/
UseEmptyCounterpart.kt
68 lines (61 loc) · 2.26 KB
/
UseEmptyCounterpart.kt
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package io.gitlab.arturbosch.detekt.rules.style
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.api.internal.RequiresTypeResolution
import org.jetbrains.kotlin.name.FqName
import org.jetbrains.kotlin.psi.KtCallExpression
import org.jetbrains.kotlin.resolve.calls.util.getResolvedCall
import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
/**
* Instantiation of an object's "empty" state should use the object's "empty" initializer for clarity purposes.
*
* <noncompliant>
* arrayOf()
* listOf() // or listOfNotNull()
* mapOf()
* sequenceOf()
* setOf()
* </noncompliant>
*
* <compliant>
* emptyArray()
* emptyList()
* emptyMap()
* emptySequence()
* emptySet()
* </compliant>
*
*/
@RequiresTypeResolution
class UseEmptyCounterpart(config: Config) : Rule(config) {
override val issue = Issue(
javaClass.simpleName,
Severity.Style,
"""Instantiation of an object's "empty" state should use the object's "empty" initializer.""",
Debt.FIVE_MINS
)
@Suppress("ReturnCount")
override fun visitCallExpression(expression: KtCallExpression) {
super.visitCallExpression(expression)
val resolvedCall = expression.getResolvedCall(bindingContext) ?: return
val fqName = resolvedCall.resultingDescriptor.fqNameOrNull() ?: return
val emptyCounterpart = exprsWithEmptyCounterparts[fqName] ?: return
if (expression.valueArguments.isEmpty()) {
val message = "${fqName.shortName()} can be replaced with $emptyCounterpart"
report(CodeSmell(issue, Entity.from(expression), message))
}
}
}
private val exprsWithEmptyCounterparts = mapOf(
FqName("kotlin.arrayOf") to "emptyArray",
FqName("kotlin.collections.listOf") to "emptyList",
FqName("kotlin.collections.listOfNotNull") to "emptyList",
FqName("kotlin.collections.mapOf") to "emptyMap",
FqName("kotlin.sequences.sequenceOf") to "emptySequence",
FqName("kotlin.collections.setOf") to "emptySet"
)