--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/stage4/generate_c/decompose_var_instance_name.cc	Wed Oct 24 17:39:51 2007 +0200
@@ -0,0 +1,132 @@
+/*
+ * (c) 2003 Mario de Sousa
+ *
+ * Offered to the public under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2 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.
+ *
+ * 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 IL and ST compiler.
+ *
+ * Based on the
+ * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
+ *
+ */
+
+
+/* Decomposes a variable instance name into its constituents,
+ * example:
+ *    window.points[1].coordinate.x
+ *
+ *  will succesfully return
+ *        - window
+ *        - points
+ *        - coordinate
+ *        - x
+ * on succesive calls to decompose_var_instance_name_c::next_part()
+ */
+class decompose_var_instance_name_c: null_visitor_c {
+
+  private:
+    symbol_c *variable_name;
+    symbol_c *next_variable_name;
+    symbol_c *current_recursive_variable_name;
+    symbol_c *previously_returned_variable_name;
+
+  public:
+    decompose_var_instance_name_c(symbol_c *variable_instance_name) {
+      variable_name = variable_instance_name;
+      next_variable_name = NULL;
+      current_recursive_variable_name = NULL;
+      previously_returned_variable_name = NULL;
+    }
+
+  public:
+    symbol_c *next_part(void) {
+      /* We must always start from the top!
+       * See note in the structured_variable_c visitor
+       * to understand why...
+       */
+      symbol_c *res = (symbol_c *)variable_name->accept(*this);
+      next_variable_name = current_recursive_variable_name;
+
+      if (previously_returned_variable_name == res)
+        return NULL;
+      previously_returned_variable_name = res;
+      return res;
+    }
+
+  public:
+/*********************/
+/* B 1.4 - Variables */
+/*********************/
+    void *visit(symbolic_variable_c *symbol) {return (void *)(symbol->var_name);}
+
+/********************************************/
+/* B.1.4.1   Directly Represented Variables */
+/********************************************/
+    void *visit(direct_variable_c *symbol) {return (void *)symbol;}
+
+/*************************************/
+/* B.1.4.2   Multi-element Variables */
+/*************************************/
+/*  subscripted_variable '[' subscript_list ']' */
+// SYM_REF2(array_variable_c, subscripted_variable, subscript_list)
+    void *visit(array_variable_c *symbol) {
+      /* NOTE: the subscripted_variable may itself be a structure!,
+       * so we must recursevily visit!
+       */
+      return symbol->subscripted_variable->accept(*this);
+    }
+
+/*  record_variable '.' field_selector */
+/*  WARNING: input and/or output variables of function blocks
+ *           may be accessed as fields of a tructured variable!
+ *           Code handling a structured_variable_c must take
+ *           this into account!
+ */
+//SYM_REF2(structured_variable_c, record_variable, field_selector)
+    void *visit(structured_variable_c *symbol) {
+      /* NOTE: The following code will not work, as structured_variable_c
+       *       are grouped on the left, and not on the right!
+       *
+       *       example: window.origin.x
+       *       will result in
+       *       s1 = structured_variable_c("window, "origin");
+       *       s2 = structured_variable_c(s1, "x");
+       *       AND NOT
+       *       s1 = structured_variable_c("origin", "x");
+       *       s2 = structured_variable_c("window", s1);
+       *
+       *       as the following code assumes!!
+       *
+      current_variable_name = symbol->field_selector;
+      return symbol->record_variable->accept(*this);
+       */
+
+      /* The correct code, is therefore more complex... */
+      if (next_variable_name == symbol) {
+        /* NOTE: field_selector is always an identifier_c,
+	 * so we do not have to recursevily visit it again...
+	 * return (void *)symbol->field_selector->accept(*this);  -> NOT REQUIRED!!
+	 */
+	return (void *)symbol->field_selector;
+      }
+
+      current_recursive_variable_name = symbol;
+      return symbol->record_variable->accept(*this);
+    }
+};
+
+
+
+