Suggest known commands if there is no history

ChangeLog.md

@@ -22,6 +22,8 @@
   ([#24](https://github.com/davep/hike/pull/24))
 - Added `help` as a command that the command line understands.
   ([#24](https://github.com/davep/hike/pull/24))
+- Changed command line completion so that if history is empty, known
+  commands are suggested. ([#29](https://github.com/davep/hike/pull/29))
 
 ## v0.2.0
 

src/hike/widgets/command_line/base_command.py

@@ -54,23 +54,38 @@ def split_command(text: str) -> tuple[str, str]:
         return command.strip(), tail.strip()
 
     @classmethod
-    def is_command(cls, command: str) -> bool:
-        """Does the given command appear to be a match?
-
-        Args:
-            command: The command to test.
+    def suggestions(cls) -> tuple[str, ...]:
+        """The suggested command matches for this command.
 
         Returns:
-            `True` if the given command seems to be a match, `False` if not.
+            A tuple of suggestions for the command.
+
+        Notes:
+            Any commands that look like value placeholders will be filtered
+            out.
         """
         # Build up all the possible matches. These are built from the main
         # command and also the aliases. By convention the code will often
         # use `code` fences for commands, and the aliases will be a comma
         # list, so we clean that up as we go...
-        return command.strip().lower() in (
-            candidate.strip().lower().removeprefix("`").removesuffix("`")
+        return tuple(
+            candidate.strip().removeprefix("`").removesuffix("`")
             for candidate in (cls.COMMAND, *cls.ALIASES.split(","))
+            # Note that we filter out anything that looks like `<this>`.
+            if not candidate.startswith("`<")
         )
 
+    @classmethod
+    def is_command(cls, command: str) -> bool:
+        """Does the given command appear to be a match?
+
+        Args:
+            command: The command to test.
+
+        Returns:
+            `True` if the given command seems to be a match, `False` if not.
+        """
+        return command.strip().lower() in cls.suggestions()
+
 
 ### base_command.py ends here

src/hike/widgets/command_line/widget.py

@@ -7,6 +7,7 @@
 ##############################################################################
 # Python imports.
 from dataclasses import dataclass
+from itertools import chain
 from typing import Final
 
 ##############################################################################
@@ -149,8 +150,16 @@ class CommandLine(Vertical):
 
     @property
     def _history_suggester(self) -> SuggestFromList:
-        """A suggester for the history of input."""
-        return SuggestFromList(reversed(list(self.history)))
+        """A suggester for the history of input.
+
+        If there us no history yet then a list of commands and aliases will
+        be used.
+        """
+        return SuggestFromList(
+            reversed(list(self.history))
+            if self.history
+            else chain(*(command.suggestions() for command in COMMANDS))
+        )
 
     def compose(self) -> ComposeResult:
         """Compose the content of the widget."""