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 /* end of C++. */ 92 93 /* For Modula-2 integer division DIV */ 94 BINOP_INTDIV, 95 96 BINOP_ASSIGN_MODIFY, /* +=, -=, *=, and so on. 97 The following exp_element is another opcode, 98 a BINOP_, saying how to modify. 99 Then comes another BINOP_ASSIGN_MODIFY, 100 making three exp_elements in total. */ 101 102 /* Modula-2 standard (binary) procedures */ 103 BINOP_VAL, 104 BINOP_INCL, 105 BINOP_EXCL, 106 107 /* Concatenate two operands, such as character strings or bitstrings. 108 If the first operand is a integer expression, then it means concatenate 109 the second operand with itself that many times. */ 110 BINOP_CONCAT, 111 112 /* For (the deleted) Chill and Pascal. */ 113 BINOP_IN, /* Returns 1 iff ARG1 IN ARG2. */ 114 115 /* This is the "colon operator" used various places in (the 116 deleted) Chill. */ 117 BINOP_RANGE, 118 119 /* This must be the highest BINOP_ value, for expprint.c. */ 120 BINOP_END, 121 122 /* Operates on three values computed by following subexpressions. */ 123 TERNOP_COND, /* ?: */ 124 125 /* A sub-string/sub-array. (the deleted) Chill syntax: 126 OP1(OP2:OP3). Return elements OP2 through OP3 of OP1. */ 127 TERNOP_SLICE, 128 129 /* A sub-string/sub-array. (The deleted) Chill syntax: OP1(OP2 UP 130 OP3). Return OP3 elements of OP1, starting with element 131 OP2. */ 132 TERNOP_SLICE_COUNT, 133 134 /* Multidimensional subscript operator, such as Modula-2 x[a,b,...]. 135 The dimensionality is encoded in the operator, like the number of 136 function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>. 137 The value of the first following subexpression is subscripted 138 by each of the next following subexpressions, one per dimension. */ 139 MULTI_SUBSCRIPT, 140 141 /* The OP_... series take immediate following arguments. 142 After the arguments come another OP_... (the same one) 143 so that the grouping can be recognized from the end. */ 144 145 /* OP_LONG is followed by a type pointer in the next exp_element 146 and the long constant value in the following exp_element. 147 Then comes another OP_LONG. 148 Thus, the operation occupies four exp_elements. */ 149 OP_LONG, 150 151 /* OP_DOUBLE is similar but takes a DOUBLEST constant instead of a long. */ 152 OP_DOUBLE, 153 154 /* OP_VAR_VALUE takes one struct block * in the following element, 155 and one struct symbol * in the following exp_element, followed by 156 another OP_VAR_VALUE, making four exp_elements. If the block is 157 non-NULL, evaluate the symbol relative to the innermost frame 158 executing in that block; if the block is NULL use the selected frame. */ 159 OP_VAR_VALUE, 160 161 /* OP_LAST is followed by an integer in the next exp_element. 162 The integer is zero for the last value printed, 163 or it is the absolute number of a history element. 164 With another OP_LAST at the end, this makes three exp_elements. */ 165 OP_LAST, 166 167 /* OP_REGISTER is followed by a string in the next exp_element. 168 This is the name of a register to fetch. */ 169 OP_REGISTER, 170 171 /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element. 172 With another OP_INTERNALVAR at the end, this makes three exp_elements. */ 173 OP_INTERNALVAR, 174 175 /* OP_FUNCALL is followed by an integer in the next exp_element. 176 The integer is the number of args to the function call. 177 That many plus one values from following subexpressions 178 are used, the first one being the function. 179 The integer is followed by a repeat of OP_FUNCALL, 180 making three exp_elements. */ 181 OP_FUNCALL, 182 183 /* OP_OBJC_MSGCALL is followed by a string in the next exp_element and then an 184 integer. The string is the selector string. The integer is the number 185 of arguments to the message call. That many plus one values are used, 186 the first one being the object pointer. This is an Objective C message */ 187 OP_OBJC_MSGCALL, 188 189 /* This is EXACTLY like OP_FUNCALL but is semantically different. 190 In F77, array subscript expressions, substring expressions 191 and function calls are all exactly the same syntactically. They may 192 only be disambiguated at runtime. Thus this operator, which 193 indicates that we have found something of the form <name> ( <stuff> ) */ 194 OP_F77_UNDETERMINED_ARGLIST, 195 196 /* OP_COMPLEX takes a type in the following element, followed by another 197 OP_COMPLEX, making three exp_elements. It is followed by two double 198 args, and converts them into a complex number of the given type. */ 199 OP_COMPLEX, 200 201 /* OP_STRING represents a string constant. 202 Its format is the same as that of a STRUCTOP, but the string 203 data is just made into a string constant when the operation 204 is executed. */ 205 OP_STRING, 206 207 /* OP_BITSTRING represents a packed bitstring constant. 208 Its format is the same as that of a STRUCTOP, but the bitstring 209 data is just made into a bitstring constant when the operation 210 is executed. */ 211 OP_BITSTRING, 212 213 /* OP_ARRAY creates an array constant out of the following subexpressions. 214 It is followed by two exp_elements, the first containing an integer 215 that is the lower bound of the array and the second containing another 216 integer that is the upper bound of the array. The second integer is 217 followed by a repeat of OP_ARRAY, making four exp_elements total. 218 The bounds are used to compute the number of following subexpressions 219 to consume, as well as setting the bounds in the created array constant. 220 The type of the elements is taken from the type of the first subexp, 221 and they must all match. */ 222 OP_ARRAY, 223 224 /* UNOP_CAST is followed by a type pointer in the next exp_element. 225 With another UNOP_CAST at the end, this makes three exp_elements. 226 It casts the value of the following subexpression. */ 227 UNOP_CAST, 228 229 /* UNOP_MEMVAL is followed by a type pointer in the next exp_element 230 With another UNOP_MEMVAL at the end, this makes three exp_elements. 231 It casts the contents of the word addressed by the value of the 232 following subexpression. */ 233 UNOP_MEMVAL, 234 235 /* UNOP_MEMVAL_TLS is followed by a `struct objfile' pointer in the next 236 exp_element and a type pointer in the following exp_element. 237 With another UNOP_MEMVAL_TLS at the end, this makes four exp_elements. 238 It casts the contents of the word offsetted by the value of the 239 following subexpression from the TLS specified by `struct objfile'. */ 240 UNOP_MEMVAL_TLS, 241 242 /* UNOP_... operate on one value from a following subexpression 243 and replace it with a result. They take no immediate arguments. */ 244 245 UNOP_NEG, /* Unary - */ 246 UNOP_LOGICAL_NOT, /* Unary ! */ 247 UNOP_COMPLEMENT, /* Unary ~ */ 248 UNOP_IND, /* Unary * */ 249 UNOP_ADDR, /* Unary & */ 250 UNOP_PREINCREMENT, /* ++ before an expression */ 251 UNOP_POSTINCREMENT, /* ++ after an expression */ 252 UNOP_PREDECREMENT, /* -- before an expression */ 253 UNOP_POSTDECREMENT, /* -- after an expression */ 254 UNOP_SIZEOF, /* Unary sizeof (followed by expression) */ 255 256 UNOP_PLUS, /* Unary plus */ 257 258 UNOP_CAP, /* Modula-2 standard (unary) procedures */ 259 UNOP_CHR, 260 UNOP_ORD, 261 UNOP_ABS, 262 UNOP_FLOAT, 263 UNOP_HIGH, 264 UNOP_MAX, 265 UNOP_MIN, 266 UNOP_ODD, 267 UNOP_TRUNC, 268 269 /* (The deleted) Chill builtin functions. */ 270 UNOP_LOWER, UNOP_UPPER, UNOP_LENGTH, UNOP_CARD, UNOP_CHMAX, UNOP_CHMIN, 271 272 OP_BOOL, /* Modula-2 builtin BOOLEAN type */ 273 OP_M2_STRING, /* Modula-2 string constants */ 274 275 /* STRUCTOP_... operate on a value from a following subexpression 276 by extracting a structure component specified by a string 277 that appears in the following exp_elements (as many as needed). 278 STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->". 279 They differ only in the error message given in case the value is 280 not suitable or the structure component specified is not found. 281 282 The length of the string follows the opcode, followed by 283 BYTES_TO_EXP_ELEM(length) elements containing the data of the 284 string, followed by the length again and the opcode again. */ 285 286 STRUCTOP_STRUCT, 287 STRUCTOP_PTR, 288 289 /* C++: OP_THIS is just a placeholder for the class instance variable. 290 It just comes in a tight (OP_THIS, OP_THIS) pair. */ 291 OP_THIS, 292 293 /* Objective-C: OP_OBJC_SELF is just a placeholder for the class instance 294 variable. It just comes in a tight (OP_OBJC_SELF, OP_OBJC_SELF) pair. */ 295 OP_OBJC_SELF, 296 297 /* Objective C: "@selector" pseudo-operator */ 298 OP_OBJC_SELECTOR, 299 300 /* OP_SCOPE surrounds a type name and a field name. The type 301 name is encoded as one element, but the field name stays as 302 a string, which, of course, is variable length. */ 303 OP_SCOPE, 304 305 /* Used to represent named structure field values in brace 306 initializers (or tuples as they are called in (the deleted) 307 Chill). 308 309 The gcc C syntax is NAME:VALUE or .NAME=VALUE, the (the 310 deleted) Chill syntax is .NAME:VALUE. Multiple labels (as in 311 the (the deleted) Chill syntax .NAME1,.NAME2:VALUE) is 312 represented as if it were .NAME1:(.NAME2:VALUE) (though that is 313 not valid (the deleted) Chill syntax). 314 315 The NAME is represented as for STRUCTOP_STRUCT; VALUE follows. */ 316 OP_LABELED, 317 318 /* OP_TYPE is for parsing types, and used with the "ptype" command 319 so we can look up types that are qualified by scope, either with 320 the GDB "::" operator, or the Modula-2 '.' operator. */ 321 OP_TYPE, 322 323 /* An un-looked-up identifier. */ 324 OP_NAME, 325 326 /* An Objective C Foundation Class NSString constant */ 327 OP_OBJC_NSSTRING, 328 329 /* A F90 array range operator (for "exp:exp", "exp:", ":exp" and ":"). */ 330 OP_F90_RANGE, 331 332 /* OP_DECFLOAT is followed by a type pointer in the next exp_element 333 and a dec long constant value in the following exp_element. 334 Then comes another OP_DECFLOAT. */ 335 OP_DECFLOAT, 336 337 /* First extension operator. Individual language modules define 338 extra operators in *.inc include files below always starting with 339 numbering at OP_EXTENDED0: 340 BINOP_MOGRIFY = OP_EXTENDED0, 341 BINOP_FROB, 342 ... */ 343 OP_EXTENDED0, 344 345 /* Last possible extension operator. Defined to provide an 346 explicit and finite number of extended operators. */ 347 OP_EXTENDED_LAST = 0xff, 348 /* NOTE: Eventually, we expect to convert to an object-oriented 349 formulation for expression operators that does away with the 350 need for these extension operators, and indeed for this 351 entire enumeration type. Therefore, consider the OP_EXTENDED 352 definitions to be a temporary measure. */ 353 354 /* Each language specific set of operators starts at OP_EXTENDED0. */ 355 #include "ada-operator.inc" 356 357 /* Existing only to swallow the last comma (',') from last .inc file. */ 358 OP_UNUSED_LAST 359 }; 360 361 union exp_element 362 { 363 enum exp_opcode opcode; 364 struct symbol *symbol; 365 LONGEST longconst; 366 DOUBLEST doubleconst; 367 gdb_byte decfloatconst[16]; 368 /* Really sizeof (union exp_element) characters (or less for the last 369 element of a string). */ 370 char string; 371 struct type *type; 372 struct internalvar *internalvar; 373 struct block *block; 374 struct objfile *objfile; 375 }; 376 377 struct expression 378 { 379 const struct language_defn *language_defn; /* language it was entered in */ 380 struct gdbarch *gdbarch; /* architecture it was parsed in */ 381 int nelts; 382 union exp_element elts[1]; 383 }; 384 385 /* Macros for converting between number of expression elements and bytes 386 to store that many expression elements. */ 387 388 #define EXP_ELEM_TO_BYTES(elements) \ 389 ((elements) * sizeof (union exp_element)) 390 #define BYTES_TO_EXP_ELEM(bytes) \ 391 (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element)) 392 393 /* From parse.c */ 394 395 extern struct expression *parse_expression (char *); 396 397 extern struct type *parse_field_expression (char *, char **); 398 399 extern struct expression *parse_exp_1 (char **, struct block *, int); 400 401 /* For use by parsers; set if we want to parse an expression and 402 attempt to complete a field name. */ 403 extern int in_parse_field; 404 405 /* The innermost context required by the stack and register variables 406 we've encountered so far. To use this, set it to NULL, then call 407 parse_<whatever>, then look at it. */ 408 extern struct block *innermost_block; 409 410 /* From eval.c */ 411 412 /* Values of NOSIDE argument to eval_subexp. */ 413 414 enum noside 415 { 416 EVAL_NORMAL, 417 EVAL_SKIP, /* Only effect is to increment pos. */ 418 EVAL_AVOID_SIDE_EFFECTS /* Don't modify any variables or 419 call any functions. The value 420 returned will have the correct 421 type, and will have an 422 approximately correct lvalue 423 type (inaccuracy: anything that is 424 listed as being in a register in 425 the function in which it was 426 declared will be lval_register). */ 427 }; 428 429 extern struct value *evaluate_subexp_standard 430 (struct type *, struct expression *, int *, enum noside); 431 432 /* From expprint.c */ 433 434 extern void print_expression (struct expression *, struct ui_file *); 435 436 extern char *op_string (enum exp_opcode); 437 438 extern void dump_raw_expression (struct expression *, struct ui_file *, char *); 439 extern void dump_prefix_expression (struct expression *, struct ui_file *); 440 441 #endif /* !defined (EXPRESSION_H) */ 442