mermoid · v0.2.0

Class diagrams

classDiagram draws types and the relations between them. A class is a stack of bands: the name, the attributes, and the operations. An empty band stays visible unless the diagram says hideEmptyMembersBox.

MermoidAscent.svgDiagram(Mermaid("""classDiagram
    class BankAccount {
        +String owner
        +BigDecimal balance
        +deposit(amount) bool
        +withdrawal(amount) int
    }
""".stripMargin))
BankAccount+String owner+BigDecimal balance+deposit(amount) bool+withdrawal(amount) int

Members

() is what makes a member an operation. Anything else is an attribute. + - # ~ are public, private, protected, and package. A trailing * is abstract and a trailing $ is static. List~Int~ is a generic, on the class or on a member. Name : member adds one member to a class that already exists.

MermoidAscent.svgDiagram(Mermaid("""classDiagram
    class Square~Shape~ {
        +int id
        +List~Int~ points
        +getPoints() List~Int~
    }
""".stripMargin))
Square~Shape~+int id+List~Int~ points+getPoints() List~Int~

Relations

The head is the UML glyph, not a flowchart arrow. <|-- is inheritance, *-- composition, o-- aggregation, --> association, ..> dependency, ..|> realization, -- a solid link, .. a dashed link. A quoted cardinality sits beside the end it describes. ()-- is a lollipop interface.

MermoidAscent.svgDiagram(Mermaid("""classDiagram
    class Customer
    class Order
    class LineItem
    Customer "1" --> "*" Order : places
    Order "1" *-- "*" LineItem : contains
""".stripMargin))
1 places *1 contains *CustomerOrderLineItem

Stereotypes and namespaces

<<interface>>, <<abstract>>, <<enumeration>>, and <<service>> are the usual annotations. Any other <<name>> is kept as written. Two different stereotypes on one class is a parse error that names both.

namespace Id { ... } is a frame. A direction inside the diagram applies to every namespace as well as the page. A class named in two namespaces is a parse error that names both.

MermoidAscent.svgDiagram(Mermaid("""classDiagram
    direction LR
    namespace Billing {
        class Invoice
        class Payment
        Invoice --> Payment : settled by
    }
    class Customer
    Customer --> Invoice : receives
""".stripMargin))
Billingreceivessettled byCustomerInvoicePayment