not None:
+            # if we are inside of "(...)", list the enums and other parameter types
+            for p in _PARAMETER_TYPES.keys():
+                yield Completion(p)
+        elif document.get_word_under_cursor() == "":
+            # if we are at the beginning of the line, list the commands
+            for m in _MESSAGE_KINDS.keys():
+                yield Completion(m)
 
 
 async def repl() -> None:
     """
     Provides an interactive REPL for sending and receiving LWP3 messages.
     """
     os.makedirs(history_file.parent, exist_ok=True)
-    session = PromptSession(history=FileHistory(history_file))
+
+    session = PromptSession(
+        history=FileHistory(history_file),
+        completer=FuzzyCompleter(_CommandCompleter()),
+    )
 
     def match_lwp3_uuid(dev: BLEDevice, adv: AdvertisementData) -> None:
         if LWP3_HUB_SERVICE_UUID.lower() not in adv.service_uuids: