use pure parser and reentrant lexer interfaces Making the Octave parser and lexer properly reentrant (and perhaps eventually thread safe as well) is still a work in progress. With the current set of changes the parser and lexer still use many global variables, so these changes alone do NOT make the Octave parser reentrant unless you take care to properly save and restore (typically with an unwind_protect object) relevant global values before and after calling the parser. Even if global variables are properly saved and restored, the parser will NOT be thread safe. * lex.ll: Use %option reentrant an %option bison-bridge. (yylval): Delete macro. (YY_EXTRA_TYPE, curr_lexer): New macros. Undefine curr_lexer (YY_FATAL_ERROR): Update decl for reentrant scanner. (lexical_feedback::reset): Update call to yyrestart for reentrant scanner interface. (lexical_feedback::fatal_error): Update call to yy_fatal_error for reentrant scanner interface. (lexical_feedback::text_yyinput): Update calls to yyinput and yyunput for reentrant scanner interface. (lexical_feedback::flex_yyleng): Use function interface to access yyleng. (lexical_feedback::flex_yytext): Use function interface to access yytext. (lexical_feedback::push_token, lexical_feedback::current_token): Use function interface to access yylval. * oct-parse.yy: Use %define api.pure, %parse-param, and %lex-param options. (curr_lexer): Define for syntax rules section. (scanner): New macro. * oct-parse.yy: Include oct-parse.h. (octave_lex): Declare. (yyerror): Update declaration for pure parser. * parse.h (octave_lex): Delete decl. * oct-parse.yy (octave_parser::run): Pass pointer to octave_parser object to octave_parse. * lex.ll (lexical_feedback::octave_read): Call fatal_error directly instead of using YY_FATAL_ERROR. * oct-parse.yy (parse_fcn_file): Pass line and column info for lexter to gobble_leading_whitespace. Access prep_for_script_file, prep_for_function_file, parsing_class_method, input_line_number, and current_input_column through curr_parser. * parse.h, oct-parse.yy (YY_BUFFER_STATE, create_buffer, current_buffer, switch_to_buffer, delete_buffer, clear_all_buffers): Delete. * toplev.cc (main_loop): Don't create new buffer for lexer. * input.cc (get_debug_input): Likewise. * oct-parse.yy (eval_string, parse_fcn_file): Likewise. * octave.cc (octave_initialize_interpreter): Likewise. * input.cc (get_debug_input): Likewise. * oct-parse.yy (eval_string, parse_fcn_file): Create parser as needed. * octave.cc (octave_initialize_interpreter): Likewise. * input.cc (get_debug_input): Likewise. * input.cc (input_even_hook): Allow function to run even if currently defining a function. * lex.h, lex.ll (curr_lexer): Delete global variable. * parse.h, oct-parse.yy (octave_parser::curr_lexer): New data member. (octave_parser::octave_parser): Create lexer here. (curr_parser): Delete global variable. * toplev.cc (main_loop): Don't protect global curr_lexer and curr_parser variables. * oct-parse.yy (eval_string, parse_fcn_file): Likewise. * input.cc (get_debug_input): Likewise. * lex.h, lex.ll (curr_lexer): Delete global variable. * parse.h, oct-parse.yy (CURR_LEXER): New temporary global. (octave_parser::octave_parser): Set global CURR_LEXER here. * toplev.cc (main_loop): Protect CURR_LEXER prior to constructing new parser object. * input.cc (get_debug_input): Likewise. * oct-parse.yy (eval_string, parse_fcn_file): Likewise. * lex.h, lex.ll (lexical_feedback::scanner): New data member. (lexical_feedback::init): Create it. Call yylex_set_extra to store pointer to lexical_feedback object in scanner data. (lexical_feedback::~lexical_feedback): Delete it. * lex.ll (YYG): New macro. (lexical_feedback::reset, lexical_feedback::prep_for_script_file, lexical_feedback::prep_for_function_file, lexical_feedback::process_comment, lexical_feedback::handle_close_bracket, lexical_feedback::handle_identifier, lexical_feedback::lexer_debug): Use it to access scanner data.

--- a/libinterp/interpfcn/input.cc
+++ b/libinterp/interpfcn/input.cc
@@ -667,29 +667,18 @@
 
       frame.protect_var (get_input_from_eval_string);
       get_input_from_eval_string = false;
-
-      YY_BUFFER_STATE old_buf = current_buffer ();
-      YY_BUFFER_STATE new_buf = create_buffer (get_input_from_stdin ());
-
-      // FIXME: are these safe?
-      frame.add_fcn (switch_to_buffer, old_buf);
-      frame.add_fcn (delete_buffer, new_buf);
-
-      switch_to_buffer (new_buf);
     }
 
-  frame.protect_var (curr_lexer);
-  curr_lexer = new lexical_feedback ();
-  frame.add_fcn (lexical_feedback::cleanup, curr_lexer);
-
-  frame.protect_var (curr_parser);
-  curr_parser = new octave_parser ();
-  frame.add_fcn (octave_parser::cleanup, curr_parser);
-
   while (Vdebugging)
     {
       unwind_protect middle_frame;
 
+      // octave_parser constructor sets this for us.
+      middle_frame.protect_var (CURR_LEXER);
+
+      octave_parser *curr_parser = new octave_parser ();
+      middle_frame.add_fcn (octave_parser::cleanup, curr_parser);
+
       reset_error_handler ();
 
       curr_parser->reset ();
@@ -1199,33 +1188,28 @@
 static int
 input_event_hook (void)
 {
-  if (! curr_lexer->defining_func)
-    {
-      hook_fcn_map_type::iterator p = hook_fcn_map.begin ();
+  hook_fcn_map_type::iterator p = hook_fcn_map.begin ();
 
-      while (p != hook_fcn_map.end ())
-        {
-          std::string hook_fcn = p->first;
-          octave_value user_data = p->second;
+  while (p != hook_fcn_map.end ())
+    {
+      std::string hook_fcn = p->first;
+      octave_value user_data = p->second;
 
-          hook_fcn_map_type::iterator q = p++;
+      hook_fcn_map_type::iterator q = p++;
 
-          if (is_valid_function (hook_fcn))
-            {
-              if (user_data.is_defined ())
-                feval (hook_fcn, user_data, 0);
-              else
-                feval (hook_fcn, octave_value_list (), 0);
-            }
+      if (is_valid_function (hook_fcn))
+        {
+          if (user_data.is_defined ())
+            feval (hook_fcn, user_data, 0);
           else
-            hook_fcn_map.erase (q);
+            feval (hook_fcn, octave_value_list (), 0);
         }
-
-      if (hook_fcn_map.empty ())
-        command_editor::remove_event_hook (input_event_hook);
+      else
+        hook_fcn_map.erase (q);
     }
 
-  return 0;
+  if (hook_fcn_map.empty ())
+    command_editor::remove_event_hook (input_event_hook);
 }
 
 DEFUN (add_input_event_hook, args, ,