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
|
/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This file is part of the Java Expressions Library (JEL).
* For more information about JEL visit : http://fti.dn.ua/JEL/
*
* Copyright (C) 1998, 1999, 2000, 2001, 2003, 2006, 2007, 2009 Konstantin L. Metlov
*
* 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, either version 3 of the License, or
* (at your option) any later version.
*
* 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, see <http://www.gnu.org/licenses/>.
*/
public class YourTestBed {
public static void main(String[] args) throws Throwable {
//**********************************************************
//**** to use JEL we first have to define the namespace ****
// we shall export the static methods of java.lang.Math
Class<?>[] stLib=new Class<?>[1];
stLib[0]=java.lang.Math.class;
// we shall enable access to methods of two classes
Class<?>[] dynLib=new Class<?>[2];
// we export global context fields/methods
dynLib[0]=GlobalContext.class;
// we export YYY getXXXProperty() methods for dynamic variable access
dynLib[1]=DVResolverProvider.class;
// this initializes the resolver object
DVResolverProvider resolver=new DVResolverProvider();
// we shall allow dot operators on strings and data
Class<?>[] dotLib=new Class<?>[2];
dotLib[0]=Data.class;
dotLib[1]=java.lang.String.class;
// finally, the namespace is defined by constructing the library class
gnu.jel.Library lib=
new gnu.jel.Library(stLib,dynLib,dotLib,resolver,null);
//**********************************************************
//******** Now we setup the global context and data *******
Object[] context=new Object[2];
GlobalContext gc=new GlobalContext(0.2,new Data(2),new Data(10));
context[0]=gc;
context[1]=resolver; // this pointer for YYY getXXXProperty() methos
//**********************************************************
//******** We are ready to compile some expressions *******
gnu.jel.CompiledExpression expr;
// constant expression
expr=gnu.jel.Evaluator.compile("2*2",lib);
System.out.println("2*2="+expr.evaluate(context));
// expression accessing the variables
expr=gnu.jel.Evaluator.compile("x",lib);
System.out.println("x="+expr.evaluate(context));
// three expressions accessing the variables with dot operator
expr=gnu.jel.Evaluator.compile("d1.value",lib);
System.out.println("d1.value="+expr.evaluate(context));
//
expr=gnu.jel.Evaluator.compile("d2.value",lib);
System.out.println("d2.value="+expr.evaluate(context));
//
expr=gnu.jel.Evaluator.compile("(d1.value+d2.value)*x*10",lib);
System.out.println("(d1.value+d2.value)*x*10="+expr.evaluate(context));
// also using static functions
expr=gnu.jel.Evaluator.compile("round((d1.value+d2.value)*x*10)",lib);
System.out.println("round((d1.value+d2.value)*x*10)="+expr.evaluate(context));
// LET's try dynamic variables
// First, we add few _DYNAMICALLY_, this can (and intended to) be
// done after the gnu.jel.Library initialization
resolver.addProperty("sDvar","str1");
resolver.addProperty("dataDvar",new Data(3));
// now we can access them
expr=gnu.jel.Evaluator.compile("sDvar",lib);
System.out.println("sDvar="+expr.evaluate(context));
expr=gnu.jel.Evaluator.compile("dataDvar",lib);
System.out.println("dataDvar="+expr.evaluate(context));
// it is possible to have hierarchical name space
// let's add a second level of hierarchy
resolver.addProperty("sDvar.data1",new Data(5));
resolver.addProperty("sDvar.data2",new Data(6));
resolver.addProperty("sDvar.str","This is string");
// we can access these also
expr=gnu.jel.Evaluator.compile("sDvar.data1",lib);
System.out.println("sDvar.data1="+expr.evaluate(context));
expr=gnu.jel.Evaluator.compile("sDvar.str",lib);
System.out.println("sDvar.str="+expr.evaluate(context));
expr=gnu.jel.Evaluator.compile("sDvar.data2",lib);
System.out.println("sDvar.data2="+expr.evaluate(context));
// they are ready for calculations
expr=gnu.jel.Evaluator.compile("sDvar.data1+sDvar.data2+1",lib);
System.out.println("sDvar.data1+sDvar.data2+1="+expr.evaluate(context));
// You can add more expressions here
};
};
|
