Lint for Kotlin @R.kt#3

Transcript

1. Lint For Kotlin
   TakuSemba
   CyberAgent.Inc
   

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

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

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4. ktlint
   ɾStatic code analysis tool for kotlin
   ɾBased on official code style
   ɾBuilt-in formatter
   ɾCustomizable output
   

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5. ktlint with gradle
   configurations {
   ktlint
   }
   dependencies {
   ktlint "com.github.shyiko:ktlint:$KTLINT_VERSION"
   }
   check.dependsOn ktlint
   

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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
   

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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
   

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

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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
   }
   

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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'
    

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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 “}"
    …
    

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12. Outputs
    --reporter=checkstyle
    
    
    
    line="25"
    column="7"
    severity="error"
    message="Line break before assignment is not allowed"
    source="no-line-break-before-assignment" />
    
    …
    
    

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

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

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15. Outputs
    class CustomReporterProvider : ReporterProvider {
    override val id: String = “custom-ktlint-reporter"
    override fun get(
    out: PrintStream,
    opt: Map
    ): Reporter = CustomReporter(out)
    }
    --reporter=custom-ktlint-rule
    

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16. Outputs
    class CustomReporterProvider : ReporterProvider {
    override val id: String = “custom-ktlint-reporter"
    override fun get(
    out: PrintStream,
    opt: Map
    ): Reporter = CustomReporter(out)
    }
    --reporter=custom-ktlint-rule
    ): Reporter = CustomReporter(out)
    

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

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18. Disable rules
    import package.* // ktlint-disable no-wildcard-imports
    import package.* // ktlint-disable
    disable specific rule
    disable the whole rule
    

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19. Disable rules
    

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

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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)
    }
    }
    }
    

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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,
    

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23. Abstract Syntax Tree
    

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

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25. node
    node node node
    node node node
    node
    node node
    AST
    

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

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

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28. AST
    { return a + b }
    KtKeywordToken.fun
    fun
    Int
    :
    (a: Int, b: Int)
    add KtToken.IDENTIFIER
    KtTypeReference
    KtSingleValueToken.COLON
    KtParameterList
    KtBlockExpression
    

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29. AST
    { return a + b }
    KtKeywordToken.fun
    fun
    Int
    :
    (a: Int, b: Int)
    add KtToken.IDENTIFIER
    KtTypeReference
    KtSingleValueToken.COLON
    KtParameterList
    KtBlockExpression
    

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

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

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

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33. node
    node node node
    node node node
    node
    node node
    AST
    

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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)
    }
    }
    }
    

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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,
    

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36. Add rules
    fun add(a: Int, b: Int): Int = a + b
    // OK
    fun add(a: Int, b: Int) = a + b
    // NG
    

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

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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)
    }
    }
    

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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')) {
    }
    

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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
    

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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) {
    =
    

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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)
    

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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)
    }
    }
    }
    }
    

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44. Add rules
    class CustomRuleSetProvider : RuleSetProvider {
    override fun get(): RuleSet = RuleSet(
    “custom-rule",
    ExpressionFunctionRule()
    )
    }
    

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45. Add rules
    class CustomRuleSetProvider : RuleSetProvider {
    override fun get(): RuleSet = RuleSet(
    “custom-rule",
    ExpressionFunctionRule()
    )
    }
    ExpressionFunctionRule()
    

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46. Add rules
    

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

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

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49. Add rules
    val rule = ExpressionFunctionRule()
    assertThat(rule.lint(
    """
    fun add(a: Int, b: Int): Int = a + b
    """
    .trimIndent())
    ).isEqualTo(emptyList())
    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())
    

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50. Add rules
    val rule = ExpressionFunctionRule()
    assertThat(rule.lint(
    """
    fun add(a: Int, b: Int): Int = a + b
    """
    .trimIndent())
    ).isEqualTo(emptyList())
    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!!!")))
    

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51. Add rules
    

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52. with Danger
    

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53. with Danger
    BQQTSDNBJOKBWBDPNUBLVTFNCB)PHFLU
    Danger
    # Dangerfile
    checkstyle_format.base_path = Dir.pwd
    checkstyle_format.report ‘path/to/result.xml’
    

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

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