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1
15 package org.apache.hivemind.lib.chain;
16
17 import java.lang.reflect.Modifier  ;
18 import java.util.HashMap ;
19 import java.util.List ;
20 import java.util.Map ;
21
22 import org.apache.hivemind.ClassResolver;
23 import org.apache.hivemind.service.BodyBuilder;
24 import org.apache.hivemind.service.ClassFab;
25 import org.apache.hivemind.service.ClassFabUtils;
26 import org.apache.hivemind.service.ClassFactory;
27 import org.apache.hivemind.service.MethodIterator;
28 import org.apache.hivemind.service.MethodSignature;
29 import org.apache.hivemind.util.ConstructorUtils;
30 import org.apache.hivemind.util.Defense;
31
32
38 public class ChainBuilderImpl implements ChainBuilder
39 {
40 private ClassResolver _classResolver;
41
42 private ClassFactory _classFactory;
43
44
47
48 private Map _implementations = new HashMap ();
49
50 public Object buildImplementation(Class commandInterface, List commands, String toString)
51 {
52 Defense.notNull(commandInterface, "commandInterface");
53 Defense.notNull(commands, "commands");
54 Defense.notNull(toString, "toString");
55
56 Class instanceClass = findImplementationClass(commandInterface);
57
58 return createInstance(instanceClass, commands, toString);
59 }
60
61 private synchronized Class findImplementationClass(Class commandInterface)
62 {
63 Class result = (Class ) _implementations.get(commandInterface);
64
65 if (result == null)
66 {
67 result = constructImplementationClass(commandInterface);
68
69 _implementations.put(commandInterface, result);
70 }
71
72 return result;
73 }
74
75 private Class constructImplementationClass(Class commandInterface)
76 {
77 String name = ClassFabUtils.generateClassName(commandInterface);
78
79 ClassFab cf = _classFactory.newClass(name, Object .class);
80
81 addInfrastructure(cf, commandInterface);
82
83 addMethods(cf, commandInterface);
84
85 return cf.createClass();
86 }
87
88 void addInfrastructure(ClassFab cf, Class commandInterface)
89 {
90 Class array = _classResolver.findClass(commandInterface.getName() + "[]");
91
92 cf.addInterface(commandInterface);
93 cf.addField("_commands", array);
94 cf.addField("_toString", String .class);
95
96 BodyBuilder builder = new BodyBuilder();
97
98 builder.begin();
99 builder.addln("_commands = ({0}[]) $1.toArray(new {0}[0]);", commandInterface.getName());
100 builder.addln("_toString = $2;");
101 builder.end();
102
103 cf.addConstructor(new Class []
104 { List .class, String .class }, null, builder.toString());
105 }
106
107 private Object createInstance(Class instanceClass, List commands, String toString)
108 {
109 return ConstructorUtils.invokeConstructor(instanceClass, new Object []
110 { commands, toString });
111 }
112
113 void addMethods(ClassFab cf, Class commandInterface)
114 {
115 MethodIterator mi = new MethodIterator(commandInterface);
116
117 while (mi.hasNext())
118 {
119 MethodSignature sig = mi.next();
120
121 addMethod(cf, commandInterface, sig);
122 }
123
124 if (!mi.getToString())
125 addToString(cf);
126 }
127
128 void addMethod(ClassFab cf, Class commandInterface, MethodSignature sig)
129 {
130 Class returnType = sig.getReturnType();
131
132 if (returnType.equals(void.class))
133 {
134 addVoidMethod(cf, commandInterface, sig);
135 return;
136 }
137
138 String defaultValue = defaultForReturnType(returnType);
139
140 BodyBuilder builder = new BodyBuilder();
141 builder.begin();
142
143 builder
144 .addln(
145 "{0} result = {1};",
146 ClassFabUtils.getJavaClassName(returnType),
147 defaultValue);
148 builder.addln("for (int i = 0; i < _commands.length; i++)");
149
150 builder.begin();
151 builder.addln("result = _commands[i].{0}($$);", sig.getName());
152
153 builder.addln("if (result != {0}) break;", defaultValue);
154
155 builder.end();
156
157 builder.addln("return result;");
158 builder.end();
159
160 cf.addMethod(Modifier.PUBLIC, sig, builder.toString());
161 }
162
163 String defaultForReturnType(Class returnType)
164 {
165
167 if (!returnType.isPrimitive())
168 return "null";
169
170 if (returnType.equals(boolean.class))
171 return "false";
172
173
176 return "0";
177 }
178
179 private void addVoidMethod(ClassFab cf, Class commandInterface, MethodSignature sig)
180 {
181 BodyBuilder builder = new BodyBuilder();
182
183 builder.begin();
184
185 builder.addln("for (int i = 0; i < _commands.length; i++)");
186 builder.addln("_commands[i].{0}($$);", sig.getName());
187
188 builder.end();
189
190 cf.addMethod(Modifier.PUBLIC, sig, builder.toString());
191 }
192
193 void addToString(ClassFab cf)
194 {
195 MethodSignature sig = new MethodSignature(String .class, "toString", null, null);
196
197 cf.addMethod(Modifier.PUBLIC, sig, "return _toString;");
198 }
199
200 public void setClassFactory(ClassFactory classFactory)
201 {
202 _classFactory = classFactory;
203 }
204
205 public void setClassResolver(ClassResolver classResolver)
206 {
207 _classResolver = classResolver;
208 }
209 } |
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