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jeremybenn |
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- G N A T . C G I --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2000-2009, AdaCore --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
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-- Boston, MA 02110-1301, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This is a package to interface a GNAT program with a Web server via the
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-- Common Gateway Interface (CGI).
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-- Other related packages are:
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-- GNAT.CGI.Cookie which deal with Web HTTP Cookies.
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-- GNAT.CGI.Debug which output complete CGI runtime environment
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-- Basically this package parse the CGI parameter which are a set of key/value
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-- pairs. It builds a table whose index is the key and provides some services
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-- to deal with this table.
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-- Example:
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-- Consider the following simple HTML form to capture a client name:
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-- <!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML 3.2//EN">
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-- <html>
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-- <head>
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-- <title>My Web Page</title>
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-- </head>
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-- <body>
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-- <form action="/cgi-bin/new_client" method="POST">
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-- <input type=text name=client_name>
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-- <input type=submit name="Enter">
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-- </form>
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-- </body>
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-- </html>
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-- The following program will retrieve the client's name:
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-- with GNAT.CGI;
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-- procedure New_Client is
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-- use GNAT;
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-- procedure Add_Client_To_Database (Name : String) is
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-- begin
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-- ...
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-- end Add_Client_To_Database;
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-- begin
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-- -- Check that we have 2 arguments (there is two inputs tag in
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-- -- the HTML form) and that one of them is called "client_name".
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-- if CGI.Argument_Count = 2
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-- and then CGI.Key_Exists ("client_name")
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-- then
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-- Add_Client_To_Database (CGI.Value ("client_name"));
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-- end if;
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-- ...
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-- CGI.Put_Header;
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-- Text_IO.Put_Line ("<html><body>< ... Ok ... >");
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-- exception
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-- when CGI.Data_Error =>
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-- CGI.Put_Header ("Location: /htdocs/error.html");
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-- -- This returns the address of a Web page to be displayed
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-- -- using a "Location:" header style.
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-- end New_Client;
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-- Note that the names in this package interface have been designed so that
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-- they read nicely with the CGI prefix. The recommended style is to avoid
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-- a use clause for GNAT.CGI, but to include a use clause for GNAT.
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-- This package builds up a table of CGI parameters whose memory is not
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-- released. A CGI program is expected to be a short lived program and
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-- so it is adequate to have the underlying OS free the program on exit.
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package GNAT.CGI is
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Data_Error : exception;
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-- This is raised when there is a problem with the CGI protocol. Either
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-- the data could not be retrieved or the CGI environment is invalid.
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--
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-- The package will initialize itself by parsing the runtime CGI
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-- environment during elaboration but we do not want to raise an
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-- exception at this time, so the exception Data_Error is deferred
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-- and will be raised when calling any services below (except for Ok).
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Parameter_Not_Found : exception;
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-- This exception is raised when a specific parameter is not found
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Default_Header : constant String := "Content-type: text/html";
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-- This is the default header returned by Put_Header. If the CGI program
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-- returned data is not an HTML page, this header must be change to a
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-- valid MIME type.
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type Method_Type is (Get, Post);
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-- The method used to pass parameter from the Web client to the
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-- server. With the GET method parameters are passed via the command
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-- line, with the POST method parameters are passed via environment
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-- variables. Others methods are not supported by this implementation.
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type Metavariable_Name is
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(Auth_Type,
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Content_Length,
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Content_Type,
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Document_Root, -- Web server dependent
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Gateway_Interface,
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HTTP_Accept,
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HTTP_Accept_Encoding,
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HTTP_Accept_Language,
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HTTP_Connection,
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HTTP_Cookie,
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HTTP_Extension,
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HTTP_From,
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HTTP_Host,
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HTTP_Referer,
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HTTP_User_Agent,
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Path,
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Path_Info,
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Path_Translated,
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Query_String,
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Remote_Addr,
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Remote_Host,
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Remote_Port, -- Web server dependent
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Remote_Ident,
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Remote_User,
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Request_Method,
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Request_URI, -- Web server dependent
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Script_Filename, -- Web server dependent
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Script_Name,
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Server_Addr, -- Web server dependent
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Server_Admin, -- Web server dependent
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Server_Name,
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Server_Port,
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Server_Protocol,
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Server_Signature, -- Web server dependent
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Server_Software);
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-- CGI metavariables that are set by the Web server during program
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-- execution. All these variables are part of the restricted CGI runtime
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-- environment and can be read using Metavariable service. The detailed
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-- meanings of these metavariables are out of the scope of this
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-- description. Please refer to http://www.w3.org/CGI/ for a description
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-- of the CGI specification. Some metavariables are Web server dependent
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-- and are not described in the cited document.
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procedure Put_Header
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(Header : String := Default_Header;
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Force : Boolean := False);
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-- Output standard CGI header by default. The header string is followed by
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-- an empty line. This header must be the first answer sent back to the
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-- server. Do nothing if this function has already been called and Force
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-- is False.
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function Ok return Boolean;
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-- Returns True if the CGI environment is valid and False otherwise.
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-- Every service used when the CGI environment is not valid will raise
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-- the exception Data_Error.
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function Method return Method_Type;
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-- Returns the method used to call the CGI
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function Metavariable
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(Name : Metavariable_Name;
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Required : Boolean := False) return String;
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-- Returns parameter Name value. Returns the null string if Name
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-- environment variable is not defined or raises Data_Error if
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-- Required is set to True.
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function Metavariable_Exists (Name : Metavariable_Name) return Boolean;
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-- Returns True if the environment variable Name is defined in
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-- the CGI runtime environment and False otherwise.
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function URL return String;
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-- Returns the URL used to call this script without the parameters.
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-- The URL form is: http://<server_name>[:<server_port>]<script_name>
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function Argument_Count return Natural;
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-- Returns the number of parameters passed to the client. This is the
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-- number of input tags in a form or the number of parameters passed to
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-- the CGI via the command line.
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---------------------------------------------------
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-- Services to retrieve key/value CGI parameters --
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---------------------------------------------------
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function Value
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(Key : String;
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Required : Boolean := False) return String;
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-- Returns the parameter value associated to the parameter named Key.
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-- If parameter does not exist, returns an empty string if Required
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-- is False and raises the exception Parameter_Not_Found otherwise.
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function Value (Position : Positive) return String;
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-- Returns the parameter value associated with the CGI parameter number
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-- Position. Raises Parameter_Not_Found if there is no such parameter
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-- (i.e. Position > Argument_Count)
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function Key_Exists (Key : String) return Boolean;
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-- Returns True if the parameter named Key exists and False otherwise
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function Key (Position : Positive) return String;
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-- Returns the parameter key associated with the CGI parameter number
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-- Position. Raises the exception Parameter_Not_Found if there is no
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-- such parameter (i.e. Position > Argument_Count)
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generic
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with procedure
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Action
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(Key : String;
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Value : String;
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Position : Positive;
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Quit : in out Boolean);
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procedure For_Every_Parameter;
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-- Iterate through all existing key/value pairs and call the Action
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-- supplied procedure. The Key and Value are set appropriately, Position
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-- is the parameter order in the list, Quit is set to True by default.
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-- Quit can be set to False to control the iterator termination.
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private
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function Decode (S : String) return String;
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-- Decode Web string S. A string when passed to a CGI is encoded,
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-- this function will decode the string to return the original
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-- string's content. Every triplet of the form %HH (where H is an
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-- hexadecimal number) is translated into the character such that:
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-- Hex (Character'Pos (C)) = HH.
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end GNAT.CGI;
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