Remove parsert::clear and all of its overrides

Re-use of parsers should no longer be necessary now that they aren't
objects of static lifetime anymore. Consequently, there is no need to
"clear," and instead only a subset of the instructions is required in
constructors.

Author: tautschnig

src/ansi-c/ansi_c_parser.h

@@ -43,24 +43,6 @@ class ansi_c_parsert:public parsert
 
   bool parse() override;
 
-  void clear() override
-  {
-    parsert::clear();
-    parse_tree.clear();
-
-    // scanner state
-    tag_following=false;
-    asm_block_following=false;
-    parenthesis_counter=0;
-    string_literal.clear();
-    pragma_pack.clear();
-    pragma_cprover_stack.clear();
-
-    // set up global scope
-    scopes.clear();
-    scopes.push_back(scopet());
-  }
-
   // internal state of the scanner
   bool tag_following;
   bool asm_block_following;

src/assembler/assembler_parser.h

@@ -42,12 +42,6 @@ class assembler_parsert:public parsert
   }
 
   bool parse() override;
-
-  void clear() override
-  {
-    parsert::clear();
-    instructions.clear();
-  }
 };
 
 #endif // CPROVER_ASSEMBLER_ASSEMBLER_PARSER_H

src/cpp/cpp_language.cpp

@@ -112,9 +112,6 @@ bool cpp_languaget::parse(
   // save result
   cpp_parse_tree.swap(cpp_parser.parse_tree);
 
-  // save some memory
-  cpp_parser.clear();
-
   return result;
 }
 
@@ -260,9 +257,6 @@ bool cpp_languaget::to_expr(
     result = cpp_typecheck(expr, message_handler, ns);
   }
 
-  // save some memory
-  cpp_parser.clear();
-
   return result;
 }
 

src/cpp/cpp_parser.h

@@ -28,14 +28,6 @@ class cpp_parsert:public parsert
 
   virtual bool parse() override;
 
-  virtual void clear() override
-  {
-    parsert::clear();
-    parse_tree.clear();
-    token_buffer.clear();
-    asm_block_following=false;
-  }
-
   explicit cpp_parsert(message_handlert &message_handler)
     : parsert(message_handler),
       mode(configt::ansi_ct::flavourt::ANSI),

src/json/json_parser.cpp

@@ -41,9 +41,6 @@ bool parse_json(
   if(json_parser.stack.size()==1)
     dest.swap(json_parser.stack.top());
 
-  // save some memory
-  json_parser.clear();
-
   return result;
 }
 

src/json/json_parser.h

@@ -41,11 +41,6 @@ class json_parsert:public parsert
     dest.swap(stack.top());
     stack.pop();
   }
-
-  virtual void clear() override
-  {
-    stack=stackt();
-  }
 };
 
 // 'do it all' functions

src/statement-list/statement_list_parser.cpp

@@ -352,12 +352,6 @@ bool statement_list_parsert::parse()
   return parse_fail;
 }
 
-void statement_list_parsert::clear()
-{
-  parsert::clear();
-  parse_tree.clear();
-}
-
 void statement_list_parsert::print_tree(std::ostream &out) const
 {
   output_parse_tree(out, parse_tree);

src/statement-list/statement_list_parser.h

@@ -74,10 +74,6 @@ class statement_list_parsert : public parsert
   /// \param other: Parse tree which should be used in the swap operation.
   void swap_tree(statement_list_parse_treet &other);
 
-  /// Removes all functions and function blocks from the parse tree and
-  /// clears the internal state of the parser.
-  void clear() override;
-
 private:
   /// Tree that is being filled by the parsing process.
   statement_list_parse_treet parse_tree;

src/util/parser.h

@@ -30,23 +30,20 @@ class parsert
 
   std::vector<exprt> stack;
 
-  virtual void clear()
+  DEPRECATED(SINCE(2023, 12, 20, "use parsert(message_handler) instead"))
+  parsert() : in(nullptr), line_no(0), previous_line_no(0), column(1)
   {
-    line_no=0;
-    previous_line_no=0;
-    column=1;
-    stack.clear();
-    source_location.clear();
-    last_line.clear();
   }
 
-  DEPRECATED(SINCE(2023, 12, 20, "use parsert(message_handler) instead"))
-  parsert():in(nullptr) { clear(); }
   explicit parsert(message_handlert &message_handler)
-    : in(nullptr), log(message_handler)
+    : in(nullptr),
+      log(message_handler),
+      line_no(0),
+      previous_line_no(0),
+      column(1)
   {
-    clear();
   }
+
   virtual ~parsert() { }
 
   // The following are for the benefit of the scanner

src/xmllang/xml_parser.h

@@ -50,17 +50,6 @@ class xml_parsert:public parsert
     stack.push_back(&current().elements.back());
   }
 
-  /// Clears the parser state. May be removed in future as there should not be a
-  /// need to re-use an existing parser object.
-  void clear() override
-  {
-    parse_tree.clear();
-    // set up stack
-    stack.clear();
-    stack.push_back(&parse_tree.element);
-    parsert::clear();
-  }
-
 protected:
   static int instance_count;
 };