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-- $Date: 2004/02/14 09:59:14 $
-- $Revision: 1.16 $
-- $Author: jcrocholl $
with Ada.Text_IO; use Ada.Text_IO;
with Strings; use Strings;
-- Light-weight text input file readers.
package Readers is
-- Light-weight text input file reader.
type Reader is tagged limited record
-- File access.
Filename : String_Access; -- Input file name.
File : File_Type; -- Input file handle.
-- Error messages.
Line_Number : Positive := 1; -- Line number in input file.
Column : Positive := 1; -- Index in current line.
-- Temporary data.
Char : Character; -- Look ahead character.
end record;
-- Access types for instance variables.
type Reader_Access is access Reader;
-------------------------------------------
-- Internal initialization and finalization
-------------------------------------------
-- These don't need to be called directly because the functions
-- Current_Input, Open and Close will do it for you.
-- Initialize a newly created reader instance.
procedure Initialize_Reader
(This : access Reader'Class); -- Initialize this reader.
-- Initialize a newly created reader instance with a file to read.
procedure Initialize_Reader
(This : access Reader'Class; -- Initialize this reader.
Filename : in String); -- Open this file for reading.
-- Close the input file.
procedure Finalize_Reader
(This : access Reader'Class); -- Finalize this reader.
-------------------
-- Creating readers
-------------------
-- Create a reader for current input (stdin).
function Current_Input
return Reader_Access; -- The newly created reader instance.
-- Create a reader for file input.
function Open
(Filename : in String) -- Open this file.
return Reader_Access; -- The newly created reader instance.
-- Close a reader's input file.
procedure Close
(This : in out Reader_Access); -- Close this reader.
--------------------------
-- Wrappers for file input
--------------------------
-- Check for end of line.
function End_Of_Line
(This : access Reader'Class) -- Check EOL on this reader.
return Boolean; -- End of line reached?
-- Check if the end of the input file has been reached.
function End_Of_File
(This : access Reader'Class) -- Check EOF on this reader.
return Boolean; -- End of input file?
-- Get the next input character into This.C.
procedure Get
(This : access Reader'Class); -- Get character for this reader.
-----------------
-- Error handling
-----------------
-- The input syntax has been violated.
Syntax_Error : exception;
-- Print an error message, then raise Syntax_Error.
procedure Error
(This : access Reader'Class; -- Print error about this reader.
Message : in String); -- Print this message.
-- Concatenate two strings in a special format acceptable for
-- expectation errors.
function "/"
(A, B : in String) -- Join these strings.
return String; -- The combination with some joining text.
-- Print a formatted error message for unmatched expectations, then
-- raise Syntax_Error.
procedure Expect_Error
(This : access Reader'Class; -- Print error about this reader.
Found : in String; -- But this text was found.
Choices : in String); -- This text was expected.
---------------------
-- Reading characters
---------------------
-- Read the current character.
function Get_Char
(This : access Reader'Class) -- Use this reader.
return Character; -- The character that was read.
-- Check if a given token was found.
function Found_Char
(This : access Reader'Class; -- Check character in this reader.
Char : in Character) -- Check if this character was found.
return Boolean; -- True if the given character was found.
-- Test if the current look-ahead character is what we expect.
-- Call Error if not, and that raises Syntax_Error.
procedure Assert_Char
(This : access Reader'Class; -- Check character in this reader.
Char : in Character); -- Expect this character.
end Readers;