--  This source is licensed under the Sunset License v1.0


package Packrat.Errors is


    subtype Error_Message is String
        with Dynamic_Predicate => Valid_Message (Error_Message);

    type Error_Info is record
        Symbol   : Ada.Strings.Unbounded.Unbounded_String;
        Position : Natural;
    end record;

    type Error_Info_Array is array (Positive range <>) of Error_Info;


    --  Note: No consideration is given to ordering of Error_Info items
    --        encoded into an Error_Message string.

    --  Note: Using "&" to join two Valid Error_Messages together
    --        will result in an Error_Message that is also Valid,
    --        but for best results Join should be used instead to
    --        prevent duplication of Error_Info in the message.


    function Valid_Identifier
           (Check : in String)
        return Boolean;

    function Valid_Identifier
           (Check : in Ada.Strings.Unbounded.Unbounded_String)
        return Boolean;

    function Valid_Identifier_Array
           (Check : in Error_Info_Array)
        return Boolean;

    function Valid_Message
           (Check : in String)
        return Boolean;

    function Debug_String
           (This : in Error_Message)
        return String;


    function Join
           (Left, Right : in Error_Message)
        return Error_Message;


    function Encode
           (Name : in String;
            Pos  : in Natural)
        return Error_Message
    with Pre => Valid_Identifier (Name);

    function Encode
           (Name : in Ada.Strings.Unbounded.Unbounded_String;
            Pos  : in Natural)
        return Error_Message
    with Pre => Valid_Identifier (Name);

    function Encode
           (Info : in Error_Info)
        return Error_Message
    with Pre => Valid_Identifier (Info.Symbol);

    function Encode_Array
           (Info : in Error_Info_Array)
        return Error_Message
    with Pre => Valid_Identifier_Array (Info);

    function Decode
           (Msg : in Error_Message)
        return Error_Info_Array;


end Packrat.Errors;