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fix: don't remove arrow from lambdas that are when/if leaf nodes #2758

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merged 2 commits into from
Aug 6, 2024
Merged

fix: don't remove arrow from lambdas that are when/if leaf nodes #2758

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e6c4930
fix: don't remove arrow from lamdas thare are when/if leaf nodes
tKe Aug 1, 2024
dd012b9
Refactor
paul-dingemans Aug 6, 2024
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30 changes: 29 additions & 1 deletion ...andard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRule.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -4,13 +4,16 @@ import com.pinterest.ktlint.logger.api.initKtLintKLogger
import com.pinterest.ktlint.rule.engine.core.api.AutocorrectDecision
import com.pinterest.ktlint.rule.engine.core.api.ElementType.ARROW
import com.pinterest.ktlint.rule.engine.core.api.ElementType.BLOCK
import com.pinterest.ktlint.rule.engine.core.api.ElementType.ELSE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.FUNCTION_LITERAL
import com.pinterest.ktlint.rule.engine.core.api.ElementType.LAMBDA_ARGUMENT
import com.pinterest.ktlint.rule.engine.core.api.ElementType.LAMBDA_EXPRESSION
import com.pinterest.ktlint.rule.engine.core.api.ElementType.LBRACE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.RBRACE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.THEN
import com.pinterest.ktlint.rule.engine.core.api.ElementType.VALUE_PARAMETER
import com.pinterest.ktlint.rule.engine.core.api.ElementType.VALUE_PARAMETER_LIST
import com.pinterest.ktlint.rule.engine.core.api.ElementType.WHEN_ENTRY
import com.pinterest.ktlint.rule.engine.core.api.IndentConfig
import com.pinterest.ktlint.rule.engine.core.api.Rule.VisitorModifier.RunAfterRule.Mode.REGARDLESS_WHETHER_RUN_AFTER_RULE_IS_LOADED_OR_DISABLED
import com.pinterest.ktlint.rule.engine.core.api.RuleId
Expand Down Expand Up @@ -366,7 +369,9 @@ public class FunctionLiteralRule :
require(arrow.elementType == ARROW)
arrow
.prevSibling { it.elementType == VALUE_PARAMETER_LIST }
?.takeIf { it.findChildByType(VALUE_PARAMETER) == null && arrow.isFollowedByNonEmptyBlock() }
?.takeIf { it.hasEmptyParameterList() }
?.takeUnless { arrow.isLambdaExpressionNotWrappedInBlock() }
?.takeIf { arrow.isFollowedByNonEmptyBlock() }
?.let {
emit(arrow.startOffset, "Arrow is redundant when parameter list is empty", true)
.ifAutocorrectAllowed {
Expand All @@ -379,6 +384,29 @@ public class FunctionLiteralRule :
}
}

private fun ASTNode.hasEmptyParameterList(): Boolean {
require(elementType == VALUE_PARAMETER_LIST)
return findChildByType(VALUE_PARAMETER) == null
}

private fun ASTNode.isLambdaExpressionNotWrappedInBlock(): Boolean {
require(elementType == ARROW)
return parent(LAMBDA_EXPRESSION)
?.treeParent
?.elementType
?.let { parentElementType ->
// Allow:
// val foo = when {
// 1 == 2 -> { -> "hi" }
// else -> { -> "ho" }
// }
// or
// val foo = if (cond) { -> "hi" } else { -> "ho" } parent ->
parentElementType == WHEN_ENTRY || parentElementType == THEN || parentElementType == ELSE
}
?: false
}

private fun ASTNode.isFollowedByNonEmptyBlock(): Boolean {
require(elementType == ARROW)
return nextSibling { it.elementType == BLOCK }?.firstChildNode != null
Expand Down
72 changes: 72 additions & 0 deletions ...rd/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRuleTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -506,4 +506,76 @@ class FunctionLiteralRuleTest {
""".trimIndent()
functionLiteralRuleAssertThat(code).hasNoLintViolations()
}

@Test
fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal as leaf of when then do not remove the arrow`() {
val code =
"""
val foo =
when {
false -> { -> "bar" }
else -> { -> "baz" }
}
""".trimIndent()
functionLiteralRuleAssertThat(code).hasNoLintViolations()
}

@Test
fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal not as leaf of when then do remove the arrow`() {
val code =
"""
val foo =
when {
false -> { { -> "bar" } }
else -> { { -> "baz" } }
}
""".trimIndent()
val formattedCode =
"""
val foo =
when {
false -> { { "bar" } }
else -> { { "baz" } }
}
""".trimIndent()
functionLiteralRuleAssertThat(code)
.hasLintViolations(
LintViolation(3, 22, "Arrow is redundant when parameter list is empty"),
LintViolation(4, 21, "Arrow is redundant when parameter list is empty"),
).isFormattedAs(formattedCode)
}

@Test
fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal as leaf of if then do not remove the arrow`() {
val code =
"""
val foo = if (cond) { -> "bar" } else { -> "baz" }
""".trimIndent()
functionLiteralRuleAssertThat(code).hasNoLintViolations()
}

@Test
fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal not as leaf of if then do remove the arrow`() {
val code =
"""
val foo = if (cond) {
{ -> "bar" }
} else {
{ -> "baz" }
}
""".trimIndent()
val formattedCode =
"""
val foo = if (cond) {
{ "bar" }
} else {
{ "baz" }
}
""".trimIndent()
functionLiteralRuleAssertThat(code)
.hasLintViolations(
LintViolation(2, 7, "Arrow is redundant when parameter list is empty"),
LintViolation(4, 7, "Arrow is redundant when parameter list is empty"),
).isFormattedAs(formattedCode)
}
}