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ILexer.cs
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/* M2Sharp -- Modula-2 to C# Translator & Compiler
*
* Copyright (c) 2016 The Modula-2 Software Foundation
*
* Author & Maintainer: Benjamin Kowarsch <trijezdci@org.m2sf>
*
* @synopsis
*
* M2Sharp is a multi-dialect Modula-2 to C# translator and via-C# compiler.
* It supports the dialects described in the 3rd and 4th editions of Niklaus
* Wirth's book "Programming in Modula-2" (PIM) published by Springer Verlag,
* and an extended mode with select features from the revised language by
* B.Kowarsch and R.Sutcliffe "Modula-2 Revision 2010" (M2R10).
*
* In translator mode, M2Sharp translates Modula-2 source to C# source files.
* In compiler mode, M2Sharp compiles Modula-2 source via C# source files
* to object code or executables using the host system's C# compiler.
*
* @repository
*
* https://github.com/m2sf/m2sharp
*
* @file
*
* ILexer.cs
*
* Public lexer interface.
*
* @license
*
* M2Sharp is free software: you can redistribute and/or modify it under the
* terms of the GNU Lesser General Public License (LGPL) either version 2.1
* or at your choice version 3 as published by the Free Software Foundation.
* However, you may not alter the copyright, author and license information.
*
* M2Sharp 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. Read the license for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with M2Sharp. If not, see <https://www.gnu.org/copyleft/lesser.html>.
*
* NB: Components in the domain part of email addresses are in reverse order.
*/
namespace org.m2sf.m2sharp {
/* ---------------------------------------------------------------------------
* Lexer status codes
* ------------------------------------------------------------------------ */
public enum LexerStatus {
Success,
FileNotFound,
FileAccessDenied,
NotInitialized,
TODO
} /* LexerStatus */
public interface ILexer {
/* ---------------------------------------------------------------------------
* Factory Methods
* ---------------------------------------------------------------------------
* Since C# does not fully support the concept of information hiding,
* factory methods are specified as comments for documentation purposes.
* The class constructor must be hidden to prevent clients from using it.
* ------------------------------------------------------------------------ */
/* ---------------------------------------------------------------------------
* Lexical limits
* ------------------------------------------------------------------------ */
uint MaxIdentLength (); /* default 32 */
uint CommentNestingLimit (); /* default 100 */
/* ---------------------------------------------------------------------------
* factory method newLexer(filename)
* ---------------------------------------------------------------------------
* Creates a new lexer instance, opens an input file, associates the file with
* the newly created lexer and returns a Result pair with the lexer reference
* and a status value.
*
* pre-conditions:
* o filename must refer to an existing and accessible input file
*
* post-conditions:
* o lexer is created
* o status is set to Success
*
* error-conditions:
* o if the file represented by filename cannot be found
* lexer is set to null, status is set to FileNotFound
* o if the file represented by filename cannot be accessed
* lexer is set to null, status is set to FileAccessDenied
* ----------------------------------------------------------------------- */
// public static Result<ILexer, LexerStatus> NewLexer (string filename);
/* --------------------------------------------------------------------------
* method ReadSym()
* --------------------------------------------------------------------------
* Reads the lookahead symbol from the source file associated with lexer and
* consumes it, thus advancing the current reading position, then returns
* the symbol's token.
*
* pre-conditions:
* o lexer instance must have been created with constructor NewLexer()
* so that it is associated with an input source file
*
* post-conditions:
* o character code of lookahead character or EOF is returned
* o current reading position and line and column counters are updated
* o file status is set to Success
*
* error-conditions:
* o if no source file is associated with lexer, no operation is carried out
* and status is set to NotInitialized
* ----------------------------------------------------------------------- */
Token ReadSym();
/* --------------------------------------------------------------------------
* method NextSym()
* --------------------------------------------------------------------------
* Reads the lookahead symbol from the source file associated with lexer but
* does not consume it, thus not advancing the current reading position,
* then returns the symbol's token.
*
* pre-conditions:
* o lexer instance must have been created with constructor NewLexer()
* so that it is associated with an input source file
*
* post-conditions:
* o token of lookahead symbol is returned
* o current reading position and line and column counters are NOT updated
* o file status is set to Success
*
* error-conditions:
* o if no source file is associated with lexer, no operation is carried out
* and status is set to NotInitialized
* ----------------------------------------------------------------------- */
Token NextSym ();
/* --------------------------------------------------------------------------
* method ConsumeSym()
* --------------------------------------------------------------------------
* Consumes the lookahead symbol and returns the token of the new lookahead
* symbol.
* ----------------------------------------------------------------------- */
Token ConsumeSym ();
/* --------------------------------------------------------------------------
* method Filename()
* --------------------------------------------------------------------------
* Returns the filename associated with the lexer instance.
* ----------------------------------------------------------------------- */
string Filename ();
/* --------------------------------------------------------------------------
* method Status()
* --------------------------------------------------------------------------
* Returns the status of the last operation on lexer.
* ----------------------------------------------------------------------- */
LexerStatus Status ();
/* --------------------------------------------------------------------------
* method LookaheadLexeme()
* --------------------------------------------------------------------------
* Returns the lexeme of the lookahead symbol.
* ----------------------------------------------------------------------- */
string LookaheadLexeme ();
/* --------------------------------------------------------------------------
* method CurrentLexeme()
* --------------------------------------------------------------------------
* Returns the lexeme of the most recently consumed symbol.
* ----------------------------------------------------------------------- */
string CurrentLexeme ();
/* --------------------------------------------------------------------------
* method LookaheadLine()
* --------------------------------------------------------------------------
* Returns the line counter of the lookahead symbol.
* ----------------------------------------------------------------------- */
uint LookaheadLine ();
/* --------------------------------------------------------------------------
* method CurrentLine()
* --------------------------------------------------------------------------
* Returns the line counter of the most recently consumed symbol.
* ----------------------------------------------------------------------- */
uint CurrentLine ();
/* --------------------------------------------------------------------------
* method lookaheadColumn()
* --------------------------------------------------------------------------
* Returns the column counter of the lookahead symbol.
* ----------------------------------------------------------------------- */
uint LookaheadColumn ();
/* --------------------------------------------------------------------------
* method CurrentColumn()
* --------------------------------------------------------------------------
* Returns the column counter of the most recently consumed symbol.
* ----------------------------------------------------------------------- */
uint CurrentColumn ();
/* --------------------------------------------------------------------------
* method PrintLineAndMarkColumn(line, column)
* --------------------------------------------------------------------------
* Prints the given source line of the current symbol to the console and
* marks the given coloumn with a caret '^'.
* ----------------------------------------------------------------------- */
void PrintLineAndMarkColumn (uint line, uint column);
} /* ILexer */
} /* namespace */
/* END OF FILE */