gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2
   3    Copyright (C) 1986-2020 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 #include "gdbtypes.h"
  24
  25 /* While parsing expressions we need to track the innermost lexical block
  26    that we encounter.  In some situations we need to track the innermost
  27    block just for symbols, and in other situations we want to track the
  28    innermost block for symbols and registers.  These flags are used by the
  29    innermost block tracker to control which blocks we consider for the
  30    innermost block.  These flags can be combined together as needed.  */
  31
  32 enum innermost_block_tracker_type
  33 {
  34   /* Track the innermost block for symbols within an expression.  */
  35   INNERMOST_BLOCK_FOR_SYMBOLS = (1 << 0),
  36
  37   /* Track the innermost block for registers within an expression.  */
  38   INNERMOST_BLOCK_FOR_REGISTERS = (1 << 1)
  39 };
  40 DEF_ENUM_FLAGS_TYPE (enum innermost_block_tracker_type,
  41                      innermost_block_tracker_types);
  42
  43 /* Definitions for saved C expressions.  */
  44
  45 /* An expression is represented as a vector of union exp_element's.
  46    Each exp_element is an opcode, except that some opcodes cause
  47    the following exp_element to be treated as a long or double constant
  48    or as a variable.  The opcodes are obeyed, using a stack for temporaries.
  49    The value is left on the temporary stack at the end.  */
  50
  51 /* When it is necessary to include a string,
  52    it can occupy as many exp_elements as it needs.
  53    We find the length of the string using strlen,
  54    divide to find out how many exp_elements are used up,
  55    and skip that many.  Strings, like numbers, are indicated
  56    by the preceding opcode.  */
  57
  58 enum exp_opcode : uint8_t
  59   {
  60 #define OP(name) name ,
  61
  62 #include "std-operator.def"
  63
  64     /* First extension operator.  Individual language modules define extra
  65        operators in *.def include files below with numbers higher than
  66        OP_EXTENDED0.  */
  67     OP (OP_EXTENDED0)
  68
  69 /* Language specific operators.  */
  70 #include "ada-operator.def"
  71 #include "fortran-operator.def"
  72
  73 #undef OP
  74
  75     /* Existing only to swallow the last comma (',') from last .inc file.  */
  76     OP_UNUSED_LAST
  77   };
  78
  79 union exp_element
  80   {
  81     enum exp_opcode opcode;
  82     struct symbol *symbol;
  83     struct minimal_symbol *msymbol;
  84     LONGEST longconst;
  85     gdb_byte floatconst[16];
  86     /* Really sizeof (union exp_element) characters (or less for the last
  87        element of a string).  */
  88     char string;
  89     struct type *type;
  90     struct internalvar *internalvar;
  91     const struct block *block;
  92     struct objfile *objfile;
  93   };
  94
  95 struct expression
  96   {
  97     const struct language_defn *language_defn;  /* language it was
  98                                                    entered in.  */
  99     struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
 100     int nelts;
 101     union exp_element elts[1];
 102   };
 103
 104 typedef gdb::unique_xmalloc_ptr<expression> expression_up;
 105
 106 /* Macros for converting between number of expression elements and bytes
 107    to store that many expression elements.  */
 108
 109 #define EXP_ELEM_TO_BYTES(elements) \
 110     ((elements) * sizeof (union exp_element))
 111 #define BYTES_TO_EXP_ELEM(bytes) \
 112     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 113
 114 /* From parse.c */
 115
 116 class innermost_block_tracker;
 117 extern expression_up parse_expression (const char *,
 118                                        innermost_block_tracker * = nullptr);
 119
 120 extern expression_up parse_expression_with_language (const char *string,
 121                                                      enum language lang);
 122
 123 extern struct type *parse_expression_for_completion
 124     (const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
 125
 126 class innermost_block_tracker;
 127 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 128                                   const struct block *, int,
 129                                   innermost_block_tracker * = nullptr);
 130
 131 /* From eval.c */
 132
 133 /* Values of NOSIDE argument to eval_subexp.  */
 134
 135 enum noside
 136   {
 137     EVAL_NORMAL,
 138     EVAL_SKIP,                  /* Only effect is to increment pos.
 139                                    Return type information where
 140                                    possible.  */
 141     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 142                                    call any functions.  The value
 143                                    returned will have the correct
 144                                    type, and will have an
 145                                    approximately correct lvalue
 146                                    type (inaccuracy: anything that is
 147                                    listed as being in a register in
 148                                    the function in which it was
 149                                    declared will be lval_register).
 150                                    Ideally this would not even read
 151                                    target memory, but currently it
 152                                    does in many situations.  */
 153   };
 154
 155 extern struct value *evaluate_subexp_standard
 156   (struct type *, struct expression *, int *, enum noside);
 157
 158 /* From expprint.c */
 159
 160 extern void print_expression (struct expression *, struct ui_file *);
 161
 162 extern const char *op_name (struct expression *exp, enum exp_opcode opcode);
 163
 164 extern const char *op_string (enum exp_opcode);
 165
 166 extern void dump_raw_expression (struct expression *,
 167                                  struct ui_file *, const char *);
 168 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 169
 170 /* In an OP_RANGE expression, either bound could be empty, indicating
 171    that its value is by default that of the corresponding bound of the
 172    array or string.  Also, the upper end of the range can be exclusive
 173    or inclusive.  So we have six sorts of subrange.  This enumeration
 174    type is to identify this.  */
 175
 176 enum range_type
 177 {
 178   /* Neither the low nor the high bound was given -- so this refers to
 179      the entire available range.  */
 180   BOTH_BOUND_DEFAULT,
 181   /* The low bound was not given and the high bound is inclusive.  */
 182   LOW_BOUND_DEFAULT,
 183   /* The high bound was not given and the low bound in inclusive.  */
 184   HIGH_BOUND_DEFAULT,
 185   /* Both bounds were given and both are inclusive.  */
 186   NONE_BOUND_DEFAULT,
 187   /* The low bound was not given and the high bound is exclusive.  */
 188   NONE_BOUND_DEFAULT_EXCLUSIVE,
 189   /* Both bounds were given.  The low bound is inclusive and the high
 190      bound is exclusive.  */
 191   LOW_BOUND_DEFAULT_EXCLUSIVE,
 192 };
 193
 194 #endif /* !defined (EXPRESSION_H) */