gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2
   3    Copyright (C) 1986-2019 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 /* While parsing expressions we need to track the innermost lexical block
  24    that we encounter.  In some situations we need to track the innermost
  25    block just for symbols, and in other situations we want to track the
  26    innermost block for symbols and registers.  These flags are used by the
  27    innermost block tracker to control which blocks we consider for the
  28    innermost block.  These flags can be combined together as needed.  */
  29
  30 enum innermost_block_tracker_type
  31 {
  32   /* Track the innermost block for symbols within an expression.  */
  33   INNERMOST_BLOCK_FOR_SYMBOLS = (1 << 0),
  34
  35   /* Track the innermost block for registers within an expression.  */
  36   INNERMOST_BLOCK_FOR_REGISTERS = (1 << 1)
  37 };
  38 DEF_ENUM_FLAGS_TYPE (enum innermost_block_tracker_type,
  39                      innermost_block_tracker_types);
  40
  41 /* Definitions for saved C expressions.  */
  42
  43 /* An expression is represented as a vector of union exp_element's.
  44    Each exp_element is an opcode, except that some opcodes cause
  45    the following exp_element to be treated as a long or double constant
  46    or as a variable.  The opcodes are obeyed, using a stack for temporaries.
  47    The value is left on the temporary stack at the end.  */
  48
  49 /* When it is necessary to include a string,
  50    it can occupy as many exp_elements as it needs.
  51    We find the length of the string using strlen,
  52    divide to find out how many exp_elements are used up,
  53    and skip that many.  Strings, like numbers, are indicated
  54    by the preceding opcode.  */
  55
  56 enum exp_opcode : uint8_t
  57   {
  58 #define OP(name) name ,
  59
  60 #include "std-operator.def"
  61
  62     /* First extension operator.  Individual language modules define extra
  63        operators in *.def include files below with numbers higher than
  64        OP_EXTENDED0.  */
  65     OP (OP_EXTENDED0)
  66
  67 /* Language specific operators.  */
  68 #include "ada-operator.def"
  69
  70 #undef OP
  71
  72     /* Existing only to swallow the last comma (',') from last .inc file.  */
  73     OP_UNUSED_LAST
  74   };
  75
  76 union exp_element
  77   {
  78     enum exp_opcode opcode;
  79     struct symbol *symbol;
  80     struct minimal_symbol *msymbol;
  81     LONGEST longconst;
  82     gdb_byte floatconst[16];
  83     /* Really sizeof (union exp_element) characters (or less for the last
  84        element of a string).  */
  85     char string;
  86     struct type *type;
  87     struct internalvar *internalvar;
  88     const struct block *block;
  89     struct objfile *objfile;
  90   };
  91
  92 struct expression
  93   {
  94     const struct language_defn *language_defn;  /* language it was
  95                                                    entered in.  */
  96     struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
  97     int nelts;
  98     union exp_element elts[1];
  99   };
 100
 101 typedef gdb::unique_xmalloc_ptr<expression> expression_up;
 102
 103 /* Macros for converting between number of expression elements and bytes
 104    to store that many expression elements.  */
 105
 106 #define EXP_ELEM_TO_BYTES(elements) \
 107     ((elements) * sizeof (union exp_element))
 108 #define BYTES_TO_EXP_ELEM(bytes) \
 109     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 110
 111 /* From parse.c */
 112
 113 extern expression_up parse_expression (const char *);
 114
 115 extern expression_up parse_expression_with_language (const char *string,
 116                                                      enum language lang);
 117
 118 extern struct type *parse_expression_for_completion
 119     (const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
 120
 121 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 122                                   const struct block *, int,
 123                                   innermost_block_tracker_types
 124                                     = INNERMOST_BLOCK_FOR_SYMBOLS);
 125
 126 /* For use by parsers; set if we want to parse an expression and
 127    attempt completion.  */
 128 extern int parse_completion;
 129
 130 /* From eval.c */
 131
 132 /* Values of NOSIDE argument to eval_subexp.  */
 133
 134 enum noside
 135   {
 136     EVAL_NORMAL,
 137     EVAL_SKIP,                  /* Only effect is to increment pos.
 138                                    Return type information where
 139                                    possible.  */
 140     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 141                                    call any functions.  The value
 142                                    returned will have the correct
 143                                    type, and will have an
 144                                    approximately correct lvalue
 145                                    type (inaccuracy: anything that is
 146                                    listed as being in a register in
 147                                    the function in which it was
 148                                    declared will be lval_register).
 149                                    Ideally this would not even read
 150                                    target memory, but currently it
 151                                    does in many situations.  */
 152   };
 153
 154 extern struct value *evaluate_subexp_standard
 155   (struct type *, struct expression *, int *, enum noside);
 156
 157 /* From expprint.c */
 158
 159 extern void print_expression (struct expression *, struct ui_file *);
 160
 161 extern const char *op_name (struct expression *exp, enum exp_opcode opcode);
 162
 163 extern const char *op_string (enum exp_opcode);
 164
 165 extern void dump_raw_expression (struct expression *,
 166                                  struct ui_file *, const char *);
 167 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 168
 169 /* In an OP_RANGE expression, either bound could be empty, indicating
 170    that its value is by default that of the corresponding bound of the
 171    array or string.  Also, the upper end of the range can be exclusive
 172    or inclusive.  So we have six sorts of subrange.  This enumeration
 173    type is to identify this.  */
 174
 175 enum range_type
 176 {
 177   /* Neither the low nor the high bound was given -- so this refers to
 178      the entire available range.  */
 179   BOTH_BOUND_DEFAULT,
 180   /* The low bound was not given and the high bound is inclusive.  */
 181   LOW_BOUND_DEFAULT,
 182   /* The high bound was not given and the low bound in inclusive.  */
 183   HIGH_BOUND_DEFAULT,
 184   /* Both bounds were given and both are inclusive.  */
 185   NONE_BOUND_DEFAULT,
 186   /* The low bound was not given and the high bound is exclusive.  */
 187   NONE_BOUND_DEFAULT_EXCLUSIVE,
 188   /* Both bounds were given.  The low bound is inclusive and the high
 189      bound is exclusive.  */
 190   LOW_BOUND_DEFAULT_EXCLUSIVE,
 191 };
 192
 193 #endif /* !defined (EXPRESSION_H) */