1 files changed, 88 insertions, 0 deletions
diff --git a/telepot/text.py b/telepot/text.py
new file mode 100644
index 0000000..d4b3cb7
--- /dev/null
+++ b/telepot/text.py
@@ -0,0 +1,88 @@
+def _apply_entities(text, entities, escape_map, format_map):
+    def inside_entities(i):
+        return any(map(lambda e:
+                           e['offset'] <= i < e['offset']+e['length'],
+                       entities))
+
+    # Split string into char sequence and escape in-place to
+    # preserve index positions.
+    seq = list(map(lambda c,i:
+                       escape_map[c]     # escape special characters
+                           if c in escape_map and not inside_entities(i)
+                       else c,
+                   list(text),           # split string to char sequence
+                   range(0,len(text))))  # along with each char's index
+
+    # Ensure smaller offsets come first
+    sorted_entities = sorted(entities, key=lambda e: e['offset'])
+    offset = 0
+    result = ''
+
+    for e in sorted_entities:
+        f,n,t = e['offset'], e['length'], e['type']
+
+        result += ''.join(seq[offset:f])
+
+        if t in format_map:
+            # apply format
+            result += format_map[t](''.join(seq[f:f+n]), e)
+        else:
+            result += ''.join(seq[f:f+n])
+
+        offset = f + n
+
+    result += ''.join(seq[offset:])
+    return result
+
+
+def apply_entities_as_markdown(text, entities):
+    """
+    Format text as Markdown. Also take care of escaping special characters.
+    Returned value can be passed to :meth:`.Bot.sendMessage` with appropriate
+    ``parse_mode``.
+
+    :param text:
+        plain text
+
+    :param entities:
+        a list of `MessageEntity <https://core.telegram.org/bots/api#messageentity>`_ objects
+    """
+    escapes = {'*': '\\*',
+               '_': '\\_',
+               '[': '\\[',
+               '`': '\\`',}
+
+    formatters = {'bold':         lambda s,e: '*'+s+'*',
+                  'italic':       lambda s,e: '_'+s+'_',
+                  'text_link':    lambda s,e: '['+s+']('+e['url']+')',
+                  'text_mention': lambda s,e: '['+s+'](tg://user?id='+str(e['user']['id'])+')',
+                  'code':         lambda s,e: '`'+s+'`',
+                  'pre':          lambda s,e: '```text\n'+s+'```'}
+
+    return _apply_entities(text, entities, escapes, formatters)
+
+
+def apply_entities_as_html(text, entities):
+    """
+    Format text as HTML. Also take care of escaping special characters.
+    Returned value can be passed to :meth:`.Bot.sendMessage` with appropriate
+    ``parse_mode``.
+
+    :param text:
+        plain text
+
+    :param entities:
+        a list of `MessageEntity <https://core.telegram.org/bots/api#messageentity>`_ objects
+    """
+    escapes = {'<': '&lt;',
+               '>': '&gt;',
+               '&': '&amp;',}
+
+    formatters = {'bold':         lambda s,e: '<b>'+s+'</b>',
+                  'italic':       lambda s,e: '<i>'+s+'</i>',
+                  'text_link':    lambda s,e: '<a href="'+e['url']+'">'+s+'</a>',
+                  'text_mention': lambda s,e: '<a href="tg://user?id='+str(e['user']['id'])+'">'+s+'</a>',
+                  'code':         lambda s,e: '<code>'+s+'</code>',
+                  'pre':          lambda s,e: '<pre>'+s+'</pre>'}
+
+    return _apply_entities(text, entities, escapes, formatters)