Add documentation for synthetic Enum `values()` and `valueOf()` functions (#2650)

9 files changed, 136 insertions, 12 deletions

diff --git a/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt b/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt
index c52fbd37..e3e1a33e 100644
--- a/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt
+++ b/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt
@@ -136,6 +136,7 @@ private class DokkaDescriptorVisitor(
     private val logger: DokkaLogger
 ) {
     private val javadocParser = JavadocParser(logger, resolutionFacade)
+    private val syntheticDocProvider = SyntheticDescriptorDocumentationProvider(resolutionFacade)
 
     private fun Collection<DeclarationDescriptor>.filterDescriptorsInSourceSet() = filter {
         it.toSourceElement.containingFile.toString().let { path ->
@@ -577,8 +578,7 @@ private class DokkaDescriptorVisitor(
                 sources = actual,
                 visibility = descriptor.visibility.toDokkaVisibility().toSourceSetDependent(),
                 generics = generics.await(),
-                documentation = descriptor.takeIf { it.kind != CallableMemberDescriptor.Kind.SYNTHESIZED }
-                    ?.resolveDescriptorData() ?: emptyMap(),
+                documentation = descriptor.getDocumentation(),
                 modifier = descriptor.modifier().toSourceSetDependent(),
                 type = descriptor.returnType!!.toBound(),
                 sourceSets = setOf(sourceSet),
@@ -594,6 +594,15 @@ private class DokkaDescriptorVisitor(
         }
     }
 
+    private fun FunctionDescriptor.getDocumentation(): SourceSetDependent<DocumentationNode> {
+        val isSynthesized = this.kind == CallableMemberDescriptor.Kind.SYNTHESIZED
+        return if (isSynthesized) {
+            syntheticDocProvider.getDocumentation(this)?.toSourceSetDependent() ?: emptyMap()
+        } else {
+            this.resolveDescriptorData()
+        }
+    }
+
     /**
      * `createDRI` returns the DRI of the exact element and potential DRI of an element that is overriding it
      * (It can be also FAKE_OVERRIDE which is in fact just inheritance of the symbol)
@@ -609,7 +618,7 @@ private class DokkaDescriptorVisitor(
 
     private fun FunctionDescriptor.isObvious(): Boolean {
         return kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE
-                || kind == CallableMemberDescriptor.Kind.SYNTHESIZED
+                || (kind == CallableMemberDescriptor.Kind.SYNTHESIZED && !syntheticDocProvider.isDocumented(this))
                 || containingDeclaration.fqNameOrNull()?.isObvious() == true
     }
 
diff --git a/plugins/base/src/main/kotlin/translators/descriptors/SyntheticDescriptorDocumentationProvider.kt b/plugins/base/src/main/kotlin/translators/descriptors/SyntheticDescriptorDocumentationProvider.kt
new file mode 100644
index 00000000..c96b888a
--- /dev/null
+++ b/plugins/base/src/main/kotlin/translators/descriptors/SyntheticDescriptorDocumentationProvider.kt
@@ -0,0 +1,47 @@
+package org.jetbrains.dokka.base.translators.descriptors
+
+import org.jetbrains.dokka.analysis.DokkaResolutionFacade
+import org.jetbrains.dokka.analysis.from
+import org.jetbrains.dokka.base.parsers.MarkdownParser
+import org.jetbrains.dokka.links.DRI
+import org.jetbrains.dokka.model.doc.DocumentationNode
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.idea.kdoc.resolveKDocLink
+import org.jetbrains.kotlin.resolve.DescriptorFactory
+
+private const val ENUM_VALUEOF_TEMPLATE_PATH = "/dokka/docs/kdoc/EnumValueOf.kt.template"
+private const val ENUM_VALUES_TEMPLATE_PATH = "/dokka/docs/kdoc/EnumValues.kt.template"
+
+ internal class SyntheticDescriptorDocumentationProvider(
+    private val resolutionFacade: DokkaResolutionFacade
+) {
+    fun isDocumented(descriptor: DeclarationDescriptor): Boolean = descriptor is FunctionDescriptor
+            && (DescriptorFactory.isEnumValuesMethod(descriptor) || DescriptorFactory.isEnumValueOfMethod(descriptor))
+
+    fun getDocumentation(descriptor: DeclarationDescriptor): DocumentationNode? {
+        val function = descriptor as? FunctionDescriptor ?: return null
+        return when {
+            DescriptorFactory.isEnumValuesMethod(function) -> loadTemplate(descriptor, ENUM_VALUES_TEMPLATE_PATH)
+            DescriptorFactory.isEnumValueOfMethod(function) -> loadTemplate(descriptor, ENUM_VALUEOF_TEMPLATE_PATH)
+            else -> null
+        }
+    }
+
+    private fun loadTemplate(descriptor: DeclarationDescriptor, filePath: String): DocumentationNode? {
+        val kdoc = loadContent(filePath) ?: return null
+        val parser = MarkdownParser({ link -> resolveLink(descriptor, link)}, filePath)
+        return parser.parse(kdoc)
+    }
+
+    private fun loadContent(filePath: String): String? = javaClass.getResource(filePath)?.readText()
+
+    private fun resolveLink(descriptor: DeclarationDescriptor, link: String): DRI? =
+        resolveKDocLink(
+            resolutionFacade.resolveSession.bindingContext,
+            resolutionFacade,
+            descriptor,
+            null,
+            link.split('.')
+        ).firstOrNull()?.let { DRI.from(it) }
+}
diff --git a/plugins/base/src/main/kotlin/translators/psi/DefaultPsiToDocumentableTranslator.kt b/plugins/base/src/main/kotlin/translators/psi/DefaultPsiToDocumentableTranslator.kt
index 58524479..574fb2e8 100644
--- a/plugins/base/src/main/kotlin/translators/psi/DefaultPsiToDocumentableTranslator.kt
+++ b/plugins/base/src/main/kotlin/translators/psi/DefaultPsiToDocumentableTranslator.kt
@@ -8,8 +8,6 @@ import com.intellij.lang.jvm.annotation.JvmAnnotationEnumFieldValue
 import com.intellij.lang.jvm.types.JvmReferenceType
 import com.intellij.openapi.vfs.VirtualFileManager
 import com.intellij.psi.*
-import com.intellij.psi.impl.source.PsiClassReferenceType
-import com.intellij.psi.impl.source.PsiImmediateClassType
 import kotlinx.coroutines.async
 import kotlinx.coroutines.coroutineScope
 import org.jetbrains.dokka.DokkaConfiguration.DokkaSourceSet
@@ -99,8 +97,8 @@ class DefaultPsiToDocumentableTranslator(
         facade: DokkaResolutionFacade,
         private val logger: DokkaLogger
     ) {
-
-        private val javadocParser: JavaDocumentationParser = JavadocParser(logger, facade)
+        private val javadocParser = JavadocParser(logger, facade)
+        private val syntheticDocProvider = SyntheticElementDocumentationProvider(javadocParser, facade)
 
         private val cachedBounds = hashMapOf<String, Bound>()
 
@@ -404,7 +402,7 @@ class DefaultPsiToDocumentableTranslator(
             val dri = parentDRI?.let { dri ->
                 DRI.from(psi).copy(packageName = dri.packageName, classNames = dri.classNames)
             } ?: DRI.from(psi)
-            val docs = javadocParser.parseDocumentation(psi)
+            val docs = psi.getDocumentation()
             return DFunction(
                 dri = dri,
                 name = psi.name,
@@ -452,8 +450,13 @@ class DefaultPsiToDocumentableTranslator(
             )
         }
 
+        private fun PsiMethod.getDocumentation(): DocumentationNode =
+            this.takeIf { it is SyntheticElement }?.let { syntheticDocProvider.getDocumentation(it) }
+                ?: javadocParser.parseDocumentation(this)
+
         private fun PsiMethod.isObvious(inheritedFrom: DRI? = null): Boolean {
-            return this is SyntheticElement || inheritedFrom?.isObvious() == true
+            return (this is SyntheticElement && !syntheticDocProvider.isDocumented(this))
+                    || inheritedFrom?.isObvious() == true
         }
 
         private fun DRI.isObvious(): Boolean {
diff --git a/plugins/base/src/main/kotlin/translators/psi/SynheticElementDocumentationProvider.kt b/plugins/base/src/main/kotlin/translators/psi/SynheticElementDocumentationProvider.kt
new file mode 100644
index 00000000..376c0940
--- /dev/null
+++ b/plugins/base/src/main/kotlin/translators/psi/SynheticElementDocumentationProvider.kt
@@ -0,0 +1,39 @@
+package org.jetbrains.dokka.base.translators.psi
+
+import com.intellij.psi.*
+import com.intellij.psi.javadoc.PsiDocComment
+import org.jetbrains.dokka.analysis.DokkaResolutionFacade
+import org.jetbrains.dokka.base.translators.psi.parsers.JavadocParser
+import org.jetbrains.dokka.model.doc.DocumentationNode
+
+private const val ENUM_VALUEOF_TEMPLATE_PATH = "/dokka/docs/javadoc/EnumValueOf.java.template"
+private const val ENUM_VALUES_TEMPLATE_PATH = "/dokka/docs/javadoc/EnumValues.java.template"
+
+internal class SyntheticElementDocumentationProvider(
+    private val javadocParser: JavadocParser,
+    private val resolutionFacade: DokkaResolutionFacade
+) {
+    fun isDocumented(psiElement: PsiElement): Boolean = psiElement is PsiMethod
+            && (psiElement.isSyntheticEnumValuesMethod() || psiElement.isSyntheticEnumValueOfMethod())
+
+    fun getDocumentation(psiElement: PsiElement): DocumentationNode? {
+        val psiMethod = psiElement as? PsiMethod ?: return null
+        val templatePath = when {
+            psiMethod.isSyntheticEnumValuesMethod() -> ENUM_VALUES_TEMPLATE_PATH
+            psiMethod.isSyntheticEnumValueOfMethod() -> ENUM_VALUEOF_TEMPLATE_PATH
+            else -> return null
+        }
+        val docComment = loadSyntheticDoc(templatePath) ?: return null
+        return javadocParser.parseDocComment(docComment, psiElement)
+    }
+
+    private fun loadSyntheticDoc(path: String): PsiDocComment? {
+        val text = javaClass.getResource(path)?.readText() ?: return null
+        return JavaPsiFacade.getElementFactory(resolutionFacade.project).createDocCommentFromText(text)
+    }
+}
+
+private fun PsiMethod.isSyntheticEnumValuesMethod() = this.isSyntheticEnumFunction() && this.name == "values"
+private fun PsiMethod.isSyntheticEnumValueOfMethod() = this.isSyntheticEnumFunction() && this.name == "valueOf"
+private fun PsiMethod.isSyntheticEnumFunction() = this is SyntheticElement && this.containingClass?.isEnum == true
+
diff --git a/plugins/base/src/main/kotlin/translators/psi/parsers/JavadocParser.kt b/plugins/base/src/main/kotlin/translators/psi/parsers/JavadocParser.kt
index 076d43a2..6a39652a 100644
--- a/plugins/base/src/main/kotlin/translators/psi/parsers/JavadocParser.kt
+++ b/plugins/base/src/main/kotlin/translators/psi/parsers/JavadocParser.kt
@@ -50,14 +50,13 @@ class JavadocParser(
 
     override fun parseDocumentation(element: PsiNamedElement): DocumentationNode {
         return when(val comment = findClosestDocComment(element, logger)){
-            is JavaDocComment -> parseDocumentation(comment, element)
+            is JavaDocComment -> parseDocComment(comment.comment, element)
             is KotlinDocComment -> parseDocumentation(comment)
             else -> DocumentationNode(emptyList())
         }
     }
 
-    private fun parseDocumentation(element: JavaDocComment, context: PsiNamedElement): DocumentationNode {
-        val docComment = element.comment
+    internal fun parseDocComment(docComment: PsiDocComment, context: PsiNamedElement): DocumentationNode {
         val nodes = listOfNotNull(docComment.getDescription()) + docComment.tags.mapNotNull { tag ->
             parseDocTag(tag, docComment, context)
         }
diff --git a/plugins/base/src/main/resources/dokka/docs/javadoc/EnumValueOf.java.template b/plugins/base/src/main/resources/dokka/docs/javadoc/EnumValueOf.java.template
new file mode 100644
index 00000000..233f8819
--- /dev/null
+++ b/plugins/base/src/main/resources/dokka/docs/javadoc/EnumValueOf.java.template
@@ -0,0 +1,12 @@
+/**
+ * Returns the enum constant of this type with the specified
+ * name.
+ * The string must match exactly an identifier used to declare
+ * an enum constant in this type.  (Extraneous whitespace
+ * characters are not permitted.)
+ *
+ * @return the enum constant with the specified name
+ * @throws IllegalArgumentException if this enum type has no
+ * constant with the specified name
+ */
+ 
\ No newline at end of file
diff --git a/plugins/base/src/main/resources/dokka/docs/javadoc/EnumValues.java.template b/plugins/base/src/main/resources/dokka/docs/javadoc/EnumValues.java.template
new file mode 100644
index 00000000..4aed38a6
--- /dev/null
+++ b/plugins/base/src/main/resources/dokka/docs/javadoc/EnumValues.java.template
@@ -0,0 +1,8 @@
+/**
+ * Returns an array containing the constants of this enum
+ * type, in the order they're declared.  This method may be
+ * used to iterate over the constants.
+ *
+ * @return an array containing the constants of this enum
+ * type, in the order they're declared
+ */
diff --git a/plugins/base/src/main/resources/dokka/docs/kdoc/EnumValueOf.kt.template b/plugins/base/src/main/resources/dokka/docs/kdoc/EnumValueOf.kt.template
new file mode 100644
index 00000000..fbf8fa8d
--- /dev/null
+++ b/plugins/base/src/main/resources/dokka/docs/kdoc/EnumValueOf.kt.template
@@ -0,0 +1,4 @@
+Returns the enum constant of this type with the specified name. The string must match exactly an identifier used
+to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
+
+@throws kotlin.IllegalArgumentException if this enum type has no constant with the specified name
diff --git a/plugins/base/src/main/resources/dokka/docs/kdoc/EnumValues.kt.template b/plugins/base/src/main/resources/dokka/docs/kdoc/EnumValues.kt.template
new file mode 100644
index 00000000..c0e3559c
--- /dev/null
+++ b/plugins/base/src/main/resources/dokka/docs/kdoc/EnumValues.kt.template
@@ -0,0 +1,3 @@
+Returns an array containing the constants of this enum type, in the order they're declared.
+
+This method may be used to iterate over the constants.