1 /*
2 * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26
27 /*
28 * The Original Code is HAT. The Initial Developer of the
29 * Original Code is Bill Foote, with contributions from others
30 * at JavaSoft/Sun.
31 */
32
33 package com.sun.tools.hat.internal.oql;
34
35 import com.sun.tools.hat.internal.model.*;
36 import java.io.*;
37 import java.lang.reflect.*;
38 import java.util.*;
39
40 /**
41 * This is Object Query Language Interpreter
42 *
43 */
44 public class OQLEngine {
45 static {
46 try {
47 // Do we have javax.script support?
48 // create ScriptEngineManager
49 Class<?> managerClass = Class.forName("javax.script.ScriptEngineManager");
50 Object manager = managerClass.newInstance();
51
52 // create JavaScript engine
53 Method getEngineMethod = managerClass.getMethod("getEngineByName",
54 new Class<?>[] { String.class });
55 Object jse = getEngineMethod.invoke(manager, new Object[] {"js"});
56 oqlSupported = (jse != null);
57 } catch (Exception exp) {
58 oqlSupported = false;
59 }
60 }
61
62 // check OQL is supported or not before creating OQLEngine
63 public static boolean isOQLSupported() {
64 return oqlSupported;
65 }
66
67 public OQLEngine(Snapshot snapshot) {
68 if (!isOQLSupported()) {
69 throw new UnsupportedOperationException("OQL not supported");
70 }
71 init(snapshot);
72 }
73
74 /**
75 Query is of the form
76
77 select <java script code to select>
78 [ from [instanceof] <class name> [<identifier>]
79 [ where <java script boolean expression> ]
80 ]
81 */
82 public synchronized void executeQuery(String query, ObjectVisitor visitor)
83 throws OQLException {
84 debugPrint("query : " + query);
85 StringTokenizer st = new StringTokenizer(query);
86 if (st.hasMoreTokens()) {
87 String first = st.nextToken();
88 if (! first.equals("select") ) {
89 // Query does not start with 'select' keyword.
90 // Just treat it as plain JavaScript and eval it.
91 try {
92 Object res = evalScript(query);
93 visitor.visit(res);
94 } catch (Exception e) {
95 throw new OQLException(e);
96 }
97 return;
98 }
99 } else {
100 throw new OQLException("query syntax error: no 'select' clause");
101 }
102
103 String selectExpr = "";
104 boolean seenFrom = false;
105 while (st.hasMoreTokens()) {
106 String tok = st.nextToken();
107 if (tok.equals("from")) {
108 seenFrom = true;
109 break;
110 }
111 selectExpr += " " + tok;
112 }
113
114 if (selectExpr.equals("")) {
115 throw new OQLException("query syntax error: 'select' expression can not be empty");
116 }
117
118 String className = null;
119 boolean isInstanceOf = false;
120 String whereExpr = null;
121 String identifier = null;
122
123 if (seenFrom) {
124 if (st.hasMoreTokens()) {
125 String tmp = st.nextToken();
126 if (tmp.equals("instanceof")) {
127 isInstanceOf = true;
128 if (! st.hasMoreTokens()) {
129 throw new OQLException("no class name after 'instanceof'");
130 }
131 className = st.nextToken();
132 } else {
133 className = tmp;
134 }
135 } else {
136 throw new OQLException("query syntax error: class name must follow 'from'");
137 }
138
139 if (st.hasMoreTokens()) {
140 identifier = st.nextToken();
141 if (identifier.equals("where")) {
142 throw new OQLException("query syntax error: identifier should follow class name");
143 }
144 if (st.hasMoreTokens()) {
145 String tmp = st.nextToken();
146 if (! tmp.equals("where")) {
147 throw new OQLException("query syntax error: 'where' clause expected after 'from' clause");
148 }
149
150 whereExpr = "";
151 while (st.hasMoreTokens()) {
152 whereExpr += " " + st.nextToken();
153 }
154 if (whereExpr.equals("")) {
155 throw new OQLException("query syntax error: 'where' clause cannot have empty expression");
156 }
157 }
158 } else {
159 throw new OQLException("query syntax error: identifier should follow class name");
160 }
161 }
162
163 executeQuery(new OQLQuery(selectExpr, isInstanceOf, className,
164 identifier, whereExpr), visitor);
165 }
166
167 private void executeQuery(OQLQuery q, ObjectVisitor visitor)
168 throws OQLException {
169 JavaClass clazz = null;
170 if (q.className != null) {
171 clazz = snapshot.findClass(q.className);
172 if (clazz == null) {
173 throw new OQLException(q.className + " is not found!");
174 }
175 }
176
177 StringBuffer buf = new StringBuffer();
178 buf.append("function __select__(");
179 if (q.identifier != null) {
180 buf.append(q.identifier);
181 }
182 buf.append(") { return ");
183 buf.append(q.selectExpr.replace('\n', ' '));
184 buf.append("; }");
185
186 String selectCode = buf.toString();
187 debugPrint(selectCode);
188 String whereCode = null;
189 if (q.whereExpr != null) {
190 buf = new StringBuffer();
191 buf.append("function __where__(");
192 buf.append(q.identifier);
193 buf.append(") { return ");
194 buf.append(q.whereExpr.replace('\n', ' '));
195 buf.append("; }");
196 whereCode = buf.toString();
197 }
198 debugPrint(whereCode);
199
200 // compile select expression and where condition
201 try {
202 evalMethod.invoke(engine, new Object[] { selectCode });
203 if (whereCode != null) {
204 evalMethod.invoke(engine, new Object[] { whereCode });
205 }
206
207 if (q.className != null) {
208 Enumeration<JavaHeapObject> objects = clazz.getInstances(q.isInstanceOf);
209 while (objects.hasMoreElements()) {
210 JavaHeapObject obj = objects.nextElement();
211 Object[] args = new Object[] { wrapJavaObject(obj) };
212 boolean b = (whereCode == null);
213 if (!b) {
214 Object res = call("__where__", args);
215 if (res instanceof Boolean) {
216 b = ((Boolean)res).booleanValue();
217 } else if (res instanceof Number) {
218 b = ((Number)res).intValue() != 0;
219 } else {
220 b = (res != null);
221 }
222 }
223
224 if (b) {
225 Object select = call("__select__", args);
226 if (visitor.visit(select)) return;
227 }
228 }
229 } else {
230 // simple "select <expr>" query
231 Object select = call("__select__", new Object[] {});
232 visitor.visit(select);
233 }
234 } catch (Exception e) {
235 throw new OQLException(e);
236 }
237 }
238
239 public Object evalScript(String script) throws Exception {
240 return evalMethod.invoke(engine, new Object[] { script });
241 }
242
243 public Object wrapJavaObject(JavaHeapObject obj) throws Exception {
244 return call("wrapJavaObject", new Object[] { obj });
245 }
246
247 public Object toHtml(Object obj) throws Exception {
248 return call("toHtml", new Object[] { obj });
249 }
250
251 public Object call(String func, Object[] args) throws Exception {
252 return invokeMethod.invoke(engine, new Object[] { func, args });
253 }
254
255 private static void debugPrint(String msg) {
256 if (debug) System.out.println(msg);
257 }
258
259 private void init(Snapshot snapshot) throws RuntimeException {
260 this.snapshot = snapshot;
261 try {
262 // create ScriptEngineManager
263 Class<?> managerClass = Class.forName("javax.script.ScriptEngineManager");
264 Object manager = managerClass.newInstance();
265
266 // create JavaScript engine
267 Method getEngineMethod = managerClass.getMethod("getEngineByName",
268 new Class<?>[] { String.class });
269 engine = getEngineMethod.invoke(manager, new Object[] {"js"});
270
271 // initialize engine with init file (hat.js)
272 InputStream strm = getInitStream();
273 Class<?> engineClass = Class.forName("javax.script.ScriptEngine");
274 evalMethod = engineClass.getMethod("eval",
275 new Class<?>[] { Reader.class });
276 evalMethod.invoke(engine, new Object[] {new InputStreamReader(strm)});
277
278 // initialize ScriptEngine.eval(String) and
279 // Invocable.invokeFunction(String, Object[]) methods.
280 Class<?> invocableClass = Class.forName("javax.script.Invocable");
281
282 evalMethod = engineClass.getMethod("eval",
283 new Class<?>[] { String.class });
284 invokeMethod = invocableClass.getMethod("invokeFunction",
285 new Class<?>[] { String.class, Object[].class });
286
287 // initialize ScriptEngine.put(String, Object) method
288 Method putMethod = engineClass.getMethod("put",
289 new Class<?>[] { String.class, Object.class });
290
291 // call ScriptEngine.put to initialize built-in heap object
292 putMethod.invoke(engine, new Object[] {
293 "heap", call("wrapHeapSnapshot", new Object[] { snapshot })
294 });
295 } catch (Exception e) {
296 if (debug) e.printStackTrace();
297 throw new RuntimeException(e);
298 }
299 }
300
301 private InputStream getInitStream() {
302 return getClass().getResourceAsStream("/com/sun/tools/hat/resources/hat.js");
303 }
304
305 private Object engine;
306 private Method evalMethod;
307 private Method invokeMethod;
308 private Snapshot snapshot;
309 private static boolean debug = false;
310 private static boolean oqlSupported;
311 }