gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2
   3    Copyright (C) 1986, 1989, 1992, 1994, 2000, 2003, 2005, 2007, 2008, 2009
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #if !defined (EXPRESSION_H)
  22 #define EXPRESSION_H 1
  23
  24
  25 #include "symtab.h"             /* Needed for "struct block" type. */
  26 #include "doublest.h"           /* Needed for DOUBLEST.  */
  27
  28
  29 /* Definitions for saved C expressions.  */
  30
  31 /* An expression is represented as a vector of union exp_element's.
  32    Each exp_element is an opcode, except that some opcodes cause
  33    the following exp_element to be treated as a long or double constant
  34    or as a variable.  The opcodes are obeyed, using a stack for temporaries.
  35    The value is left on the temporary stack at the end.  */
  36
  37 /* When it is necessary to include a string,
  38    it can occupy as many exp_elements as it needs.
  39    We find the length of the string using strlen,
  40    divide to find out how many exp_elements are used up,
  41    and skip that many.  Strings, like numbers, are indicated
  42    by the preceding opcode.  */
  43
  44 enum exp_opcode
  45   {
  46     /* Used when it's necessary to pass an opcode which will be ignored,
  47        or to catch uninitialized values.  */
  48     OP_NULL,
  49
  50 /* BINOP_... operate on two values computed by following subexpressions,
  51    replacing them by one result value.  They take no immediate arguments.  */
  52
  53     BINOP_ADD,                  /* + */
  54     BINOP_SUB,                  /* - */
  55     BINOP_MUL,                  /* * */
  56     BINOP_DIV,                  /* / */
  57     BINOP_REM,                  /* % */
  58     BINOP_MOD,                  /* mod (Knuth 1.2.4) */
  59     BINOP_LSH,                  /* << */
  60     BINOP_RSH,                  /* >> */
  61     BINOP_LOGICAL_AND,          /* && */
  62     BINOP_LOGICAL_OR,           /* || */
  63     BINOP_BITWISE_AND,          /* & */
  64     BINOP_BITWISE_IOR,          /* | */
  65     BINOP_BITWISE_XOR,          /* ^ */
  66     BINOP_EQUAL,                /* == */
  67     BINOP_NOTEQUAL,             /* != */
  68     BINOP_LESS,                 /* < */
  69     BINOP_GTR,                  /* > */
  70     BINOP_LEQ,                  /* <= */
  71     BINOP_GEQ,                  /* >= */
  72     BINOP_REPEAT,               /* @ */
  73     BINOP_ASSIGN,               /* = */
  74     BINOP_COMMA,                /* , */
  75     BINOP_SUBSCRIPT,            /* x[y] */
  76     BINOP_EXP,                  /* Exponentiation */
  77
  78     /* C++.  */
  79
  80     BINOP_MIN,                  /* <? */
  81     BINOP_MAX,                  /* >? */
  82
  83     /* STRUCTOP_MEMBER is used for pointer-to-member constructs.
  84        X . * Y translates into X STRUCTOP_MEMBER Y.  */
  85     STRUCTOP_MEMBER,
  86
  87     /* STRUCTOP_MPTR is used for pointer-to-member constructs
  88        when X is a pointer instead of an aggregate.  */
  89     STRUCTOP_MPTR,
  90
  91     /* TYPE_INSTANCE is used when the user specifies a specific
  92        type instantiation for overloaded methods/functions.
  93
  94        The format is:
  95        TYPE_INSTANCE num_types type0 ... typeN num_types TYPE_INSTANCE  */
  96     TYPE_INSTANCE,
  97
  98     /* end of C++.  */
  99
 100     /* For Modula-2 integer division DIV */
 101     BINOP_INTDIV,
 102
 103     BINOP_ASSIGN_MODIFY,        /* +=, -=, *=, and so on.
 104                                    The following exp_element is another opcode,
 105                                    a BINOP_, saying how to modify.
 106                                    Then comes another BINOP_ASSIGN_MODIFY,
 107                                    making three exp_elements in total.  */
 108
 109     /* Modula-2 standard (binary) procedures */
 110     BINOP_VAL,
 111     BINOP_INCL,
 112     BINOP_EXCL,
 113
 114     /* Concatenate two operands, such as character strings or bitstrings.
 115        If the first operand is a integer expression, then it means concatenate
 116        the second operand with itself that many times. */
 117     BINOP_CONCAT,
 118
 119     /* For (the deleted) Chill and Pascal. */
 120     BINOP_IN,                   /* Returns 1 iff ARG1 IN ARG2. */
 121
 122     /* This is the "colon operator" used various places in (the
 123        deleted) Chill. */
 124     BINOP_RANGE,
 125
 126     /* This must be the highest BINOP_ value, for expprint.c.  */
 127     BINOP_END,
 128
 129     /* Operates on three values computed by following subexpressions.  */
 130     TERNOP_COND,                /* ?: */
 131
 132     /* A sub-string/sub-array.  (the deleted) Chill syntax:
 133        OP1(OP2:OP3).  Return elements OP2 through OP3 of OP1.  */
 134     TERNOP_SLICE,
 135
 136     /* A sub-string/sub-array.  (The deleted) Chill syntax: OP1(OP2 UP
 137        OP3).  Return OP3 elements of OP1, starting with element
 138        OP2. */
 139     TERNOP_SLICE_COUNT,
 140
 141     /* Multidimensional subscript operator, such as Modula-2 x[a,b,...].
 142        The dimensionality is encoded in the operator, like the number of
 143        function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>.
 144        The value of the first following subexpression is subscripted
 145        by each of the next following subexpressions, one per dimension. */
 146     MULTI_SUBSCRIPT,
 147
 148     /* The OP_... series take immediate following arguments.
 149        After the arguments come another OP_... (the same one)
 150        so that the grouping can be recognized from the end.  */
 151
 152     /* OP_LONG is followed by a type pointer in the next exp_element
 153        and the long constant value in the following exp_element.
 154        Then comes another OP_LONG.
 155        Thus, the operation occupies four exp_elements.  */
 156     OP_LONG,
 157
 158     /* OP_DOUBLE is similar but takes a DOUBLEST constant instead of a long.  */
 159     OP_DOUBLE,
 160
 161     /* OP_VAR_VALUE takes one struct block * in the following element,
 162        and one struct symbol * in the following exp_element, followed by
 163        another OP_VAR_VALUE, making four exp_elements.  If the block is
 164        non-NULL, evaluate the symbol relative to the innermost frame
 165        executing in that block; if the block is NULL use the selected frame.  */
 166     OP_VAR_VALUE,
 167
 168     /* OP_LAST is followed by an integer in the next exp_element.
 169        The integer is zero for the last value printed,
 170        or it is the absolute number of a history element.
 171        With another OP_LAST at the end, this makes three exp_elements.  */
 172     OP_LAST,
 173
 174     /* OP_REGISTER is followed by a string in the next exp_element.
 175        This is the name of a register to fetch.  */
 176     OP_REGISTER,
 177
 178     /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
 179        With another OP_INTERNALVAR at the end, this makes three exp_elements.  */
 180     OP_INTERNALVAR,
 181
 182     /* OP_FUNCALL is followed by an integer in the next exp_element.
 183        The integer is the number of args to the function call.
 184        That many plus one values from following subexpressions
 185        are used, the first one being the function.
 186        The integer is followed by a repeat of OP_FUNCALL,
 187        making three exp_elements.  */
 188     OP_FUNCALL,
 189
 190     /* OP_OBJC_MSGCALL is followed by a string in the next exp_element and then an
 191        integer.  The string is the selector string.  The integer is the number
 192        of arguments to the message call.  That many plus one values are used,
 193        the first one being the object pointer.  This is an Objective C message */
 194     OP_OBJC_MSGCALL,
 195
 196     /* This is EXACTLY like OP_FUNCALL but is semantically different.
 197        In F77, array subscript expressions, substring expressions
 198        and function calls are  all exactly the same syntactically. They may
 199        only be disambiguated at runtime.  Thus this operator, which
 200        indicates that we have found something of the form <name> ( <stuff> ) */
 201     OP_F77_UNDETERMINED_ARGLIST,
 202
 203     /* OP_COMPLEX takes a type in the following element, followed by another
 204        OP_COMPLEX, making three exp_elements.  It is followed by two double
 205        args, and converts them into a complex number of the given type. */
 206     OP_COMPLEX,
 207
 208     /* OP_STRING represents a string constant.
 209        Its format is the same as that of a STRUCTOP, but the string
 210        data is just made into a string constant when the operation
 211        is executed.  */
 212     OP_STRING,
 213
 214     /* OP_BITSTRING represents a packed bitstring constant.
 215        Its format is the same as that of a STRUCTOP, but the bitstring
 216        data is just made into a bitstring constant when the operation
 217        is executed.  */
 218     OP_BITSTRING,
 219
 220     /* OP_ARRAY creates an array constant out of the following subexpressions.
 221        It is followed by two exp_elements, the first containing an integer
 222        that is the lower bound of the array and the second containing another
 223        integer that is the upper bound of the array.  The second integer is
 224        followed by a repeat of OP_ARRAY, making four exp_elements total.
 225        The bounds are used to compute the number of following subexpressions
 226        to consume, as well as setting the bounds in the created array constant.
 227        The type of the elements is taken from the type of the first subexp,
 228        and they must all match. */
 229     OP_ARRAY,
 230
 231     /* UNOP_CAST is followed by a type pointer in the next exp_element.
 232        With another UNOP_CAST at the end, this makes three exp_elements.
 233        It casts the value of the following subexpression.  */
 234     UNOP_CAST,
 235
 236     /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
 237        With another UNOP_MEMVAL at the end, this makes three exp_elements.
 238        It casts the contents of the word addressed by the value of the
 239        following subexpression.  */
 240     UNOP_MEMVAL,
 241
 242     /* UNOP_MEMVAL_TLS is followed by a `struct objfile' pointer in the next
 243        exp_element and a type pointer in the following exp_element.
 244        With another UNOP_MEMVAL_TLS at the end, this makes four exp_elements.
 245        It casts the contents of the word offsetted by the value of the
 246        following subexpression from the TLS specified by `struct objfile'.  */
 247     UNOP_MEMVAL_TLS,
 248
 249     /* UNOP_... operate on one value from a following subexpression
 250        and replace it with a result.  They take no immediate arguments.  */
 251
 252     UNOP_NEG,                   /* Unary - */
 253     UNOP_LOGICAL_NOT,           /* Unary ! */
 254     UNOP_COMPLEMENT,            /* Unary ~ */
 255     UNOP_IND,                   /* Unary * */
 256     UNOP_ADDR,                  /* Unary & */
 257     UNOP_PREINCREMENT,          /* ++ before an expression */
 258     UNOP_POSTINCREMENT,         /* ++ after an expression */
 259     UNOP_PREDECREMENT,          /* -- before an expression */
 260     UNOP_POSTDECREMENT,         /* -- after an expression */
 261     UNOP_SIZEOF,                /* Unary sizeof (followed by expression) */
 262
 263     UNOP_PLUS,                  /* Unary plus */
 264
 265     UNOP_CAP,                   /* Modula-2 standard (unary) procedures */
 266     UNOP_CHR,
 267     UNOP_ORD,
 268     UNOP_ABS,
 269     UNOP_FLOAT,
 270     UNOP_HIGH,
 271     UNOP_MAX,
 272     UNOP_MIN,
 273     UNOP_ODD,
 274     UNOP_TRUNC,
 275
 276     /* (The deleted) Chill builtin functions.  */
 277     UNOP_LOWER, UNOP_UPPER, UNOP_LENGTH, UNOP_CARD, UNOP_CHMAX, UNOP_CHMIN,
 278
 279     OP_BOOL,                    /* Modula-2 builtin BOOLEAN type */
 280     OP_M2_STRING,               /* Modula-2 string constants */
 281
 282     /* STRUCTOP_... operate on a value from a following subexpression
 283        by extracting a structure component specified by a string
 284        that appears in the following exp_elements (as many as needed).
 285        STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
 286        They differ only in the error message given in case the value is
 287        not suitable or the structure component specified is not found.
 288
 289        The length of the string follows the opcode, followed by
 290        BYTES_TO_EXP_ELEM(length) elements containing the data of the
 291        string, followed by the length again and the opcode again.  */
 292
 293     STRUCTOP_STRUCT,
 294     STRUCTOP_PTR,
 295
 296     /* C++: OP_THIS is just a placeholder for the class instance variable.
 297        It just comes in a tight (OP_THIS, OP_THIS) pair.  */
 298     OP_THIS,
 299
 300     /* Objective-C: OP_OBJC_SELF is just a placeholder for the class instance
 301        variable.  It just comes in a tight (OP_OBJC_SELF, OP_OBJC_SELF) pair.  */
 302     OP_OBJC_SELF,
 303
 304     /* Objective C: "@selector" pseudo-operator */
 305     OP_OBJC_SELECTOR,
 306
 307     /* OP_SCOPE surrounds a type name and a field name.  The type
 308        name is encoded as one element, but the field name stays as
 309        a string, which, of course, is variable length.  */
 310     OP_SCOPE,
 311
 312     /* Used to represent named structure field values in brace
 313        initializers (or tuples as they are called in (the deleted)
 314        Chill).
 315
 316        The gcc C syntax is NAME:VALUE or .NAME=VALUE, the (the
 317        deleted) Chill syntax is .NAME:VALUE.  Multiple labels (as in
 318        the (the deleted) Chill syntax .NAME1,.NAME2:VALUE) is
 319        represented as if it were .NAME1:(.NAME2:VALUE) (though that is
 320        not valid (the deleted) Chill syntax).
 321
 322        The NAME is represented as for STRUCTOP_STRUCT;  VALUE follows. */
 323     OP_LABELED,
 324
 325     /* OP_TYPE is for parsing types, and used with the "ptype" command
 326        so we can look up types that are qualified by scope, either with
 327        the GDB "::" operator, or the Modula-2 '.' operator. */
 328     OP_TYPE,
 329
 330     /* An un-looked-up identifier. */
 331     OP_NAME,
 332
 333     /* An Objective C Foundation Class NSString constant */
 334     OP_OBJC_NSSTRING,
 335
 336     /* A F90 array range operator (for "exp:exp", "exp:", ":exp" and ":").  */
 337     OP_F90_RANGE,
 338
 339     /* OP_DECFLOAT is followed by a type pointer in the next exp_element
 340        and a dec long constant value in the following exp_element.
 341        Then comes another OP_DECFLOAT.  */
 342     OP_DECFLOAT,
 343
 344      /* First extension operator.  Individual language modules define
 345         extra operators in *.inc include files below always starting with
 346         numbering at OP_EXTENDED0:
 347              BINOP_MOGRIFY = OP_EXTENDED0,
 348              BINOP_FROB,
 349              ...  */
 350     OP_EXTENDED0,
 351
 352     /* Last possible extension operator.  Defined to provide an
 353        explicit and finite number of extended operators. */
 354     OP_EXTENDED_LAST = 0xff,
 355     /* NOTE: Eventually, we expect to convert to an object-oriented
 356        formulation for expression operators that does away with the
 357        need for these extension operators, and indeed for this
 358        entire enumeration type.  Therefore, consider the OP_EXTENDED
 359        definitions to be a temporary measure. */
 360
 361     /* Each language specific set of operators starts at OP_EXTENDED0.  */
 362 #include "ada-operator.inc"
 363
 364     /* Existing only to swallow the last comma (',') from last .inc file.  */
 365     OP_UNUSED_LAST
 366   };
 367
 368 union exp_element
 369   {
 370     enum exp_opcode opcode;
 371     struct symbol *symbol;
 372     LONGEST longconst;
 373     DOUBLEST doubleconst;
 374     gdb_byte decfloatconst[16];
 375     /* Really sizeof (union exp_element) characters (or less for the last
 376        element of a string).  */
 377     char string;
 378     struct type *type;
 379     struct internalvar *internalvar;
 380     struct block *block;
 381     struct objfile *objfile;
 382   };
 383
 384 struct expression
 385   {
 386     const struct language_defn *language_defn;  /* language it was entered in */
 387     struct gdbarch *gdbarch;  /* architecture it was parsed in */
 388     int nelts;
 389     union exp_element elts[1];
 390   };
 391
 392 /* Macros for converting between number of expression elements and bytes
 393    to store that many expression elements. */
 394
 395 #define EXP_ELEM_TO_BYTES(elements) \
 396     ((elements) * sizeof (union exp_element))
 397 #define BYTES_TO_EXP_ELEM(bytes) \
 398     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 399
 400 /* From parse.c */
 401
 402 extern struct expression *parse_expression (char *);
 403
 404 extern struct type *parse_field_expression (char *, char **);
 405
 406 extern struct expression *parse_exp_1 (char **, struct block *, int);
 407
 408 /* For use by parsers; set if we want to parse an expression and
 409    attempt to complete a field name.  */
 410 extern int in_parse_field;
 411
 412 /* The innermost context required by the stack and register variables
 413    we've encountered so far.  To use this, set it to NULL, then call
 414    parse_<whatever>, then look at it.  */
 415 extern struct block *innermost_block;
 416
 417 /* From eval.c */
 418
 419 /* Values of NOSIDE argument to eval_subexp.  */
 420
 421 enum noside
 422   {
 423     EVAL_NORMAL,
 424     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 425     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 426                                    call any functions.  The value
 427                                    returned will have the correct
 428                                    type, and will have an
 429                                    approximately correct lvalue
 430                                    type (inaccuracy: anything that is
 431                                    listed as being in a register in
 432                                    the function in which it was
 433                                    declared will be lval_register).  */
 434   };
 435
 436 extern struct value *evaluate_subexp_standard
 437   (struct type *, struct expression *, int *, enum noside);
 438
 439 /* From expprint.c */
 440
 441 extern void print_expression (struct expression *, struct ui_file *);
 442
 443 extern char *op_string (enum exp_opcode);
 444
 445 extern void dump_raw_expression (struct expression *, struct ui_file *, char *);
 446 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 447
 448 #endif /* !defined (EXPRESSION_H) */