Class TypeEncoder

java.lang.Object

com.google.auto.value.processor.TypeEncoder

final class TypeEncoder
extends Object

Encodes types so they can later be decoded to incorporate imports.

The idea is that types that appear in generated source code use encode(TypeMirror), which will spell out a type like java.util.List<? extends java.lang.Number>, except that wherever a class name appears it is replaced by a special token. So the spelling might actually be `java.util.List`<? extends `java.lang.Number`>. Then once the entire class has been generated, #decode scans for these tokens to determine what classes need to be imported, and replaces the tokens with the correct spelling given the imports. So here, java.util.List would be imported, and the final spelling would be List<? extends Number> (knowing that Number is implicitly imported). The special token `import` marks where the imports should be, and decode(String, ProcessingEnvironment, String, TypeMirror) replaces it with the correct list of imports.

The funky syntax for type annotations on qualified type names requires an adjustment to this scheme. `«java.util.Map` stands for java.util. and `»java.util.Map` stands for Map. If java.util.Map is imported, then `«java.util.Map` will eventually be empty, but if java.util.Map is not imported (perhaps because there is another Map in scope) then `«java.util.Map` will be java.util.. The end result is that the code can contain `«java.util.Map`@`javax.annotation.Nullable` `»java.util.Map`. That might decode to @Nullable Map or to java.util.@Nullable Map or even to java.util.@javax.annotation.Nullable Map.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	TypeEncoder.AnnotatedEncodingTypeVisitor	Like TypeEncoder.EncodingTypeVisitor except that annotations on the visited type are also included in the resultant string.
private static class	TypeEncoder.EncodingTypeVisitor	Converts a type into a string, using standard Java syntax, except that every class name is wrapped in backquotes, like `java.util.List`.
private static class	TypeEncoder.RawEncodingTypeVisitor	Like TypeEncoder.EncodingTypeVisitor except that type parameters are omitted from the result.
private static class	TypeEncoder.TypeRewriter

Field Summary

Fields

Modifier and Type	Field	Description
private static final TypeEncoder.AnnotatedEncodingTypeVisitor	ANNOTATED_ENCODING_TYPE_VISITOR
private static final TypeEncoder.EncodingTypeVisitor	ENCODING_TYPE_VISITOR
private static final TypeEncoder.RawEncodingTypeVisitor	RAW_ENCODING_TYPE_VISITOR

Constructor Summary

Constructors

Modifier	Constructor	Description
private	TypeEncoder()

Method Summary

Modifier and Type	Method	Description
private static void	appendAnnotations(List<? extends AnnotationMirror> annotationMirrors, StringBuilder sb)
private static void	appendTypeParameterWithBounds(TypeParameterElement typeParameter, StringBuilder sb)
private static String	className(DeclaredType declaredType)
(package private) static String	decode(String text, ProcessingEnvironment processingEnv, String packageName, TypeMirror baseType)	Decodes the given string, respelling class names appropriately.
(package private) static String	decode(String text, Elements elementUtils, Types typeUtils, String pkg, TypeMirror baseType)
(package private) static String	encode(TypeMirror type)	Returns the encoding for the given type, where class names are marked by special tokens.
(package private) static String	encodeRaw(TypeMirror type)	Like encode(TypeMirror), except that only the raw type is encoded.
(package private) static String	encodeWithAnnotations(TypeMirror type)	Encodes the given type and its type annotations.
(package private) static String	formalTypeParametersString(TypeElement type)	Returns the formal type parameters of the given type.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

ENCODING_TYPE_VISITOR

private static final TypeEncoder.EncodingTypeVisitor ENCODING_TYPE_VISITOR

RAW_ENCODING_TYPE_VISITOR

private static final TypeEncoder.RawEncodingTypeVisitor RAW_ENCODING_TYPE_VISITOR

ANNOTATED_ENCODING_TYPE_VISITOR

private static final TypeEncoder.AnnotatedEncodingTypeVisitor ANNOTATED_ENCODING_TYPE_VISITOR

Constructor Details

TypeEncoder

private TypeEncoder()

Method Details

encode

static String encode(TypeMirror type)

Returns the encoding for the given type, where class names are marked by special tokens. The encoding for int will be int, but the encoding for java.util.List<java.lang.Integer> will be `java.util.List`<`java.lang.Integer`>.

encodeRaw

static String encodeRaw(TypeMirror type)

Like encode(TypeMirror), except that only the raw type is encoded. So if the given type is java.util.List<java.lang.Integer> the result will be `java.util.List`.

encodeWithAnnotations

static String encodeWithAnnotations(TypeMirror type)

Encodes the given type and its type annotations. The class comment for TypeEncoder covers the details of annotation encoding.

decode

static String decode(String text,
 ProcessingEnvironment processingEnv,
 String packageName,
 TypeMirror baseType)

Decodes the given string, respelling class names appropriately. The text is scanned for tokens like `java.util.Locale` or `«java.util.Locale` to determine which classes are referenced. An appropriate set of imports is computed based on the set of those types. If the special token `import` appears in text then it will be replaced by this set of import statements. Then all of the tokens are replaced by the class names they represent, spelled appropriately given the import statements.

Parameters:

text - the text to be decoded.

packageName - the package of the generated class. Other classes in the same package do not need to be imported.

baseType - a class or interface that the generated class inherits from. Nested classes in that type do not need to be imported, and if another class has the same name as one of those nested classes then it will need to be qualified.

decode

static String decode(String text,
 Elements elementUtils,
 Types typeUtils,
 String pkg,
 TypeMirror baseType)

className

private static String className(DeclaredType declaredType)

formalTypeParametersString

static String formalTypeParametersString(TypeElement type)

Returns the formal type parameters of the given type. If we have @AutoValue abstract class Foo<T extends SomeClass> then this method will return an encoding of <T extends SomeClass> for Foo. Likewise it will return an encoding of the angle-bracket part of:
Foo<SomeClass>
Foo<T extends Number>
Foo<E extends Enum<E>>
Foo<K, V extends Comparable<? extends K>>.

The encoding is simply that classes in the "extends" part are marked, so the examples will actually look something like this:
<`bar.baz.SomeClass`>
<T extends `java.lang.Number`>
<E extends `java.lang.Enum`<E>>
<K, V extends `java.lang.Comparable`<? extends K>>.

appendTypeParameterWithBounds

private static void appendTypeParameterWithBounds(TypeParameterElement typeParameter,
 StringBuilder sb)

appendAnnotations

private static void appendAnnotations(List<? extends AnnotationMirror> annotationMirrors,
 StringBuilder sb)