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Started creating expression parser
author lost
date Thu, 23 Oct 2008 03:37:48 +0000
parents src/expr.h@b28d7cb60779
children 4f14eae64d38
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14:b28d7cb60779 15:1f598d89b9b0
1 /*
2 lwval.h
3 Copyright © 2008 William Astle
4
5 This file is part of LWASM.
6
7 LWASM 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 This file contains definitions associated with the expression evaluator used
23 by LWASM.
24
25 The core of the entire expression handler is the opaque type LWVAL, pointers
26 to which are passed around to keep track of values. A value may be a simple
27 integer or it could be a more complex expression linked by operators or it
28 could be a polynomial expression. Simple integers are merely a degenerate
29 case of polynomials.
30
31 The package understands the following operations:
32
33 addition
34 subtraction
35 multiplication
36 division
37 modulus
38 parentheses
39 unary negation
40 unary "positive"
41 bitwise and
42 bitwise or
43 bitwise not (1's complement)
44 bitwise exclusive or
45
46 Infix operators can be expressed as LWVAL <op> LWVAL. Thus, the order of
47 operations is only relevant when initially parsing the expression. The order
48 of evaluation is determined by what appears on either side of the <op> as
49 an LWVAL may be an expression.
50 */
51
52 #ifndef __lwval_h_seen__
53 #define __lwval_h_seen__
54
55 typedef struct lwval LWVAL;
56
57 struct lwval_dt_expr
58 {
59 LWVAL *v1; // first value
60 LWVAL *v2; // second value
61 int op; // operator
62 };
63
64 union lwval_dt
65 {
66 int lwval_int; // integer type data
67 char *lwval_var; // pointer to variable name
68 struct lwval_dt_expr expr; // expression
69 };
70
71 enum
72 {
73 LWVAL_TYPE_UNDEF, // undefined
74 LWVAL_TYPE_NAN, // not a number
75 LWVAL_TYPE_INT, // integer
76 LWVAL_TYPE_VAR, // variable (symbol)
77 LWVAL_TYPE_EXPR, // expression
78 LWVAL_TYPE_ERR // error
79 };
80
81 struct lwval
82 {
83 int lwval_type; // data type
84 union lwval_dt dt; // type specific stuff
85 };
86
87 #ifndef __lwval_c_seen__
88 #define EE extern
89 #else
90 #define EE
91 #endif
92
93 EE LWVAL *lwval_construct_int(int value);
94 EE LWVAL *lwval_construct_err(int errno);
95 EE LWVAL *lwval_construct_nan(void);
96 EE LWVAL *lwval_construct_expr(LWVAL *v1, LWVAL *v2, int op);
97 EE LWVAL *lwval_construct_undef(void);
98 EE void lwval_clear(LWVAL *value);
99 EE void lwval_destroy(LWVAL *value);
100 EE void lwval_dup(LWVAL *v1, LWVAL *v2);
101
102 // operators - operate on v1 and v2 in order, result goes into
103 // v1; return v1
104 EE LWVAL *lwval_add(LWVAL *v1, LWVAL *v2);
105 EE LWVAL *lwval_sub(LWVAL *v1, LWVAL *v2);
106 EE LWVAL *lwval_mul(LWVAL *v1, LWVAL *v2);
107 EE LWVAL *lwval_div(LWVAL *v1, LWVAL *v2);
108 EE LWVAL *lwval_mod(LWVAL *v1, LWVAL *v2);
109 EE LWVAL *lwval_neg(LWVAL *v1);
110
111 #endif //__lwval_h_seen__