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/*
* ProGuardCORE -- library to process Java bytecode.
*
* Copyright (c) 2002-2020 Guardsquare NV
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package proguard.classfile.editor;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
/**
* This class can add and delete attributes to and from classes, fields,
* methods, and code attributes. Attributes to be added must be filled out
* beforehand, including their references to the constant pool. Existing
* attributes of the same type are always replaced.
*
* @author Eric Lafortune
*/
public class AttributesEditor
{
private final ProgramClass targetClass;
private final ProgramMember targetMember;
private final CodeAttribute targetAttribute;
private final boolean replaceAttributes;
/**
* Creates a new AttributeAdder that will edit attributes in the given
* target class.
*/
public AttributesEditor(ProgramClass targetClass,
boolean replaceAttributes)
{
this(targetClass, null, null, replaceAttributes);
}
/**
* Creates a new AttributeAdder that will edit attributes in the given
* target class member.
*/
public AttributesEditor(ProgramClass targetClass,
ProgramMember targetMember,
boolean replaceAttributes)
{
this(targetClass, targetMember, null, replaceAttributes);
}
/**
* Creates a new AttributeAdder that will edit attributes in the given
* target code attribute.
*/
public AttributesEditor(ProgramClass targetClass,
ProgramMember targetMember,
CodeAttribute targetAttribute,
boolean replaceAttributes)
{
this.targetClass = targetClass;
this.targetMember = targetMember;
this.targetAttribute = targetAttribute;
this.replaceAttributes = replaceAttributes;
}
/**
* Finds the specified attribute in the target.
*/
public Attribute findAttribute(String attributeName)
{
// What's the target?
return
targetAttribute != null ?
findAttribute(targetAttribute.u2attributesCount,
targetAttribute.attributes,
attributeName) :
targetMember != null ?
findAttribute(targetMember.u2attributesCount,
targetMember.attributes,
attributeName) :
findAttribute(targetClass.u2attributesCount,
targetClass.attributes,
attributeName);
}
/**
* Adds the given attribute to the target.
*/
public void addAttribute(Attribute attribute)
{
// What's the target?
if (targetAttribute != null)
{
// Try to replace an existing attribute.
if (!replaceAttributes ||
!replaceAttribute(targetAttribute.u2attributesCount,
targetAttribute.attributes,
attribute))
{
// Otherwise append the attribute.
targetAttribute.attributes =
addAttribute(targetAttribute.u2attributesCount,
targetAttribute.attributes,
attribute);
targetAttribute.u2attributesCount++;
}
}
else if (targetMember != null)
{
// Try to replace an existing attribute.
if (!replaceAttributes ||
!replaceAttribute(targetMember.u2attributesCount,
targetMember.attributes,
attribute))
{
// Otherwise append the attribute.
targetMember.attributes =
addAttribute(targetMember.u2attributesCount,
targetMember.attributes,
attribute);
targetMember.u2attributesCount++;
}
}
else
{
// Try to replace an existing attribute.
if (!replaceAttributes ||
!replaceAttribute(targetClass.u2attributesCount,
targetClass.attributes,
attribute))
{
// Otherwise append the attribute.
targetClass.attributes =
addAttribute(targetClass.u2attributesCount,
targetClass.attributes,
attribute);
targetClass.u2attributesCount++;
}
}
}
/**
* Deletes the specified attribute from the target.
*/
public void deleteAttribute(String attributeName)
{
// What's the target?
if (targetAttribute != null)
{
targetAttribute.u2attributesCount =
deleteAttribute(targetAttribute.u2attributesCount,
targetAttribute.attributes,
attributeName);
}
else if (targetMember != null)
{
targetMember.u2attributesCount =
deleteAttribute(targetMember.u2attributesCount,
targetMember.attributes,
attributeName);
}
else
{
targetClass.u2attributesCount =
deleteAttribute(targetClass.u2attributesCount,
targetClass.attributes,
attributeName);
}
}
// Small utility methods.
/**
* Tries to put the given attribute in place of an existing attribute of
* the same name, returning whether it was present.
*/
private boolean replaceAttribute(int attributesCount,
Attribute[] attributes,
Attribute attribute)
{
// Find the attribute with the same name.
int index = findAttributeIndex(attributesCount,
attributes,
attribute.getAttributeName(targetClass));
if (index < 0)
{
return false;
}
attributes[index] = attribute;
return true;
}
/**
* Appends the given attribute to the given array of attributes, creating a
* new array if necessary.
*/
private Attribute[] addAttribute(int attributesCount,
Attribute[] attributes,
Attribute attribute)
{
// Is the array too small to contain the additional attribute?
if (attributes.length <= attributesCount)
{
// Create a new array and copy the attributes into it.
Attribute[] newAttributes = new Attribute[attributesCount + 1];
System.arraycopy(attributes, 0,
newAttributes, 0,
attributesCount);
attributes = newAttributes;
}
// Append the attribute.
attributes[attributesCount] = attribute;
return attributes;
}
/**
* Deletes the attributes with the given name from the given array of
* attributes, returning the new number of attributes.
*/
private int deleteAttribute(int attributesCount,
Attribute[] attributes,
String attributeName)
{
// Find the attribute.
int index = findAttributeIndex(attributesCount,
attributes,
attributeName);
if (index < 0)
{
return attributesCount;
}
// Shift the other attributes in the array.
System.arraycopy(attributes, index + 1,
attributes, index,
attributesCount - index - 1);
// Clear the last entry in the array.
attributes[--attributesCount] = null;
return attributesCount;
}
/**
* Finds the index of the attribute with the given name in the given
* array of attributes.
*/
private int findAttributeIndex(int attributesCount,
Attribute[] attributes,
String attributeName)
{
for (int index = 0; index < attributesCount; index++)
{
Attribute attribute = attributes[index];
if (attribute.getAttributeName(targetClass).equals(attributeName))
{
return index;
}
}
return -1;
}
/**
* Finds the attribute with the given name in the given
* array of attributes.
*/
private Attribute findAttribute(int attributesCount,
Attribute[] attributes,
String attributeName)
{
for (int index = 0; index < attributesCount; index++)
{
Attribute attribute = attributes[index];
if (attribute.getAttributeName(targetClass).equals(attributeName))
{
return attribute;
}
}
return null;
}
}
