XElement.kt
/*
* Copyright (C) 2020 The Android Open Source Project
*
* 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 androidx.room.compiler.processing
import androidx.room.compiler.processing.javac.JavacElement
import androidx.room.compiler.processing.ksp.KSFileAsOriginatingElement
import androidx.room.compiler.processing.ksp.KspFileMemberContainer
import androidx.room.compiler.processing.ksp.KspTypeElement
import androidx.room.compiler.processing.ksp.wrapAsOriginatingElement
import javax.lang.model.element.Element
import kotlin.contracts.contract
/**
* Represents an element declared in code.
*
* @see [javax.lang.model.element.Element]
* @see XExecutableElement
* @see XVariableElement
* @see XTypeElement
*/
interface XElement : XAnnotated {
/** The simple name of the element. */
val name: String
/**
* Returns the string representation of the Element's kind.
*/
fun kindName(): String
/**
* When the location of an element is unknown, this String is appended to the diagnostic
* message. Without this information, developer gets no clue on where the error is.
*/
val fallbackLocationText: String
/**
* The documentation comment of the element, or null if there is none.
*/
val docComment: String?
/**
* Returns true if all types referenced by this element are valid, i.e. resolvable.
*/
fun validate(): Boolean
/**
* Returns the immediate enclosing element. This uses Element.getEnclosingElement() on the
* Java side, and KSNode.parent on the KSP side. For non-nested classes we return null.
* For fields declared in primary constructors in Kotlin we return
* the enclosing type, not the constructor. For top-level properties or functions in Kotlin
* we return JavacTypeElement on the Javac/KAPT side and KspFileMemberContainer or
* KspSyntheticFileMemberContainer on the KSP side.
*/
val enclosingElement: XElement?
/**
* Returns the closest member container. Could be the element if it's itself a member container.
*/
val closestMemberContainer: XMemberContainer
}
/**
* Checks whether this element represents an [XTypeElement].
*/
// we keep these as extension methods to be able to use contracts
fun XElement.isTypeElement(): Boolean {
contract {
returns(true) implies (this@isTypeElement is XTypeElement)
}
return this is XTypeElement
}
/**
* Checks whether this element represents an [XEnumTypeElement].
*/
fun XElement.isEnum(): Boolean {
contract {
returns(true) implies (this@isEnum is XEnumTypeElement)
}
return this is XEnumTypeElement
}
/**
* Checks whether this element represents an [XVariableElement].
*/
fun XElement.isVariableElement(): Boolean {
contract {
returns(true) implies (this@isVariableElement is XVariableElement)
}
return this is XVariableElement
}
/**
* Checks whether this element represents an [XFieldElement].
*/
fun XElement.isField(): Boolean {
contract {
returns(true) implies (this@isField is XFieldElement)
}
return this is XFieldElement
}
/**
* Checks whether this element represents an [XMethodElement].
*/
fun XElement.isMethod(): Boolean {
contract {
returns(true) implies (this@isMethod is XMethodElement)
}
return this is XMethodElement
}
/**
* Checks whether this element represents an [XExecutableParameterElement].
*/
fun XElement.isMethodParameter(): Boolean {
contract {
returns(true) implies (this@isMethodParameter is XExecutableParameterElement)
}
return this is XExecutableParameterElement
}
/**
* Checks whether this element represents an [XConstructorElement].
*/
fun XElement.isConstructor(): Boolean {
contract {
returns(true) implies (this@isConstructor is XConstructorElement)
}
return this is XConstructorElement
}
/**
* Attempts to get a Javac [Element] representing the originating element for attribution
* when writing a file for incremental processing.
*
* In KSP a synthetic javac element will be returned, which allows us to pass originating elements
* to JavaPoet and KotlinPoet, and later extract the KSP file when writing with [XFiler] if it
* exists.
*
* Note that this function doesn't yet support Kotlin top-level functions and properties from
* compiled classes in KSP due to https://github.com/google/ksp/issues/1704.
*/
internal fun XElement.originatingElementForPoet(): Element {
return if (this is JavacElement) {
element
} else {
// We use either the enclosing file or the class as the originating element for KSP.
this.closestMemberContainer.run {
when (this) {
is KspTypeElement -> {
declaration.wrapAsOriginatingElement()
}
is KspFileMemberContainer -> {
KSFileAsOriginatingElement(ksFile)
}
else -> {
error("Originating element is not implemented for" +
" ${this.javaClass}")
}
}
}
}
}