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1 | /* Definitions for expressions stored in reversed prefix form, for GDB. |
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2 | Copyright (C) 1986, 1989 Free Software Foundation, Inc. |
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3 | |
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4 | This file is part of GDB. |
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5 | |
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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. |
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10 | |
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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. */ |
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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 */ |
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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 | |
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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, |
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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 | |
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171 | }; |
172 | |
173 | union exp_element |
174 | { |
175 | enum exp_opcode opcode; |
176 | struct symbol *symbol; |
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177 | LONGEST longconst; |
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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 (); |