gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2
   3    Copyright (C) 1986-2018 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
  26
  27 /* Definitions for saved C expressions.  */
  28
  29 /* An expression is represented as a vector of union exp_element's.
  30    Each exp_element is an opcode, except that some opcodes cause
  31    the following exp_element to be treated as a long or double constant
  32    or as a variable.  The opcodes are obeyed, using a stack for temporaries.
  33    The value is left on the temporary stack at the end.  */
  34
  35 /* When it is necessary to include a string,
  36    it can occupy as many exp_elements as it needs.
  37    We find the length of the string using strlen,
  38    divide to find out how many exp_elements are used up,
  39    and skip that many.  Strings, like numbers, are indicated
  40    by the preceding opcode.  */
  41
  42 enum exp_opcode
  43   {
  44 #define OP(name) name ,
  45
  46 #include "std-operator.def"
  47
  48     /* First extension operator.  Individual language modules define extra
  49        operators in *.def include files below with numbers higher than
  50        OP_EXTENDED0.  */
  51     OP (OP_EXTENDED0)
  52
  53 /* Language specific operators.  */
  54 #include "ada-operator.def"
  55
  56 #undef OP
  57
  58     /* Existing only to swallow the last comma (',') from last .inc file.  */
  59     OP_UNUSED_LAST
  60   };
  61
  62 union exp_element
  63   {
  64     enum exp_opcode opcode;
  65     struct symbol *symbol;
  66     struct minimal_symbol *msymbol;
  67     LONGEST longconst;
  68     gdb_byte floatconst[16];
  69     /* Really sizeof (union exp_element) characters (or less for the last
  70        element of a string).  */
  71     char string;
  72     struct type *type;
  73     struct internalvar *internalvar;
  74     const struct block *block;
  75     struct objfile *objfile;
  76   };
  77
  78 struct expression
  79   {
  80     const struct language_defn *language_defn;  /* language it was
  81                                                    entered in.  */
  82     struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
  83     int nelts;
  84     union exp_element elts[1];
  85   };
  86
  87 typedef gdb::unique_xmalloc_ptr<expression> expression_up;
  88
  89 /* Macros for converting between number of expression elements and bytes
  90    to store that many expression elements.  */
  91
  92 #define EXP_ELEM_TO_BYTES(elements) \
  93     ((elements) * sizeof (union exp_element))
  94 #define BYTES_TO_EXP_ELEM(bytes) \
  95     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
  96
  97 /* From parse.c */
  98
  99 extern expression_up parse_expression (const char *);
 100
 101 extern expression_up parse_expression_with_language (const char *string,
 102                                                      enum language lang);
 103
 104 extern struct type *parse_expression_for_completion (const char *, char **,
 105                                                      enum type_code *);
 106
 107 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 108                                   const struct block *, int);
 109
 110 /* For use by parsers; set if we want to parse an expression and
 111    attempt completion.  */
 112 extern int parse_completion;
 113
 114 /* The innermost context required by the stack and register variables
 115    we've encountered so far.  To use this, set it to NULL, then call
 116    parse_<whatever>, then look at it.  */
 117 extern const struct block *innermost_block;
 118
 119 /* From eval.c */
 120
 121 /* Values of NOSIDE argument to eval_subexp.  */
 122
 123 enum noside
 124   {
 125     EVAL_NORMAL,
 126     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 127     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 128                                    call any functions.  The value
 129                                    returned will have the correct
 130                                    type, and will have an
 131                                    approximately correct lvalue
 132                                    type (inaccuracy: anything that is
 133                                    listed as being in a register in
 134                                    the function in which it was
 135                                    declared will be lval_register).
 136                                    Ideally this would not even read
 137                                    target memory, but currently it
 138                                    does in many situations.  */
 139   };
 140
 141 extern struct value *evaluate_subexp_standard
 142   (struct type *, struct expression *, int *, enum noside);
 143
 144 /* From expprint.c */
 145
 146 extern void print_expression (struct expression *, struct ui_file *);
 147
 148 extern const char *op_name (struct expression *exp, enum exp_opcode opcode);
 149
 150 extern const char *op_string (enum exp_opcode);
 151
 152 extern void dump_raw_expression (struct expression *,
 153                                  struct ui_file *, const char *);
 154 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 155
 156 /* In an OP_RANGE expression, either bound could be empty, indicating
 157    that its value is by default that of the corresponding bound of the
 158    array or string.  So we have four sorts of subrange.  This
 159    enumeration type is to identify this.  */
 160
 161 enum range_type
 162   {
 163     BOTH_BOUND_DEFAULT,         /* "(:)"  */
 164     LOW_BOUND_DEFAULT,          /* "(:high)"  */
 165     HIGH_BOUND_DEFAULT,         /* "(low:)"  */
 166     NONE_BOUND_DEFAULT          /* "(low:high)"  */
 167   };
 168
 169 #endif /* !defined (EXPRESSION_H) */