Create parsing.py

parsing.py

@@ -0,0 +1,46 @@
+import re
+import typing as t
+
+BAD_CHARS_FOR_REGEX_REGEX = re.compile(r"[-\/\\^$*+?.()|[\]{}]")
+
+
+def _sanitize_string_for_use_in_a_regex(string: str) -> str:
+    '''Sanitizes `string` so it can be used inside of a regexp.'''
+    return BAD_CHARS_FOR_REGEX_REGEX.sub(r"\\\g<0>", string)
+
+
+def parse_messages_from_str(string: str, names: t.List[str]) -> t.List[str]:
+    '''
+    Given a big string containing raw chat history, this function attempts to
+    parse it out into a list where each item is an individual message.
+    '''
+    sanitized_names = [
+        _sanitize_string_for_use_in_a_regex(name) for name in names
+    ]
+
+    speaker_regex = re.compile(rf"^({'|'.join(sanitized_names)}): ?",
+                               re.MULTILINE)
+
+    message_start_indexes = []
+    for match in speaker_regex.finditer(string):
+        message_start_indexes.append(match.start())
+
+    # FIXME(11b): One of these returns is silently dropping the last message.
+    if len(message_start_indexes) < 2:
+        # Single message in the string.
+        return [string.strip()]
+
+    prev_start_idx = message_start_indexes[0]
+    messages = []
+
+    for start_idx in message_start_indexes[1:]:
+        message = string[prev_start_idx:start_idx].strip()
+        messages.append(message)
+        prev_start_idx = start_idx
+
+    return messages
+
+
+def serialize_chat_history(history: t.List[str]) -> str:
+    '''Given a structured chat history object, collapses it down to a string.'''
+    return "\n".join(history)