tools/processors/view_inspector/src/java/android/processor/view/inspector/InspectionCompanionGenerator.java - platform/frameworks/base - Gitiles

 /*
  * Copyright 2019 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package android.processor.view.inspector;

 import android.processor.view.inspector.InspectableClassModel.IntEnumEntry;
 import android.processor.view.inspector.InspectableClassModel.IntFlagEntry;
 import android.processor.view.inspector.InspectableClassModel.Property;

 import androidx.annotation.NonNull;

 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.CodeBlock;
 import com.squareup.javapoet.FieldSpec;
 import com.squareup.javapoet.JavaFile;
 import com.squareup.javapoet.MethodSpec;
 import com.squareup.javapoet.NameAllocator;
 import com.squareup.javapoet.ParameterizedTypeName;
 import com.squareup.javapoet.TypeName;
 import com.squareup.javapoet.TypeSpec;

 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.stream.Collectors;

 import javax.annotation.processing.Filer;
 import javax.lang.model.element.Modifier;

 /**
  * Generates a source file defining a {@link android.view.inspector.InspectionCompanion}.
  */
 public final class InspectionCompanionGenerator {
     private final @NonNull Filer mFiler;
     private final @NonNull Class mRequestingClass;

     /**
      * The class name for {@code R.java}.
      */
     private static final ClassName R_CLASS_NAME = ClassName.get("android", "R");

     /**
      * The class name of {@link android.view.inspector.InspectionCompanion}.
      */
     private static final ClassName INSPECTION_COMPANION = ClassName.get(
             "android.view.inspector", "InspectionCompanion");

     /**
      * The class name of {@link android.view.inspector.PropertyMapper}.
      */
     private static final ClassName PROPERTY_MAPPER = ClassName.get(
             "android.view.inspector", "PropertyMapper");

     /**
      * The class name of {@link android.view.inspector.PropertyReader}.
      */
     private static final ClassName PROPERTY_READER = ClassName.get(
             "android.view.inspector", "PropertyReader");

     /**
      * The class name of {@link android.util.SparseArray}.
      */
     private static final ClassName SPARSE_ARRAY = ClassName.get("android.util", "SparseArray");

     /**
      * The class name of {@link android.view.inspector.IntFlagMapping}.
      */
     private static final ClassName INT_FLAG_MAPPING = ClassName.get(
             "android.view.inspector", "IntFlagMapping");

     /**
      * The suffix of the generated class name after the class's binary name.
      */
     private static final String GENERATED_CLASS_SUFFIX = "$InspectionCompanion";

     /**
      * The null resource ID, copied to avoid a host dependency on platform code.
      *
      * @see android.content.res.Resources#ID_NULL
      */
     private static final int ID_NULL = 0;

     /**
      * @param filer A filer to write the generated source to
      * @param requestingClass A class object representing the class that invoked the generator
      */
     public InspectionCompanionGenerator(@NonNull Filer filer, @NonNull Class requestingClass) {
         mFiler = filer;
         mRequestingClass = requestingClass;
     }

     /**
      * Generate and write an inspection companion.
      *
      * @param model The model to generated
      * @throws IOException From the Filer
      */
     public void generate(@NonNull InspectableClassModel model) throws IOException {
         generateFile(model).writeTo(mFiler);
     }

     /**
      * Generate a {@link JavaFile} from a model.
      *
      * This is package-public for testing.
      *
      * @param model The model to generate from
      * @return A generated file of an {@link android.view.inspector.InspectionCompanion}
      */
     @NonNull
     JavaFile generateFile(@NonNull InspectableClassModel model) {
         return JavaFile
                 .builder(model.getClassName().packageName(), generateTypeSpec(model))
                 .indent("    ")
                 .build();
     }

     /**
      * Generate a {@link TypeSpec} for the {@link android.view.inspector.InspectionCompanion}
      * for the supplied model.
      *
      * @param model The model to generate from
      * @return A TypeSpec of the inspection companion
      */
     @NonNull
     private TypeSpec generateTypeSpec(@NonNull InspectableClassModel model) {
         final List<Property> properties = new ArrayList<>(model.getAllProperties());
         properties.sort(Comparator.comparing(Property::getName));

         final Map<Property, FieldSpec> fields = generateIdFieldSpecs(properties);

         TypeSpec.Builder builder = TypeSpec
                 .classBuilder(generateClassName(model))
                 .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
                 .addSuperinterface(ParameterizedTypeName.get(
                         INSPECTION_COMPANION, model.getClassName()))
                 .addJavadoc("Inspection companion for {@link $T}.\n\n", model.getClassName())
                 .addJavadoc("Generated by {@link $T}\n", getClass())
                 .addJavadoc("on behalf of {@link $T}.\n", mRequestingClass)
                 .addField(FieldSpec
                         .builder(TypeName.BOOLEAN, "mPropertiesMapped", Modifier.PRIVATE)
                         .initializer("false")
                         .addJavadoc("Guards against reading properties before mapping them.\n")
                         .build())
                 .addFields(properties.stream().map(fields::get).collect(Collectors.toList()))
                 .addMethod(generateMapProperties(properties, fields))
                 .addMethod(generateReadProperties(properties, fields, model.getClassName()));

         model.getNodeName().ifPresent(name -> builder.addMethod(generateGetNodeName(name)));

         return builder.build();
     }

     /**
      * Map properties to fields to store the mapping IDs in the generated inspection companion.
      *
      * @param properties A list of property models
      * @return A map of properties to their {@link FieldSpec}
      */
     @NonNull
     private Map<Property, FieldSpec> generateIdFieldSpecs(@NonNull List<Property> properties) {
         final Map<Property, FieldSpec> fields = new HashMap<>();
         final NameAllocator fieldNames = new NameAllocator();
         fieldNames.newName("mPropertiesMapped");

         for (Property property : properties) {
             final String memberName = fieldNames.newName(String.format(
                     "m%s%sId",
                     property.getName().substring(0, 1).toUpperCase(),
                     property.getName().substring(1)));

             fields.put(property, FieldSpec
                     .builder(TypeName.INT, memberName, Modifier.PRIVATE)
                     .addJavadoc("Property ID of {@code $L}.\n", property.getName())
                     .build());
         }

         return fields;
     }

     /**
      * Generates an implementation of
      * {@link android.view.inspector.InspectionCompanion#mapProperties(
      * android.view.inspector.PropertyMapper)}.
      *
      * Example:
      * <pre>
      *     @Override
      *     public void mapProperties(PropertyMapper propertyMapper) {
      *         mValueId = propertyMapper.mapInt("value", R.attr.value);
      *         mPropertiesMapped = true;
      *     }
      * </pre>
      *
      * @param properties A sorted list of property models
      * @param fields A map of properties to their ID field specs
      * @return A method definition
      */
     @NonNull
     private MethodSpec generateMapProperties(
             @NonNull List<Property> properties,
             @NonNull Map<Property, FieldSpec> fields) {
         final NameAllocator mappingVariables = new NameAllocator();

         final MethodSpec.Builder builder = MethodSpec.methodBuilder("mapProperties")
                 .addAnnotation(Override.class)
                 .addModifiers(Modifier.PUBLIC)
                 .addParameter(PROPERTY_MAPPER, "propertyMapper");

         // Reserve existing names
         mappingVariables.newName("mPropertiesMapped");
         mappingVariables.newName("propertyMapper");
         properties.forEach(p -> mappingVariables.newName(fields.get(p).name));

         for (Property property : properties) {
             final FieldSpec field = fields.get(property);
             switch (property.getType()) {
                 case INT_ENUM:
                     builder.addCode(generateIntEnumPropertyMapperInvocation(
                             property,
                             field,
                             mappingVariables.newName(property.getName() + "EnumMapping")));
                     break;
                 case INT_FLAG:
                     builder.addCode(generateIntFlagPropertyMapperInvocation(
                             property,
                             field,
                             mappingVariables.newName(property.getName() + "FlagMapping")));
                     break;
                 default:
                     builder.addCode(generateSimplePropertyMapperInvocation(property, field));
             }
         }

         builder.addStatement("mPropertiesMapped = true");

         return builder.build();
     }

     /**
      * Generate a {@link android.view.inspector.PropertyMapper} invocation.
      *
      * Example:
      * <pre>
      *     mValueId = propertyMapper.mapInt("value", R.attr.value);
      * </pre>
      *
      * @param property A property model to map
      * @param field The property ID field for the property
      * @return A code block containing a statement
      */
     @NonNull
     private CodeBlock generateSimplePropertyMapperInvocation(
             @NonNull Property property,
             @NonNull FieldSpec field) {
         return CodeBlock
                 .builder()
                 .addStatement(
                         "$N = propertyMapper.map$L($S, $L)",
                         field,
                         methodSuffixForPropertyType(property.getType()),
                         property.getName(),
                         generateAttributeId(property))
                 .build();
     }

     /**
      * Generate a {@link android.view.inspector.PropertyMapper} invocation for an int enum.
      *
      * Example:
      * <pre>
      *     final SparseArray<String> valueEnumMapping = new SparseArray<>();
      *     valueEnumMapping.put(1, "ONE");
      *     valueEnumMapping.put(2, "TWO");
      *     mValueId = propertyMapper.mapIntEnum("value", R.attr.value, valueEnumMapping::get);
      * </pre>
      *
      * @param property A property model to map
      * @param field The property ID field for the property
      * @param variable The name of a local variable to use to store the mapping in
      * @return A code block containing a series of statements
      */
     @NonNull
     private CodeBlock generateIntEnumPropertyMapperInvocation(
             @NonNull Property property,
             @NonNull FieldSpec field,
             @NonNull String variable) {
         final CodeBlock.Builder builder = CodeBlock.builder();

         final List<IntEnumEntry> enumEntries = property.getIntEnumEntries();
         enumEntries.sort(Comparator.comparing(IntEnumEntry::getValue));

         builder.addStatement(
                 "final $1T<$2T> $3N = new $1T<>()",
                 SPARSE_ARRAY,
                 String.class,
                 variable);

         for (IntEnumEntry enumEntry : enumEntries) {
             builder.addStatement(
                     "$N.put($L, $S)",
                     variable,
                     enumEntry.getValue(),
                     enumEntry.getName());
         }

         builder.addStatement(
                 "$N = propertyMapper.mapIntEnum($S, $L, $N::get)",
                 field,
                 property.getName(),
                 generateAttributeId(property),
                 variable);

         return builder.build();
     }

     /**
      * Generate a {@link android.view.inspector.PropertyMapper} invocation for an int flag.
      *
      * Example:
      * <pre>
      *     final IntFlagMapping valueFlagMapping = new IntFlagMapping();
      *     valueFlagMapping.add(0x00000003, 0x00000001, "ONE");
      *     valueFlagMapping.add(0x00000003, 0x00000002, "TWO");
      *     mValueId = propertyMapper.mapIntFlag("value", R.attr.value, valueFlagMapping::get);
      * </pre>
      *
      * @param property A property model to map
      * @param field The property ID field for the property
      * @param variable The name of a local variable to use to store the mapping in
      * @return A code block containing a series of statements
      */
     @NonNull
     private CodeBlock generateIntFlagPropertyMapperInvocation(
             @NonNull Property property,
             @NonNull FieldSpec field,
             @NonNull String variable) {
         final CodeBlock.Builder builder = CodeBlock.builder();

         final List<IntFlagEntry> flagEntries = property.getIntFlagEntries();
         flagEntries.sort(Comparator.comparing(IntFlagEntry::getName));

         builder.addStatement(
                 "final $1T $2N = new $1T()",
                 INT_FLAG_MAPPING,
                 variable);

         for (IntFlagEntry flagEntry : flagEntries) {
             builder.addStatement(
                     "$N.add($L, $L, $S)",
                     variable,
                     hexLiteral(flagEntry.getMask()),
                     hexLiteral(flagEntry.getTarget()),
                     flagEntry.getName());
         }

         builder.addStatement(
                 "$N = propertyMapper.mapIntFlag($S, $L, $N::get)",
                 field,
                 property.getName(),
                 generateAttributeId(property),
                 variable);

         return builder.build();
     }

     /**
      * Generate a literal attribute ID or reference to {@link android.R.attr}.
      *
      * Example: {@code R.attr.value} or {@code 0xdecafbad}.
      *
      * @param property A property model
      * @return A code block containing the attribute ID
      */
     @NonNull
     private CodeBlock generateAttributeId(@NonNull Property property) {
         if (property.isAttributeIdInferrableFromR()) {
             return CodeBlock.of("$T.attr.$L", R_CLASS_NAME, property.getName());
         } else {
             if (property.getAttributeId() == ID_NULL) {
                 return CodeBlock.of("$L", ID_NULL);
             } else {
                 return CodeBlock.of("$L", hexLiteral(property.getAttributeId()));
             }
         }
     }

     /**
      * Generate an implementation of
      * {@link android.view.inspector.InspectionCompanion#readProperties(Object,
      * android.view.inspector.PropertyReader)}.
      *
      * Example:
      * <pre>
      *     @Override
      *     public void readProperties(MyNode node, PropertyReader propertyReader) {
      *         if (!mPropertiesMapped) {
      *             throw new InspectionCompanion.UninitializedPropertyMapException();
      *         }
      *         propertyReader.readInt(mValueId, node.getValue());
      *     }
      * </pre>
      *
      * @param properties An ordered list of property models
      * @param fields A map from properties to their field specs
      * @param nodeClass The class of the node, used for the parameter type
      * @return A method definition
      */
     @NonNull
     private MethodSpec generateReadProperties(
             @NonNull List<Property> properties,
             @NonNull Map<Property, FieldSpec> fields,
             @NonNull ClassName nodeClass) {
         final MethodSpec.Builder builder =  MethodSpec.methodBuilder("readProperties")
                 .addAnnotation(Override.class)
                 .addModifiers(Modifier.PUBLIC)
                 .addParameter(nodeClass, "node")
                 .addParameter(PROPERTY_READER, "propertyReader")
                 .beginControlFlow("if (!mPropertiesMapped)")
                 .addStatement(
                         "throw new $T()",
                         INSPECTION_COMPANION.nestedClass("UninitializedPropertyMapException"))
                 .endControlFlow();

         for (Property property : properties) {
             builder.addStatement(
                     "propertyReader.read$L($N, node.$L)",
                     methodSuffixForPropertyType(property.getType()),
                     fields.get(property),
                     property.getAccessor().invocation());
         }

         return builder.build();
     }

     /**
      * Generate an implementation of
      * {@link android.view.inspector.InspectionCompanion#getNodeName()}.
      *
      * Example:
      * <pre>
      *     @Override
      *     public String getNodeName() {
      *         return "nodeName";
      *     }
      * </pre>
      *
      * @param nodeName The name of this node
      * @return A method definition that returns the node name
      */
     @NonNull
     private MethodSpec generateGetNodeName(@NonNull String nodeName) {
         return MethodSpec.methodBuilder("getNodeName")
                 .addAnnotation(Override.class)
                 .addModifiers(Modifier.PUBLIC)
                 .returns(String.class)
                 .addStatement("return $S", nodeName)
                 .build();
     }

     /**
      * Generate the final class name for the inspection companion from the model's class name.
      *
      * The generated class is added to the same package as the source class. If the class in the
      * model is a nested class, the nested class names are joined with {@code "$"}. The suffix
      * {@code "$InspectionCompanion"} is always added to the generated name. E.g.: For modeled
      * class {@code com.example.Outer.Inner}, the generated class name will be
      * {@code com.example.Outer$Inner$InspectionCompanion}.
      *
      * @param model The model to generate from
      * @return A class name for the generated inspection companion class
      */
     @NonNull
     private static ClassName generateClassName(@NonNull InspectableClassModel model) {
         final ClassName className = model.getClassName();

         return ClassName.get(
                 className.packageName(),
                 String.join("$", className.simpleNames()) + GENERATED_CLASS_SUFFIX);
     }

     /**
      * Get the suffix for a {@code map} or {@code read} method for a property type.
      *
      * @param type The requested property type
      * @return A method suffix
      */
     @NonNull
     private static String methodSuffixForPropertyType(@NonNull Property.Type type) {
         switch (type) {
             case BOOLEAN:
                 return "Boolean";
             case BYTE:
                 return "Byte";
             case CHAR:
                 return "Char";
             case DOUBLE:
                 return "Double";
             case FLOAT:
                 return "Float";
             case INT:
                 return "Int";
             case LONG:
                 return "Long";
             case SHORT:
                 return "Short";
             case OBJECT:
                 return "Object";
             case COLOR:
                 return "Color";
             case GRAVITY:
                 return "Gravity";
             case INT_ENUM:
                 return "IntEnum";
             case INT_FLAG:
                 return "IntFlag";
             case RESOURCE_ID:
                 return "ResourceId";
             default:
                 throw new NoSuchElementException(String.format("No such property type, %s", type));
         }
     }

     /**
      * Format an int as an 8 digit hex literal
      *
      * @param value The value to format
      * @return A string representation of the hex literal
      */
     @NonNull
     private static String hexLiteral(int value) {
         return String.format("0x%08x", value);
     }
 }
	/*
	* Copyright 2019 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package android.processor.view.inspector;

	import android.processor.view.inspector.InspectableClassModel.IntEnumEntry;
	import android.processor.view.inspector.InspectableClassModel.IntFlagEntry;
	import android.processor.view.inspector.InspectableClassModel.Property;

	import androidx.annotation.NonNull;

	import com.squareup.javapoet.ClassName;
	import com.squareup.javapoet.CodeBlock;
	import com.squareup.javapoet.FieldSpec;
	import com.squareup.javapoet.JavaFile;
	import com.squareup.javapoet.MethodSpec;
	import com.squareup.javapoet.NameAllocator;
	import com.squareup.javapoet.ParameterizedTypeName;
	import com.squareup.javapoet.TypeName;
	import com.squareup.javapoet.TypeSpec;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.Comparator;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.NoSuchElementException;
	import java.util.stream.Collectors;

	import javax.annotation.processing.Filer;
	import javax.lang.model.element.Modifier;

	/**
	* Generates a source file defining a {@link android.view.inspector.InspectionCompanion}.
	*/
	public final class InspectionCompanionGenerator {
	private final @NonNull Filer mFiler;
	private final @NonNull Class mRequestingClass;

	/**
	* The class name for {@code R.java}.
	*/
	private static final ClassName R_CLASS_NAME = ClassName.get("android", "R");

	/**
	* The class name of {@link android.view.inspector.InspectionCompanion}.
	*/
	private static final ClassName INSPECTION_COMPANION = ClassName.get(
	"android.view.inspector", "InspectionCompanion");

	/**
	* The class name of {@link android.view.inspector.PropertyMapper}.
	*/
	private static final ClassName PROPERTY_MAPPER = ClassName.get(
	"android.view.inspector", "PropertyMapper");

	/**
	* The class name of {@link android.view.inspector.PropertyReader}.
	*/
	private static final ClassName PROPERTY_READER = ClassName.get(
	"android.view.inspector", "PropertyReader");

	/**
	* The class name of {@link android.util.SparseArray}.
	*/
	private static final ClassName SPARSE_ARRAY = ClassName.get("android.util", "SparseArray");

	/**
	* The class name of {@link android.view.inspector.IntFlagMapping}.
	*/
	private static final ClassName INT_FLAG_MAPPING = ClassName.get(
	"android.view.inspector", "IntFlagMapping");

	/**
	* The suffix of the generated class name after the class's binary name.
	*/
	private static final String GENERATED_CLASS_SUFFIX = "$InspectionCompanion";

	/**
	* The null resource ID, copied to avoid a host dependency on platform code.
	*
	* @see android.content.res.Resources#ID_NULL
	*/
	private static final int ID_NULL = 0;

	/**
	* @param filer A filer to write the generated source to
	* @param requestingClass A class object representing the class that invoked the generator
	*/
	public InspectionCompanionGenerator(@NonNull Filer filer, @NonNull Class requestingClass) {
	mFiler = filer;
	mRequestingClass = requestingClass;
	}

	/**
	* Generate and write an inspection companion.
	*
	* @param model The model to generated
	* @throws IOException From the Filer
	*/
	public void generate(@NonNull InspectableClassModel model) throws IOException {
	generateFile(model).writeTo(mFiler);
	}

	/**
	* Generate a {@link JavaFile} from a model.
	*
	* This is package-public for testing.
	*
	* @param model The model to generate from
	* @return A generated file of an {@link android.view.inspector.InspectionCompanion}
	*/
	@NonNull
	JavaFile generateFile(@NonNull InspectableClassModel model) {
	return JavaFile
	.builder(model.getClassName().packageName(), generateTypeSpec(model))
	.indent(" ")
	.build();
	}

	/**
	* Generate a {@link TypeSpec} for the {@link android.view.inspector.InspectionCompanion}
	* for the supplied model.
	*
	* @param model The model to generate from
	* @return A TypeSpec of the inspection companion
	*/
	@NonNull
	private TypeSpec generateTypeSpec(@NonNull InspectableClassModel model) {
	final List<Property> properties = new ArrayList<>(model.getAllProperties());
	properties.sort(Comparator.comparing(Property::getName));

	final Map<Property, FieldSpec> fields = generateIdFieldSpecs(properties);

	TypeSpec.Builder builder = TypeSpec
	.classBuilder(generateClassName(model))
	.addModifiers(Modifier.PUBLIC, Modifier.FINAL)
	.addSuperinterface(ParameterizedTypeName.get(
	INSPECTION_COMPANION, model.getClassName()))
	.addJavadoc("Inspection companion for {@link $T}.\n\n", model.getClassName())
	.addJavadoc("Generated by {@link $T}\n", getClass())
	.addJavadoc("on behalf of {@link $T}.\n", mRequestingClass)
	.addField(FieldSpec
	.builder(TypeName.BOOLEAN, "mPropertiesMapped", Modifier.PRIVATE)
	.initializer("false")
	.addJavadoc("Guards against reading properties before mapping them.\n")
	.build())
	.addFields(properties.stream().map(fields::get).collect(Collectors.toList()))
	.addMethod(generateMapProperties(properties, fields))
	.addMethod(generateReadProperties(properties, fields, model.getClassName()));

	model.getNodeName().ifPresent(name -> builder.addMethod(generateGetNodeName(name)));

	return builder.build();
	}

	/**
	* Map properties to fields to store the mapping IDs in the generated inspection companion.
	*
	* @param properties A list of property models
	* @return A map of properties to their {@link FieldSpec}
	*/
	@NonNull
	private Map<Property, FieldSpec> generateIdFieldSpecs(@NonNull List<Property> properties) {
	final Map<Property, FieldSpec> fields = new HashMap<>();
	final NameAllocator fieldNames = new NameAllocator();
	fieldNames.newName("mPropertiesMapped");

	for (Property property : properties) {
	final String memberName = fieldNames.newName(String.format(
	"m%s%sId",
	property.getName().substring(0, 1).toUpperCase(),
	property.getName().substring(1)));

	fields.put(property, FieldSpec
	.builder(TypeName.INT, memberName, Modifier.PRIVATE)
	.addJavadoc("Property ID of {@code $L}.\n", property.getName())
	.build());
	}

	return fields;
	}

	/**
	* Generates an implementation of
	* {@link android.view.inspector.InspectionCompanion#mapProperties(
	* android.view.inspector.PropertyMapper)}.
	*
	* Example:
	* <pre>
	* @Override
	* public void mapProperties(PropertyMapper propertyMapper) {
	* mValueId = propertyMapper.mapInt("value", R.attr.value);
	* mPropertiesMapped = true;
	* }
	* </pre>
	*
	* @param properties A sorted list of property models
	* @param fields A map of properties to their ID field specs
	* @return A method definition
	*/
	@NonNull
	private MethodSpec generateMapProperties(
	@NonNull List<Property> properties,
	@NonNull Map<Property, FieldSpec> fields) {
	final NameAllocator mappingVariables = new NameAllocator();

	final MethodSpec.Builder builder = MethodSpec.methodBuilder("mapProperties")
	.addAnnotation(Override.class)
	.addModifiers(Modifier.PUBLIC)
	.addParameter(PROPERTY_MAPPER, "propertyMapper");

	// Reserve existing names
	mappingVariables.newName("mPropertiesMapped");
	mappingVariables.newName("propertyMapper");
	properties.forEach(p -> mappingVariables.newName(fields.get(p).name));

	for (Property property : properties) {
	final FieldSpec field = fields.get(property);
	switch (property.getType()) {
	case INT_ENUM:
	builder.addCode(generateIntEnumPropertyMapperInvocation(
	property,
	field,
	mappingVariables.newName(property.getName() + "EnumMapping")));
	break;
	case INT_FLAG:
	builder.addCode(generateIntFlagPropertyMapperInvocation(
	property,
	field,
	mappingVariables.newName(property.getName() + "FlagMapping")));
	break;
	default:
	builder.addCode(generateSimplePropertyMapperInvocation(property, field));
	}
	}

	builder.addStatement("mPropertiesMapped = true");

	return builder.build();
	}

	/**
	* Generate a {@link android.view.inspector.PropertyMapper} invocation.
	*
	* Example:
	* <pre>
	* mValueId = propertyMapper.mapInt("value", R.attr.value);
	* </pre>
	*
	* @param property A property model to map
	* @param field The property ID field for the property
	* @return A code block containing a statement
	*/
	@NonNull
	private CodeBlock generateSimplePropertyMapperInvocation(
	@NonNull Property property,
	@NonNull FieldSpec field) {
	return CodeBlock
	.builder()
	.addStatement(
	"$N = propertyMapper.map$L($S, $L)",
	field,
	methodSuffixForPropertyType(property.getType()),
	property.getName(),
	generateAttributeId(property))
	.build();
	}

	/**
	* Generate a {@link android.view.inspector.PropertyMapper} invocation for an int enum.
	*
	* Example:
	* <pre>
	* final SparseArray<String> valueEnumMapping = new SparseArray<>();
	* valueEnumMapping.put(1, "ONE");
	* valueEnumMapping.put(2, "TWO");
	* mValueId = propertyMapper.mapIntEnum("value", R.attr.value, valueEnumMapping::get);
	* </pre>
	*
	* @param property A property model to map
	* @param field The property ID field for the property
	* @param variable The name of a local variable to use to store the mapping in
	* @return A code block containing a series of statements
	*/
	@NonNull
	private CodeBlock generateIntEnumPropertyMapperInvocation(
	@NonNull Property property,
	@NonNull FieldSpec field,
	@NonNull String variable) {
	final CodeBlock.Builder builder = CodeBlock.builder();

	final List<IntEnumEntry> enumEntries = property.getIntEnumEntries();
	enumEntries.sort(Comparator.comparing(IntEnumEntry::getValue));

	builder.addStatement(
	"final $1T<$2T> $3N = new $1T<>()",
	SPARSE_ARRAY,
	String.class,
	variable);

	for (IntEnumEntry enumEntry : enumEntries) {
	builder.addStatement(
	"$N.put($L, $S)",
	variable,
	enumEntry.getValue(),
	enumEntry.getName());
	}

	builder.addStatement(
	"$N = propertyMapper.mapIntEnum($S, $L, $N::get)",
	field,
	property.getName(),
	generateAttributeId(property),
	variable);

	return builder.build();
	}

	/**
	* Generate a {@link android.view.inspector.PropertyMapper} invocation for an int flag.
	*
	* Example:
	* <pre>
	* final IntFlagMapping valueFlagMapping = new IntFlagMapping();
	* valueFlagMapping.add(0x00000003, 0x00000001, "ONE");
	* valueFlagMapping.add(0x00000003, 0x00000002, "TWO");
	* mValueId = propertyMapper.mapIntFlag("value", R.attr.value, valueFlagMapping::get);
	* </pre>
	*
	* @param property A property model to map
	* @param field The property ID field for the property
	* @param variable The name of a local variable to use to store the mapping in
	* @return A code block containing a series of statements
	*/
	@NonNull
	private CodeBlock generateIntFlagPropertyMapperInvocation(
	@NonNull Property property,
	@NonNull FieldSpec field,
	@NonNull String variable) {
	final CodeBlock.Builder builder = CodeBlock.builder();

	final List<IntFlagEntry> flagEntries = property.getIntFlagEntries();
	flagEntries.sort(Comparator.comparing(IntFlagEntry::getName));

	builder.addStatement(
	"final $1T $2N = new $1T()",
	INT_FLAG_MAPPING,
	variable);

	for (IntFlagEntry flagEntry : flagEntries) {
	builder.addStatement(
	"$N.add($L, $L, $S)",
	variable,
	hexLiteral(flagEntry.getMask()),
	hexLiteral(flagEntry.getTarget()),
	flagEntry.getName());
	}

	builder.addStatement(
	"$N = propertyMapper.mapIntFlag($S, $L, $N::get)",
	field,
	property.getName(),
	generateAttributeId(property),
	variable);

	return builder.build();
	}

	/**
	* Generate a literal attribute ID or reference to {@link android.R.attr}.
	*
	* Example: {@code R.attr.value} or {@code 0xdecafbad}.
	*
	* @param property A property model
	* @return A code block containing the attribute ID
	*/
	@NonNull
	private CodeBlock generateAttributeId(@NonNull Property property) {
	if (property.isAttributeIdInferrableFromR()) {
	return CodeBlock.of("$T.attr.$L", R_CLASS_NAME, property.getName());
	} else {
	if (property.getAttributeId() == ID_NULL) {
	return CodeBlock.of("$L", ID_NULL);
	} else {
	return CodeBlock.of("$L", hexLiteral(property.getAttributeId()));
	}
	}
	}

	/**
	* Generate an implementation of
	* {@link android.view.inspector.InspectionCompanion#readProperties(Object,
	* android.view.inspector.PropertyReader)}.
	*
	* Example:
	* <pre>
	* @Override
	* public void readProperties(MyNode node, PropertyReader propertyReader) {
	* if (!mPropertiesMapped) {
	* throw new InspectionCompanion.UninitializedPropertyMapException();
	* }
	* propertyReader.readInt(mValueId, node.getValue());
	* }
	* </pre>
	*
	* @param properties An ordered list of property models
	* @param fields A map from properties to their field specs
	* @param nodeClass The class of the node, used for the parameter type
	* @return A method definition
	*/
	@NonNull
	private MethodSpec generateReadProperties(
	@NonNull List<Property> properties,
	@NonNull Map<Property, FieldSpec> fields,
	@NonNull ClassName nodeClass) {
	final MethodSpec.Builder builder = MethodSpec.methodBuilder("readProperties")
	.addAnnotation(Override.class)
	.addModifiers(Modifier.PUBLIC)
	.addParameter(nodeClass, "node")
	.addParameter(PROPERTY_READER, "propertyReader")
	.beginControlFlow("if (!mPropertiesMapped)")
	.addStatement(
	"throw new $T()",
	INSPECTION_COMPANION.nestedClass("UninitializedPropertyMapException"))
	.endControlFlow();

	for (Property property : properties) {
	builder.addStatement(
	"propertyReader.read$L($N, node.$L)",
	methodSuffixForPropertyType(property.getType()),
	fields.get(property),
	property.getAccessor().invocation());
	}

	return builder.build();
	}

	/**
	* Generate an implementation of
	* {@link android.view.inspector.InspectionCompanion#getNodeName()}.
	*
	* Example:
	* <pre>
	* @Override
	* public String getNodeName() {
	* return "nodeName";
	* }
	* </pre>
	*
	* @param nodeName The name of this node
	* @return A method definition that returns the node name
	*/
	@NonNull
	private MethodSpec generateGetNodeName(@NonNull String nodeName) {
	return MethodSpec.methodBuilder("getNodeName")
	.addAnnotation(Override.class)
	.addModifiers(Modifier.PUBLIC)
	.returns(String.class)
	.addStatement("return $S", nodeName)
	.build();
	}

	/**
	* Generate the final class name for the inspection companion from the model's class name.
	*
	* The generated class is added to the same package as the source class. If the class in the
	* model is a nested class, the nested class names are joined with {@code "$"}. The suffix
	* {@code "$InspectionCompanion"} is always added to the generated name. E.g.: For modeled
	* class {@code com.example.Outer.Inner}, the generated class name will be
	* {@code com.example.Outer$Inner$InspectionCompanion}.
	*
	* @param model The model to generate from
	* @return A class name for the generated inspection companion class
	*/
	@NonNull
	private static ClassName generateClassName(@NonNull InspectableClassModel model) {
	final ClassName className = model.getClassName();

	return ClassName.get(
	className.packageName(),
	String.join("$", className.simpleNames()) + GENERATED_CLASS_SUFFIX);
	}

	/**
	* Get the suffix for a {@code map} or {@code read} method for a property type.
	*
	* @param type The requested property type
	* @return A method suffix
	*/
	@NonNull
	private static String methodSuffixForPropertyType(@NonNull Property.Type type) {
	switch (type) {
	case BOOLEAN:
	return "Boolean";
	case BYTE:
	return "Byte";
	case CHAR:
	return "Char";
	case DOUBLE:
	return "Double";
	case FLOAT:
	return "Float";
	case INT:
	return "Int";
	case LONG:
	return "Long";
	case SHORT:
	return "Short";
	case OBJECT:
	return "Object";
	case COLOR:
	return "Color";
	case GRAVITY:
	return "Gravity";
	case INT_ENUM:
	return "IntEnum";
	case INT_FLAG:
	return "IntFlag";
	case RESOURCE_ID:
	return "ResourceId";
	default:
	throw new NoSuchElementException(String.format("No such property type, %s", type));
	}
	}

	/**
	* Format an int as an 8 digit hex literal
	*
	* @param value The value to format
	* @return A string representation of the hex literal
	*/
	@NonNull
	private static String hexLiteral(int value) {
	return String.format("0x%08x", value);
	}
	}