com.squareup.kotlinpoet.metadata.classinspectors.JvmDescriptorUtils.kt Maven / Gradle / Ivy

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/*
 * Copyright (C) 2021 Square, Inc.
 *
 * 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
 *
 * https://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 com.squareup.kotlinpoet.metadata.classinspectors

import kotlinx.metadata.jvm.JvmFieldSignature
import kotlinx.metadata.jvm.JvmMethodSignature
import javax.lang.model.element.Element
import javax.lang.model.element.ExecutableElement
import javax.lang.model.element.NestingKind
import javax.lang.model.element.QualifiedNameable
import javax.lang.model.element.TypeElement
import javax.lang.model.element.VariableElement
import javax.lang.model.type.ArrayType
import javax.lang.model.type.DeclaredType
import javax.lang.model.type.ErrorType
import javax.lang.model.type.ExecutableType
import javax.lang.model.type.NoType
import javax.lang.model.type.NullType
import javax.lang.model.type.PrimitiveType
import javax.lang.model.type.TypeKind.BOOLEAN
import javax.lang.model.type.TypeKind.BYTE
import javax.lang.model.type.TypeKind.CHAR
import javax.lang.model.type.TypeKind.DOUBLE
import javax.lang.model.type.TypeKind.FLOAT
import javax.lang.model.type.TypeKind.INT
import javax.lang.model.type.TypeKind.LONG
import javax.lang.model.type.TypeKind.SHORT
import javax.lang.model.type.TypeMirror
import javax.lang.model.type.TypeVariable
import javax.lang.model.type.WildcardType
import javax.lang.model.util.AbstractTypeVisitor6
import javax.lang.model.util.Types

/*
 * Adapted from
 * - https://github.com/Takhion/kotlin-metadata/blob/e6de126575ad6ca10b093129b7c30d000c9b0c37/lib/src/main/kotlin/me/eugeniomarletti/kotlin/metadata/jvm/JvmDescriptorUtils.kt
 * - https://github.com/Takhion/kotlin-metadata/pull/13
 */

/**
 * For reference, see the [JVM specification, section 4.2](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.2).
 *
 * @return the name of this [Element] in its "internal form".
 */
internal val Element.internalName: String
  get() = when (this) {
    is TypeElement -> {
      when (nestingKind) {
        NestingKind.TOP_LEVEL ->
          qualifiedName.toString().replace('.', '/')
        NestingKind.MEMBER ->
          enclosingElement.internalName + "$" + simpleName
        NestingKind.LOCAL, NestingKind.ANONYMOUS ->
          error("Unsupported nesting $nestingKind")
        null ->
          error("Unsupported, nestingKind == null")
      }
    }
    is QualifiedNameable -> qualifiedName.toString().replace('.', '/')
    else -> simpleName.toString()
  }

/**
 * @return the "field descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
@Suppress("unused")
internal val NoType.descriptor: String
  get() = "V"

/**
 * @return the "field descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
internal val DeclaredType.descriptor: String
  get() = "L" + asElement().internalName + ";"

/**
 * @return the "field descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
internal val PrimitiveType.descriptor: String
  get() = when (this.kind) {
    BYTE -> "B"
    CHAR -> "C"
    DOUBLE -> "D"
    FLOAT -> "F"
    INT -> "I"
    LONG -> "J"
    SHORT -> "S"
    BOOLEAN -> "Z"
    else -> error("Unknown primitive type $this")
  }

/**
 * @see [JvmDescriptorTypeVisitor]
 */
internal fun TypeMirror.descriptor(types: Types): String =
  accept(JvmDescriptorTypeVisitor, types)

/**
 * @return the "field descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
internal fun WildcardType.descriptor(types: Types): String =
  types.erasure(this).descriptor(types)

/**
 * @return the "field descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
internal fun TypeVariable.descriptor(types: Types): String =
  types.erasure(this).descriptor(types)

/**
 * @return the "field descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
internal fun ArrayType.descriptor(types: Types): String =
  "[" + componentType.descriptor(types)

/**
 * @return the "method descriptor" of this type.
 * @see [JvmDescriptorTypeVisitor]
 */
internal fun ExecutableType.descriptor(types: Types): String {
  val parameterDescriptors = parameterTypes.joinToString(separator = "") { it.descriptor(types) }
  val returnDescriptor = returnType.descriptor(types)
  return "($parameterDescriptors)$returnDescriptor"
}

/**
 * Returns the JVM signature in the form "$Name$MethodDescriptor", for example: `equals(Ljava/lang/Object;)Z`.
 *
 * Useful for comparing with [JvmMethodSignature].
 *
 * For reference, see the [JVM specification, section 4.3](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.3).
 */
internal fun ExecutableElement.jvmMethodSignature(types: Types): String {
  return "$simpleName${asType().descriptor(types)}"
}

/**
 * Returns the JVM signature in the form "$Name:$FieldDescriptor", for example: `"value:Ljava/lang/String;"`.
 *
 * Useful for comparing with [JvmFieldSignature].
 *
 * For reference, see the [JVM specification, section 4.3](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.3).
 */
internal fun VariableElement.jvmFieldSignature(types: Types): String {
  return "$simpleName:${asType().descriptor(types)}"
}

/**
 * When applied over a type, it returns either:
 * - a "field descriptor", for example: `Ljava/lang/Object;`
 * - a "method descriptor", for example: `(Ljava/lang/Object;)Z`
 *
 * For reference, see the [JVM specification, section 4.3](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.3).
 */
internal object JvmDescriptorTypeVisitor : AbstractTypeVisitor6() {
  override fun visitNoType(t: NoType, types: Types): String = t.descriptor
  override fun visitDeclared(t: DeclaredType, types: Types): String = t.descriptor
  override fun visitPrimitive(t: PrimitiveType, types: Types): String = t.descriptor

  override fun visitArray(t: ArrayType, types: Types): String = t.descriptor(types)
  override fun visitWildcard(t: WildcardType, types: Types): String = t.descriptor(types)
  override fun visitExecutable(t: ExecutableType, types: Types): String = t.descriptor(types)
  override fun visitTypeVariable(t: TypeVariable, types: Types): String = t.descriptor(types)

  override fun visitNull(t: NullType, types: Types): String = visitUnknown(
    t, types
  )
  override fun visitError(t: ErrorType, types: Types): String = visitUnknown(
    t, types
  )

  override fun visitUnknown(t: TypeMirror, types: Types): String = error("Unsupported type $t")
}