1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
|
/*
Copyright 2024 Northern.tech AS
This file is part of CFEngine 3 - written and maintained by Northern.tech AS.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; version 3.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
To the extent this program is licensed as part of the Enterprise
versions of CFEngine, the applicable Commercial Open Source License
(COSL) may apply to this file if you as a licensee so wish it. See
included file COSL.txt.
*/
#ifndef CFENGINE_LOGIC_EXPRESSIONS_H
#define CFENGINE_LOGIC_EXPRESSIONS_H
#include <stdbool.h>
#include <string_expressions.h>
/*
Logic expressions grammar:
<expr> ::= <or-expr>
<or-expr> ::= <and-expr>
<and-expr> | <and-expr>
<and-expr> || <and-expr>
<and-expr> ::= <not-expr>
<not-expr> . <not-expr>
<not-expr> & <not-expr>
<not-expr> ::= ! <primary>
<primary>
<primary> ::= ( <expr> )
<name>
Basis of logic evaluation is <name> values which are provided by
StringExpression and suitable string->bool evaluator.
*/
typedef enum
{
LOGICAL_OP_OR,
LOGICAL_OP_AND,
LOGICAL_OP_NOT,
LOGICAL_OP_EVAL
} LogicalOp;
typedef struct Expression_ Expression;
struct Expression_
{
LogicalOp op;
union
{
struct
{
Expression *lhs;
Expression *rhs;
} andor;
struct
{
Expression *arg;
} not;
struct
{
StringExpression *name;
} eval;
} val;
};
/* Parsing and evaluation */
/*
* Result of parsing.
*
* if succeeded, then result is the result of parsing and position is last
* character consumed.
*
* if not succeeded, then result is NULL and position is last character consumed
* before the error.
*/
typedef struct
{
Expression *result;
int position;
} ParseResult;
ParseResult ParseExpression(const char *expr, int start, int end);
typedef enum ExpressionValue
{
EXPRESSION_VALUE_ERROR = -1,
EXPRESSION_VALUE_FALSE = false,
EXPRESSION_VALUE_TRUE = true,
} ExpressionValue;
/*
* Evaluator should return FALSE, TRUE or ERROR if unable to parse result. In
* later case evaluation will be aborted and ERROR will be returned from
* EvalExpression.
*/
typedef ExpressionValue(*NameEvaluator) (const char *name, void *param);
/*
* Result is heap-allocated. In case evalfn() returns ERROR whole
* EvalExpression returns ERROR as well.
*/
ExpressionValue EvalExpression(const Expression *expr,
NameEvaluator nameevalfn, VarRefEvaluator varrefevalfn, void *param);
/*
* Frees Expression produced by ParseExpression. NULL-safe.
*/
void FreeExpression(Expression *expr);
#endif
|
