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, 2011 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
 112     /* Concatenate two operands, such as character strings or bitstrings.
 113        If the first operand is a integer expression, then it means concatenate
 114        the second operand with itself that many times.  */
 115     BINOP_CONCAT,
 116
 117     /* For (the deleted) Chill and Pascal.  */
 118     BINOP_IN,                   /* Returns 1 iff ARG1 IN ARG2.  */
 119
 120     /* This is the "colon operator" used various places in (the
 121        deleted) Chill.  */
 122     BINOP_RANGE,
 123
 124     /* This must be the highest BINOP_ value, for expprint.c.  */
 125     BINOP_END,
 126
 127     /* Operates on three values computed by following subexpressions.  */
 128     TERNOP_COND,                /* ?: */
 129
 130     /* A sub-string/sub-array.  (the deleted) Chill syntax:
 131        OP1(OP2:OP3).  Return elements OP2 through OP3 of OP1.  */
 132     TERNOP_SLICE,
 133
 134     /* A sub-string/sub-array.  (The deleted) Chill syntax: OP1(OP2 UP
 135        OP3).  Return OP3 elements of OP1, starting with element
 136        OP2.  */
 137     TERNOP_SLICE_COUNT,
 138
 139     /* Multidimensional subscript operator, such as Modula-2 x[a,b,...].
 140        The dimensionality is encoded in the operator, like the number of
 141        function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>.
 142        The value of the first following subexpression is subscripted
 143        by each of the next following subexpressions, one per dimension.  */
 144     MULTI_SUBSCRIPT,
 145
 146     /* The OP_... series take immediate following arguments.
 147        After the arguments come another OP_... (the same one)
 148        so that the grouping can be recognized from the end.  */
 149
 150     /* OP_LONG is followed by a type pointer in the next exp_element
 151        and the long constant value in the following exp_element.
 152        Then comes another OP_LONG.
 153        Thus, the operation occupies four exp_elements.  */
 154     OP_LONG,
 155
 156     /* OP_DOUBLE is similar but takes a DOUBLEST constant instead of a
 157        long.  */
 158     OP_DOUBLE,
 159
 160     /* OP_VAR_VALUE takes one struct block * in the following element,
 161        and one struct symbol * in the following exp_element, followed
 162        by another OP_VAR_VALUE, making four exp_elements.  If the
 163        block is non-NULL, evaluate the symbol relative to the
 164        innermost frame executing in that block; if the block is NULL
 165        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
 179        exp_element.  With another OP_INTERNALVAR at the end, this
 180        makes three exp_elements.  */
 181     OP_INTERNALVAR,
 182
 183     /* OP_FUNCALL is followed by an integer in the next exp_element.
 184        The integer is the number of args to the function call.
 185        That many plus one values from following subexpressions
 186        are used, the first one being the function.
 187        The integer is followed by a repeat of OP_FUNCALL,
 188        making three exp_elements.  */
 189     OP_FUNCALL,
 190
 191     /* OP_OBJC_MSGCALL is followed by a string in the next exp_element
 192        and then an integer.  The string is the selector string.  The
 193        integer is the number of arguments to the message call.  That
 194        many plus one values are used, the first one being the object
 195        pointer.  This is an Objective C message.  */
 196     OP_OBJC_MSGCALL,
 197
 198     /* This is EXACTLY like OP_FUNCALL but is semantically different.
 199        In F77, array subscript expressions, substring expressions and
 200        function calls are all exactly the same syntactically.  They
 201        may only be disambiguated at runtime.  Thus this operator,
 202        which indicates that we have found something of the form
 203        <name> ( <stuff> ).  */
 204     OP_F77_UNDETERMINED_ARGLIST,
 205
 206     /* OP_COMPLEX takes a type in the following element, followed by another
 207        OP_COMPLEX, making three exp_elements.  It is followed by two double
 208        args, and converts them into a complex number of the given type.  */
 209     OP_COMPLEX,
 210
 211     /* OP_STRING represents a string constant.
 212        Its format is the same as that of a STRUCTOP, but the string
 213        data is just made into a string constant when the operation
 214        is executed.  */
 215     OP_STRING,
 216
 217     /* OP_BITSTRING represents a packed bitstring constant.
 218        Its format is the same as that of a STRUCTOP, but the bitstring
 219        data is just made into a bitstring constant when the operation
 220        is executed.  */
 221     OP_BITSTRING,
 222
 223     /* OP_ARRAY creates an array constant out of the following subexpressions.
 224        It is followed by two exp_elements, the first containing an integer
 225        that is the lower bound of the array and the second containing another
 226        integer that is the upper bound of the array.  The second integer is
 227        followed by a repeat of OP_ARRAY, making four exp_elements total.
 228        The bounds are used to compute the number of following subexpressions
 229        to consume, as well as setting the bounds in the created array constant.
 230        The type of the elements is taken from the type of the first subexp,
 231        and they must all match.  */
 232     OP_ARRAY,
 233
 234     /* UNOP_CAST is followed by a type pointer in the next exp_element.
 235        With another UNOP_CAST at the end, this makes three exp_elements.
 236        It casts the value of the following subexpression.  */
 237     UNOP_CAST,
 238
 239     /* The C++ dynamic_cast operator.  */
 240     UNOP_DYNAMIC_CAST,
 241
 242     /* The C++ reinterpret_cast operator.  */
 243     UNOP_REINTERPRET_CAST,
 244
 245     /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
 246        With another UNOP_MEMVAL at the end, this makes three exp_elements.
 247        It casts the contents of the word addressed by the value of the
 248        following subexpression.  */
 249     UNOP_MEMVAL,
 250
 251     /* UNOP_MEMVAL_TLS is followed by a `struct objfile' pointer in the next
 252        exp_element and a type pointer in the following exp_element.
 253        With another UNOP_MEMVAL_TLS at the end, this makes four exp_elements.
 254        It casts the contents of the word offsetted by the value of the
 255        following subexpression from the TLS specified by `struct objfile'.  */
 256     UNOP_MEMVAL_TLS,
 257
 258     /* UNOP_... operate on one value from a following subexpression
 259        and replace it with a result.  They take no immediate arguments.  */
 260
 261     UNOP_NEG,                   /* Unary - */
 262     UNOP_LOGICAL_NOT,           /* Unary ! */
 263     UNOP_COMPLEMENT,            /* Unary ~ */
 264     UNOP_IND,                   /* Unary * */
 265     UNOP_ADDR,                  /* Unary & */
 266     UNOP_PREINCREMENT,          /* ++ before an expression */
 267     UNOP_POSTINCREMENT,         /* ++ after an expression */
 268     UNOP_PREDECREMENT,          /* -- before an expression */
 269     UNOP_POSTDECREMENT,         /* -- after an expression */
 270     UNOP_SIZEOF,                /* Unary sizeof (followed by expression) */
 271
 272     UNOP_PLUS,                  /* Unary plus */
 273
 274     UNOP_CAP,                   /* Modula-2 standard (unary) procedures */
 275     UNOP_CHR,
 276     UNOP_ORD,
 277     UNOP_ABS,
 278     UNOP_FLOAT,
 279     UNOP_HIGH,
 280     UNOP_MAX,
 281     UNOP_MIN,
 282     UNOP_ODD,
 283     UNOP_TRUNC,
 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
 307        instance variable.  It just comes in a tight (OP_OBJC_SELF,
 308        OP_OBJC_SELF) pair.  */
 309     OP_OBJC_SELF,
 310
 311     /* Objective C: "@selector" pseudo-operator.  */
 312     OP_OBJC_SELECTOR,
 313
 314     /* OP_SCOPE surrounds a type name and a field name.  The type
 315        name is encoded as one element, but the field name stays as
 316        a string, which, of course, is variable length.  */
 317     OP_SCOPE,
 318
 319     /* Used to represent named structure field values in brace
 320        initializers (or tuples as they are called in (the deleted)
 321        Chill).
 322
 323        The gcc C syntax is NAME:VALUE or .NAME=VALUE, the (the
 324        deleted) Chill syntax is .NAME:VALUE.  Multiple labels (as in
 325        the (the deleted) Chill syntax .NAME1,.NAME2:VALUE) is
 326        represented as if it were .NAME1:(.NAME2:VALUE) (though that is
 327        not valid (the deleted) Chill syntax).
 328
 329        The NAME is represented as for STRUCTOP_STRUCT;  VALUE follows.  */
 330     OP_LABELED,
 331
 332     /* OP_TYPE is for parsing types, and used with the "ptype" command
 333        so we can look up types that are qualified by scope, either with
 334        the GDB "::" operator, or the Modula-2 '.' operator.  */
 335     OP_TYPE,
 336
 337     /* An un-looked-up identifier.  */
 338     OP_NAME,
 339
 340     /* An Objective C Foundation Class NSString constant.  */
 341     OP_OBJC_NSSTRING,
 342
 343     /* A F90 array range operator (for "exp:exp", "exp:", ":exp" and ":").  */
 344     OP_F90_RANGE,
 345
 346     /* OP_DECFLOAT is followed by a type pointer in the next exp_element
 347        and a dec long constant value in the following exp_element.
 348        Then comes another OP_DECFLOAT.  */
 349     OP_DECFLOAT,
 350
 351     /* OP_ADL_FUNC specifies that the function is to be looked up in an
 352        Argument Dependent manner (Koenig lookup).  */
 353     OP_ADL_FUNC,
 354
 355      /* First extension operator.  Individual language modules define
 356         extra operators in *.inc include files below always starting with
 357         numbering at OP_EXTENDED0:
 358              BINOP_MOGRIFY = OP_EXTENDED0,
 359              BINOP_FROB,
 360              ...  */
 361     OP_EXTENDED0,
 362
 363     /* Last possible extension operator.  Defined to provide an
 364        explicit and finite number of extended operators.  */
 365     OP_EXTENDED_LAST = 0xff,
 366     /* NOTE: Eventually, we expect to convert to an object-oriented
 367        formulation for expression operators that does away with the
 368        need for these extension operators, and indeed for this
 369        entire enumeration type.  Therefore, consider the OP_EXTENDED
 370        definitions to be a temporary measure.  */
 371
 372     /* Each language specific set of operators starts at OP_EXTENDED0.  */
 373 #include "ada-operator.inc"
 374
 375     /* Existing only to swallow the last comma (',') from last .inc file.  */
 376     OP_UNUSED_LAST
 377   };
 378
 379 union exp_element
 380   {
 381     enum exp_opcode opcode;
 382     struct symbol *symbol;
 383     LONGEST longconst;
 384     DOUBLEST doubleconst;
 385     gdb_byte decfloatconst[16];
 386     /* Really sizeof (union exp_element) characters (or less for the last
 387        element of a string).  */
 388     char string;
 389     struct type *type;
 390     struct internalvar *internalvar;
 391     struct block *block;
 392     struct objfile *objfile;
 393   };
 394
 395 struct expression
 396   {
 397     const struct language_defn *language_defn;  /* language it was
 398                                                    entered in.  */
 399     struct gdbarch *gdbarch;  /* architecture it was parsed in.  */
 400     int nelts;
 401     union exp_element elts[1];
 402   };
 403
 404 /* Macros for converting between number of expression elements and bytes
 405    to store that many expression elements.  */
 406
 407 #define EXP_ELEM_TO_BYTES(elements) \
 408     ((elements) * sizeof (union exp_element))
 409 #define BYTES_TO_EXP_ELEM(bytes) \
 410     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 411
 412 /* From parse.c */
 413
 414 extern struct expression *parse_expression (char *);
 415
 416 extern struct type *parse_field_expression (char *, char **);
 417
 418 extern struct expression *parse_exp_1 (char **, struct block *, int);
 419
 420 /* For use by parsers; set if we want to parse an expression and
 421    attempt to complete a field name.  */
 422 extern int in_parse_field;
 423
 424 /* The innermost context required by the stack and register variables
 425    we've encountered so far.  To use this, set it to NULL, then call
 426    parse_<whatever>, then look at it.  */
 427 extern struct block *innermost_block;
 428
 429 /* From eval.c */
 430
 431 /* Values of NOSIDE argument to eval_subexp.  */
 432
 433 enum noside
 434   {
 435     EVAL_NORMAL,
 436     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 437     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 438                                    call any functions.  The value
 439                                    returned will have the correct
 440                                    type, and will have an
 441                                    approximately correct lvalue
 442                                    type (inaccuracy: anything that is
 443                                    listed as being in a register in
 444                                    the function in which it was
 445                                    declared will be lval_register).  */
 446   };
 447
 448 extern struct value *evaluate_subexp_standard
 449   (struct type *, struct expression *, int *, enum noside);
 450
 451 /* From expprint.c */
 452
 453 extern void print_expression (struct expression *, struct ui_file *);
 454
 455 extern char *op_string (enum exp_opcode);
 456
 457 extern void dump_raw_expression (struct expression *,
 458                                  struct ui_file *, char *);
 459 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 460
 461 #endif /* !defined (EXPRESSION_H) */