1 |
| |
2 |
| |
3 |
| |
4 |
| |
5 |
| |
6 |
| |
7 |
| |
8 |
| |
9 |
| |
10 |
| |
11 |
| |
12 |
| |
13 |
| |
14 |
| |
15 |
| package org.apache.hivemind.conditional; |
16 |
| |
17 |
| import org.apache.hivemind.util.Defense; |
18 |
| |
19 |
| |
20 |
| |
21 |
| |
22 |
| |
23 |
| |
24 |
| |
25 |
| |
26 |
| public class Parser |
27 |
| { |
28 |
| private String _input; |
29 |
| |
30 |
| private Lexer _lexer; |
31 |
| |
32 |
| private Token _nextToken; |
33 |
| |
34 |
| private boolean _onDeck; |
35 |
| |
36 |
| |
37 |
| |
38 |
| |
39 |
| private static final Evaluator NOT_EVALUATOR = new NotEvaluator(); |
40 |
| |
41 |
| private static final Evaluator OR_EVALUATOR = new OrEvaluator(); |
42 |
| |
43 |
| private static final Evaluator AND_EVALUATOR = new AndEvaluator(); |
44 |
| |
45 |
12
| public Node parse(String input)
|
46 |
| { |
47 |
12
| Defense.notNull(input, "input");
|
48 |
| |
49 |
12
| try
|
50 |
| { |
51 |
12
| _input = input;
|
52 |
12
| _lexer = new Lexer(input);
|
53 |
| |
54 |
12
| Node result = expression();
|
55 |
| |
56 |
8
| Token token = next();
|
57 |
| |
58 |
8
| if (token != null)
|
59 |
1
| throw new RuntimeException(ConditionalMessages.unparsedToken(token, _input));
|
60 |
| |
61 |
7
| return result;
|
62 |
| } |
63 |
| finally |
64 |
| { |
65 |
12
| _input = null;
|
66 |
12
| _nextToken = null;
|
67 |
12
| _lexer = null;
|
68 |
12
| _onDeck = false;
|
69 |
| } |
70 |
| } |
71 |
| |
72 |
44
| private Token next()
|
73 |
| { |
74 |
44
| Token result = _onDeck ? _nextToken : _lexer.next();
|
75 |
| |
76 |
44
| _onDeck = false;
|
77 |
44
| _nextToken = null;
|
78 |
| |
79 |
44
| return result;
|
80 |
| } |
81 |
| |
82 |
17
| private Token match(TokenType expected)
|
83 |
| { |
84 |
17
| Token actual = next();
|
85 |
| |
86 |
17
| if (actual == null)
|
87 |
1
| throw new RuntimeException(ConditionalMessages.unexpectedEndOfInput(_input));
|
88 |
| |
89 |
16
| if (actual.getType() != expected)
|
90 |
1
| throw new RuntimeException(ConditionalMessages.unexpectedToken(expected, actual
|
91 |
| .getType(), _input)); |
92 |
| |
93 |
15
| return actual;
|
94 |
| } |
95 |
| |
96 |
79
| private Token peek()
|
97 |
| { |
98 |
79
| if (! _onDeck)
|
99 |
| { |
100 |
30
| _nextToken = _lexer.next();
|
101 |
30
| _onDeck = true;
|
102 |
| } |
103 |
| |
104 |
79
| return _nextToken;
|
105 |
| } |
106 |
| |
107 |
79
| private TokenType peekType()
|
108 |
| { |
109 |
79
| Token next = peek();
|
110 |
| |
111 |
79
| return next == null ? null : next.getType();
|
112 |
| } |
113 |
| |
114 |
79
| private boolean isPeek(TokenType type)
|
115 |
| { |
116 |
79
| return peekType() == type;
|
117 |
| } |
118 |
| |
119 |
17
| private Node expression()
|
120 |
| { |
121 |
17
| Node lnode = term();
|
122 |
| |
123 |
13
| if (isPeek(TokenType.OR))
|
124 |
| { |
125 |
1
| next();
|
126 |
| |
127 |
1
| Node rnode = expression();
|
128 |
| |
129 |
1
| return new NodeImpl(lnode, rnode, OR_EVALUATOR);
|
130 |
| } |
131 |
| |
132 |
12
| if (isPeek(TokenType.AND))
|
133 |
| { |
134 |
1
| next();
|
135 |
| |
136 |
1
| Node rnode = expression();
|
137 |
| |
138 |
1
| return new NodeImpl(lnode, rnode, AND_EVALUATOR);
|
139 |
| } |
140 |
| |
141 |
11
| return lnode;
|
142 |
| } |
143 |
| |
144 |
17
| private Node term()
|
145 |
| { |
146 |
17
| if (isPeek(TokenType.OPAREN))
|
147 |
| { |
148 |
1
| next();
|
149 |
| |
150 |
1
| Node result = expression();
|
151 |
| |
152 |
1
| match(TokenType.CPAREN);
|
153 |
| |
154 |
1
| return result;
|
155 |
| } |
156 |
| |
157 |
16
| if (isPeek(TokenType.NOT))
|
158 |
| { |
159 |
3
| next();
|
160 |
| |
161 |
3
| match(TokenType.OPAREN);
|
162 |
| |
163 |
2
| Node expression = expression();
|
164 |
| |
165 |
2
| match(TokenType.CPAREN);
|
166 |
| |
167 |
1
| return new NodeImpl(expression, null, NOT_EVALUATOR);
|
168 |
| } |
169 |
| |
170 |
13
| if (isPeek(TokenType.PROPERTY))
|
171 |
| { |
172 |
5
| next();
|
173 |
| |
174 |
5
| Token symbolToken = match(TokenType.SYMBOL);
|
175 |
| |
176 |
5
| Evaluator ev = new PropertyEvaluator(symbolToken.getValue());
|
177 |
| |
178 |
5
| return new NodeImpl(ev);
|
179 |
| } |
180 |
| |
181 |
8
| if (isPeek(TokenType.CLASS))
|
182 |
| { |
183 |
6
| next();
|
184 |
| |
185 |
6
| Token symbolToken = match(TokenType.SYMBOL);
|
186 |
| |
187 |
6
| Evaluator ev = new ClassNameEvaluator(symbolToken.getValue());
|
188 |
| |
189 |
6
| return new NodeImpl(ev);
|
190 |
| } |
191 |
| |
192 |
2
| throw new RuntimeException(ConditionalMessages.unparsedToken(next(), _input));
|
193 |
| } |
194 |
| } |