--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/stage3/remove_forward_dependencies.hh	Sat Dec 06 19:14:23 2014 +0000
@@ -0,0 +1,115 @@
+/*
+ *  matiec - a compiler for the programming languages defined in IEC 61131-3
+ *
+ *  Copyright (C) 2014  Mario de Sousa (msousa@fe.up.pt)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * This code is made available on the understanding that it will not be
+ * used in safety-critical situations without a full and competent review.
+ */
+
+/*
+ * An IEC 61131-3 compiler.
+ *
+ * Based on the
+ * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
+ *
+ */
+
+
+/*
+ * Re-oder the POUs in te library so that no forward references occur.
+ * 
+ * Since stage1_2 now suppport POUs that contain references to POUS that are only declared later,
+ * (e.g. a variable of FB1_t is declared, before the FB1_T function block is itself declared!)
+ * we may need to re-order all the POUs in the library so that these forward references do not occur.
+ * 
+ * This utility class will do just that. However, it does not destroy the original abstract syntax 
+ * tree (AST). It instead creates a new re-ordered AST, by instantiating a new library_c object.
+ * This new library_c object will however point to the *same* objects of the original AST, just in 
+ * a new order. 
+ * This means that the new and original AST share all the object instances, and only use a distinct
+ * library_c object!
+ */
+
+#include "../absyntax/absyntax.hh"
+#include "../absyntax/visitor.hh"
+#include "../util/symtable.hh"
+#include <set>
+
+
+class   find_forward_dependencies_c;
+extern  symbol_c remove_forward_dependencies_c_null_symbol;
+typedef symtable_c<symbol_c *, &remove_forward_dependencies_c_null_symbol> identifiers_symbtable_t;
+
+
+
+
+
+
+
+class remove_forward_dependencies_c: public search_visitor_c {
+
+  private:
+    /* The level of detail that the user wants us to display error messages. */
+    #define error_level_default (1)
+    #define error_level_nagging (4)
+    unsigned int    current_display_error_level;
+    int             error_count;
+    bool            warning_found;
+    library_c      *new_tree;
+    int             cycle_count; // main algorithm runs in a loop. The nuber of the current cycle...
+    // NOTE: we need two lists in order to correctly handle overloaded functions
+    identifiers_symbtable_t      declared_identifiers; // list of identifiers already declared by the symbols in the new tree
+    std::set <symbol_c *>        inserted_symbols;     // list of symbols already inserted in the new tree 
+    symbol_c       *current_code_generation_pragma;    // points to any currently 'active' enable_code_generation_pragma_c
+    find_forward_dependencies_c    *find_forward_dependencies;  
+
+  public:
+     remove_forward_dependencies_c(void);
+    ~remove_forward_dependencies_c(void);
+    library_c *create_new_tree(symbol_c *old_tree);  // create a new tree with POUs ordered so it does not contain forward dependencies...
+    int        get_error_count(void);
+
+  private:
+    void *handle_library_symbol(symbol_c *symbol, symbol_c *name, symbol_c *search1, symbol_c *search2 = NULL, symbol_c *search3 = NULL);
+    void  print_circ_error(library_c *symbol);
+
+    /***************************/
+    /* B 0 - Programming Model */
+    /***************************/
+    void *visit(library_c *symbol);
+    /**************************************/
+    /* B.1.5 - Program organization units */
+    /**************************************/
+    void *visit(function_declaration_c *symbol);
+    void *visit(function_block_declaration_c *symbol);
+    void *visit(program_declaration_c *symbol);
+    /********************************/
+    /* B 1.7 Configuration elements */
+    /********************************/
+    void *visit(configuration_declaration_c *symbol);
+    /********************/
+    /* 2.1.6 - Pragmas  */
+    /********************/
+    void *visit(disable_code_generation_pragma_c *symbol);
+    void *visit(enable_code_generation_pragma_c *symbol);
+    void *visit(pragma_c *symbol);
+
+};   /* class remove_forward_dependencies_c */
+
+
+