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comparison lwlink/expr.h @ 139:106c2fe3c9d9

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repo reorg
author lost
date Wed, 28 Jan 2009 05:59:14 +0000
parents lwlink-old/trunk/src/expr.h@050864a47b38
children 299c5d793aca
comparison
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138:050864a47b38 139:106c2fe3c9d9
1 /*
2 expr.h
3 Copyright © 2009 William Astle
4
5 This file is part of LWLINK.
6
7 LWLINK is free software: you can redistribute it and/or modify it under the
8 terms of the GNU General Public License as published by the Free Software
9 Foundation, either version 3 of the License, or (at your option) any later
10 version.
11
12 This program is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 more details.
16
17 You should have received a copy of the GNU General Public License along with
18 this program. If not, see <http://www.gnu.org/licenses/>.
19 */
20
21 /*
22 Definitions for expression evaluator
23 */
24
25 #ifndef __expr_h_seen__
26 #define __expr_h_seen__
27
28 #ifndef __expr_c_seen__
29 #define __expr_E__ extern
30 #else
31 #define __expr_E__
32 #endif
33
34 // term types
35 #define LW_TERM_NONE 0
36 #define LW_TERM_OPER 1 // an operator
37 #define LW_TERM_INT 2 // 32 bit signed integer
38 #define LW_TERM_SYM 3 // symbol reference
39
40 // operator types
41 #define LW_OPER_NONE 0
42 #define LW_OPER_PLUS 1 // +
43 #define LW_OPER_MINUS 2 // -
44 #define LW_OPER_TIMES 3 // *
45 #define LW_OPER_DIVIDE 4 // /
46 #define LW_OPER_MOD 5 // %
47 #define LW_OPER_INTDIV 6 // \ (don't end line with \)
48 #define LW_OPER_BWAND 7 // bitwise AND
49 #define LW_OPER_BWOR 8 // bitwise OR
50 #define LW_OPER_BWXOR 9 // bitwise XOR
51 #define LW_OPER_AND 10 // boolean AND
52 #define LW_OPER_OR 11 // boolean OR
53 #define LW_OPER_NEG 12 // - unary negation (2's complement)
54 #define LW_OPER_COM 13 // ^ unary 1's complement
55
56
57 // term structure
58 typedef struct lw_expr_term_s
59 {
60 int term_type; // type of term (see above)
61 char *symbol; // name of a symbol
62 int value; // value of the term (int) or operator number (OPER)
63 } lw_expr_term_t;
64
65 // type for an expression evaluation stack
66 typedef struct lw_expr_stack_node_s lw_expr_stack_node_t;
67 struct lw_expr_stack_node_s
68 {
69 lw_expr_term_t *term;
70 lw_expr_stack_node_t *prev;
71 lw_expr_stack_node_t *next;
72 };
73
74 typedef struct lw_expr_stack_s
75 {
76 lw_expr_stack_node_t *head;
77 lw_expr_stack_node_t *tail;
78 } lw_expr_stack_t;
79
80 __expr_E__ void lw_expr_term_free(lw_expr_term_t *t);
81 __expr_E__ lw_expr_term_t *lw_expr_term_create_oper(int oper);
82 __expr_E__ lw_expr_term_t *lw_expr_term_create_sym(char *sym, int symtype);
83 __expr_E__ lw_expr_term_t *lw_expr_term_create_int(int val);
84 __expr_E__ lw_expr_term_t *lw_expr_term_dup(lw_expr_term_t *t);
85
86 __expr_E__ void lw_expr_stack_free(lw_expr_stack_t *s);
87 __expr_E__ lw_expr_stack_t *lw_expr_stack_create(void);
88
89 __expr_E__ void lw_expr_stack_push(lw_expr_stack_t *s, lw_expr_term_t *t);
90 __expr_E__ lw_expr_term_t *lw_expr_stack_pop(lw_expr_stack_t *s);
91
92 // simplify expression
93 __expr_E__ int lw_expr_reval(lw_expr_stack_t *s, lw_expr_stack_t *(*sfunc)(char *sym, int symtype, void *state), void *state);
94
95 // useful macros
96 // is the expression "simple" (one term)?
97 #define lw_expr_is_simple(s) ((s) -> head == (s) -> tail)
98
99 // is the expression constant?
100 #define lw_expr_is_constant(s) (lw_expr_is_simple(s) && (!((s) -> head) || (s) -> head -> term -> term_type == LW_TERM_INT))
101
102 // get the constant value of an expression or 0 if not constant
103 #define lw_expr_get_value(s) (lw_expr_is_constant(s) ? ((s) -> head ? (s) -> head -> term -> value : 0) : 0)
104
105 #undef __expr_E__
106
107 #endif // __expr_h_seen__