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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Change uses of Unchecked_Deallocation (which is obsolete since Ada 95) to Ada.Unchecked_Deallocation to avoid warnings recently enabled in GNAT.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
172 lines
7.1 KiB
Ada
172 lines
7.1 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 is the root of the hierarchy that provides different encoding
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-- schemes.
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-- Each of the child package provides function to convert to and from
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-- Utf32-encoded string, which thus acts as the central encoding scheme.
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-- In some cases, the string can be preceded by a BOM (byte-order mark),
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-- that indicates the encoding used and the byte-order used for the
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-- encoding. This BOM is always optional, and can never be mixed up with
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-- other characters.
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with Ada.Unchecked_Deallocation;
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package Unicode.CES is
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-------------------
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-- Byte sequence --
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-------------------
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subtype Byte_Sequence is String;
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type Byte_Sequence_Access is access all Byte_Sequence;
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type Cst_Byte_Sequence_Access is access constant Byte_Sequence;
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-- A sequence of bytes. The encoding is unknown.
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procedure Free is new Ada.Unchecked_Deallocation
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(Byte_Sequence, Byte_Sequence_Access);
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-------------------------
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-- Byte order handling --
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-------------------------
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type Byte_Order is (High_Byte_First, Low_Byte_First);
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-- Order of bytes in word machines.
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Default_Byte_Order : constant Byte_Order := Low_Byte_First;
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------------------------------
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-- Byte-order mark handling --
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------------------------------
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type Bom_Type is
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(Utf8_All, -- Utf8-encoding
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Utf16_LE, -- Utf16 little-endian encoding
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Utf16_BE, -- Utf16 big-endian encoding
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Utf32_LE, -- Utf32 little-endian encoding
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Utf32_BE, -- Utf32 big-endian encoding
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Ucs4_BE, -- UCS-4, big endian machine (1234 order)
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Ucs4_LE, -- UCS-4, little endian machine (4321 order)
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Ucs4_2143, -- UCS-4, unusual byte order (2143 order)
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Ucs4_3412, -- UCS-4, unusual byte order (3412 order)
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Unknown); -- Unknown, assumed to be ASCII compatible
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-- the type of encoding used for a string, that can be deduced from the
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-- BOM.
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subtype Bom_Type_Utf16 is Bom_Type range Utf16_LE .. Utf16_BE;
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subtype Bom_Type_Utf32 is Bom_Type range Utf32_LE .. Utf32_BE;
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procedure Read_Bom
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(Str : String;
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Len : out Natural;
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BOM : out Bom_Type;
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XML_Support : Boolean := True);
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-- Read the optional Byte-Order-Mark at the beginning of the byte
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-- sequence Str.
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-- Len will contain the number of characters that made up that BOM, and
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-- that should be ignored when reading Str.
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-- If XML_Support is True, then the first four bytes of Str are also
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-- checked to recognize "<?xml", and thus distinguish in case there is no
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-- Byte-Order-Mark strictly speaking.
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function Write_Bom (BOM : Bom_Type) return String;
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-- Return a string suitable to output the BOM (Byte-order-mark). This
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-- should be added at the beginning of an output string, although this is
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-- not mandatory
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-----------------------
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-- Parsing functions --
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-----------------------
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-- All the packages in this hierarchy must provide at least two functions
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-- to read from a string (whatever its encoding).
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--
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-- These can be used to completly parse a string.
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-- J := Str'First;
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-- while J <= Str'Last loop
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-- C := Read (Str, J); -- Read the character
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-- J := J + Width (C); -- Move to the next
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-- end loop;
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type Read_Function is access
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procedure (Str : Byte_Sequence;
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Index : in out Positive;
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Char : out Unicode_Char);
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-- This function returns the character at position Index in the byte
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-- sequence Str, and moves Index to the start of the next character.
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-- If Str doesn't contain enough bytes for a valid encoding of a character,
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-- Incomplete_Encoding is raised.
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-- If Str contains an invalid byte sequence at Index, Invalid_Encoding
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-- is raised.
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type Width_Function is access
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function (Char : Unicode.Unicode_Char) return Natural;
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-- This function returns the number of bytes that encode Char in the
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-- specific encoding scheme.
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type Encode_Function is access
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procedure (Char : Unicode_Char;
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Output : in out Byte_Sequence;
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Index : in out Natural);
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-- This function converts Char to the appropriate byte sequence that
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-- represents it in the specific encoding.
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-- The byte sequence is stored in Output, starting at Index + 1. On exit,
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-- Index is left on the last character set in Output.
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type Length_Function is access
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function (Str : Byte_Sequence) return Natural;
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type Encoding_Scheme is record
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BOM : Bom_Type;
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Read : Read_Function;
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Width : Width_Function;
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Encode : Encode_Function;
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Length : Length_Function;
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end record;
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-- BOM is the byte-order mark to write when first writting a file with this
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-- encoding
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--------------------
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-- Misc functions --
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--------------------
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function Index_From_Offset
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(Str : Byte_Sequence; Offset : Natural; Encoding : Encoding_Scheme)
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return Integer;
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-- return the index in Str starting at Offset.
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-- (-1) is returned if Offset is invalid (outside of the range of Str).
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----------------
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-- Exceptions --
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----------------
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Invalid_Encoding : exception;
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-- Raised whenever the byte sequence associated with a given encoding
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-- scheme is not valid.
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Incomplete_Encoding : exception;
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-- Raised whenever the byte sequence associated with a given encoding
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-- scheme is incomplete.
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end Unicode.CES;
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