RFC: Support emoji in messages and participant names

[MrCoder]

Context

Emojis are considered characters on the web and in digital text. They are encoded as part of the Unicode standard. In Unicode, emojis have their own code points, just like letters, numbers, and special characters. For example, the emoji 😊 has the Unicode code point U+1F60A.

When you include an emoji in a text message, email, tweet, or any other form of digital text, it is treated as a single character, even though it may visually appear more complex than a letter or number. However, it’s worth noting that some emojis are made up of multiple Unicode code points, such as emojis that combine a base emoji with a skin tone modifier.

The syntax :unicorn: (🦄) is a type of shortcode used by certain platforms and applications to represent emojis. This particular syntax, where an emoji is represented by a short string of text enclosed in colons, is commonly used in Slack, GitHub, Discourse, and some other communication and collaboration tools.

Syntax in ZenUML

To support ZenUML, we will add emoji support to the following areas:

1. Participant Name
2. Message including parameters
3. Conditions for Alt and Loop fragment
4. Divider notes
5. Comments

Syntax must support two ways of embedding emojis: 1. use the emoji directly; 2. use shortcut.

Participant Name

Participant declaration

:unicorn:OrderService

Considerations

The main challenge in implementing this is to resolve ambiguity between an emoji and an async message which also use :.

An async message is like: A->B:async message. An emoji can be used like :unicorn:A->:butterfly:B: :cry: some more messages.