gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2    Copyright 1986, 1989, 1992 Free Software Foundation, Inc.
   3
   4 This file is part of GDB.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 #if !defined (EXPRESSION_H)
  21 #define EXPRESSION_H 1
  22
  23 #ifdef __STDC__
  24 struct block;   /* Forward declaration for prototypes */
  25 #endif
  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   /* Used when it's necessary to pass an opcode which will be ignored,
  45      or to catch uninitialized values.  */
  46   OP_NULL,
  47
  48 /* BINOP_... operate on two values computed by following subexpressions,
  49    replacing them by one result value.  They take no immediate arguments.  */
  50   BINOP_ADD,            /* + */
  51   BINOP_SUB,            /* - */
  52   BINOP_MUL,            /* * */
  53   BINOP_DIV,            /* / */
  54   BINOP_REM,            /* % */
  55   BINOP_LSH,            /* << */
  56   BINOP_RSH,            /* >> */
  57   BINOP_LOGICAL_AND,    /* && */
  58   BINOP_LOGICAL_OR,     /* || */
  59   BINOP_BITWISE_AND,    /* & */
  60   BINOP_BITWISE_IOR,    /* | */
  61   BINOP_BITWISE_XOR,    /* ^ */
  62   BINOP_EQUAL,          /* == */
  63   BINOP_NOTEQUAL,       /* != */
  64   BINOP_LESS,           /* < */
  65   BINOP_GTR,            /* > */
  66   BINOP_LEQ,            /* <= */
  67   BINOP_GEQ,            /* >= */
  68   BINOP_REPEAT,         /* @ */
  69   BINOP_ASSIGN,         /* = */
  70   BINOP_COMMA,          /* , */
  71   BINOP_SUBSCRIPT,      /* x[y] */
  72   BINOP_EXP,            /* Exponentiation */
  73
  74 /* C++.  */
  75   BINOP_MIN,            /* <? */
  76   BINOP_MAX,            /* >? */
  77   BINOP_SCOPE,          /* :: */
  78
  79   /* STRUCTOP_MEMBER is used for pointer-to-member constructs.
  80      X . * Y translates into X STRUCTOP_MEMBER Y.  */
  81   STRUCTOP_MEMBER,
  82   /* STRUCTOP_MPTR is used for pointer-to-member constructs
  83      when X is a pointer instead of an aggregate.  */
  84   STRUCTOP_MPTR,
  85 /* end of C++.  */
  86
  87   /* For Modula-2 integer division DIV */
  88   BINOP_INTDIV,
  89
  90   BINOP_ASSIGN_MODIFY,  /* +=, -=, *=, and so on.
  91                            The following exp_element is another opcode,
  92                            a BINOP_, saying how to modify.
  93                            Then comes another BINOP_ASSIGN_MODIFY,
  94                            making three exp_elements in total.  */
  95
  96   /* Modula-2 standard (binary) procedures*/
  97   BINOP_VAL,
  98   BINOP_INCL,
  99   BINOP_EXCL,
 100
 101   /* This must be the highest BINOP_ value, for expprint.c.  */
 102   BINOP_END,
 103
 104 /* Operates on three values computed by following subexpressions.  */
 105   TERNOP_COND,          /* ?: */
 106
 107 /* Multidimensional subscript operator, such as Modula-2 x[a,b,...].
 108    The dimensionality is encoded in the operator, like the number of
 109    function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>.
 110    The value of the first following subexpression is subscripted
 111    by each of the next following subexpressions, one per dimension. */
 112
 113    MULTI_SUBSCRIPT,
 114
 115 /* The OP_... series take immediate following arguments.
 116    After the arguments come another OP_... (the same one)
 117    so that the grouping can be recognized from the end.  */
 118
 119 /* OP_LONG is followed by a type pointer in the next exp_element
 120    and the long constant value in the following exp_element.
 121    Then comes another OP_LONG.
 122    Thus, the operation occupies four exp_elements.  */
 123
 124   OP_LONG,
 125 /* OP_DOUBLE is similar but takes a double constant instead of a long one.  */
 126   OP_DOUBLE,
 127 /* OP_VAR_VALUE takes one struct symbol * in the following exp_element,
 128    followed by another OP_VAR_VALUE, making three exp_elements.  */
 129   OP_VAR_VALUE,
 130 /* OP_LAST is followed by an integer in the next exp_element.
 131    The integer is zero for the last value printed,
 132    or it is the absolute number of a history element.
 133    With another OP_LAST at the end, this makes three exp_elements.  */
 134   OP_LAST,
 135 /* OP_REGISTER is followed by an integer in the next exp_element.
 136    This is the number of a register to fetch (as an int).
 137    With another OP_REGISTER at the end, this makes three exp_elements.  */
 138   OP_REGISTER,
 139 /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
 140    With another OP_INTERNALVAR at the end, this makes three exp_elements.  */
 141   OP_INTERNALVAR,
 142 /* OP_FUNCALL is followed by an integer in the next exp_element.
 143    The integer is the number of args to the function call.
 144    That many plus one values from following subexpressions
 145    are used, the first one being the function.
 146    The integer is followed by a repeat of OP_FUNCALL,
 147    making three exp_elements.  */
 148   OP_FUNCALL,
 149 /* OP_STRING represents a string constant.
 150    Its format is the same as that of a STRUCTOP, but the string
 151    data is just made into a string constant when the operation
 152    is executed.  */
 153   OP_STRING,
 154
 155 /* UNOP_CAST is followed by a type pointer in the next exp_element.
 156    With another UNOP_CAST at the end, this makes three exp_elements.
 157    It casts the value of the following subexpression.  */
 158   UNOP_CAST,
 159 /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
 160    With another UNOP_MEMVAL at the end, this makes three exp_elements.
 161    It casts the contents of the word addressed by the value of the
 162    following subexpression.  */
 163   UNOP_MEMVAL,
 164 /* UNOP_... operate on one value from a following subexpression
 165    and replace it with a result.  They take no immediate arguments.  */
 166   UNOP_NEG,             /* Unary - */
 167   UNOP_LOGICAL_NOT,     /* Unary ! */
 168   UNOP_COMPLEMENT,      /* Unary ~ */
 169   UNOP_IND,             /* Unary * */
 170   UNOP_ADDR,            /* Unary & */
 171   UNOP_PREINCREMENT,    /* ++ before an expression */
 172   UNOP_POSTINCREMENT,   /* ++ after an expression */
 173   UNOP_PREDECREMENT,    /* -- before an expression */
 174   UNOP_POSTDECREMENT,   /* -- after an expression */
 175   UNOP_SIZEOF,          /* Unary sizeof (followed by expression) */
 176
 177   UNOP_PLUS,            /* Unary plus */
 178
 179   UNOP_CAP,             /* Modula-2 standard (unary) procedures */
 180   UNOP_CHR,
 181   UNOP_ORD,
 182   UNOP_ABS,
 183   UNOP_FLOAT,
 184   UNOP_HIGH,
 185   UNOP_MAX,
 186   UNOP_MIN,
 187   UNOP_ODD,
 188   UNOP_TRUNC,
 189
 190   OP_BOOL,              /* Modula-2 builtin BOOLEAN type */
 191   OP_M2_STRING,         /* Modula-2 string constants */
 192
 193 /* STRUCTOP_... operate on a value from a following subexpression
 194    by extracting a structure component specified by a string
 195    that appears in the following exp_elements (as many as needed).
 196    STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
 197    They differ only in the error message given in case the value is
 198    not suitable or the structure component specified is not found.
 199
 200    The length of the string follows in the next exp_element,
 201    (after the string), followed by another STRUCTOP_... code.  */
 202   STRUCTOP_STRUCT,
 203   STRUCTOP_PTR,
 204
 205 /* C++ */
 206   /* OP_THIS is just a placeholder for the class instance variable.
 207      It just comes in a tight (OP_THIS, OP_THIS) pair.  */
 208   OP_THIS,
 209
 210   /* OP_SCOPE surrounds a type name and a field name.  The type
 211      name is encoded as one element, but the field name stays as
 212      a string, which, of course, is variable length.  */
 213   OP_SCOPE,
 214
 215   /* OP_TYPE is for parsing types, and used with the "ptype" command
 216      so we can look up types that are qualified by scope, either with
 217      the GDB "::" operator, or the Modula-2 '.' operator. */
 218   OP_TYPE
 219 };
 220
 221 union exp_element
 222 {
 223   enum exp_opcode opcode;
 224   struct symbol *symbol;
 225   LONGEST longconst;
 226   double doubleconst;
 227   char string;
 228   struct type *type;
 229   struct internalvar *internalvar;
 230 };
 231
 232 struct expression
 233 {
 234   const struct language_defn *language_defn;  /* language it was entered in */
 235   int nelts;
 236   union exp_element elts[1];
 237 };
 238
 239 /* From parse.c */
 240
 241 extern struct expression *
 242 parse_expression PARAMS ((char *));
 243
 244 extern struct expression *
 245 parse_exp_1 PARAMS ((char **, struct block *, int));
 246
 247 /* The innermost context required by the stack and register variables
 248    we've encountered so far.  To use this, set it to NULL, then call
 249    parse_<whatever>, then look at it.  */
 250 extern struct block *innermost_block;
 251
 252 /* From expprint.c */
 253
 254 extern void
 255 print_expression PARAMS ((struct expression *, FILE *));
 256
 257 extern char *
 258 op_string PARAMS ((enum exp_opcode));
 259
 260 /* To enable dumping of all parsed expressions in a human readable
 261    form, define DEBUG_EXPRESSIONS.  This is a compile time constant
 262    at the moment, since it's not clear that this feature is important
 263    enough to include by default. */
 264
 265 #ifdef DEBUG_EXPRESSIONS
 266 extern void
 267 dump_expression PARAMS ((struct expression *, FILE *, char *));
 268 #define DUMP_EXPRESSION(exp,file,note) dump_expression ((exp), (file), (note))
 269 #else
 270 #define DUMP_EXPRESSION(exp,file,note)  /* Null expansion */
 271 #endif  /* DEBUG_EXPRESSIONS */
 272
 273 #endif  /* !defined (EXPRESSION_H) */