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    2010 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     /* The C++ dynamic_cast operator.  */
 237     UNOP_DYNAMIC_CAST,
 238
 239     /* The C++ reinterpret_cast operator.  */
 240     UNOP_REINTERPRET_CAST,
 241
 242     /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
 243        With another UNOP_MEMVAL at the end, this makes three exp_elements.
 244        It casts the contents of the word addressed by the value of the
 245        following subexpression.  */
 246     UNOP_MEMVAL,
 247
 248     /* UNOP_MEMVAL_TLS is followed by a `struct objfile' pointer in the next
 249        exp_element and a type pointer in the following exp_element.
 250        With another UNOP_MEMVAL_TLS at the end, this makes four exp_elements.
 251        It casts the contents of the word offsetted by the value of the
 252        following subexpression from the TLS specified by `struct objfile'.  */
 253     UNOP_MEMVAL_TLS,
 254
 255     /* UNOP_... operate on one value from a following subexpression
 256        and replace it with a result.  They take no immediate arguments.  */
 257
 258     UNOP_NEG,                   /* Unary - */
 259     UNOP_LOGICAL_NOT,           /* Unary ! */
 260     UNOP_COMPLEMENT,            /* Unary ~ */
 261     UNOP_IND,                   /* Unary * */
 262     UNOP_ADDR,                  /* Unary & */
 263     UNOP_PREINCREMENT,          /* ++ before an expression */
 264     UNOP_POSTINCREMENT,         /* ++ after an expression */
 265     UNOP_PREDECREMENT,          /* -- before an expression */
 266     UNOP_POSTDECREMENT,         /* -- after an expression */
 267     UNOP_SIZEOF,                /* Unary sizeof (followed by expression) */
 268
 269     UNOP_PLUS,                  /* Unary plus */
 270
 271     UNOP_CAP,                   /* Modula-2 standard (unary) procedures */
 272     UNOP_CHR,
 273     UNOP_ORD,
 274     UNOP_ABS,
 275     UNOP_FLOAT,
 276     UNOP_HIGH,
 277     UNOP_MAX,
 278     UNOP_MIN,
 279     UNOP_ODD,
 280     UNOP_TRUNC,
 281
 282     /* (The deleted) Chill builtin functions.  */
 283     UNOP_LOWER, UNOP_UPPER, UNOP_LENGTH, UNOP_CARD, UNOP_CHMAX, UNOP_CHMIN,
 284
 285     OP_BOOL,                    /* Modula-2 builtin BOOLEAN type */
 286     OP_M2_STRING,               /* Modula-2 string constants */
 287
 288     /* STRUCTOP_... operate on a value from a following subexpression
 289        by extracting a structure component specified by a string
 290        that appears in the following exp_elements (as many as needed).
 291        STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
 292        They differ only in the error message given in case the value is
 293        not suitable or the structure component specified is not found.
 294
 295        The length of the string follows the opcode, followed by
 296        BYTES_TO_EXP_ELEM(length) elements containing the data of the
 297        string, followed by the length again and the opcode again.  */
 298
 299     STRUCTOP_STRUCT,
 300     STRUCTOP_PTR,
 301
 302     /* C++: OP_THIS is just a placeholder for the class instance variable.
 303        It just comes in a tight (OP_THIS, OP_THIS) pair.  */
 304     OP_THIS,
 305
 306     /* Objective-C: OP_OBJC_SELF is just a placeholder for the class instance
 307        variable.  It just comes in a tight (OP_OBJC_SELF, OP_OBJC_SELF) pair.  */
 308     OP_OBJC_SELF,
 309
 310     /* Objective C: "@selector" pseudo-operator */
 311     OP_OBJC_SELECTOR,
 312
 313     /* OP_SCOPE surrounds a type name and a field name.  The type
 314        name is encoded as one element, but the field name stays as
 315        a string, which, of course, is variable length.  */
 316     OP_SCOPE,
 317
 318     /* Used to represent named structure field values in brace
 319        initializers (or tuples as they are called in (the deleted)
 320        Chill).
 321
 322        The gcc C syntax is NAME:VALUE or .NAME=VALUE, the (the
 323        deleted) Chill syntax is .NAME:VALUE.  Multiple labels (as in
 324        the (the deleted) Chill syntax .NAME1,.NAME2:VALUE) is
 325        represented as if it were .NAME1:(.NAME2:VALUE) (though that is
 326        not valid (the deleted) Chill syntax).
 327
 328        The NAME is represented as for STRUCTOP_STRUCT;  VALUE follows. */
 329     OP_LABELED,
 330
 331     /* OP_TYPE is for parsing types, and used with the "ptype" command
 332        so we can look up types that are qualified by scope, either with
 333        the GDB "::" operator, or the Modula-2 '.' operator. */
 334     OP_TYPE,
 335
 336     /* An un-looked-up identifier. */
 337     OP_NAME,
 338
 339     /* An Objective C Foundation Class NSString constant */
 340     OP_OBJC_NSSTRING,
 341
 342     /* A F90 array range operator (for "exp:exp", "exp:", ":exp" and ":").  */
 343     OP_F90_RANGE,
 344
 345     /* OP_DECFLOAT is followed by a type pointer in the next exp_element
 346        and a dec long constant value in the following exp_element.
 347        Then comes another OP_DECFLOAT.  */
 348     OP_DECFLOAT,
 349
 350     /* OP_ADL_FUNC specifies that the function is to be looked up in an
 351        Argument Dependent manner (Koenig lookup).  */
 352     OP_ADL_FUNC,
 353
 354      /* First extension operator.  Individual language modules define
 355         extra operators in *.inc include files below always starting with
 356         numbering at OP_EXTENDED0:
 357              BINOP_MOGRIFY = OP_EXTENDED0,
 358              BINOP_FROB,
 359              ...  */
 360     OP_EXTENDED0,
 361
 362     /* Last possible extension operator.  Defined to provide an
 363        explicit and finite number of extended operators. */
 364     OP_EXTENDED_LAST = 0xff,
 365     /* NOTE: Eventually, we expect to convert to an object-oriented
 366        formulation for expression operators that does away with the
 367        need for these extension operators, and indeed for this
 368        entire enumeration type.  Therefore, consider the OP_EXTENDED
 369        definitions to be a temporary measure. */
 370
 371     /* Each language specific set of operators starts at OP_EXTENDED0.  */
 372 #include "ada-operator.inc"
 373
 374     /* Existing only to swallow the last comma (',') from last .inc file.  */
 375     OP_UNUSED_LAST
 376   };
 377
 378 union exp_element
 379   {
 380     enum exp_opcode opcode;
 381     struct symbol *symbol;
 382     LONGEST longconst;
 383     DOUBLEST doubleconst;
 384     gdb_byte decfloatconst[16];
 385     /* Really sizeof (union exp_element) characters (or less for the last
 386        element of a string).  */
 387     char string;
 388     struct type *type;
 389     struct internalvar *internalvar;
 390     struct block *block;
 391     struct objfile *objfile;
 392   };
 393
 394 struct expression
 395   {
 396     const struct language_defn *language_defn;  /* language it was entered in */
 397     struct gdbarch *gdbarch;  /* architecture it was parsed in */
 398     int nelts;
 399     union exp_element elts[1];
 400   };
 401
 402 /* Macros for converting between number of expression elements and bytes
 403    to store that many expression elements. */
 404
 405 #define EXP_ELEM_TO_BYTES(elements) \
 406     ((elements) * sizeof (union exp_element))
 407 #define BYTES_TO_EXP_ELEM(bytes) \
 408     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 409
 410 /* From parse.c */
 411
 412 extern struct expression *parse_expression (char *);
 413
 414 extern struct type *parse_field_expression (char *, char **);
 415
 416 extern struct expression *parse_exp_1 (char **, struct block *, int);
 417
 418 /* For use by parsers; set if we want to parse an expression and
 419    attempt to complete a field name.  */
 420 extern int in_parse_field;
 421
 422 /* The innermost context required by the stack and register variables
 423    we've encountered so far.  To use this, set it to NULL, then call
 424    parse_<whatever>, then look at it.  */
 425 extern struct block *innermost_block;
 426
 427 /* From eval.c */
 428
 429 /* Values of NOSIDE argument to eval_subexp.  */
 430
 431 enum noside
 432   {
 433     EVAL_NORMAL,
 434     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 435     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 436                                    call any functions.  The value
 437                                    returned will have the correct
 438                                    type, and will have an
 439                                    approximately correct lvalue
 440                                    type (inaccuracy: anything that is
 441                                    listed as being in a register in
 442                                    the function in which it was
 443                                    declared will be lval_register).  */
 444   };
 445
 446 extern struct value *evaluate_subexp_standard
 447   (struct type *, struct expression *, int *, enum noside);
 448
 449 /* From expprint.c */
 450
 451 extern void print_expression (struct expression *, struct ui_file *);
 452
 453 extern char *op_string (enum exp_opcode);
 454
 455 extern void dump_raw_expression (struct expression *, struct ui_file *, char *);
 456 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 457
 458 #endif /* !defined (EXPRESSION_H) */