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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package com.sun.jdi;
import java.util.List;
import java.util.Map;
/**
* The state of one method invocation on a thread's call stack.
* As a thread executes, stack frames are pushed and popped from
* its call stack as methods are invoked and then return. A StackFrame
* mirrors one such frame from a target VM at some point in its
* thread's execution. The call stack is, then, simply a List of
* StackFrame objects. The call stack can be obtained any time a thread
* is suspended through a call to {@link ThreadReference#frames}
* <p>
* StackFrames provide access to a method's local variables and their
* current values.
* <p>
* The lifetime of a StackFrame is very limited. It is available only
* for suspended threads and becomes invalid once its thread is resumed.
* <p>
* Any method on <code>StackFrame</code> which
* takes <code>StackFrame</code> as an parameter may throw
* {@link com.sun.jdi.VMDisconnectedException} if the target VM is
* disconnected and the {@link com.sun.jdi.event.VMDisconnectEvent} has been or is
* available to be read from the {@link com.sun.jdi.event.EventQueue}.
* <p>
* Any method on <code>StackFrame</code> which
* takes <code>StackFrame</code> as an parameter may throw
* {@link com.sun.jdi.VMOutOfMemoryException} if the target VM has run out of memory.
*
* @author Robert Field
* @author Gordon Hirsch
* @author James McIlree
* @since 1.3
*/
public interface StackFrame extends Mirror, Locatable
{
/**
* Returns the {@link Location} of the current instruction in the frame.
* The method for which this frame was created can also be accessed
* through the returned location.
* For the top frame in the stack, this location identifies the
* next instruction to be executed. For all other frames, this
* location identifies the instruction that caused the next frame's
* method to be invoked.
* If the frame represents a native method invocation, the returned
* location indicates the class and method, but the code index will
* not be valid (-1).
*
* @return the {@link Location} of the current instruction.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
*/
Location location();
/**
* Returns the thread under which this frame's method is running.
*
* @return a {@link ThreadReference} which mirrors the frame's thread.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
*/
ThreadReference thread();
/**
* Returns the value of 'this' for the current frame.
* The {@link ObjectReference} for 'this' is only available for
* non-native instance methods.
*
* @return an {@link ObjectReference}, or null if the frame represents
* a native or static method.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
*/
ObjectReference thisObject();
/**
* Returns a list containing each {@link LocalVariable}
* that can be accessed from this frame's location.
* <p>
* Visibility is based on the code index of the current instruction of
* this StackFrame. Each variable has a range of byte code indices in which
* it is accessible.
* If this stack frame's method
* matches this variable's method and if the code index of this
* StackFrame is within the variable's byte code range, the variable is
* visible.
* <p>
* A variable's byte code range is at least as large as the scope of
* that variable, but can continue beyond the end of the scope under
* certain circumstances:
* <ul>
* <li>the compiler/VM does not immediately reuse the variable's slot.
* <li>the compiler/VM is implemented to report the extended range that
* would result from the item above.
* </ul>
* The advantage of an extended range is that variables from recently
* exited scopes may remain available for examination (this is especially
* useful for loop indices). If, as a result of the extensions above,
* the current frame location is contained within the range
* of multiple local variables of the same name, the variable with the
* highest-starting range is chosen for the returned list.
*
* @return the list of {@link LocalVariable} objects currently visible;
* the list will be empty if there are no visible variables;
* specifically, frames in native methods will always return a
* zero-length list.
* @throws AbsentInformationException if there is no local variable
* information for this method.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
* @throws NativeMethodException if the current method is native.
*/
List<LocalVariable> visibleVariables() throws AbsentInformationException;
/**
* Finds a {@link LocalVariable} that matches the given name and is
* visible at the current frame location.
* See {@link #visibleVariables} for more information on visibility.
*
* @param name the variable name to find
* @return the matching {@link LocalVariable}, or null if there is no
* visible variable with the given name; frames in native methods
* will always return null.
* @throws AbsentInformationException if there is no local variable
* information for this method.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
* @throws NativeMethodException if the current method is native.
*/
LocalVariable visibleVariableByName(String name) throws AbsentInformationException;
/**
* Gets the {@link Value} of a {@link LocalVariable} in this frame.
* The variable must be valid for this frame's method and visible
* according to the rules described in {@link #visibleVariables}.
*
* @param variable the {@link LocalVariable} to be accessed
* @return the {@link Value} of the instance field.
* @throws java.lang.IllegalArgumentException if the variable is
* either invalid for this frame's method or not visible.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
*/
Value getValue(LocalVariable variable);
/**
* Returns the values of multiple local variables in this frame.
* Each variable must be valid for this frame's method and visible
* according to the rules described in {@link #visibleVariables}.
*
* @param variables a list of {@link LocalVariable} objects to be accessed
* @return a map associating each {@link LocalVariable} with
* its {@link Value}
* @throws java.lang.IllegalArgumentException if any variable is
* either invalid for this frame's method or not visible.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
*/
Map<LocalVariable,Value> getValues(List<? extends LocalVariable> variables);
/**
* Sets the {@link Value} of a {@link LocalVariable} in this frame.
* The variable must be valid for this frame's method and visible
* according to the rules described in {@link #visibleVariables}.
* <p>
* Object values must be assignment compatible with the variable type
* (This implies that the variable type must be loaded through the
* enclosing class's class loader). Primitive values must be
* either assignment compatible with the variable type or must be
* convertible to the variable type without loss of information.
* See JLS section 5.2 for more information on assignment
* compatibility.
*
* @param variable the field containing the requested value
* @param value the new value to assign
* @throws java.lang.IllegalArgumentException if the field is not valid for
* this object's class.
* @throws InvalidTypeException if the value's type does not match
* the variable's type.
* @throws ClassNotLoadedException if the variable type has not yet been loaded
* through the appropriate class loader.
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
* @throws VMCannotBeModifiedException if the VirtualMachine is read-only - see {@link VirtualMachine#canBeModified()}.
*/
void setValue(LocalVariable variable, Value value)
throws InvalidTypeException, ClassNotLoadedException;
/**
* Returns the values of all arguments in this frame. Values are
* returned even if no local variable information is present.
*
* @return a list containing a {@link Value} object for each argument
* to this frame, in the order in which the arguments were
* declared. If the method corresponding to this frame has
* no arguments, an empty list is returned.
*
* @throws InvalidStackFrameException if this stack frame has become
* invalid. Once the frame's thread is resumed, the stack frame is
* no longer valid.
* @since 1.6
*/
List<Value> getArgumentValues();
}