Allow `__getitem__` / `__setitem__`-like command access (#48)

* Allow using double quotes within triple double quotes.

* Add getitem / setitem-like command access.

* Add notes about possible `SyntaxError`s.

* Add comments describing how this works.

* Address style issues addressed by Aperture.

* Use single quotes, clarify comment.

* A little bit of whitespace by my line
a little bit of whitespace is all I need
a little readable code is what lemon sees
a little bit of it makes the code good, man

* Add several `trace` logs.

* Escape single quotes in the key.

* Fix a flake8 violation.

1 files changed, 56 insertions, 1 deletions

diff --git a/bot/__init__.py b/bot/__init__.py
index 76cab5a74..40c4eefdc 100644
--- a/bot/__init__.py
+++ b/bot/__init__.py
@@ -95,7 +95,7 @@ def _get_word(self) -> str:
     while not self.eof:
         try:
             current = self.buffer[self.index + pos]
-            if current.isspace() or current == "(":
+            if current.isspace() or current == "(" or current == "[":
                 break
             pos += 1
         except IndexError:
@@ -171,6 +171,61 @@ def _get_word(self) -> str:
         result = self.buffer[self.previous:self.index + (pos+2)]
         self.index += 2
 
+    # Check if a command in the form of `bot.tags['ask']`
+    # or alternatively `bot.tags['ask'] = 'whatever'` was used.
+    elif current == "[":
+        def clean_argument(arg: str) -> str:
+            """Helper function to remove any characters we don't care about."""
+
+            return arg.strip("[]'\" ").replace('"', '\\"')
+
+        log.trace(f"Got a command candidate for getitem / setitem mimick: {self.buffer}")
+        # Syntax is `bot.tags['ask']` => mimic `getattr`
+        if self.buffer.endswith("]"):
+            # Key: The first argument, specified `bot.tags[here]`
+            key = clean_argument(self.buffer[self.index:])
+            log.trace(f"Command mimicks getitem. Key: {key!r}")
+
+            # note: if not key, this corresponds to an empty argument
+            #       so this should throw / return a SyntaxError ?
+            args = f'"{key}"'
+
+            # Use the cog's `get` command.
+            result = self.buffer[self.previous:self.index] + ".get"
+
+        # Syntax is `bot.tags['ask'] = 'whatever'` => mimic `setattr`
+        elif "=" in self.buffer and not self.buffer.endswith("="):
+            equals_pos = self.buffer.find("=")
+
+            # Key: The first argument, specified `bot.tags[here]`
+            key = clean_argument(self.buffer[self.index:equals_pos])
+
+            # Value: The second argument, specified after the `=`
+            value = (
+                clean_argument(
+                    self.buffer.split("=")[1]
+                )
+                .replace("'", "\\'")  # escape any unescaped quotes
+            )
+            log.trace(f"Command mimicks setitem. Key: {key!r}, value: {value!r}.")
+
+            # Use the cog's `set` command.
+            result = self.buffer[self.previous:self.index] + ".set"
+            args = f'"{key}" "{value}"'
+
+        # Syntax is god knows what, pass it along
+        # in the future, this should probably return / throw SyntaxError
+        else:
+            result = self.buffer
+            args = ''
+            log.trace(f"Command is of unknown syntax: {self.buffer}")
+
+        # Reconstruct valid discord.py syntax
+        self.buffer = f"{result} {args}"
+        self.index = len(result)
+        self.end = len(self.buffer)
+        log.trace(f"Mimicked command: {self.buffer}")
+
     if isinstance(result, str):
         return result.lower()  # Case insensitivity, baby
     return result