Quick and dirty : converting from sequencediagram.org charts to mermaid

mermaidify.py

import re
from sys import stdin


def main():
    result = ""
    title_re = re.compile("^title (.*)$")
    right_arrow_re = re.compile(r"(.+?)\s*(-?)->\s*(.+?)(:(.+))?$")
    left_arrow_re = re.compile(r"(.+?)\s*<-(-?)\s*(.+?)(:(.+))?$")
    empty = re.compile("^\s*$")
    entryspacing = re.compile("^\s*entryspacing")
    group_re = re.compile("^group (.+)$")

    title = ""

    for line in stdin.readlines():
        if empty.match(line) or entryspacing.match(line):
            continue
        elif m := title_re.match(line):
            title = f"# {m.group(1)}"
            continue
        elif m := group_re.match(line):
            line = f"alt {m.group(1)}"
        elif m := right_arrow_re.match(line):
            line = f"{m.group(1)} {m.group(2)}->> {m.group(3)}: {m.group(5)}"
        elif m := left_arrow_re.match(line):
            line = f"{m.group(3)} {m.group(2)}->> {m.group(1)}: {m.group(5)}"

        line = line.replace(r"\n", "<br>")
        result = f"{result}\n{line}"

    print(f"""
{title}
```mermaid
sequenceDiagram
{result}
```
        """)


if __name__ == "__main__":
    main()