MethodInfo.java
/*
* Javassist, a Java-bytecode translator toolkit.
* Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. Alternatively, the contents of this file may be used under
* the terms of the GNU Lesser General Public License Version 2.1 or later,
* or the Apache License Version 2.0.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*/
package javassist.bytecode;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javassist.ClassPool;
import javassist.bytecode.stackmap.MapMaker;
/**
* <code>method_info</code> structure.
*
* <p>The bytecode sequence of the method is represented
* by a <code>CodeAttribute</code> object.
*
* <p>The following code adds the default constructor to a class:
* of <code>int</code> type:
* <blockquote><pre>
* ClassFile cf = ...
* Bytecode code = new Bytecode(cf.getConstPool());
* code.addAload(0);
* code.addInvokespecial("java/lang/Object", MethodInfo.nameInit, "()V");
* code.addReturn(null);
* code.setMaxLocals(1);
*
* MethodInfo minfo = new MethodInfo(cf.getConstPool(), MethodInfo.nameInit, "()V");
* minfo.setCodeAttribute(code.toCodeAttribute());
* cf.addMethod(minfo);
* </pre></blockquote>
*
* @see #getCodeAttribute()
* @see CodeAttribute
* @see Bytecode
* @see javassist.CtMethod#getMethodInfo()
* @see javassist.CtConstructor#getMethodInfo()
*/
public class MethodInfo {
ConstPool constPool;
int accessFlags;
int name;
String cachedName;
int descriptor;
List<AttributeInfo> attribute; // may be null
/**
* If this value is true, Javassist maintains a <code>StackMap</code> attribute
* generated by the <code>preverify</code> tool of J2ME (CLDC). The initial
* value of this field is <code>false</code>.
*/
public static boolean doPreverify = false;
/**
* The name of constructors: <code><init></code>.
*/
public static final String nameInit = "<init>";
/**
* The name of class initializer (static initializer):
* <code><clinit></code>.
*/
public static final String nameClinit = "<clinit>";
private MethodInfo(ConstPool cp) {
constPool = cp;
attribute = null;
}
/**
* Constructs a <code>method_info</code> structure. The initial value of
* <code>access_flags</code> is zero.
*
* @param cp
* a constant pool table
* @param methodname
* method name
* @param desc
* method descriptor
* @see Descriptor
*/
public MethodInfo(ConstPool cp, String methodname, String desc) {
this(cp);
accessFlags = 0;
name = cp.addUtf8Info(methodname);
cachedName = methodname;
descriptor = constPool.addUtf8Info(desc);
}
MethodInfo(ConstPool cp, DataInputStream in) throws IOException {
this(cp);
read(in);
}
/**
* Constructs a copy of <code>method_info</code> structure. Class names
* appearing in the source <code>method_info</code> are renamed according
* to <code>classnameMap</code>.
*
* <p>
* Note: only <code>Code</code> and <code>Exceptions</code> attributes
* are copied from the source. The other attributes are ignored.
*
* @param cp
* a constant pool table
* @param methodname
* a method name
* @param src
* a source <code>method_info</code>
* @param classnameMap
* specifies pairs of replaced and substituted name.
* @see Descriptor
*/
public MethodInfo(ConstPool cp, String methodname, MethodInfo src,
Map<String,String> classnameMap) throws BadBytecode
{
this(cp);
read(src, methodname, classnameMap);
}
/**
* Returns a string representation of the object.
*/
@Override
public String toString() {
return getName() + " " + getDescriptor();
}
/**
* Copies all constant pool items to a given new constant pool
* and replaces the original items with the new ones.
* This is used for garbage collecting the items of removed fields
* and methods.
*
* @param cp the destination
*/
void compact(ConstPool cp) {
name = cp.addUtf8Info(getName());
descriptor = cp.addUtf8Info(getDescriptor());
attribute = AttributeInfo.copyAll(attribute, cp);
constPool = cp;
}
void prune(ConstPool cp) {
List<AttributeInfo> newAttributes = new ArrayList<AttributeInfo>();
AttributeInfo invisibleAnnotations
= getAttribute(AnnotationsAttribute.invisibleTag);
if (invisibleAnnotations != null) {
invisibleAnnotations = invisibleAnnotations.copy(cp, null);
newAttributes.add(invisibleAnnotations);
}
AttributeInfo visibleAnnotations
= getAttribute(AnnotationsAttribute.visibleTag);
if (visibleAnnotations != null) {
visibleAnnotations = visibleAnnotations.copy(cp, null);
newAttributes.add(visibleAnnotations);
}
AttributeInfo parameterInvisibleAnnotations
= getAttribute(ParameterAnnotationsAttribute.invisibleTag);
if (parameterInvisibleAnnotations != null) {
parameterInvisibleAnnotations = parameterInvisibleAnnotations.copy(cp, null);
newAttributes.add(parameterInvisibleAnnotations);
}
AttributeInfo parameterVisibleAnnotations
= getAttribute(ParameterAnnotationsAttribute.visibleTag);
if (parameterVisibleAnnotations != null) {
parameterVisibleAnnotations = parameterVisibleAnnotations.copy(cp, null);
newAttributes.add(parameterVisibleAnnotations);
}
AnnotationDefaultAttribute defaultAttribute
= (AnnotationDefaultAttribute) getAttribute(AnnotationDefaultAttribute.tag);
if (defaultAttribute != null)
newAttributes.add(defaultAttribute);
ExceptionsAttribute ea = getExceptionsAttribute();
if (ea != null)
newAttributes.add(ea);
AttributeInfo signature
= getAttribute(SignatureAttribute.tag);
if (signature != null) {
signature = signature.copy(cp, null);
newAttributes.add(signature);
}
attribute = newAttributes;
name = cp.addUtf8Info(getName());
descriptor = cp.addUtf8Info(getDescriptor());
constPool = cp;
}
/**
* Returns a method name.
*/
public String getName() {
if (cachedName == null)
cachedName = constPool.getUtf8Info(name);
return cachedName;
}
/**
* Sets a method name.
*/
public void setName(String newName) {
name = constPool.addUtf8Info(newName);
cachedName = newName;
}
/**
* Returns true if this is not a constructor or a class initializer (static
* initializer).
*/
public boolean isMethod() {
String n = getName();
return !n.equals(nameInit) && !n.equals(nameClinit);
}
/**
* Returns a constant pool table used by this method.
*/
public ConstPool getConstPool() {
return constPool;
}
/**
* Returns true if this is a constructor.
*/
public boolean isConstructor() {
return getName().equals(nameInit);
}
/**
* Returns true if this is a class initializer (static initializer).
*/
public boolean isStaticInitializer() {
return getName().equals(nameClinit);
}
/**
* Returns access flags.
*
* @see AccessFlag
*/
public int getAccessFlags() {
return accessFlags;
}
/**
* Sets access flags.
*
* @see AccessFlag
*/
public void setAccessFlags(int acc) {
accessFlags = acc;
}
/**
* Returns a method descriptor.
*
* @see Descriptor
*/
public String getDescriptor() {
return constPool.getUtf8Info(descriptor);
}
/**
* Sets a method descriptor.
*
* @see Descriptor
*/
public void setDescriptor(String desc) {
if (!desc.equals(getDescriptor()))
descriptor = constPool.addUtf8Info(desc);
}
/**
* Returns all the attributes. The returned <code>List</code> object
* is shared with this object. If you add a new attribute to the list,
* the attribute is also added to the method represented by this
* object. If you remove an attribute from the list, it is also removed
* from the method.
*
* @return a list of <code>AttributeInfo</code> objects.
* @see AttributeInfo
*/
public List<AttributeInfo> getAttributes() {
if (attribute == null)
attribute = new ArrayList<AttributeInfo>();
return attribute;
}
/**
* Returns the attribute with the specified name. If it is not found, this
* method returns null.
*
* <p>An attribute name can be obtained by, for example,
* {@link AnnotationsAttribute#visibleTag} or
* {@link AnnotationsAttribute#invisibleTag}.
* </p>
*
* @param name attribute name
* @return an <code>AttributeInfo</code> object or null.
* @see #getAttributes()
*/
public AttributeInfo getAttribute(String name) {
return AttributeInfo.lookup(attribute, name);
}
/**
* Removes an attribute with the specified name.
*
* @param name attribute name.
* @return the removed attribute or null.
* @since 3.21
*/
public AttributeInfo removeAttribute(String name) {
return AttributeInfo.remove(attribute, name);
}
/**
* Appends an attribute. If there is already an attribute with the same
* name, the new one substitutes for it.
*
* @see #getAttributes()
*/
public void addAttribute(AttributeInfo info) {
if (attribute == null)
attribute = new ArrayList<AttributeInfo>();
AttributeInfo.remove(attribute, info.getName());
attribute.add(info);
}
/**
* Returns an Exceptions attribute.
*
* @return an Exceptions attribute or null if it is not specified.
*/
public ExceptionsAttribute getExceptionsAttribute() {
AttributeInfo info = AttributeInfo.lookup(attribute,
ExceptionsAttribute.tag);
return (ExceptionsAttribute)info;
}
/**
* Returns a Code attribute.
*
* @return a Code attribute or null if it is not specified.
*/
public CodeAttribute getCodeAttribute() {
AttributeInfo info = AttributeInfo.lookup(attribute, CodeAttribute.tag);
return (CodeAttribute)info;
}
/**
* Removes an Exception attribute.
*/
public void removeExceptionsAttribute() {
AttributeInfo.remove(attribute, ExceptionsAttribute.tag);
}
/**
* Adds an Exception attribute.
*
* <p>
* The added attribute must share the same constant pool table as this
* <code>method_info</code> structure.
*/
public void setExceptionsAttribute(ExceptionsAttribute cattr) {
removeExceptionsAttribute();
if (attribute == null)
attribute = new ArrayList<AttributeInfo>();
attribute.add(cattr);
}
/**
* Removes a Code attribute.
*/
public void removeCodeAttribute() {
AttributeInfo.remove(attribute, CodeAttribute.tag);
}
/**
* Adds a Code attribute.
*
* <p>
* The added attribute must share the same constant pool table as this
* <code>method_info</code> structure.
*/
public void setCodeAttribute(CodeAttribute cattr) {
removeCodeAttribute();
if (attribute == null)
attribute = new ArrayList<AttributeInfo>();
attribute.add(cattr);
}
/**
* Rebuilds a stack map table if the class file is for Java 6
* or later. Java 5 or older Java VMs do not recognize a stack
* map table. If <code>doPreverify</code> is true, this method
* also rebuilds a stack map for J2ME (CLDC).
*
* @param pool used for making type hierarchy.
* @param cf rebuild if this class file is for Java 6 or later.
* @see #rebuildStackMap(ClassPool)
* @see #rebuildStackMapForME(ClassPool)
* @see #doPreverify
* @since 3.6
*/
public void rebuildStackMapIf6(ClassPool pool, ClassFile cf)
throws BadBytecode
{
if (cf.getMajorVersion() >= ClassFile.JAVA_6)
rebuildStackMap(pool);
if (doPreverify)
rebuildStackMapForME(pool);
}
/**
* Rebuilds a stack map table. If no stack map table is included,
* a new one is created. If this <code>MethodInfo</code> does not
* include a code attribute, nothing happens.
*
* @param pool used for making type hierarchy.
* @see StackMapTable
* @since 3.6
*/
public void rebuildStackMap(ClassPool pool) throws BadBytecode {
CodeAttribute ca = getCodeAttribute();
if (ca != null) {
StackMapTable smt = MapMaker.make(pool, this);
ca.setAttribute(smt);
}
}
/**
* Rebuilds a stack map table for J2ME (CLDC). If no stack map table is included,
* a new one is created. If this <code>MethodInfo</code> does not
* include a code attribute, nothing happens.
*
* @param pool used for making type hierarchy.
* @see StackMap
* @since 3.12
*/
public void rebuildStackMapForME(ClassPool pool) throws BadBytecode {
CodeAttribute ca = getCodeAttribute();
if (ca != null) {
StackMap sm = MapMaker.make2(pool, this);
ca.setAttribute(sm);
}
}
/**
* Returns the line number of the source line corresponding to the specified
* bytecode contained in this method.
*
* @param pos
* the position of the bytecode (>= 0). an index into the code
* array.
* @return -1 if this information is not available.
*/
public int getLineNumber(int pos) {
CodeAttribute ca = getCodeAttribute();
if (ca == null)
return -1;
LineNumberAttribute ainfo = (LineNumberAttribute)ca
.getAttribute(LineNumberAttribute.tag);
if (ainfo == null)
return -1;
return ainfo.toLineNumber(pos);
}
/**
* Changes a super constructor called by this constructor.
*
* <p>
* This method modifies a call to <code>super()</code>, which should be
* at the head of a constructor body, so that a constructor in a different
* super class is called. This method does not change actual parameters.
* Hence the new super class must have a constructor with the same signature
* as the original one.
*
* <p>
* This method should be called when the super class of the class declaring
* this method is changed.
*
* <p>
* This method does not perform anything unless this <code>MethodInfo</code>
* represents a constructor.
*
* @param superclass
* the new super class
*/
public void setSuperclass(String superclass) throws BadBytecode {
if (!isConstructor())
return;
CodeAttribute ca = getCodeAttribute();
byte[] code = ca.getCode();
CodeIterator iterator = ca.iterator();
int pos = iterator.skipSuperConstructor();
if (pos >= 0) { // not this()
ConstPool cp = constPool;
int mref = ByteArray.readU16bit(code, pos + 1);
int nt = cp.getMethodrefNameAndType(mref);
int sc = cp.addClassInfo(superclass);
int mref2 = cp.addMethodrefInfo(sc, nt);
ByteArray.write16bit(mref2, code, pos + 1);
}
}
private void read(MethodInfo src, String methodname, Map<String,String> classnames) {
ConstPool destCp = constPool;
accessFlags = src.accessFlags;
name = destCp.addUtf8Info(methodname);
cachedName = methodname;
ConstPool srcCp = src.constPool;
String desc = srcCp.getUtf8Info(src.descriptor);
String desc2 = Descriptor.rename(desc, classnames);
descriptor = destCp.addUtf8Info(desc2);
attribute = new ArrayList<AttributeInfo>();
ExceptionsAttribute eattr = src.getExceptionsAttribute();
if (eattr != null)
attribute.add(eattr.copy(destCp, classnames));
CodeAttribute cattr = src.getCodeAttribute();
if (cattr != null)
attribute.add(cattr.copy(destCp, classnames));
}
private void read(DataInputStream in) throws IOException {
accessFlags = in.readUnsignedShort();
name = in.readUnsignedShort();
descriptor = in.readUnsignedShort();
int n = in.readUnsignedShort();
attribute = new ArrayList<AttributeInfo>();
for (int i = 0; i < n; ++i)
attribute.add(AttributeInfo.read(constPool, in));
}
void write(DataOutputStream out) throws IOException {
out.writeShort(accessFlags);
out.writeShort(name);
out.writeShort(descriptor);
if (attribute == null)
out.writeShort(0);
else {
out.writeShort(attribute.size());
AttributeInfo.writeAll(attribute, out);
}
}
}