Java annotation processing to KSP reference

Program elements

Java	Closest facility in KSP	Notes
`AnnotationMirror`	`KSAnnotation`
`AnnotationValue`	`KSValueArguments`
`Element`	`KSDeclaration`/`KSDeclarationContainer`
`ExecutableElement`	`KSFunctionDeclaration`
`PackageElement`	`KSFile`	KSP doesn't model packages as program elements
`Parameterizable`	`KSDeclaration`
`QualifiedNameable`	`KSDeclaration`
`TypeElement`	`KSClassDeclaration`
`TypeParameterElement`	`KSTypeParameter`
`VariableElement`	`KSValueParameter`/`KSPropertyDeclaration`

Types

KSP requires explicit type resolution, so some functionalities in Java can only be carried out by KSType and the corresponding elements before resolution.

Java	Closest facility in KSP	Notes
`ArrayType`	`KSBuiltIns.arrayType`
`DeclaredType`	`KSType`/`KSClassifierReference`
`ErrorType`	`KSType.isError`
`ExecutableType`	`KSType`/`KSCallableReference`
`IntersectionType`	`KSType`/`KSTypeParameter`
`NoType`	`KSType.isError`	N/A in KSP
`NullType`		N/A in KSP
`PrimitiveType`	`KSBuiltIns`	Not exactly same as primitive type in Java
`ReferenceType`	`KSTypeReference`
`TypeMirror`	`KSType`
`TypeVariable`	`KSTypeParameter`
`UnionType`	N/A	Kotlin has only one type per catch block. `UnionType` is also not observable by even Java annotation processors
`WildcardType`	`KSType`/`KSTypeArgument`

Misc

Java	Closest facility in KSP	Notes
`Name`	`KSName`
`ElementKind`	`ClassKind`/`FunctionKind`
`Modifier`	`Modifier`
`NestingKind`	`ClassKind`/`FunctionKind`
`AnnotationValueVisitor`
`ElementVisitor`	`KSVisitor`
`AnnotatedConstruct`	`KSAnnotated`
`TypeVisitor`
`TypeKind`	`KSBuiltIns`	Some can be found in builtins, otherwise check `KSClassDeclaration` for `DeclaredType`
`ElementFilter`	`Collection.filterIsInstance`
`ElementKindVisitor`	`KSVisitor`
`ElementScanner`	`KSTopDownVisitor`
`SimpleAnnotationValueVisitor`		Not needed in KSP
`SimpleElementVisitor`	`KSVisitor`
`SimpleTypeVisitor`
`TypeKindVisitor`
`Types`	`Resolver`/`utils`	Some of the `utils` are also integrated into symbol interfaces
`Elements`	`Resolver`/`utils`

Details

Element

Java	KSP equivalent
`asType`	`ksClassDeclaration.asType(...)` is available for `KSClassDeclaration` only. Type arguments need to be supplied.
`getAnnotation`	To be implemented
`getAnnotationMirrors`	`ksDeclaration.annotations`
`getEnclosedElements`	`ksDeclarationContainer.declarations`
`getEnclosingElements`	`ksDeclaration.parentDeclaration`
`getKind`	Type check and cast following `ClassKind` or `FunctionKind`
`getModifiers`	`ksDeclaration.modifiers`
`getSimpleName`	`ksDeclaration.simpleName`

ExecutableElement

Java	KSP equivalent
`getDefaultValue`	To be implemented
`getParameters`	`ksFunctionDeclaration.parameters`
`getReceiverType`	`ksFunctionDeclaration.parentDeclaration`
`getReturnType`	`ksFunctionDeclaration.returnType`
`getSimpleName`	`ksFunctionDeclaration.simpleName`
`getThrownTypes`	Not needed in Kotlin
`getTypeParameters`	`ksFunctionDeclaration.typeParameters`
`isDefault`	Check whether parent declaration is an interface or not
`isVarArgs`	`ksFunctionDeclaration.parameters.any { it.isVarArg }`

TypeElement

Java	KSP equivalent
`getEnclosedElements`	`ksClassDeclaration.declarations`
`getEnclosingElement`	`ksClassDeclaration.parentDeclaration`
`getInterfaces`	`// Should be able to do without resolution ksClassDeclaration.superTypes .map { it.resolve() } .filter { (it?.declaration as? KSClassDeclaration)?.classKind == ClassKind.INTERFACE }`
`getNestingKind`	Check `KSClassDeclaration.parentDeclaration` and `inner` modifier
`getQualifiedName`	`ksClassDeclaration.qualifiedName`
`getSimpleName`	`ksClassDeclaration.simpleName`
`getSuperclass`	`// Should be able to do without resolution ksClassDeclaration.superTypes .map { it.resolve() } .filter { (it?.declaration as? KSClassDeclaration)?.classKind == ClassKind.CLASS }`
`getTypeParameters`	`ksClassDeclaration.typeParameters`

ExecutableType

Java	KSP equivalent
`getParameterTypes`	`ksType.declaration.typeParameters`, `ksFunctionDeclaration.parameters.map { it.type }`
`getReceiverType`	`ksFunctionDeclaration.parentDeclaration.asType(...)`
`getReturnType`	`ksType.declaration.typeParameters.last()`
`getThrownTypes`	Not needed in Kotlin
`getTypeVariables`	`ksFunctionDeclaration.typeParameters`

WildcardType

Java	KSP equivalent
`getExtendsBound`	`if (ksTypeArgument.variance == Variance.COVARIANT) ksTypeArgument.type else null`
`getSuperBound`	`if (ksTypeArgument.variance == Variance.CONTRAVARIANT) ksTypeArgument.type else null`

Elements

Java	KSP equivalent
`getAllAnnotationMirrors`	`KSDeclarations.annotations`
`getAllMembers`	`getAllFunctions`, `getAllProperties` is to be implemented
`getBinaryName`	To be decided, see Java Specification
`getConstantExpression`	There is constant value, not expression
`getDocComment`	To be implemented
`getElementValuesWithDefaults`	To be implemented
`getName`	`resolver.getKSNameFromString`
`getPackageElement`	Package not supported, while package information can be retrieved. Operation on package is not possible for KSP
`getPackageOf`	Package not supported
`getTypeElement`	`Resolver.getClassDeclarationByName`
`hides`	To be implemented
`isDeprecated`	`KsDeclaration.annotations.any { it.annotationType.resolve()!!.declaration.qualifiedName!!.asString() == Deprecated::class.qualifiedName }`
`overrides`	`KSFunctionDeclaration.overrides`/`KSPropertyDeclaration.overrides` (member function of respective class)
`printElements`	KSP has basic `toString()` implementation on most classes

Types

Java	KSP equivalent
`asElement`	`ksType.declaration`
`asMemberOf`	`resolver.asMemberOf`
`boxedClass`	Not needed
`capture`	To be decided
`contains`	`KSType.isAssignableFrom`
`directSuperTypes`	`(ksType.declaration as KSClassDeclaration).superTypes`
`erasure`	`ksType.starProjection()`
`getArrayType`	`ksBuiltIns.arrayType.replace(...)`
`getDeclaredType`	`ksClassDeclaration.asType`
`getNoType`	`ksBuiltIns.nothingType`/`null`
`getNullType`	Depending on the context, `KSType.markNullable` could be useful
`getPrimitiveType`	Not needed, check for `KSBuiltins`
`getWildcardType`	Use `Variance` in places expecting `KSTypeArgument`
`isAssignable`	`ksType.isAssignableFrom`
`isSameType`	`ksType.equals`
`isSubsignature`	`functionTypeA == functionTypeB`/`functionTypeA == functionTypeB.starProjection()`
`isSubtype`	`ksType.isAssignableFrom`
`unboxedType`	Not needed