Implement "Show non-public" filter for Kotlin structure view

#KT-14217 Fixed

idea/idea-analysis/src/org/jetbrains/kotlin/idea/structureView/KotlinStructureViewElement.kt

@@ -25,6 +25,8 @@ import com.intellij.psi.NavigatablePsiElement
 import com.intellij.psi.PsiElement
 import org.jetbrains.annotations.TestOnly
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptorWithVisibility
+import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptor
 import org.jetbrains.kotlin.idea.util.application.runReadAction
 import org.jetbrains.kotlin.psi.*
@@ -109,6 +111,9 @@ class KotlinStructureViewElement(val element: NavigatablePsiElement,
 
         return result
     }
+
+    val isPublic: Boolean
+        get() = (descriptor as? DeclarationDescriptorWithVisibility)?.visibility == Visibilities.PUBLIC
 }
 
 fun KtClassOrObject.getStructureDeclarations() = getPrimaryConstructorParameters().filter { it.hasValOrVar() } + declarations

idea/idea-analysis/src/org/jetbrains/kotlin/idea/structureView/KotlinStructureViewModel.kt

@@ -17,7 +17,8 @@
 package org.jetbrains.kotlin.idea.structureView
 
 import com.intellij.ide.structureView.StructureViewModelBase
-import com.intellij.ide.util.treeView.smartTree.Sorter
+import com.intellij.ide.util.treeView.smartTree.*
+import com.intellij.util.PlatformIcons
 import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.KtFile
 
@@ -30,7 +31,26 @@ class KotlinStructureViewModel(ktFile: KtFile) : StructureViewModelBase(ktFile,
 
     override fun getNodeProviders() = NODE_PROVIDERS
 
+    override fun getFilters() = FILTERS
+
     companion object {
         private val NODE_PROVIDERS = listOf(KotlinInheritedMembersNodeProvider())
+        private val FILTERS = arrayOf<Filter>(PublicElementsFilter)
     }
 }
+
+object PublicElementsFilter : Filter {
+    override fun isVisible(treeNode: TreeElement): Boolean {
+        return (treeNode as? KotlinStructureViewElement)?.isPublic ?: true
+    }
+
+    override fun getPresentation(): ActionPresentation {
+        return ActionPresentationData("Show non-public", null, PlatformIcons.PRIVATE_ICON)
+    }
+
+    override fun getName() = ID
+
+    override fun isReverted() = true
+
+    const val ID = "KOTLIN_SHOW_NON_PUBLIC"
+}