Create from usage: Support extension members for Java classes

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/resolve/JavaResolveExtension.kt

@@ -29,6 +29,15 @@ import org.jetbrains.kotlin.resolve.jvm.resolveMethod
 import org.jetbrains.kotlin.load.java.structure.impl.JavaMethodImpl
 import org.jetbrains.kotlin.load.java.structure.impl.JavaConstructorImpl
 import org.jetbrains.kotlin.resolve.jvm.resolveConstructor
+import com.intellij.psi.PsiClass
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.load.java.structure.impl.JavaClassImpl
+import com.intellij.psi.PsiField
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
+import org.jetbrains.kotlin.resolve.jvm.resolveField
+import org.jetbrains.kotlin.load.java.structure.impl.JavaFieldImpl
+import com.intellij.psi.PsiMember
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 
 public object JavaResolveExtension : CacheExtension<(PsiElement) -> Pair<JavaDescriptorResolver, BindingContext>> {
     override val platform: TargetPlatform = TargetPlatform.JVM
@@ -48,8 +57,6 @@ public object JavaResolveExtension : CacheExtension<(PsiElement) -> Pair<JavaDes
 }
 
 fun PsiMethod.getJavaMethodDescriptor(): FunctionDescriptor {
-    if (this is KotlinLightMethod) throw AssertionError("Light methods are not allowed here: ${getOrigin()?.getText()}")
-
     val resolver = JavaResolveExtension.getResolver(getProject(), this)
     val methodDescriptor = when {
         this.isConstructor() -> resolver.resolveConstructor(JavaConstructorImpl(this))
@@ -59,3 +66,28 @@ fun PsiMethod.getJavaMethodDescriptor(): FunctionDescriptor {
 
     return methodDescriptor!!
 }
+
+fun PsiClass.getJavaClassDescriptor(): ClassDescriptor {
+    val resolver = JavaResolveExtension.getResolver(getProject(), this)
+    val classDescriptor = resolver.resolveClass(JavaClassImpl(this))
+    assert(classDescriptor != null) { "No descriptor found for " + getText() }
+
+    return classDescriptor!!
+}
+
+fun PsiField.getJavaFieldDescriptor(): PropertyDescriptor {
+    val resolver = JavaResolveExtension.getResolver(getProject(), this)
+    val fieldDescriptor = resolver.resolveField(JavaFieldImpl(this))
+    assert(fieldDescriptor != null) { "No descriptor found for " + getText() }
+
+    return fieldDescriptor!!
+}
+
+fun PsiMember.getJavaMemberDescriptor(): DeclarationDescriptor? {
+    return when (this) {
+        is PsiClass -> getJavaClassDescriptor()
+        is PsiMethod -> getJavaMethodDescriptor()
+        is PsiField -> getJavaFieldDescriptor()
+        else -> null
+    }
+}