gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2    Copyright 1986, 1989, 1992, 1994 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  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   /* 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
  51   BINOP_ADD,            /* + */
  52   BINOP_SUB,            /* - */
  53   BINOP_MUL,            /* * */
  54   BINOP_DIV,            /* / */
  55   BINOP_REM,            /* % */
  56   BINOP_MOD,            /* mod (Knuth 1.2.4) */
  57   BINOP_LSH,            /* << */
  58   BINOP_RSH,            /* >> */
  59   BINOP_LOGICAL_AND,    /* && */
  60   BINOP_LOGICAL_OR,     /* || */
  61   BINOP_BITWISE_AND,    /* & */
  62   BINOP_BITWISE_IOR,    /* | */
  63   BINOP_BITWISE_XOR,    /* ^ */
  64   BINOP_EQUAL,          /* == */
  65   BINOP_NOTEQUAL,       /* != */
  66   BINOP_LESS,           /* < */
  67   BINOP_GTR,            /* > */
  68   BINOP_LEQ,            /* <= */
  69   BINOP_GEQ,            /* >= */
  70   BINOP_REPEAT,         /* @ */
  71   BINOP_ASSIGN,         /* = */
  72   BINOP_COMMA,          /* , */
  73   BINOP_SUBSCRIPT,      /* x[y] */
  74   BINOP_EXP,            /* Exponentiation */
  75
  76   /* C++.  */
  77
  78   BINOP_MIN,            /* <? */
  79   BINOP_MAX,            /* >? */
  80   BINOP_SCOPE,          /* :: */
  81
  82   /* STRUCTOP_MEMBER is used for pointer-to-member constructs.
  83      X . * Y translates into X STRUCTOP_MEMBER Y.  */
  84   STRUCTOP_MEMBER,
  85
  86   /* STRUCTOP_MPTR is used for pointer-to-member constructs
  87      when X is a pointer instead of an aggregate.  */
  88   STRUCTOP_MPTR,
  89
  90   /* end of C++.  */
  91
  92   /* For Modula-2 integer division DIV */
  93   BINOP_INTDIV,
  94
  95   BINOP_ASSIGN_MODIFY,  /* +=, -=, *=, and so on.
  96                            The following exp_element is another opcode,
  97                            a BINOP_, saying how to modify.
  98                            Then comes another BINOP_ASSIGN_MODIFY,
  99                            making three exp_elements in total.  */
 100
 101   /* Modula-2 standard (binary) procedures */
 102   BINOP_VAL,
 103   BINOP_INCL,
 104   BINOP_EXCL,
 105
 106   /* Concatenate two operands, such as character strings or bitstrings.
 107      If the first operand is a integer expression, then it means concatenate
 108      the second operand with itself that many times. */
 109   BINOP_CONCAT,
 110
 111   /* For Chill and Pascal. */
 112   BINOP_IN, /* Returns 1 iff ARG1 IN ARG2. */
 113
 114   /* This is the "colon operator" used various places in Chill. */
 115   BINOP_RANGE,
 116
 117   /* This must be the highest BINOP_ value, for expprint.c.  */
 118   BINOP_END,
 119
 120   /* Operates on three values computed by following subexpressions.  */
 121   TERNOP_COND,          /* ?: */
 122
 123   /* A sub-string/sub-array.  Chill syntax:  OP1(OP2:OP3).
 124      Return elements OP2 through OP3 of OP1.  */
 125   TERNOP_SLICE,
 126
 127   /* A sub-string/sub-array.  Chill syntax:  OP1(OP2 UP OP3).
 128      Return OP3 elements of OP1, starting with element OP2. */
 129   TERNOP_SLICE_COUNT,
 130
 131   /* Multidimensional subscript operator, such as Modula-2 x[a,b,...].
 132      The dimensionality is encoded in the operator, like the number of
 133      function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>.
 134      The value of the first following subexpression is subscripted
 135      by each of the next following subexpressions, one per dimension. */
 136    MULTI_SUBSCRIPT,
 137
 138   /* The OP_... series take immediate following arguments.
 139      After the arguments come another OP_... (the same one)
 140      so that the grouping can be recognized from the end.  */
 141
 142   /* OP_LONG is followed by a type pointer in the next exp_element
 143      and the long constant value in the following exp_element.
 144      Then comes another OP_LONG.
 145      Thus, the operation occupies four exp_elements.  */
 146   OP_LONG,
 147
 148   /* OP_DOUBLE is similar but takes a DOUBLEST constant instead of a long.  */
 149   OP_DOUBLE,
 150
 151   /* OP_VAR_VALUE takes one struct block * in the following element,
 152      and one struct symbol * in the following exp_element, followed by
 153      another OP_VAR_VALUE, making four exp_elements.  If the block is
 154      non-NULL, evaluate the symbol relative to the innermost frame
 155      executing in that block; if the block is NULL use the selected frame.  */
 156   OP_VAR_VALUE,
 157
 158   /* OP_LAST is followed by an integer in the next exp_element.
 159      The integer is zero for the last value printed,
 160      or it is the absolute number of a history element.
 161      With another OP_LAST at the end, this makes three exp_elements.  */
 162   OP_LAST,
 163
 164   /* OP_REGISTER is followed by an integer in the next exp_element.
 165      This is the number of a register to fetch (as an int).
 166      With another OP_REGISTER at the end, this makes three exp_elements.  */
 167   OP_REGISTER,
 168
 169   /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
 170      With another OP_INTERNALVAR at the end, this makes three exp_elements.  */
 171   OP_INTERNALVAR,
 172
 173   /* OP_FUNCALL is followed by an integer in the next exp_element.
 174      The integer is the number of args to the function call.
 175      That many plus one values from following subexpressions
 176      are used, the first one being the function.
 177      The integer is followed by a repeat of OP_FUNCALL,
 178      making three exp_elements.  */
 179   OP_FUNCALL,
 180
 181   /* This is EXACTLY like OP_FUNCALL but is semantically different.
 182      In F77, array subscript expressions, substring expressions
 183      and function calls are  all exactly the same syntactically. They may
 184      only be dismabiguated at runtime.  Thus this operator, which
 185      indicates that we have found something of the form <name> ( <stuff> ) */
 186   OP_F77_UNDETERMINED_ARGLIST,
 187
 188   /* The following OP is a special one, it introduces a F77 complex
 189      literal. It is followed by exactly two args that are doubles.  */
 190   OP_COMPLEX,
 191
 192   /* OP_STRING represents a string constant.
 193      Its format is the same as that of a STRUCTOP, but the string
 194      data is just made into a string constant when the operation
 195      is executed.  */
 196   OP_STRING,
 197
 198   /* OP_BITSTRING represents a packed bitstring constant.
 199      Its format is the same as that of a STRUCTOP, but the bitstring
 200      data is just made into a bitstring constant when the operation
 201      is executed.  */
 202   OP_BITSTRING,
 203
 204   /* OP_ARRAY creates an array constant out of the following subexpressions.
 205      It is followed by two exp_elements, the first containing an integer
 206      that is the lower bound of the array and the second containing another
 207      integer that is the upper bound of the array.  The second integer is
 208      followed by a repeat of OP_ARRAY, making four exp_elements total.
 209      The bounds are used to compute the number of following subexpressions
 210      to consume, as well as setting the bounds in the created array constant.
 211      The type of the elements is taken from the type of the first subexp,
 212      and they must all match. */
 213   OP_ARRAY,
 214
 215   /* UNOP_CAST is followed by a type pointer in the next exp_element.
 216      With another UNOP_CAST at the end, this makes three exp_elements.
 217      It casts the value of the following subexpression.  */
 218   UNOP_CAST,
 219
 220   /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
 221      With another UNOP_MEMVAL at the end, this makes three exp_elements.
 222      It casts the contents of the word addressed by the value of the
 223      following subexpression.  */
 224   UNOP_MEMVAL,
 225
 226   /* UNOP_... operate on one value from a following subexpression
 227      and replace it with a result.  They take no immediate arguments.  */
 228
 229   UNOP_NEG,             /* Unary - */
 230   UNOP_LOGICAL_NOT,     /* Unary ! */
 231   UNOP_COMPLEMENT,      /* Unary ~ */
 232   UNOP_IND,             /* Unary * */
 233   UNOP_ADDR,            /* Unary & */
 234   UNOP_PREINCREMENT,    /* ++ before an expression */
 235   UNOP_POSTINCREMENT,   /* ++ after an expression */
 236   UNOP_PREDECREMENT,    /* -- before an expression */
 237   UNOP_POSTDECREMENT,   /* -- after an expression */
 238   UNOP_SIZEOF,          /* Unary sizeof (followed by expression) */
 239
 240   UNOP_PLUS,            /* Unary plus */
 241
 242   UNOP_CAP,             /* Modula-2 standard (unary) procedures */
 243   UNOP_CHR,
 244   UNOP_ORD,
 245   UNOP_ABS,
 246   UNOP_FLOAT,
 247   UNOP_HIGH,
 248   UNOP_MAX,
 249   UNOP_MIN,
 250   UNOP_ODD,
 251   UNOP_TRUNC,
 252
 253   /* Chill builtin functions. */
 254   UNOP_LOWER, UNOP_UPPER, UNOP_LENGTH, UNOP_CARD, UNOP_CHMAX, UNOP_CHMIN,
 255
 256   OP_BOOL,              /* Modula-2 builtin BOOLEAN type */
 257   OP_M2_STRING,         /* Modula-2 string constants */
 258
 259   /* STRUCTOP_... operate on a value from a following subexpression
 260      by extracting a structure component specified by a string
 261      that appears in the following exp_elements (as many as needed).
 262      STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
 263      They differ only in the error message given in case the value is
 264      not suitable or the structure component specified is not found.
 265
 266      The length of the string follows the opcode, followed by
 267      BYTES_TO_EXP_ELEM(length) elements containing the data of the
 268      string, followed by the length again and the opcode again.  */
 269
 270   STRUCTOP_STRUCT,
 271   STRUCTOP_PTR,
 272
 273   /* C++ */
 274   /* OP_THIS is just a placeholder for the class instance variable.
 275      It just comes in a tight (OP_THIS, OP_THIS) pair.  */
 276   OP_THIS,
 277
 278   /* OP_SCOPE surrounds a type name and a field name.  The type
 279      name is encoded as one element, but the field name stays as
 280      a string, which, of course, is variable length.  */
 281   OP_SCOPE,
 282
 283   /* Used to represent named structure field values in brace initializers
 284      (or tuples as they are called in Chill).
 285      The gcc C syntax is NAME:VALUE or .NAME=VALUE, the Chill syntax is
 286      .NAME:VALUE.  Multiple labels (as in the Chill syntax
 287      .NAME1,.NAME2:VALUE) is represented as if it were
 288      .NAME1:(.NAME2:VALUE) (though that is not valid Chill syntax).
 289
 290      The NAME is represented as for STRUCTOP_STRUCT;  VALUE follows. */
 291   OP_LABELED,
 292
 293   /* OP_TYPE is for parsing types, and used with the "ptype" command
 294      so we can look up types that are qualified by scope, either with
 295      the GDB "::" operator, or the Modula-2 '.' operator. */
 296   OP_TYPE,
 297
 298   /* An un-looked-up identifier. */
 299   OP_NAME,
 300
 301   /* An unparsed expression.  Used for Scheme (for now at least) */
 302   OP_EXPRSTRING
 303 };
 304
 305 union exp_element
 306 {
 307   enum exp_opcode opcode;
 308   struct symbol *symbol;
 309   LONGEST longconst;
 310   DOUBLEST doubleconst;
 311   /* Really sizeof (union exp_element) characters (or less for the last
 312      element of a string).  */
 313   char string;
 314   struct type *type;
 315   struct internalvar *internalvar;
 316   struct block *block;
 317 };
 318
 319 struct expression
 320 {
 321   const struct language_defn *language_defn;  /* language it was entered in */
 322   int nelts;
 323   union exp_element elts[1];
 324 };
 325
 326 /* Macros for converting between number of expression elements and bytes
 327    to store that many expression elements. */
 328
 329 #define EXP_ELEM_TO_BYTES(elements) \
 330     ((elements) * sizeof (union exp_element))
 331 #define BYTES_TO_EXP_ELEM(bytes) \
 332     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 333
 334 /* From parse.c */
 335
 336 extern struct expression *parse_expression PARAMS ((char *));
 337
 338 extern struct expression *parse_exp_1 PARAMS ((char **, struct block *, int));
 339
 340 /* The innermost context required by the stack and register variables
 341    we've encountered so far.  To use this, set it to NULL, then call
 342    parse_<whatever>, then look at it.  */
 343 extern struct block *innermost_block;
 344
 345 /* From eval.c */
 346
 347 /* Values of NOSIDE argument to eval_subexp.  */
 348
 349 enum noside
 350 {
 351   EVAL_NORMAL,
 352   EVAL_SKIP,                    /* Only effect is to increment pos.  */
 353   EVAL_AVOID_SIDE_EFFECTS       /* Don't modify any variables or
 354                                    call any functions.  The value
 355                                    returned will have the correct
 356                                    type, and will have an
 357                                    approximately correct lvalue
 358                                    type (inaccuracy: anything that is
 359                                    listed as being in a register in
 360                                    the function in which it was
 361                                    declared will be lval_register).  */
 362 };
 363
 364 extern struct value* evaluate_subexp_standard
 365 PARAMS ((struct type *, struct expression *, int*, enum noside));
 366
 367 /* From expprint.c */
 368
 369 extern void print_expression PARAMS ((struct expression *, GDB_FILE *));
 370
 371 extern char *op_string PARAMS ((enum exp_opcode));
 372
 373 #ifdef MAINTENANCE_CMDS
 374 extern void dump_prefix_expression PARAMS ((struct expression *,
 375                                             GDB_FILE *,
 376                                             char *));
 377 extern void dump_postfix_expression PARAMS ((struct expression *,
 378                                              GDB_FILE *,
 379                                              char *));
 380 #endif /* MAINTENANCE_CMDS */
 381
 382 #endif  /* !defined (EXPRESSION_H) */