C++-fy struct interp/cli_interp/tui_interp/mi_interp

- The interp->data field disappears, since we can put data in the
  interpreter directly now.  The "init" method remains in place, but
  it now returns void.

- A few places check if the interpreter method is NULL before calling
  it, and also check whether the method returns true/false.  For some
  of those methods, all current implementations always return true.
  In those cases, this commit makes the C++-fied method return void
  instead and cleans up the callers.

Tested on x86_64 Fedora 23.

gdb/ChangeLog:
2017-02-03  Pedro Alves  <palves@redhat.com>

	* cli/cli-interp.c (cli_interp_base::cli_interp_base)
	(cli_interp_base::~cli_interp_base): New.
	(cli_interp): New struct.
	(as_cli_interp): Cast the interp itself to cli_interp.
	(cli_interpreter_pre_command_loop): Rename to ...
	(cli_interp_base::pre_command_loop): ... this.  Remove 'self'
	parameter.
	(cli_interpreter_init): Rename to ...
	(cli_interp::init): ... this.  Remove 'self' parameter.  Use
	boolean.  Make extern.
	(cli_interpreter_resume): Rename to ...
	(cli_interp::resume): ... this.  Remove 'data' parameter.  Make
	extern.
	(cli_interpreter_suspend): Rename to ...
	(cli_interp::suspend): ... this.  Remove 'data' parameter.  Make
	extern.
	(cli_interpreter_exec): Rename to ...
	(cli_interp::exec): ... this.  Remove 'data' parameter.  Make
	extern.
	(cli_interpreter_supports_command_editing): Rename to ...
	(cli_interp_base::supports_command_editing): ... this.  Remove
	'interp' parameter.  Make extern.
	(cli_ui_out): Rename to ...
	(cli_interp::interp_ui_out): ... this.  Remove 'interp' parameter.
	Make extern.
	(cli_set_logging): Rename to ...
	(cli_interp_base::set_logging): ... this.  Remove 'interp'
	parameter.  Make extern.
	(cli_interp_procs): Delete.
	(cli_interp_factory): Adjust to use "new".
	* cli/cli-interp.h: Include "interps.h".
	(struct cli_interp_base): New struct.
	* interps.c (struct interp): Delete.  Fields moved to interps.h.
	(interp_new): Delete.
	(interp::interp, interp::~interp): New.
	(interp_set): Use bool, and return void.  Assume the interpreter
	has suspend, init and resume methods, and that the all return
	void.
	(set_top_level_interpreter): interp_set returns void.
	(interp_ui_out): Adapt.
	(current_interp_set_logging): Adapt.
	(interp_data): Delete.
	(interp_pre_command_loop, interp_supports_command_editing): Adapt.
	(interp_exec): Adapt.
	(top_level_interpreter_data): Delete.
	* interps.h (interp_init_ftype, interp_resume_ftype)
	(interp_suspend_ftype, interp_exec_ftype)
	(interp_pre_command_loop_ftype, interp_ui_out_ftype): Delete.
	(class interp): New.
	(interp_new): Delete.
	(interp_set): Now returns void.  Use bool.
	(interp_data, top_level_interpreter_data): Delete.
	* mi/mi-common.h: Include interps.h.
	(class mi_interp): Inherit from interp.  Define a ctor.  Declare
	init, resume, suspect, exec, interp_ui_out, set_logging and
	pre_command_loop methods.
	* mi/mi-interp.c (as_mi_interp): Cast the interp itself.
	(mi_interpreter_init): Rename to ...
	(mi_interp::init): ... this.  Remove the 'interp' parameter, use
	bool, return void and make extern.  Adjust.
	(mi_interpreter_resume): ... Rename to ...
	(mi_interp::resume): ... this.  Remove the 'data' parameter,
	return void and make extern.  Adjust.
	(mi_interpreter_suspend): ... Rename to ...
	(mi_interp::suspend): ... this.  Remove the 'data' parameter,
	return void and make extern.  Adjust.
	(mi_interpreter_exec): ... Rename to ...
	(mi_interp::exec): ... this.  Remove the 'data' parameter and make
	extern.  Adjust.
	(mi_interpreter_pre_command_loop): ... Rename to ...
	(mi_interp::pre_command_loop): ... this.  Remove the 'self'
	parameter and make extern.
	(mi_on_normal_stop_1): Adjust.
	(mi_ui_out): Rename to ...
	(mi_interp::interp_ui_out): ... this.  Remove the 'interp'
	parameter and make extern.  Adjust.
	(mi_set_logging): Rename to ...
	(mi_interp::set_logging): ... this.  Remove the 'interp'
	parameter and make extern.  Adjust.
	(mi_interp_procs): Delete.
	(mi_interp_factory): Adjust to use 'new'.
	* mi/mi-main.c (mi_cmd_gdb_exit, captured_mi_execute_command)
	(mi_print_exception, mi_execute_command, mi_load_progress):
	Adjust.
	* tui/tui-interp.c (tui_interp): New class.
	(as_tui_interp): Return a tui_interp pointer.
	(tui_on_normal_stop, tui_on_signal_received)
	(tui_on_end_stepping_range, tui_on_signal_exited, tui_on_exited)
	(tui_on_no_history, tui_on_user_selected_context_changed): Adjust
	to use interp::interp_ui_out.
	(tui_init): Rename to ...
	(tui_interp::init): ... this.  Remove the 'self' parameter, use
	bool, return void and make extern.  Adjust.
	(tui_resume): Rename to ...
	(tui_interp::resume): ... this.  Remove the 'data' parameter,
	return void and make extern.  Adjust.
	(tui_suspend): Rename to ...
	(tui_interp::suspend): ... this.  Remove the 'data' parameter,
	return void and make extern.  Adjust.
	(tui_ui_out): Rename to ...
	(tui_interp::interp_ui_out): ... this.  Remove the 'self'
	parameter, and make extern.  Adjust.
	(tui_exec): Rename to ...
	(tui_interp::exec): ... this.  Remove the 'data' parameter and
	make extern.
	(tui_interp_procs): Delete.
	(tui_interp_factory): Use "new".

9 files changed, 304 insertions, 271 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 2f5ba2f..2016c81 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,113 @@
+2017-02-03  Pedro Alves  <palves@redhat.com>
+
+	* cli/cli-interp.c (cli_interp_base::cli_interp_base)
+	(cli_interp_base::~cli_interp_base): New.
+	(cli_interp): New struct.
+	(as_cli_interp): Cast the interp itself to cli_interp.
+	(cli_interpreter_pre_command_loop): Rename to ...
+	(cli_interp_base::pre_command_loop): ... this.  Remove 'self'
+	parameter.
+	(cli_interpreter_init): Rename to ...
+	(cli_interp::init): ... this.  Remove 'self' parameter.  Use
+	boolean.  Make extern.
+	(cli_interpreter_resume): Rename to ...
+	(cli_interp::resume): ... this.  Remove 'data' parameter.  Make
+	extern.
+	(cli_interpreter_suspend): Rename to ...
+	(cli_interp::suspend): ... this.  Remove 'data' parameter.  Make
+	extern.
+	(cli_interpreter_exec): Rename to ...
+	(cli_interp::exec): ... this.  Remove 'data' parameter.  Make
+	extern.
+	(cli_interpreter_supports_command_editing): Rename to ...
+	(cli_interp_base::supports_command_editing): ... this.  Remove
+	'interp' parameter.  Make extern.
+	(cli_ui_out): Rename to ...
+	(cli_interp::interp_ui_out): ... this.  Remove 'interp' parameter.
+	Make extern.
+	(cli_set_logging): Rename to ...
+	(cli_interp_base::set_logging): ... this.  Remove 'interp'
+	parameter.  Make extern.
+	(cli_interp_procs): Delete.
+	(cli_interp_factory): Adjust to use "new".
+	* cli/cli-interp.h: Include "interps.h".
+	(struct cli_interp_base): New struct.
+	* interps.c (struct interp): Delete.  Fields moved to interps.h.
+	(interp_new): Delete.
+	(interp::interp, interp::~interp): New.
+	(interp_set): Use bool, and return void.  Assume the interpreter
+	has suspend, init and resume methods, and that the all return
+	void.
+	(set_top_level_interpreter): interp_set returns void.
+	(interp_ui_out): Adapt.
+	(current_interp_set_logging): Adapt.
+	(interp_data): Delete.
+	(interp_pre_command_loop, interp_supports_command_editing): Adapt.
+	(interp_exec): Adapt.
+	(top_level_interpreter_data): Delete.
+	* interps.h (interp_init_ftype, interp_resume_ftype)
+	(interp_suspend_ftype, interp_exec_ftype)
+	(interp_pre_command_loop_ftype, interp_ui_out_ftype): Delete.
+	(class interp): New.
+	(interp_new): Delete.
+	(interp_set): Now returns void.  Use bool.
+	(interp_data, top_level_interpreter_data): Delete.
+	* mi/mi-common.h: Include interps.h.
+	(class mi_interp): Inherit from interp.  Define a ctor.  Declare
+	init, resume, suspect, exec, interp_ui_out, set_logging and
+	pre_command_loop methods.
+	* mi/mi-interp.c (as_mi_interp): Cast the interp itself.
+	(mi_interpreter_init): Rename to ...
+	(mi_interp::init): ... this.  Remove the 'interp' parameter, use
+	bool, return void and make extern.  Adjust.
+	(mi_interpreter_resume): ... Rename to ...
+	(mi_interp::resume): ... this.  Remove the 'data' parameter,
+	return void and make extern.  Adjust.
+	(mi_interpreter_suspend): ... Rename to ...
+	(mi_interp::suspend): ... this.  Remove the 'data' parameter,
+	return void and make extern.  Adjust.
+	(mi_interpreter_exec): ... Rename to ...
+	(mi_interp::exec): ... this.  Remove the 'data' parameter and make
+	extern.  Adjust.
+	(mi_interpreter_pre_command_loop): ... Rename to ...
+	(mi_interp::pre_command_loop): ... this.  Remove the 'self'
+	parameter and make extern.
+	(mi_on_normal_stop_1): Adjust.
+	(mi_ui_out): Rename to ...
+	(mi_interp::interp_ui_out): ... this.  Remove the 'interp'
+	parameter and make extern.  Adjust.
+	(mi_set_logging): Rename to ...
+	(mi_interp::set_logging): ... this.  Remove the 'interp'
+	parameter and make extern.  Adjust.
+	(mi_interp_procs): Delete.
+	(mi_interp_factory): Adjust to use 'new'.
+	* mi/mi-main.c (mi_cmd_gdb_exit, captured_mi_execute_command)
+	(mi_print_exception, mi_execute_command, mi_load_progress):
+	Adjust.
+	* tui/tui-interp.c (tui_interp): New class.
+	(as_tui_interp): Return a tui_interp pointer.
+	(tui_on_normal_stop, tui_on_signal_received)
+	(tui_on_end_stepping_range, tui_on_signal_exited, tui_on_exited)
+	(tui_on_no_history, tui_on_user_selected_context_changed): Adjust
+	to use interp::interp_ui_out.
+	(tui_init): Rename to ...
+	(tui_interp::init): ... this.  Remove the 'self' parameter, use
+	bool, return void and make extern.  Adjust.
+	(tui_resume): Rename to ...
+	(tui_interp::resume): ... this.  Remove the 'data' parameter,
+	return void and make extern.  Adjust.
+	(tui_suspend): Rename to ...
+	(tui_interp::suspend): ... this.  Remove the 'data' parameter,
+	return void and make extern.  Adjust.
+	(tui_ui_out): Rename to ...
+	(tui_interp::interp_ui_out): ... this.  Remove the 'self'
+	parameter, and make extern.  Adjust.
+	(tui_exec): Rename to ...
+	(tui_interp::exec): ... this.  Remove the 'data' parameter and
+	make extern.
+	(tui_interp_procs): Delete.
+	(tui_interp_factory): Use "new".
+
 2017-02-02  Tom Tromey  <tom@tromey.com>
 
 	* rust-exp.y (ends_raw_string, space_then_number)
diff --git a/gdb/cli/cli-interp.c b/gdb/cli/cli-interp.c
index e0327f6..8712c75 100644
--- a/gdb/cli/cli-interp.c
+++ b/gdb/cli/cli-interp.c
@@ -30,13 +30,37 @@
 #include "gdbthread.h"
 #include "thread-fsm.h"
 
+cli_interp_base::cli_interp_base (const char *name)
+  : interp (name)
+{}
+
+cli_interp_base::~cli_interp_base ()
+{}
+
 /* The console interpreter.  */
-struct cli_interp
+
+class cli_interp final : public cli_interp_base
 {
+ public:
+  explicit cli_interp (const char *name);
+
+  void init (bool top_level) override;
+  void resume () override;
+  void suspend () override;
+  gdb_exception exec (const char *command_str) override;
+  ui_out *interp_ui_out () override;
+
   /* The ui_out for the console interpreter.  */
   cli_ui_out *cli_uiout;
 };
 
+cli_interp::cli_interp (const char *name)
+  : cli_interp_base (name)
+{
+  /* Create a default uiout builder for the CLI.  */
+  this->cli_uiout = cli_out_new (gdb_stdout);
+}
+
 /* Suppress notification struct.  */
 struct cli_suppress_notification cli_suppress_notification =
   {
@@ -50,7 +74,7 @@ static struct cli_interp *
 as_cli_interp (struct interp *interp)
 {
   if (strcmp (interp_name (interp), INTERP_CONSOLE) == 0)
-    return (struct cli_interp *) interp_data (interp);
+    return (struct cli_interp *) interp;
   return NULL;
 }
 
@@ -255,24 +279,23 @@ cli_on_user_selected_context_changed (user_selected_what selection)
 /* pre_command_loop implementation.  */
 
 void
-cli_interpreter_pre_command_loop (struct interp *self)
+cli_interp_base::pre_command_loop ()
 {
   display_gdb_prompt (0);
 }
 
 /* These implement the cli out interpreter: */
 
-static void *
-cli_interpreter_init (struct interp *self, int top_level)
+void
+cli_interp::init (bool top_level)
 {
-  return interp_data (self);
 }
 
-static int
-cli_interpreter_resume (void *data)
+void
+cli_interp::resume ()
 {
   struct ui *ui = current_ui;
-  struct cli_interp *cli = (struct cli_interp *) data;
+  struct cli_interp *cli = this;
   struct ui_file *stream;
 
   /*sync_execution = 1; */
@@ -294,21 +317,18 @@ cli_interpreter_resume (void *data)
 
   if (stream != NULL)
     cli->cli_uiout->set_stream (gdb_stdout);
-
-  return 1;
 }
 
-static int
-cli_interpreter_suspend (void *data)
+void
+cli_interp::suspend ()
 {
   gdb_disable_readline ();
-  return 1;
 }
 
-static struct gdb_exception
-cli_interpreter_exec (void *data, const char *command_str)
+gdb_exception
+cli_interp::exec (const char *command_str)
 {
-  struct cli_interp *cli = (struct cli_interp *) data;
+  struct cli_interp *cli = this;
   struct ui_file *old_stream;
   struct gdb_exception result;
 
@@ -330,10 +350,10 @@ cli_interpreter_exec (void *data, const char *command_str)
   return result;
 }
 
-int
-cli_interpreter_supports_command_editing (struct interp *interp)
+bool
+cli_interp_base::supports_command_editing ()
 {
-  return 1;
+  return true;
 }
 
 static struct gdb_exception
@@ -365,10 +385,10 @@ safe_execute_command (struct ui_out *command_uiout, char *command, int from_tty)
   return e;
 }
 
-static struct ui_out *
-cli_ui_out (struct interp *self)
+ui_out *
+cli_interp::interp_ui_out ()
 {
-  struct cli_interp *cli = (struct cli_interp *) interp_data (self);
+  struct cli_interp *cli = (struct cli_interp *) this;
 
   return cli->cli_uiout;
 }
@@ -388,8 +408,7 @@ static saved_output_files saved_output;
 /* See cli-interp.h.  */
 
 void
-cli_set_logging (struct interp *interp,
-		 ui_file_up logfile, bool logging_redirect)
+cli_interp_base::set_logging (ui_file_up logfile, bool logging_redirect)
 {
   if (logfile != NULL)
     {
@@ -430,30 +449,12 @@ cli_set_logging (struct interp *interp,
     }
 }
 
-/* The CLI interpreter's vtable.  */
-
-static const struct interp_procs cli_interp_procs = {
-  cli_interpreter_init,		/* init_proc */
-  cli_interpreter_resume,	/* resume_proc */
-  cli_interpreter_suspend,	/* suspend_proc */
-  cli_interpreter_exec,		/* exec_proc */
-  cli_ui_out,			/* ui_out_proc */
-  cli_set_logging,		/* set_logging_proc */
-  cli_interpreter_pre_command_loop, /* pre_command_loop_proc */
-  cli_interpreter_supports_command_editing, /* supports_command_editing_proc */
-};
-
 /* Factory for CLI interpreters.  */
 
 static struct interp *
 cli_interp_factory (const char *name)
 {
-  struct cli_interp *cli = XNEW (struct cli_interp);
-
-  /* Create a default uiout builder for the CLI.  */
-  cli->cli_uiout = cli_out_new (gdb_stdout);
-
-  return interp_new (name, &cli_interp_procs, cli);
+  return new cli_interp (name);
 }
 
 /* Standard gdb initialization hook.  */
diff --git a/gdb/cli/cli-interp.h b/gdb/cli/cli-interp.h
index f93548c..de9da83 100644
--- a/gdb/cli/cli-interp.h
+++ b/gdb/cli/cli-interp.h
@@ -18,7 +18,20 @@
 #ifndef CLI_INTERP_H
 #define CLI_INTERP_H 1
 
-struct interp;
+#include "interps.h"
+
+/* A console-like interpreter.  Implements functionality common to the
+   CLI and the TUI.  */
+class cli_interp_base : public interp
+{
+public:
+  explicit cli_interp_base (const char *name);
+  virtual ~cli_interp_base () = 0;
+
+  void set_logging (ui_file_up logfile, bool logging_redirect) override;
+  void pre_command_loop () override;
+  bool supports_command_editing () override;
+};
 
 /* Make the output ui_file to use when logging is enabled.
    CURR_OUTPUT is the stream where output is currently being sent to
diff --git a/gdb/interps.c b/gdb/interps.c
index 06e7ccf..d31d53b 100644
--- a/gdb/interps.c
+++ b/gdb/interps.c
@@ -72,28 +72,6 @@ get_current_interp_info (void)
   return get_interp_info (current_ui);
 }
 
-struct interp
-{
-  /* This is the name in "-i=" and set interpreter.  */
-  const char *name;
-
-  /* Interpreters are stored in a linked list, this is the next
-     one...  */
-  struct interp *next;
-
-  /* This is a cookie that an instance of the interpreter can use.
-     This is a bit confused right now as the exact initialization
-     sequence for it, and how it relates to the interpreter's uiout
-     object is a bit confused.  */
-  void *data;
-
-  /* Has the init_proc been run?  */
-  int inited;
-
-  const struct interp_procs *procs;
-  int quiet_p;
-};
-
 /* The magic initialization routine for this module.  */
 
 void _initialize_interpreter (void);
@@ -101,25 +79,16 @@ void _initialize_interpreter (void);
 static struct interp *interp_lookup_existing (struct ui *ui,
 					      const char *name);
 
-/* interp_new - This allocates space for a new interpreter,
-   fills the fields from the inputs, and returns a pointer to the
-   interpreter.  */
-struct interp *
-interp_new (const char *name, const struct interp_procs *procs, void *data)
+interp::interp (const char *name)
 {
-  struct interp *new_interp;
-
-  new_interp = XNEW (struct interp);
-
-  new_interp->name = xstrdup (name);
-  new_interp->data = data;
-  new_interp->quiet_p = 0;
-  new_interp->procs = procs;
-  new_interp->inited = 0;
-
-  return new_interp;
+  this->name = xstrdup (name);
+  this->quiet_p = false;
+  this->inited = false;
 }
 
+interp::~interp ()
+{}
+
 /* An interpreter factory.  Maps an interpreter name to the factory
    function that instantiates an interpreter by that name.  */
 
@@ -177,11 +146,7 @@ interp_add (struct ui *ui, struct interp *interp)
 }
 
 /* This sets the current interpreter to be INTERP.  If INTERP has not
-   been initialized, then this will also run the init proc.  If the
-   init proc is successful, return 1, if it fails, set the old
-   interpreter back in place and return 0.  If we can't restore the
-   old interpreter, then raise an internal error, since we are in
-   pretty bad shape at this point.
+   been initialized, then this will also run the init method.
 
    The TOP_LEVEL parameter tells if this new interpreter is
    the top-level one.  The top-level is what is requested
@@ -190,8 +155,9 @@ interp_add (struct ui *ui, struct interp *interp)
    MI is the top-level interpreter, then it will always report
    events such as target stops and new thread creation, even if they
    are caused by CLI commands.  */
-int
-interp_set (struct interp *interp, int top_level)
+
+void
+interp_set (struct interp *interp, bool top_level)
 {
   struct ui_interp_info *ui_interp = get_current_interp_info ();
   struct interp *old_interp = ui_interp->current_interpreter;
@@ -206,12 +172,7 @@ interp_set (struct interp *interp, int top_level)
   if (old_interp != NULL)
     {
       current_uiout->flush ();
-      if (old_interp->procs->suspend_proc
-	  && !old_interp->procs->suspend_proc (old_interp->data))
-	{
-	  error (_("Could not suspend interpreter \"%s\"."),
-		 old_interp->name);
-	}
+      old_interp->suspend ();
     }
   else
     {
@@ -232,32 +193,20 @@ interp_set (struct interp *interp, int top_level)
       interpreter_p = xstrdup (interp->name);
     }
 
-  /* Run the init proc.  If it fails, try to restore the old interp.  */
-
+  /* Run the init proc.  */
   if (!interp->inited)
     {
-      if (interp->procs->init_proc != NULL)
-	{
-	  interp->data = interp->procs->init_proc (interp, top_level);
-	}
-      interp->inited = 1;
+      interp->init (top_level);
+      interp->inited = true;
     }
 
   /* Do this only after the interpreter is initialized.  */
-  current_uiout = interp->procs->ui_out_proc (interp);
+  current_uiout = interp->interp_ui_out ();
 
   /* Clear out any installed interpreter hooks/event handlers.  */
   clear_interpreter_hooks ();
 
-  if (interp->procs->resume_proc != NULL
-      && (!interp->procs->resume_proc (interp->data)))
-    {
-      if (old_interp == NULL || !interp_set (old_interp, 0))
-	internal_error (__FILE__, __LINE__,
-			_("Failed to initialize new interp \"%s\" %s"),
-			interp->name, "and could not restore old interp!\n");
-      return 0;
-    }
+  interp->resume ();
 
   if (!first_time && !interp_quiet_p (interp))
     {
@@ -265,8 +214,6 @@ interp_set (struct interp *interp, int top_level)
 		 "Switching to interpreter \"%.24s\".\n", interp->name);
       current_uiout->text (buffer);
     }
-
-  return 1;
 }
 
 /* Look up the interpreter for NAME.  If no such interpreter exists,
@@ -330,8 +277,7 @@ set_top_level_interpreter (const char *name)
   if (interp == NULL)
     error (_("Interpreter `%s' unrecognized"), name);
   /* Install it.  */
-  if (!interp_set (interp, 1))
-    error (_("Interpreter `%s' failed to initialize."), name);
+  interp_set (interp, true);
 }
 
 /* Returns the current interpreter.  */
@@ -343,7 +289,7 @@ interp_ui_out (struct interp *interp)
 
   if (interp == NULL)
     interp = ui_interp->current_interpreter;
-  return interp->procs->ui_out_proc (interp);
+  return interp->interp_ui_out ();
 }
 
 void
@@ -353,8 +299,7 @@ current_interp_set_logging (ui_file_up logfile,
   struct ui_interp_info *ui_interp = get_current_interp_info ();
   struct interp *interp = ui_interp->current_interpreter;
 
-  return interp->procs->set_logging_proc (interp, std::move (logfile),
-					  logging_redirect);
+  return interp->set_logging (std::move (logfile), logging_redirect);
 }
 
 /* Temporarily overrides the current interpreter.  */
@@ -370,14 +315,6 @@ interp_set_temp (const char *name)
   return old_interp;
 }
 
-/* Returns the interpreter's cookie.  */
-
-void *
-interp_data (struct interp *interp)
-{
-  return interp->data;
-}
-
 /* Returns the interpreter's name.  */
 
 const char *
@@ -427,8 +364,7 @@ interp_pre_command_loop (struct interp *interp)
 {
   gdb_assert (interp != NULL);
 
-  if (interp->procs->pre_command_loop_proc != NULL)
-    interp->procs->pre_command_loop_proc (interp);
+  interp->pre_command_loop ();
 }
 
 /* See interp.h  */
@@ -436,9 +372,7 @@ interp_pre_command_loop (struct interp *interp)
 int
 interp_supports_command_editing (struct interp *interp)
 {
-  if (interp->procs->supports_command_editing_proc != NULL)
-    return interp->procs->supports_command_editing_proc (interp);
-  return 0;
+  return interp->supports_command_editing ();
 }
 
 int
@@ -472,13 +406,11 @@ interp_exec (struct interp *interp, const char *command_str)
   struct gdb_exception ex;
   struct interp *save_command_interp;
 
-  gdb_assert (interp->procs->exec_proc != NULL);
-
   /* See `command_interp' for why we do this.  */
   save_command_interp = ui_interp->command_interpreter;
   ui_interp->command_interpreter = interp;
 
-  ex = interp->procs->exec_proc (interp->data, command_str);
+  ex = interp->exec (command_str);
 
   ui_interp->command_interpreter = save_command_interp;
 
@@ -539,8 +471,7 @@ interpreter_exec_cmd (char *args, int from_tty)
   old_quiet = interp_set_quiet (old_interp, 1);
   use_quiet = interp_set_quiet (interp_to_use, 1);
 
-  if (!interp_set (interp_to_use, 0))
-    error (_("Could not switch to interpreter \"%s\"."), prules[0]);
+  interp_set (interp_to_use, false);
 
   for (i = 1; i < nrules; i++)
     {
@@ -612,16 +543,6 @@ top_level_interpreter (void)
   return ui_interp->top_level_interpreter;
 }
 
-void *
-top_level_interpreter_data (void)
-{
-  struct interp *interp;
-
-  interp = top_level_interpreter ();
-  gdb_assert (interp != NULL);
-  return interp->data;
-}
-
 /* See interps.h.  */
 
 struct interp *
diff --git a/gdb/interps.h b/gdb/interps.h
index ef2ceeb..e564980 100644
--- a/gdb/interps.h
+++ b/gdb/interps.h
@@ -41,53 +41,57 @@ extern struct gdb_exception interp_exec (struct interp *interp,
 					 const char *command);
 extern int interp_quiet_p (struct interp *interp);
 
-typedef void *(interp_init_ftype) (struct interp *self, int top_level);
-typedef int (interp_resume_ftype) (void *data);
-typedef int (interp_suspend_ftype) (void *data);
-typedef struct gdb_exception (interp_exec_ftype) (void *data,
-						  const char *command);
-typedef void (interp_pre_command_loop_ftype) (struct interp *self);
-typedef struct ui_out *(interp_ui_out_ftype) (struct interp *self);
+class interp
+{
+public:
+  explicit interp (const char *name);
+  virtual ~interp () = 0;
 
-typedef void (interp_set_logging_ftype) (struct interp *self,
-					 ui_file_up logfile,
-					 bool logging_redirect);
+  virtual void init (bool top_level)
+  {}
 
-typedef int (interp_supports_command_editing_ftype) (struct interp *self);
+  virtual void resume () = 0;
+  virtual void suspend () = 0;
 
-struct interp_procs
-{
-  interp_init_ftype *init_proc;
-  interp_resume_ftype *resume_proc;
-  interp_suspend_ftype *suspend_proc;
-  interp_exec_ftype *exec_proc;
+  virtual gdb_exception exec (const char *command) = 0;
 
   /* Returns the ui_out currently used to collect results for this
      interpreter.  It can be a formatter for stdout, as is the case
      for the console & mi outputs, or it might be a result
      formatter.  */
-  interp_ui_out_ftype *ui_out_proc;
+  virtual ui_out *interp_ui_out () = 0;
 
   /* Provides a hook for interpreters to do any additional
      setup/cleanup that they might need when logging is enabled or
      disabled.  */
-  interp_set_logging_ftype *set_logging_proc;
+  virtual void set_logging (ui_file_up logfile, bool logging_redirect) = 0;
 
   /* Called before starting an event loop, to give the interpreter a
      chance to e.g., print a prompt.  */
-  interp_pre_command_loop_ftype *pre_command_loop_proc;
+  virtual void pre_command_loop ()
+  {}
 
   /* Returns true if this interpreter supports using the readline
      library; false if it uses GDB's own simplified readline
      emulation.  */
-  interp_supports_command_editing_ftype *supports_command_editing_proc;
+  virtual bool supports_command_editing ()
+  { return false; }
+
+  /* This is the name in "-i=" and "set interpreter".  */
+  const char *name;
+
+  /* Interpreters are stored in a linked list, this is the next
+     one...  */
+  struct interp *next;
+
+  /* Has the init method been run?  */
+  bool inited;
+
+  bool quiet_p;
 };
 
-extern struct interp *interp_new (const char *name,
-				  const struct interp_procs *procs,
-				  void *data);
 extern void interp_add (struct ui *ui, struct interp *interp);
-extern int interp_set (struct interp *interp, int top_level);
+extern void interp_set (struct interp *interp, bool top_level);
 
 /* Look up the interpreter for NAME, creating one if none exists yet.
    If NAME is not a interpreter type previously registered with
@@ -101,7 +105,6 @@ extern struct interp *interp_lookup (struct ui *ui, const char *name);
 extern void set_top_level_interpreter (const char *name);
 
 extern struct ui_out *interp_ui_out (struct interp *interp);
-extern void *interp_data (struct interp *interp);
 extern const char *interp_name (struct interp *interp);
 extern struct interp *interp_set_temp (const char *name);
 
@@ -119,8 +122,7 @@ extern int current_interp_named_p (const char *name);
 extern void current_interp_set_logging (ui_file_up logfile,
 					bool logging_redirect);
 
-/* Returns opaque data associated with the top-level interpreter.  */
-extern void *top_level_interpreter_data (void);
+/* Returns the top-level interpreter.  */
 extern struct interp *top_level_interpreter (void);
 
 /* Return the current UI's current interpreter.  */
diff --git a/gdb/mi/mi-common.h b/gdb/mi/mi-common.h
index 9ee38b0..8fa9c9d 100644
--- a/gdb/mi/mi-common.h
+++ b/gdb/mi/mi-common.h
@@ -19,6 +19,8 @@
 #ifndef MI_COMMON_H
 #define MI_COMMON_H
 
+#include "interps.h"
+
 struct mi_console_file;
 
 /* Represents the reason why GDB is sending an asynchronous command to
@@ -50,8 +52,23 @@ enum async_reply_reason
 
 const char *async_reason_lookup (enum async_reply_reason reason);
 
-struct mi_interp
+/* An MI interpreter.  */
+
+class mi_interp final : public interp
 {
+public:
+  mi_interp (const char *name)
+    : interp (name)
+  {}
+
+  void init (bool top_level) override;
+  void resume () override;
+  void suspend () override;
+  gdb_exception exec (const char *command_str) override;
+  ui_out *interp_ui_out () override;
+  void set_logging (ui_file_up logfile, bool logging_redirect) override;
+  void pre_command_loop () override;
+
   /* MI's output channels */
   mi_console_file *out;
   mi_console_file *err;
diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
index aa76989..86340e4 100644
--- a/gdb/mi/mi-interp.c
+++ b/gdb/mi/mi-interp.c
@@ -108,14 +108,14 @@ static struct mi_interp *
 as_mi_interp (struct interp *interp)
 {
   if (interp_ui_out (interp)->is_mi_like_p ())
-    return (struct mi_interp *) interp_data (interp);
+    return (struct mi_interp *) interp;
   return NULL;
 }
 
-static void *
-mi_interpreter_init (struct interp *interp, int top_level)
+void
+mi_interp::init (bool top_level)
 {
-  struct mi_interp *mi = XNEW (struct mi_interp);
+  mi_interp *mi = this;
   const char *name;
   int mi_version;
 
@@ -132,7 +132,7 @@ mi_interpreter_init (struct interp *interp, int top_level)
   mi->targ = new mi_console_file (mi->raw_stdout, "@", '"');
   mi->event_channel = new mi_console_file (mi->raw_stdout, "=", 0);
 
-  name = interp_name (interp);
+  name = interp_name (this);
   /* INTERP_MI selects the most recent released version.  "mi2" was
      released as part of GDB 6.0.  */
   if (strcmp (name, INTERP_MI) == 0)
@@ -157,14 +157,12 @@ mi_interpreter_init (struct interp *interp, int top_level)
 	 up-front.  */
       iterate_over_inferiors (report_initial_inferior, mi);
     }
-
-  return mi;
 }
 
-static int
-mi_interpreter_resume (void *data)
+void
+mi_interp::resume ()
 {
-  struct mi_interp *mi = (struct mi_interp *) data;
+  struct mi_interp *mi = this;
   struct ui *ui = current_ui;
 
   /* As per hack note in mi_interpreter_init, swap in the output
@@ -188,19 +186,16 @@ mi_interpreter_resume (void *data)
   clear_interpreter_hooks ();
 
   deprecated_show_load_progress = mi_load_progress;
-
-  return 1;
 }
 
-static int
-mi_interpreter_suspend (void *data)
+void
+mi_interp::suspend ()
 {
   gdb_disable_readline ();
-  return 1;
 }
 
-static struct gdb_exception
-mi_interpreter_exec (void *data, const char *command)
+gdb_exception
+mi_interp::exec (const char *command)
 {
   mi_execute_command_wrapper (command);
   return exception_none;
@@ -327,10 +322,10 @@ mi_execute_command_input_handler (char *cmd)
     display_mi_prompt (mi);
 }
 
-static void
-mi_interpreter_pre_command_loop (struct interp *self)
+void
+mi_interp::pre_command_loop ()
 {
-  struct mi_interp *mi = (struct mi_interp *) interp_data (self);
+  struct mi_interp *mi = this;
 
   /* Turn off 8 bit strings in quoted output.  Any character with the
      high bit set is printed using C's octal format.  */
@@ -658,7 +653,7 @@ mi_on_normal_stop_1 (struct bpstats *bs, int print_frame)
      using cli interpreter, be sure to use MI uiout for output,
      not the current one.  */
   struct ui_out *mi_uiout = interp_ui_out (top_level_interpreter ());
-  struct mi_interp *mi = (struct mi_interp *) top_level_interpreter_data ();
+  struct mi_interp *mi = (struct mi_interp *) top_level_interpreter ();
 
   if (print_frame)
     {
@@ -1362,24 +1357,19 @@ report_initial_inferior (struct inferior *inf, void *closure)
   return 0;
 }
 
-static struct ui_out *
-mi_ui_out (struct interp *interp)
+ui_out *
+mi_interp::interp_ui_out ()
 {
-  struct mi_interp *mi = (struct mi_interp *) interp_data (interp);
-
-  return mi->mi_uiout;
+  return this->mi_uiout;
 }
 
 /* Do MI-specific logging actions; save raw_stdout, and change all
    the consoles to use the supplied ui-file(s).  */
 
-static void
-mi_set_logging (struct interp *interp,
-	        ui_file_up logfile, bool logging_redirect)
+void
+mi_interp::set_logging (ui_file_up logfile, bool logging_redirect)
 {
-  struct mi_interp *mi = (struct mi_interp *) interp_data (interp);
-
-  gdb_assert (mi != NULL);
+  struct mi_interp *mi = this;
 
   if (logfile != NULL)
     {
@@ -1403,25 +1393,12 @@ mi_set_logging (struct interp *interp,
   mi->event_channel->set_raw (mi->raw_stdout);
 }
 
-/* The MI interpreter's vtable.  */
-
-static const struct interp_procs mi_interp_procs =
-{
-  mi_interpreter_init,		/* init_proc */
-  mi_interpreter_resume,	/* resume_proc */
-  mi_interpreter_suspend,	/* suspend_proc */
-  mi_interpreter_exec,		/* exec_proc */
-  mi_ui_out, 			/* ui_out_proc */
-  mi_set_logging,		/* set_logging_proc */
-  mi_interpreter_pre_command_loop /* pre_command_loop_proc */
-};
-
 /* Factory for MI interpreters.  */
 
 static struct interp *
 mi_interp_factory (const char *name)
 {
-  return interp_new (name, &mi_interp_procs, NULL);
+  return new mi_interp (name);
 }
 
 extern initialize_file_ftype _initialize_mi_interp; /* -Wmissing-prototypes */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index b249f2d..cf4e45a 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -147,8 +147,7 @@ static void print_diff (struct ui_file *file, struct mi_timestamp *start,
 void
 mi_cmd_gdb_exit (char *command, char **argv, int argc)
 {
-  struct mi_interp *mi
-    = (struct mi_interp *) interp_data (current_interpreter ());
+  struct mi_interp *mi = (struct mi_interp *) current_interpreter ();
 
   /* We have to print everything right here because we never return.  */
   if (current_token)
@@ -1974,7 +1973,7 @@ mi_cmd_remove_inferior (char *command, char **argv, int argc)
 static void
 captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
 {
-  struct mi_interp *mi = (struct mi_interp *) interp_data (command_interp ());
+  struct mi_interp *mi = (struct mi_interp *) command_interp ();
   struct cleanup *cleanup;
 
   if (do_timings)
@@ -2066,8 +2065,7 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
 static void
 mi_print_exception (const char *token, struct gdb_exception exception)
 {
-  struct mi_interp *mi
-    = (struct mi_interp *) interp_data (current_interpreter ());
+  struct mi_interp *mi = (struct mi_interp *) current_interpreter ();
 
   fputs_unfiltered (token, mi->raw_stdout);
   fputs_unfiltered ("^error,msg=\"", mi->raw_stdout);
@@ -2190,8 +2188,7 @@ mi_execute_command (const char *cmd, int from_tty)
 	     again.  */
 	  && !command_notifies_uscc_observer (command))
 	{
-	  struct mi_interp *mi
-	    = (struct mi_interp *) top_level_interpreter_data ();
+	  struct mi_interp *mi = (struct mi_interp *) top_level_interpreter ();
 	  int report_change = 0;
 
 	  if (command->thread == -1)
@@ -2378,8 +2375,7 @@ mi_load_progress (const char *section_name,
   int new_section;
   struct ui_out *saved_uiout;
   struct ui_out *uiout;
-  struct mi_interp *mi
-    = (struct mi_interp *) interp_data (current_interpreter ());
+  struct mi_interp *mi = (struct mi_interp *) current_interpreter ();
 
   /* This function is called through deprecated_show_load_progress
      which means uiout may not be correct.  Fix it for the duration
diff --git a/gdb/tui/tui-interp.c b/gdb/tui/tui-interp.c
index e2c0605..702c342 100644
--- a/gdb/tui/tui-interp.c
+++ b/gdb/tui/tui-interp.c
@@ -34,20 +34,32 @@
 #include "observer.h"
 #include "gdbthread.h"
 
-static struct ui_out *tui_ui_out (struct interp *self);
-
 /* Set to 1 when the TUI mode must be activated when we first start
    gdb.  */
 static int tui_start_enabled = 0;
 
+class tui_interp final : public cli_interp_base
+{
+public:
+  explicit tui_interp (const char *name)
+    : cli_interp_base (name)
+  {}
+
+  void init (bool top_level) override;
+  void resume () override;
+  void suspend () override;
+  gdb_exception exec (const char *command_str) override;
+  ui_out *interp_ui_out () override;
+};
+
 /* Returns the INTERP if the INTERP is a TUI, and returns NULL
    otherwise.  */
 
-static struct interp *
+static tui_interp *
 as_tui_interp (struct interp *interp)
 {
   if (strcmp (interp_name (interp), INTERP_TUI) == 0)
-    return interp;
+    return (tui_interp *) interp;
   return NULL;
 }
 
@@ -84,7 +96,7 @@ tui_on_normal_stop (struct bpstats *bs, int print_frame)
 
       thread = inferior_thread ();
       if (should_print_stop_to_console (interp, thread))
-	print_stop_event (tui_ui_out (tui));
+	print_stop_event (tui->interp_ui_out ());
     }
 }
 
@@ -100,7 +112,7 @@ tui_on_signal_received (enum gdb_signal siggnal)
       if (tui == NULL)
 	continue;
 
-      print_signal_received_reason (tui_ui_out (tui), siggnal);
+      print_signal_received_reason (tui->interp_ui_out (), siggnal);
     }
 }
 
@@ -116,7 +128,7 @@ tui_on_end_stepping_range (void)
       if (tui == NULL)
 	continue;
 
-      print_end_stepping_range_reason (tui_ui_out (tui));
+      print_end_stepping_range_reason (tui->interp_ui_out ());
     }
 }
 
@@ -132,7 +144,7 @@ tui_on_signal_exited (enum gdb_signal siggnal)
       if (tui == NULL)
 	continue;
 
-      print_signal_exited_reason (tui_ui_out (tui), siggnal);
+      print_signal_exited_reason (tui->interp_ui_out (), siggnal);
     }
 }
 
@@ -148,7 +160,7 @@ tui_on_exited (int exitstatus)
       if (tui == NULL)
 	continue;
 
-      print_exited_reason (tui_ui_out (tui), exitstatus);
+      print_exited_reason (tui->interp_ui_out (), exitstatus);
     }
 }
 
@@ -164,7 +176,7 @@ tui_on_no_history (void)
       if (tui == NULL)
 	continue;
 
-      print_no_history_reason (tui_ui_out (tui));
+      print_no_history_reason (tui->interp_ui_out ());
     }
 }
 
@@ -215,19 +227,19 @@ tui_on_user_selected_context_changed (user_selected_what selection)
 	continue;
 
       if (selection & USER_SELECTED_INFERIOR)
-	print_selected_inferior (tui_ui_out (tui));
+	print_selected_inferior (tui->interp_ui_out ());
 
       if (tp != NULL
 	  && ((selection & (USER_SELECTED_THREAD | USER_SELECTED_FRAME))))
-	print_selected_thread_frame (tui_ui_out (tui), selection);
+	print_selected_thread_frame (tui->interp_ui_out (), selection);
 
     }
 }
 
 /* These implement the TUI interpreter.  */
 
-static void *
-tui_init (struct interp *self, int top_level)
+void
+tui_interp::init (bool top_level)
 {
   /* Install exit handler to leave the screen in a good shape.  */
   atexit (tui_exit);
@@ -238,12 +250,10 @@ tui_init (struct interp *self, int top_level)
   tui_initialize_win ();
   if (ui_file_isatty (gdb_stdout))
     tui_initialize_readline ();
-
-  return NULL;
 }
 
-static int
-tui_resume (void *data)
+void
+tui_interp::resume ()
 {
   struct ui *ui = current_ui;
   struct ui_file *stream;
@@ -268,19 +278,17 @@ tui_resume (void *data)
 
   if (tui_start_enabled)
     tui_enable ();
-  return 1;
 }
 
-static int
-tui_suspend (void *data)
+void
+tui_interp::suspend ()
 {
   tui_start_enabled = tui_active;
   tui_disable ();
-  return 1;
 }
 
-static struct ui_out *
-tui_ui_out (struct interp *self)
+ui_out *
+tui_interp::interp_ui_out ()
 {
   if (tui_active)
     return tui_out;
@@ -288,31 +296,19 @@ tui_ui_out (struct interp *self)
     return tui_old_uiout;
 }
 
-static struct gdb_exception
-tui_exec (void *data, const char *command_str)
+gdb_exception
+tui_interp::exec (const char *command_str)
 {
   internal_error (__FILE__, __LINE__, _("tui_exec called"));
 }
 
-/* The TUI interpreter's vtable.  */
-
-static const struct interp_procs tui_interp_procs = {
-  tui_init,
-  tui_resume,
-  tui_suspend,
-  tui_exec,
-  tui_ui_out,
-  cli_set_logging,
-  cli_interpreter_pre_command_loop,
-  cli_interpreter_supports_command_editing,
-};
 
 /* Factory for TUI interpreters.  */
 
 static struct interp *
 tui_interp_factory (const char *name)
 {
-  return interp_new (name, &tui_interp_procs, NULL);
+  return new tui_interp (name);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */