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

1 files changed, 39 insertions, 0 deletions

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
+