use override in some central classes

Author: Daniel Kroening

src/ansi-c/ansi_c_parser.h

@@ -35,12 +35,12 @@ class ansi_c_parsert:public parsert
   {
   }
 
-  virtual bool parse()
+  virtual bool parse() override
   {
     return yyansi_cparse()!=0;
   }
 
-  virtual void clear()
+  virtual void clear() override 
   {
     parsert::clear();
     parse_tree.clear();

src/cbmc/cbmc_parse_options.h

@@ -63,8 +63,8 @@ class cbmc_parse_optionst:
   public language_uit
 {
 public:
-  virtual int doit();
-  virtual void help();
+  virtual int doit() override;
+  virtual void help() override;
 
   cbmc_parse_optionst(int argc, const char **argv);
   cbmc_parse_optionst(

src/cpp/cpp_parser.h

@@ -26,9 +26,9 @@ class cpp_parsert:public parsert
 public:
   cpp_parse_treet parse_tree;
 
-  virtual bool parse();
+  virtual bool parse() override;
 
-  virtual void clear()
+  virtual void clear() override
   {
     parsert::clear();
     parse_tree.clear();

src/goto-analyzer/goto_analyzer_parse_options.h

@@ -43,8 +43,8 @@ class goto_analyzer_parse_optionst:
   public language_uit
 {
 public:
-  virtual int doit();
-  virtual void help();
+  virtual int doit() override;
+  virtual void help() override;
 
   goto_analyzer_parse_optionst(int argc, const char **argv);
 

src/jsil/jsil_parser.h

@@ -20,12 +20,12 @@ class jsil_parsert:public parsert
 public:
   jsil_parse_treet parse_tree;
 
-  virtual bool parse()
+  virtual bool parse() override
   {
     return yyjsilparse()!=0;
   }
 
-  virtual void clear()
+  virtual void clear() override
   {
     parsert::clear();
     parse_tree.clear();

src/json/json_parser.cpp

@@ -36,7 +36,7 @@ bool parse_json(
   json_parser.in=∈
   json_parser.set_message_handler(message_handler);
 
-  bool result=yyjsonparse()!=0;
+  bool result=json_parser.parse();
 
   // save result
   if(json_parser.stack.size()==1)

src/json/json_parser.h

@@ -25,6 +25,11 @@ class json_parsert:public parsert
 
   inline jsont &top() { return stack.top(); }
 
+  virtual bool parse() override
+  {
+    return yyjsonparse()!=0;
+  }
+  
   inline void push(const jsont &x)
   {
     stack.push(x);
@@ -37,7 +42,7 @@ class json_parsert:public parsert
     stack.pop();
   }
 
-  virtual void clear()
+  virtual void clear() override
   {
     stack=stackt();
   }

src/util/parser.h

@@ -48,10 +48,7 @@ class parsert:public messaget
     return true;
   }
 
-  virtual bool parse()
-  {
-    return true;
-  }
+  virtual bool parse()=0;
 
   inline bool eof()
   {