with

    Ada.Unchecked_Deallocation;


package body Packrat.Lexer is


    procedure Free_Array is new Ada.Unchecked_Deallocation
        (Object => Element_Array, Name => Element_Array_Access);


    procedure Initialize
           (This : in out Combinator_Result) is
    begin
        null;
    end Initialize;


    procedure Adjust
           (This : in out Combinator_Result) is
    begin
        if This.Value /= null then
            declare
                New_Array : Element_Array_Access :=
                    new Element_Array (1 .. This.Value.all'Length);
            begin
                New_Array.all := This.Value.all;
                This.Value := New_Array;
            end;
        end if;
    end Adjust;


    procedure Finalize
           (This : in out Combinator_Result) is
    begin
        if This.Value /= null then
            Free_Array (This.Value);
        end if;
    end Finalize;





    function Create_Result
           (Length : in Natural;
            Status : in Result_Status;
            Value  : in Element_Array)
        return Combinator_Result
    is
        This : Combinator_Result;
    begin
        This.Length := Length;
        This.Status := Status;
        This.Value := new Element_Array (1 .. Value'Length);
        This.Value.all := Value;
        return This;
    end Create_Result;


    function Join
           (Left, Right : in Combinator_Result)
        return Combinator_Result
    is
        Merge : Combinator_Result;
        Left_Valsize, Right_Valsize, Total_Valsize : Natural;
    begin
        if Left.Value /= null then
            Left_Valsize := Left.Value.all'Length;
        else
            Left_Valsize := 0;
        end if;
        if Right.Value /= null then
            Right_Valsize := Right.Value.all'Length;
        else
            Right_Valsize := 0;
        end if;
        Total_Valsize := Left_Valsize + Right_Valsize;

        if Left.Status = Success then
            Merge.Length := Left.Length + Right.Length;
            Merge.Status := Right.Status;
            if Total_Valsize /= 0 or Right.Status /= Failure then
                Merge.Value := new Element_Array (1 .. Total_Valsize);
                if Left_Valsize /= 0 then
                    Merge.Value.all (1 .. Left_Valsize) := Left.Value.all;
                end if;
                if Right_Valsize /= 0 then
                    Merge.Value.all (Left_Valsize + 1 .. Total_Valsize) := Right.Value.all;
                end if;
            end if;
            return Merge;
        else
            return Left;
        end if;
    end Join;


    function "="
           (Left, Right : in Combinator_Result)
        return Boolean
    is
        Null_Check : Boolean :=
            Left.Value = null and Right.Value = null;
        Value_Check : Boolean :=
            Left.Value /= null and then Right.Value /= null and then
            Left.Value.all = Right.Value.all;
    begin
        return Left.Length = Right.Length and
            Left.Status = Right.Status and
            (Null_Check or Value_Check);
    end "=";


    function Status
           (This : in Combinator_Result)
        return Result_Status is
    begin
        return This.Status;
    end Status;


end Packrat.Lexer;