Merge branch 'pr/325'

fbchat/models.py

@@ -2,6 +2,7 @@
 
 from __future__ import unicode_literals
 import aenum
+from string import Formatter
 
 
 class FBchatException(Exception):
@@ -219,6 +220,52 @@ class Message(object):
     def __unicode__(self):
         return '<Message ({}): {}, mentions={} emoji_size={} attachments={}>'.format(self.uid, repr(self.text), self.mentions, self.emoji_size, self.attachments)
 
+    @classmethod
+    def formatMentions(cls, text, *args, **kwargs):
+        """Like `str.format`, but takes tuples with a thread id and text instead.
+
+        Returns a `Message` object, with the formatted string and relevant mentions.
+
+        ```
+        >>> Message.formatMentions("Hey {!r}! My name is {}", ("1234", "Peter"), ("4321", "Michael"))
+        <Message (None): "Hey 'Peter'! My name is Michael", mentions=[<Mention 1234: offset=4 length=7>, <Mention 4321: offset=24 length=7>] emoji_size=None attachments=[]>
+
+        >>> Message.formatMentions("Hey {p}! My name is {}", ("1234", "Michael"), p=("4321", "Peter"))
+        <Message (None): 'Hey Peter! My name is Michael', mentions=[<Mention 4321: offset=4 length=5>, <Mention 1234: offset=22 length=7>] emoji_size=None attachments=[]>
+        ```
+        """
+        result = ""
+        mentions = list()
+        offset = 0
+        f = Formatter()
+        field_names = [field_name[1] for field_name in f.parse(text)]
+        automatic = '' in field_names
+        i = 0
+
+        for (literal_text, field_name, format_spec, conversion) in f.parse(text):
+            offset += len(literal_text)
+            result += literal_text
+
+            if field_name is None: continue
+
+            if field_name == '':
+                field_name = str(i)
+                i += 1
+            elif automatic and field_name.isdigit():
+                raise ValueError("cannot switch from automatic field numbering to manual field specification")
+
+            thread_id, name = f.get_field(field_name, args, kwargs)[0]
+
+            if format_spec: name = f.format_field(name, format_spec)
+            if conversion: name = f.convert_field(name, conversion)
+
+            result += name
+            mentions.append(Mention(thread_id=thread_id, offset=offset, length=len(name)))
+            offset += len(name)
+
+        message = cls(text=result, mentions=mentions)
+        return message
+
 class Attachment(object):
     #: The attachment ID
     uid = None