Q -- Abstract Syntax Tree

ast.rb

[
    :system,
    [
        :type_def,
        "Boolean",
        [
            :union_type,
            [
                :builtin_type,
                "TrueClass"
            ],
            [
                :builtin_type,
                "FalseClass"
            ]
        ]
    ],
    [
        :type_def,
        "String",
        [
            :builtin_type,
            "String"
        ]
    ],
    [
        :type_def,
        "Real",
        [
            :builtin_type,
            "Float"
        ]
    ],
    [
        :type_def,
        "Integer",
        [
            :builtin_type,
            "Fixnum"
        ]
    ],
    [
        :type_def,
        "Date",
        [
            :ad_type,
            "Date",
            [
                :contract,
                "iso8601",
                [
                    :builtin_type,
                    "String"
                ],
                [
                    :inline_pair,
                    [
                        :fn,
                        [
                            :parameters,
                            "s"
                        ],
                        [
                            :source,
                            "Date.iso8601(s)"
                        ]
                    ],
                    [
                        :fn,
                        [
                            :parameters,
                            "t"
                        ],
                        [
                            :source,
                            "t.iso8601"
                        ]
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Time",
        [
            :ad_type,
            "Time",
            [
                :contract,
                "iso8601",
                [
                    :builtin_type,
                    "String"
                ],
                [
                    :inline_pair,
                    [
                        :fn,
                        [
                            :parameters,
                            "s"
                        ],
                        [
                            :source,
                            "DateTime.parse(s)"
                        ]
                    ],
                    [
                        :fn,
                        [
                            :parameters,
                            "t"
                        ],
                        [
                            :source,
                            "t.iso8601"
                        ]
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Uuid",
        [
            :sub_type,
            [
                :type_ref,
                "String"
            ],
            [
                :constraint,
                "default",
                [
                    :fn,
                    [
                        :parameters,
                        "s"
                    ],
                    [
                        :source,
                        "s.size == 36"
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Dose",
        [
            :ad_type,
            nil,
            [
                :contract,
                "as",
                [
                    :sub_type,
                    [
                        :type_ref,
                        "Real"
                    ],
                    [
                        :constraint,
                        "default",
                        [
                            :fn,
                            [
                                :parameters,
                                "f"
                            ],
                            [
                                :source,
                                "f >= 0.0 and f <= 1.0"
                            ]
                        ]
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Gender",
        [
            :ad_type,
            nil,
            [
                :contract,
                "as",
                [
                    :sub_type,
                    [
                        :type_ref,
                        "String"
                    ],
                    [
                        :constraint,
                        "default",
                        [
                            :fn,
                            [
                                :parameters,
                                "s"
                            ],
                            [
                                :source,
                                "s == 'M' or s == 'F'"
                            ]
                        ]
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Duration",
        [
            :ad_type,
            nil,
            [
                :contract,
                "minutes",
                [
                    :sub_type,
                    [
                        :type_ref,
                        "Integer"
                    ],
                    [
                        :constraint,
                        "default",
                        [
                            :fn,
                            [
                                :parameters,
                                "i"
                            ],
                            [
                                :source,
                                "i > 0"
                            ]
                        ]
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Name",
        [
            :sub_type,
            [
                :type_ref,
                "String"
            ],
            [
                :constraint,
                "default",
                [
                    :fn,
                    [
                        :parameters,
                        "s"
                    ],
                    [
                        :source,
                        "s.strip.size > 0"
                    ]
                ]
            ]
        ]
    ],
    [
        :type_def,
        "Appointment",
        [
            :tuple_type,
            [
                :heading,
                [
                    :attribute,
                    "at",
                    [
                        :type_ref,
                        "Time"
                    ]
                ],
                [
                    :attribute,
                    "duration",
                    [
                        :type_ref,
                        "Duration"
                    ]
                ],
                [
                    :attribute,
                    "fixed",
                    [
                        :type_ref,
                        "Boolean"
                    ]
                ]
            ]
        ]
    ],
    [
        :relation_type,
        [
            :heading,
            [
                :attribute,
                "id",
                [
                    :type_ref,
                    "Uuid"
                ]
            ],
            [
                :attribute,
                "diagnosis_date",
                [
                    :type_ref,
                    "Date"
                ]
            ],
            [
                :attribute,
                "patient",
                [
                    :tuple_type,
                    [
                        :heading,
                        [
                            :attribute,
                            "id",
                            [
                                :type_ref,
                                "Uuid"
                            ]
                        ],
                        [
                            :attribute,
                            "name",
                            [
                                :type_ref,
                                "Name"
                            ]
                        ],
                        [
                            :attribute,
                            "gender",
                            [
                                :type_ref,
                                "Gender"
                            ]
                        ]
                    ]
                ]
            ],
            [
                :attribute,
                "appointments",
                [
                    :set_type,
                    [
                        :type_ref,
                        "Appointment"
                    ]
                ]
            ]
        ]
    ]
]

how.rb

require 'qrb'
require 'awesome_print'

ap Qrb.ast(File.read('schema.q')), index: false

schema.q

# Mapping with the host language (can be provided by Qrb itself)
Boolean = .TrueClass|.FalseClass
String  = .String
Real    = .Float
Integer = .Fixnum
Date    = .Date <iso8601> .String \( s | Date.iso8601(s)   )
                                  \( t | t.iso8601         )
Time    = .Time <iso8601> .String \( s | DateTime.parse(s) )
                                  \( t | t.iso8601         )

# Some reusable data types (could be reused across schemas)
Uuid        = String( s | s.size == 36 )
Dose        = <as> Real( f |  f >= 0.0 and f <= 1.0 )
Gender      = <as> String( s | s == 'M' or s == 'F' )
Duration    = <minutes> Integer( i | i > 0 )
Name        = String( s | s.strip.size > 0 )
Appointment = {
  at: Time,
  duration: Duration,
  fixed: Boolean
}

# The main schema, for instance for a RESTful resource or a NoSQL
# database
{{
  id: Uuid,
  diagnosis_date: Date,
  patient: {
    id: Uuid,
    name: Name,
    gender: Gender
  },
  appointments: {Appointment}
}}