gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2
   3    Copyright (C) 1986-2017 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #if !defined (EXPRESSION_H)
  21 #define EXPRESSION_H 1
  22
  23
  24 #include "symtab.h"             /* Needed for "struct block" type.  */
  25 #include "doublest.h"           /* Needed for DOUBLEST.  */
  26
  27
  28 /* Definitions for saved C expressions.  */
  29
  30 /* An expression is represented as a vector of union exp_element's.
  31    Each exp_element is an opcode, except that some opcodes cause
  32    the following exp_element to be treated as a long or double constant
  33    or as a variable.  The opcodes are obeyed, using a stack for temporaries.
  34    The value is left on the temporary stack at the end.  */
  35
  36 /* When it is necessary to include a string,
  37    it can occupy as many exp_elements as it needs.
  38    We find the length of the string using strlen,
  39    divide to find out how many exp_elements are used up,
  40    and skip that many.  Strings, like numbers, are indicated
  41    by the preceding opcode.  */
  42
  43 enum exp_opcode
  44   {
  45 #define OP(name) name ,
  46
  47 #include "std-operator.def"
  48
  49     /* First extension operator.  Individual language modules define extra
  50        operators in *.def include files below with numbers higher than
  51        OP_EXTENDED0.  */
  52     OP (OP_EXTENDED0)
  53
  54 /* Language specific operators.  */
  55 #include "ada-operator.def"
  56
  57 #undef OP
  58
  59     /* Existing only to swallow the last comma (',') from last .inc file.  */
  60     OP_UNUSED_LAST
  61   };
  62
  63 union exp_element
  64   {
  65     enum exp_opcode opcode;
  66     struct symbol *symbol;
  67     struct minimal_symbol *msymbol;
  68     LONGEST longconst;
  69     DOUBLEST doubleconst;
  70     gdb_byte decfloatconst[16];
  71     /* Really sizeof (union exp_element) characters (or less for the last
  72        element of a string).  */
  73     char string;
  74     struct type *type;
  75     struct internalvar *internalvar;
  76     const struct block *block;
  77     struct objfile *objfile;
  78   };
  79
  80 struct expression
  81   {
  82     const struct language_defn *language_defn;  /* language it was
  83                                                    entered in.  */
  84     struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
  85     int nelts;
  86     union exp_element elts[1];
  87   };
  88
  89 typedef gdb::unique_xmalloc_ptr<expression> expression_up;
  90
  91 /* Macros for converting between number of expression elements and bytes
  92    to store that many expression elements.  */
  93
  94 #define EXP_ELEM_TO_BYTES(elements) \
  95     ((elements) * sizeof (union exp_element))
  96 #define BYTES_TO_EXP_ELEM(bytes) \
  97     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
  98
  99 /* From parse.c */
 100
 101 extern expression_up parse_expression (const char *);
 102
 103 extern expression_up parse_expression_with_language (const char *string,
 104                                                      enum language lang);
 105
 106 extern struct type *parse_expression_for_completion (const char *, char **,
 107                                                      enum type_code *);
 108
 109 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 110                                   const struct block *, int);
 111
 112 /* For use by parsers; set if we want to parse an expression and
 113    attempt completion.  */
 114 extern int parse_completion;
 115
 116 /* The innermost context required by the stack and register variables
 117    we've encountered so far.  To use this, set it to NULL, then call
 118    parse_<whatever>, then look at it.  */
 119 extern const struct block *innermost_block;
 120
 121 /* From eval.c */
 122
 123 /* Values of NOSIDE argument to eval_subexp.  */
 124
 125 enum noside
 126   {
 127     EVAL_NORMAL,
 128     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 129     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 130                                    call any functions.  The value
 131                                    returned will have the correct
 132                                    type, and will have an
 133                                    approximately correct lvalue
 134                                    type (inaccuracy: anything that is
 135                                    listed as being in a register in
 136                                    the function in which it was
 137                                    declared will be lval_register).
 138                                    Ideally this would not even read
 139                                    target memory, but currently it
 140                                    does in many situations.  */
 141   };
 142
 143 extern struct value *evaluate_subexp_standard
 144   (struct type *, struct expression *, int *, enum noside);
 145
 146 /* From expprint.c */
 147
 148 extern void print_expression (struct expression *, struct ui_file *);
 149
 150 extern const char *op_name (struct expression *exp, enum exp_opcode opcode);
 151
 152 extern const char *op_string (enum exp_opcode);
 153
 154 extern void dump_raw_expression (struct expression *,
 155                                  struct ui_file *, const char *);
 156 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 157
 158 /* In an OP_RANGE expression, either bound could be empty, indicating
 159    that its value is by default that of the corresponding bound of the
 160    array or string.  So we have four sorts of subrange.  This
 161    enumeration type is to identify this.  */
 162
 163 enum range_type
 164   {
 165     BOTH_BOUND_DEFAULT,         /* "(:)"  */
 166     LOW_BOUND_DEFAULT,          /* "(:high)"  */
 167     HIGH_BOUND_DEFAULT,         /* "(low:)"  */
 168     NONE_BOUND_DEFAULT          /* "(low:high)"  */
 169   };
 170
 171 #endif /* !defined (EXPRESSION_H) */