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/*

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 *  matiec - a compiler for the programming languages defined in IEC 61131-3

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 *

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 *  Copyright (C) 2003-2011  Mario de Sousa (msousa@fe.up.pt)

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 *

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 *  This program is free software: you can redistribute it and/or modify

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 *  it under the terms of the GNU General Public License as published by

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 *  the Free Software Foundation, either version 3 of thest_whitespaceLicense, or

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 *  (at your option) any later version.

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 *

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 *  This program is distributed in the hope that it will be useful,

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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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 *  You should have received a copy of the GNU General Public License

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 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

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 *

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 *

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 * This code is made available on the understanding that it will not be

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 * used in safety-critical situations without a full and competent review.

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 */

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/*

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 * An IEC 61131-3 compiler.

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 *

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 * Based on the

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 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

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 *

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 */

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/*

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 * Stage 1

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 * =======

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 *

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 * This file contains the lexical tokens definitions, from which

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 * the flex utility will generate a lexical parser function.

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 */

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/*****************************/

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/* Lexical Parser Options... */

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/*****************************/

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/* The lexical analyser will never work in interactive mode,

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 * i.e., it will only process programs saved to files, and never

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 * programs being written inter-actively by the user.

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 * This option saves the resulting parser from calling the

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 * isatty() function, that seems to be generating some compile

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 * errors under some (older?) versions of flex.

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 */

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%option never-interactive

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/* Have the lexical analyser use a 'char *yytext' instead of an

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 * array of char 'char yytext[??]' to store the lexical token.

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 */

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%pointer

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/* Have the lexical analyser ignore the case of letters.

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 * This will occur for all the tokens and keywords, but

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 * the resulting text handed up to the syntax parser

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 * will not be changed, and keep the original case

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 * of the letters in the input file.

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 */

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%option case-insensitive

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/* Have the generated lexical analyser keep track of the

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 * line number it is currently analysing.

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 * This is used to pass up to the syntax parser

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 * the number of the line on which the current

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 * token was found. It will enable the syntax parser

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 * to generate more informatve error messages...

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 */

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%option yylineno

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/* required for the use of the yy_pop_state() and

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 * yy_push_state() functions

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 */

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%option stack

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/* The '%option stack' also requests the inclusion of 

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 * the yy_top_state(), however this function is not

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 * currently being used. This means that the compiler

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 * is complaining about the existance of this function.

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 * The following option removes the yy_top_state()

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 * function from the resulting c code, so the compiler 

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 * no longer complains.

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 */

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%option noyy_top_state

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/* We will be using unput() in our flex code, so we cannot set the following option!... */

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/*

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%option nounput

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*/

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/* The '%option debug' makes the generated scanner run in

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 * debug mode.

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%option debug

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 */

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/**************************************************/

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/* External Variable and Function declarations... */

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/**************************************************/

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%{

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/* Define TEST_MAIN to include a main() function.

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 * Useful for testing the parser generated by flex.

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 */

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/*

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#define TEST_MAIN

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*/

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/* If lexical parser is compiled by itself, we need to define the following

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 * constant to some string. Under normal circumstances LIBDIRECTORY is set

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 * in the syntax parser header file...

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 */

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#ifdef TEST_MAIN

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#define DEFAULT_LIBDIR "just_testing"

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#endif

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/* Required for strdup() */

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#include <string.h>

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/* Required only for the declaration of abstract syntax classes

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 * (class symbol_c; class token_c; class list_c;)

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 * These will not be used in flex, but the token type union defined

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 * in iec_bison.hh contains pointers to these classes, so we must include

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 * it here.

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 */

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#include "../absyntax/absyntax.hh"

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/* iec_bison.hh is generated by bison.

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 * Contains the definition of the token constants, and the

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 * token value type YYSTYPE (in our case, a 'const char *')

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 */

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#include "iec_bison.hh"

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#include "stage1_2_priv.hh"

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/* Variable defined by the bison parser,

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 * where the value of the tokens will be stored

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 */

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extern YYSTYPE yylval;

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/* The name of the file currently being parsed...

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 * Note that flex accesses and updates this global variable

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 * apropriately whenever it comes across an (*#include <filename> *) directive...

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 */

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const char *current_filename = NULL;

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/* Variable defined by the bison parser.

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 * It must be initialised with the location

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 * of the token being parsed.

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 * This is only needed if we want to keep

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 * track of the locations, in order to give

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 * more meaningful error messages!

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 */

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/*

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 *extern YYLTYPE yylloc;

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b*/

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#define YY_INPUT(buf,result,max_size)  {\

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    result = GetNextChar(buf, max_size);\

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    if (  result <= 0  )\

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      result = YY_NULL;\

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    }

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/* Macro that is executed for every action.

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 * We use it to pass the location of the token

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 * back to the bison parser...

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 */

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#define YY_USER_ACTION {\

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	current_tracking->currentTokenStart = current_tracking->currentChar;	\

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	current_order++;							\

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	}

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/* Since this lexical parser we defined only works in ASCII based

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 * systems, we might as well make sure it is being compiled on

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 * one...

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 * Lets check a few random characters...

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 */

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#if (('a' != 0x61) || ('A' != 0x41) || ('z' != 0x7A) || ('Z' != 0x5A) || \

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     ('0' != 0x30) || ('9' != 0x39) || ('(' != 0x28) || ('[' != 0x5B))

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#error This lexical analyser is not portable to a non ASCII based system.

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#endif

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/* Function only called from within flex, but defined

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 * in iec.y!

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 * We declare it here...

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 *

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 * Search for a symbol in either of the two symbol tables

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 * and return the token id of the first symbol found.

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 * Searches first in the variables, and only if not found

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 * does it continue searching in the library elements

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 */

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//token_id_t get_identifier_token(const char *identifier_str);

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int get_identifier_token(const char *identifier_str);

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%}

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/***************************************************/

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/* Forward Declaration of functions defined later. */

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/***************************************************/

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%{

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/* return all the text in the current token back to the input stream. */

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/* return all the text in the current token back to the input stream, 

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 * but first return to the stream an additional character to mark the end of the token. 

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 */

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void include_file(const char *include_filename);

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/* The body_state tries to find a ';' before a END_PROGRAM, END_FUNCTION or END_FUNCTION_BLOCK or END_ACTION

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 * once we have decided if we are parsing ST or IL code. The following functions manage that buffer used by

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 * the body_state.

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 */

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void   unput_bodystate_buffer(void);

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int  isempty_bodystate_buffer(void);

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int GetNextChar(char *b, int maxBuffer);

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%}

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   254

   255

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/****************************/

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/* Lexical Parser States... */

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/****************************/

   259

   260

/* NOTE: Our psrser can parse st or il code, intermixed

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 *       within the same file.

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 *       With IL we come across the issue of the EOL (end of line) token.

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 *       ST, and the declaration parts of IL do not use this token!

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 *       If the lexical analyser were to issue this token during ST

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 *       language parsing, or during the declaration of data types,

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 *       function headers, etc. in IL, the syntax parser would crash.

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 *

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 *       We can solve this issue using one of three methods:

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 *        (1) Augment all the syntax that does not accept the EOL

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 *            token to simply ignore it. This makes the syntax

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 *            definition (in iec.y) very cluttered!

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 *        (2) Let the lexical parser figure out which language

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 *            it is parsing, and decide whether or not to issue

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 *            the EOL token. This requires the lexical parser

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 *            to have knowledge of the syntax!, making for a poor

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 *            overall organisation of the code. It would also make it

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 *            very difficult to understand the lexical parser as it

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 *            would use several states, and a state machine to transition

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 *            between the states. The state transitions would be

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 *            intermingled with the lexical parser defintion!

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 *        (3) Use a mixture of (1) and (2). The lexical analyser

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 *            merely distinguishes between function headers and function

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 *            bodies, but no longer makes a distinction between il and

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 *            st language bodies. When parsing a body, it will return

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 *            the EOL token. In other states '\n' will be ignored as

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 *            whitespace.

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 *            The ST language syntax has been augmented in the syntax

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 *            parser configuration to ignore any EOL tokens that it may

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 *            come across!

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 *            This option has both drawbacks of option (1) and (2), but

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 *            much less intensely.

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 *            The syntax that gets cluttered is limited to the ST statements

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 *            (which is rather limited, compared to the function headers and

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 *            data type declarations, etc...), while the state machine in

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 *            the lexical parser becomes very simple. All state transitions

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 *            can be handled within the lexical parser by itself, and can be

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 *            easily identified. Thus knowledge of the syntax required by

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 *            the lexical parser is very limited!

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 *

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 * Amazingly enough, I (Mario) got to implement option (3)

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 * at first, requiring two basic states, decl and body.

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 * The lexical parser will enter the body state when

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 * it is parsing the body of a function/program/function block. The

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 * state transition is done when we find a VAR_END that is not followed

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 * by a VAR! This is the syntax knowledge that gets included in the

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 * lexical analyser with this option!

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 * Unfortunately, getting the st syntax parser to ignore EOL anywhere

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 * where they might appear leads to conflicts. This is due to the fact

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 * that the syntax parser uses the single look-ahead token to remove

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 * possible conflicts. When we insert a possible EOL, the single

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 * look ahead token becomes the EOL, which means the potential conflicts

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 * could no longer be resolved.

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 * Removing these conflicts would make the st syntax parser very convoluted,

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 * and adding the extraneous EOL would make it very cluttered.

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 * This option was therefore dropped in favour of another!

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 *

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 * I ended up implementing (2). Unfortunately the lexical analyser can

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 * not easily distinguish between il and st code, since function

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 * calls in il are very similar to function block calls in st.

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 * We therefore use an extra 'body' state. When the lexical parser

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 * finds that last END_VAR, it enters the body state. This state

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 * must figure out what language is being parsed from the first few

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 * tokens, and switch to the correct state (st, il or sfc) according to the

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 * language. This means that we insert quite a bit of knowledge of the

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 * syntax of the languages into the lexical parser. This is ugly, but it

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 * works, and at least it is possible to keep all the state changes together

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 * to make it easier to remove them later on if need be.

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 * Once the language being parsed has been identified, 

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 * the body state returns any matched text back to the buffer with unput(),

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 * to be later matched correctly by the apropriate language parser (st, il or sfc).

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 *

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 * Aditionally, in sfc state it may further recursively enter the body state

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 * once again. This is because an sfc body may contain ACTIONS, which are then

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 * written in one of the three languages (ST, IL or SFC), so once again we need

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 * to figure out which language the ACTION in the SFC was written in. We already

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 * ahve all that done in the body state, so we recursively transition to the body 

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 * state once again.

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 * Note that in this case, when coming out of the st/il state (whichever language

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 * the action was written in) the sfc state will become active again. This is done by

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 * pushing and poping the previously active state!

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 *

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 * The sfc_qualifier_state is required because when parsing actions within an

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 * sfc, we will be expecting action qualifiers (N, P, R, S, DS, SD, ...). In order

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 * to bison to work correctly, these qualifiers must be returned as tokens. However,

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 * these tokens are not reserved keywords, which means it should be possible to

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 * define variables/functions/FBs with any of these names (including 

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 * S and R which are special because they are also IL operators). So, when we are not

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 * expecting any action qualifiers, flex does not return these tokens, and is free

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 * to interpret them as previously defined variables/functions/... as the case may be.

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 *

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 * The time_literal_state is required because TIME# literals are decomposed into 

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 * portions, and wewant to send these portions one by one to bison. Each poertion will 

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 * represent the value in days/hours/minutes/seconds/ms.

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 * Unfortunately, some of these portions may also be lexically analysed as an identifier. So,

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 * we need to disable lexical identification of identifiers while parsing TIME# literals!

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 * e.g.:  TIME#55d_4h_56m

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 *       We would like to return to bison the tokens 'TIME' '#' '55d' '_' '4h' '_' '56m'

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 *       Unfortunately, flex will join '_' and '4h' to create a legal {identifier} '_4h',

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 *       and return that identifier instead! So, we added this state!

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 *

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 * The ignore_pou_state state is only used when bison says it is doing the pre-parsing.

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 * During pre-parsing, the main state machine will only transition between

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 * INITIAL and ignore_pou_state, and from here back to INITIAL. All other

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 * transitions are inhibited. This inhibition is actually just enforced by making

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 * sure that the INITIAL ---> ignore_pou_state transition is tested before all other

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 * transitions coming out of INITIAL state. All other transitions are unaffected, as they

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 * never get a chance to be evaluated when bison is doing pre-parsing.

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 * Pre-parsing is a first quick scan through the whole input source code simply

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 * to determine the list of POUs and datatypes that will be defined in that

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 * code. Basically, the objective is to fill up the previously_declared_xxxxx

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 * maps, without processing the code itself. Once these maps have been filled up,

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 * bison will throw away the AST (abstract syntax tree) created up to that point, 

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 * and scan through the same source code again, but this time creating a correct AST.

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 * This pre-scan allows the source code to reference POUs and datatypes that are

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 * only declared after they are used!

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 * 

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 *

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 * Here is a main state machine...

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 *                                                                         --+  

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 *                                                                           |  these states are

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 *              +------------> get_pou_name_state  ----> ignore_pou_state    |  only active 

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 *              |                                            |               |  when bison is 

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 *              |  ------------------------------------------+               |  doing the 

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 *              |  |                                                         |  pre-parsing!!

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 *              |  v                                                       --+

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 *       +---> INITIAL <-------> config

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 *       |        \

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 *       |        V

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 *       |   header_state

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 *       |        |

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 *       |        V

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 *     vardecl_list_state <------> var_decl

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 *       ^        | 

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 *       |        | [using push()]

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 *       |        |

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 *       |        V

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 *       |       body, 

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 *       |        |

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 *       |        | 

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 *       |   -------------------

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 *       |   |       |         |

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 *       |   v       v         v

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 *       |  st      il        sfc

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 *       |   |       |         |  [using pop() when leaving st/il/sfc => goes to vardecl_list_state]

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 *       |   |       |         |

   406

 *       -----------------------

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 *

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 * NOTE:- When inside sfc, and an action or transition in ST/IL is found, then 

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 *        we also push() to the body state. This means that sometimes, when pop()ing

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 *        from st and il, the state machine may return to the sfc state!

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 *      - The transitions form sfc to body will be decided by bison, which will

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 *        tell flex to do the transition by calling cmd_goto_body_state().

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 *   

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 * 

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 * Possible state changes are:

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 *   INITIAL -> goto(ignore_pou_state)

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 *               (This transition state is only used when bison says it is doing the pre-parsing.)

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 *               (This transition takes precedence over all other transitions!)

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 *               (when a FUNCTION, FUNCTION_BLOCK, PROGRAM or CONFIGURATION is found)

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 * 

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 *   INITIAL -> goto(config_state)

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 *                (when a CONFIGURATION is found)

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 * 

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 *   INITIAL -> goto(header_state)

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 *               (when a FUNCTION, FUNCTION_BLOCK, or PROGRAM is found)

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 * 

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 *   header_state -> goto(vardecl_list_state)

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 *               (When the first VAR token is found, i.e. at begining of first VAR .. END_VAR declaration)

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 * 

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 *  vardecl_list_state -> push current state (vardecl_list_state), and goto(vardecl_state) 

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 *                (when a VAR token is found)

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 *   vardecl_state -> pop() to (vardecl_list_state) 

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 *                (when a END_VAR token is found)

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 * 

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 *   vardecl_list_state -> push current state (vardecl_list_state), and goto(body_state) 

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 *                (when the last END_VAR is found!)

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 *

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 *   body_state    -> goto(sfc_state)

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 *                     (when it figures out it is parsing sfc language)

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 *   body_state    -> goto(st_state)

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 *                     (when it figures out it is parsing st language)

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 *   body_state    -> goto(il_state)

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 *                     (when it figures out it is parsing il language)

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 *   st_state      -> pop() to vardecl_list_state

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 *                     (when a END_FUNCTION, END_FUNCTION_BLOCK, END_PROGRAM,

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 *                      END_ACTION or END_TRANSITION is found)

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 *   il_state      -> pop() to vardecl_list_state

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 *                     (when a END_FUNCTION, END_FUNCTION_BLOCK, END_PROGRAM,

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 *                      END_ACTION or END_TRANSITION is found)

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 *   sfc_state     -> pop() to vardecl_list_state

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 *                     (when a END_FUNCTION, END_FUNCTION_BLOCK, or END_PROGRAM is found)

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 * 

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 *   ignore_pou_state   -> goto(INITIAL)

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 *                         (when a END_FUNCTION, END_FUNCTION_BLOCK, END_PROGRAM or END_CONFIGURATION is found)

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 *   vardecl_list_state -> goto(INITIAL)

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 *                         (when a END_FUNCTION, END_FUNCTION_BLOCK, or END_PROGRAM is found)

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 *   config_state       -> goto(INITIAL)

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 *                         (when a END_CONFIGURATION is found)

   459

 * 

   460

 *  

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 *   sfc_state     -> push current state(sfc_state); goto(body_state)

   462

 *                     (when parsing an action. This transition is requested by bison)

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 *   sfc_state     -> push current state(sfc_state); goto(sfc_qualifier_state)

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 *                     (when expecting an action qualifier. This transition is requested by bison)

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 *   sfc_qualifier_state -> pop() to sfc_state

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 *                     (when no longer expecting an action qualifier. This transition is requested by bison)

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 *

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 *   config_state  -> push(config_state); goto(task_init_state)

   469

 *                     (when parsing a task initialisation. This transition is requested by bison)

   470

 *   task_init_state -> pop()

   471

 *                     (when no longer parsing task initialisation parameters. This transition is requested by bison)

   472

 *

   473

 * 

   474

 * There is another secondary state machine for parsing comments, another for file_includes, 

   475

 * and yet another for time literals.

   476

 */

   477

   478

   479

/* Bison is in the pre-parsing stage, and we are parsing a POU. Ignore everything up to the end of the POU! */

   480

%x ignore_pou_state

   481

%x get_pou_name_state

   482

   483

/* we are parsing a configuration. */

   484

%s config_state

   485

   486

/* Inside a configuration, we are parsing a task initialisation parameters */

   487

/* This means that PRIORITY, SINGLE and INTERVAL must be handled as

   488

 * tokens, and not as possible identifiers. Note that the above words

   489

 * are not keywords.

   490

 */

   491

%s task_init_state

   492

   493

/* we are looking for the first VAR inside a function's, program's or function block's declaration */

   494

/* This is not exclusive (%x) as we must be able to parse the identifier and data types of a function/FB */

   495

%s header_state

   496

   497

/* we are parsing a function, program or function block sequence of VAR..END_VAR delcarations */

   498

%x vardecl_list_state 

   499

/* a substate of the vardecl_list_state: we are inside a specific VAR .. END_VAR */

   500

%s vardecl_state

   501

   502

/* we will be parsing a function body/action/transition. Whether il/st/sfc remains to be determined */

   503

%x body_state

   504

   505

/* we are parsing il code -> flex must return the EOL tokens!       */