binutils-gdb/gdb/extension.h

/* Interface between gdb and its extension languages.

   Copyright (C) 2014-2018 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 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.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifndef EXTENSION_H
#define EXTENSION_H

#include "mi/mi-cmds.h" /* For PRINT_NO_VALUES, etc.  */
#include "common/vec.h"

struct breakpoint;
struct command_line;
struct frame_info;
struct language_defn;
struct objfile;
struct extension_language_defn;
struct type;
struct ui_file;
struct ui_out;
struct value;
struct value_print_options;

/* A function to load and process a script file.
   The file has been opened and is ready to be read from the beginning.
   Any exceptions are not caught, and are passed to the caller.  */
typedef void script_sourcer_func (const struct extension_language_defn *,
				  FILE *stream, const char *filename);

/* A function to load and process a script for an objfile.
   The file has been opened and is ready to be read from the beginning.
   Any exceptions are not caught, and are passed to the caller.  */
typedef void objfile_script_sourcer_func
  (const struct extension_language_defn *,
   struct objfile *, FILE *stream, const char *filename);

/* A function to execute a script for an objfile.
   Any exceptions are not caught, and are passed to the caller.  */
typedef void objfile_script_executor_func
  (const struct extension_language_defn *,
   struct objfile *, const char *name, const char *script);

/* Enum of each extension(/scripting) language.  */

enum extension_language
  {
    EXT_LANG_NONE,
    EXT_LANG_GDB,
    EXT_LANG_PYTHON,
    EXT_LANG_GUILE
  };

/* Extension language frame-filter status return values.  */

enum ext_lang_bt_status
  {
    /* Return when an error has occurred in processing frame filters,
       or when printing the stack.  */
    EXT_LANG_BT_ERROR = -1,

    /* Return from internal routines to indicate that the function
       succeeded.  */
    EXT_LANG_BT_OK = 1,

    /* Return when the frame filter process is complete, but there
       were no filter registered and enabled to process.  */
    EXT_LANG_BT_NO_FILTERS = 2
  };

/* Flags to pass to apply_extlang_frame_filter.  */

enum frame_filter_flag
  {
    /* Set this flag if frame level is to be printed.  */
    PRINT_LEVEL = 1 << 0,

    /* Set this flag if frame information is to be printed.  */
    PRINT_FRAME_INFO = 1 << 1,

    /* Set this flag if frame arguments are to be printed.  */
    PRINT_ARGS = 1 << 2,

    /* Set this flag if frame locals are to be printed.  */
    PRINT_LOCALS = 1 << 3,

    /* Set this flag if a "More frames" message is to be printed.  */
    PRINT_MORE_FRAMES = 1 << 4,

    /* Set this flag if elided frames should not be printed.  */
    PRINT_HIDE = 1 << 5,
  };

DEF_ENUM_FLAGS_TYPE (enum frame_filter_flag, frame_filter_flags);

/* A choice of the different frame argument printing strategies that
   can occur in different cases of frame filter instantiation.  */

enum ext_lang_frame_args
  {
    /* Print no values for arguments when invoked from the MI. */
    NO_VALUES = PRINT_NO_VALUES,

    MI_PRINT_ALL_VALUES = PRINT_ALL_VALUES,

    /* Print only simple values (what MI defines as "simple") for
       arguments when invoked from the MI. */
    MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,

    /* Print only scalar values for arguments when invoked from the CLI. */
    CLI_SCALAR_VALUES,

    /* Print all values for arguments when invoked from the CLI. */
    CLI_ALL_VALUES
  };

/* The possible results of
   extension_language_ops.breakpoint_cond_says_stop.  */

enum ext_lang_bp_stop
  {
    /* No "stop" condition is set.  */
    EXT_LANG_BP_STOP_UNSET,

    /* A "stop" condition is set, and it says "don't stop".  */
    EXT_LANG_BP_STOP_NO,

    /* A "stop" condition is set, and it says "stop".  */
    EXT_LANG_BP_STOP_YES
  };

/* Table of type printers associated with the global typedef table.  */

struct ext_lang_type_printers
{
  ext_lang_type_printers ();
  ~ext_lang_type_printers ();

  DISABLE_COPY_AND_ASSIGN (ext_lang_type_printers);

  /* Type-printers from Python.  */
  void *py_type_printers = nullptr;
};

/* The return code for some API calls.  */

enum ext_lang_rc
{
  /* The operation completed successfully.  */
  EXT_LANG_RC_OK,

  /* The operation was not performed (e.g., no pretty-printer).  */
  EXT_LANG_RC_NOP,

  /* There was an error (e.g., Python error while printing a value).
     When an error occurs no further extension languages are tried.
     This is to preserve existing behaviour, and because it's convenient
     for Python developers.
     Note: This is different than encountering a memory error trying to read
     a value for pretty-printing.  Here we're referring to, e.g., programming
     errors that trigger an exception in the extension language.  */
  EXT_LANG_RC_ERROR
};

/* A type which holds its extension language specific xmethod worker data.  */

struct xmethod_worker
{
  xmethod_worker (const extension_language_defn *extlang)
  : m_extlang (extlang)
  {}

  virtual ~xmethod_worker () = default;

  /* Invoke the xmethod encapsulated in this worker and return the result.
     The method is invoked on OBJ with arguments in the ARGS array.  NARGS is
     the length of the this array.  */

  virtual value *invoke (value *obj, value **args, int nargs) = 0;

  /* Return the arg types of the xmethod encapsulated in this worker.
     An array of arg types is returned.  The length of the array is returned in
     NARGS.  The type of the 'this' object is returned as the first element of
     array.  */

  type **get_arg_types (int *nargs);

  /* Return the type of the result of the xmethod encapsulated in this worker.
     OBJECT, ARGS, NARGS are the same as for invoke.  */

  type *get_result_type (value *object, value **args, int nargs);

private:

  /* Return the types of the arguments the method takes.  The number of
     arguments is returned in NARGS, and their types are returned in the array
     ARGTYPES.  */

  virtual enum ext_lang_rc do_get_arg_types
    (int *nargs, struct type ***arg_types) = 0;

  /* Fetch the type of the result of the method implemented by this worker.
     OBJECT, ARGS, NARGS are the same as for the invoked method.  The result
     type is stored in *RESULT_TYPE.  */

  virtual enum ext_lang_rc do_get_result_type
    (struct value *obj, struct value **args, int nargs,
     struct type **result_type_ptr) = 0;

  /* The language the xmethod worker is implemented in.  */

  const extension_language_defn *m_extlang;
};

typedef std::unique_ptr<xmethod_worker> xmethod_worker_up;

/* The interface for gdb's own extension(/scripting) language.  */
extern const struct extension_language_defn extension_language_gdb;

extern const struct extension_language_defn *get_ext_lang_defn
  (enum extension_language lang);

extern const struct extension_language_defn *get_ext_lang_of_file
  (const char *file);

extern int ext_lang_present_p (const struct extension_language_defn *);

extern int ext_lang_initialized_p (const struct extension_language_defn *);

extern void throw_ext_lang_unsupported
  (const struct extension_language_defn *);

/* Accessors for "public" attributes of the extension language definition.  */

extern enum extension_language ext_lang_kind
  (const struct extension_language_defn *);

extern const char *ext_lang_name (const struct extension_language_defn *);

extern const char *ext_lang_capitalized_name
  (const struct extension_language_defn *);

extern const char *ext_lang_suffix (const struct extension_language_defn *);

extern const char *ext_lang_auto_load_suffix
  (const struct extension_language_defn *);

extern script_sourcer_func *ext_lang_script_sourcer
  (const struct extension_language_defn *);

extern objfile_script_sourcer_func *ext_lang_objfile_script_sourcer
  (const struct extension_language_defn *);

extern objfile_script_executor_func *ext_lang_objfile_script_executor
  (const struct extension_language_defn *);

extern int ext_lang_auto_load_enabled (const struct extension_language_defn *);

/* Wrappers for each extension language API function that iterate over all
   extension languages.  */

extern void finish_ext_lang_initialization (void);

extern void eval_ext_lang_from_control_command (struct command_line *cmd);

extern void auto_load_ext_lang_scripts_for_objfile (struct objfile *);

extern char *apply_ext_lang_type_printers (struct ext_lang_type_printers *,
					   struct type *);

extern int apply_ext_lang_val_pretty_printer
  (struct type *type,
   LONGEST embedded_offset, CORE_ADDR address,
   struct ui_file *stream, int recurse,
   struct value *val, const struct value_print_options *options,
   const struct language_defn *language);

extern enum ext_lang_bt_status apply_ext_lang_frame_filter
  (struct frame_info *frame, frame_filter_flags flags,
   enum ext_lang_frame_args args_type,
   struct ui_out *out, int frame_low, int frame_high);

extern void preserve_ext_lang_values (struct objfile *, htab_t copied_types);

extern const struct extension_language_defn *get_breakpoint_cond_ext_lang
  (struct breakpoint *b, enum extension_language skip_lang);

extern int breakpoint_ext_lang_cond_says_stop (struct breakpoint *);

/* If a method with name METHOD_NAME is to be invoked on an object of type
   TYPE, then all extension languages are searched for implementations of
   methods with name METHOD_NAME.  All matches found are appended to the WORKERS
   vector.  */

extern void get_matching_xmethod_workers
  (struct type *type, const char *method_name,
   std::vector<xmethod_worker_up> *workers);

#endif /* EXTENSION_H */