Lint for Kotlin @R.kt#3

Transcript

1. Lint For Kotlin TakuSemba CyberAgent.Inc

2. @takusemba https://github.com/TakuSemba

3. https://android.github.io/kotlin-guides/style.html

4. ktlint ɾStatic code analysis tool for kotlin ɾBased on official

   code style ɾBuilt-in formatter ɾCustomizable output

5. ktlint with gradle configurations { ktlint } dependencies { ktlint

   "com.github.shyiko:ktlint:$KTLINT_VERSION" } check.dependsOn ktlint

6. ktlint with gradle task ktlint(type: JavaExec, group: "kotlin verification") {

   description = 'Check Kotlin code style.' args 'src/**/*.kt' main = 'com.github.shyiko.ktlint.Main' classpath = configurations.ktlint + sourceSets.main.output } $ ./gradlew tasks

7. ktlint with gradle task ktFormat(type: JavaExec, group: "kotlin Formatting") {

   description = 'Fix Kotlin code style deviations.' args '-F', 'src/**/*.kt' main = 'com.github.shyiko.ktlint.Main' classpath = configurations.ktlint + sourceSets.main.output } $ ./gradlew tasks

8. ktlint with CLI $ brew install shyiko/ktlint/ktlint $ ktlint "src/**/*.kt"

9. Outputs task ktlint(type: JavaExec, dependsOn: classes) { description = 'Check

   Kotlin code style.' args 'src/**/*.kt', ‘--reporter=plain' main = 'com.github.shyiko.ktlint.Main' classpath = configurations.ktlint + sourceSets.main.output }

10. Outputs task ktlint(type: JavaExec, dependsOn: classes) { description = 'Check

    Kotlin code style.' args 'src/**/*.kt', ‘--reporter=plain' main = 'com.github.shyiko.ktlint.Main' classpath = configurations.ktlint + sourceSets.main.output } '--reporter=plain'

11. Outputs --reporter=plain takusemba/ktlint-sample/app/…/Hoge.kt:44:1: Unexpected blank line(s) before "}" takusemba/ktlint-sample/app/…/Fuga.kt:108:1: Needless

    blank line(s) takusemba/ktlint-sample/app/…/Foo.kt:25:7: Line break before assignment is not allowed takusemba/ktlint-sample/app/…/Bar.kt:47:1: Unexpected blank line(s) before “}" …

12. Outputs --reporter=checkstyle <?xml version="1.0" encoding="utf-8"?> <checkstyle version=“8.0"> <file name="takusemba/ktlint-sample/app/…/Hoge.kt"> <error

    line="25" column="7" severity="error" message="Line break before assignment is not allowed" source="no-line-break-before-assignment" /> </file> … </checkstyle>

13. Outputs --reporter=custom-ktlint-rule class CustomReporter(private val out: PrintStream) : Reporter {

    private val errors = ArrayList<LintError>() override fun onLintError( file: String, err: LintError, corrected: Boolean) { errors.add(err) } override fun afterAll() { out.println("hello custom reporter.") out.println("found ${errors.size} errors.") } }

14. Outputs --reporter=custom-ktlint-rule class CustomReporter(private val out: PrintStream) : Reporter {

    private val errors = ArrayList<LintError>() override fun onLintError( file: String, err: LintError, corrected: Boolean) { errors.add(err) } override fun afterAll() { out.println("hello custom reporter.") out.println("found ${errors.size} errors.") } } override fun afterAll() { out.println("hello custom reporter.") out.println("found ${errors.size} errors.") }

15. Outputs class CustomReporterProvider : ReporterProvider { override val id: String

    = “custom-ktlint-reporter" override fun get( out: PrintStream, opt: Map<String, String> ): Reporter = CustomReporter(out) } --reporter=custom-ktlint-rule

16. Outputs class CustomReporterProvider : ReporterProvider { override val id: String

    = “custom-ktlint-reporter" override fun get( out: PrintStream, opt: Map<String, String> ): Reporter = CustomReporter(out) } --reporter=custom-ktlint-rule ): Reporter = CustomReporter(out)

17. Outputs --reporter=custom-ktlint-rule

18. Disable rules import package.* // ktlint-disable no-wildcard-imports import package.* //

    ktlint-disable disable specific rule disable the whole rule

19. Disable rules

20. Disable rules [*.{kt,kts}] indent_size=2 continuation_indent_size=4 insert_final_newline=unset max_line_length=off .editorconfig

21. Add rules class CustomRule : Rule("custom-rule") { override fun visit(

    node: ASTNode, autoCorrect: Boolean, emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit ) { if (isLintError) { emit(node.startOffset, “LINT ERROR FOUND!”, false) } } }

22. Add rules class CustomRule : Rule("custom-rule") { override fun visit(

    node: ASTNode, autoCorrect: Boolean, emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit ) { if (isLintError) { emit(node.startOffset, “LINT ERROR FOUND!”, false) } } } node: ASTNode,

23. Abstract Syntax Tree

24. AST fun add(a: Int, b: Int): Int { return a

    + b }

25. node node node node node node node node node node

    AST

26. AST fun add(a: Int, b: Int): Int { return a

    + b }

27. AST fun add(a: Int, b: Int): Int { return a

    + b } KtNamedFunction

28. AST { return a + b } KtKeywordToken.fun fun Int

    : (a: Int, b: Int) add KtToken.IDENTIFIER KtTypeReference KtSingleValueToken.COLON KtParameterList KtBlockExpression

29. AST { return a + b } KtKeywordToken.fun fun Int

    : (a: Int, b: Int) add KtToken.IDENTIFIER KtTypeReference KtSingleValueToken.COLON KtParameterList KtBlockExpression

30. AST KtSingleValueToken.LBRACE KtReturnExpression KtSingleValueToken.RBRACE } { return a + b

31. AST KtSingleValueToken.LBRACE KtReturnExpression KtSingleValueToken.RBRACE } { return a + b

32. AST KtKeywordToken.return KtToken.IDENTIFIER KtSingleValueToken.PLUS a return + b KtToken.IDENTIFIER

33. node node node node node node node node node node

    AST

34. Add rules class CustomRule : Rule("custom-rule") { override fun visit(

    node: ASTNode, autoCorrect: Boolean, emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit ) { if (isLintError) { emit(node.startOffset, “LINT ERROR FOUND!”, false) } } }

35. Add rules class CustomRule : Rule("custom-rule") { override fun visit(

    node: ASTNode, autoCorrect: Boolean, emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit ) { if (isLintError) { emit(node.startOffset, “LINT ERROR FOUND!”, false) } } } node: ASTNode,

36. Add rules fun add(a: Int, b: Int): Int = a

    + b // OK fun add(a: Int, b: Int) = a + b // NG

37. fun add(a: Int, b: Int) = a + b //

    NG

38. Add rules fun add(a: Int, b: Int) = a +

    b // NG if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { emit(node.startOffset, "need return type!!!", false) } }

39. Add rules fun add(a: Int, b: Int) = a +

    b // NG if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { emit(node.startOffset, "need return type!!!", false) } } if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { }

40. Add rules fun add(a: Int, b: Int) = a +

    b // NG (a: Int, b: Int) if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { emit(node.startOffset, "need return type!!!”, false) } } val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return

41. Add rules fun add(a: Int, b: Int) = a +

    b // NG if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { emit(node.startOffset, "need return type!!!", false) } } if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { =

42. Add rules fun add(a: Int, b: Int) = a +

    b // NG if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { emit(node.startOffset, "need return type!!!", false) } } fun add(a: Int, b: Int) = a + b emit(node.startOffset, "need return type!!!", false)

43. Add rules class ExpressionFunctionRule : Rule("one-line-function") { override fun visit(

    node: ASTNode, autoCorrect: Boolean, emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit ) { if (node.elementType == KtStubElementTypes.FUNCTION && !node.text.contains('\n')) { val child = node.findChildByType(KtNodeTypes.VALUE_PARAMETER_LIST) ?: return if (child.treeNext.elementType == KtTokens.WHITE_SPACE && child.treeNext.treeNext.elementType == KtTokens.EQ) { emit(node.startOffset, "need return type!!!", false) } } } }

44. Add rules class CustomRuleSetProvider : RuleSetProvider { override fun get():

    RuleSet = RuleSet( “custom-rule", ExpressionFunctionRule() ) }

45. Add rules class CustomRuleSetProvider : RuleSetProvider { override fun get():

    RuleSet = RuleSet( “custom-rule", ExpressionFunctionRule() ) } ExpressionFunctionRule()

46. Add rules

47. Add rules $ ktlint "**/Hoge.kt" -R ktrule/build/libs/ktrule.jar --relative $ ./gradlew

    jar

48. Add rules val rule = ExpressionFunctionRule() assertThat(rule.lint( """ fun add(a:

    Int, b: Int): Int = a + b """ .trimIndent()) ).isEqualTo(emptyList<LintError>()) assertThat(rule.lint( """ fun add(a: Int, b: Int) = a + b """ .trimIndent()) ).isEqualTo(listOf(LintError(1, 1, "one-line-function", "need return type!!!")))

49. Add rules val rule = ExpressionFunctionRule() assertThat(rule.lint( """ fun add(a:

    Int, b: Int): Int = a + b """ .trimIndent()) ).isEqualTo(emptyList<LintError>()) assertThat(rule.lint( """ fun add(a: Int, b: Int) = a + b """ .trimIndent()) ).isEqualTo(listOf(LintError(1, 1, "one-line-function", "need return type!!!"))) val rule = ExpressionFunctionRule() assertThat(rule.lint( """ fun add(a: Int, b: Int): Int = a + b """ .trimIndent()) ).isEqualTo(emptyList<LintError>())

50. Add rules val rule = ExpressionFunctionRule() assertThat(rule.lint( """ fun add(a:

    Int, b: Int): Int = a + b """ .trimIndent()) ).isEqualTo(emptyList<LintError>()) assertThat(rule.lint( """ fun add(a: Int, b: Int) = a + b """ .trimIndent()) ).isEqualTo(listOf(LintError(1, 1, "one-line-function", "need return type!!!"))) assertThat(rule.lint( """ fun add(a: Int, b: Int) = a + b """ .trimIndent()) ).isEqualTo(listOf(LintError(1, 1, "one-line-function", "need return type!!!")))

51. Add rules

52. with Danger

53. with Danger BQQTSDNBJOKBWBDPNUBLVTFNCB)PHFLU Danger # Dangerfile checkstyle_format.base_path = Dir.pwd checkstyle_format.report

    ‘path/to/result.xml’

54. Lint For Kotlin https://github.com/takusemba https://twitter.com/takusemba