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
 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 long.  */
 157     OP_DOUBLE,
 158
 159     /* OP_VAR_VALUE takes one struct block * in the following element,
 160        and one struct symbol * in the following exp_element, followed by
 161        another OP_VAR_VALUE, making four exp_elements.  If the block is
 162        non-NULL, evaluate the symbol relative to the innermost frame
 163        executing in that block; if the block is NULL use the selected frame.  */
 164     OP_VAR_VALUE,
 165
 166     /* OP_LAST is followed by an integer in the next exp_element.
 167        The integer is zero for the last value printed,
 168        or it is the absolute number of a history element.
 169        With another OP_LAST at the end, this makes three exp_elements.  */
 170     OP_LAST,
 171
 172     /* OP_REGISTER is followed by a string in the next exp_element.
 173        This is the name of a register to fetch.  */
 174     OP_REGISTER,
 175
 176     /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
 177        With another OP_INTERNALVAR at the end, this makes three exp_elements.  */
 178     OP_INTERNALVAR,
 179
 180     /* OP_FUNCALL is followed by an integer in the next exp_element.
 181        The integer is the number of args to the function call.
 182        That many plus one values from following subexpressions
 183        are used, the first one being the function.
 184        The integer is followed by a repeat of OP_FUNCALL,
 185        making three exp_elements.  */
 186     OP_FUNCALL,
 187
 188     /* OP_OBJC_MSGCALL is followed by a string in the next exp_element and then an
 189        integer.  The string is the selector string.  The integer is the number
 190        of arguments to the message call.  That many plus one values are used,
 191        the first one being the object pointer.  This is an Objective C message */
 192     OP_OBJC_MSGCALL,
 193
 194     /* This is EXACTLY like OP_FUNCALL but is semantically different.
 195        In F77, array subscript expressions, substring expressions
 196        and function calls are  all exactly the same syntactically. They may
 197        only be disambiguated at runtime.  Thus this operator, which
 198        indicates that we have found something of the form <name> ( <stuff> ) */
 199     OP_F77_UNDETERMINED_ARGLIST,
 200
 201     /* OP_COMPLEX takes a type in the following element, followed by another
 202        OP_COMPLEX, making three exp_elements.  It is followed by two double
 203        args, and converts them into a complex number of the given type. */
 204     OP_COMPLEX,
 205
 206     /* OP_STRING represents a string constant.
 207        Its format is the same as that of a STRUCTOP, but the string
 208        data is just made into a string constant when the operation
 209        is executed.  */
 210     OP_STRING,
 211
 212     /* OP_BITSTRING represents a packed bitstring constant.
 213        Its format is the same as that of a STRUCTOP, but the bitstring
 214        data is just made into a bitstring constant when the operation
 215        is executed.  */
 216     OP_BITSTRING,
 217
 218     /* OP_ARRAY creates an array constant out of the following subexpressions.
 219        It is followed by two exp_elements, the first containing an integer
 220        that is the lower bound of the array and the second containing another
 221        integer that is the upper bound of the array.  The second integer is
 222        followed by a repeat of OP_ARRAY, making four exp_elements total.
 223        The bounds are used to compute the number of following subexpressions
 224        to consume, as well as setting the bounds in the created array constant.
 225        The type of the elements is taken from the type of the first subexp,
 226        and they must all match. */
 227     OP_ARRAY,
 228
 229     /* UNOP_CAST is followed by a type pointer in the next exp_element.
 230        With another UNOP_CAST at the end, this makes three exp_elements.
 231        It casts the value of the following subexpression.  */
 232     UNOP_CAST,
 233
 234     /* The C++ dynamic_cast operator.  */
 235     UNOP_DYNAMIC_CAST,
 236
 237     /* The C++ reinterpret_cast operator.  */
 238     UNOP_REINTERPRET_CAST,
 239
 240     /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
 241        With another UNOP_MEMVAL at the end, this makes three exp_elements.
 242        It casts the contents of the word addressed by the value of the
 243        following subexpression.  */
 244     UNOP_MEMVAL,
 245
 246     /* UNOP_MEMVAL_TLS is followed by a `struct objfile' pointer in the next
 247        exp_element and a type pointer in the following exp_element.
 248        With another UNOP_MEMVAL_TLS at the end, this makes four exp_elements.
 249        It casts the contents of the word offsetted by the value of the
 250        following subexpression from the TLS specified by `struct objfile'.  */
 251     UNOP_MEMVAL_TLS,
 252
 253     /* UNOP_... operate on one value from a following subexpression
 254        and replace it with a result.  They take no immediate arguments.  */
 255
 256     UNOP_NEG,                   /* Unary - */
 257     UNOP_LOGICAL_NOT,           /* Unary ! */
 258     UNOP_COMPLEMENT,            /* Unary ~ */
 259     UNOP_IND,                   /* Unary * */
 260     UNOP_ADDR,                  /* Unary & */
 261     UNOP_PREINCREMENT,          /* ++ before an expression */
 262     UNOP_POSTINCREMENT,         /* ++ after an expression */
 263     UNOP_PREDECREMENT,          /* -- before an expression */
 264     UNOP_POSTDECREMENT,         /* -- after an expression */
 265     UNOP_SIZEOF,                /* Unary sizeof (followed by expression) */
 266
 267     UNOP_PLUS,                  /* Unary plus */
 268
 269     UNOP_CAP,                   /* Modula-2 standard (unary) procedures */
 270     UNOP_CHR,
 271     UNOP_ORD,
 272     UNOP_ABS,
 273     UNOP_FLOAT,
 274     UNOP_HIGH,
 275     UNOP_MAX,
 276     UNOP_MIN,
 277     UNOP_ODD,
 278     UNOP_TRUNC,
 279
 280     OP_BOOL,                    /* Modula-2 builtin BOOLEAN type */
 281     OP_M2_STRING,               /* Modula-2 string constants */
 282
 283     /* STRUCTOP_... operate on a value from a following subexpression
 284        by extracting a structure component specified by a string
 285        that appears in the following exp_elements (as many as needed).
 286        STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
 287        They differ only in the error message given in case the value is
 288        not suitable or the structure component specified is not found.
 289
 290        The length of the string follows the opcode, followed by
 291        BYTES_TO_EXP_ELEM(length) elements containing the data of the
 292        string, followed by the length again and the opcode again.  */
 293
 294     STRUCTOP_STRUCT,
 295     STRUCTOP_PTR,
 296
 297     /* C++: OP_THIS is just a placeholder for the class instance variable.
 298        It just comes in a tight (OP_THIS, OP_THIS) pair.  */
 299     OP_THIS,
 300
 301     /* Objective-C: OP_OBJC_SELF is just a placeholder for the class instance
 302        variable.  It just comes in a tight (OP_OBJC_SELF, OP_OBJC_SELF) pair.  */
 303     OP_OBJC_SELF,
 304
 305     /* Objective C: "@selector" pseudo-operator */
 306     OP_OBJC_SELECTOR,
 307
 308     /* OP_SCOPE surrounds a type name and a field name.  The type
 309        name is encoded as one element, but the field name stays as
 310        a string, which, of course, is variable length.  */
 311     OP_SCOPE,
 312
 313     /* Used to represent named structure field values in brace
 314        initializers (or tuples as they are called in (the deleted)
 315        Chill).
 316
 317        The gcc C syntax is NAME:VALUE or .NAME=VALUE, the (the
 318        deleted) Chill syntax is .NAME:VALUE.  Multiple labels (as in
 319        the (the deleted) Chill syntax .NAME1,.NAME2:VALUE) is
 320        represented as if it were .NAME1:(.NAME2:VALUE) (though that is
 321        not valid (the deleted) Chill syntax).
 322
 323        The NAME is represented as for STRUCTOP_STRUCT;  VALUE follows. */
 324     OP_LABELED,
 325
 326     /* OP_TYPE is for parsing types, and used with the "ptype" command
 327        so we can look up types that are qualified by scope, either with
 328        the GDB "::" operator, or the Modula-2 '.' operator. */
 329     OP_TYPE,
 330
 331     /* An un-looked-up identifier. */
 332     OP_NAME,
 333
 334     /* An Objective C Foundation Class NSString constant */
 335     OP_OBJC_NSSTRING,
 336
 337     /* A F90 array range operator (for "exp:exp", "exp:", ":exp" and ":").  */
 338     OP_F90_RANGE,
 339
 340     /* OP_DECFLOAT is followed by a type pointer in the next exp_element
 341        and a dec long constant value in the following exp_element.
 342        Then comes another OP_DECFLOAT.  */
 343     OP_DECFLOAT,
 344
 345     /* OP_ADL_FUNC specifies that the function is to be looked up in an
 346        Argument Dependent manner (Koenig lookup).  */
 347     OP_ADL_FUNC,
 348
 349      /* First extension operator.  Individual language modules define
 350         extra operators in *.inc include files below always starting with
 351         numbering at OP_EXTENDED0:
 352              BINOP_MOGRIFY = OP_EXTENDED0,
 353              BINOP_FROB,
 354              ...  */
 355     OP_EXTENDED0,
 356
 357     /* Last possible extension operator.  Defined to provide an
 358        explicit and finite number of extended operators. */
 359     OP_EXTENDED_LAST = 0xff,
 360     /* NOTE: Eventually, we expect to convert to an object-oriented
 361        formulation for expression operators that does away with the
 362        need for these extension operators, and indeed for this
 363        entire enumeration type.  Therefore, consider the OP_EXTENDED
 364        definitions to be a temporary measure. */
 365
 366     /* Each language specific set of operators starts at OP_EXTENDED0.  */
 367 #include "ada-operator.inc"
 368
 369     /* Existing only to swallow the last comma (',') from last .inc file.  */
 370     OP_UNUSED_LAST
 371   };
 372
 373 union exp_element
 374   {
 375     enum exp_opcode opcode;
 376     struct symbol *symbol;
 377     LONGEST longconst;
 378     DOUBLEST doubleconst;
 379     gdb_byte decfloatconst[16];
 380     /* Really sizeof (union exp_element) characters (or less for the last
 381        element of a string).  */
 382     char string;
 383     struct type *type;
 384     struct internalvar *internalvar;
 385     struct block *block;
 386     struct objfile *objfile;
 387   };
 388
 389 struct expression
 390   {
 391     const struct language_defn *language_defn;  /* language it was entered in */
 392     struct gdbarch *gdbarch;  /* architecture it was parsed in */
 393     int nelts;
 394     union exp_element elts[1];
 395   };
 396
 397 /* Macros for converting between number of expression elements and bytes
 398    to store that many expression elements. */
 399
 400 #define EXP_ELEM_TO_BYTES(elements) \
 401     ((elements) * sizeof (union exp_element))
 402 #define BYTES_TO_EXP_ELEM(bytes) \
 403     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 404
 405 /* From parse.c */
 406
 407 extern struct expression *parse_expression (char *);
 408
 409 extern struct type *parse_field_expression (char *, char **);
 410
 411 extern struct expression *parse_exp_1 (char **, struct block *, int);
 412
 413 /* For use by parsers; set if we want to parse an expression and
 414    attempt to complete a field name.  */
 415 extern int in_parse_field;
 416
 417 /* The innermost context required by the stack and register variables
 418    we've encountered so far.  To use this, set it to NULL, then call
 419    parse_<whatever>, then look at it.  */
 420 extern struct block *innermost_block;
 421
 422 /* From eval.c */
 423
 424 /* Values of NOSIDE argument to eval_subexp.  */
 425
 426 enum noside
 427   {
 428     EVAL_NORMAL,
 429     EVAL_SKIP,                  /* Only effect is to increment pos.  */
 430     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 431                                    call any functions.  The value
 432                                    returned will have the correct
 433                                    type, and will have an
 434                                    approximately correct lvalue
 435                                    type (inaccuracy: anything that is
 436                                    listed as being in a register in
 437                                    the function in which it was
 438                                    declared will be lval_register).  */
 439   };
 440
 441 extern struct value *evaluate_subexp_standard
 442   (struct type *, struct expression *, int *, enum noside);
 443
 444 /* From expprint.c */
 445
 446 extern void print_expression (struct expression *, struct ui_file *);
 447
 448 extern char *op_string (enum exp_opcode);
 449
 450 extern void dump_raw_expression (struct expression *, struct ui_file *, char *);
 451 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 452
 453 #endif /* !defined (EXPRESSION_H) */