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7446ee5ee3
Change uses of Unchecked_Deallocation (which is obsolete since Ada 95) to Ada.Unchecked_Deallocation to avoid warnings recently enabled in GNAT. Update copyright headers. TN: V614-004 TN: V209-051 Change-Id: I6aa7dbeeeecadf6a9d0b5f0aafb0167dc22dfd51
168 lines
6.7 KiB
Ada
168 lines
6.7 KiB
Ada
------------------------------------------------------------------------------
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-- XML/Ada - An XML suite for Ada95 --
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-- --
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-- Copyright (C) 2001-2022, AdaCore --
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-- --
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-- This library is free software; you can redistribute it and/or modify it --
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-- under terms of the GNU General Public License as published by the Free --
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-- Software Foundation; either version 3, or (at your option) any later --
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-- version. This library is distributed in the hope that it will be useful, --
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN- --
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-- TABILITY or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides support for Utf16 encoding of characters.
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--
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-- Although utf32 is simpler, it requires too much space to encode typical
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-- strings. Indeed, only two bytes are currently needed to encode every
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-- unicode character. Thus, utf16 was created in that purpose. Most characters
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-- are encoded only on two bytes, although there is provision for a four-byte
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-- encoding in some cases, using what is known as surrogate pairs.
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--
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-- As a result, utf16 is a variable-width encoding, and traversing a string is
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-- a little bit less efficient that with Utf32.
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--
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-- Another inconvenient is that you can not easily search an ASCII character
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-- in a string with the standard string manipulation functions, since you
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-- might find the high-byte of a two-byte sequence.
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with Ada.Unchecked_Deallocation;
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with Unicode.CES.Utf32;
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with Unicode.CCS;
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package Unicode.CES.Utf16 is
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-----------
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-- Types --
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-----------
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subtype Utf16_String is String;
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type Utf16_String_Access is access Utf16_String;
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-- A UTF16-encoded string, undefined byte-order
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subtype Utf16_LE_String is Utf16_String;
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type Utf16_LE_String_Access is access Utf16_LE_String;
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-- Similar, but with little-endian byte-order
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subtype Utf16_BE_String is Utf16_String;
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-- Similar, but with big-endian byte-order
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-------------------------------------------
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-- Conversion to and from byte sequences --
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-------------------------------------------
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procedure Encode
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(Char : Unicode_Char;
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Output : in out Byte_Sequence;
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Index : in out Natural);
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-- Return the byte sequence representing Char in the Utf16 character
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-- encoding form (little-endian)
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procedure Read
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(Str : Utf16_LE_String;
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Index : in out Positive;
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Char : out Unicode_Char);
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-- Return the character starting at location Index in Str
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-- Invalid_Encoding is raised if not valid byte sequence starts at Index.
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-- Incomplete_Encoding is raised if there is not enough characters for
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-- a valid encoding.
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procedure Read_BE
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(Str : Utf16_BE_String;
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Index : in out Positive;
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Char : out Unicode_Char);
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-- Return the character starting at location Index in Str (big-endian)
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procedure Encode_BE
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(Char : Unicode_Char;
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Output : in out Byte_Sequence;
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Index : in out Natural);
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-- Return the byte sequence representing Char in the Utf16 character
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-- encoding form (big-endian)
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function Width (Char : Unicode_Char) return Natural;
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-- Return the number of bytes occupied by the Utf16 representation of Char
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function Length (Str : Utf16_String) return Natural;
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-- Return the number of characters in Str
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-------------------------------------------
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-- Conversion to and from Utf32-encoding --
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-------------------------------------------
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function From_Utf32
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(Str : Unicode.CES.Utf32.Utf32_LE_String)
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return Utf16_LE_String;
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-- Return a new utf16-encoded string, from a Utf32-encoded string.
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function To_Utf32
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(Str : Utf16_LE_String)
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return Unicode.CES.Utf32.Utf32_LE_String;
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-- Return a new utf32-encoded string, from a Utf16-encoded string.
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---------------------------
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-- Byte order conversion --
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---------------------------
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function To_Unicode_LE
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(Str : Utf16_String;
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Cs : Unicode.CCS.Character_Set := Unicode.CCS.Unicode_Character_Set;
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Order : Byte_Order := Default_Byte_Order) return Utf16_LE_String;
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-- Convert Str to a Unicode, little-endian utf16-encoding byte sequence.
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-- Order is the order in which bytes are coded in Str. This is silently
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-- overriden in case Str as a BOM (byte-order-marker) at the beginning
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-- that specifies an explicit order.
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-- The BOM is removed from the resulting string
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-- Invalid_Encoding is raised if Str contains a BOM that indicates an
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-- encoding other than Utf16.
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function To_CS
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(Str : Utf16_LE_String;
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Cs : Unicode.CCS.Character_Set := Unicode.CCS.Unicode_Character_Set;
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Order : Byte_Order := Default_Byte_Order) return Utf16_String;
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-- Convert Str from Unicode to another character set, and possibly
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-- another ordering.
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-- No BOM is checked
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---------------------
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-- Encoding Scheme --
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---------------------
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Utf16_LE_Encoding : constant Encoding_Scheme :=
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(BOM => Utf16_LE,
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Read => Read'Access,
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Width => Width'Access,
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Encode => Encode_Function'(Encode'Access),
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Length => Length'Access);
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Utf16_BE_Encoding : constant Encoding_Scheme :=
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(BOM => Utf16_BE,
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Read => Read_BE'Access,
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Width => Width'Access,
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Encode => Encode_Function'(Encode_BE'Access),
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Length => Length'Access);
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------------------
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-- Deallocation --
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------------------
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procedure Free is new Ada.Unchecked_Deallocation
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(Utf16_String, Utf16_String_Access);
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procedure Free is new Ada.Unchecked_Deallocation
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(Utf16_LE_String, Utf16_LE_String_Access);
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-- Free the memory occupied by a utf16-encoded string
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private
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pragma Inline (Width);
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end Unicode.CES.Utf16;
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