Added prefix filtering to TagLine.tags() and Message.tags_from_file()

chatmastermind/message.py

@@ -219,9 +219,12 @@ class Message():
                    file_path=data.get(cls.file_yaml_key, None))
 
     @classmethod
-    def tags_from_file(cls: Type[MessageInst], file_path: pathlib.Path) -> set[Tag]:
+    def tags_from_file(cls: Type[MessageInst],
+                       file_path: pathlib.Path,
+                       prefix: Optional[str] = None) -> set[Tag]:
         """
-        Return only the tags from the given Message file.
+        Return only the tags from the given Message file,
+        optionally filtered based on prefix.
         """
         if not file_path.exists():
             raise MessageError(f"Message file '{file_path}' does not exist")
@@ -229,11 +232,14 @@ class Message():
             raise MessageError(f"File type '{file_path.suffix}' is not supported")
         if file_path.suffix == '.txt':
             with open(file_path, "r") as fd:
-                tags = TagLine(fd.readline()).tags()
+                tags = TagLine(fd.readline()).tags(prefix)
         else:  # '.yaml'
             with open(file_path, "r") as fd:
                 data = yaml.load(fd, Loader=yaml.FullLoader)
-                tags = set(sorted(data[cls.tags_yaml_key]))
+                if prefix and len(prefix) > 0:
+                    tags = set(sorted([t.strip() for t in data[cls.tags_yaml_key] if t.startswith(prefix)]))
+                else:
+                    tags = set(sorted(data[cls.tags_yaml_key]))
         return tags
 
     @classmethod

chatmastermind/tags.py

@@ -118,9 +118,10 @@ class TagLine(str):
         """
         return cls(' '.join([cls.prefix] + sorted([t for t in tags])))
 
-    def tags(self) -> set[Tag]:
+    def tags(self, prefix: Optional[str] = None) -> set[Tag]:
         """
-        Returns all tags contained in this line as a set.
+        Returns all tags contained in this line as a set, optionally
+        filtered based on prefix.
         """
         tagstr = self[len(self.prefix):].strip()
         separator = Tag.default_separator
@@ -130,7 +131,10 @@ class TagLine(str):
             if s in tagstr:
                 separator = s
                 break
-        return set(sorted([Tag(t.strip()) for t in tagstr.split(separator)]))
+        if prefix and len(prefix) > 0:
+            return set(sorted([Tag(t.strip()) for t in tagstr.split(separator) if t.startswith(prefix)]))
+        else:
+            return set(sorted([Tag(t.strip()) for t in tagstr.split(separator)]))
 
     def merge(self, taglines: set['TagLine']) -> 'TagLine':
         """