335 lines
11 KiB
Ada
335 lines
11 KiB
Ada
with Ada.Unchecked_Deallocation;
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package body H3.Strings is
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BUFFER_ALIGN: constant := 16;
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type Shift_Direction is (SHIFT_LEFT, SHIFT_RIGHT);
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function To_Character_Array (Str: in Elastic_String) return Character_Array is
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begin
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return Str.Buffer.Slot(Str.Buffer.Slot'First .. Str.Buffer.Last);
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end To_Character_Array;
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-- return the buffer capacity excluding the terminator
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function Get_Capacity (Str: in Elastic_String) return System_Size is
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begin
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return Str.Buffer.Slot'Length - 1;
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end Get_Capacity;
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-- private. return the buffer capacity including the terminator
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function Get_Hard_Capacity (Str: in Elastic_String) return System_Size is
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begin
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return Str.Buffer.Slot'Length;
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end Get_Hard_Capacity;
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pragma Inline (Get_Hard_Capacity);
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function Get_Length (Str: in Elastic_String) return System_Size is
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begin
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return 1 + Str.Buffer.Last - Str.Buffer.Slot'First;
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end Get_Length;
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function Get_First_Index (Str: in Elastic_String) return System_Size is
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begin
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return Str.Buffer.Slot'First;
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end Get_First_Index;
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function Get_Last_Index (Str: in Elastic_String) return System_Size is
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begin
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return Str.Buffer.Last;
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end Get_Last_Index;
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function Get_Item (Str: in Elastic_String; Pos: in System_Index) return Character_Type is
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begin
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return Str.Buffer.Slot(Pos);
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end Get_Item;
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-- unsafe as it exposes the internal buffer which can go away.
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-- assume the system address is equal to the thin pointer in size.
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function Get_Slot_Pointer (Str: in Elastic_String) return Thin_Character_Array_Pointer is
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A: System.Address := Str.Buffer.Slot(Str.Buffer.Slot'First)'Address;
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P: Thin_Character_Array_Pointer;
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for P'Address use A'Address;
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pragma Import (Ada, P);
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begin
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return P;
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end Get_Slot_Pointer;
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function Is_Shared(Str: in Elastic_String) return Standard.Boolean is
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begin
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return Str.Buffer /= Empty_Buffer'Access and then Str.Buffer.Refs > 1;
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end Is_Shared;
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procedure Free_Buffer (Str: in out Elastic_String) is
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begin
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if Str.Buffer /= Empty_Buffer'Access then
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declare
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procedure Free is new Ada.Unchecked_Deallocation(Buffer_Record, Buffer_Pointer);
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begin
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Free (Str.Buffer);
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end;
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end if;
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end Free_Buffer;
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procedure Ref_Buffer (Buf: in out Buffer_Pointer) is
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begin
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if Buf /= Empty_Buffer'Access then
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Buf.Refs := Buf.Refs + 1;
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end if;
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end Ref_Buffer;
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procedure Unref_Buffer (Buf: in out Buffer_Pointer) is
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begin
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if Buf /= Empty_Buffer'Access then
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if Buf.Refs = 1 then
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declare
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procedure Free is new Ada.Unchecked_Deallocation(Buffer_Record, Buffer_Pointer);
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begin
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Free (Buf);
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end;
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Buf := Empty_Buffer'Access;
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else
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Buf.Refs := Buf.Refs - 1;
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end if;
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end if;
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end Unref_Buffer;
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function New_Buffer_Container (Hard_Capa: in System_Size) return Elastic_String is
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Tmp: Elastic_String;
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begin
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Tmp.Buffer := new Buffer_Record(Hard_Capa);
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Tmp.Buffer.Refs := 1;
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return Tmp;
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end New_Buffer_Container;
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-- prepare the buffer for writing
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procedure Prepare_Buffer (Str: in out Elastic_String) is
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Tmp: Elastic_String;
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begin
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if Str.Buffer /= Empty_Buffer'Access then
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if Is_Shared(Str) then
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-- The code like this doesn't work correctly in terms of finalization.
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-- The buffer pointer held inside a finalization controlled record must be
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-- manipluated through the record itself. otherwise, the Adjust and Finalize
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-- calls goes incompatible with the reference counting implementation.
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-- It is because finalization is set on the record rather than the buffer pointer.
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--Tmp: Buffer_Pointer;
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--Tmp := new Buffer_Record(Get_Hard_Capacity(Str));
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--Tmp.Slot := Str.Buffer.Slot;
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--Tmp.Last := Str.Buffer.Last;
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--Tmp.Refs := 1;
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--Unref_Buffer (Str.Buffer);
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--Str.Buffer := Tmp;
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Tmp := Str;
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Str := New_Buffer_Container(Get_Hard_Capacity(Str));
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Str.Buffer.Slot := Tmp.Buffer.Slot;
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Str.Buffer.Last := Tmp.Buffer.Last;
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end if;
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end if;
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end Prepare_Buffer;
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-- prepare the buffer for writing
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procedure Prepare_Buffer (Str: in out Elastic_String; Req_Hard_Capa: in System_Size; Shift_Pos: in System_Size := 0; Shift_Size: in System_Size := 0; Shift_Dir: in Shift_Direction := Shift_Right) is
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Tmp: Elastic_String;
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First, Last: System_Size;
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Hard_Capa: System_Size;
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begin
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First := Get_First_Index(Str);
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Last := Get_Last_Index(Str);
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if Str.Buffer /= Empty_Buffer'Access and then Is_Shared(Str) then
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if Req_Hard_Capa < Get_Hard_Capacity(Str) then
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Hard_Capa := Get_Hard_Capacity(Str);
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else
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Hard_Capa := Req_Hard_Capa;
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end if;
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Tmp := Str;
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Str := New_Buffer_Container(Hard_Capa);
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goto COPY_OVER;
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else
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if Req_Hard_Capa > Get_Hard_Capacity(Str) then
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Tmp := Str;
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Str := New_Buffer_Container(Req_Hard_Capa);
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goto COPY_OVER;
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elsif Shift_Pos > 0 then
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Tmp := Str;
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goto COPY_OVER_WITH_SHIFT;
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else
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-- no shift, no change in the buffer
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null;
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end if;
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end if;
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return;
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<<COPY_OVER>>
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if Shift_Pos <= 0 then
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-- no shift is required. copy the entire string including th
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Str.Buffer.Slot(First .. Last + 1) := Tmp.Buffer.Slot(First .. Last + 1);
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Str.Buffer.Last := Last;
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return;
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end if;
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<<COPY_OVER_WITH_SHIFT>>
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-- it is an internal function. perform no sanity check.
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-- if Shift_Pos or Shift_Size is beyond the allocated capacity,
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-- it will end up in an exception.
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if Shift_Dir = SHIFT_LEFT then
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declare
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Mid: System_Size := Shift_Pos - Shift_Size;
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begin
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Str.Buffer.Slot(First .. Mid) := Tmp.Buffer.Slot(First .. Mid);
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Str.Buffer.Slot(Mid + 1 .. Last - Shift_Size + 1) := Tmp.Buffer.Slot(Shift_Pos + 1 .. Last + 1);
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Str.Buffer.Last := Last - Shift_Size;
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end;
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else
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Str.Buffer.Slot(First .. Shift_Pos - 1) := Tmp.Buffer.Slot(First .. Shift_Pos - 1);
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Str.Buffer.Slot(Shift_Pos + Shift_Size .. Last + Shift_Size + 1) := Tmp.Buffer.Slot(Shift_Pos .. Last + 1);
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Str.Buffer.Last := Last + Shift_Size;
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end if;
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end Prepare_Buffer;
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procedure Clear (Str: in out Elastic_String) is
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begin
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Prepare_Buffer (Str);
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Str.Buffer.Last := Get_First_Index(Str) - 1;
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end Clear;
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procedure Purge (Str: in out Elastic_String) is
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begin
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Unref_Buffer (Str.Buffer);
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Str.Buffer := Empty_Buffer'Access;
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end Purge;
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procedure Insert (Str: in out Elastic_String; Pos: in System_Index; V: in Character_Type; Repeat: in System_Size := 1) is
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Act_Pos: System_Index := Pos;
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Act_Inc: System_Size := Repeat;
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begin
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if Act_Pos > Str.Buffer.Last then
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Act_Pos := Str.Buffer.Last + 1;
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end if;
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Prepare_Buffer (Str, H3.Align(Get_Length(Str) + Act_Inc + 1, BUFFER_ALIGN), Act_Pos, Act_Inc);
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Str.Buffer.Slot(Act_Pos .. Act_Pos + Act_Inc - 1) := (others => V);
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end Insert;
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procedure Insert (Str: in out Elastic_String; Pos: in System_Index; V: in Character_Array) is
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Act_Pos: System_Index := Pos;
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begin
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if Act_Pos > Str.Buffer.Last then
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Act_Pos := Str.Buffer.Last + 1;
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end if;
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Prepare_Buffer (Str, H3.Align(Get_Length(Str) + V'Length + 1, BUFFER_ALIGN), Act_Pos, V'Length);
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Str.Buffer.Slot(Act_Pos .. Act_Pos + V'Length - 1) := V;
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end Insert;
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-- TODO: operator "&" that returns a new Elastic_String
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procedure Append (Str: in out Elastic_String; V: in Character_Type; Repeat: in System_Size := 1) is
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begin
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Insert (Str, Get_Last_Index(Str) + 1, V, Repeat);
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end Append;
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procedure Append (Str: in out Elastic_String; V: in Character_Array) is
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begin
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Insert (Str, Get_Last_Index(Str) + 1, V);
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end Append;
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procedure Prepend (Str: in out Elastic_String; V: in Character_Type; Repeat: in System_Size := 1) is
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begin
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Insert (Str, Get_First_Index(Str), V, Repeat);
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end Prepend;
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procedure Prepend (Str: in out Elastic_String; V: in Character_Array) is
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begin
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Insert (Str, Get_First_Index(Str), V);
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end Prepend;
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procedure Replace (Str: in out Elastic_String; From_Pos: in System_Index; To_Pos: in System_Size; V: in Character_Type; Repeat: in System_Size := 1) is
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Act_To_Pos, Repl_Len: System_Size;
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begin
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if From_Pos <= To_Pos and then From_Pos <= Str.Buffer.Last then
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Act_To_Pos := To_Pos;
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if Act_To_Pos > Str.Buffer.Last then
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Act_To_Pos := Str.Buffer.Last;
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end if;
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Repl_Len := Act_To_Pos - From_Pos + 1;
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if Repeat < Repl_Len then
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Prepare_Buffer (Str, Get_Hard_Capacity(Str), Act_To_Pos, Repl_Len - Repeat, SHIFT_LEFT);
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Act_To_Pos := From_Pos + Repeat - 1;
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elsif Repeat > Repl_Len then
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Prepare_Buffer (Str, Get_Hard_Capacity(Str), From_Pos, Repeat - Repl_Len, SHIFT_RIGHT);
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Act_To_Pos := From_Pos + Repeat - 1;
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else
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Prepare_Buffer (Str);
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end if;
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Str.Buffer.Slot(From_Pos .. Act_To_Pos) := (others => V);
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end if;
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end Replace;
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procedure Replace (Str: in out Elastic_String; From_Pos: in System_Index; To_Pos: in System_Size; V: in Character_Array) is
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Act_To_Pos, Repl_Len: System_Size;
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begin
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if From_Pos <= To_Pos and then From_Pos <= Str.Buffer.Last then
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Act_To_Pos := To_Pos;
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if Act_To_Pos > Str.Buffer.Last then
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Act_To_Pos := Str.Buffer.Last;
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end if;
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Repl_Len := Act_To_Pos - From_Pos + 1;
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if V'Length < Repl_Len then
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Prepare_Buffer (Str, Get_Hard_Capacity(Str), Act_To_Pos, Repl_Len - V'Length, SHIFT_LEFT);
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Act_To_Pos := From_Pos + V'Length - 1;
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elsif V'Length > Repl_Len then
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Prepare_Buffer (Str, Get_Hard_Capacity(Str), From_Pos, V'Length - Repl_Len, SHIFT_RIGHT);
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Act_To_Pos := From_Pos + V'Length - 1;
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else
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Prepare_Buffer (Str);
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end if;
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Str.Buffer.Slot(From_Pos .. Act_To_Pos) := V;
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end if;
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end Replace;
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procedure Delete (Str: in out Elastic_String; From_Pos: in System_Index; To_Pos: in System_Size) is
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Act_To_Pos: System_Size;
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begin
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if From_Pos <= To_Pos and then From_Pos <= Str.Buffer.Last then
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Act_To_Pos := To_Pos;
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if Act_To_Pos > Str.Buffer.Last then
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Act_To_Pos := Str.Buffer.Last;
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end if;
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Prepare_Buffer (Str, Get_Hard_Capacity(Str), Act_To_Pos, Act_To_Pos - From_Pos + 1, SHIFT_LEFT);
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end if;
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end Delete;
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function "=" (Str: in Elastic_String; Str2: in Elastic_String) return Standard.Boolean is
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begin
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return Str.Buffer = Str2.Buffer or else Str.Buffer.Slot(Get_First_Index(Str) .. Get_Last_Index(Str)) = Str2.Buffer.Slot(Get_First_Index(Str2) .. Get_Last_Index(Str2));
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end "=";
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function "=" (Str: in Elastic_String; Str2: in Character_Array) return Standard.Boolean is
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begin
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return Str.Buffer.Slot(Get_First_Index(Str) .. Get_Last_Index(Str)) = Str2;
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end "=";
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-- ---------------------------------------------------------------------
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-- Controlled Management
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-- ---------------------------------------------------------------------
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procedure Initialize (Str: in out Elastic_String) is
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begin
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-- the string is initialized to the empty buffer all the time.
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-- there is no need to reference the buffer.
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null;
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end Initialize;
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procedure Adjust (Str: in out Elastic_String) is
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begin
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Ref_Buffer (Str.Buffer);
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end Adjust;
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procedure Finalize (Str: in out Elastic_String) is
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begin
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Unref_Buffer (Str.Buffer);
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end Finalize;
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end H3.Strings;
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