| 1 | /* Definitions for expressions stored in reversed prefix form, for GDB. |
| 2 | Copyright (C) 1986, 1989 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 6 | GDB 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 1, or (at your option) |
| 9 | any later version. |
| 10 | |
| 11 | GDB 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 GDB; see the file COPYING. If not, write to |
| 18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ |
| 19 | |
| 20 | /* Definitions for saved C expressions. */ |
| 21 | |
| 22 | /* An expression is represented as a vector of union exp_element's. |
| 23 | Each exp_element is an opcode, except that some opcodes cause |
| 24 | the following exp_element to be treated as a long or double constant |
| 25 | or as a variable. The opcodes are obeyed, using a stack for temporaries. |
| 26 | The value is left on the temporary stack at the end. */ |
| 27 | |
| 28 | /* When it is necessary to include a string, |
| 29 | it can occupy as many exp_elements as it needs. |
| 30 | We find the length of the string using strlen, |
| 31 | divide to find out how many exp_elements are used up, |
| 32 | and skip that many. Strings, like numbers, are indicated |
| 33 | by the preceding opcode. */ |
| 34 | |
| 35 | enum exp_opcode |
| 36 | { |
| 37 | /* BINOP_... operate on two values computed by following subexpressions, |
| 38 | replacing them by one result value. They take no immediate arguments. */ |
| 39 | BINOP_ADD, /* + */ |
| 40 | BINOP_SUB, /* - */ |
| 41 | BINOP_MUL, /* * */ |
| 42 | BINOP_DIV, /* / */ |
| 43 | BINOP_REM, /* % */ |
| 44 | BINOP_LSH, /* << */ |
| 45 | BINOP_RSH, /* >> */ |
| 46 | BINOP_AND, /* && */ |
| 47 | BINOP_OR, /* || */ |
| 48 | BINOP_LOGAND, /* & */ |
| 49 | BINOP_LOGIOR, /* | */ |
| 50 | BINOP_LOGXOR, /* ^ */ |
| 51 | BINOP_EQUAL, /* == */ |
| 52 | BINOP_NOTEQUAL, /* != */ |
| 53 | BINOP_LESS, /* < */ |
| 54 | BINOP_GTR, /* > */ |
| 55 | BINOP_LEQ, /* <= */ |
| 56 | BINOP_GEQ, /* >= */ |
| 57 | BINOP_REPEAT, /* @ */ |
| 58 | BINOP_ASSIGN, /* = */ |
| 59 | BINOP_COMMA, /* , */ |
| 60 | BINOP_SUBSCRIPT, /* x[y] */ |
| 61 | BINOP_EXP, /* Exponentiation */ |
| 62 | |
| 63 | /* C++. */ |
| 64 | BINOP_MIN, /* <? */ |
| 65 | BINOP_MAX, /* >? */ |
| 66 | BINOP_SCOPE, /* :: */ |
| 67 | |
| 68 | /* STRUCTOP_MEMBER is used for pointer-to-member constructs. |
| 69 | X . * Y translates into X STRUCTOP_MEMBER Y. */ |
| 70 | STRUCTOP_MEMBER, |
| 71 | /* STRUCTOP_MPTR is used for pointer-to-member constructs |
| 72 | when X is a pointer instead of an aggregate. */ |
| 73 | STRUCTOP_MPTR, |
| 74 | /* end of C++. */ |
| 75 | |
| 76 | BINOP_END, |
| 77 | |
| 78 | BINOP_ASSIGN_MODIFY, /* +=, -=, *=, and so on. |
| 79 | The following exp_element is another opcode, |
| 80 | a BINOP_, saying how to modify. |
| 81 | Then comes another BINOP_ASSIGN_MODIFY, |
| 82 | making three exp_elements in total. */ |
| 83 | |
| 84 | /* Operates on three values computed by following subexpressions. */ |
| 85 | TERNOP_COND, /* ?: */ |
| 86 | |
| 87 | /* The OP_... series take immediate following arguments. |
| 88 | After the arguments come another OP_... (the same one) |
| 89 | so that the grouping can be recognized from the end. */ |
| 90 | |
| 91 | /* OP_LONG is followed by a type pointer in the next exp_element |
| 92 | and the long constant value in the following exp_element. |
| 93 | Then comes another OP_LONG. |
| 94 | Thus, the operation occupies four exp_elements. */ |
| 95 | |
| 96 | OP_LONG, |
| 97 | /* OP_DOUBLE is similar but takes a double constant instead of a long one. */ |
| 98 | OP_DOUBLE, |
| 99 | /* OP_VAR_VALUE takes one struct symbol * in the following exp_element, |
| 100 | followed by another OP_VAR_VALUE, making three exp_elements. */ |
| 101 | OP_VAR_VALUE, |
| 102 | /* OP_LAST is followed by an integer in the next exp_element. |
| 103 | The integer is zero for the last value printed, |
| 104 | or it is the absolute number of a history element. |
| 105 | With another OP_LAST at the end, this makes three exp_elements. */ |
| 106 | OP_LAST, |
| 107 | /* OP_REGISTER is followed by an integer in the next exp_element. |
| 108 | This is the number of a register to fetch (as an int). |
| 109 | With another OP_REGISTER at the end, this makes three exp_elements. */ |
| 110 | OP_REGISTER, |
| 111 | /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element. |
| 112 | With another OP_INTERNALVAR at the end, this makes three exp_elements. */ |
| 113 | OP_INTERNALVAR, |
| 114 | /* OP_FUNCALL is followed by an integer in the next exp_element. |
| 115 | The integer is the number of args to the function call. |
| 116 | That many plus one values from following subexpressions |
| 117 | are used, the first one being the function. |
| 118 | The integer is followed by a repeat of OP_FUNCALL, |
| 119 | making three exp_elements. */ |
| 120 | OP_FUNCALL, |
| 121 | /* OP_STRING represents a string constant. |
| 122 | Its format is the same as that of a STRUCTOP, but the string |
| 123 | data is just made into a string constant when the operation |
| 124 | is executed. */ |
| 125 | OP_STRING, |
| 126 | |
| 127 | /* UNOP_CAST is followed by a type pointer in the next exp_element. |
| 128 | With another UNOP_CAST at the end, this makes three exp_elements. |
| 129 | It casts the value of the following subexpression. */ |
| 130 | UNOP_CAST, |
| 131 | /* UNOP_MEMVAL is followed by a type pointer in the next exp_element |
| 132 | With another UNOP_MEMVAL at the end, this makes three exp_elements. |
| 133 | It casts the contents of the word addressed by the value of the |
| 134 | following subexpression. */ |
| 135 | UNOP_MEMVAL, |
| 136 | /* UNOP_... operate on one value from a following subexpression |
| 137 | and replace it with a result. They take no immediate arguments. */ |
| 138 | UNOP_NEG, /* Unary - */ |
| 139 | UNOP_ZEROP, /* Unary ! */ |
| 140 | UNOP_LOGNOT, /* Unary ~ */ |
| 141 | UNOP_IND, /* Unary * */ |
| 142 | UNOP_ADDR, /* Unary & */ |
| 143 | UNOP_PREINCREMENT, /* ++ before an expression */ |
| 144 | UNOP_POSTINCREMENT, /* ++ after an expression */ |
| 145 | UNOP_PREDECREMENT, /* -- before an expression */ |
| 146 | UNOP_POSTDECREMENT, /* -- after an expression */ |
| 147 | UNOP_SIZEOF, /* Unary sizeof (followed by expression) */ |
| 148 | |
| 149 | /* STRUCTOP_... operate on a value from a following subexpression |
| 150 | by extracting a structure component specified by a string |
| 151 | that appears in the following exp_elements (as many as needed). |
| 152 | STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->". |
| 153 | They differ only in the error message given in case the value is |
| 154 | not suitable or the structure component specified is not found. |
| 155 | |
| 156 | The length of the string follows in the next exp_element, |
| 157 | (after the string), followed by another STRUCTOP_... code. */ |
| 158 | STRUCTOP_STRUCT, |
| 159 | STRUCTOP_PTR, |
| 160 | |
| 161 | /* C++ */ |
| 162 | /* OP_THIS is just a placeholder for the class instance variable. |
| 163 | It just comes in a tight (OP_THIS, OP_THIS) pair. */ |
| 164 | OP_THIS, |
| 165 | |
| 166 | /* OP_SCOPE surrounds a type name and a field name. The type |
| 167 | name is encoded as one element, but the field name stays as |
| 168 | a string, which, of course, is variable length. */ |
| 169 | OP_SCOPE, |
| 170 | |
| 171 | }; |
| 172 | |
| 173 | union exp_element |
| 174 | { |
| 175 | enum exp_opcode opcode; |
| 176 | struct symbol *symbol; |
| 177 | LONGEST longconst; |
| 178 | double doubleconst; |
| 179 | char string; |
| 180 | struct type *type; |
| 181 | struct internalvar *internalvar; |
| 182 | }; |
| 183 | |
| 184 | struct expression |
| 185 | { |
| 186 | int nelts; |
| 187 | union exp_element elts[1]; |
| 188 | }; |
| 189 | |
| 190 | struct expression *parse_c_expression (); |
| 191 | struct expression *parse_c_1 (); |