expression.h

/* Definitions for expressions stored in reversed prefix form, for GDB.

   Copyright (C) 1986-2015 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/>.  */

#if !defined (EXPRESSION_H)
#define EXPRESSION_H 1


#include "symtab.h"		/* Needed for "struct block" type.  */
#include "doublest.h"		/* Needed for DOUBLEST.  */


/* Definitions for saved C expressions.  */

/* An expression is represented as a vector of union exp_element's.
   Each exp_element is an opcode, except that some opcodes cause
   the following exp_element to be treated as a long or double constant
   or as a variable.  The opcodes are obeyed, using a stack for temporaries.
   The value is left on the temporary stack at the end.  */

/* When it is necessary to include a string,
   it can occupy as many exp_elements as it needs.
   We find the length of the string using strlen,
   divide to find out how many exp_elements are used up,
   and skip that many.  Strings, like numbers, are indicated
   by the preceding opcode.  */

enum exp_opcode
  {
#define OP(name) name ,

#include "std-operator.def"

    /* First extension operator.  Individual language modules define extra
       operators in *.def include files below with numbers higher than
       OP_EXTENDED0.  */
    OP (OP_EXTENDED0)

/* Language specific operators.  */
#include "ada-operator.def"

#undef OP

    /* Existing only to swallow the last comma (',') from last .inc file.  */
    OP_UNUSED_LAST
  };

union exp_element
  {
    enum exp_opcode opcode;
    struct symbol *symbol;
    LONGEST longconst;
    DOUBLEST doubleconst;
    gdb_byte decfloatconst[16];
    /* Really sizeof (union exp_element) characters (or less for the last
       element of a string).  */
    char string;
    struct type *type;
    struct internalvar *internalvar;
    const struct block *block;
    struct objfile *objfile;
  };

struct expression
  {
    const struct language_defn *language_defn;	/* language it was
						   entered in.  */
    struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
    int nelts;
    union exp_element elts[1];
  };

/* Macros for converting between number of expression elements and bytes
   to store that many expression elements.  */

#define EXP_ELEM_TO_BYTES(elements) \
    ((elements) * sizeof (union exp_element))
#define BYTES_TO_EXP_ELEM(bytes) \
    (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))

/* From parse.c */

extern struct expression *parse_expression (const char *);

extern struct expression *parse_expression_with_language (const char *string,
							  enum language lang);

extern struct type *parse_expression_for_completion (const char *, char **,
						     enum type_code *);

extern struct expression *parse_exp_1 (const char **, CORE_ADDR pc,
				       const struct block *, int);

/* For use by parsers; set if we want to parse an expression and
   attempt completion.  */
extern int parse_completion;

/* The innermost context required by the stack and register variables
   we've encountered so far.  To use this, set it to NULL, then call
   parse_<whatever>, then look at it.  */
extern const struct block *innermost_block;

/* From eval.c */

/* Values of NOSIDE argument to eval_subexp.  */

enum noside
  {
    EVAL_NORMAL,
    EVAL_SKIP,			/* Only effect is to increment pos.  */
    EVAL_AVOID_SIDE_EFFECTS	/* Don't modify any variables or
				   call any functions.  The value
				   returned will have the correct
				   type, and will have an
				   approximately correct lvalue
				   type (inaccuracy: anything that is
				   listed as being in a register in
				   the function in which it was
				   declared will be lval_register).
				   Ideally this would not even read
				   target memory, but currently it
				   does in many situations.  */
  };

extern struct value *evaluate_subexp_standard
  (struct type *, struct expression *, int *, enum noside);

/* From expprint.c */

extern void print_expression (struct expression *, struct ui_file *);

extern char *op_name (struct expression *exp, enum exp_opcode opcode);

extern char *op_string (enum exp_opcode);

extern void dump_raw_expression (struct expression *,
				 struct ui_file *, char *);
extern void dump_prefix_expression (struct expression *, struct ui_file *);

#endif /* !defined (EXPRESSION_H) */