ru.kode.detekt.rule.compose.MissingModifierDefaultValue.kt Maven / Gradle / Ivy

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Detekt rules for Jetpack Compose

There is a newer version: 1.4.0

package ru.kode.detekt.rule.compose

import io.gitlab.arturbosch.detekt.api.CodeSmell
import io.gitlab.arturbosch.detekt.api.Config
import io.gitlab.arturbosch.detekt.api.Debt
import io.gitlab.arturbosch.detekt.api.Entity
import io.gitlab.arturbosch.detekt.api.Issue
import io.gitlab.arturbosch.detekt.api.Rule
import io.gitlab.arturbosch.detekt.api.Severity
import io.gitlab.arturbosch.detekt.rules.hasAnnotation
import io.gitlab.arturbosch.detekt.rules.isAbstract
import io.gitlab.arturbosch.detekt.rules.isOpen
import io.gitlab.arturbosch.detekt.rules.isOverride
import org.jetbrains.kotlin.psi.KtNamedFunction
import org.jetbrains.kotlin.psi.KtParameter
import org.jetbrains.kotlin.psi.psiUtil.containingClass
import ru.kode.detekt.rule.compose.node.isModifier

/**
 * Checks that the `modifier` parameter of a Composable function has a default value.
 *
 * Non-compliant:
 *
 * ```
 * fun Content(modifier: Modifier) {
 *   Text("Greetings")
 * }
 * ```
 *
 * Compliant:
 *
 * ```
 * fun Content(modifier: Modifier = Modifier) {
 *   Text("Greetings")
 * }
 * ```
 */
class MissingModifierDefaultValue(config: Config = Config.empty) : Rule(config) {
  override val issue = Issue(
    javaClass.simpleName,
    Severity.Defect,
    "Checks that Modifier parameter has a default value",
    Debt.FIVE_MINS
  )

  override fun visitNamedFunction(function: KtNamedFunction) {
    if (function.hasAnnotation("Composable")) {
      val modifierParameter = function.valueParameters.find { it.isModifier() }
      // abstract functions and interface functions cannot have default parameters
      // (Compose compiler plugin restriction).
      // Open methods do not have those restrictions, but it feels logical to exclude them too
      // in a similar manner
      if (function.isAbstract() || function.isOpen() || function.containingClass()?.isInterface() == true) {
        return
      }
      if (!function.isOverride() && modifierParameter?.hasDefaultValue() == false) {
        reportError(modifierParameter)
      }
    }
  }

  private fun reportError(node: KtParameter) {
    report(
      CodeSmell(
        issue,
        Entity.from(node),
        "Modifier parameter should have a default value: \"modifier = Modifier\""
      )
    )
  }
}