1/* 2 * Copyright (c) 1998, 2013, 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 26package com.sun.jdi; 27 28import java.util.List; 29import java.util.Map; 30 31/** 32 * The state of one method invocation on a thread's call stack. 33 * As a thread executes, stack frames are pushed and popped from 34 * its call stack as methods are invoked and then return. A StackFrame 35 * mirrors one such frame from a target VM at some point in its 36 * thread's execution. The call stack is, then, simply a List of 37 * StackFrame objects. The call stack can be obtained any time a thread 38 * is suspended through a call to {@link ThreadReference#frames} 39 * <p> 40 * StackFrames provide access to a method's local variables and their 41 * current values. 42 * <p> 43 * The lifetime of a StackFrame is very limited. It is available only 44 * for suspended threads and becomes invalid once its thread is resumed. 45 * <p> 46 * Any method on <code>StackFrame</code> which 47 * takes <code>StackFrame</code> as an parameter may throw 48 * {@link com.sun.jdi.VMDisconnectedException} if the target VM is 49 * disconnected and the {@link com.sun.jdi.event.VMDisconnectEvent} has been or is 50 * available to be read from the {@link com.sun.jdi.event.EventQueue}. 51 * <p> 52 * Any method on <code>StackFrame</code> which 53 * takes <code>StackFrame</code> as an parameter may throw 54 * {@link com.sun.jdi.VMOutOfMemoryException} if the target VM has run out of memory. 55 * 56 * @author Robert Field 57 * @author Gordon Hirsch 58 * @author James McIlree 59 * @since 1.3 60 */ 61public interface StackFrame extends Mirror, Locatable { 62 63 /** 64 * Returns the {@link Location} of the current instruction in the frame. 65 * The method for which this frame was created can also be accessed 66 * through the returned location. 67 * For the top frame in the stack, this location identifies the 68 * next instruction to be executed. For all other frames, this 69 * location identifies the instruction that caused the next frame's 70 * method to be invoked. 71 * If the frame represents a native method invocation, the returned 72 * location indicates the class and method, but the code index will 73 * not be valid (-1). 74 * 75 * @return the {@link Location} of the current instruction. 76 * @throws InvalidStackFrameException if this stack frame has become 77 * invalid. Once the frame's thread is resumed, the stack frame is 78 * no longer valid. 79 */ 80 Location location(); 81 82 /** 83 * Returns the thread under which this frame's method is running. 84 * 85 * @return a {@link ThreadReference} which mirrors the frame's thread. 86 * @throws InvalidStackFrameException if this stack frame has become 87 * invalid. Once the frame's thread is resumed, the stack frame is 88 * no longer valid. 89 */ 90 ThreadReference thread(); 91 92 /** 93 * Returns the value of 'this' for the current frame. 94 * The {@link ObjectReference} for 'this' is only available for 95 * non-native instance methods. 96 * 97 * @return an {@link ObjectReference}, or null if the frame represents 98 * a native or static method. 99 * @throws InvalidStackFrameException if this stack frame has become 100 * invalid. Once the frame's thread is resumed, the stack frame is 101 * no longer valid. 102 */ 103 ObjectReference thisObject(); 104 105 /** 106 * Returns a list containing each {@link LocalVariable} 107 * that can be accessed from this frame's location. 108 * <p> 109 * Visibility is based on the code index of the current instruction of 110 * this StackFrame. Each variable has a range of byte code indices in which 111 * it is accessible. 112 * If this stack frame's method 113 * matches this variable's method and if the code index of this 114 * StackFrame is within the variable's byte code range, the variable is 115 * visible. 116 * <p> 117 * A variable's byte code range is at least as large as the scope of 118 * that variable, but can continue beyond the end of the scope under 119 * certain circumstances: 120 * <ul> 121 * <li>the compiler/VM does not immediately reuse the variable's slot. 122 * <li>the compiler/VM is implemented to report the extended range that 123 * would result from the item above. 124 * </ul> 125 * The advantage of an extended range is that variables from recently 126 * exited scopes may remain available for examination (this is especially 127 * useful for loop indices). If, as a result of the extensions above, 128 * the current frame location is contained within the range 129 * of multiple local variables of the same name, the variable with the 130 * highest-starting range is chosen for the returned list. 131 * 132 * @return the list of {@link LocalVariable} objects currently visible; 133 * the list will be empty if there are no visible variables; 134 * specifically, frames in native methods will always return a 135 * zero-length list. 136 * @throws AbsentInformationException if there is no local variable 137 * information for this method. 138 * @throws InvalidStackFrameException if this stack frame has become 139 * invalid. Once the frame's thread is resumed, the stack frame is 140 * no longer valid. 141 * @throws NativeMethodException if the current method is native. 142 */ 143 List<LocalVariable> visibleVariables() throws AbsentInformationException; 144 145 /** 146 * Finds a {@link LocalVariable} that matches the given name and is 147 * visible at the current frame location. 148 * See {@link #visibleVariables} for more information on visibility. 149 * 150 * @param name the variable name to find 151 * @return the matching {@link LocalVariable}, or null if there is no 152 * visible variable with the given name; frames in native methods 153 * will always return null. 154 * @throws AbsentInformationException if there is no local variable 155 * information for this method. 156 * @throws InvalidStackFrameException if this stack frame has become 157 * invalid. Once the frame's thread is resumed, the stack frame is 158 * no longer valid. 159 * @throws NativeMethodException if the current method is native. 160 */ 161 LocalVariable visibleVariableByName(String name) throws AbsentInformationException; 162 163 /** 164 * Gets the {@link Value} of a {@link LocalVariable} in this frame. 165 * The variable must be valid for this frame's method and visible 166 * according to the rules described in {@link #visibleVariables}. 167 * 168 * @param variable the {@link LocalVariable} to be accessed 169 * @return the {@link Value} of the instance field. 170 * @throws java.lang.IllegalArgumentException if the variable is 171 * either invalid for this frame's method or not visible. 172 * @throws InvalidStackFrameException if this stack frame has become 173 * invalid. Once the frame's thread is resumed, the stack frame is 174 * no longer valid. 175 */ 176 Value getValue(LocalVariable variable); 177 178 /** 179 * Returns the values of multiple local variables in this frame. 180 * Each variable must be valid for this frame's method and visible 181 * according to the rules described in {@link #visibleVariables}. 182 * 183 * @param variables a list of {@link LocalVariable} objects to be accessed 184 * @return a map associating each {@link LocalVariable} with 185 * its {@link Value} 186 * @throws java.lang.IllegalArgumentException if any variable is 187 * either invalid for this frame's method or not visible. 188 * @throws InvalidStackFrameException if this stack frame has become 189 * invalid. Once the frame's thread is resumed, the stack frame is 190 * no longer valid. 191 */ 192 Map<LocalVariable,Value> getValues(List<? extends LocalVariable> variables); 193 194 /** 195 * Sets the {@link Value} of a {@link LocalVariable} in this frame. 196 * The variable must be valid for this frame's method and visible 197 * according to the rules described in {@link #visibleVariables}. 198 * <p> 199 * Object values must be assignment compatible with the variable type 200 * (This implies that the variable type must be loaded through the 201 * enclosing class's class loader). Primitive values must be 202 * either assignment compatible with the variable type or must be 203 * convertible to the variable type without loss of information. 204 * See JLS section 5.2 for more information on assignment 205 * compatibility. 206 * 207 * @param variable the field containing the requested value 208 * @param value the new value to assign 209 * @throws java.lang.IllegalArgumentException if the field is not valid for 210 * this object's class. 211 * @throws InvalidTypeException if the value's type does not match 212 * the variable's type. 213 * @throws ClassNotLoadedException if the variable type has not yet been loaded 214 * through the appropriate class loader. 215 * @throws InvalidStackFrameException if this stack frame has become 216 * invalid. Once the frame's thread is resumed, the stack frame is 217 * no longer valid. 218 * @throws VMCannotBeModifiedException if the VirtualMachine is read-only - see {@link VirtualMachine#canBeModified()}. 219 */ 220 void setValue(LocalVariable variable, Value value) 221 throws InvalidTypeException, ClassNotLoadedException; 222 223 /** 224 * Returns the values of all arguments in this frame. Values are 225 * returned even if no local variable information is present. 226 * 227 * @return a list containing a {@link Value} object for each argument 228 * to this frame, in the order in which the arguments were 229 * declared. If the method corresponding to this frame has 230 * no arguments, an empty list is returned. 231 * 232 * @throws InvalidStackFrameException if this stack frame has become 233 * invalid. Once the frame's thread is resumed, the stack frame is 234 * no longer valid. 235 * @since 1.6 236 */ 237 List<Value> getArgumentValues(); 238 239} 240