Introduce MoreTypes utility class
#234
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| package tech.picnic.errorprone.bugpatterns.util; | ||||||
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| import static java.util.stream.Collectors.toCollection; | ||||||
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| import com.google.errorprone.VisitorState; | ||||||
| import com.google.errorprone.suppliers.Supplier; | ||||||
| import com.google.errorprone.suppliers.Suppliers; | ||||||
| import com.sun.tools.javac.code.BoundKind; | ||||||
| import com.sun.tools.javac.code.Type; | ||||||
| import java.util.ArrayList; | ||||||
| import java.util.Arrays; | ||||||
| import java.util.List; | ||||||
| import java.util.Objects; | ||||||
| import java.util.Optional; | ||||||
| import java.util.function.BiFunction; | ||||||
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| /** | ||||||
| * A set of helper methods which together define a DSL for defining {@link Type types}. | ||||||
| * | ||||||
| * <p>These methods are meant to be statically imported. Example usage: | ||||||
| * | ||||||
| * <pre>{@code | ||||||
| * Supplier<Type> type = | ||||||
| * VisitorState.memoize( | ||||||
| * generic( | ||||||
| * type("reactor.core.publisher.Flux"), | ||||||
| * subOf(generic(type("org.reactivestreams.Publisher"), unbound())))); | ||||||
| * }</pre> | ||||||
| * | ||||||
| * This statement produces a memoized supplier of the type {@code Flux<? extends Publisher<?>>}. | ||||||
| */ | ||||||
| public final class MoreTypes { | ||||||
| private MoreTypes() {} | ||||||
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| /** | ||||||
| * Creates a supplier of the type with the given fully qualified name. | ||||||
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There was a problem hiding this comment. Any reason for not using |
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| * | ||||||
| * <p>This method should only be used when building more complex types in combination with other | ||||||
| * {@link MoreTypes} methods. In other cases prefer directly calling {@link | ||||||
| * Suppliers#typeFromString(String)}. | ||||||
| * | ||||||
| * @param typeName The type of interest. | ||||||
| * @return A supplier which returns the described type if available in the given state, and {@code | ||||||
| * null} otherwise. | ||||||
| */ | ||||||
| public static Supplier<Type> type(String typeName) { | ||||||
| return Suppliers.typeFromString(typeName); | ||||||
| } | ||||||
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| /** | ||||||
| * Creates a supplier of the described generic type. | ||||||
| * | ||||||
| * @param type The base type of interest. | ||||||
| * @param typeArgs The desired type arguments. | ||||||
| * @return A supplier which returns the described type if available in the given state, and {@code | ||||||
| * null} otherwise. | ||||||
| */ | ||||||
| // XXX: The given `type` should be a generic type, so perhaps `withParams` would be a better | ||||||
| // method name. But the DSL wouldn't look as nice that way. | ||||||
| @SafeVarargs | ||||||
| @SuppressWarnings("varargs") | ||||||
| public static Supplier<Type> generic(Supplier<Type> type, Supplier<Type>... typeArgs) { | ||||||
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Suggested change
There was a problem hiding this comment. To me, I know
IMHO the DSL is very concise (even if we would make some of the method names a little longer). There was a problem hiding this comment.
In EP I see checks for this: Maybe it'd be nice to add a check for that in this method? Using There was a problem hiding this comment. I'm not yet feeling the first suggestion: in practice the code will look like There was a problem hiding this comment. W.r.t. the second suggestion: since the type evaluation is deferred, I'm not sure an |
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| return propagateNull( | ||||||
| type, | ||||||
| (state, baseType) -> { | ||||||
| List<Type> params = | ||||||
| Arrays.stream(typeArgs).map(s -> s.get(state)).collect(toCollection(ArrayList::new)); | ||||||
| if (params.stream().anyMatch(Objects::isNull)) { | ||||||
| return null; | ||||||
| } | ||||||
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| return state.getType(baseType, /* isArray= */ false, params); | ||||||
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There was a problem hiding this comment.
There was a problem hiding this comment. It's been a while since I wrote this, but indeed, I think |
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| }); | ||||||
| } | ||||||
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| /** | ||||||
| * Creates a raw (erased, non-generic) variant of the given type. | ||||||
| * | ||||||
| * @param type The base type of interest. | ||||||
| * @return A supplier which returns the described type if available in the given state, and {@code | ||||||
| * null} otherwise. | ||||||
| */ | ||||||
| public static Supplier<Type> raw(Supplier<Type> type) { | ||||||
| return propagateNull(type, (state, baseType) -> baseType.tsym.erasure(state.getTypes())); | ||||||
| } | ||||||
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| /** | ||||||
| * Creates a {@code ? super T} wildcard type, with {@code T} bound to the given type. | ||||||
| * | ||||||
| * @param type The base type of interest. | ||||||
| * @return A supplier which returns the described type if available in the given state, and {@code | ||||||
| * null} otherwise. | ||||||
| */ | ||||||
| public static Supplier<Type> superOf(Supplier<Type> type) { | ||||||
| return propagateNull( | ||||||
| type, | ||||||
| (state, baseType) -> | ||||||
| new Type.WildcardType(baseType, BoundKind.SUPER, state.getSymtab().boundClass)); | ||||||
| } | ||||||
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| /** | ||||||
| * Creates a {@code ? extends T} wildcard type, with {@code T} bound to the given type. | ||||||
| * | ||||||
| * @param type The base type of interest. | ||||||
| * @return A supplier which returns the described type if available in the given state, and {@code | ||||||
| * null} otherwise. | ||||||
| */ | ||||||
| public static Supplier<Type> subOf(Supplier<Type> type) { | ||||||
| return propagateNull( | ||||||
| type, | ||||||
| (state, baseType) -> | ||||||
| new Type.WildcardType( | ||||||
| type.get(state), BoundKind.EXTENDS, state.getSymtab().boundClass)); | ||||||
| } | ||||||
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| /** | ||||||
| * Creates an unbound wildcard type ({@code ?}). | ||||||
| * | ||||||
| * @return A supplier which returns the described type. | ||||||
| */ | ||||||
| public static Supplier<Type> unbound() { | ||||||
| return state -> | ||||||
| new Type.WildcardType( | ||||||
| state.getSymtab().objectType, BoundKind.UNBOUND, state.getSymtab().boundClass); | ||||||
| } | ||||||
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| private static Supplier<Type> propagateNull( | ||||||
| Supplier<Type> type, BiFunction<VisitorState, Type, Type> transformer) { | ||||||
| return state -> | ||||||
| Optional.ofNullable(type.get(state)).map(t -> transformer.apply(state, t)).orElse(null); | ||||||
| } | ||||||
| } | ||||||
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Let's add this class to
StaticImport.