mermaid_diagram

Python package for generating the string which represents a Mermaid diagram.

It provides methods to build your diagram. The resulting diagram is returned as a string, either bare or enclosed within a Markdown code block. This package cannot produce image files of the diagrams.

Use cases:

• Include Mermaid diagrams (generated from data) in a markdown file which gets created using Python script.

Installation

You can install the package using pip:

pip install mermaid_diagram

Supported diagrams

This package supports the following Mermaid diagrams:

• Packet diagram (packet-beta).

Usage

Packet diagram

In this first example we build a diagram of the TCP packet, using the add_segment_bytes and add_segment_bits methods. To include the total packet size in the title, it uses the size_in_bytes and size_in_bits getters. Finally, the diagram string is returned as markdown code block.

from mermaid_diagram import Packet

d = Packet()
d.add_segment_bytes(2, "Source Port")
d.add_segment_bytes(2, "Destination Port")
d.add_segment_bytes(4, "Sequence Number")
d.add_segment_bytes(4, "Acknowledgment Number")
d.add_segment_bits(4, "Data Offset")
d.add_segment_bits(6, "Reserved")
d.add_segment_bits(1, "URG")
d.add_segment_bits(1, "ACK")
d.add_segment_bits(1, "PSH")
d.add_segment_bits(1, "RST")
d.add_segment_bits(1, "SYN")
d.add_segment_bits(1, "FIN")
d.add_segment_bytes(2, "Window")
d.add_segment_bytes(2, "Checksum")
d.add_segment_bytes(2, "Urgent Pointer")
d.add_segment_bytes(4, "(Options and Padding)")
d.add_segment_bytes(8, "Data (variable length)")
d.title = f"TCP Packet - {d.size_in_bytes} bytes ({d.size_in_bits} bits)"
print(d.diagram_markdown)

# ```mermaid
# ---
# title: "TCP Packet - 32 bytes (256 bits)"
# ---
# packet-beta
# 0-15 : "Source Port"
# 16-31 : "Destination Port"
# 32-63 : "Sequence Number"
# 64-95 : "Acknowledgment Number"
# 96-99 : "Data Offset"
# 100-105 : "Reserved"
# 106 : "URG"
# 107 : "ACK"
# 108 : "PSH"
# 109 : "RST"
# 110 : "SYN"
# 111 : "FIN"
# 112-127 : "Window"
# 128-143 : "Checksum"
# 144-159 : "Urgent Pointer"
# 160-191 : "(Options and Padding)"
# 192-255 : "Data (variable length)"
# ```

Which renders as:

In the next example we activate the use_number_prefix option, so that every segment gets a number prefix (e.g. 1) First segment). This can be helpful if the diagram will be accompanied by a numbered list where the segments are explained in detail.

from mermaid_diagram import Packet

d = Packet()
d.use_number_prefix = True
d.add_segment_bytes(2, "Source Port")
d.add_segment_bytes(2, "Destination Port")
d.add_segment_bytes(2, "Length")
d.add_segment_bytes(2, "Checksum")
d.add_segment_bytes(4, "Data (variable length)")
d.title = f"UDP Packet - {d.size_in_bytes} bytes ({d.size_in_bits} bits)"
print(d.diagram_markdown)

# ```mermaid
# ---
# title: "UDP Packet - 12 bytes (96 bits)"
# ---
# packet-beta
# 0-15 : "1) Source Port"
# 16-31 : "2) Destination Port"
# 32-47 : "3) Length"
# 48-63 : "4) Checksum"
# 64-95 : "5) Data (variable length)"
# ```

Which renders as:

Known issues

• No input validation or error handling.