ADA Programming Guide

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Wrap

Text File | 1996-01-30 | 8KB | 277 lines

------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- I N T E R F A C E S . C . S T R I N G S -- -- -- -- B o d y -- -- -- -- $Revision: 1.9 $ -- -- -- -- Copyright (c) 1992,1993,1994 NYU, All Rights Reserved -- -- -- -- The GNAT library is free software; you can redistribute it and/or modify -- -- it under terms of the GNU Library General Public License as published by -- -- the Free Software Foundation; either version 2, or (at your option) any -- -- later version. The GNAT library is distributed in the hope that it will -- -- be useful, but WITHOUT ANY WARRANTY; without even the implied warranty -- -- of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -- -- Library General Public License for more details. You should have -- -- received a copy of the GNU Library General Public License along with -- -- the GNAT library; see the file COPYING.LIB. If not, write to the Free -- -- Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. -- -- -- ------------------------------------------------------------------------------ with System; use System; with System.Address_To_Access_Conversions; package body Interfaces.C.Strings is package Char_Access is new Address_To_Access_Conversions (char); ----------------------- -- Local Subprograms -- ----------------------- function Peek (From : chars_ptr) return char; pragma Inline (Peek); -- Given a chars_ptr value, obtain referenced character procedure Poke (Value : char; Into : chars_ptr); pragma Inline (Poke); -- Given a chars_ptr, modify referenced Character value function "+" (Left : chars_ptr; Right : size_t) return chars_ptr; pragma Inline ("+"); -- Address arithmetic on chars_ptr value function Position_Of_Nul (Into : char_array) return size_t; -- Returns position of the first Nul in Into or Into'Last + 1 if none function C_Malloc (Size : size_t) return chars_ptr; pragma Import (C, C_Malloc, "malloc"); procedure C_Free (Address : chars_ptr); pragma Import (C, C_Free, "free"); --------- -- "+" -- --------- function "+" (Left : chars_ptr; Right : size_t) return chars_ptr is begin return Left + chars_ptr (Right); end "+"; ---------- -- Free -- ---------- procedure Free (Item : in out chars_ptr) is begin if Item = Null_Ptr then return; end if; C_Free (Item); Item := Null_Ptr; end Free; -------------------- -- New_Char_Array -- -------------------- function New_Char_Array (Chars : in char_array) return chars_ptr is Index : size_t; Pointer : chars_ptr; begin -- Get index of position before null. This can be -1, which is OK! Index := Position_Of_Nul (Into => Chars) - 1; -- Returned value is length of signficant part + 1 for the nul character Pointer := C_Malloc ((Index - Chars'First + 1) + 1); Update (Item => Pointer, Offset => 0, Chars => Chars, Check => False); return Pointer; end New_Char_Array; ---------------- -- New_String -- ---------------- function New_String (Str : in String) return chars_ptr is begin return New_Char_Array (To_C (Str)); end New_String; ---------- -- Peek -- ---------- function Peek (From : chars_ptr) return char is use Char_Access; begin return To_Pointer (Address (To_Address (From))).all; end Peek; ---------- -- Poke -- ---------- procedure Poke (Value : char; Into : chars_ptr) is use Char_Access; begin To_Pointer (Address (To_Address (Into))).all := Value; end Poke; --------------------- -- Position_Of_Nul -- --------------------- function Position_Of_Nul (Into : char_array) return size_t is begin for J in Into'Range loop if Into (J) = nul then return J; end if; end loop; return Into'Last + 1; end Position_Of_Nul; ------------ -- Strlen -- ------------ function Strlen (Item : in chars_ptr) return size_t is Item_Index : size_t := 0; begin if Item = Null_Ptr then raise Dereference_Error; end if; loop if Peek (Item + Item_Index) = nul then return Item_Index; end if; Item_Index := Item_Index + 1; end loop; end Strlen; ------------------ -- To_Chars_Ptr -- ------------------ function To_Chars_Ptr (Item : in char_array_access; Nul_Check : in Boolean := False) return chars_ptr is begin if Item = null then return Null_Ptr; elsif Nul_Check and then Position_Of_Nul (Into => Item.all) > Item'Last then raise Terminator_Error; else return To_Integer (Item (Item'First)'Address); end if; end To_Chars_Ptr; ------------ -- Update -- ------------ procedure Update (Item : in chars_ptr; Offset : in size_t; Chars : in char_array; Check : Boolean := True) is Index : chars_ptr := Item + Offset; begin if Check and then Offset + Chars'Length > Strlen (Item) then raise Update_Error; end if; for J in Chars'Range loop Poke (Chars (J), Into => Index); Index := Index + 1; end loop; end Update; procedure Update (Item : in chars_ptr; Offset : in size_t; Str : in String; Check : in Boolean := True) is begin Update (Item, Offset, To_C (Str), Check); end Update; ----------- -- Value -- ----------- function Value (Item : in chars_ptr) return char_array is Result : char_array (0 .. Strlen (Item)); begin if Item = Null_Ptr then raise Dereference_Error; end if; -- Note that the following loop will also copy the terminating Nul for J in Result'Range loop Result (J) := Peek (Item + J); end loop; return Result; end Value; function Value (Item : in chars_ptr; Length : in size_t) return char_array is Result : char_array (0 .. Length - 1); begin if Item = Null_Ptr then raise Dereference_Error; end if; for J in Result'Range loop Result (J) := Peek (Item + J); if Result (J) = nul then return Result (0 .. J); end if; end loop; return Result; end Value; function Value (Item : in chars_ptr) return String is begin return To_Ada (Value (Item)); end Value; function Value (Item : in chars_ptr; Length : in size_t) return String is begin return To_Ada (Value (Item, Length)); end Value; end Interfaces.C.Strings;