gdb/expression.h

   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., 675 Mass Ave, Cambridge, MA 02139, 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 must be the highest BINOP_ value, for expprint.c.  */
 115   BINOP_END,
 116
 117   /* Operates on three values computed by following subexpressions.  */
 118   TERNOP_COND,          /* ?: */
 119
 120   /* A sub-string/sub-array.  Chill syntax:  OP1(OP2:OP3).
 121      Return elements OP2 through OP3 of OP1.  */
 122   TERNOP_SLICE,
 123
 124   /* A sub-string/sub-array.  Chill syntax:  OP1(OP2 UP OP3).
 125      Return OP3 elements of OP1, starting with element OP2. */
 126   TERNOP_SLICE_COUNT,
 127
 128   /* Multidimensional subscript operator, such as Modula-2 x[a,b,...].
 129      The dimensionality is encoded in the operator, like the number of
 130      function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>.
 131      The value of the first following subexpression is subscripted
 132      by each of the next following subexpressions, one per dimension. */
 133    MULTI_SUBSCRIPT,
 134
 135   /* For Fortran array subscripting (column major style). Like the
 136      Modula operator, we find that the dimensionality is
 137      encoded in the operator.  This operator is distinct
 138      from the above one because it uses column-major array
 139      ordering not row-major.  */
 140   MULTI_F77_SUBSCRIPT,
 141
 142   /* The OP_... series take immediate following arguments.
 143      After the arguments come another OP_... (the same one)
 144      so that the grouping can be recognized from the end.  */
 145
 146   /* OP_LONG is followed by a type pointer in the next exp_element
 147      and the long constant value in the following exp_element.
 148      Then comes another OP_LONG.
 149      Thus, the operation occupies four exp_elements.  */
 150   OP_LONG,
 151
 152   /* OP_DOUBLE is similar but takes a double constant instead of a long.  */
 153   OP_DOUBLE,
 154
 155   /* OP_VAR_VALUE takes one struct block * in the following element,
 156      and one struct symbol * in the following exp_element, followed by
 157      another OP_VAR_VALUE, making four exp_elements.  If the block is
 158      non-NULL, evaluate the symbol relative to the innermost frame
 159      executing in that block; if the block is NULL use the selected frame.  */
 160   OP_VAR_VALUE,
 161
 162   /* OP_LAST is followed by an integer in the next exp_element.
 163      The integer is zero for the last value printed,
 164      or it is the absolute number of a history element.
 165      With another OP_LAST at the end, this makes three exp_elements.  */
 166   OP_LAST,
 167
 168   /* OP_REGISTER is followed by an integer in the next exp_element.
 169      This is the number of a register to fetch (as an int).
 170      With another OP_REGISTER at the end, this makes three exp_elements.  */
 171   OP_REGISTER,
 172
 173   /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
 174      With another OP_INTERNALVAR at the end, this makes three exp_elements.  */
 175   OP_INTERNALVAR,
 176
 177   /* OP_FUNCALL is followed by an integer in the next exp_element.
 178      The integer is the number of args to the function call.
 179      That many plus one values from following subexpressions
 180      are used, the first one being the function.
 181      The integer is followed by a repeat of OP_FUNCALL,
 182      making three exp_elements.  */
 183   OP_FUNCALL,
 184
 185   /* This is EXACTLY like OP_FUNCALL but is semantically different.
 186      In F77, array subscript expressions, substring expressions
 187      and function calls are  all exactly the same syntactically. They may
 188      only be dismabiguated at runtime.  Thus this operator, which
 189      indicates that we have found something of the form <name> ( <stuff> ) */
 190   OP_F77_UNDETERMINED_ARGLIST,
 191
 192   /* The following OP is a special one, it introduces a F77 complex
 193      literal. It is followed by exactly two args that are doubles.  */
 194   OP_COMPLEX,
 195
 196   /* The following OP introduces a F77 substring operator.
 197      It should have a string type and two integer types that follow
 198      indicating the "from" and "to" for the substring. */
 199   OP_F77_SUBSTR,
 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_... operate on one value from a following subexpression
 236      and replace it with a result.  They take no immediate arguments.  */
 237
 238   UNOP_NEG,             /* Unary - */
 239   UNOP_LOGICAL_NOT,     /* Unary ! */
 240   UNOP_COMPLEMENT,      /* Unary ~ */
 241   UNOP_IND,             /* Unary * */
 242   UNOP_ADDR,            /* Unary & */
 243   UNOP_PREINCREMENT,    /* ++ before an expression */
 244   UNOP_POSTINCREMENT,   /* ++ after an expression */
 245   UNOP_PREDECREMENT,    /* -- before an expression */
 246   UNOP_POSTDECREMENT,   /* -- after an expression */
 247   UNOP_SIZEOF,          /* Unary sizeof (followed by expression) */
 248
 249   UNOP_PLUS,            /* Unary plus */
 250
 251   UNOP_CAP,             /* Modula-2 standard (unary) procedures */
 252   UNOP_CHR,
 253   UNOP_ORD,
 254   UNOP_ABS,
 255   UNOP_FLOAT,
 256   UNOP_HIGH,
 257   UNOP_MAX,
 258   UNOP_MIN,
 259   UNOP_ODD,
 260   UNOP_TRUNC,
 261
 262   OP_BOOL,              /* Modula-2 builtin BOOLEAN type */
 263   OP_M2_STRING,         /* Modula-2 string constants */
 264
 265   /* STRUCTOP_... operate on a value from a following subexpression
 266      by extracting a structure component specified by a string
 267      that appears in the following exp_elements (as many as needed).
 268      STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
 269      They differ only in the error message given in case the value is
 270      not suitable or the structure component specified is not found.
 271
 272      The length of the string follows the opcode, followed by
 273      BYTES_TO_EXP_ELEM(length) elements containing the data of the
 274      string, followed by the length again and the opcode again.  */
 275
 276   STRUCTOP_STRUCT,
 277   STRUCTOP_PTR,
 278
 279   /* C++ */
 280   /* OP_THIS is just a placeholder for the class instance variable.
 281      It just comes in a tight (OP_THIS, OP_THIS) pair.  */
 282   OP_THIS,
 283
 284   /* OP_SCOPE surrounds a type name and a field name.  The type
 285      name is encoded as one element, but the field name stays as
 286      a string, which, of course, is variable length.  */
 287   OP_SCOPE,
 288
 289   /* Used to represent named structure field values in brace initializers
 290      (or tuples as they are called in Chill).
 291      The gcc C syntax is NAME:VALUE or .NAME=VALUE, the Chill syntax is
 292      .NAME:VALUE.  Multiple labels (as in the Chill syntax
 293      .NAME1,.NAME2:VALUE) is represented as if it were
 294      .NAME1:(.NAME2:VALUE) (though that is not valid Chill syntax).
 295
 296      The NAME is represented as for STRUCTOP_STRUCT;  VALUE follows. */
 297   OP_LABELED,
 298
 299   /* OP_TYPE is for parsing types, and used with the "ptype" command
 300      so we can look up types that are qualified by scope, either with
 301      the GDB "::" operator, or the Modula-2 '.' operator. */
 302   OP_TYPE
 303 };
 304
 305 union exp_element
 306 {
 307   enum exp_opcode opcode;
 308   struct symbol *symbol;
 309   LONGEST longconst;
 310   double doubleconst;
 311   /* Really sizeof (union exp_element) characters (or less for the last
 312      element of a string).  */
 313   char string;
 314   struct type *type;
 315   struct internalvar *internalvar;
 316   struct block *block;
 317 };
 318
 319 struct expression
 320 {
 321   const struct language_defn *language_defn;  /* language it was entered in */
 322   int nelts;
 323   union exp_element elts[1];
 324 };
 325
 326 /* Macros for converting between number of expression elements and bytes
 327    to store that many expression elements. */
 328
 329 #define EXP_ELEM_TO_BYTES(elements) \
 330     ((elements) * sizeof (union exp_element))
 331 #define BYTES_TO_EXP_ELEM(bytes) \
 332     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 333
 334 /* From parse.c */
 335
 336 extern struct expression *parse_expression PARAMS ((char *));
 337
 338 extern struct expression *parse_exp_1 PARAMS ((char **, struct block *, int));
 339
 340 /* The innermost context required by the stack and register variables
 341    we've encountered so far.  To use this, set it to NULL, then call
 342    parse_<whatever>, then look at it.  */
 343 extern struct block *innermost_block;
 344
 345 /* From expprint.c */
 346
 347 extern void print_expression PARAMS ((struct expression *, GDB_FILE *));
 348
 349 extern char *op_string PARAMS ((enum exp_opcode));
 350
 351 /* To enable dumping of all parsed expressions in a human readable
 352    form, define DEBUG_EXPRESSIONS.  This is a compile time constant
 353    at the moment, since it's not clear that this feature is important
 354    enough to include by default. */
 355
 356 #ifdef DEBUG_EXPRESSIONS
 357 extern void dump_expression PARAMS ((struct expression *, GDB_FILE *, char *));
 358 #define DUMP_EXPRESSION(exp,file,note) dump_expression ((exp), (file), (note))
 359 #else
 360 #define DUMP_EXPRESSION(exp,file,note)  /* Null expansion */
 361 #endif  /* DEBUG_EXPRESSIONS */
 362
 363 #endif  /* !defined (EXPRESSION_H) */