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/*

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 * (c) 2003 Mario de Sousa

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 *

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 * Offered to the public under the terms of the GNU General Public License

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 * as published by the Free Software Foundation; either version 2 of the

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 * License, or (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, but

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 * WITHOUT ANY WARRANTY; without even the implied warranty of

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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General

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 * Public License for more details.

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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 IL and ST 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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 * VISITOR.HH

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 *

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 *

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 * The asbract syntax tree is scaned several times

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 * during the whole compilation process. For e.g., stage 3 verifies

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 * semantics, and stage 4 produces output.

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 *

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 * Since the number of functions that need to scan through

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 * the abtract syntax tree may increase in time, (e.g. new

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 * output formats, new semantic checks, etc...) while the

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 * abstract syntax tree class structure is pretty stable

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 * (i.e. the ST and IL languages will not be changing much...),

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 * we use the 'visitor' design patern.

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 *

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 * It is not strictly necessary to use this pattern, but it does

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 * have the advantage of bringing together the functions

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 * that implement the same algorithm, each on a different

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 * class of object in the abstract syntax tree.

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 *

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 *

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 * This file contains the interface that each visitor class

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 * must implement in order to be able to visit the abstract

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 * syntax tree (class visitor_c)

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 *

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 * Three implementations of this interface are also provided,

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 * that may be later extended to execute a particular algorithm.

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 *

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 * The null (class null_visitor_c) does nothing.

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 *

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 * The iterator (class iterator_visitor_c) iterates through

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 * every object in the syntax tree.

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 *

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 * The search class (class search_visitor_c) iterates through

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 * every object, until one returns a value != NULL.

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 */

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#ifndef _VISITOR_HH

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#define _VISITOR_HH

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#include "absyntax.hh"

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#define SYM_LIST(class_name_c)	\

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  virtual void *visit(class_name_c *symbol) = 0;

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#define SYM_TOKEN(class_name_c)	\

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  virtual void *visit(class_name_c *symbol) = 0;

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#define SYM_REF0(class_name_c)	\

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  virtual void *visit(class_name_c *symbol) = 0;

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#define SYM_REF2(class_name_c, ref1, ref2)	\

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  virtual void *visit(class_name_c *symbol) = 0;

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#define SYM_REF4(class_name_c, ref1, ref2, ref3, ref4)	\

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  virtual void *visit(class_name_c *symbol) = 0;

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#define SYM_REF6(class_name_c, ref1, ref2, ref3, ref4, ref5, ref6)	\

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  virtual void *visit(class_name_c *symbol) = 0;

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class visitor_c {

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  public:

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  #include "absyntax.def"

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  virtual ~visitor_c(void);

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};

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#undef SYM_LIST

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#undef SYM_TOKEN

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#undef SYM_REF0

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#undef SYM_REF2

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#undef SYM_REF4

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#undef SYM_REF6

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#define SYM_LIST(class_name_c)	\

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  virtual void *visit(class_name_c *symbol);

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#define SYM_TOKEN(class_name_c)	\

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  virtual void *visit(class_name_c *symbol);

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#define SYM_REF0(class_name_c)	\

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  virtual void *visit(class_name_c *symbol);

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#define SYM_REF2(class_name_c, ref1, ref2)	\

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  virtual void *visit(class_name_c *symbol);

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#define SYM_REF4(class_name_c, ref1, ref2, ref3, ref4)	\

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  virtual void *visit(class_name_c *symbol);

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#define SYM_REF6(class_name_c, ref1, ref2, ref3, ref4, ref5, ref6)	\

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  virtual void *visit(class_name_c *symbol);

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class null_visitor_c: public visitor_c {

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  public:

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  #include "absyntax.def"

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  virtual ~null_visitor_c(void);

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};

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class iterator_visitor_c: public visitor_c {

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  protected:

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  void *visit_list(list_c *list);

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  public:

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  #include "absyntax.def"

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  virtual ~iterator_visitor_c(void);

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};

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class search_visitor_c: public visitor_c {

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  protected:

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  void *visit_list(list_c *list);

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  public:

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  #include "absyntax.def"

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  virtual ~search_visitor_c(void);

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};

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#undef SYM_LIST

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#undef SYM_TOKEN

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#undef SYM_REF0

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#undef SYM_REF2

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#undef SYM_REF4

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#undef SYM_REF6

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#endif /*  _VISITOR_HH */