grammar.md

Canfig Grammar

The Canfig language uses three main keywords to define and manage configurations:

• STRUCT: This tag is used to define a new data type or structure. For example, creating a time structure to ensure time-related configurations are consistently handled.

  STRUCT TIME(max_minute: int = 1000) {
      minute INT,
      second INT,
      CONSTRAINT CHK_Time CHECK (second >= 18 AND minute < max_minute)
  };
  

• CONFIG: This keyword defines a configuration entry. Each CONFIG is an instance of a STRUCT or built-in type that specifies how a particular setting or feature should be configured.

nested config structure will be implemented in the future

CONFIG Server: {
    run             BOOLEAN DEFAULT 1,
    name            NAME,
    port            INT,
    description     TEXT    DEFAULT 'default description',
    commands        LIST(COMMAND), 
    alive_time      TIME
};

• TRIGGER: similar to trigger for database, but use Python code to define trigger

TRIGGER ServerChangeAction WHEN CHANGE Server {
    # python interpreter integration
    if err_msg := ASSERT_UNQIUE(list=Server.commands, 
                                getter=lambda obj: obj['name']):
        return CANFIG_ERR(msg=err_msg)
};

• SLICE: Similar to a view (VIEW) in SQL, this keyword allows the definition of slices using set operators. Slices are dynamic selections of data from one or more configurations that behave as virtual configurations. They are particularly useful for creating customized views or subsets of configurations based on specific criteria.

NOT IMPLEMENTED YET!

SLICE Default       = {};
SLICE UserConfig    = (Runner - {Runner.commands}) + {Server.name, Server.port, Server.description};

Complete sample can be find in: sample.cand

By following these steps and utilizing the Canfig language keywords, developers can efficiently define, manage, and utilize complex configurations within their applications.