Addresses further review comments from ag/8000041

Including:
 - An API to opt out of Int/StringDefs generation on per-field basis
 - A way to customize Builder
 - Non-optional fields are passed in Builder constructor
 - Various adjustments to SampleDataclass examples, as requested

Test: . $ANDROID_BUILD_TOP/frameworks/base/tests/Codegen/runTest.sh
Change-Id: I32d2eec52f05d505ff07779d923e4793d3036579

8 files changed, 343 insertions, 188 deletions

diff --git a/tools/codegen/src/com/android/codegen/ClassInfo.kt b/tools/codegen/src/com/android/codegen/ClassInfo.kt
index 7ee79f651274..578fb2898480 100644
--- a/tools/codegen/src/com/android/codegen/ClassInfo.kt
+++ b/tools/codegen/src/com/android/codegen/ClassInfo.kt
@@ -18,13 +18,7 @@ open class ClassInfo(val sourceLines: List<String>) {
                 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 nestedClasses = classAst.members.filterIsInstance<ClassOrInterfaceDeclaration>()
 
     val superInterfaces = (fileAst.types[0] as ClassOrInterfaceDeclaration)
             .implementedTypes.map { it.asString() }
@@ -42,8 +36,4 @@ open class ClassInfo(val sourceLines: List<String>) {
             .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
index 33256b787964..f1645ea9a3bb 100644
--- a/tools/codegen/src/com/android/codegen/ClassPrinter.kt
+++ b/tools/codegen/src/com/android/codegen/ClassPrinter.kt
@@ -1,9 +1,9 @@
 package com.android.codegen
 
+import com.github.javaparser.ast.Modifier
 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.expr.*
 import com.github.javaparser.ast.type.ClassOrInterfaceType
 
 /**
@@ -32,10 +32,31 @@ class ClassPrinter(
     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 DataClassSuppressConstDefs by lazy { classRef("com.android.internal.util.DataClass.SuppressConstDefsGeneration") }
+    val DataClassSuppress by lazy { classRef("com.android.internal.util.DataClass.Suppress") }
     val GeneratedMember by lazy { classRef("com.android.internal.util.DataClass.Generated.Member") }
     val Parcelling by lazy { classRef("com.android.internal.util.Parcelling") }
+    val Parcelable by lazy { classRef("android.os.Parcelable") }
     val UnsupportedAppUsage by lazy { classRef("android.annotation.UnsupportedAppUsage") }
 
+    init {
+        val fieldsWithMissingNullablity = fields.filter { field ->
+            !field.isPrimitive
+                    && Modifier.TRANSIENT !in field.fieldAst.modifiers
+                    && "@$Nullable" !in field.annotations
+                    && "@$NonNull" !in field.annotations
+        }
+        if (fieldsWithMissingNullablity.isNotEmpty()) {
+            abort("Non-primitive fields must have @$Nullable or @$NonNull annotation.\n" +
+                    "Missing nullability annotations on: "
+                    + fieldsWithMissingNullablity.joinToString(", ") { it.name })
+        }
+
+        if (!classAst.isFinal &&
+                classAst.extendedTypes.any { it.nameAsString == Parcelable }) {
+            abort("Parcelable classes must be final")
+        }
+    }
 
     /**
      * Optionally shortens a class reference if there's a corresponding import present
@@ -54,7 +75,7 @@ class ClassPrinter(
             return simpleName
         } else {
             val outerClass = pkg.substringAfterLast(".", "")
-            if (outerClass.firstOrNull()?.isUpperCase() ?: false) {
+            if (outerClass.firstOrNull()?.isUpperCase() == true) {
                 return classRef(pkg) + "." + simpleName
             }
         }
@@ -89,7 +110,9 @@ class ClassPrinter(
             ?.toMap()
             ?: emptyMap()
 
-    val internalAnnotations = setOf(ParcelWith, DataClassEnum, PluralOf, Each, UnsupportedAppUsage)
+    val internalAnnotations = setOf(ParcelWith, DataClassEnum, PluralOf, UnsupportedAppUsage,
+            DataClassSuppressConstDefs)
+    val knownNonValidationAnnotations = internalAnnotations + Each + Nullable
 
     /**
      * @return whether the given feature is enabled
@@ -109,7 +132,9 @@ class ClassPrinter(
         return when (this) {
             FeatureFlag.SETTERS ->
                 !FeatureFlag.CONSTRUCTOR() && !FeatureFlag.BUILDER() && fields.any { !it.isFinal }
-            FeatureFlag.BUILDER -> cliArgs.contains(FLAG_BUILDER_PROTECTED_SETTERS) || onByDefault
+            FeatureFlag.BUILDER -> cliArgs.contains(FLAG_BUILDER_PROTECTED_SETTERS)
+                    || fields.any { it.hasDefault }
+                    || onByDefault
             FeatureFlag.CONSTRUCTOR -> !FeatureFlag.BUILDER()
             FeatureFlag.PARCELABLE -> "Parcelable" in superInterfaces
             FeatureFlag.AIDL -> FeatureFlag.PARCELABLE()
@@ -287,6 +312,48 @@ class ClassPrinter(
 
     var BuilderClass = CANONICAL_BUILDER_CLASS
     var BuilderType = BuilderClass + genericArgs
+    val customBaseBuilderAst: ClassOrInterfaceDeclaration? by lazy {
+        nestedClasses.find { it.nameAsString == BASE_BUILDER_CLASS }
+    }
+
+    val suppressedMembers by lazy {
+        getSuppressedMembers(classAst)
+    }
+    val builderSuppressedMembers by lazy {
+        getSuppressedMembers(customBaseBuilderAst)
+    }
+
+    private fun getSuppressedMembers(clazz: ClassOrInterfaceDeclaration?): List<String> {
+        return clazz
+                ?.annotations
+                ?.find { it.nameAsString == DataClassSuppress }
+                ?.as_<SingleMemberAnnotationExpr>()
+                ?.memberValue
+                ?.run {
+                    when (this) {
+                        is ArrayInitializerExpr -> values.map { it.asLiteralStringValueExpr().value }
+                        is StringLiteralExpr -> listOf(value)
+                        else -> abort("Can't parse annotation arg: $this")
+                    }
+                }
+                ?: emptyList()
+    }
+
+    fun isMethodGenerationSuppressed(name: String, vararg argTypes: String): Boolean {
+        return name in suppressedMembers || hasMethod(name, *argTypes)
+    }
+
+    fun hasMethod(name: String, vararg argTypes: String): Boolean {
+        return classAst.methods.any {
+            it.name.asString() == name &&
+                    it.parameters.map { it.type.asString() } == argTypes.toList()
+        }
+    }
+
+    val lazyTransientFields = classAst.fields
+            .filter { it.isTransient && !it.isStatic }
+            .mapIndexed { i, node -> FieldInfo(index = i, fieldAst = node, classInfo = this) }
+            .filter { hasMethod("lazyInit${it.NameUpperCamel}") }
 
     init {
         val builderFactoryOverride = classAst.methods.find {
@@ -301,7 +368,7 @@ class ClassPrinter(
                 it.nameAsString == CANONICAL_BUILDER_CLASS
             }
             if (builderExtension != null) {
-                BuilderClass = GENERATED_BUILDER_CLASS
+                BuilderClass = BASE_BUILDER_CLASS
                 val tp = (builderExtension as ClassOrInterfaceDeclaration).typeParameters
                 BuilderType = if (tp.isEmpty()) BuilderClass
                 else "$BuilderClass<${tp.map { it.nameAsString }.joinToString(", ")}>"
diff --git a/tools/codegen/src/com/android/codegen/FieldInfo.kt b/tools/codegen/src/com/android/codegen/FieldInfo.kt
index f326fd5601fe..74e79489ad7d 100644
--- a/tools/codegen/src/com/android/codegen/FieldInfo.kt
+++ b/tools/codegen/src/com/android/codegen/FieldInfo.kt
@@ -9,7 +9,6 @@ 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,
@@ -85,7 +84,7 @@ data class FieldInfo(
             variableAst.initializer.orElse(null)?.let { return it }
             classInfo.classAst.methods.find {
                 it.nameAsString == "default$NameUpperCamel" && it.parameters.isEmpty()
-            }?.run { "$nameAsString()" }?.let { return it }
+            }?.run { return "$nameAsString()" }
             if (FieldClass == "List") return "${classPrinter.memberRef("java.util.Collections.emptyList")}()"
             return null
         }
@@ -95,7 +94,7 @@ data class FieldInfo(
     // Generic args
     val isArray = Type.endsWith("[]")
     val isList = FieldClass == "List" || FieldClass == "ArrayList"
-    val fieldBit = "0x${Long.toHexString(1L shl index)}"
+    val fieldBit = bitAtExpr(index)
     var isLast = false
     val isFinal = fieldAst.isFinal
     val fieldTypeGenegicArgs = when (typeAst) {
@@ -143,8 +142,10 @@ data class FieldInfo(
     }
     val annotationsAndType by lazy { (annotationsNoInternal + Type).joinToString(" ") }
     val sParcelling by lazy { customParcellingClass?.let { "sParcellingFor$NameUpperCamel" } }
+
+    val SetterParamType = if (isArray) "$FieldInnerType..." else Type
     val annotatedTypeForSetterParam by lazy {
-        (annotationsNoInternal + if (isArray) "$FieldInnerType..." else Type).joinToString(" ")
+        (annotationsNoInternal + SetterParamType).joinToString(" ")
     }
 
     // Utilities
diff --git a/tools/codegen/src/com/android/codegen/Generators.kt b/tools/codegen/src/com/android/codegen/Generators.kt
index ab64f4efc8d8..c6e0a064f9b4 100644
--- a/tools/codegen/src/com/android/codegen/Generators.kt
+++ b/tools/codegen/src/com/android/codegen/Generators.kt
@@ -1,6 +1,7 @@
 package com.android.codegen
 
 import com.github.javaparser.ast.body.FieldDeclaration
+import com.github.javaparser.ast.body.MethodDeclaration
 import com.github.javaparser.ast.body.VariableDeclarator
 import com.github.javaparser.ast.expr.*
 import java.io.File
@@ -16,7 +17,7 @@ fun ClassPrinter.generateConstDefs() {
             val isLiteral = initializer is LiteralExpr
                     || (initializer is UnaryExpr && initializer.expression is LiteralExpr)
             isLiteral && variable.type.asString() in listOf("int", "String")
-        }
+        } && it.annotations.none { it.nameAsString == DataClassSuppressConstDefs }
     }.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" }
@@ -131,7 +132,7 @@ fun ClassPrinter.generateAidl(javaFile: File) {
 fun ClassPrinter.generateWithers() {
     fields.forEachApply {
         val metodName = "with$NameUpperCamel"
-        if (!hasMethod(metodName, Type)) {
+        if (!isMethodGenerationSuppressed(metodName, Type)) {
             generateFieldJavadoc(forceHide = FeatureFlag.WITHERS.hidden)
             """@$NonNull
                         $GENERATED_MEMBER_HEADER
@@ -171,7 +172,7 @@ fun ClassPrinter.generateCopyConstructor() {
  * ```
  */
 fun ClassPrinter.generateBuildUpon() {
-    if (hasMethod("buildUpon")) return
+    if (isMethodGenerationSuppressed("buildUpon")) return
 
     +"/**"
     +" * Provides an instance of {@link $BuilderClass} with state corresponding to this instance."
@@ -195,7 +196,15 @@ fun ClassPrinter.generateBuilder() {
     val constructorVisibility = if (BuilderClass == CANONICAL_BUILDER_CLASS)
         "public" else "/* package-*/"
 
-    val OneTimeUseBuilder = classRef("android.provider.OneTimeUseBuilder")
+    val providedSubclassAst = nestedClasses.find {
+        it.extendedTypes.any { it.nameAsString == BASE_BUILDER_CLASS }
+    }
+
+    val BuilderSupertype = if (customBaseBuilderAst != null) {
+        customBaseBuilderAst!!.nameAsString
+    } else {
+        "Object"
+    }
 
     +"/**"
     +" * A builder for {@link $ClassName}"
@@ -203,104 +212,155 @@ fun ClassPrinter.generateBuilder() {
     +" */"
     +"@SuppressWarnings(\"WeakerAccess\")"
     +GENERATED_MEMBER_HEADER
-    "public static class $BuilderClass$genericArgs" {
-        +"extends $OneTimeUseBuilder<$ClassType>"
+    !"public static class $BuilderClass$genericArgs"
+    if (BuilderSupertype != "Object") {
+        appendSameLine(" extends $BuilderSupertype")
     }
     " {" {
 
         +""
         fields.forEachApply {
-            +"protected $annotationsAndType $name;"
+            +"private $annotationsAndType $name;"
         }
         +""
-        +"protected long mBuilderFieldsSet = 0L;"
-        +""
-        +"$constructorVisibility $BuilderClass() {};"
+        +"private long mBuilderFieldsSet = 0L;"
         +""
 
+        val requiredFields = fields.filter { !it.hasDefault }
+
+        generateConstructorJavadoc(
+                fields = requiredFields,
+                ClassName = BuilderClass,
+                hidden = false)
+        "$constructorVisibility $BuilderClass(" {
+            requiredFields.forEachLastAware { field, isLast ->
+                +"${field.annotationsAndType} ${field._name}${if_(!isLast, ",")}"
+            }
+        }; " {" {
+            requiredFields.forEachApply {
+                generateSetFrom(_name)
+            }
+        }
+
         generateBuilderSetters(setterVisibility)
 
         generateBuilderBuild()
 
+        "private void checkNotUsed() {" {
+            "if ((mBuilderFieldsSet & ${bitAtExpr(fields.size)}) != 0)" {
+                "throw new IllegalStateException(" {
+                    +"\"This Builder should not be reused. Use a new Builder instance instead\""
+                }
+                +";"
+            }
+        }
+
         rmEmptyLine()
     }
 }
 
+private fun ClassPrinter.generateBuilderMethod(
+        defVisibility: String,
+        name: String,
+        ParamAnnotations: String? = null,
+        paramTypes: List<String>,
+        paramNames: List<String> = listOf("value"),
+        genJavadoc: ClassPrinter.() -> Unit,
+        genBody: ClassPrinter.() -> Unit) {
+
+    val providedMethod = customBaseBuilderAst?.members?.find {
+        it is MethodDeclaration
+                && it.nameAsString == name
+                && it.parameters.map { it.typeAsString } == paramTypes.toTypedArray().toList()
+    } as? MethodDeclaration
+
+    if ((providedMethod == null || providedMethod.isAbstract)
+            && name !in builderSuppressedMembers) {
+        val visibility = providedMethod?.visibility?.asString() ?: defVisibility
+        val ReturnType = providedMethod?.typeAsString ?: CANONICAL_BUILDER_CLASS
+        val Annotations = providedMethod?.annotations?.joinToString("\n")
+
+        genJavadoc()
+        +GENERATED_MEMBER_HEADER
+        if (providedMethod?.isAbstract == true) +"@Override"
+        if (!Annotations.isNullOrEmpty()) +Annotations
+        "$visibility @$NonNull $ReturnType $name(${if_(!ParamAnnotations.isNullOrEmpty(), "$ParamAnnotations ")}${
+                paramTypes.zip(paramNames).joinToString(", ") { (Type, paramName) -> "$Type $paramName" }
+        })" {
+            genBody()
+        }
+    }
+}
+
 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($annotatedTypeForSetterParam value)" {
+        val setterName = "set$NameUpperCamel"
+
+        generateBuilderMethod(
+                name = setterName,
+                defVisibility = visibility,
+                ParamAnnotations = annotationsNoInternal.joinToString(" "),
+                paramTypes = listOf(SetterParamType),
+                genJavadoc = { generateFieldJavadoc() }) {
             +"checkNotUsed();"
             +"mBuilderFieldsSet |= $fieldBit;"
             +"$name = value;"
             +"return$maybeCast this;"
         }
 
+        val javadocSeeSetter = "/** @see #$setterName */"
+        val adderName = "add$SingularName"
 
-        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) {
+            generateBuilderMethod(
+                    name = adderName,
+                    defVisibility = visibility,
+                    paramTypes = listOf(FieldInnerType),
+                    genJavadoc = { +javadocSeeSetter }) {
 
-            +javadocSeeSetter
-            +GENERATED_MEMBER_HEADER
-            "$visibility $CANONICAL_BUILDER_CLASS add$SingularName(@$NonNull $FieldInnerType value)" {
                 !singularNameCustomizationHint
-                +"if ($name == null) set$NameUpperCamel(new $ArrayList<>());"
+                +"if ($name == null) $setterName(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, $Value value)" {
+            generateBuilderMethod(
+                    name = adderName,
+                    defVisibility = visibility,
+                    paramTypes = fieldTypeGenegicArgs,
+                    paramNames = listOf("key", "value"),
+                    genJavadoc = { +javadocSeeSetter }) {
                 !singularNameCustomizationHint
-                +"if ($name == null) set$NameUpperCamel(new $LinkedHashMap());"
+                +"if ($name == null) $setterName(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();"
+        +"checkNotUsed();"
+        +"mBuilderFieldsSet |= ${bitAtExpr(fields.size)}; // Mark builder used"
+        +""
         fields.forEachApply {
-            if (!isNullable || hasDefault) {
+            if (hasDefault) {
                 "if ((mBuilderFieldsSet & $fieldBit) == 0)" {
-                    if (!isNullable && !hasDefault) {
-                        +"throw new IllegalStateException(\"Required field not set: $nameLowerCamel\");"
-                    } else {
-                        +"$name = $defaultExpr;"
-                    }
+                    +"$name = $defaultExpr;"
                 }
             }
         }
@@ -348,7 +408,7 @@ fun ClassPrinter.generateParcelable() {
     }
 
     val Parcel = classRef("android.os.Parcel")
-    if (!hasMethod("writeToParcel", Parcel, "int")) {
+    if (!isMethodGenerationSuppressed("writeToParcel", Parcel, "int")) {
         +"@Override"
         +GENERATED_MEMBER_HEADER
         "public void writeToParcel($Parcel dest, int flags)" {
@@ -390,7 +450,7 @@ fun ClassPrinter.generateParcelable() {
         }
     }
 
-    if (!hasMethod("describeContents")) {
+    if (!isMethodGenerationSuppressed("describeContents")) {
         +"@Override"
         +GENERATED_MEMBER_HEADER
         +"public int describeContents() { return 0; }"
@@ -442,8 +502,6 @@ fun ClassPrinter.generateParcelable() {
                             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()
@@ -519,7 +577,7 @@ fun ClassPrinter.generateParcelable() {
 }
 
 fun ClassPrinter.generateEqualsHashcode() {
-    if (!hasMethod("equals", "Object")) {
+    if (!isMethodGenerationSuppressed("equals", "Object")) {
         +"@Override"
         +GENERATED_MEMBER_HEADER
         "public boolean equals(Object o)" {
@@ -546,7 +604,7 @@ fun ClassPrinter.generateEqualsHashcode() {
         }
     }
 
-    if (!hasMethod("hashCode")) {
+    if (!isMethodGenerationSuppressed("hashCode")) {
         +"@Override"
         +GENERATED_MEMBER_HEADER
         "public int hashCode()" {
@@ -572,7 +630,7 @@ fun ClassPrinter.generateEqualsHashcode() {
 
 //TODO support IntDef flags?
 fun ClassPrinter.generateToString() {
-    if (!hasMethod("toString")) {
+    if (!isMethodGenerationSuppressed("toString")) {
         +"@Override"
         +GENERATED_MEMBER_HEADER
         "public String toString()" {
@@ -599,7 +657,7 @@ fun ClassPrinter.generateToString() {
 
 fun ClassPrinter.generateSetters() {
     fields.forEachApply {
-        if (!hasMethod("set$NameUpperCamel", Type)
+        if (!isMethodGenerationSuppressed("set$NameUpperCamel", Type)
                 && !fieldAst.isPublic
                 && !isFinal) {
 
@@ -618,7 +676,7 @@ fun ClassPrinter.generateGetters() {
         val methodPrefix = if (Type == "boolean") "is" else "get"
         val methodName = methodPrefix + NameUpperCamel
 
-        if (!hasMethod(methodName) && !fieldAst.isPublic) {
+        if (!isMethodGenerationSuppressed(methodName) && !fieldAst.isPublic) {
 
             generateFieldJavadoc(forceHide = FeatureFlag.GETTERS.hidden)
             +GENERATED_MEMBER_HEADER
@@ -662,23 +720,8 @@ fun FieldInfo.generateFieldJavadoc(forceHide: Boolean = false) = classPrinter {
 }
 
 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(\"$nameLowerCamel cannot be empty\");"
-        }
-    }
+    +"$name = $source;"
+    generateFieldValidation(field = this@generateSetFrom)
 }
 
 fun ClassPrinter.generateConstructor(visibility: String = "public") {
@@ -697,15 +740,18 @@ fun ClassPrinter.generateConstructor(visibility: String = "public") {
             generateSetFrom(nameLowerCamel)
         }
 
-        generateStateValidation()
-
         generateOnConstructedCallback()
     }
 }
 
-private fun ClassPrinter.generateConstructorJavadoc() {
+private fun ClassPrinter.generateConstructorJavadoc(
+        fields: List<FieldInfo> = this.fields,
+        ClassName: String = this.ClassName,
+        hidden: Boolean = FeatureFlag.CONSTRUCTOR.hidden) {
     if (fields.all { it.javadoc == null } && !FeatureFlag.CONSTRUCTOR.hidden) return
     +"/**"
+    +" * Creates a new $ClassName."
+    +" *"
     fields.filter { it.javadoc != null }.forEachApply {
         javadocTextNoAnnotationLines?.apply {
             +" * @param $nameLowerCamel"
@@ -718,87 +764,97 @@ private fun ClassPrinter.generateConstructorJavadoc() {
     +" */"
 }
 
-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"
+private fun ClassPrinter.appendLinesWithContinuationIndent(text: String) {
+    val lines = text.lines()
+    if (lines.isNotEmpty()) {
+        !lines[0]
+    }
+    if (lines.size >= 2) {
+        "" {
+            lines.drop(1).forEach {
+                +it
             }
         }
-        +";"
     }
+}
 
-    fields.forEachApply {
-        if (intOrStringDef != null) {
-            if (intOrStringDef!!.type == ConstDef.Type.INT_FLAGS) {
-                +""
-                +"//noinspection PointlessBitwiseExpression"
-                "$Preconditions.checkFlagsArgument(" {
-                    "$name, 0" {
-                        intOrStringDef!!.CONST_NAMES.forEach {
-                            +"| $it"
+private fun ClassPrinter.generateFieldValidation(field: FieldInfo) = field.run {
+    if (isNonEmpty) {
+        "if ($isEmptyExpr)" {
+            +"throw new IllegalArgumentException(\"$nameLowerCamel cannot be empty\");"
+        }
+    }
+    if (intOrStringDef != null) {
+        if (intOrStringDef!!.type == ConstDef.Type.INT_FLAGS) {
+            +""
+            "$Preconditions.checkFlagsArgument(" {
+                +"$name, "
+                appendLinesWithContinuationIndent(intOrStringDef!!.CONST_NAMES.joinToString("\n| "))
+            }
+            +";"
+        } else {
+            +""
+            !"if ("
+            appendLinesWithContinuationIndent(intOrStringDef!!.CONST_NAMES.joinToString("\n&& ") {
+                "!(${isEqualToExpr(it)})"
+            })
+            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, ", ")}""""
                         }
                     }
                 }
                 +";"
-            } 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 &&
+    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)
+    val Size = classRef("android.annotation.Size")
+    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"))
+            }
         }
+    }
+}
 
-        if (perElementValidations.isNotEmpty()) {
-            +"int ${nameLowerCamel}Size = $sizeExpr;"
-            "for (int i = 0; i < ${nameLowerCamel}Size; i++) {" {
-                perElementValidations.forEach { annotation ->
-                    appendValidateCall(annotation,
-                            valueToValidate = elemAtIndexExpr("i"))
-                }
-            }
+fun ClassPrinter.appendValidateCall(annotation: AnnotationExpr, valueToValidate: String) {
+    val validate = memberRef("com.android.internal.util.AnnotationValidations.validate")
+    "$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"
         }
     }
+    +";"
 }
 
 private fun ClassPrinter.generateOnConstructedCallback(prefix: String = "") {
@@ -845,3 +901,15 @@ fun ClassPrinter.generateForEachField() {
         }
     }
 }
+
+fun ClassPrinter.generateMetadata(file: File) {
+    "@$DataClassGenerated(" {
+        +"time = ${System.currentTimeMillis()}L,"
+        +"codegenVersion = \"$CODEGEN_VERSION\","
+        +"sourceFile = \"${file.relativeTo(File(System.getenv("ANDROID_BUILD_TOP")))}\","
+        +"inputSignatures = \"${getInputSignatures().joinToString("\\n")}\""
+    }
+    +""
+    +"@Deprecated"
+    +"private void __metadata() {}\n"
+}
\ No newline at end of file
diff --git a/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt b/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt
index d1dc88f4a773..1e7a2674006b 100644
--- a/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt
+++ b/tools/codegen/src/com/android/codegen/InputSignaturesComputation.kt
@@ -1,6 +1,6 @@
 package com.android.codegen
 
-import com.github.javaparser.ast.body.TypeDeclaration
+import com.github.javaparser.ast.body.ClassOrInterfaceDeclaration
 import com.github.javaparser.ast.expr.*
 import com.github.javaparser.ast.nodeTypes.NodeWithAnnotations
 import com.github.javaparser.ast.type.ClassOrInterfaceType
@@ -8,9 +8,17 @@ import com.github.javaparser.ast.type.Type
 
 
 fun ClassPrinter.getInputSignatures(): List<String> {
+    return generateInputSignaturesForClass(classAst) +
+            annotationToString(classAst.annotations.find { it.nameAsString == DataClass }) +
+            generateInputSignaturesForClass(customBaseBuilderAst)
+}
+
+private fun ClassPrinter.generateInputSignaturesForClass(classAst: ClassOrInterfaceDeclaration?): List<String> {
+    if (classAst == null) return emptyList()
+
     return classAst.fields.map { fieldAst ->
         buildString {
-            append(fieldAst.modifiers.joinToString(" ") {it.asString()})
+            append(fieldAst.modifiers.joinToString(" ") { it.asString() })
             append(" ")
             append(annotationsToString(fieldAst))
             append(" ")
@@ -20,7 +28,7 @@ fun ClassPrinter.getInputSignatures(): List<String> {
         }
     } + classAst.methods.map { methodAst ->
         buildString {
-            append(methodAst.modifiers.joinToString(" ") {it.asString()})
+            append(methodAst.modifiers.joinToString(" ") { it.asString() })
             append(" ")
             append(annotationsToString(methodAst))
             append(" ")
@@ -28,19 +36,26 @@ fun ClassPrinter.getInputSignatures(): List<String> {
             append(" ")
             append(methodAst.nameAsString)
             append("(")
-            append(methodAst.parameters.joinToString(",") {getFullClassName(it.type)})
+            append(methodAst.parameters.joinToString(",") { getFullClassName(it.type) })
             append(")")
         }
-    }
+    } + ("class ${classAst.nameAsString}" +
+            " extends ${classAst.extendedTypes.map { getFullClassName(it) }.ifEmpty { listOf("java.lang.Object") }.joinToString(", ")}" +
+            " implements [${classAst.implementedTypes.joinToString(", ") { getFullClassName(it) }}]")
 }
 
 private fun ClassPrinter.annotationsToString(annotatedAst: NodeWithAnnotations<*>): String {
-    return annotatedAst.annotations.joinToString(" ") {
-        annotationToString(it)
-    }
+    return annotatedAst
+            .annotations
+            .groupBy { it.nameAsString } // dedupe annotations by name (javaparser bug?)
+            .values
+            .joinToString(" ") {
+                annotationToString(it[0])
+            }
 }
 
-private fun ClassPrinter.annotationToString(ann: AnnotationExpr): String {
+private fun ClassPrinter.annotationToString(ann: AnnotationExpr?): String {
+    if (ann == null) return ""
     return buildString {
         append("@")
         append(getFullClassName(ann.nameAsString))
@@ -78,9 +93,9 @@ private fun ClassPrinter.appendExpr(sb: StringBuilder, ex: Expression?) {
 
 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())
@@ -100,10 +115,16 @@ private fun ClassPrinter.getFullClassName(className: String): String {
     val thisPackagePrefix = fileAst.packageDeclaration.map { it.nameAsString + "." }.orElse("")
     val thisClassPrefix = thisPackagePrefix + classAst.nameAsString + "."
 
-    classAst.childNodes.filterIsInstance<TypeDeclaration<*>>().find {
+    if (classAst.nameAsString == className) return thisPackagePrefix + classAst.nameAsString
+
+    nestedClasses.find {
         it.nameAsString == className
     }?.let { return thisClassPrefix + it.nameAsString }
 
+    if (className == CANONICAL_BUILDER_CLASS || className == BASE_BUILDER_CLASS) {
+        return thisClassPrefix + className
+    }
+
     constDefs.find { it.AnnotationName == className }?.let { return thisClassPrefix + className }
 
     if (tryOrNull { Class.forName("java.lang.$className") } != null) {
diff --git a/tools/codegen/src/com/android/codegen/Main.kt b/tools/codegen/src/com/android/codegen/Main.kt
index 8fafa7ce9b1e..f71bfd302d2e 100755
--- a/tools/codegen/src/com/android/codegen/Main.kt
+++ b/tools/codegen/src/com/android/codegen/Main.kt
@@ -9,9 +9,6 @@ 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"
@@ -66,10 +63,10 @@ Special methods/etc. you can define:
       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
+  static class $CANONICAL_BUILDER_CLASS extends $BASE_BUILDER_CLASS
+      If a class extending $BASE_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
+      $BASE_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
 
 
@@ -131,7 +128,6 @@ fun main(args: Array<String>) {
 
 
         // $GENERATED_WARNING_PREFIX v$CODEGEN_VERSION.
-        //   on ${currentTimestamp()}
         //
         // DO NOT MODIFY!
         //
@@ -143,14 +139,6 @@ fun main(args: Array<String>) {
 
         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")
@@ -160,6 +148,7 @@ fun main(args: Array<String>) {
                 || FeatureFlag.PARCELABLE()) {
             generateConstructor("/* package-private */")
         }
+        if (FeatureFlag.COPY_CONSTRUCTOR()) generateCopyConstructor()
 
         if (FeatureFlag.GETTERS()) generateGetters()
         if (FeatureFlag.SETTERS()) generateSetters()
@@ -168,7 +157,6 @@ fun main(args: Array<String>) {
 
         if (FeatureFlag.FOR_EACH_FIELD()) generateForEachField()
 
-        if (FeatureFlag.COPY_CONSTRUCTOR()) generateCopyConstructor()
         if (FeatureFlag.WITHERS()) generateWithers()
 
         if (FeatureFlag.PARCELABLE()) generateParcelable()
@@ -178,6 +166,8 @@ fun main(args: Array<String>) {
 
         if (FeatureFlag.AIDL()) generateAidl(file)
 
+        generateMetadata(file)
+
         rmEmptyLine()
     }
     stringBuilder.append("\n}\n")
diff --git a/tools/codegen/src/com/android/codegen/SharedConstants.kt b/tools/codegen/src/com/android/codegen/SharedConstants.kt
index 175eea6ef0d0..7d50ad10de00 100644
--- a/tools/codegen/src/com/android/codegen/SharedConstants.kt
+++ b/tools/codegen/src/com/android/codegen/SharedConstants.kt
@@ -1,4 +1,7 @@
 package com.android.codegen
 
 const val CODEGEN_NAME = "codegen"
-const val CODEGEN_VERSION = "1.0.0"
\ No newline at end of file
+const val CODEGEN_VERSION = "1.0.0"
+
+const val CANONICAL_BUILDER_CLASS = "Builder"
+const val BASE_BUILDER_CLASS = "BaseBuilder"
diff --git a/tools/codegen/src/com/android/codegen/Utils.kt b/tools/codegen/src/com/android/codegen/Utils.kt
index 95c99092e2ab..73ceac41682e 100644
--- a/tools/codegen/src/com/android/codegen/Utils.kt
+++ b/tools/codegen/src/com/android/codegen/Utils.kt
@@ -1,8 +1,10 @@
 package com.android.codegen
 
+import com.github.javaparser.ast.Modifier
 import com.github.javaparser.ast.expr.AnnotationExpr
 import com.github.javaparser.ast.expr.Expression
 import com.github.javaparser.ast.expr.SingleMemberAnnotationExpr
+import com.github.javaparser.ast.nodeTypes.NodeWithModifiers
 import java.time.Instant
 import java.time.ZoneId
 import java.time.format.DateTimeFormatter
@@ -22,6 +24,8 @@ fun Char.isWhitespaceNonNewline() = isWhitespace() && !isNewline()
 
 fun if_(cond: Boolean, then: String) = if (cond) then else ""
 
+fun <T> Any?.as_(): T = this as T
+
 inline infix fun Int.times(action: () -> Unit) {
     for (i in 1..this) action()
 }
@@ -73,4 +77,15 @@ inline operator fun <reified T> Array<T>.minus(item: T) = toList().minus(item).t
 fun currentTimestamp() = DateTimeFormatter
         .ofLocalizedDateTime(/* date */ FormatStyle.MEDIUM, /* time */ FormatStyle.LONG)
         .withZone(ZoneId.systemDefault())
-        .format(Instant.now())
\ No newline at end of file
+        .format(Instant.now())
+
+val NodeWithModifiers<*>.visibility get() = Modifier.getAccessSpecifier(modifiers)
+
+fun abort(msg: String): Nothing {
+    System.err.println("ERROR: $msg")
+    System.exit(1)
+    throw InternalError() // can't get here
+}
+
+fun bitAtExpr(bitIndex: Int) = "0x${java.lang.Long.toHexString(1L shl bitIndex)}"
+