1 /* Definitions for expressions stored in reversed prefix form, for GDB. 2 Copyright 1986, 1989, 1992, 1994 Free Software Foundation, Inc. 3 4 This file is part of GDB. 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 19 20 #if !defined (EXPRESSION_H) 21 #define EXPRESSION_H 1 22 23 #ifdef __STDC__ 24 struct block; /* Forward declaration for prototypes */ 25 #endif 26 27 /* Definitions for saved C expressions. */ 28 29 /* An expression is represented as a vector of union exp_element's. 30 Each exp_element is an opcode, except that some opcodes cause 31 the following exp_element to be treated as a long or double constant 32 or as a variable. The opcodes are obeyed, using a stack for temporaries. 33 The value is left on the temporary stack at the end. */ 34 35 /* When it is necessary to include a string, 36 it can occupy as many exp_elements as it needs. 37 We find the length of the string using strlen, 38 divide to find out how many exp_elements are used up, 39 and skip that many. Strings, like numbers, are indicated 40 by the preceding opcode. */ 41 42 enum exp_opcode 43 { 44 /* Used when it's necessary to pass an opcode which will be ignored, 45 or to catch uninitialized values. */ 46 OP_NULL, 47 48 /* BINOP_... operate on two values computed by following subexpressions, 49 replacing them by one result value. They take no immediate arguments. */ 50 51 BINOP_ADD, /* + */ 52 BINOP_SUB, /* - */ 53 BINOP_MUL, /* * */ 54 BINOP_DIV, /* / */ 55 BINOP_REM, /* % */ 56 BINOP_MOD, /* mod (Knuth 1.2.4) */ 57 BINOP_LSH, /* << */ 58 BINOP_RSH, /* >> */ 59 BINOP_LOGICAL_AND, /* && */ 60 BINOP_LOGICAL_OR, /* || */ 61 BINOP_BITWISE_AND, /* & */ 62 BINOP_BITWISE_IOR, /* | */ 63 BINOP_BITWISE_XOR, /* ^ */ 64 BINOP_EQUAL, /* == */ 65 BINOP_NOTEQUAL, /* != */ 66 BINOP_LESS, /* < */ 67 BINOP_GTR, /* > */ 68 BINOP_LEQ, /* <= */ 69 BINOP_GEQ, /* >= */ 70 BINOP_REPEAT, /* @ */ 71 BINOP_ASSIGN, /* = */ 72 BINOP_COMMA, /* , */ 73 BINOP_SUBSCRIPT, /* x[y] */ 74 BINOP_EXP, /* Exponentiation */ 75 76 /* C++. */ 77 78 BINOP_MIN, /* <? */ 79 BINOP_MAX, /* >? */ 80 BINOP_SCOPE, /* :: */ 81 82 /* STRUCTOP_MEMBER is used for pointer-to-member constructs. 83 X . * Y translates into X STRUCTOP_MEMBER Y. */ 84 STRUCTOP_MEMBER, 85 86 /* STRUCTOP_MPTR is used for pointer-to-member constructs 87 when X is a pointer instead of an aggregate. */ 88 STRUCTOP_MPTR, 89 90 /* end of C++. */ 91 92 /* For Modula-2 integer division DIV */ 93 BINOP_INTDIV, 94 95 BINOP_ASSIGN_MODIFY, /* +=, -=, *=, and so on. 96 The following exp_element is another opcode, 97 a BINOP_, saying how to modify. 98 Then comes another BINOP_ASSIGN_MODIFY, 99 making three exp_elements in total. */ 100 101 /* Modula-2 standard (binary) procedures */ 102 BINOP_VAL, 103 BINOP_INCL, 104 BINOP_EXCL, 105 106 /* Concatenate two operands, such as character strings or bitstrings. 107 If the first operand is a integer expression, then it means concatenate 108 the second operand with itself that many times. */ 109 BINOP_CONCAT, 110 111 /* For Chill and Pascal. */ 112 BINOP_IN, /* Returns 1 iff ARG1 IN ARG2. */ 113 114 /* This is the "colon operator" used various places in Chill. */ 115 BINOP_RANGE, 116 117 /* This must be the highest BINOP_ value, for expprint.c. */ 118 BINOP_END, 119 120 /* Operates on three values computed by following subexpressions. */ 121 TERNOP_COND, /* ?: */ 122 123 /* A sub-string/sub-array. Chill syntax: OP1(OP2:OP3). 124 Return elements OP2 through OP3 of OP1. */ 125 TERNOP_SLICE, 126 127 /* A sub-string/sub-array. Chill syntax: OP1(OP2 UP OP3). 128 Return OP3 elements of OP1, starting with element OP2. */ 129 TERNOP_SLICE_COUNT, 130 131 /* Multidimensional subscript operator, such as Modula-2 x[a,b,...]. 132 The dimensionality is encoded in the operator, like the number of 133 function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>. 134 The value of the first following subexpression is subscripted 135 by each of the next following subexpressions, one per dimension. */ 136 MULTI_SUBSCRIPT, 137 138 /* The OP_... series take immediate following arguments. 139 After the arguments come another OP_... (the same one) 140 so that the grouping can be recognized from the end. */ 141 142 /* OP_LONG is followed by a type pointer in the next exp_element 143 and the long constant value in the following exp_element. 144 Then comes another OP_LONG. 145 Thus, the operation occupies four exp_elements. */ 146 OP_LONG, 147 148 /* OP_DOUBLE is similar but takes a DOUBLEST constant instead of a long. */ 149 OP_DOUBLE, 150 151 /* OP_VAR_VALUE takes one struct block * in the following element, 152 and one struct symbol * in the following exp_element, followed by 153 another OP_VAR_VALUE, making four exp_elements. If the block is 154 non-NULL, evaluate the symbol relative to the innermost frame 155 executing in that block; if the block is NULL use the selected frame. */ 156 OP_VAR_VALUE, 157 158 /* OP_LAST is followed by an integer in the next exp_element. 159 The integer is zero for the last value printed, 160 or it is the absolute number of a history element. 161 With another OP_LAST at the end, this makes three exp_elements. */ 162 OP_LAST, 163 164 /* OP_REGISTER is followed by an integer in the next exp_element. 165 This is the number of a register to fetch (as an int). 166 With another OP_REGISTER at the end, this makes three exp_elements. */ 167 OP_REGISTER, 168 169 /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element. 170 With another OP_INTERNALVAR at the end, this makes three exp_elements. */ 171 OP_INTERNALVAR, 172 173 /* OP_FUNCALL is followed by an integer in the next exp_element. 174 The integer is the number of args to the function call. 175 That many plus one values from following subexpressions 176 are used, the first one being the function. 177 The integer is followed by a repeat of OP_FUNCALL, 178 making three exp_elements. */ 179 OP_FUNCALL, 180 181 /* This is EXACTLY like OP_FUNCALL but is semantically different. 182 In F77, array subscript expressions, substring expressions 183 and function calls are all exactly the same syntactically. They may 184 only be dismabiguated at runtime. Thus this operator, which 185 indicates that we have found something of the form <name> ( <stuff> ) */ 186 OP_F77_UNDETERMINED_ARGLIST, 187 188 /* The following OP is a special one, it introduces a F77 complex 189 literal. It is followed by exactly two args that are doubles. */ 190 OP_COMPLEX, 191 192 /* OP_STRING represents a string constant. 193 Its format is the same as that of a STRUCTOP, but the string 194 data is just made into a string constant when the operation 195 is executed. */ 196 OP_STRING, 197 198 /* OP_BITSTRING represents a packed bitstring constant. 199 Its format is the same as that of a STRUCTOP, but the bitstring 200 data is just made into a bitstring constant when the operation 201 is executed. */ 202 OP_BITSTRING, 203 204 /* OP_ARRAY creates an array constant out of the following subexpressions. 205 It is followed by two exp_elements, the first containing an integer 206 that is the lower bound of the array and the second containing another 207 integer that is the upper bound of the array. The second integer is 208 followed by a repeat of OP_ARRAY, making four exp_elements total. 209 The bounds are used to compute the number of following subexpressions 210 to consume, as well as setting the bounds in the created array constant. 211 The type of the elements is taken from the type of the first subexp, 212 and they must all match. */ 213 OP_ARRAY, 214 215 /* UNOP_CAST is followed by a type pointer in the next exp_element. 216 With another UNOP_CAST at the end, this makes three exp_elements. 217 It casts the value of the following subexpression. */ 218 UNOP_CAST, 219 220 /* UNOP_MEMVAL is followed by a type pointer in the next exp_element 221 With another UNOP_MEMVAL at the end, this makes three exp_elements. 222 It casts the contents of the word addressed by the value of the 223 following subexpression. */ 224 UNOP_MEMVAL, 225 226 /* UNOP_... operate on one value from a following subexpression 227 and replace it with a result. They take no immediate arguments. */ 228 229 UNOP_NEG, /* Unary - */ 230 UNOP_LOGICAL_NOT, /* Unary ! */ 231 UNOP_COMPLEMENT, /* Unary ~ */ 232 UNOP_IND, /* Unary * */ 233 UNOP_ADDR, /* Unary & */ 234 UNOP_PREINCREMENT, /* ++ before an expression */ 235 UNOP_POSTINCREMENT, /* ++ after an expression */ 236 UNOP_PREDECREMENT, /* -- before an expression */ 237 UNOP_POSTDECREMENT, /* -- after an expression */ 238 UNOP_SIZEOF, /* Unary sizeof (followed by expression) */ 239 240 UNOP_PLUS, /* Unary plus */ 241 242 UNOP_CAP, /* Modula-2 standard (unary) procedures */ 243 UNOP_CHR, 244 UNOP_ORD, 245 UNOP_ABS, 246 UNOP_FLOAT, 247 UNOP_HIGH, 248 UNOP_MAX, 249 UNOP_MIN, 250 UNOP_ODD, 251 UNOP_TRUNC, 252 253 /* Chill builtin functions. */ 254 UNOP_LOWER, UNOP_UPPER, UNOP_LENGTH, UNOP_CARD, UNOP_CHMAX, UNOP_CHMIN, 255 256 OP_BOOL, /* Modula-2 builtin BOOLEAN type */ 257 OP_M2_STRING, /* Modula-2 string constants */ 258 259 /* STRUCTOP_... operate on a value from a following subexpression 260 by extracting a structure component specified by a string 261 that appears in the following exp_elements (as many as needed). 262 STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->". 263 They differ only in the error message given in case the value is 264 not suitable or the structure component specified is not found. 265 266 The length of the string follows the opcode, followed by 267 BYTES_TO_EXP_ELEM(length) elements containing the data of the 268 string, followed by the length again and the opcode again. */ 269 270 STRUCTOP_STRUCT, 271 STRUCTOP_PTR, 272 273 274 /* C++ */ 275 /* OP_THIS is just a placeholder for the class instance variable. 276 It just comes in a tight (OP_THIS, OP_THIS) pair. */ 277 OP_THIS, 278 279 /* OP_SCOPE surrounds a type name and a field name. The type 280 name is encoded as one element, but the field name stays as 281 a string, which, of course, is variable length. */ 282 OP_SCOPE, 283 284 /* Used to represent named structure field values in brace initializers 285 (or tuples as they are called in Chill). 286 The gcc C syntax is NAME:VALUE or .NAME=VALUE, the Chill syntax is 287 .NAME:VALUE. Multiple labels (as in the Chill syntax 288 .NAME1,.NAME2:VALUE) is represented as if it were 289 .NAME1:(.NAME2:VALUE) (though that is not valid Chill syntax). 290 291 The NAME is represented as for STRUCTOP_STRUCT; VALUE follows. */ 292 OP_LABELED, 293 294 /* OP_TYPE is for parsing types, and used with the "ptype" command 295 so we can look up types that are qualified by scope, either with 296 the GDB "::" operator, or the Modula-2 '.' operator. */ 297 OP_TYPE, 298 299 /* An un-looked-up identifier. */ 300 OP_NAME, 301 302 /* An unparsed expression. Used for Scheme (for now at least) */ 303 OP_EXPRSTRING 304 }; 305 306 union exp_element 307 { 308 enum exp_opcode opcode; 309 struct symbol *symbol; 310 LONGEST longconst; 311 DOUBLEST doubleconst; 312 /* Really sizeof (union exp_element) characters (or less for the last 313 element of a string). */ 314 char string; 315 struct type *type; 316 struct internalvar *internalvar; 317 struct block *block; 318 }; 319 320 struct expression 321 { 322 const struct language_defn *language_defn; /* language it was entered in */ 323 int nelts; 324 union exp_element elts[1]; 325 }; 326 327 /* Macros for converting between number of expression elements and bytes 328 to store that many expression elements. */ 329 330 #define EXP_ELEM_TO_BYTES(elements) \ 331 ((elements) * sizeof (union exp_element)) 332 #define BYTES_TO_EXP_ELEM(bytes) \ 333 (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element)) 334 335 /* From parse.c */ 336 337 extern struct expression *parse_expression PARAMS ((char *)); 338 339 extern struct expression *parse_exp_1 PARAMS ((char **, struct block *, int)); 340 341 /* The innermost context required by the stack and register variables 342 we've encountered so far. To use this, set it to NULL, then call 343 parse_<whatever>, then look at it. */ 344 extern struct block *innermost_block; 345 346 /* From eval.c */ 347 348 /* Values of NOSIDE argument to eval_subexp. */ 349 350 enum noside 351 { 352 EVAL_NORMAL, 353 EVAL_SKIP, /* Only effect is to increment pos. */ 354 EVAL_AVOID_SIDE_EFFECTS /* Don't modify any variables or 355 call any functions. The value 356 returned will have the correct 357 type, and will have an 358 approximately correct lvalue 359 type (inaccuracy: anything that is 360 listed as being in a register in 361 the function in which it was 362 declared will be lval_register). */ 363 }; 364 365 extern struct value* evaluate_subexp_standard 366 PARAMS ((struct type *, struct expression *, int*, enum noside)); 367 368 /* From expprint.c */ 369 370 extern void print_expression PARAMS ((struct expression *, GDB_FILE *)); 371 372 extern char *op_string PARAMS ((enum exp_opcode)); 373 374 /* To enable dumping of all parsed expressions in a human readable 375 form, define DEBUG_EXPRESSIONS. This is a compile time constant 376 at the moment, since it's not clear that this feature is important 377 enough to include by default. */ 378 379 #ifdef DEBUG_EXPRESSIONS 380 extern void dump_expression PARAMS ((struct expression *, GDB_FILE *, char *)); 381 #define DUMP_EXPRESSION(exp,file,note) dump_expression ((exp), (file), (note)) 382 #else 383 #define DUMP_EXPRESSION(exp,file,note) /* Null expansion */ 384 #endif /* DEBUG_EXPRESSIONS */ 385 386 #endif /* !defined (EXPRESSION_H) */ 387