ClassFileReader: Implemented field reader

2026-10-16 07:49:44 +08:00 · 2022-09-03 18:28:48 +05:30
parent a978941ce4
commit 94b01441d3
28 changed files with 1302 additions and 37 deletions
@@ -53,4 +53,35 @@ public class ClassFileConstants {

  /** Is a module, not a class or interface. */
  public static final int ACC_MODULE = 0x8000;
+  
+  public static final String ATTR_CONSTANT_VALUE = "ConstantValue";
+  public static final String ATTR_CODE = "Code";
+  public static final String ATTR_EXCEPTIONS = "Exceptions";
+  public static final String ATTR_SOURCE_FILE = "SourceFile";
+  public static final String ATTR_LINE_NUMBER_TABLE = "LineNumberTable";
+  public static final String ATTR_LOCAL_VARIABLE_TABLE = "LocalVariableTable";
+  public static final String ATTR_INNER_CLASSES = "InnerClasses";
+  public static final String ATTR_SYNTHETIC = "Synthetic";
+  public static final String ATTR_DEPRECATED = "Deprecated";
+  public static final String ATTR_ENCLOSING_METHOD = "EnclosingMethod";
+  public static final String ATTR_SIGNATURE = "Signature";
+  public static final String ATTR_SOURCE_DEBUG_EXTENSION = "SourceDebugExtension";
+  public static final String ATTR_LOCAL_VARIABLE_TYPE_TABLE = "LocalVariableTypeTable";
+  public static final String ATTR_RUNTIME_VISIBLE_ANNOTATIONS = "RuntimeVisibleAnnotations";
+  public static final String ATTR_RUNTIME_INVISIBLE_ANNOTATIONS = "RuntimeInvisibleAnnotations";
+  public static final String ATTR_RUNTIME_VISIBLE_PARAMETER_ANNOTATIONS = "RuntimeVisibleParameterAnnotations";
+  public static final String ATTR_RUNTIME_INVISIBLE_PARAMETER_ANNOTATIONS = "RuntimeInvisibleParameterAnnotations";
+  public static final String ATTR_ANNOTATION_DEFAULT = "AnnotationDefault";
+  public static final String ATTR_STACK_MAP_TABLE = "StackMapTable";
+  public static final String ATTR_BOOTSTRAP_METHODS = "BootstrapMethods";
+  public static final String ATTR_RUNTIME_VISIBLE_TYPE_ANNOTATIONS = "RuntimeVisibleTypeAnnotations";
+  public static final String ATTR_RUNTIME_INVISIBLE_TYPE_ANNOTATIONS = "RuntimeInvisibleTypeAnnotations";
+  public static final String ATTR_METHOD_PARAMETERS = "MethodParameters";
+  public static final String ATTR_MODULE = "Module";
+  public static final String ATTR_MODULE_PACKAGES = "ModulePackages";
+  public static final String ATTR_MAIN_CLASS = "ModuleMainClass";
+  public static final String ATTR_NEST_HOST = "NestHost";
+  public static final String ATTR_NEST_MEMBERS = "NestMembers";
+  public static final String ATTR_RECORD = "Record";
+  public static final String ATTR_PERMITTED_SUBCLASSES = "PermittedSubclasses";
 }
@@ -22,6 +22,7 @@ import com.itsaky.androidide.classfile.constants.IConstant.Type.DOUBLE
 import com.itsaky.androidide.classfile.constants.IConstant.Type.LONG
 import com.itsaky.androidide.classfile.internal.ClassFile
 import com.itsaky.androidide.classfile.internal.NullConstant
+import com.itsaky.androidide.classfile.internal.NullField
 import java.io.DataInputStream
 import java.io.InputStream

@@ -31,7 +32,7 @@ import java.io.InputStream
 *
 * @author Akash Yadav
 */
-class ClassFileReader(val stream: InputStream) {
+class ClassFileReader(private val stream: InputStream) {

  /**
   * Read the class file.
@@ -48,13 +49,15 @@ class ClassFileReader(val stream: InputStream) {
    }

    val file = ClassFile()
-    file.minorVersion = input.readUnsignedShort()
-    file.majorVersion = input.readUnsignedShort()
-
-    if (file.majorVersion >= 56 && file.minorVersion != 0 && file.minorVersion != 65535) {
+    val minorVersion = input.readUnsignedShort()
+    val majorVersion = input.readUnsignedShort()
+    
+    if (majorVersion >= 56 && minorVersion != 0 && minorVersion != 65535) {
      // When major version is >= 56, minor version must be 0 or 65535
-      throw IllegalStateException("Invalid class file minor version: '${file.minorVersion}'")
+      throw IllegalStateException("Invalid class file minor version: '${minorVersion}'")
    }
+  
+    file.version = ClassFileVersion.get(majorVersion, minorVersion)

    val poolCount = input.readUnsignedShort()
    file.constantPool = Array(poolCount) { NullConstant }
@@ -63,27 +66,36 @@ class ClassFileReader(val stream: InputStream) {
    while (index < poolCount) {
      val constant = readPoolConstant(input)
      file.constantPool[index] = constant
-  
+
      if (constant.type == LONG || constant.type == DOUBLE) {
        ++index
      }
-      
+
      ++index
    }

    file.accessFlags = input.readUnsignedShort()
    file.thisClass = input.readUnsignedShort()
    file.superClass = input.readUnsignedShort()
-    
+
    val interfaceCount = input.readUnsignedShort()
    file.interfaces = IntArray(interfaceCount)
-    
+
    index = 0
    while (index < interfaceCount) {
      file.interfaces[index] = input.readUnsignedShort()
      ++index
    }

+    val fieldCount = input.readUnsignedShort()
+    file.fields = Array(fieldCount) { NullField }
+
+    index = 0
+    while (index < fieldCount) {
+      file.fields[index] = IFieldInfo.read(input, file)
+      ++index
+    }
+
    return file
  }

@@ -0,0 +1,51 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile
+
+/**
+ * Version info for the class file.
+ *
+ * @author Akash Yadav
+ */
+enum class ClassFileVersion(val major: Int, val minor: Int) {
+  JAVA_1_0(45, 0),
+  JAVA_1_1(45, 3),
+  JAVA_1_2(46, 0),
+  JAVA_1_3(47, 0),
+  JAVA_1_4(48, 0),
+  JAVA_5(49, 0),
+  JAVA_6(50, 0),
+  JAVA_7(51, 0),
+  JAVA_8(52, 0),
+  JAVA_9(53, 0),
+  JAVA_10(54, 0),
+  JAVA_11(55, 0),
+  JAVA_12(56, 0),
+  JAVA_13(57, 0),
+  JAVA_14(58, 0),
+  JAVA_15(59, 0),
+  JAVA_16(60, 0),
+  JAVA_17(61, 0);
+
+  companion object {
+    internal fun get(major: Int, minor: Int): ClassFileVersion {
+      return values().firstOrNull { it.major == major && it.minor == minor }
+        ?: throw IllegalArgumentException("Unknown class file version '${major}.${minor}'")
+    }
+  }
+}
@@ -25,11 +25,9 @@ import com.itsaky.androidide.classfile.constants.IConstant
 * @author Akash Yadav
 */
 interface IClassFile {
-  /** Major version of the class file. */
-  val majorVersion: Int

-  /** Minor version of the class file. */
-  val minorVersion: Int
+  /** The class file version. */
+  val version: ClassFileVersion

  /** The constant pool. */
  val constantPool: Array<IConstant>
@@ -52,6 +50,9 @@ interface IClassFile {
  /** The interfaces that this class implements. */
  val interfaces: IntArray

+  /** The fields of this class. */
+  val fields: Array<IFieldInfo>
+
  /** Get the string representation of this class' name. */
  fun getName(): String

@@ -0,0 +1,66 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile
+
+import com.itsaky.androidide.classfile.attributes.IAttribute
+import com.itsaky.androidide.classfile.internal.ClassFile
+import com.itsaky.androidide.classfile.internal.FieldInfo
+import com.itsaky.androidide.classfile.internal.NullAttribute
+import java.io.DataInputStream
+
+/**
+ * Information about a field.
+ *
+ * @author Akash Yadav
+ */
+interface IFieldInfo {
+
+  /** Access flags for this field. */
+  val accessFlags: Int
+
+  /** The index in the constant pool which corresponds to the name of this field. */
+  val nameIndex: Int
+
+  /**
+   * The index in the constant pool which corresponds to the field descriptor string for this field.
+   */
+  val descriptorIndex: Int
+
+  /** The attributes of this field. */
+  val attributes: Array<IAttribute>
+
+  companion object {
+
+    internal fun read(input: DataInputStream, file: ClassFile): IFieldInfo {
+      val field = FieldInfo()
+      field.accessFlags = input.readUnsignedShort()
+      field.nameIndex = input.readUnsignedShort()
+      field.descriptorIndex = input.readUnsignedShort()
+
+      val attrCount = input.readUnsignedShort()
+      field.attributes = Array(attrCount) { NullAttribute }
+
+      var index = 0
+      while (index < attrCount) {
+        field.attributes[index] = IAttribute.read(input, file)
+        ++index
+      }
+      return field
+    }
+  }
+}
@@ -0,0 +1,52 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import java.io.DataInputStream
+
+/**
+ * Annotation model for annotation based attributes in class files.
+ *
+ * @author Akash Yadav
+ */
+open class Annotation {
+
+  /**
+   * Index of the entry in the constant pool which corresponds to the type of the the annotation.
+   * The entry at this index is always an UTF-8 constant.
+   */
+  var typeIndex: Int = -1
+    internal set
+
+  /** The element value pairs. */
+  open var elementValues: Array<Pair<Int, ElementValue>> = emptyArray()
+    internal set
+
+  companion object {
+    internal fun read(input: DataInputStream): Annotation {
+      val annotation = Annotation()
+      annotation.typeIndex = input.readUnsignedShort()
+
+      val valueCount = input.readUnsignedShort()
+      annotation.elementValues =
+        Array(valueCount) { input.readUnsignedShort() to ElementValue.read(input) }
+
+      return annotation
+    }
+  }
+}
@@ -0,0 +1,40 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.ClassFileVersion.JAVA_5
+import com.itsaky.androidide.classfile.IClassFile
+import java.io.DataInputStream
+
+/**
+ * An attribute which stores information about annotations.
+ *
+ * @author Akash Yadav
+ */
+abstract class AnnotationAttr(nameIndex: Int) : BaseAttribute(nameIndex) {
+  override val version: ClassFileVersion = JAVA_5
+
+  /** The annotations. */
+  var annotations: Array<Annotation> = emptyArray()
+
+  override fun read(attrLength: Int, file: IClassFile, input: DataInputStream) {
+    val count = input.readUnsignedShort()
+    this.annotations = Array(count) { Annotation.read(input) }
+  }
+}
@@ -0,0 +1,25 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+/**
+ * Base class for attrbutes.
+ *
+ * @author Akash Yadav
+ */
+abstract class BaseAttribute(override val nameIndex: Int): IAttribute
@@ -0,0 +1,43 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.ClassFileVersion.JAVA_1_2
+import com.itsaky.androidide.classfile.IClassFile
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.CONSTANT_VALUE
+import java.io.DataInputStream
+
+/**
+ * Constant value for a field.
+ *
+ * @author Akash Yadav
+ */
+class ConstantValueAttr(nameIndex: Int) : BaseAttribute(nameIndex) {
+  override val version: ClassFileVersion = JAVA_1_2
+  override val type: Type = CONSTANT_VALUE
+
+  /** The index in the constant pool which corresponds to the value of this constant. */
+  var valueIndex: Int = -1
+    internal set
+  
+  override fun read(attrLength: Int, file: IClassFile, input: DataInputStream) {
+    this.valueIndex = input.readUnsignedShort()
+  }
+}
@@ -0,0 +1,28 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileVersion.JAVA_1_1
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.DEPRECATED
+
+/**
+ * Indicates that a class, field or method is deprecated.
+ *
+ * @author Akash Yadav
+ */
+class DeprecatedAttr(nameIndex: Int) : MarkerAttribute(nameIndex, DEPRECATED, JAVA_1_1)
@@ -0,0 +1,140 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.attributes.ElementValue.Type.ANNOTATION_INTERFACE
+import com.itsaky.androidide.classfile.attributes.ElementValue.Type.ARRAY_TYPE
+import com.itsaky.androidide.classfile.attributes.ElementValue.Type.CLASS
+import com.itsaky.androidide.classfile.attributes.ElementValue.Type.ENUM_CLASS
+import com.itsaky.androidide.classfile.attributes.ElementValue.Type.UNKNOWN
+import java.io.DataInputStream
+
+/**
+ * The element value in an annotation.
+ *
+ * @author Akash Yadav
+ */
+class ElementValue {
+
+  /** The element tag. */
+  var type: Type = UNKNOWN
+    internal set
+
+  /**
+   * The constant value if the [type] is one of the following :
+   *
+   * - [Type.BYTE]
+   * - [Type.CHAR]
+   * - [Type.DOUBLE]
+   * - [Type.FLOAT]
+   * - [Type.INT]
+   * - [Type.LONG]
+   * - [Type.SHORT]
+   * - [Type.BOOLEAN]
+   * - [Type.STRING]
+   */
+  var constValIndex: Int = -1
+    internal set
+
+  /** The element constant value if the [type] is [Type.ENUM_CLASS]. */
+  var enumValue: EnumConstValue? = null
+    internal set
+
+  /** The class name index if the [type] is [Type.CLASS]. */
+  var classNameIndex: Int = -1
+    internal set
+
+  /** The annotation constant value if the [type] is [Type.ANNOTATION_INTERFACE]. */
+  var annotationValue: Annotation? = null
+    internal set
+
+  /** The array constant value if the [type] is [Type.ARRAY_TYPE]. */
+  var arrayValue: Array<ElementValue>? = null
+    internal set
+
+  companion object {
+    internal fun read(input: DataInputStream): ElementValue {
+      val value = ElementValue()
+      value.type = Type.forTag(input.readUnsignedByte())
+      when (value.type) {
+        ENUM_CLASS -> value.enumValue = EnumConstValue.read(input)
+        CLASS -> value.classNameIndex = input.readUnsignedShort()
+        ANNOTATION_INTERFACE -> value.annotationValue = Annotation.read(input)
+        ARRAY_TYPE -> {
+          val count = input.readUnsignedShort()
+          val nullElem = ElementValue()
+          value.arrayValue = Array(count) { nullElem }
+
+          var index = 0
+          while (index < count) {
+            value.arrayValue!![index] = read(input)
+            ++index
+          }
+        }
+        else -> value.constValIndex = input.readUnsignedShort()
+      }
+
+      return value
+    }
+  }
+
+  /**
+   * The enum constant value.
+   *
+   * @property typeNameIndex The index of the entry in the constant pool which corresponds to the
+   * name of the type of this constant.
+   * @property constNameIndex The index of the entry in the constant pool which corresponds to the
+   * name of this constant.
+   */
+  data class EnumConstValue(val typeNameIndex: Int, val constNameIndex: Int) {
+    companion object {
+      internal fun read(input: DataInputStream): EnumConstValue {
+        return EnumConstValue(input.readUnsignedShort(), input.readUnsignedShort())
+      }
+    }
+  }
+
+  /** The type of [ElementValue]. */
+  enum class Type(val tag: Int) {
+    BYTE('B'.code),
+    CHAR('C'.code),
+    DOUBLE('D'.code),
+    FLOAT('F'.code),
+    INT('I'.code),
+    LONG('J'.code),
+    SHORT('S'.code),
+    BOOLEAN('Z'.code),
+    STRING('s'.code),
+    ENUM_CLASS('e'.code),
+    CLASS('c'.code),
+    ANNOTATION_INTERFACE('@'.code),
+    ARRAY_TYPE('['.code),
+
+    /** **FOR INTERNAL USE ONLY** */
+    UNKNOWN('-'.code);
+
+    companion object {
+
+      /** Get the element type for the given tag value. */
+      internal fun forTag(tag: Int): Type {
+        return values().firstOrNull { it.tag == tag }
+          ?: throw IllegalArgumentException("Invalid tag for element value type tag '$tag'")
+      }
+    }
+  }
+}
@@ -0,0 +1,106 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_CONSTANT_VALUE
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_DEPRECATED
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_RUNTIME_INVISIBLE_ANNOTATIONS
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_RUNTIME_INVISIBLE_TYPE_ANNOTATIONS
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_RUNTIME_VISIBLE_ANNOTATIONS
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_RUNTIME_VISIBLE_TYPE_ANNOTATIONS
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_SIGNATURE
+import com.itsaky.androidide.classfile.ClassFileConstants.ATTR_SYNTHETIC
+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.IClassFile
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.CONSTANT_VALUE
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.DEPRECATED
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_INVISIBLE_ANNOTATIONS
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_INVISIBLE_TYPE_ANNOTATIONS
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_VISIBLE_ANNOTATIONS
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_VISIBLE_TYPE_ANNOTATIONS
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.SIGNATURE
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.SYNTHETIC
+import com.itsaky.androidide.classfile.constants.Utf8Constant
+import com.itsaky.androidide.classfile.internal.ClassFile
+import java.io.DataInputStream
+
+/**
+ * Base class for all attributes in a class, field or method.
+ *
+ * @author Akash Yadav
+ */
+interface IAttribute {
+
+  /** The version of the class file in which this attribute appears. */
+  val version: ClassFileVersion
+
+  /** The index of the entry in the constant pool which represents the name of this attrbute. */
+  val nameIndex: Int
+
+  /** The type of attribute. */
+  val type: Type
+
+  /**
+   * **FOR INTERNAL USE ONLY**
+   *
+   * Read further information from the given input.
+   */
+  fun read(attrLength: Int, file: IClassFile, input: DataInputStream)
+
+  enum class Type(val attrName: String) {
+    CONSTANT_VALUE(ATTR_CONSTANT_VALUE),
+    SYNTHETIC(ATTR_SYNTHETIC),
+    SIGNATURE(ATTR_SIGNATURE),
+    DEPRECATED(ATTR_DEPRECATED),
+    RUNTIME_VISIBLE_ANNOTATIONS(ATTR_RUNTIME_VISIBLE_ANNOTATIONS),
+    RUNTIME_INVISIBLE_ANNOTATIONS(ATTR_RUNTIME_INVISIBLE_ANNOTATIONS),
+    RUNTIME_VISIBLE_TYPE_ANNOTATIONS(ATTR_RUNTIME_VISIBLE_TYPE_ANNOTATIONS),
+    RUNTIME_INVISIBLE_TYPE_ANNOTATIONS(ATTR_RUNTIME_INVISIBLE_TYPE_ANNOTATIONS);
+
+    companion object {
+      internal fun forName(name: String): Type {
+        return values().firstOrNull { it.attrName == name }
+          ?: throw IllegalArgumentException("Unknown attribute '$name'")
+      }
+    }
+  }
+
+  companion object {
+    internal fun read(input: DataInputStream, file: ClassFile): IAttribute {
+      val nameIndex = input.readUnsignedShort()
+      val attrLength = input.readInt()
+      val name = (file.constantPool[nameIndex] as Utf8Constant).content()
+      val type = Type.forName(name)
+      return createForType(type, nameIndex).also { it.read(attrLength, file, input) }
+    }
+
+    private fun createForType(type: Type, nameIndex: Int): IAttribute {
+      return when (type) {
+        CONSTANT_VALUE -> ConstantValueAttr(nameIndex)
+        SYNTHETIC -> SyntheticAttr(nameIndex)
+        SIGNATURE -> SignatureAttr(nameIndex)
+        DEPRECATED -> DeprecatedAttr(nameIndex)
+        RUNTIME_VISIBLE_ANNOTATIONS -> RuntimeVisibleAnnotationsAttr(nameIndex)
+        RUNTIME_INVISIBLE_ANNOTATIONS -> RuntimeVisibleAnnotationsAttr(nameIndex)
+        RUNTIME_VISIBLE_TYPE_ANNOTATIONS -> RuntimeVisibleTypeAnnotations(nameIndex)
+        RUNTIME_INVISIBLE_TYPE_ANNOTATIONS -> RuntimeInvisibleTypeAnnotations(nameIndex)
+        else -> throw IllegalArgumentException("Unknown attribute type $type")
+      }
+    }
+  }
+}
@@ -0,0 +1,36 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.IClassFile
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import java.io.DataInputStream
+
+/**
+ * An attribute which is simply a marker and does not contain any further information.
+ *
+ * @author Akash Yadav
+ */
+abstract class MarkerAttribute(
+  nameIndex: Int,
+  override val type: Type,
+  override val version: ClassFileVersion
+) : BaseAttribute(nameIndex) {
+  override fun read(attrLength: Int, file: IClassFile, input: DataInputStream) {}
+}
@@ -0,0 +1,31 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_INVISIBLE_ANNOTATIONS
+
+/**
+ * Stores run-time invisible annotations on the declaration of the corresponding class, method,
+ * field, or record component.
+ *
+ * @author Akash Yadav
+ */
+class RuntimeInvisibleAnnotationsAttr(nameIndex: Int) : AnnotationAttr(nameIndex) {
+  override val type: Type = RUNTIME_INVISIBLE_ANNOTATIONS
+}
@@ -0,0 +1,37 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_INVISIBLE_TYPE_ANNOTATIONS
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_VISIBLE_TYPE_ANNOTATIONS
+
+/**
+ * Stores run-time invisible annotations on type parameter declarations of generic classes,
+ * interfaces, methods, and constructors.
+ *
+ * @author Akash Yadav
+ */
+class RuntimeInvisibleTypeAnnotations(nameIndex: Int) : AnnotationAttr(nameIndex) {
+  override val type: Type = RUNTIME_INVISIBLE_TYPE_ANNOTATIONS
+  
+  /**
+   * The annotations always of type [TypeAnnotation]
+   */
+  var typeAnnotations: Array<TypeAnnotation> = emptyArray()
+}
@@ -0,0 +1,30 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_VISIBLE_ANNOTATIONS
+
+/**
+ * Stores run-time visible annotations on the declaration of the corresponding class, field, method,
+ * or record component.
+ * @author Akash Yadav
+ */
+class RuntimeVisibleAnnotationsAttr(nameIndex: Int) : AnnotationAttr(nameIndex) {
+  override val type: Type = RUNTIME_VISIBLE_ANNOTATIONS
+}
@@ -0,0 +1,36 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.RUNTIME_VISIBLE_TYPE_ANNOTATIONS
+
+/**
+ * Stores run-time visible annotations on type parameter declarations of generic classes,
+ * interfaces, methods, and constructors.
+ *
+ * @author Akash Yadav
+ */
+class RuntimeVisibleTypeAnnotations(nameIndex: Int) : AnnotationAttr(nameIndex) {
+  override val type: Type = RUNTIME_VISIBLE_TYPE_ANNOTATIONS
+  
+  /**
+   * The annotations always of type [TypeAnnotation]
+   */
+  var typeAnnotations: Array<TypeAnnotation> = emptyArray()
+}
@@ -0,0 +1,42 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.ClassFileVersion.JAVA_5
+import com.itsaky.androidide.classfile.IClassFile
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.SIGNATURE
+import java.io.DataInputStream
+
+/**
+ * Signature of a class, field or method.
+ *
+ * @author Akash Yadav
+ */
+class SignatureAttr(nameIndex: Int) : BaseAttribute(nameIndex) {
+  override val version: ClassFileVersion = JAVA_5
+  override val type: Type = SIGNATURE
+  
+  var signatureIndex: Int = -1
+    internal set
+  
+  override fun read(attrLength: Int, file: IClassFile, input: DataInputStream) {
+    this.signatureIndex = input.readUnsignedShort()
+  }
+}
@@ -0,0 +1,28 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import com.itsaky.androidide.classfile.ClassFileVersion.JAVA_1_1
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type.SYNTHETIC
+
+/**
+ * Indicates that a class, field or method is synthetic.
+ *
+ * @author Akash Yadav
+ */
+class SyntheticAttr(nameIndex: Int) : MarkerAttribute(nameIndex, SYNTHETIC, JAVA_1_1)
@@ -0,0 +1,59 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import java.io.DataInputStream
+
+/**
+ * Annotation model for (in)visible type annotations.
+ *
+ * @author Akash Yadav
+ */
+class TypeAnnotation {
+
+  lateinit var targetInfo: TargetInfo
+    internal set
+
+  lateinit var typePath: TypePath
+    internal set
+
+  /**
+   * Index of the entry in the constant pool which corresponds to the type of the the annotation.
+   * The entry at this index is always an UTF-8 constant.
+   */
+  var typeIndex: Int = -1
+    internal set
+
+  /** The element value pairs. */
+  var elementValues: Array<Pair<Int, ElementValue>> = emptyArray()
+    internal set
+
+  companion object {
+    internal fun read(input: DataInputStream): TypeAnnotation {
+      val annotation = TypeAnnotation()
+      val targetType = input.readUnsignedByte()
+      annotation.targetInfo = TargetInfo.forType(targetType).apply { read(input) }
+      annotation.typePath = TypePath().apply { read(input) }
+      annotation.typeIndex = input.readUnsignedShort()
+      val valueCount = input.readUnsignedShort()
+      annotation.elementValues =
+        Array(valueCount) { input.readUnsignedShort() to ElementValue.read(input) }
+      return annotation
+    }
+  }
+}
@@ -0,0 +1,54 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import java.io.DataInputStream
+
+/**
+ * Wherever a type is used in a declaration or expression, the type_path structure identifies which
+ * part of the type is annotated. An annotation may appear on the type itself, but if the type is a
+ * reference type, then there are additional locations where an annotation may appear.
+ *
+ * @author Akash Yadav
+ */
+class TypePath {
+
+  var paths: Array<PathEntry> = emptyArray()
+    internal set
+
+  class PathEntry {
+    var typePathKind: Int = -1
+      internal set
+    var typeArgumentIndex: Int = -1
+      internal set
+
+    internal fun read(input: DataInputStream) {
+      this.typePathKind = input.readUnsignedByte()
+      this.typeArgumentIndex = input.readUnsignedByte()
+    }
+  }
+
+  internal fun read(input: DataInputStream) {
+    this.paths =
+      Array(input.readUnsignedByte()) {
+        val entry = PathEntry()
+        entry.read(input)
+        entry
+      }
+  }
+}
@@ -0,0 +1,210 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.attributes
+
+import java.io.DataInputStream
+
+/**
+ * Target information in a type annotation.
+ *
+ * @author Akash Yadav
+ */
+abstract class TargetInfo(val currentType: Int, val types: IntArray) {
+
+  /** The read the target info. */
+  internal abstract fun read(input: DataInputStream)
+
+  companion object {
+
+    internal fun forType(type: Int): TargetInfo {
+      return when (type) {
+        0x00,
+        0x01 -> TypeParameterTarget(type)
+        0x10 -> SupertypeTarget(type)
+        0x11,
+        0x12 -> TypeParameterBoundTarget(type)
+        0x13,
+        0x14,
+        0x15 -> EmptyTarget(type)
+        0x16 -> FormalParameterTarget(type)
+        0x17 -> ThrowsTarget(type)
+        0x40,
+        0x41 -> LocalVarTarget(type)
+        0x42 -> CatchTarget(type)
+        0x43,
+        0x44,
+        0x45,
+        0x46 -> OffsetTarget(type)
+        0x47,
+        0x48,
+        0x49,
+        0x4A,
+        0x4B -> TypeArgumentTarget(type)
+        else -> throw IllegalArgumentException("Unknown type parameter target")
+      }
+    }
+  }
+}
+
+open class TypeParameterTarget
+@JvmOverloads
+constructor(currentType: Int, types: IntArray = intArrayOf(0x00, 0x01)) :
+  TargetInfo(currentType, types) {
+
+  /**
+   * The value of the type_parameter_index item specifies which type parameter declaration is
+   * annotated. A type_parameter_index value of 0 specifies the first type parameter declaration.
+   */
+  var typeParameterIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.typeParameterIndex = input.readUnsignedByte()
+  }
+}
+
+class SupertypeTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x10)) {
+
+  /**
+   * A supertype_index value of 65535 specifies that the annotation appears on the superclass in an
+   * extends clause of a class declaration.
+   *
+   * Any other supertype_index value is an index into the interfaces array of the enclosing
+   * ClassFile structure, and specifies that the annotation appears on that superinterface in either
+   * the implements clause of a class declaration or the extends clause of an interface declaration.
+   */
+  var supertypeIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.supertypeIndex = input.readUnsignedShort()
+  }
+}
+
+class TypeParameterBoundTarget(currentType: Int) :
+  TypeParameterTarget(currentType, intArrayOf(0x11, 0x12)) {
+
+  /**
+   * The value of the bound_index item specifies which bound of the type parameter declaration
+   * indicated by type_parameter_index is annotated. A bound_index value of 0 specifies the first
+   * bound of a type parameter declaration.
+   */
+  var boundIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    super.read(input)
+    this.boundIndex = input.readUnsignedShort()
+  }
+}
+
+class EmptyTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x13, 0x14, 0x15)) {
+
+  override fun read(input: DataInputStream) {}
+}
+
+class FormalParameterTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x16)) {
+
+  /**
+   * The value of the formal_parameter_index item specifies which formal parameter declaration has
+   * an annotated type. A formal_parameter_index value of i may, but is not required to, correspond
+   * to the i'th parameter descriptor in the method descriptor.
+   */
+  var formalParameterIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.formalParameterIndex = input.readUnsignedByte()
+  }
+}
+
+class ThrowsTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x17)) {
+
+  /**
+   * The value of the throws_type_index item is an index into the exception_index_table array of the
+   * Exceptions attribute of the method_info structure enclosing the RuntimeVisibleTypeAnnotations
+   * attribute.
+   */
+  var throwsTypeIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.throwsTypeIndex = input.readUnsignedShort()
+  }
+}
+
+class LocalVarTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x40, 0x41)) {
+
+  var table: Array<LocalVarTagetTableEntry> = emptyArray()
+
+  class LocalVarTagetTableEntry {
+    var startPc: Int = -1
+      internal set
+    var length: Int = -1
+      internal set
+    var index: Int = -1
+      internal set
+  }
+
+  override fun read(input: DataInputStream) {
+    val length = input.readUnsignedShort()
+    this.table =
+      Array(length) {
+        val entry = LocalVarTagetTableEntry()
+        entry.startPc = input.readUnsignedShort()
+        entry.length = input.readUnsignedShort()
+        entry.index = input.readUnsignedShort()
+        entry
+      }
+  }
+}
+
+class CatchTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x42)) {
+
+  var exceptionTableIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.exceptionTableIndex = input.readUnsignedShort()
+  }
+}
+
+class OffsetTarget(currentType: Int) : TargetInfo(currentType, intArrayOf(0x43, 0x44, 0x45, 0x46)) {
+
+  var offset: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.offset = input.readUnsignedShort()
+  }
+}
+
+class TypeArgumentTarget(currentType: Int) :
+  TargetInfo(currentType, intArrayOf(0x47, 0x48, 0x49, 0x4A, 0x4B)) {
+
+  var offset: Int = -1
+    internal set
+
+  var typeArgumentIndex: Int = -1
+    internal set
+
+  override fun read(input: DataInputStream) {
+    this.offset = input.readUnsignedShort()
+    this.typeArgumentIndex = input.readUnsignedByte()
+  }
+}
@@ -33,6 +33,9 @@ class Utf8Constant : IConstant {
  var bytes: ByteArray = ByteArray(0)
    private set

+  /** Get the string represented by this constant. */
+  fun content() = this.bytes.decodeToString()
+
  override fun read(input: DataInputStream) {
    val length = input.readUnsignedShort()
    this.bytes = ByteArray(length)
@@ -56,6 +59,6 @@ class Utf8Constant : IConstant {
  }

  override fun toString(): String {
-    return "Utf8Constant(type=$type, bytes=${bytes.contentToString()}, bytesAsString=${bytes.decodeToString()})"
+    return "Utf8Constant(type=$type, bytes=${bytes.contentToString()}, bytesAsString=${content()})"
  }
 }
@@ -17,8 +17,11 @@

 package com.itsaky.androidide.classfile.internal

+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.ClassFileVersion.JAVA_1_0
 import com.itsaky.androidide.classfile.constants.IConstant
 import com.itsaky.androidide.classfile.IClassFile
+import com.itsaky.androidide.classfile.IFieldInfo
 import com.itsaky.androidide.classfile.constants.ClassConstant
 import com.itsaky.androidide.classfile.constants.Utf8Constant

@@ -29,31 +32,13 @@ import com.itsaky.androidide.classfile.constants.Utf8Constant
 */
 internal class ClassFile : IClassFile {
  
-  /** Major version of the class file. */
-  override var majorVersion: Int = 0
-
-  /** Minor version of the class file. */
-  override var minorVersion: Int = 0
-
-  /** The constant pool. */
+  override var version: ClassFileVersion = JAVA_1_0
  override var constantPool: Array<IConstant> = emptyArray()
-
-  /** Access flags for the class. */
  override var accessFlags: Int = 0
-
-  /**
-   * The index in the constant pool which corresponds to the internal representation of the name of
-   * this class.
-   */
  override var thisClass: Int = -1
-
-  /**
-   * The index in the constant pool which corresponds to the internal representation of the name of
-   * the super class of this class.
-   */
  override var superClass: Int = -1
-  
  override var interfaces: IntArray = IntArray(0)
+  override var fields: Array<IFieldInfo> = emptyArray()
  
  override fun getName(): String {
    val entry = constantPool[thisClass]
@@ -0,0 +1,37 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.internal
+
+import com.itsaky.androidide.classfile.IFieldInfo
+import com.itsaky.androidide.classfile.attributes.IAttribute
+
+/**
+ * Default internal implementation of [IFieldInfo].
+ *
+ * @author Akash Yadav
+ */
+internal class FieldInfo : IFieldInfo {
+  override var accessFlags: Int = 0
+    internal set
+  override var nameIndex: Int = -1
+    internal set
+  override var descriptorIndex: Int = -1
+    internal set
+  override var attributes: Array<IAttribute> = emptyArray()
+    internal set
+}
@@ -0,0 +1,44 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.internal
+
+import com.itsaky.androidide.classfile.ClassFileVersion
+import com.itsaky.androidide.classfile.IClassFile
+import com.itsaky.androidide.classfile.attributes.IAttribute
+import com.itsaky.androidide.classfile.attributes.IAttribute.Type
+import java.io.DataInputStream
+
+/**
+ * **FOR INTERNAL USE ONLY**
+ *
+ * Represents a null attribute. Not present in a class file.
+ *
+ * @author Akash Yadav
+ */
+internal object NullAttribute : IAttribute {
+  override val version: ClassFileVersion
+    get() = throw UnsupportedOperationException()
+  override val nameIndex: Int
+    get() = throw UnsupportedOperationException()
+  override val type: Type
+    get() = throw UnsupportedOperationException()
+
+  override fun read(attrLength: Int, file: IClassFile, input: DataInputStream) {
+    throw UnsupportedOperationException()
+  }
+}
@@ -0,0 +1,39 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.classfile.internal
+
+import com.itsaky.androidide.classfile.IFieldInfo
+import com.itsaky.androidide.classfile.attributes.IAttribute
+
+/**
+ * **FOR INTERNAL USE ONLY**
+ *
+ * Represents a null field. Not available in class file.
+ *
+ * @author Akash Yadav
+ */
+internal object NullField : IFieldInfo {
+  override val accessFlags: Int
+    get() = throw UnsupportedOperationException()
+  override val nameIndex: Int
+    get() = throw UnsupportedOperationException()
+  override val descriptorIndex: Int
+    get() = throw UnsupportedOperationException()
+  override val attributes: Array<IAttribute>
+    get() = throw UnsupportedOperationException()
+}
@@ -39,8 +39,7 @@ class ClassFileReaderTest {
    val file = reader.read()

    assertThat(file).isNotNull()
-    assertThat(file.majorVersion).isEqualTo(55)
-    assertThat(file.minorVersion).isEqualTo(0)
+    assertThat(file.version).isEqualTo(ClassFileVersion.JAVA_11)

    assertThat(file.getName()).isEqualTo("io/github/rosemoe/sora/widget/CodeEditor")
    assertThat(file.getSuperClassName()).isEqualTo("android/view/View")