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modern java compat
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@FalsePattern
FalsePattern committed Dec 23, 2024
1 parent 82302bf commit 189c46d
Showing 1 changed file with 105 additions and 37 deletions.
142 changes: 105 additions & 37 deletions src/main/java/invtweaks/forge/asm/ClassConstantPoolParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,28 +22,68 @@
package invtweaks.forge.asm;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;

import org.objectweb.asm.Opcodes;

/**
* Using this class to search for a String reference is > 40 times faster than parsing a class with a ClassReader +
* ClassNode while using way less RAM
* Using this class to search for a (single) String reference is > 40 times faster than parsing a class with a
* ClassReader + ClassNode while using way less RAM
*/
public class ClassConstantPoolParser {

private static final int UTF8 = 1;
private static final int INT = 3;
private static final int FLOAT = 4;
private static final int LONG = 5;
private static final int DOUBLE = 6;
private static final int FIELD = 9;
private static final int METH = 10;
private static final int IMETH = 11;
private static final int NAME_TYPE = 12;
private static final int HANDLE = 15;
private static final int INDY = 18;
/** The tag value of CONSTANT_Class_info JVMS structures. */
private static final int CONSTANT_CLASS_TAG = 7;

private final byte[][] BYTES_TO_SEARCH;
/** The tag value of CONSTANT_Fieldref_info JVMS structures. */
private static final int CONSTANT_FIELDREF_TAG = 9;

/** The tag value of CONSTANT_Methodref_info JVMS structures. */
private static final int CONSTANT_METHODREF_TAG = 10;

/** The tag value of CONSTANT_InterfaceMethodref_info JVMS structures. */
private static final int CONSTANT_INTERFACE_METHODREF_TAG = 11;

/** The tag value of CONSTANT_String_info JVMS structures. */
private static final int CONSTANT_STRING_TAG = 8;

/** The tag value of CONSTANT_Integer_info JVMS structures. */
private static final int CONSTANT_INTEGER_TAG = 3;

/** The tag value of CONSTANT_Float_info JVMS structures. */
private static final int CONSTANT_FLOAT_TAG = 4;

/** The tag value of CONSTANT_Long_info JVMS structures. */
private static final int CONSTANT_LONG_TAG = 5;

/** The tag value of CONSTANT_Double_info JVMS structures. */
private static final int CONSTANT_DOUBLE_TAG = 6;

/** The tag value of CONSTANT_NameAndType_info JVMS structures. */
private static final int CONSTANT_NAME_AND_TYPE_TAG = 12;

/** The tag value of CONSTANT_Utf8_info JVMS structures. */
private static final int CONSTANT_UTF8_TAG = 1;

/** The tag value of CONSTANT_MethodHandle_info JVMS structures. */
private static final int CONSTANT_METHOD_HANDLE_TAG = 15;

/** The tag value of CONSTANT_MethodType_info JVMS structures. */
private static final int CONSTANT_METHOD_TYPE_TAG = 16;

/** The tag value of CONSTANT_Dynamic_info JVMS structures. */
private static final int CONSTANT_DYNAMIC_TAG = 17;

/** The tag value of CONSTANT_InvokeDynamic_info JVMS structures. */
private static final int CONSTANT_INVOKE_DYNAMIC_TAG = 18;

/** The tag value of CONSTANT_Module_info JVMS structures. */
private static final int CONSTANT_MODULE_TAG = 19;

/** The tag value of CONSTANT_Package_info JVMS structures. */
private static final int CONSTANT_PACKAGE_TAG = 20;

private byte[][] BYTES_TO_SEARCH;

public ClassConstantPoolParser(String... strings) {
BYTES_TO_SEARCH = new byte[strings.length][];
Expand All @@ -52,55 +92,83 @@ public ClassConstantPoolParser(String... strings) {
}
}

public void addString(String string) {
BYTES_TO_SEARCH = Arrays.copyOf(BYTES_TO_SEARCH, BYTES_TO_SEARCH.length + 1);
BYTES_TO_SEARCH[BYTES_TO_SEARCH.length - 1] = string.getBytes(StandardCharsets.UTF_8);
}

/**
* Returns true if the constant pool of the class represented by this byte array contains the String we are looking
* for
* Returns true if the constant pool of the class represented by this byte array contains one of the Strings we are
* looking for
*/
public boolean parse(byte[] basicClass) {
public boolean find(byte[] basicClass) {
return find(basicClass, false);
}

private static final int V24 = 68;

/**
* Returns true if the constant pool of the class represented by this byte array contains one of the Strings we are
* looking for.
*
* @param prefixes If true, it is enough for a constant pool entry to <i>start</i> with one of our Strings to count
* as a match - otherwise, the entire String has to match.
*/
public boolean find(byte[] basicClass, boolean prefixes) {
if (basicClass == null || basicClass.length == 0) {
return false;
}
// checks the class version
if (readShort(6, basicClass) > Opcodes.V1_8) {
if (readShort(6, basicClass) > V24) {
return false;
}
// parses the constant pool
int n = readUnsignedShort(8, basicClass);
final int n = readUnsignedShort(8, basicClass);
int index = 10;
for (int i = 1; i < n; ++i) {
int size;
final int size;
switch (basicClass[index]) {
case FIELD:
case METH:
case IMETH:
case INT:
case FLOAT:
case NAME_TYPE:
case INDY:
case CONSTANT_FIELDREF_TAG:
case CONSTANT_METHODREF_TAG:
case CONSTANT_INTERFACE_METHODREF_TAG:
case CONSTANT_INTEGER_TAG:
case CONSTANT_FLOAT_TAG:
case CONSTANT_NAME_AND_TYPE_TAG:
case CONSTANT_DYNAMIC_TAG:
case CONSTANT_INVOKE_DYNAMIC_TAG:
size = 5;
break;
case LONG:
case DOUBLE:
case CONSTANT_LONG_TAG:
case CONSTANT_DOUBLE_TAG:
size = 9;
++i;
break;
case UTF8:
case CONSTANT_UTF8_TAG:
final int strLen = readUnsignedShort(index + 1, basicClass);
size = 3 + strLen;
label: for (byte[] bytes : BYTES_TO_SEARCH) {
if (strLen == bytes.length) {
for (int j = index + 3; j < index + 3 + strLen; j++) {
for (byte[] bytes : BYTES_TO_SEARCH) {
if (prefixes ? strLen >= bytes.length : strLen == bytes.length) {
boolean found = true;
for (int j = index + 3; j < index + 3 + bytes.length; j++) {
if (basicClass[j] != bytes[j - (index + 3)]) {
continue label;
found = false;
break;
}
}
return true;
if (found) {
return true;
}
}
}
break;
case HANDLE:
case CONSTANT_METHOD_HANDLE_TAG:
size = 4;
break;
case CONSTANT_CLASS_TAG:
case CONSTANT_STRING_TAG:
case CONSTANT_METHOD_TYPE_TAG:
case CONSTANT_PACKAGE_TAG:
case CONSTANT_MODULE_TAG:
default:
size = 3;
break;
Expand All @@ -118,4 +186,4 @@ private static int readUnsignedShort(final int index, byte[] basicClass) {
return ((basicClass[index] & 0xFF) << 8) | (basicClass[index + 1] & 0xFF);
}

}
}

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