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     LONGEST longconst;
  68     DOUBLEST doubleconst;
  69     gdb_byte decfloatconst[16];
  70     /* Really sizeof (union exp_element) characters (or less for the last
  71        element of a string).  */
  72     char string;
  73     struct type *type;
  74     struct internalvar *internalvar;
  75     const struct block *block;
  76     struct objfile *objfile;
  77   };
  78
  79 struct expression
  80   {
  81     const struct language_defn *language_defn;  /* language it was
  82                                                    entered in.  */
  83     struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
  84     int nelts;
  85     union exp_element elts[1];
  86   };
  87
  88 typedef gdb::unique_xmalloc_ptr<expression> expression_up;
  89
  90 /* Macros for converting between number of expression elements and bytes
  91    to store that many expression elements.  */
  92
  93 #define EXP_ELEM_TO_BYTES(elements) \
  94     ((elements) * sizeof (union exp_element))
  95 #define BYTES_TO_EXP_ELEM(bytes) \
  96     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
  97
  98 /* From parse.c */
  99
 100 extern expression_up parse_expression (const char *);
 101
 102 extern expression_up parse_expression_with_language (const char *string,
 103                                                      enum language lang);
 104
 105 extern struct type *parse_expression_for_completion (const char *, char **,
 106                                                      enum type_code *);
 107
 108 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 109                                   const struct block *, int);
 110
 111 /* For use by parsers; set if we want to parse an expression and
 112    attempt completion.  */
 113 extern int parse_completion;
 114
 115 /* The innermost context required by the stack and register variables
 116    we've encountered so far.  To use this, set it to NULL, then call
 117    parse_<whatever>, then look at it.  */
 118 extern const struct block *innermost_block;
 119
 120 /* From eval.c */
 121
 122 /* Values of NOSIDE argument to eval_subexp.  */
 123
 124 enum noside
 125   {
 126     EVAL_NORMAL,
 127     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 128     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 129                                    call any functions.  The value
 130                                    returned will have the correct
 131                                    type, and will have an
 132                                    approximately correct lvalue
 133                                    type (inaccuracy: anything that is
 134                                    listed as being in a register in
 135                                    the function in which it was
 136                                    declared will be lval_register).
 137                                    Ideally this would not even read
 138                                    target memory, but currently it
 139                                    does in many situations.  */
 140   };
 141
 142 extern struct value *evaluate_subexp_standard
 143   (struct type *, struct expression *, int *, enum noside);
 144
 145 /* From expprint.c */
 146
 147 extern void print_expression (struct expression *, struct ui_file *);
 148
 149 extern const char *op_name (struct expression *exp, enum exp_opcode opcode);
 150
 151 extern const char *op_string (enum exp_opcode);
 152
 153 extern void dump_raw_expression (struct expression *,
 154                                  struct ui_file *, const char *);
 155 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 156
 157 /* In an OP_RANGE expression, either bound could be empty, indicating
 158    that its value is by default that of the corresponding bound of the
 159    array or string.  So we have four sorts of subrange.  This
 160    enumeration type is to identify this.  */
 161
 162 enum range_type
 163   {
 164     BOTH_BOUND_DEFAULT,         /* "(:)"  */
 165     LOW_BOUND_DEFAULT,          /* "(:high)"  */
 166     HIGH_BOUND_DEFAULT,         /* "(low:)"  */
 167     NONE_BOUND_DEFAULT          /* "(low:high)"  */
 168   };
 169
 170 #endif /* !defined (EXPRESSION_H) */