Codegen for parcelable/dataclass boilerplate

This is the initial implementation of the `codegen` cli utility
for in-place java boilerplate generation

See DataClass and SampleDataClass for documentation/guide/examples.

See tools/codegen/ for implementation and tests/Codegen/ for tests.

Bug: 64221737
Test: . frameworks/base/tests/Codegen/runTest.sh
Change-Id: I75177cb770f1beabc87dbae9e77ce4b93ca08e7f
diff --git a/tools/codegen/.gitignore b/tools/codegen/.gitignore
new file mode 100755
index 0000000..9fb18b4
--- /dev/null
+++ b/tools/codegen/.gitignore
@@ -0,0 +1,2 @@
+.idea
+out
diff --git a/tools/codegen/Android.bp b/tools/codegen/Android.bp
new file mode 100644
index 0000000..805b296
--- /dev/null
+++ b/tools/codegen/Android.bp
@@ -0,0 +1,18 @@
+java_binary_host {
+    name: "codegen",
+    manifest: "manifest.txt",
+    srcs: [
+        "src/**/*.kt",
+    ],
+    static_libs: [
+        "javaparser",
+    ],
+}
+
+java_library_host {
+    name: "codegen-version-info",
+
+    srcs: [
+        "src/**/SharedConstants.kt",
+    ],
+}
diff --git a/tools/codegen/OWNERS b/tools/codegen/OWNERS
new file mode 100644
index 0000000..da723b3
--- /dev/null
+++ b/tools/codegen/OWNERS
@@ -0,0 +1 @@
+eugenesusla@google.com
\ No newline at end of file
diff --git a/tools/codegen/manifest.txt b/tools/codegen/manifest.txt
new file mode 100644
index 0000000..6e1018b
--- /dev/null
+++ b/tools/codegen/manifest.txt
@@ -0,0 +1 @@
+Main-class: com.android.codegen.MainKt
diff --git a/tools/codegen/src/com/android/codegen/ClassInfo.kt b/tools/codegen/src/com/android/codegen/ClassInfo.kt
new file mode 100644
index 0000000..7ee79f6
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/ClassInfo.kt
@@ -0,0 +1,49 @@
+package com.android.codegen
+
+import com.github.javaparser.JavaParser
+import com.github.javaparser.ParseProblemException
+import com.github.javaparser.ast.body.ClassOrInterfaceDeclaration
+
+open class ClassInfo(val sourceLines: List<String>) {
+
+    private val userSourceCode = (sourceLines + "}").joinToString("\n")
+    val fileAst = try {
+        JavaParser.parse(userSourceCode)!!
+    } catch (e: ParseProblemException) {
+        throw RuntimeException("Failed to parse code:\n" +
+                userSourceCode
+                        .lines()
+                        .mapIndexed { lnNum, ln -> "/*$lnNum*/$ln" }
+                        .joinToString("\n"),
+                e)
+    }
+    val classAst = fileAst.types[0] as ClassOrInterfaceDeclaration
+
+    fun hasMethod(name: String, vararg argTypes: String): Boolean {
+        return classAst.methods.any {
+            it.name.asString() == name &&
+                    it.parameters.map { it.type.asString() } == argTypes.toList()
+        }
+    }
+
+    val superInterfaces = (fileAst.types[0] as ClassOrInterfaceDeclaration)
+            .implementedTypes.map { it.asString() }
+
+    val ClassName = classAst.nameAsString
+    private val genericArgsAst = classAst.typeParameters
+    val genericArgs = if (genericArgsAst.isEmpty()) "" else {
+        genericArgsAst.map { it.nameAsString }.joinToString(", ").let { "<$it>" }
+    }
+    val ClassType = ClassName + genericArgs
+
+    val constDefs = mutableListOf<ConstDef>()
+
+    val fields = classAst.fields
+            .filterNot { it.isTransient || it.isStatic }
+            .mapIndexed { i, node -> FieldInfo(index = i, fieldAst = node, classInfo = this) }
+            .apply { lastOrNull()?.isLast = true }
+    val lazyTransientFields = classAst.fields
+            .filter { it.isTransient && !it.isStatic }
+            .mapIndexed { i, node -> FieldInfo(index = i, fieldAst = node, classInfo = this) }
+            .filter { hasMethod("lazyInit${it.NameUpperCamel}") }
+}
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/ClassPrinter.kt b/tools/codegen/src/com/android/codegen/ClassPrinter.kt
new file mode 100644
index 0000000..33256b7
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/ClassPrinter.kt
@@ -0,0 +1,311 @@
+package com.android.codegen
+
+import com.github.javaparser.ast.body.ClassOrInterfaceDeclaration
+import com.github.javaparser.ast.body.TypeDeclaration
+import com.github.javaparser.ast.expr.BooleanLiteralExpr
+import com.github.javaparser.ast.expr.NormalAnnotationExpr
+import com.github.javaparser.ast.type.ClassOrInterfaceType
+
+/**
+ * [ClassInfo] + utilities for printing out new class code with proper indentation and imports
+ */
+class ClassPrinter(
+    source: List<String>,
+    private val stringBuilder: StringBuilder,
+    var cliArgs: Array<String>
+) : ClassInfo(source) {
+
+    val GENERATED_MEMBER_HEADER by lazy { "@$GeneratedMember" }
+
+    // Imports
+    val NonNull by lazy { classRef("android.annotation.NonNull") }
+    val NonEmpty by lazy { classRef("android.annotation.NonEmpty") }
+    val Nullable by lazy { classRef("android.annotation.Nullable") }
+    val TextUtils by lazy { classRef("android.text.TextUtils") }
+    val LinkedHashMap by lazy { classRef("java.util.LinkedHashMap") }
+    val Collections by lazy { classRef("java.util.Collections") }
+    val Preconditions by lazy { classRef("com.android.internal.util.Preconditions") }
+    val ArrayList by lazy { classRef("java.util.ArrayList") }
+    val DataClass by lazy { classRef("com.android.internal.util.DataClass") }
+    val DataClassEnum by lazy { classRef("com.android.internal.util.DataClass.Enum") }
+    val ParcelWith by lazy { classRef("com.android.internal.util.DataClass.ParcelWith") }
+    val PluralOf by lazy { classRef("com.android.internal.util.DataClass.PluralOf") }
+    val Each by lazy { classRef("com.android.internal.util.DataClass.Each") }
+    val DataClassGenerated by lazy { classRef("com.android.internal.util.DataClass.Generated") }
+    val GeneratedMember by lazy { classRef("com.android.internal.util.DataClass.Generated.Member") }
+    val Parcelling by lazy { classRef("com.android.internal.util.Parcelling") }
+    val UnsupportedAppUsage by lazy { classRef("android.annotation.UnsupportedAppUsage") }
+
+
+    /**
+     * Optionally shortens a class reference if there's a corresponding import present
+     */
+    fun classRef(fullName: String): String {
+        if (cliArgs.contains(FLAG_NO_FULL_QUALIFIERS)) {
+            return fullName.split(".").dropWhile { it[0].isLowerCase() }.joinToString(".")
+        }
+
+        val pkg = fullName.substringBeforeLast(".")
+        val simpleName = fullName.substringAfterLast(".")
+        if (fileAst.imports.any { imprt ->
+                    imprt.nameAsString == fullName
+                            || (imprt.isAsterisk && imprt.nameAsString == pkg)
+                }) {
+            return simpleName
+        } else {
+            val outerClass = pkg.substringAfterLast(".", "")
+            if (outerClass.firstOrNull()?.isUpperCase() ?: false) {
+                return classRef(pkg) + "." + simpleName
+            }
+        }
+        return fullName
+    }
+
+    /** @see classRef */
+    inline fun <reified T : Any> classRef(): String {
+        return classRef(T::class.java.name)
+    }
+
+    /** @see classRef */
+    fun memberRef(fullName: String): String {
+        val className = fullName.substringBeforeLast(".")
+        val methodName = fullName.substringAfterLast(".")
+        return if (fileAst.imports.any {
+                    it.isStatic
+                            && (it.nameAsString == fullName
+                            || (it.isAsterisk && it.nameAsString == className))
+                }) {
+            className.substringAfterLast(".") + "." + methodName
+        } else {
+            classRef(className) + "." + methodName
+        }
+    }
+
+    val dataClassAnnotationFeatures = classAst.annotations
+            .find { it.nameAsString == DataClass }
+            ?.let { it as? NormalAnnotationExpr }
+            ?.pairs
+            ?.map { pair -> pair.nameAsString to (pair.value as BooleanLiteralExpr).value }
+            ?.toMap()
+            ?: emptyMap()
+
+    val internalAnnotations = setOf(ParcelWith, DataClassEnum, PluralOf, Each, UnsupportedAppUsage)
+
+    /**
+     * @return whether the given feature is enabled
+     */
+    operator fun FeatureFlag.invoke(): Boolean {
+        if (cliArgs.contains("--no-$kebabCase")) return false
+        if (cliArgs.contains("--$kebabCase")) return true
+
+        val annotationKey = "gen$upperCamelCase"
+        if (dataClassAnnotationFeatures.containsKey(annotationKey)) {
+            return dataClassAnnotationFeatures[annotationKey]!!
+        }
+
+        if (cliArgs.contains("--all")) return true
+        if (hidden) return true
+
+        return when (this) {
+            FeatureFlag.SETTERS ->
+                !FeatureFlag.CONSTRUCTOR() && !FeatureFlag.BUILDER() && fields.any { !it.isFinal }
+            FeatureFlag.BUILDER -> cliArgs.contains(FLAG_BUILDER_PROTECTED_SETTERS) || onByDefault
+            FeatureFlag.CONSTRUCTOR -> !FeatureFlag.BUILDER()
+            FeatureFlag.PARCELABLE -> "Parcelable" in superInterfaces
+            FeatureFlag.AIDL -> FeatureFlag.PARCELABLE()
+            FeatureFlag.IMPLICIT_NONNULL -> fields.any { it.isNullable }
+                    && fields.none { "@$NonNull" in it.annotations }
+            else -> onByDefault
+        }
+    }
+
+    val FeatureFlag.hidden
+        get(): Boolean = when {
+            cliArgs.contains("--hidden-$kebabCase") -> true
+            this == FeatureFlag.BUILD_UPON -> FeatureFlag.BUILDER.hidden
+            else -> false
+        }
+
+    var currentIndent = INDENT_SINGLE
+        private set
+
+    fun pushIndent() {
+        currentIndent += INDENT_SINGLE
+    }
+
+    fun popIndent() {
+        currentIndent = currentIndent.substring(0, currentIndent.length - INDENT_SINGLE.length)
+    }
+
+    fun backspace() = stringBuilder.setLength(stringBuilder.length - 1)
+    val lastChar get() = stringBuilder[stringBuilder.length - 1]
+
+    private fun appendRaw(s: String) {
+        stringBuilder.append(s)
+    }
+
+    fun append(s: String) {
+        if (s.isBlank() && s != "\n") {
+            appendRaw(s)
+        } else {
+            appendRaw(s.lines().map { line ->
+                if (line.startsWith(" *")) line else line.trimStart()
+            }.joinToString("\n$currentIndent"))
+        }
+    }
+
+    fun appendSameLine(s: String) {
+        while (lastChar.isWhitespace() || lastChar.isNewline()) {
+            backspace()
+        }
+        appendRaw(s)
+    }
+
+    fun rmEmptyLine() {
+        while (lastChar.isWhitespaceNonNewline()) backspace()
+        if (lastChar.isNewline()) backspace()
+    }
+
+    /**
+     * Syntactic sugar for:
+     * ```
+     * +"code()";
+     * ```
+     * to append the given string plus a newline
+     */
+    operator fun String.unaryPlus() = append("$this\n")
+
+    /**
+     * Syntactic sugar for:
+     * ```
+     * !"code()";
+     * ```
+     * to append the given string without a newline
+     */
+    operator fun String.not() = append(this)
+
+    /**
+     * Syntactic sugar for:
+     * ```
+     * ... {
+     *     ...
+     * }+";"
+     * ```
+     * to append a ';' on same line after a block, and a newline afterwards
+     */
+    operator fun Unit.plus(s: String) {
+        appendSameLine(s)
+        +""
+    }
+
+    /**
+     * A multi-purpose syntactic sugar for appending the given string plus anything generated in
+     * the given [block], the latter with the appropriate deeper indent,
+     * and resetting the indent back to original at the end
+     *
+     * Usage examples:
+     *
+     * ```
+     * "if (...)" {
+     *     ...
+     * }
+     * ```
+     * to append a corresponding if block appropriate indentation
+     *
+     * ```
+     * "void foo(...)" {
+     *      ...
+     * }
+     * ```
+     * similar to the previous one, plus an extra empty line after the function body
+     *
+     * ```
+     * "void foo(" {
+     *      <args code>
+     * }
+     * ```
+     * to use proper indentation for args code and close the bracket on same line at end
+     *
+     * ```
+     * "..." {
+     *     ...
+     * }
+     * to use the correct indentation for inner code, resetting it at the end
+     */
+    inline operator fun String.invoke(block: ClassPrinter.() -> Unit) {
+        if (this == " {") {
+            appendSameLine(this)
+        } else {
+            append(this)
+        }
+        when {
+            endsWith("(") -> {
+                indentedBy(2, block)
+                appendSameLine(")")
+            }
+            endsWith("{") || endsWith(")") -> {
+                if (!endsWith("{")) appendSameLine(" {")
+                indentedBy(1, block)
+                +"}"
+                if ((endsWith(") {") || endsWith(")") || this == " {")
+                        && !startsWith("synchronized")
+                        && !startsWith("switch")
+                        && !startsWith("if ")
+                        && !contains(" else ")
+                        && !contains("new ")
+                        && !contains("return ")) {
+                    +"" // extra line after function definitions
+                }
+            }
+            else -> indentedBy(2, block)
+        }
+    }
+
+    inline fun indentedBy(level: Int, block: ClassPrinter.() -> Unit) {
+        append("\n")
+        level times {
+            append(INDENT_SINGLE)
+            pushIndent()
+        }
+        block()
+        level times { popIndent() }
+        rmEmptyLine()
+        +""
+    }
+
+    inline fun Iterable<FieldInfo>.forEachTrimmingTrailingComma(b: FieldInfo.() -> Unit) {
+        forEachApply {
+            b()
+            if (isLast) {
+                while (lastChar == ' ' || lastChar == '\n') backspace()
+                if (lastChar == ',') backspace()
+            }
+        }
+    }
+
+    inline operator fun <R> invoke(f: ClassPrinter.() -> R): R = run(f)
+
+    var BuilderClass = CANONICAL_BUILDER_CLASS
+    var BuilderType = BuilderClass + genericArgs
+
+    init {
+        val builderFactoryOverride = classAst.methods.find {
+            it.isStatic && it.nameAsString == "builder"
+        }
+        if (builderFactoryOverride != null) {
+            BuilderClass = (builderFactoryOverride.type as ClassOrInterfaceType).nameAsString
+            BuilderType = builderFactoryOverride.type.asString()
+        } else {
+            val builderExtension = (fileAst.types
+                    + classAst.childNodes.filterIsInstance(TypeDeclaration::class.java)).find {
+                it.nameAsString == CANONICAL_BUILDER_CLASS
+            }
+            if (builderExtension != null) {
+                BuilderClass = GENERATED_BUILDER_CLASS
+                val tp = (builderExtension as ClassOrInterfaceDeclaration).typeParameters
+                BuilderType = if (tp.isEmpty()) BuilderClass
+                else "$BuilderClass<${tp.map { it.nameAsString }.joinToString(", ")}>"
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/ConstDef.kt b/tools/codegen/src/com/android/codegen/ConstDef.kt
new file mode 100644
index 0000000..f559d6f
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/ConstDef.kt
@@ -0,0 +1,17 @@
+package com.android.codegen
+
+import com.github.javaparser.ast.body.FieldDeclaration
+
+/**
+ * `@IntDef` or `@StringDef`
+ */
+data class ConstDef(val type: Type, val AnnotationName: String, val values: List<FieldDeclaration>) {
+
+    enum class Type {
+        INT, INT_FLAGS, STRING;
+
+        val isInt get() = this == INT || this == INT_FLAGS
+    }
+
+    val CONST_NAMES get() = values.flatMap { it.variables }.map { it.nameAsString }
+}
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/FeatureFlag.kt b/tools/codegen/src/com/android/codegen/FeatureFlag.kt
new file mode 100644
index 0000000..24150d6
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/FeatureFlag.kt
@@ -0,0 +1,27 @@
+package com.android.codegen
+
+
+/**
+ * See also [ClassPrinter.invoke] for more default flag values resolution rules
+ */
+enum class FeatureFlag(val onByDefault: Boolean, val desc: String = "") {
+    PARCELABLE(false, "implement Parcelable contract"),
+    AIDL(false, "generate a 'parcelable declaration' .aidl file alongside"),
+    CONSTRUCTOR(true, "an all-argument constructor"),
+    BUILDER(false, "e.g. MyClass.builder().setFoo(..).build();"),
+    GETTERS(true, "getters, e.g. getFoo()"),
+    SETTERS(false, "chainable/fluent setters, e.g. setFoo(..).setBar(..)"),
+    WITHERS(false, "'immutable setters' returning a new instance, " +
+            "e.g. newFoo = foo.withBar(barValue)"),
+    EQUALS_HASH_CODE(false, "equals + hashCode based on fields"),
+    TO_STRING(false, "toString based on fields"),
+    BUILD_UPON(false, "builder factory from existing instance, " +
+            "e.g. instance.buildUpon().setFoo(..).build()"),
+    IMPLICIT_NONNULL(true, "treat lack of @Nullable as @NonNull for Object fields"),
+    COPY_CONSTRUCTOR(false, "a constructor for an instance identical to the given one"),
+    CONST_DEFS(true, "@Int/StringDef's based on declared static constants"),
+    FOR_EACH_FIELD(false, "forEachField((name, value) -> ...)");
+
+    val kebabCase = name.toLowerCase().replace("_", "-")
+    val upperCamelCase = name.split("_").map { it.toLowerCase().capitalize() }.joinToString("")
+}
diff --git a/tools/codegen/src/com/android/codegen/FieldInfo.kt b/tools/codegen/src/com/android/codegen/FieldInfo.kt
new file mode 100644
index 0000000..f326fd5
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/FieldInfo.kt
@@ -0,0 +1,216 @@
+package com.android.codegen
+
+import com.github.javaparser.JavaParser
+import com.github.javaparser.ast.body.FieldDeclaration
+import com.github.javaparser.ast.expr.ClassExpr
+import com.github.javaparser.ast.expr.Name
+import com.github.javaparser.ast.expr.SingleMemberAnnotationExpr
+import com.github.javaparser.ast.expr.StringLiteralExpr
+import com.github.javaparser.ast.type.ArrayType
+import com.github.javaparser.ast.type.ClassOrInterfaceType
+import com.github.javaparser.javadoc.Javadoc
+import java.lang.Long
+
+data class FieldInfo(
+    val index: Int,
+    val fieldAst: FieldDeclaration,
+    private val classInfo: ClassInfo
+) {
+
+    val classPrinter = classInfo as ClassPrinter
+
+    // AST
+    internal val variableAst = fieldAst.variables[0]
+    val typeAst = variableAst.type
+
+    // Field type
+    val Type = typeAst.asString()
+    val FieldClass = Type.takeWhile { it != '<' }
+    val isPrimitive = Type in PRIMITIVE_TYPES
+
+    // Javadoc
+    val javadoc: Javadoc? = fieldAst.javadoc.orElse(null)
+    private val javadocText = javadoc?.toText()?.let {
+        // Workaround for a bug in Javaparser for javadocs starting with {
+        if (it.hasUnbalancedCurlyBrace()) "{$it" else it
+    }
+    val javadocTextNoAnnotationLines = javadocText
+            ?.lines()
+            ?.dropLastWhile { it.startsWith("@") || it.isBlank() }
+            ?.let { if (it.isEmpty()) null else it }
+    val javadocFull = javadocText
+            ?.trimBlankLines()
+            ?.mapLines { " * $this" }
+            ?.let { "/**\n$it\n */" }
+
+
+    // Field name
+    val name = variableAst.name.asString()!!
+    private val isNameHungarian = name[0] == 'm' && name[1].isUpperCase()
+    val NameUpperCamel = if (isNameHungarian) name.substring(1) else name.capitalize()
+    val nameLowerCamel = if (isNameHungarian) NameUpperCamel.decapitalize() else name
+    val _name = if (name != nameLowerCamel) nameLowerCamel else "_$nameLowerCamel"
+    val SingularNameOrNull by lazy {
+        classPrinter {
+            fieldAst.annotations
+                    .find { it.nameAsString == PluralOf }
+                    ?.let { it as? SingleMemberAnnotationExpr }
+                    ?.memberValue
+                    ?.let { it as? StringLiteralExpr }
+                    ?.value
+                    ?.toLowerCamel()
+                    ?.capitalize()
+        }
+    }
+    val SingularName by lazy { SingularNameOrNull ?: NameUpperCamel }
+
+
+    // Field value
+    val mayBeNull: Boolean
+        get() = when {
+            isPrimitive -> false
+            "@${classPrinter.NonNull}" in annotations -> false
+            "@${classPrinter.NonEmpty}" in annotations -> false
+            isNullable -> true
+            lazyInitializer != null -> true
+            else -> classPrinter { !FeatureFlag.IMPLICIT_NONNULL() }
+        }
+    val lazyInitializer
+        get() = classInfo.classAst.methods.find { method ->
+            method.nameAsString == "lazyInit$NameUpperCamel" && method.parameters.isEmpty()
+        }?.nameAsString
+    val internalGetter get() = if (lazyInitializer != null) "get$NameUpperCamel()" else name
+    val defaultExpr: Any?
+        get() {
+            variableAst.initializer.orElse(null)?.let { return it }
+            classInfo.classAst.methods.find {
+                it.nameAsString == "default$NameUpperCamel" && it.parameters.isEmpty()
+            }?.run { "$nameAsString()" }?.let { return it }
+            if (FieldClass == "List") return "${classPrinter.memberRef("java.util.Collections.emptyList")}()"
+            return null
+        }
+    val hasDefault get() = defaultExpr != null
+
+
+    // Generic args
+    val isArray = Type.endsWith("[]")
+    val isList = FieldClass == "List" || FieldClass == "ArrayList"
+    val fieldBit = "0x${Long.toHexString(1L shl index)}"
+    var isLast = false
+    val isFinal = fieldAst.isFinal
+    val fieldTypeGenegicArgs = when (typeAst) {
+        is ArrayType -> listOf(fieldAst.elementType.asString())
+        is ClassOrInterfaceType -> {
+            typeAst.typeArguments.orElse(null)?.map { it.asString() } ?: emptyList()
+        }
+        else -> emptyList()
+    }
+    val FieldInnerType = fieldTypeGenegicArgs.firstOrNull()
+    val FieldInnerClass = FieldInnerType?.takeWhile { it != '<' }
+
+
+    // Annotations
+    var intOrStringDef = null as ConstDef?
+    val annotations by lazy {
+        if (FieldClass in BUILTIN_SPECIAL_PARCELLINGS) {
+            classPrinter {
+                fieldAst.addAnnotation(SingleMemberAnnotationExpr(
+                        Name(ParcelWith),
+                        ClassExpr(JavaParser.parseClassOrInterfaceType(
+                                "$Parcelling.BuiltIn.For$FieldClass"))))
+            }
+        }
+        fieldAst.annotations.map { it.removeComment().toString() }
+    }
+    val annotationsNoInternal by lazy {
+        annotations.filterNot { ann ->
+            classPrinter {
+                internalAnnotations.any {
+                    it in ann
+                }
+            }
+        }
+    }
+
+    fun hasAnnotation(a: String) = annotations.any { it.startsWith(a) }
+    val isNullable by lazy { hasAnnotation("@Nullable") }
+    val isNonEmpty by lazy { hasAnnotation("@${classPrinter.NonEmpty}") }
+    val customParcellingClass by lazy {
+        fieldAst.annotations.find { it.nameAsString == classPrinter.ParcelWith }
+                ?.singleArgAs<ClassExpr>()
+                ?.type
+                ?.asString()
+    }
+    val annotationsAndType by lazy { (annotationsNoInternal + Type).joinToString(" ") }
+    val sParcelling by lazy { customParcellingClass?.let { "sParcellingFor$NameUpperCamel" } }
+    val annotatedTypeForSetterParam by lazy {
+        (annotationsNoInternal + if (isArray) "$FieldInnerType..." else Type).joinToString(" ")
+    }
+
+    // Utilities
+
+    /**
+     * `mFoo.size()`
+     */
+    val ClassPrinter.sizeExpr get() = when {
+        isArray && FieldInnerClass !in PRIMITIVE_TYPES ->
+            memberRef("com.android.internal.util.ArrayUtils.size") + "($name)"
+        isArray -> "$name.length"
+        listOf("List", "Set", "Map").any { FieldClass.endsWith(it) } ->
+            memberRef("com.android.internal.util.CollectionUtils.size") + "($name)"
+        Type == "String" -> memberRef("android.text.TextUtils.length") + "($name)"
+        Type == "CharSequence" -> "$name.length()"
+        else -> "$name.size()"
+    }
+    /**
+     * `mFoo.get(0)`
+     */
+    fun elemAtIndexExpr(indexExpr: String) = when {
+        isArray -> "$name[$indexExpr]"
+        FieldClass == "ArraySet" -> "$name.valueAt($indexExpr)"
+        else -> "$name.get($indexExpr)"
+    }
+    /**
+     * `mFoo.isEmpty()`
+     */
+    val ClassPrinter.isEmptyExpr get() = when {
+        isArray || Type == "CharSequence" -> "$sizeExpr == 0"
+        else -> "$name.isEmpty()"
+    }
+
+    /**
+     * `mFoo == that` or `Objects.equals(mFoo, that)`, etc.
+     */
+    fun ClassPrinter.isEqualToExpr(that: String) = when {
+        Type in PRIMITIVE_TYPES -> "$internalGetter == $that"
+        isArray -> "${memberRef("java.util.Arrays.equals")}($internalGetter, $that)"
+        else -> "${memberRef("java.util.Objects.equals")}($internalGetter, $that)"
+    }
+
+    /**
+     * Parcel.write* and Parcel.read* method name wildcard values
+     */
+    val ParcelMethodsSuffix = when {
+        FieldClass in PRIMITIVE_TYPES - "char" - "boolean" +
+                listOf("String", "CharSequence", "Exception", "Size", "SizeF", "Bundle",
+                        "FileDescriptor", "SparseBooleanArray", "SparseIntArray", "SparseArray") ->
+            FieldClass
+        FieldClass == "Map" && fieldTypeGenegicArgs[0] == "String" -> "Map"
+        isArray -> when {
+            FieldInnerType!! in (PRIMITIVE_TYPES + "String") -> FieldInnerType + "Array"
+            isBinder(FieldInnerType) -> "BinderArray"
+            else -> "TypedArray"
+        }
+        isList -> when {
+            FieldInnerType == "String" -> "StringList"
+            isBinder(FieldInnerType!!) -> "BinderList"
+            else -> "ParcelableList"
+        }
+        isIInterface(Type) -> "StrongInterface"
+        isBinder(Type) -> "StrongBinder"
+        else -> "TypedObject"
+    }.capitalize()
+
+    private fun isBinder(type: String) = type == "Binder" || type == "IBinder" || isIInterface(type)
+    private fun isIInterface(type: String) = type.length >= 2 && type[0] == 'I' && type[1].isUpperCase()
+}
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/Generators.kt b/tools/codegen/src/com/android/codegen/Generators.kt
new file mode 100644
index 0000000..ab64f4e
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/Generators.kt
@@ -0,0 +1,847 @@
+package com.android.codegen
+
+import com.github.javaparser.ast.body.FieldDeclaration
+import com.github.javaparser.ast.body.VariableDeclarator
+import com.github.javaparser.ast.expr.*
+import java.io.File
+
+
+/**
+ * IntDefs and StringDefs based on constants
+ */
+fun ClassPrinter.generateConstDefs() {
+    val consts = classAst.fields.filter {
+        it.isStatic && it.isFinal && it.variables.all { variable ->
+            val initializer = variable.initializer.orElse(null)
+            val isLiteral = initializer is LiteralExpr
+                    || (initializer is UnaryExpr && initializer.expression is LiteralExpr)
+            isLiteral && variable.type.asString() in listOf("int", "String")
+        }
+    }.flatMap { field -> field.variables.map { it to field } }
+    val intConsts = consts.filter { it.first.type.asString() == "int" }
+    val strConsts = consts.filter { it.first.type.asString() == "String" }
+    val intGroups = intConsts.groupBy { it.first.nameAsString.split("_")[0] }.values
+    val strGroups = strConsts.groupBy { it.first.nameAsString.split("_")[0] }.values
+    intGroups.forEach {
+        generateConstDef(it)
+    }
+    strGroups.forEach {
+        generateConstDef(it)
+    }
+}
+
+fun ClassPrinter.generateConstDef(consts: List<Pair<VariableDeclarator, FieldDeclaration>>) {
+    if (consts.size <= 1) return
+
+    val names = consts.map { it.first.nameAsString!! }
+    val prefix = names
+            .reduce { a, b -> a.commonPrefixWith(b) }
+            .dropLastWhile { it != '_' }
+            .dropLast(1)
+    if (prefix.isEmpty()) {
+        println("Failed to generate const def for $names")
+        return
+    }
+    var AnnotationName = prefix.split("_")
+            .filterNot { it.isBlank() }
+            .map { it.toLowerCase().capitalize() }
+            .joinToString("")
+    val annotatedConst = consts.find { it.second.annotations.isNonEmpty }
+    if (annotatedConst != null) {
+        AnnotationName = annotatedConst.second.annotations.first().nameAsString
+    }
+    val type = consts[0].first.type.asString()
+    val flag = type == "int" && consts.all { it.first.initializer.get().toString().startsWith("0x") }
+    val constDef = ConstDef(type = when {
+        type == "String" -> ConstDef.Type.STRING
+        flag -> ConstDef.Type.INT_FLAGS
+        else -> ConstDef.Type.INT
+    },
+            AnnotationName = AnnotationName,
+            values = consts.map { it.second }
+    )
+    constDefs += constDef
+    fields.forEachApply {
+        if (fieldAst.annotations.any { it.nameAsString == AnnotationName }) {
+            this.intOrStringDef = constDef
+        }
+    }
+
+    val visibility = if (consts[0].second.isPublic) "public" else "/* package-*/"
+
+    val Retention = classRef("java.lang.annotation.Retention")
+    val RetentionPolicySource = memberRef("java.lang.annotation.RetentionPolicy.SOURCE")
+    val ConstDef = classRef("android.annotation.${type.capitalize()}Def")
+
+    "@$ConstDef(${if_(flag, "flag = true, ")}prefix = \"${prefix}_\", value = {" {
+        names.forEachLastAware { name, isLast ->
+            +"$name${if_(!isLast, ",")}"
+        }
+    } + ")"
+    +"@$Retention($RetentionPolicySource)"
+    +GENERATED_MEMBER_HEADER
+    +"$visibility @interface $AnnotationName {}"
+    +""
+
+    if (type == "int") {
+        +GENERATED_MEMBER_HEADER
+        val methodDefLine = "$visibility static String ${AnnotationName.decapitalize()}ToString(" +
+                "@$AnnotationName int value)"
+        if (flag) {
+            val flg2str = memberRef("com.android.internal.util.BitUtils.flagsToString")
+            methodDefLine {
+                "return $flg2str(" {
+                    +"value, $ClassName::single${AnnotationName}ToString"
+                } + ";"
+            }
+            +GENERATED_MEMBER_HEADER
+            !"static String single${AnnotationName}ToString(@$AnnotationName int value)"
+        } else {
+            !methodDefLine
+        }
+        " {" {
+            "switch (value) {" {
+                names.forEach { name ->
+                    "case $name:" {
+                        +"return \"$name\";"
+                    }
+                }
+                +"default: return Integer.toHexString(value);"
+            }
+        }
+    }
+}
+
+fun ClassPrinter.generateAidl(javaFile: File) {
+    val aidl = File(javaFile.path.substringBeforeLast(".java") + ".aidl")
+    if (aidl.exists()) return
+    aidl.writeText(buildString {
+        sourceLines.dropLastWhile { !it.startsWith("package ") }.forEach {
+            appendln(it)
+        }
+        append("\nparcelable $ClassName;\n")
+    })
+}
+
+/**
+ * ```
+ * Foo newFoo = oldFoo.withBar(newBar);
+ * ```
+ */
+fun ClassPrinter.generateWithers() {
+    fields.forEachApply {
+        val metodName = "with$NameUpperCamel"
+        if (!hasMethod(metodName, Type)) {
+            generateFieldJavadoc(forceHide = FeatureFlag.WITHERS.hidden)
+            """@$NonNull
+                        $GENERATED_MEMBER_HEADER
+                        public $ClassType $metodName($annotatedTypeForSetterParam value)""" {
+                val changedFieldName = name
+
+                "return new $ClassType(" {
+                    fields.forEachTrimmingTrailingComma {
+                        if (name == changedFieldName) +"value," else +"$name,"
+                    }
+                } + ";"
+            }
+        }
+    }
+}
+
+fun ClassPrinter.generateCopyConstructor() {
+    if (classAst.constructors.any {
+                it.parameters.size == 1 &&
+                        it.parameters[0].type.asString() == ClassType
+            }) {
+        return
+    }
+
+    +"/** Copy constructor */"
+    +GENERATED_MEMBER_HEADER
+    "public $ClassName(@$NonNull $ClassName orig)" {
+        fields.forEachApply {
+            +"$name = orig.$name;"
+        }
+    }
+}
+
+/**
+ * ```
+ * Foo newFoo = oldFoo.buildUpon().setBar(newBar).build();
+ * ```
+ */
+fun ClassPrinter.generateBuildUpon() {
+    if (hasMethod("buildUpon")) return
+
+    +"/**"
+    +" * Provides an instance of {@link $BuilderClass} with state corresponding to this instance."
+    if (FeatureFlag.BUILD_UPON.hidden) {
+        +" * @hide"
+    }
+    +" */"
+    +GENERATED_MEMBER_HEADER
+    "public $BuilderType buildUpon()" {
+        "return new $BuilderType()" {
+            fields.forEachApply {
+                +".set$NameUpperCamel($internalGetter)"
+            } + ";"
+        }
+    }
+}
+
+fun ClassPrinter.generateBuilder() {
+    val setterVisibility = if (cliArgs.contains(FLAG_BUILDER_PROTECTED_SETTERS))
+        "protected" else "public"
+    val constructorVisibility = if (BuilderClass == CANONICAL_BUILDER_CLASS)
+        "public" else "/* package-*/"
+
+    val OneTimeUseBuilder = classRef("android.provider.OneTimeUseBuilder")
+
+    +"/**"
+    +" * A builder for {@link $ClassName}"
+    if (FeatureFlag.BUILDER.hidden) +" * @hide"
+    +" */"
+    +"@SuppressWarnings(\"WeakerAccess\")"
+    +GENERATED_MEMBER_HEADER
+    "public static class $BuilderClass$genericArgs" {
+        +"extends $OneTimeUseBuilder<$ClassType>"
+    }
+    " {" {
+
+        +""
+        fields.forEachApply {
+            +"protected $annotationsAndType $name;"
+        }
+        +""
+        +"protected long mBuilderFieldsSet = 0L;"
+        +""
+        +"$constructorVisibility $BuilderClass() {};"
+        +""
+
+        generateBuilderSetters(setterVisibility)
+
+        generateBuilderBuild()
+
+        rmEmptyLine()
+    }
+}
+
+private fun ClassPrinter.generateBuilderSetters(visibility: String) {
+
+    fields.forEachApply {
+        val maybeCast =
+                if_(BuilderClass != CANONICAL_BUILDER_CLASS, " ($CANONICAL_BUILDER_CLASS)")
+
+        generateFieldJavadoc()
+        +GENERATED_MEMBER_HEADER
+        "$visibility $CANONICAL_BUILDER_CLASS set$NameUpperCamel($annotatedTypeForSetterParam value)" {
+            +"checkNotUsed();"
+            +"mBuilderFieldsSet |= $fieldBit;"
+            +"$name = value;"
+            +"return$maybeCast this;"
+        }
+
+
+        val javadocSeeSetter = "/** @see #set$NameUpperCamel */"
+        val singularNameCustomizationHint = if (SingularNameOrNull == null) {
+            "// You can refine this method's name by providing item's singular name, e.g.:\n" +
+                    "// @DataClass.PluralOf(\"item\")) mItems = ...\n\n"
+        } else ""
+
+        if (isList && FieldInnerType != null) {
+
+            +javadocSeeSetter
+            +GENERATED_MEMBER_HEADER
+            "$visibility $CANONICAL_BUILDER_CLASS add$SingularName(@$NonNull $FieldInnerType value)" {
+                !singularNameCustomizationHint
+                +"if ($name == null) set$NameUpperCamel(new $ArrayList<>());"
+                +"$name.add(value);"
+                +"return$maybeCast this;"
+            }
+        }
+
+        if (Type.contains("Map<")) {
+            val (Key, Value) = fieldTypeGenegicArgs
+
+            +javadocSeeSetter
+            +GENERATED_MEMBER_HEADER
+            "$visibility $CANONICAL_BUILDER_CLASS add$SingularName($Key key, $Value value)" {
+                !singularNameCustomizationHint
+                +"if ($name == null) set$NameUpperCamel(new $LinkedHashMap());"
+                +"$name.put(key, value);"
+                +"return$maybeCast this;"
+            }
+        }
+
+        if (Type == "boolean") {
+            +javadocSeeSetter
+            +GENERATED_MEMBER_HEADER
+            "$visibility $CANONICAL_BUILDER_CLASS mark$NameUpperCamel()" {
+                +"return set$NameUpperCamel(true);"
+            }
+
+            +javadocSeeSetter
+            +GENERATED_MEMBER_HEADER
+            "$visibility $CANONICAL_BUILDER_CLASS markNot$NameUpperCamel()" {
+                +"return set$NameUpperCamel(false);"
+            }
+        }
+    }
+}
+
+private fun ClassPrinter.generateBuilderBuild() {
+    +"/** Builds the instance. This builder should not be touched after calling this! */"
+    "public $ClassType build()" {
+        +"markUsed();"
+        fields.forEachApply {
+            if (!isNullable || hasDefault) {
+                "if ((mBuilderFieldsSet & $fieldBit) == 0)" {
+                    if (!isNullable && !hasDefault) {
+                        +"throw new IllegalStateException(\"Required field not set: $nameLowerCamel\");"
+                    } else {
+                        +"$name = $defaultExpr;"
+                    }
+                }
+            }
+        }
+        "$ClassType o = new $ClassType(" {
+            fields.forEachTrimmingTrailingComma {
+                +"$name,"
+            }
+        } + ";"
+        +"return o;"
+    }
+}
+
+fun ClassPrinter.generateParcelable() {
+    val booleanFields = fields.filter { it.Type == "boolean" }
+    val objectFields = fields.filter { it.Type !in PRIMITIVE_TYPES }
+    val nullableFields = objectFields.filter { it.mayBeNull }
+    val nonBooleanFields = fields - booleanFields
+
+
+    val flagStorageType = when (fields.size) {
+        in 0..7 -> "byte"
+        in 8..15 -> "int"
+        in 16..31 -> "long"
+        else -> throw NotImplementedError("32+ field classes not yet supported")
+    }
+    val FlagStorageType = flagStorageType.capitalize()
+
+    fields.forEachApply {
+        if (sParcelling != null) {
+            +GENERATED_MEMBER_HEADER
+            "static $Parcelling<$Type> $sParcelling =" {
+                "$Parcelling.Cache.get(" {
+                    +"$customParcellingClass.class"
+                } + ";"
+            }
+            "static {" {
+                "if ($sParcelling == null)" {
+                    "$sParcelling = $Parcelling.Cache.put(" {
+                        +"new $customParcellingClass()"
+                    } + ";"
+                }
+            }
+            +""
+        }
+    }
+
+    val Parcel = classRef("android.os.Parcel")
+    if (!hasMethod("writeToParcel", Parcel, "int")) {
+        +"@Override"
+        +GENERATED_MEMBER_HEADER
+        "public void writeToParcel($Parcel dest, int flags)" {
+            +"// You can override field parcelling by defining methods like:"
+            +"// void parcelFieldName(Parcel dest, int flags) { ... }"
+            +""
+
+            if (booleanFields.isNotEmpty() || nullableFields.isNotEmpty()) {
+                +"$flagStorageType flg = 0;"
+                booleanFields.forEachApply {
+                    +"if ($internalGetter) flg |= $fieldBit;"
+                }
+                nullableFields.forEachApply {
+                    +"if ($internalGetter != null) flg |= $fieldBit;"
+                }
+                +"dest.write$FlagStorageType(flg);"
+            }
+
+            nonBooleanFields.forEachApply {
+                val customParcellingMethod = "parcel$NameUpperCamel"
+                when {
+                    hasMethod(customParcellingMethod, Parcel, "int") ->
+                        +"$customParcellingMethod(dest, flags);"
+                    customParcellingClass != null -> +"$sParcelling.parcel($name, dest, flags);"
+                    hasAnnotation("@$DataClassEnum") ->
+                        +"dest.writeInt($internalGetter == null ? -1 : $internalGetter.ordinal());"
+                    else -> {
+                        if (mayBeNull) !"if ($internalGetter != null) "
+                        var args = internalGetter
+                        if (ParcelMethodsSuffix.startsWith("Parcelable")
+                                || ParcelMethodsSuffix.startsWith("TypedObject")
+                                || ParcelMethodsSuffix == "TypedArray") {
+                            args += ", flags"
+                        }
+                        +"dest.write$ParcelMethodsSuffix($args);"
+                    }
+                }
+            }
+        }
+    }
+
+    if (!hasMethod("describeContents")) {
+        +"@Override"
+        +GENERATED_MEMBER_HEADER
+        +"public int describeContents() { return 0; }"
+        +""
+    }
+
+    if (classAst.fields.none { it.variables[0].nameAsString == "CREATOR" }) {
+        val Creator = classRef("android.os.Parcelable.Creator")
+
+        +GENERATED_MEMBER_HEADER
+        "public static final @$NonNull $Creator<$ClassName> CREATOR" {
+            +"= new $Creator<$ClassName>()"
+        }; " {" {
+
+            +"@Override"
+            "public $ClassName[] newArray(int size)" {
+                +"return new $ClassName[size];"
+            }
+
+            +"@Override"
+            +"@SuppressWarnings({\"unchecked\", \"RedundantCast\"})"
+            "public $ClassName createFromParcel($Parcel in)" {
+                +"// You can override field unparcelling by defining methods like:"
+                +"// static FieldType unparcelFieldName(Parcel in) { ... }"
+                +""
+                if (booleanFields.isNotEmpty() || nullableFields.isNotEmpty()) {
+                    +"$flagStorageType flg = in.read$FlagStorageType();"
+                }
+                booleanFields.forEachApply {
+                    +"$Type $_name = (flg & $fieldBit) != 0;"
+                }
+                nonBooleanFields.forEachApply {
+
+                    // Handle customized parceling
+                    val customParcellingMethod = "unparcel$NameUpperCamel"
+                    if (hasMethod(customParcellingMethod, Parcel)) {
+                        +"$Type $_name = $customParcellingMethod(in);"
+                    } else if (customParcellingClass != null) {
+                        +"$Type $_name = $sParcelling.unparcel(in);"
+                    } else if (hasAnnotation("@$DataClassEnum")) {
+                        val ordinal = "${_name}Ordinal"
+                        +"int $ordinal = in.readInt();"
+                        +"$Type $_name = $ordinal < 0 ? null : $FieldClass.values()[$ordinal];"
+                    } else {
+                        val methodArgs = mutableListOf<String>()
+
+                        // Create container if any
+                        val containerInitExpr = when {
+                            FieldClass.endsWith("Map") -> "new $LinkedHashMap<>()"
+                            FieldClass == "List" || FieldClass == "ArrayList" ->
+                                "new ${classRef("java.util.ArrayList")}<>()"
+//                            isArray && FieldInnerType in (PRIMITIVE_TYPES + "String") ->
+//                                "new $FieldInnerType[in.readInt()]"
+                            else -> ""
+                        }
+                        val passContainer = containerInitExpr.isNotEmpty()
+
+                        // nullcheck +
+                        // "FieldType fieldName = (FieldType)"
+                        if (passContainer) {
+                            methodArgs.add(_name)
+                            !"$Type $_name = "
+                            if (mayBeNull) {
+                                +"null;"
+                                !"if ((flg & $fieldBit) != 0) {"
+                                pushIndent()
+                                +""
+                                !"$_name = "
+                            }
+                            +"$containerInitExpr;"
+                        } else {
+                            !"$Type $_name = "
+                            if (mayBeNull) !"(flg & $fieldBit) == 0 ? null : "
+                            if (ParcelMethodsSuffix == "StrongInterface") {
+                                !"$FieldClass.Stub.asInterface("
+                            } else if (Type !in PRIMITIVE_TYPES + "String" + "Bundle" &&
+                                    (!isArray || FieldInnerType !in PRIMITIVE_TYPES + "String") &&
+                                    ParcelMethodsSuffix != "Parcelable") {
+                                !"($Type) "
+                            }
+                        }
+
+                        // Determine method args
+                        when {
+                            ParcelMethodsSuffix == "Parcelable" ->
+                                methodArgs += "$FieldClass.class.getClassLoader()"
+                            ParcelMethodsSuffix == "TypedObject" ->
+                                methodArgs += "$FieldClass.CREATOR"
+                            ParcelMethodsSuffix == "TypedArray" ->
+                                methodArgs += "$FieldInnerClass.CREATOR"
+                            ParcelMethodsSuffix.startsWith("Parcelable")
+                                    || FieldClass == "Map"
+                                    || (isList || isArray)
+                                    && FieldInnerType !in PRIMITIVE_TYPES + "String" ->
+                                methodArgs += "$FieldInnerClass.class.getClassLoader()"
+                        }
+
+                        // ...in.readFieldType(args...);
+                        when {
+                            ParcelMethodsSuffix == "StrongInterface" -> !"in.readStrongBinder"
+                            isArray -> !"in.create$ParcelMethodsSuffix"
+                            else -> !"in.read$ParcelMethodsSuffix"
+                        }
+                        !"(${methodArgs.joinToString(", ")})"
+                        if (ParcelMethodsSuffix == "StrongInterface") !")"
+                        +";"
+
+                        // Cleanup if passContainer
+                        if (passContainer && mayBeNull) {
+                            popIndent()
+                            rmEmptyLine()
+                            +"\n}"
+                        }
+                    }
+                }
+                "return new $ClassType(" {
+                    fields.forEachTrimmingTrailingComma {
+                        +"$_name,"
+                    }
+                } + ";"
+            }
+            rmEmptyLine()
+        } + ";"
+        +""
+    }
+}
+
+fun ClassPrinter.generateEqualsHashcode() {
+    if (!hasMethod("equals", "Object")) {
+        +"@Override"
+        +GENERATED_MEMBER_HEADER
+        "public boolean equals(Object o)" {
+            +"// You can override field equality logic by defining either of the methods like:"
+            +"// boolean fieldNameEquals($ClassName other) { ... }"
+            +"// boolean fieldNameEquals(FieldType otherValue) { ... }"
+            +""
+            """if (this == o) return true;
+                        if (o == null || getClass() != o.getClass()) return false;
+                        @SuppressWarnings("unchecked")
+                        $ClassType that = ($ClassType) o;
+                        //noinspection PointlessBooleanExpression
+                        return true""" {
+                fields.forEachApply {
+                    val sfx = if (isLast) ";" else ""
+                    val customEquals = "${nameLowerCamel}Equals"
+                    when {
+                        hasMethod(customEquals, Type) -> +"&& $customEquals(that.$internalGetter)$sfx"
+                        hasMethod(customEquals, ClassType) -> +"&& $customEquals(that)$sfx"
+                        else -> +"&& ${isEqualToExpr("that.$internalGetter")}$sfx"
+                    }
+                }
+            }
+        }
+    }
+
+    if (!hasMethod("hashCode")) {
+        +"@Override"
+        +GENERATED_MEMBER_HEADER
+        "public int hashCode()" {
+            +"// You can override field hashCode logic by defining methods like:"
+            +"// int fieldNameHashCode() { ... }"
+            +""
+            +"int _hash = 1;"
+            fields.forEachApply {
+                !"_hash = 31 * _hash + "
+                val customHashCode = "${nameLowerCamel}HashCode"
+                when {
+                    hasMethod(customHashCode) -> +"$customHashCode();"
+                    Type == "int" || Type == "byte" -> +"$internalGetter;"
+                    Type in PRIMITIVE_TYPES -> +"${Type.capitalize()}.hashCode($internalGetter);"
+                    isArray -> +"${memberRef("java.util.Arrays.hashCode")}($internalGetter);"
+                    else -> +"${memberRef("java.util.Objects.hashCode")}($internalGetter);"
+                }
+            }
+            +"return _hash;"
+        }
+    }
+}
+
+//TODO support IntDef flags?
+fun ClassPrinter.generateToString() {
+    if (!hasMethod("toString")) {
+        +"@Override"
+        +GENERATED_MEMBER_HEADER
+        "public String toString()" {
+            +"// You can override field toString logic by defining methods like:"
+            +"// String fieldNameToString() { ... }"
+            +""
+            "return \"$ClassName { \" +" {
+                fields.forEachApply {
+                    val customToString = "${nameLowerCamel}ToString"
+                    val expr = when {
+                        hasMethod(customToString) -> "$customToString()"
+                        isArray -> "${memberRef("java.util.Arrays.toString")}($internalGetter)"
+                        intOrStringDef?.type?.isInt == true ->
+                            "${intOrStringDef!!.AnnotationName.decapitalize()}ToString($name)"
+                        else -> internalGetter
+                    }
+                    +"\"$nameLowerCamel = \" + $expr${if_(!isLast, " + \", \"")} +"
+                }
+            }
+            +"\" }\";"
+        }
+    }
+}
+
+fun ClassPrinter.generateSetters() {
+    fields.forEachApply {
+        if (!hasMethod("set$NameUpperCamel", Type)
+                && !fieldAst.isPublic
+                && !isFinal) {
+
+            generateFieldJavadoc(forceHide = FeatureFlag.SETTERS.hidden)
+            +GENERATED_MEMBER_HEADER
+            "public $ClassType set$NameUpperCamel($annotatedTypeForSetterParam value)" {
+                generateSetFrom("value")
+                +"return this;"
+            }
+        }
+    }
+}
+
+fun ClassPrinter.generateGetters() {
+    (fields + lazyTransientFields).forEachApply {
+        val methodPrefix = if (Type == "boolean") "is" else "get"
+        val methodName = methodPrefix + NameUpperCamel
+
+        if (!hasMethod(methodName) && !fieldAst.isPublic) {
+
+            generateFieldJavadoc(forceHide = FeatureFlag.GETTERS.hidden)
+            +GENERATED_MEMBER_HEADER
+            "public $annotationsAndType $methodName()" {
+                if (lazyInitializer == null) {
+                    +"return $name;"
+                } else {
+                    +"$Type $_name = $name;"
+                    "if ($_name == null)" {
+                        if (fieldAst.isVolatile) {
+                            "synchronized(this)" {
+                                +"$_name = $name;"
+                                "if ($_name == null)" {
+                                    +"$_name = $name = $lazyInitializer();"
+                                }
+                            }
+                        } else {
+                            +"// You can mark field as volatile for thread-safe double-check init"
+                            +"$_name = $name = $lazyInitializer();"
+                        }
+                    }
+                    +"return $_name;"
+                }
+            }
+        }
+    }
+}
+
+fun FieldInfo.generateFieldJavadoc(forceHide: Boolean = false) = classPrinter {
+    if (javadocFull != null || forceHide) {
+        var hidden = false
+        (javadocFull ?: "/**\n */").lines().forEach {
+            if (it.contains("@hide")) hidden = true
+            if (it.contains("*/") && forceHide && !hidden) {
+                if (javadocFull != null) +" *"
+                +" * @hide"
+            }
+            +it
+        }
+    }
+}
+
+fun FieldInfo.generateSetFrom(source: String) = classPrinter {
+    !"$name = "
+    if (Type in PRIMITIVE_TYPES || mayBeNull) {
+        +"$source;"
+    } else if (defaultExpr != null) {
+        "$source != null" {
+            +"? $source"
+            +": $defaultExpr;"
+        }
+    } else {
+        val checkNotNull = memberRef("com.android.internal.util.Preconditions.checkNotNull")
+        +"$checkNotNull($source);"
+    }
+    if (isNonEmpty) {
+        "if ($isEmptyExpr)" {
+            +"throw new IllegalArgumentException(\"$nameLowerCamel cannot be empty\");"
+        }
+    }
+}
+
+fun ClassPrinter.generateConstructor(visibility: String = "public") {
+    if (visibility == "public") {
+        generateConstructorJavadoc()
+    }
+    +GENERATED_MEMBER_HEADER
+    "$visibility $ClassName(" {
+        fields.forEachApply {
+            +"$annotationsAndType $nameLowerCamel${if_(!isLast, ",")}"
+        }
+    }
+    " {" {
+        fields.forEachApply {
+            !"this."
+            generateSetFrom(nameLowerCamel)
+        }
+
+        generateStateValidation()
+
+        generateOnConstructedCallback()
+    }
+}
+
+private fun ClassPrinter.generateConstructorJavadoc() {
+    if (fields.all { it.javadoc == null } && !FeatureFlag.CONSTRUCTOR.hidden) return
+    +"/**"
+    fields.filter { it.javadoc != null }.forEachApply {
+        javadocTextNoAnnotationLines?.apply {
+            +" * @param $nameLowerCamel"
+            forEach {
+                +" *   $it"
+            }
+        }
+    }
+    if (FeatureFlag.CONSTRUCTOR.hidden) +" * @hide"
+    +" */"
+}
+
+private fun ClassPrinter.generateStateValidation() {
+    val Size = classRef("android.annotation.Size")
+    val knownNonValidationAnnotations = internalAnnotations + Nullable
+
+    val validate = memberRef("com.android.internal.util.AnnotationValidations.validate")
+    fun appendValidateCall(annotation: AnnotationExpr, valueToValidate: String) {
+        "$validate(" {
+            !"${annotation.nameAsString}.class, null, $valueToValidate"
+            val params = when (annotation) {
+                is MarkerAnnotationExpr -> emptyMap()
+                is SingleMemberAnnotationExpr -> mapOf("value" to annotation.memberValue)
+                is NormalAnnotationExpr ->
+                    annotation.pairs.map { it.name.asString() to it.value }.toMap()
+                else -> throw IllegalStateException()
+            }
+            params.forEach { name, value ->
+                !",\n\"$name\", $value"
+            }
+        }
+        +";"
+    }
+
+    fields.forEachApply {
+        if (intOrStringDef != null) {
+            if (intOrStringDef!!.type == ConstDef.Type.INT_FLAGS) {
+                +""
+                +"//noinspection PointlessBitwiseExpression"
+                "$Preconditions.checkFlagsArgument(" {
+                    "$name, 0" {
+                        intOrStringDef!!.CONST_NAMES.forEach {
+                            +"| $it"
+                        }
+                    }
+                }
+                +";"
+            } else {
+                +""
+                +"//noinspection PointlessBooleanExpression"
+                "if (true" {
+                    intOrStringDef!!.CONST_NAMES.forEach { CONST_NAME ->
+                        +"&& !(${isEqualToExpr(CONST_NAME)})"
+                    }
+                }; rmEmptyLine(); ") {" {
+                    "throw new ${classRef<IllegalArgumentException>()}(" {
+                        "\"$nameLowerCamel was \" + $internalGetter + \" but must be one of: \"" {
+
+                            intOrStringDef!!.CONST_NAMES.forEachLastAware { CONST_NAME, isLast ->
+                                +"""+ "$CONST_NAME(" + $CONST_NAME + ")${if_(!isLast, ", ")}""""
+                            }
+                        }
+                    }
+                    +";"
+                }
+            }
+        }
+
+        val eachLine = fieldAst.annotations.find { it.nameAsString == Each }?.range?.orElse(null)?.end?.line
+        val perElementValidations = if (eachLine == null) emptyList() else fieldAst.annotations.filter {
+            it.nameAsString != Each &&
+                it.range.orElse(null)?.begin?.line?.let { it >= eachLine } ?: false
+        }
+
+        fieldAst.annotations.filterNot {
+            it.nameAsString == intOrStringDef?.AnnotationName
+                    || it.nameAsString in knownNonValidationAnnotations
+                    || it in perElementValidations
+        }.forEach { annotation ->
+            appendValidateCall(annotation,
+                    valueToValidate = if (annotation.nameAsString == Size) sizeExpr else name)
+        }
+
+        if (perElementValidations.isNotEmpty()) {
+            +"int ${nameLowerCamel}Size = $sizeExpr;"
+            "for (int i = 0; i < ${nameLowerCamel}Size; i++) {" {
+                perElementValidations.forEach { annotation ->
+                    appendValidateCall(annotation,
+                            valueToValidate = elemAtIndexExpr("i"))
+                }
+            }
+        }
+    }
+}
+
+private fun ClassPrinter.generateOnConstructedCallback(prefix: String = "") {
+    +""
+    val call = "${prefix}onConstructed();"
+    if (hasMethod("onConstructed")) {
+        +call
+    } else {
+        +"// $call // You can define this method to get a callback"
+    }
+}
+
+fun ClassPrinter.generateForEachField() {
+    val specializations = listOf("Object", "int")
+    val usedSpecializations = fields.map { if (it.Type in specializations) it.Type else "Object" }
+    val usedSpecializationsSet = usedSpecializations.toSet()
+
+    val PerObjectFieldAction = classRef("com.android.internal.util.DataClass.PerObjectFieldAction")
+
+    +GENERATED_MEMBER_HEADER
+    "void forEachField(" {
+        usedSpecializationsSet.toList().forEachLastAware { specType, isLast ->
+            val SpecType = specType.capitalize()
+            val ActionClass = classRef("com.android.internal.util.DataClass.Per${SpecType}FieldAction")
+            +"$ActionClass<$ClassType> action$SpecType${if_(!isLast, ",")}"
+        }
+    }; " {" {
+        usedSpecializations.forEachIndexed { i, specType ->
+            val SpecType = specType.capitalize()
+            fields[i].apply {
+                +"action$SpecType.accept$SpecType(this, \"$nameLowerCamel\", $name);"
+            }
+        }
+    }
+
+    if (usedSpecializationsSet.size > 1) {
+        +"/** @deprecated May cause boxing allocations - use with caution! */"
+        +"@Deprecated"
+        +GENERATED_MEMBER_HEADER
+        "void forEachField($PerObjectFieldAction<$ClassType> action)" {
+            fields.forEachApply {
+                +"action.acceptObject(this, \"$nameLowerCamel\", $name);"
+            }
+        }
+    }
+}
diff --git a/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt b/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt
new file mode 100644
index 0000000..d1dc88f
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt
@@ -0,0 +1,122 @@
+package com.android.codegen
+
+import com.github.javaparser.ast.body.TypeDeclaration
+import com.github.javaparser.ast.expr.*
+import com.github.javaparser.ast.nodeTypes.NodeWithAnnotations
+import com.github.javaparser.ast.type.ClassOrInterfaceType
+import com.github.javaparser.ast.type.Type
+
+
+fun ClassPrinter.getInputSignatures(): List<String> {
+    return classAst.fields.map { fieldAst ->
+        buildString {
+            append(fieldAst.modifiers.joinToString(" ") {it.asString()})
+            append(" ")
+            append(annotationsToString(fieldAst))
+            append(" ")
+            append(getFullClassName(fieldAst.commonType))
+            append(" ")
+            append(fieldAst.variables.joinToString(", ") { it.nameAsString })
+        }
+    } + classAst.methods.map { methodAst ->
+        buildString {
+            append(methodAst.modifiers.joinToString(" ") {it.asString()})
+            append(" ")
+            append(annotationsToString(methodAst))
+            append(" ")
+            append(getFullClassName(methodAst.type))
+            append(" ")
+            append(methodAst.nameAsString)
+            append("(")
+            append(methodAst.parameters.joinToString(",") {getFullClassName(it.type)})
+            append(")")
+        }
+    }
+}
+
+private fun ClassPrinter.annotationsToString(annotatedAst: NodeWithAnnotations<*>): String {
+    return annotatedAst.annotations.joinToString(" ") {
+        annotationToString(it)
+    }
+}
+
+private fun ClassPrinter.annotationToString(ann: AnnotationExpr): String {
+    return buildString {
+        append("@")
+        append(getFullClassName(ann.nameAsString))
+        if (ann is MarkerAnnotationExpr) return@buildString
+
+        append("(")
+
+        when (ann) {
+            is SingleMemberAnnotationExpr -> {
+                appendExpr(this, ann.memberValue)
+            }
+            is NormalAnnotationExpr -> {
+                ann.pairs.forEachLastAware { pair, isLast ->
+                    append(pair.nameAsString)
+                    append("=")
+                    appendExpr(this, pair.value)
+                    if (!isLast) append(", ")
+                }
+            }
+        }
+
+        append(")")
+    }.replace("\"", "\\\"")
+}
+
+private fun ClassPrinter.appendExpr(sb: StringBuilder, ex: Expression?) {
+    when (ex) {
+        is ClassExpr -> sb.append(getFullClassName(ex.typeAsString)).append(".class")
+        is IntegerLiteralExpr -> sb.append(ex.asInt()).append("L")
+        is LongLiteralExpr -> sb.append(ex.asLong()).append("L")
+        is DoubleLiteralExpr -> sb.append(ex.asDouble())
+        else -> sb.append(ex)
+    }
+}
+
+private fun ClassPrinter.getFullClassName(type: Type): String {
+    return if (type is ClassOrInterfaceType) {
+        getFullClassName(buildString {
+            type.scope.ifPresent { append(it).append(".") }
+            type.isArrayType
+            append(type.nameAsString)
+        }) + (type.typeArguments.orElse(null)?.let { args -> args.joinToString(", ") {getFullClassName(it)}}?.let { "<$it>" } ?: "")
+    } else getFullClassName(type.asString())
+}
+
+private fun ClassPrinter.getFullClassName(className: String): String {
+    if (className.endsWith("[]")) return getFullClassName(className.removeSuffix("[]")) + "[]"
+
+    if (className.matches("\\.[a-z]".toRegex())) return className //qualified name
+
+    if ("." in className) return getFullClassName(className.substringBeforeLast(".")) + "." + className.substringAfterLast(".")
+
+    fileAst.imports.find { imp ->
+        imp.nameAsString.endsWith(".$className")
+    }?.nameAsString?.let { return it }
+
+    val thisPackagePrefix = fileAst.packageDeclaration.map { it.nameAsString + "." }.orElse("")
+    val thisClassPrefix = thisPackagePrefix + classAst.nameAsString + "."
+
+    classAst.childNodes.filterIsInstance<TypeDeclaration<*>>().find {
+        it.nameAsString == className
+    }?.let { return thisClassPrefix + it.nameAsString }
+
+    constDefs.find { it.AnnotationName == className }?.let { return thisClassPrefix + className }
+
+    if (tryOrNull { Class.forName("java.lang.$className") } != null) {
+        return "java.lang.$className"
+    }
+
+    if (className[0].isLowerCase()) return className //primitive
+
+    return thisPackagePrefix + className
+}
+
+private inline fun <T> tryOrNull(f: () -> T?) = try {
+    f()
+} catch (e: Exception) {
+    null
+}
diff --git a/tools/codegen/src/com/android/codegen/Main.kt b/tools/codegen/src/com/android/codegen/Main.kt
new file mode 100755
index 0000000..8fafa7c
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/Main.kt
@@ -0,0 +1,199 @@
+package com.android.codegen
+
+import java.io.File
+
+
+const val THIS_SCRIPT_LOCATION = ""
+const val GENERATED_WARNING_PREFIX = "Code below generated by $CODEGEN_NAME"
+const val INDENT_SINGLE = "    "
+
+val PRIMITIVE_TYPES = listOf("byte", "short", "int", "long", "char", "float", "double", "boolean")
+
+const val CANONICAL_BUILDER_CLASS = "Builder"
+const val GENERATED_BUILDER_CLASS = "GeneratedBuilder"
+
+val BUILTIN_SPECIAL_PARCELLINGS = listOf("Pattern")
+
+const val FLAG_BUILDER_PROTECTED_SETTERS = "--builder-protected-setters"
+const val FLAG_NO_FULL_QUALIFIERS = "--no-full-qualifiers"
+
+
+/** @see [FeatureFlag] */
+val USAGE = """
+Usage: $CODEGEN_NAME [--[PREFIX-]FEATURE...] JAVAFILE
+
+Generates boilerplade parcelable/data class code at the bottom of JAVAFILE, based o fields' declaration in the given JAVAFILE's top-level class
+
+FEATURE represents some generatable code, and can be among:
+${FeatureFlag.values().map { feature ->
+    "  ${feature.kebabCase}" to feature.desc
+}.columnize(" - ")}
+
+And PREFIX can be:
+  <empty> - request to generate the feature
+    no    - suppress generation of the feature
+  hidden  - request to generate the feature with @hide
+
+Extra options:
+  --help        - view this help
+  --update-only - auto-detect flags from the previously auto-generated comment within the file
+  $FLAG_NO_FULL_QUALIFIERS
+                - when referring to classes don't use package name prefix; handy with IDE auto-import
+  $FLAG_BUILDER_PROTECTED_SETTERS
+                - make builder's setters protected to expose them as public in a subclass on a whitelist basis
+
+
+Special field modifiers and annotations:
+  transient                 - ignore the field completely
+  @Nullable                 - support null value when parcelling, and never throw on null input
+  @NonNull                  - throw on null input and don't parcel the nullness bit for the field
+  @DataClass.Enum           - parcel field as an enum value by ordinal
+  @DataClass.PluralOf(..)   - provide a singular version of a collection field name to be used in the builder's 'addFoo(..)'
+  @DataClass.ParcelWith(..) - provide a custom Parcelling class, specifying the custom (un)parcelling logic for this field
+  = <initializer>;          - provide default value and never throw if this field was not provided e.g. when using builder
+  /** ... */                - copy given javadoc on field's getters/setters/constructor params/builder setters etc.
+  @hide (in javadoc)        - force field's getters/setters/withers/builder setters to be @hide-den if generated
+
+
+Special methods/etc. you can define:
+
+  <any auto-generatable method>
+      For any method to be generated, if a method with same name and argument types is already
+      defined, than that method will not be generated.
+      This allows you to override certain details on granular basis.
+
+  void onConstructed()
+      Will be called in constructor, after all the fields have been initialized.
+      This is a good place to put any custom validation logic that you may have
+
+  static class $CANONICAL_BUILDER_CLASS extends $GENERATED_BUILDER_CLASS
+      If a class extending $GENERATED_BUILDER_CLASS is specified, generated builder's setters will
+      return the provided $CANONICAL_BUILDER_CLASS type.
+      $GENERATED_BUILDER_CLASS's constructor(s) will be package-private to encourage using $CANONICAL_BUILDER_CLASS instead
+      This allows you to extend the generated builder, adding or overriding any methods you may want
+
+
+In addition, for any field mMyField(or myField) of type FieldType you can define the following methods:
+
+  void parcelMyField(Parcel dest, int flags)
+      Allows you to provide custom logic for storing mMyField into a Parcel
+
+  static FieldType unparcelMyField(Parcel in)
+      Allows you to provide custom logic to deserialize the value of mMyField from a Parcel
+
+  String myFieldToString()
+      Allows you to provide a custom toString representation of mMyField's value
+
+  FieldType lazyInitMyField()
+      Requests a lazy initialization in getMyField(), with the provided method being the constructor
+      You may additionally mark the fields as volatile to cause this to generate a thread-safe
+      double-check locking lazy initialization
+
+  FieldType defaultMyField()
+      Allows you to provide a default value to initialize the field to, in case an explicit one
+      was not provided.
+      This is an alternative to providing a field initializer that, unlike the initializer,
+      you can use with final fields.
+
+Version: $CODEGEN_VERSION
+Questions? Feedback? Contact: eugenesusla@
+"""
+
+fun main(args: Array<String>) {
+    if (args.contains("--help")) {
+        println(USAGE)
+        System.exit(0)
+    }
+    if (args.contains("--version")) {
+        println(CODEGEN_VERSION)
+        System.exit(0)
+    }
+    val file = File(args.last())
+    val sourceLinesNoClosingBrace = file.readLines().dropLastWhile {
+        it.startsWith("}") || it.all(Char::isWhitespace)
+    }
+    val cliArgs = handleUpdateFlag(args, sourceLinesNoClosingBrace)
+    val sourceLinesAsIs = discardGeneratedCode(sourceLinesNoClosingBrace)
+    val sourceLines = sourceLinesAsIs
+            .filterNot { it.trim().startsWith("//") }
+            .map { it.trimEnd().dropWhile { it == '\n' } }
+
+    val stringBuilder = StringBuilder(sourceLinesAsIs.joinToString("\n"))
+    ClassPrinter(sourceLines, stringBuilder, cliArgs).run {
+
+        val cliExecutable = "$THIS_SCRIPT_LOCATION$CODEGEN_NAME"
+        val fileEscaped = file.absolutePath.replace(
+                System.getenv("ANDROID_BUILD_TOP"), "\$ANDROID_BUILD_TOP")
+
+
+        +"""
+
+
+
+        // $GENERATED_WARNING_PREFIX v$CODEGEN_VERSION.
+        //   on ${currentTimestamp()}
+        //
+        // DO NOT MODIFY!
+        //
+        // To regenerate run:
+        // $ $cliExecutable ${cliArgs.dropLast(1).joinToString("") { "$it " }}$fileEscaped
+        //
+        // CHECKSTYLE:OFF Generated code
+        """
+
+        if (FeatureFlag.CONST_DEFS()) generateConstDefs()
+
+        "@$DataClassGenerated(" {
+            +"time = ${System.currentTimeMillis()}L,"
+            +"codegenVersion = \"$CODEGEN_VERSION\","
+            +"sourceFile = \"${file.relativeTo(File(System.getenv("ANDROID_BUILD_TOP")))}\","
+            +"inputSignatures = \"${getInputSignatures().joinToString("\\n")}\""
+        }
+        +"\n"
+
+
+        if (FeatureFlag.CONSTRUCTOR()) {
+            generateConstructor("public")
+        } else if (FeatureFlag.BUILDER()
+                || FeatureFlag.COPY_CONSTRUCTOR()
+                || FeatureFlag.WITHERS()
+                || FeatureFlag.PARCELABLE()) {
+            generateConstructor("/* package-private */")
+        }
+
+        if (FeatureFlag.GETTERS()) generateGetters()
+        if (FeatureFlag.SETTERS()) generateSetters()
+        if (FeatureFlag.TO_STRING()) generateToString()
+        if (FeatureFlag.EQUALS_HASH_CODE()) generateEqualsHashcode()
+
+        if (FeatureFlag.FOR_EACH_FIELD()) generateForEachField()
+
+        if (FeatureFlag.COPY_CONSTRUCTOR()) generateCopyConstructor()
+        if (FeatureFlag.WITHERS()) generateWithers()
+
+        if (FeatureFlag.PARCELABLE()) generateParcelable()
+
+        if (FeatureFlag.BUILDER() && FeatureFlag.BUILD_UPON()) generateBuildUpon()
+        if (FeatureFlag.BUILDER()) generateBuilder()
+
+        if (FeatureFlag.AIDL()) generateAidl(file)
+
+        rmEmptyLine()
+    }
+    stringBuilder.append("\n}\n")
+    file.writeText(stringBuilder.toString().mapLines { trimEnd() })
+}
+
+internal fun discardGeneratedCode(sourceLinesNoClosingBrace: List<String>): List<String> {
+    return sourceLinesNoClosingBrace
+            .takeWhile { GENERATED_WARNING_PREFIX !in it }
+            .dropLastWhile(String::isBlank)
+}
+
+private fun handleUpdateFlag(cliArgs: Array<String>, sourceLines: List<String>): Array<String> {
+    if ("--update-only" in cliArgs
+            && sourceLines.none { GENERATED_WARNING_PREFIX in it || it.startsWith("@DataClass") }) {
+        System.exit(0)
+    }
+    return cliArgs - "--update-only"
+}
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/SharedConstants.kt b/tools/codegen/src/com/android/codegen/SharedConstants.kt
new file mode 100644
index 0000000..41641f6
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/SharedConstants.kt
@@ -0,0 +1,4 @@
+package com.android.codegen
+
+const val CODEGEN_NAME = "codegen"
+const val CODEGEN_VERSION = "0.0.1"
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/Utils.kt b/tools/codegen/src/com/android/codegen/Utils.kt
new file mode 100644
index 0000000..95c9909
--- /dev/null
+++ b/tools/codegen/src/com/android/codegen/Utils.kt
@@ -0,0 +1,76 @@
+package com.android.codegen
+
+import com.github.javaparser.ast.expr.AnnotationExpr
+import com.github.javaparser.ast.expr.Expression
+import com.github.javaparser.ast.expr.SingleMemberAnnotationExpr
+import java.time.Instant
+import java.time.ZoneId
+import java.time.format.DateTimeFormatter
+import java.time.format.FormatStyle
+
+/**
+ * [Iterable.forEach] + [Any.apply]
+ */
+inline fun <T> Iterable<T>.forEachApply(block: T.() -> Unit) = forEach(block)
+
+inline fun String.mapLines(f: String.() -> String?) = lines().mapNotNull(f).joinToString("\n")
+inline fun <T> Iterable<T>.trim(f: T.() -> Boolean) = dropWhile(f).dropLastWhile(f)
+fun String.trimBlankLines() = lines().trim { isBlank() }.joinToString("\n")
+
+fun Char.isNewline() = this == '\n' || this == '\r'
+fun Char.isWhitespaceNonNewline() = isWhitespace() && !isNewline()
+
+fun if_(cond: Boolean, then: String) = if (cond) then else ""
+
+inline infix fun Int.times(action: () -> Unit) {
+    for (i in 1..this) action()
+}
+
+/**
+ * a bbb
+ * cccc dd
+ *
+ * ->
+ *
+ * a    bbb
+ * cccc dd
+ */
+fun Iterable<Pair<String, String>>.columnize(separator: String = " | "): String {
+    val col1w = map { (a, _) -> a.length }.max()!!
+    val col2w = map { (_, b) -> b.length }.max()!!
+    return map { it.first.padEnd(col1w) + separator + it.second.padEnd(col2w) }.joinToString("\n")
+}
+
+fun String.hasUnbalancedCurlyBrace(): Boolean {
+    var braces = 0
+    forEach {
+        if (it == '{') braces++
+        if (it == '}') braces--
+        if (braces < 0) return true
+    }
+    return false
+}
+
+fun String.toLowerCamel(): String {
+    if (length >= 2 && this[0] == 'm' && this[1].isUpperCase()) return substring(1).capitalize()
+    if (all { it.isLetterOrDigit() }) return decapitalize()
+    return split("[^a-zA-Z0-9]".toRegex())
+            .map { it.toLowerCase().capitalize() }
+            .joinToString("")
+            .decapitalize()
+}
+
+inline fun <T> List<T>.forEachLastAware(f: (T, Boolean) -> Unit) {
+    forEachIndexed { index, t -> f(t, index == size - 1) }
+}
+
+@Suppress("UNCHECKED_CAST")
+fun <T : Expression> AnnotationExpr.singleArgAs()
+        = ((this as SingleMemberAnnotationExpr).memberValue as T)
+
+inline operator fun <reified T> Array<T>.minus(item: T) = toList().minus(item).toTypedArray()
+
+fun currentTimestamp() = DateTimeFormatter
+        .ofLocalizedDateTime(/* date */ FormatStyle.MEDIUM, /* time */ FormatStyle.LONG)
+        .withZone(ZoneId.systemDefault())
+        .format(Instant.now())
\ No newline at end of file