Add support for builder-getters to AutoBuilder.

A builder-getter is a method in the builder interface that lets you see what value has been set for a property of the builder. Like `@AutoValue.Builder`, the getter for a property of type `T` can return either `T` or `Optional<T>`. Trying to get a property that has not been set will provoke an exception for the former or return `Optional.empty()` for the latter.

With `@AutoValue.Builder`, a builder-getter method corresponds to a method with the same signature in the `@AutoValue` class. Here, a builder-getter method corresponds to a parameter with the same name and type, except that the builder-getter for parameter `foo` can be either `foo()` or `getFoo()`.

RELNOTES=n/a
PiperOrigin-RevId: 368222631

6 files changed, 81 insertions, 45 deletions

diff --git a/value/src/main/java/com/google/auto/value/processor/AutoBuilderProcessor.java b/value/src/main/java/com/google/auto/value/processor/AutoBuilderProcessor.java
index b2310875..a04c30c6 100644
--- a/value/src/main/java/com/google/auto/value/processor/AutoBuilderProcessor.java
+++ b/value/src/main/java/com/google/auto/value/processor/AutoBuilderProcessor.java
@@ -33,11 +33,13 @@ import com.google.auto.common.MoreElements;
 import com.google.auto.common.MoreTypes;
 import com.google.auto.common.Visibility;
 import com.google.auto.service.AutoService;
+import com.google.auto.value.processor.BuilderSpec.PropertyGetter;
 import com.google.auto.value.processor.MissingTypes.MissingTypeException;
 import com.google.common.base.Ascii;
 import com.google.common.base.VerifyException;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
 import java.lang.reflect.Field;
 import java.util.List;
 import java.util.Map;
@@ -121,16 +123,19 @@ public class AutoBuilderProcessor extends AutoValueishProcessor {
     BuilderSpec builderSpec = new BuilderSpec(ofClass, processingEnv, errorReporter());
     BuilderSpec.Builder builder = builderSpec.new Builder(autoBuilderType);
     TypeMirror builtType = builtType(executable);
-    Optional<BuilderMethodClassifier<VariableElement>> classifier =
+    Optional<BuilderMethodClassifier<VariableElement>> maybeClassifier =
         BuilderMethodClassifierForAutoBuilder.classify(
             methods, errorReporter(), processingEnv, executable, builtType, autoBuilderType);
-    if (!classifier.isPresent()) {
+    if (!maybeClassifier.isPresent()) {
       // We've already output one or more error messages.
       return;
     }
+    BuilderMethodClassifier<VariableElement> classifier = maybeClassifier.get();
+    Map<String, String> propertyToGetterName =
+        Maps.transformValues(classifier.builderGetters(), PropertyGetter::getName);
     AutoBuilderTemplateVars vars = new AutoBuilderTemplateVars();
-    vars.props = propertySet(executable);
-    builder.defineVars(vars, classifier.get());
+    vars.props = propertySet(executable, propertyToGetterName);
+    builder.defineVars(vars, classifier);
     vars.identifiers = !processingEnv.getOptions().containsKey(OMIT_IDENTIFIERS_OPTION);
     String generatedClassName = generatedClassName(autoBuilderType, "AutoBuilder_");
     vars.builderName = TypeSimplifier.simpleNameOf(generatedClassName);
@@ -145,7 +150,8 @@ public class AutoBuilderProcessor extends AutoValueishProcessor {
     writeSourceFile(generatedClassName, text, autoBuilderType);
   }
 
-  private ImmutableSet<Property> propertySet(ExecutableElement executable) {
+  private ImmutableSet<Property> propertySet(
+      ExecutableElement executable, Map<String, String> propertyToGetterName) {
     // Fix any parameter names that are reserved words in Java. Java source code can't have
     // such parameter names, but Kotlin code might, for example.
     Map<VariableElement, String> identifiers =
@@ -153,14 +159,18 @@ public class AutoBuilderProcessor extends AutoValueishProcessor {
             .collect(toMap(v -> v, v -> v.getSimpleName().toString()));
     fixReservedIdentifiers(identifiers);
     return executable.getParameters().stream()
-        .map(v -> newProperty(v, identifiers.get(v)))
+        .map(
+            v ->
+                newProperty(
+                    v, identifiers.get(v), propertyToGetterName.get(v.getSimpleName().toString())))
         .collect(toImmutableSet());
   }
 
-  private Property newProperty(VariableElement var, String identifier) {
+  private Property newProperty(VariableElement var, String identifier, String getterName) {
     String name = var.getSimpleName().toString();
     TypeMirror type = var.asType();
-    return new Property(name, identifier, TypeEncoder.encode(type), type, Optional.empty());
+    return new Property(
+        name, identifier, TypeEncoder.encode(type), type, Optional.empty(), getterName);
   }
 
   private ExecutableElement findExecutable(
diff --git a/value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java b/value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java
index 20989f05..a494b9a6 100644
--- a/value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java
+++ b/value/src/main/java/com/google/auto/value/processor/AutoValueishProcessor.java
@@ -21,6 +21,7 @@ import static com.google.auto.common.MoreElements.getPackage;
 import static com.google.auto.common.MoreElements.isAnnotationPresent;
 import static com.google.auto.value.processor.ClassNames.AUTO_VALUE_PACKAGE_NAME;
 import static com.google.auto.value.processor.ClassNames.COPY_ANNOTATIONS_NAME;
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static com.google.common.collect.Iterables.getOnlyElement;
 import static com.google.common.collect.Sets.union;
 import static java.util.stream.Collectors.joining;
@@ -155,19 +156,22 @@ abstract class AutoValueishProcessor extends AbstractProcessor {
     private final TypeMirror typeMirror;
     private final Optional<String> nullableAnnotation;
     private final Optionalish optional;
+    private final String getter;
 
     Property(
         String name,
         String identifier,
         String type,
         TypeMirror typeMirror,
-        Optional<String> nullableAnnotation) {
+        Optional<String> nullableAnnotation,
+        String getter) {
       this.name = name;
       this.identifier = identifier;
       this.type = type;
       this.typeMirror = typeMirror;
       this.nullableAnnotation = nullableAnnotation;
       this.optional = Optionalish.createIfOptional(typeMirror);
+      this.getter = getter;
     }
 
     /**
@@ -227,6 +231,16 @@ abstract class AutoValueishProcessor extends AbstractProcessor {
     public boolean isNullable() {
       return nullableAnnotation.isPresent();
     }
+
+    /**
+     * Returns the name of the getter method for this property as defined by the {@code @AutoValue}
+     * or {@code @AutoBuilder} class. For property {@code foo}, this will be {@code foo} or {@code
+     * getFoo} or {@code isFoo}. For AutoValue, this will also be the name of a getter method in a
+     * builder; in the case of AutoBuilder it will only be that and may be null.
+     */
+    public String getGetter() {
+      return getter;
+    }
   }
 
   /** A {@link Property} that corresponds to an abstract getter method in the source. */
@@ -248,21 +262,14 @@ abstract class AutoValueishProcessor extends AbstractProcessor {
           identifier,
           type,
           method.getReturnType(),
-          nullableAnnotation);
+          nullableAnnotation,
+          method.getSimpleName().toString());
       this.method = method;
       this.fieldAnnotations = fieldAnnotations;
       this.methodAnnotations = methodAnnotations;
     }
 
     /**
-     * Returns the name of the getter method for this property as defined by the {@code @AutoValue}
-     * class. For property {@code foo}, this will be {@code foo} or {@code getFoo} or {@code isFoo}.
-     */
-    public String getGetter() {
-      return method.getSimpleName().toString();
-    }
-
-    /**
      * Returns the annotations (in string form) that should be applied to the property's field
      * declaration.
      */
@@ -604,21 +611,19 @@ abstract class AutoValueishProcessor extends AbstractProcessor {
    * includes {@code isFoo} methods if they return {@code boolean}. This corresponds to JavaBeans
    * conventions.
    */
-  static ImmutableSet<ExecutableElement> prefixedGettersIn(Iterable<ExecutableElement> methods) {
-    ImmutableSet.Builder<ExecutableElement> getters = ImmutableSet.builder();
-    for (ExecutableElement method : methods) {
-      String name = method.getSimpleName().toString();
-      // Note that getfoo() (without a capital) is still a getter.
-      boolean get = name.startsWith("get") && !name.equals("get");
-      boolean is =
-          name.startsWith("is")
-              && !name.equals("is")
-              && method.getReturnType().getKind() == TypeKind.BOOLEAN;
-      if (get || is) {
-        getters.add(method);
-      }
-    }
-    return getters.build();
+  static ImmutableSet<ExecutableElement> prefixedGettersIn(Collection<ExecutableElement> methods) {
+    return methods.stream()
+        .filter(AutoValueishProcessor::isPrefixedGetter)
+        .collect(toImmutableSet());
+  }
+
+  static boolean isPrefixedGetter(ExecutableElement method) {
+    String name = method.getSimpleName().toString();
+    // Note that getfoo() (without a capital) is still a getter.
+    return (name.startsWith("get") && !name.equals("get"))
+        || (name.startsWith("is")
+            && !name.equals("is")
+            && method.getReturnType().getKind() == TypeKind.BOOLEAN);
   }
 
   /**
diff --git a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java
index a40467dc..0bcaa682 100644
--- a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java
+++ b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java
@@ -234,15 +234,15 @@ abstract class BuilderMethodClassifier<E extends Element> {
    * ImmutableList<String> foos()} or {@code getFoos()}.
    */
   private void classifyMethodNoArgs(ExecutableElement method) {
-    String methodName = method.getSimpleName().toString();
-    TypeMirror returnType = builderMethodReturnType(method);
-
-    Optional<String> getterProperty = propertyForBuilderGetter(methodName);
+    Optional<String> getterProperty = propertyForBuilderGetter(method);
     if (getterProperty.isPresent()) {
       classifyGetter(method, getterProperty.get());
       return;
     }
 
+    String methodName = method.getSimpleName().toString();
+    TypeMirror returnType = builderMethodReturnType(method);
+
     if (methodName.endsWith("Builder")) {
       String property = methodName.substring(0, methodName.length() - "Builder".length());
       if (rewrittenPropertyTypes.containsKey(property)) {
@@ -683,12 +683,12 @@ abstract class BuilderMethodClassifier<E extends Element> {
   abstract String propertyString(E propertyElement);
 
   /**
-   * Returns the name of the property that a no-arg builder method of the given name queries, if
+   * Returns the name of the property that the given no-arg builder method queries, if
    * any. For example, if your {@code @AutoValue} class has a method {@code abstract String
    * getBar()} then an abstract method in its builder with the same signature will query the {@code
    * bar} property.
    */
-  abstract Optional<String> propertyForBuilderGetter(String methodName);
+  abstract Optional<String> propertyForBuilderGetter(ExecutableElement method);
 
   /**
    * Checks for failed JavaBean usage when a method that looks like a setter doesn't actually match
diff --git a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoBuilder.java b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoBuilder.java
index 16187de6..94b258f1 100644
--- a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoBuilder.java
+++ b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoBuilder.java
@@ -189,11 +189,24 @@ class BuilderMethodClassifierForAutoBuilder extends BuilderMethodClassifier<Vari
   }
 
   @Override
-  Optional<String> propertyForBuilderGetter(String methodName) {
-    // TODO: handle getFoo -> foo
-    return paramToPropertyName.containsValue(methodName)
-        ? Optional.of(methodName)
-        : Optional.empty();
+  Optional<String> propertyForBuilderGetter(ExecutableElement method) {
+    String methodName = method.getSimpleName().toString();
+    if (paramToPropertyName.containsValue(methodName)) {
+      return Optional.of(methodName);
+    }
+    if (AutoValueishProcessor.isPrefixedGetter(method)) {
+      int prefixLength = methodName.startsWith("get") ? 3 : 2; // "get" or "is"
+      String unprefixed = methodName.substring(prefixLength);
+      String propertyName = PropertyNames.decapitalizeLikeJavaBeans(unprefixed);
+      if (paramToPropertyName.containsValue(propertyName)) {
+        return Optional.of(propertyName);
+      }
+      propertyName = PropertyNames.decapitalizeNormally(unprefixed);
+      if (paramToPropertyName.containsValue(propertyName)) {
+        return Optional.of(propertyName);
+      }
+    }
+    return Optional.empty();
   }
 
   @Override
diff --git a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoValue.java b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoValue.java
index 39fa157d..dde449bb 100644
--- a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoValue.java
+++ b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifierForAutoValue.java
@@ -111,7 +111,8 @@ class BuilderMethodClassifierForAutoValue extends BuilderMethodClassifier<Execut
   }
 
   @Override
-  Optional<String> propertyForBuilderGetter(String methodName) {
+  Optional<String> propertyForBuilderGetter(ExecutableElement method) {
+    String methodName = method.getSimpleName().toString();
     return Optional.ofNullable(getterNameToGetter.get(methodName)).map(getterToPropertyName::get);
   }
 
diff --git a/value/src/main/java/com/google/auto/value/processor/BuilderSpec.java b/value/src/main/java/com/google/auto/value/processor/BuilderSpec.java
index 886b4d85..017a5ff5 100644
--- a/value/src/main/java/com/google/auto/value/processor/BuilderSpec.java
+++ b/value/src/main/java/com/google/auto/value/processor/BuilderSpec.java
@@ -354,6 +354,7 @@ class BuilderSpec {
    * five) then {@code Optional<T>} can be the corresponding boxed type.
    */
   public static class PropertyGetter {
+    private final String name;
     private final String access;
     private final String type;
     private final Optionalish optional;
@@ -371,11 +372,17 @@ class BuilderSpec {
      *     {@code Optional<T>} rather than {@code T}, as explained above.
      */
     PropertyGetter(ExecutableElement method, String type, Optionalish optional) {
+      this.name = method.getSimpleName().toString();
       this.access = SimpleMethod.access(method);
       this.type = type;
       this.optional = optional;
     }
 
+    // Not accessed from templates so doesn't have to be public.
+    String getName() {
+      return name;
+    }
+
     public String getAccess() {
       return access;
     }