Package com.google.errorprone.refaster

Class Refaster

java.lang.Object
com.google.errorprone.refaster.Refaster
public class Refaster extends Object
Static utilities to indicate special handling in Refaster templates.
Author:
lowasser@google.com (Louis Wasserman)

  • Method Summary

    Modifier and Type
    Method
    Description
    static <T> T
    anyOf(T... expressions)
    Indicates that Refaster should attempt to match a target expression against each of the specified template expressions, in order, and succeed at the first match.
    static <T> T[]
    asVarargs(T arg)
    Indicates that Refaster should treat this @Repeated argument specifically as a varargs argument.
    static <T> Class<T>
    clazz()
    This is a placeholder for the expression T.class.
    static void
    emitComment(String literal)
    This is a special method to emit a one-line comment.
    static <T> T
    emitCommentBefore(String literal, T expression)
    This is a special method to emit a comment before an expression.
    static <E extends Enum<E>>
    E
    enumValueOf(String string)
    This is a placeholder for the expression E.valueOf(string).
    static <T> boolean
    isInstance(Object o)
    This is a placeholder for the Java instanceof operator that can be used with Refaster type variables.
    static <T> T[]
    newArray(int size)
    This is a placeholder for new T[size].

    Methods inherited from class java.lang.Object

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

  • Method Details

    • asVarargs

      public static <T> T[] asVarargs(T arg)
      Indicates that Refaster should treat this @Repeated argument specifically as a varargs argument.

      For example, you might write 

      
 @BeforeTemplate void something(@Repeated T arg) {
  Stream.of(asVarargs(arg)); // doesn't use the Stream.of(T) overload, but Stream.of(T...)
 }

    • anyOf

      @SafeVarargs @CanIgnoreReturnValue public static <T> T anyOf(T... expressions)
      Indicates that Refaster should attempt to match a target expression against each of the specified template expressions, in order, and succeed at the first match.

      This method should only be used in Refaster templates, but should never actually be run.

      For example, instead of writing 

      
 @BeforeTemplate <E> List<E> copyOfSingleton(E element) {
   return ImmutableList.copyOf(Collections.singletonList(element));
 }
 @BeforeTemplate <E> List<E> copyOfArrayList(E element) {
   return ImmutableList.copyOf(Lists.newArrayList(element));
 }

      one could alternately write 

      
 @BeforeTemplate <E> List<E> singleton(E element) {
   return ImmutableList.copyOf(Refaster.anyOf(
     Collections.singletonList(element),
     Lists.newArrayList(element)));
 }

    • isInstance

      public static <T> boolean isInstance(Object o)
      This is a placeholder for the Java instanceof operator that can be used with Refaster type variables. The type argument must always be specified explicitly, e.g. Refaster.<String>isInstance(o).

      For example, instead of writing the broken 

      
 @AfterTemplate <T> boolean instanceOf(Object o) {
   return o instanceof T; // you want to match this, but it won't compile
 }

      you would instead write 

      
 @AfterTemplate <T> boolean instanceOf(Object o) {
   return Refaster.<T>isInstance(o); // generates the replacement "o instanceof T"
 }
      Throws:
      IllegalArgumentException - if T is not specified explicitly.

    • newArray

      public static <T> T[] newArray(int size)
      This is a placeholder for new T[size]. The type argument must always be specified explicitly, e.g. Refaster.<String>newArray(10).

      For example, instead of writing the broken 

      
 @AfterTemplate <T> T[] newTArray(int size) {
   return new T[size]; // you want to generate this code, but it won't compile
 }

      you would instead write 

      
 @AfterTemplate <T> T[] newTArray(int size) {
   return Refaster.<T>newArray(size);
 }
      Throws:
      IllegalArgumentException - if T is not specified explicitly.

    • clazz

      public static <T> Class<T> clazz()
      This is a placeholder for the expression T.class. The type argument must always be specified explicitly, e.g. Refaster.<String>clazz().

      For example, instead of writing the broken 

      
 @AfterTemplate <T> T[] getEnumConstants() {
   return T.class.getEnumConstants(); // you want to inline this, but it won't compile
 }
      you would instead write 
      
 @AfterTemplate <T> T[] getEnumConstants() {
   return Refaster.<T>clazz().getEnumConstants();
 }
      Throws:
      IllegalArgumentException - if T is not specified explicitly.

    • enumValueOf

      public static <E extends Enum<E>> E enumValueOf(String string)
      This is a placeholder for the expression E.valueOf(string). The type argument must always be specified explicitly, e.g. Refaster.<RoundingMode>valueOf(string).

      For example, instead of writing the broken 

      
 @BeforeTemplate <E extends Enum<E>> E valueOf(String str) {
   return E.valueOf(str);
 }

      you would instead write 

      
 @BeforeTemplate <E extends Enum<E>> E valueOf(String str) {
   return Refaster.<E>enumValueOf(str);
 }
      Throws:
      IllegalArgumentException - if E is not specified explicitly.

    • emitCommentBefore

      public static <T> T emitCommentBefore(String literal, T expression)
      This is a special method to emit a comment before an expression. The comment argument must always be a string literal. This method cannot be static imported.

      For example, instead of writing 

      
 @AfterTemplate int lengthWithComment(String str) {
   return /* comment \*\/ str.length();
 }

      you would instead write 

      
 @AfterTemplate int lengthWithComment(String str) {
   return Refaster.emitCommentBefore("comment", str.length());
 }

    • emitComment

      public static void emitComment(String literal)
      This is a special method to emit a one-line comment. The comment argument must always be a string literal. This method cannot be static imported.

      For example, instead of writing 

      
 @AfterTemplate void printWithComment(String str) {
   // comment
   System.out.println(str);
 }

      you would instead write 

      
 @AfterTemplate void printWithComment(String str) {
   Refaster.emitComment("comment");
   System.out.println(str);
 }