Source Code Cross Referenced for StackMapAttribute.java in  » Rule-Engine » drolls-Rule-Engine » org » drools » asm » attrs » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Rule Engine » drolls Rule Engine » org.drools.asm.attrs 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /**
002:         * ASM: a very small and fast Java bytecode manipulation framework
003:         * Copyright (c) 2000-2005 INRIA, France Telecom
004:         * All rights reserved.
005:         *
006:         * Redistribution and use in source and binary forms, with or without
007:         * modification, are permitted provided that the following conditions
008:         * are met:
009:         * 1. Redistributions of source code must retain the above copyright
010:         *    notice, this list of conditions and the following disclaimer.
011:         * 2. Redistributions in binary form must reproduce the above copyright
012:         *    notice, this list of conditions and the following disclaimer in the
013:         *    documentation and/or other materials provided with the distribution.
014:         * 3. Neither the name of the copyright holders nor the names of its
015:         *    contributors may be used to endorse or promote products derived from
016:         *    this software without specific prior written permission.
017:         *
018:         * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
019:         * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
020:         * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
021:         * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
022:         * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
023:         * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
024:         * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
025:         * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
026:         * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
027:         * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
028:         * THE POSSIBILITY OF SUCH DAMAGE.
029:         */package org.drools.asm.attrs;
030:
031:        import java.util.ArrayList;
032:        import java.util.HashSet;
033:        import java.util.Iterator;
034:        import java.util.List;
035:        import java.util.Set;
036:
037:        import org.drools.asm.Attribute;
038:        import org.drools.asm.ByteVector;
039:        import org.drools.asm.ClassReader;
040:        import org.drools.asm.ClassWriter;
041:        import org.drools.asm.Label;
042:
043:        /**
044:         * StackMapAttribute is used by CDLC preverifier. Definition is given in
045:         * appendix "CLDC Byte Code Typechecker Specification" from CDLC 1.1
046:         * specification. <p> <i>Note that this implementation does not calculate
047:         * StackMapFrame structures from the method bytecode. If method code is changed
048:         * or generated from scratch, then developer is responsible to prepare a correct
049:         * StackMapFrame structures.</i> <p> The format of the stack map in the class
050:         * file is given below. In the following, <ul> <li>if the length of the
051:         * method's byte code1 is 65535 or less, then <tt>uoffset</tt> represents the
052:         * type u2; otherwise <tt>uoffset</tt> represents the type u4.</li> <li>If
053:         * the maximum number of local variables for the method is 65535 or less, then
054:         * <tt>ulocalvar</tt> represents the type u2; otherwise <tt>ulocalvar</tt>
055:         * represents the type u4.</li> <li>If the maximum size of the operand stack
056:         * is 65535 or less, then <tt>ustack</tt> represents the type u2; otherwise
057:         * ustack represents the type u4.</li> </ul>
058:         * 
059:         * <pre>
060:         * stack_map { // attribute StackMap
061:         *   u2 attribute_name_index;
062:         *   u4 attribute_length
063:         *   uoffset number_of_entries;
064:         *   stack_map_frame entries[number_of_entries];
065:         * }
066:         * </pre>
067:         * 
068:         * Each stack map frame has the following format:
069:         * 
070:         * <pre>
071:         * stack_map_frame {
072:         *   uoffset offset;
073:         *   ulocalvar number_of_locals;
074:         *   verification_type_info locals[number_of_locals];
075:         *   ustack number_of_stack_items;
076:         *   verification_type_info stack[number_of_stack_items];
077:         * }
078:         * </pre>
079:         * 
080:         * The <tt>verification_type_info</tt> structure consists of a one-byte tag
081:         * followed by zero or more bytes, giving more information about the tag. Each
082:         * <tt>verification_type_info</tt> structure specifies the verification type
083:         * of one or two locations.
084:         * 
085:         * <pre>
086:         * union verification_type_info {
087:         *   Top_variable_info;
088:         *   Integer_variable_info;
089:         *   Float_variable_info;
090:         *   Long_variable_info;
091:         *   Double_variable_info;
092:         *   Null_variable_info;
093:         *   UninitializedThis_variable_info;
094:         *   Object_variable_info;
095:         *   Uninitialized_variable_info;
096:         * }
097:         *      
098:         * Top_variable_info {
099:         *   u1 tag = ITEM_Top; // 0
100:         * }
101:         *      
102:         * Integer_variable_info {
103:         *   u1 tag = ITEM_Integer; // 1
104:         * }
105:         *      
106:         * Float_variable_info {
107:         *   u1 tag = ITEM_Float; // 2
108:         * }
109:         *      
110:         * Long_variable_info {
111:         *   u1 tag = ITEM_Long; // 4
112:         * }
113:         *      
114:         * Double_variable_info {
115:         *   u1 tag = ITEM_Double; // 3
116:         * }
117:         *      
118:         * Null_variable_info {
119:         *  u1 tag = ITEM_Null; // 5
120:         * }
121:         *      
122:         * UninitializedThis_variable_info {
123:         *   u1 tag = ITEM_UninitializedThis; // 6
124:         * }
125:         *      
126:         * Object_variable_info {
127:         *   u1 tag = ITEM_Object; // 7
128:         *   u2 cpool_index;
129:         * }
130:         *      
131:         * Uninitialized_variable_info {
132:         *   u1 tag = ITEM_Uninitialized // 8
133:         *   uoffset offset;
134:         * }
135:         * </pre>
136:         * 
137:         * @see <a href="http://www.jcp.org/en/jsr/detail?id=139">JSR 139 : Connected
138:         *      Limited Device Configuration 1.1</a>
139:         * 
140:         * @author Eugene Kuleshov
141:         */
142:        public class StackMapAttribute extends Attribute {
143:
144:            static final int MAX_SIZE = 65535;
145:
146:            /**
147:             * A List of <code>StackMapFrame</code> instances.
148:             */
149:            public List frames = new ArrayList();
150:
151:            public StackMapAttribute() {
152:                super ("StackMap");
153:            }
154:
155:            public StackMapAttribute(final List frames) {
156:                this ();
157:                this .frames = frames;
158:            }
159:
160:            public List getFrames() {
161:                return this .frames;
162:            }
163:
164:            public StackMapFrame getFrame(final Label label) {
165:                for (int i = 0; i < this .frames.size(); i++) {
166:                    final StackMapFrame frame = (StackMapFrame) this .frames
167:                            .get(i);
168:                    if (frame.label == label) {
169:                        return frame;
170:                    }
171:                }
172:                return null;
173:            }
174:
175:            public boolean isUnknown() {
176:                return false;
177:            }
178:
179:            public boolean isCodeAttribute() {
180:                return true;
181:            }
182:
183:            protected Attribute read(final ClassReader cr, int off,
184:                    final int len, final char[] buf, final int codeOff,
185:                    final Label[] labels) {
186:                final StackMapAttribute attr = new StackMapAttribute();
187:                // note that this is not the size of Code attribute
188:                final boolean isExtCodeSize = cr.readInt(codeOff + 4) > StackMapAttribute.MAX_SIZE;
189:                final boolean isExtLocals = cr.readUnsignedShort(codeOff + 2) > StackMapAttribute.MAX_SIZE;
190:                final boolean isExtStack = cr.readUnsignedShort(codeOff) > StackMapAttribute.MAX_SIZE;
191:
192:                int size = 0;
193:                if (isExtCodeSize) {
194:                    size = cr.readInt(off);
195:                    off += 4;
196:                } else {
197:                    size = cr.readUnsignedShort(off);
198:                    off += 2;
199:                }
200:                for (int i = 0; i < size; i++) {
201:                    int offset;
202:                    if (isExtCodeSize) {
203:                        offset = cr.readInt(off);
204:                        off += 4;
205:                    } else {
206:                        offset = cr.readUnsignedShort(off);
207:                        off += 2;
208:                    }
209:
210:                    final Label label = getLabel(offset, labels);
211:                    final List locals = new ArrayList();
212:                    final List stack = new ArrayList();
213:
214:                    off = readTypeInfo(cr, off, locals, labels, buf,
215:                            isExtLocals, isExtCodeSize);
216:                    off = readTypeInfo(cr, off, stack, labels, buf, isExtStack,
217:                            isExtCodeSize);
218:
219:                    attr.frames.add(new StackMapFrame(label, locals, stack));
220:                }
221:                return attr;
222:            }
223:
224:            private int readTypeInfo(final ClassReader cr, int off,
225:                    final List info, final Label[] labels, final char[] buf,
226:                    final boolean isExt, final boolean isExtCode) {
227:                int n = 0;
228:                if (isExt) {
229:                    n = cr.readInt(off);
230:                    off += 4;
231:                } else {
232:                    n = cr.readUnsignedShort(off);
233:                    off += 2;
234:                }
235:                for (int j = 0; j < n; j++) {
236:                    final int itemType = cr.readByte(off++);
237:                    final StackMapType typeInfo = StackMapType
238:                            .getTypeInfo(itemType);
239:                    info.add(typeInfo);
240:                    switch (itemType) {
241:                    case StackMapType.ITEM_Object: //
242:                        typeInfo.setObject(cr.readClass(off, buf));
243:                        off += 2;
244:                        break;
245:                    case StackMapType.ITEM_Uninitialized: //
246:                        int offset;
247:                        if (isExtCode) {
248:                            offset = cr.readInt(off);
249:                            off += 4;
250:                        } else {
251:                            offset = cr.readUnsignedShort(off);
252:                            off += 2;
253:                        }
254:                        typeInfo.setLabel(getLabel(offset, labels));
255:                        break;
256:                    }
257:                }
258:                return off;
259:            }
260:
261:            private void writeTypeInfo(final ByteVector bv,
262:                    final ClassWriter cw, final List info, final int max) {
263:                if (max > StackMapAttribute.MAX_SIZE) {
264:                    bv.putInt(info.size());
265:                } else {
266:                    bv.putShort(info.size());
267:                }
268:                for (int j = 0; j < info.size(); j++) {
269:                    final StackMapType typeInfo = (StackMapType) info.get(j);
270:                    bv.putByte(typeInfo.getType());
271:                    switch (typeInfo.getType()) {
272:                    case StackMapType.ITEM_Object: //
273:                        bv.putShort(cw.newClass(typeInfo.getObject()));
274:                        break;
275:
276:                    case StackMapType.ITEM_Uninitialized: //
277:                        bv.putShort(typeInfo.getLabel().getOffset());
278:                        break;
279:
280:                    }
281:                }
282:            }
283:
284:            private Label getLabel(final int offset, final Label[] labels) {
285:                final Label l = labels[offset];
286:                if (l != null) {
287:                    return l;
288:                }
289:                return labels[offset] = new Label();
290:            }
291:
292:            protected ByteVector write(final ClassWriter cw, final byte[] code,
293:                    final int len, final int maxStack, final int maxLocals) {
294:                final ByteVector bv = new ByteVector();
295:                if (code != null && code.length > StackMapAttribute.MAX_SIZE) { // TODO verify value
296:                    bv.putInt(this .frames.size());
297:                } else {
298:                    bv.putShort(this .frames.size());
299:                }
300:                for (int i = 0; i < this .frames.size(); i++) {
301:                    writeFrame((StackMapFrame) this .frames.get(i), cw,
302:                            maxStack, maxLocals, bv);
303:                }
304:                return bv;
305:            }
306:
307:            protected Label[] getLabels() {
308:                final HashSet labels = new HashSet();
309:                for (int i = 0; i < this .frames.size(); i++) {
310:                    getFrameLabels((StackMapFrame) this .frames.get(i), labels);
311:                }
312:                return (Label[]) labels.toArray(new Label[labels.size()]);
313:            }
314:
315:            private void writeFrame(final StackMapFrame frame,
316:                    final ClassWriter cw, final int maxStack,
317:                    final int maxLocals, final ByteVector bv) {
318:                bv.putShort(frame.label.getOffset());
319:                writeTypeInfo(bv, cw, frame.locals, maxLocals);
320:                writeTypeInfo(bv, cw, frame.stack, maxStack);
321:            }
322:
323:            private void getFrameLabels(final StackMapFrame frame,
324:                    final Set labels) {
325:                labels.add(frame.label);
326:                getTypeInfoLabels(labels, frame.locals);
327:                getTypeInfoLabels(labels, frame.stack);
328:            }
329:
330:            private void getTypeInfoLabels(final Set labels, final List info) {
331:                for (final Iterator it = info.iterator(); it.hasNext();) {
332:                    final StackMapType typeInfo = (StackMapType) it.next();
333:                    if (typeInfo.getType() == StackMapType.ITEM_Uninitialized) {
334:                        labels.add(typeInfo.getLabel());
335:                    }
336:                }
337:            }
338:
339:            public String toString() {
340:                final StringBuffer sb = new StringBuffer("StackMap[");
341:                for (int i = 0; i < this .frames.size(); i++) {
342:                    sb.append('\n').append('[').append(this .frames.get(i))
343:                            .append(']');
344:                }
345:                sb.append("\n]");
346:                return sb.toString();
347:            }
348:        }
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