binutils-gdb/gdb/m2-lang.c

/* Modula 2 language support routines for GDB, the GNU debugger.

   Copyright (C) 1992-2020 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/>.  */

#include "defs.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "expression.h"
#include "parser-defs.h"
#include "language.h"
#include "varobj.h"
#include "m2-lang.h"
#include "c-lang.h"
#include "valprint.h"
#include "gdbarch.h"

static void m2_printchar (int, struct type *, struct ui_file *);

/* FIXME:  This is a copy of the same function from c-exp.y.  It should
   be replaced with a true Modula version.  */

static void
m2_printchar (int c, struct type *type, struct ui_file *stream)
{
  fputs_filtered ("'", stream);
  LA_EMIT_CHAR (c, type, stream, '\'');
  fputs_filtered ("'", stream);
}

static struct value *
evaluate_subexp_modula2 (struct type *expect_type, struct expression *exp,
			 int *pos, enum noside noside)
{
  enum exp_opcode op = exp->elts[*pos].opcode;
  struct value *arg1;
  struct value *arg2;
  struct type *type;

  switch (op)
    {
    case UNOP_HIGH:
      (*pos)++;
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);

      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
	return arg1;
      else
	{
	  arg1 = coerce_ref (arg1);
	  type = check_typedef (value_type (arg1));

	  if (m2_is_unbounded_array (type))
	    {
	      struct value *temp = arg1;

	      type = type->field (1).type ();
	      /* i18n: Do not translate the "_m2_high" part!  */
	      arg1 = value_struct_elt (&temp, NULL, "_m2_high", NULL,
				       _("unbounded structure "
					 "missing _m2_high field"));
	  
	      if (value_type (arg1) != type)
		arg1 = value_cast (type, arg1);
	    }
	}
      return arg1;

    case BINOP_SUBSCRIPT:
      (*pos)++;
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      /* If the user attempts to subscript something that is not an
         array or pointer type (like a plain int variable for example),
         then report this as an error.  */

      arg1 = coerce_ref (arg1);
      type = check_typedef (value_type (arg1));

      if (m2_is_unbounded_array (type))
	{
	  struct value *temp = arg1;
	  type = type->field (0).type ();
	  if (type == NULL || (type->code () != TYPE_CODE_PTR))
	    {
	      warning (_("internal error: unbounded "
			 "array structure is unknown"));
	      return evaluate_subexp_standard (expect_type, exp, pos, noside);
	    }
	  /* i18n: Do not translate the "_m2_contents" part!  */
	  arg1 = value_struct_elt (&temp, NULL, "_m2_contents", NULL,
				   _("unbounded structure "
				     "missing _m2_contents field"));
	  
	  if (value_type (arg1) != type)
	    arg1 = value_cast (type, arg1);

	  check_typedef (value_type (arg1));
	  return value_ind (value_ptradd (arg1, value_as_long (arg2)));
	}
      else
	if (type->code () != TYPE_CODE_ARRAY)
	  {
	    if (type->name ())
	      error (_("cannot subscript something of type `%s'"),
		     type->name ());
	    else
	      error (_("cannot subscript requested type"));
	  }

      if (noside == EVAL_AVOID_SIDE_EFFECTS)
	return value_zero (TYPE_TARGET_TYPE (type), VALUE_LVAL (arg1));
      else
	return value_subscript (arg1, value_as_long (arg2));

    default:
      return evaluate_subexp_standard (expect_type, exp, pos, noside);
    }

 nosideret:
  return value_from_longest (builtin_type (exp->gdbarch)->builtin_int, 1);
}


/* Table of operators and their precedences for printing expressions.  */

static const struct op_print m2_op_print_tab[] =
{
  {"+", BINOP_ADD, PREC_ADD, 0},
  {"+", UNOP_PLUS, PREC_PREFIX, 0},
  {"-", BINOP_SUB, PREC_ADD, 0},
  {"-", UNOP_NEG, PREC_PREFIX, 0},
  {"*", BINOP_MUL, PREC_MUL, 0},
  {"/", BINOP_DIV, PREC_MUL, 0},
  {"DIV", BINOP_INTDIV, PREC_MUL, 0},
  {"MOD", BINOP_REM, PREC_MUL, 0},
  {":=", BINOP_ASSIGN, PREC_ASSIGN, 1},
  {"OR", BINOP_LOGICAL_OR, PREC_LOGICAL_OR, 0},
  {"AND", BINOP_LOGICAL_AND, PREC_LOGICAL_AND, 0},
  {"NOT", UNOP_LOGICAL_NOT, PREC_PREFIX, 0},
  {"=", BINOP_EQUAL, PREC_EQUAL, 0},
  {"<>", BINOP_NOTEQUAL, PREC_EQUAL, 0},
  {"<=", BINOP_LEQ, PREC_ORDER, 0},
  {">=", BINOP_GEQ, PREC_ORDER, 0},
  {">", BINOP_GTR, PREC_ORDER, 0},
  {"<", BINOP_LESS, PREC_ORDER, 0},
  {"^", UNOP_IND, PREC_PREFIX, 0},
  {"@", BINOP_REPEAT, PREC_REPEAT, 0},
  {"CAP", UNOP_CAP, PREC_BUILTIN_FUNCTION, 0},
  {"CHR", UNOP_CHR, PREC_BUILTIN_FUNCTION, 0},
  {"ORD", UNOP_ORD, PREC_BUILTIN_FUNCTION, 0},
  {"FLOAT", UNOP_FLOAT, PREC_BUILTIN_FUNCTION, 0},
  {"HIGH", UNOP_HIGH, PREC_BUILTIN_FUNCTION, 0},
  {"MAX", UNOP_MAX, PREC_BUILTIN_FUNCTION, 0},
  {"MIN", UNOP_MIN, PREC_BUILTIN_FUNCTION, 0},
  {"ODD", UNOP_ODD, PREC_BUILTIN_FUNCTION, 0},
  {"TRUNC", UNOP_TRUNC, PREC_BUILTIN_FUNCTION, 0},
  {NULL, OP_NULL, PREC_BUILTIN_FUNCTION, 0}
};

/* The built-in types of Modula-2.  */

enum m2_primitive_types {
  m2_primitive_type_char,
  m2_primitive_type_int,
  m2_primitive_type_card,
  m2_primitive_type_real,
  m2_primitive_type_bool,
  nr_m2_primitive_types
};

const struct exp_descriptor exp_descriptor_modula2 = 
{
  print_subexp_standard,
  operator_length_standard,
  operator_check_standard,
  op_name_standard,
  dump_subexp_body_standard,
  evaluate_subexp_modula2
};

/* Class representing the M2 language.  */

class m2_language : public language_defn
{
public:
  m2_language ()
    : language_defn (language_m2)
  { /* Nothing.  */ }

  /* See language.h.  */

  const char *name () const override
  { return "modula-2"; }

  /* See language.h.  */

  const char *natural_name () const override
  { return "Modula-2"; }

  /* See language.h.  */
  void language_arch_info (struct gdbarch *gdbarch,
			   struct language_arch_info *lai) const override
  {
    const struct builtin_m2_type *builtin = builtin_m2_type (gdbarch);

    lai->string_char_type = builtin->builtin_char;
    lai->primitive_type_vector
      = GDBARCH_OBSTACK_CALLOC (gdbarch, nr_m2_primitive_types + 1,
				struct type *);

    lai->primitive_type_vector [m2_primitive_type_char]
      = builtin->builtin_char;
    lai->primitive_type_vector [m2_primitive_type_int]
      = builtin->builtin_int;
    lai->primitive_type_vector [m2_primitive_type_card]
      = builtin->builtin_card;
    lai->primitive_type_vector [m2_primitive_type_real]
      = builtin->builtin_real;
    lai->primitive_type_vector [m2_primitive_type_bool]
      = builtin->builtin_bool;

    lai->bool_type_symbol = "BOOLEAN";
    lai->bool_type_default = builtin->builtin_bool;
  }

  /* See language.h.  */

  void print_type (struct type *type, const char *varstring,
		   struct ui_file *stream, int show, int level,
		   const struct type_print_options *flags) const override
  {
    m2_print_type (type, varstring, stream, show, level, flags);
  }

  /* See language.h.  */

  void value_print_inner
	(struct value *val, struct ui_file *stream, int recurse,
	 const struct value_print_options *options) const override
  {
    return m2_value_print_inner (val, stream, recurse, options);
  }

  /* See language.h.  */

  int parser (struct parser_state *ps) const override
  {
    return m2_parse (ps);
  }

  /* See language.h.  */

  void emitchar (int ch, struct type *chtype,
		 struct ui_file *stream, int quoter) const override
  {
    ch &= 0xFF;			/* Avoid sign bit follies.  */

    if (PRINT_LITERAL_FORM (ch))
      {
	if (ch == '\\' || ch == quoter)
	  fputs_filtered ("\\", stream);
	fprintf_filtered (stream, "%c", ch);
      }
    else
      {
	switch (ch)
	  {
	  case '\n':
	    fputs_filtered ("\\n", stream);
	    break;
	  case '\b':
	    fputs_filtered ("\\b", stream);
	    break;
	  case '\t':
	    fputs_filtered ("\\t", stream);
	    break;
	  case '\f':
	    fputs_filtered ("\\f", stream);
	    break;
	  case '\r':
	    fputs_filtered ("\\r", stream);
	    break;
	  case '\033':
	    fputs_filtered ("\\e", stream);
	    break;
	  case '\007':
	    fputs_filtered ("\\a", stream);
	    break;
	  default:
	    fprintf_filtered (stream, "\\%.3o", (unsigned int) ch);
	    break;
	  }
      }
  }

  /* See language.h.  */

  void printchar (int ch, struct type *chtype,
		  struct ui_file *stream) const override
  {
    m2_printchar (ch, chtype, stream);
  }

  /* See language.h.  */

  void printstr (struct ui_file *stream, struct type *elttype,
		 const gdb_byte *string, unsigned int length,
		 const char *encoding, int force_ellipses,
		 const struct value_print_options *options) const override
  {
    unsigned int i;
    unsigned int things_printed = 0;
    int in_quotes = 0;
    int need_comma = 0;

    if (length == 0)
      {
	fputs_filtered ("\"\"", gdb_stdout);
	return;
      }

    for (i = 0; i < length && things_printed < options->print_max; ++i)
      {
	/* Position of the character we are examining
	   to see whether it is repeated.  */
	unsigned int rep1;
	/* Number of repetitions we have detected so far.  */
	unsigned int reps;

	QUIT;

	if (need_comma)
	  {
	    fputs_filtered (", ", stream);
	    need_comma = 0;
	  }

	rep1 = i + 1;
	reps = 1;
	while (rep1 < length && string[rep1] == string[i])
	  {
	    ++rep1;
	    ++reps;
	  }

	if (reps > options->repeat_count_threshold)
	  {
	    if (in_quotes)
	      {
		fputs_filtered ("\", ", stream);
		in_quotes = 0;
	      }
	    m2_printchar (string[i], elttype, stream);
	    fprintf_filtered (stream, " <repeats %u times>", reps);
	    i = rep1 - 1;
	    things_printed += options->repeat_count_threshold;
	    need_comma = 1;
	  }
	else
	  {
	    if (!in_quotes)
	      {
		fputs_filtered ("\"", stream);
		in_quotes = 1;
	      }
	    LA_EMIT_CHAR (string[i], elttype, stream, '"');
	    ++things_printed;
	  }
      }

    /* Terminate the quotes if necessary.  */
    if (in_quotes)
      fputs_filtered ("\"", stream);

    if (force_ellipses || i < length)
      fputs_filtered ("...", stream);
  }

  /* See language.h.  */

  void print_typedef (struct type *type, struct symbol *new_symbol,
		      struct ui_file *stream) const override
  {
    m2_print_typedef (type, new_symbol, stream);
  }

  /* See language.h.  */

  bool is_string_type_p (struct type *type) const override
  {
    type = check_typedef (type);
    if (type->code () == TYPE_CODE_ARRAY
	&& TYPE_LENGTH (type) > 0
	&& TYPE_LENGTH (TYPE_TARGET_TYPE (type)) > 0)
      {
	struct type *elttype = check_typedef (TYPE_TARGET_TYPE (type));

	if (TYPE_LENGTH (elttype) == 1
	    && (elttype->code () == TYPE_CODE_INT
		|| elttype->code () == TYPE_CODE_CHAR))
	  return true;
      }

    return false;
  }

  /* See language.h.  */

  bool c_style_arrays_p () const override
  { return false; }

  /* See language.h.  Despite not having C-style arrays, Modula-2 uses 0
     for its string lower bounds.  */

  char string_lower_bound () const override
  { return 0; }

  /* See language.h.  */

  bool range_checking_on_by_default () const override
  { return true; }

  /* See language.h.  */

  const struct exp_descriptor *expression_ops () const override
  { return &exp_descriptor_modula2; }

  /* See language.h.  */

  const struct op_print *opcode_print_table () const override
  { return m2_op_print_tab; }
};

/* Single instance of the M2 language.  */

static m2_language m2_language_defn;

static void *
build_m2_types (struct gdbarch *gdbarch)
{
  struct builtin_m2_type *builtin_m2_type
    = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct builtin_m2_type);

  /* Modula-2 "pervasive" types.  NOTE:  these can be redefined!!! */
  builtin_m2_type->builtin_int
    = arch_integer_type (gdbarch, gdbarch_int_bit (gdbarch), 0, "INTEGER");
  builtin_m2_type->builtin_card
    = arch_integer_type (gdbarch, gdbarch_int_bit (gdbarch), 1, "CARDINAL");
  builtin_m2_type->builtin_real
    = arch_float_type (gdbarch, gdbarch_float_bit (gdbarch), "REAL",
		       gdbarch_float_format (gdbarch));
  builtin_m2_type->builtin_char
    = arch_character_type (gdbarch, TARGET_CHAR_BIT, 1, "CHAR");
  builtin_m2_type->builtin_bool
    = arch_boolean_type (gdbarch, gdbarch_int_bit (gdbarch), 1, "BOOLEAN");

  return builtin_m2_type;
}

static struct gdbarch_data *m2_type_data;

const struct builtin_m2_type *
builtin_m2_type (struct gdbarch *gdbarch)
{
  return (const struct builtin_m2_type *) gdbarch_data (gdbarch, m2_type_data);
}


/* Initialization for Modula-2 */

void _initialize_m2_language ();
void
_initialize_m2_language ()
{
  m2_type_data = gdbarch_data_register_post_init (build_m2_types);
}