arrow.higherkinds.HigherKindsProcessor.kt Maven / Gradle / Ivy

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Functional companion to Kotlin's Standard Library

There is a newer version: 1.6.3-alpha.2

package arrow.higherkinds

import com.google.auto.service.AutoService
import arrow.common.utils.AbstractProcessor
import arrow.common.utils.knownError
import java.io.File
import javax.annotation.processing.Processor
import javax.annotation.processing.RoundEnvironment
import javax.lang.model.SourceVersion
import javax.lang.model.element.ElementKind
import javax.lang.model.element.TypeElement

@AutoService(Processor::class)
class HigherKindsProcessor : AbstractProcessor() {

  private val annotatedList: MutableList = mutableListOf()

  override fun getSupportedSourceVersion(): SourceVersion = SourceVersion.latestSupported()

  override fun getSupportedAnnotationTypes(): Set = setOf(higherKindsAnnotationClass.canonicalName)

  /**
   * Processor entry point
   */
  override fun onProcess(annotations: Set, roundEnv: RoundEnvironment) {
    annotatedList += roundEnv
      .getElementsAnnotatedWith(higherKindsAnnotationClass)
      .map { element ->
        when (element.kind) {
          ElementKind.CLASS -> processClass(element as TypeElement)
          ElementKind.INTERFACE -> processClass(element as TypeElement)
          else -> knownError("$higherKindsAnnotationName can only be used on classes")
        }
      }

    if (roundEnv.processingOver()) {
      val generatedDir = File(this.generatedDir!!, higherKindsAnnotationClass.simpleName).also { it.mkdirs() }
      HigherKindsFileGenerator(generatedDir, annotatedList).generate()
    }
  }

  private fun processClass(element: TypeElement): AnnotatedHigherKind {
    val proto = getClassOrPackageDataWrapper(element)
    return AnnotatedHigherKind(element, proto)
  }
}