/* * Copyright (C) 2009 The Guava Authors * * 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 org.jdbi.v3.core.generic.internal; import static java.util.Collections.emptyMap; import static java.util.Collections.unmodifiableMap; import static org.jdbi.v3.core.generic.internal.Preconditions.checkArgument; import static org.jdbi.v3.core.generic.internal.Preconditions.checkNotNull; import static org.jdbi.v3.core.generic.internal.Preconditions.checkState; import javax.annotation.Nullable; import java.lang.reflect.GenericArrayType; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.lang.reflect.TypeVariable; import java.lang.reflect.WildcardType; import java.util.Arrays; import java.util.HashMap; import java.util.LinkedHashMap; import java.util.Map; import java.util.Objects; import java.util.concurrent.atomic.AtomicInteger; import java.util.stream.Collectors; import java.util.stream.Stream; public final class TypeResolver { private final TypeTable typeTable; public TypeResolver() { this.typeTable = new TypeTable(); } private TypeResolver(TypeTable typeTable) { this.typeTable = typeTable; } static TypeResolver accordingTo(Type type) { return new TypeResolver().where(TypeMappingIntrospector.getTypeMappings(type)); } public TypeResolver where(Type formal, Type actual) { Map<TypeVariableKey, Type> mappings = new HashMap<>(); populateTypeMappings(mappings, checkNotNull(formal, "formal"), checkNotNull(actual, "actual")); return where(mappings); } TypeResolver where(Map<TypeVariableKey, ? extends Type> mappings) { return new TypeResolver(typeTable.where(mappings)); } private static void populateTypeMappings( final Map<TypeVariableKey, Type> mappings, Type from, final Type to) { if (from.equals(to)) { return; } new TypeVisitor() { @Override void visitTypeVariable(TypeVariable<?> typeVariable) { mappings.put(new TypeVariableKey(typeVariable), to); } @Override void visitWildcardType(WildcardType fromWildcardType) { if (!(to instanceof WildcardType)) { return; // okay to say <?> is anything } WildcardType toWildcardType = (WildcardType) to; Type[] fromUpperBounds = fromWildcardType.getUpperBounds(); Type[] toUpperBounds = toWildcardType.getUpperBounds(); Type[] fromLowerBounds = fromWildcardType.getLowerBounds(); Type[] toLowerBounds = toWildcardType.getLowerBounds(); checkArgument( fromUpperBounds.length == toUpperBounds.length && fromLowerBounds.length == toLowerBounds.length, "Incompatible type: %s vs. %s", fromWildcardType, to); for (int i = 0; i < fromUpperBounds.length; i++) { populateTypeMappings(mappings, fromUpperBounds[i], toUpperBounds[i]); } for (int i = 0; i < fromLowerBounds.length; i++) { populateTypeMappings(mappings, fromLowerBounds[i], toLowerBounds[i]); } } @Override void visitParameterizedType(ParameterizedType fromParameterizedType) { if (to instanceof WildcardType) { return; // Okay to say Foo<A> is <?> } ParameterizedType toParameterizedType = expectArgument(ParameterizedType.class, to); if (fromParameterizedType.getOwnerType() != null && toParameterizedType.getOwnerType() != null) { populateTypeMappings( mappings, fromParameterizedType.getOwnerType(), toParameterizedType.getOwnerType()); } checkArgument( fromParameterizedType.getRawType().equals(toParameterizedType.getRawType()), "Inconsistent raw type: %s vs. %s", fromParameterizedType, to); Type[] fromArgs = fromParameterizedType.getActualTypeArguments(); Type[] toArgs = toParameterizedType.getActualTypeArguments(); checkArgument( fromArgs.length == toArgs.length, "%s not compatible with %s", fromParameterizedType, toParameterizedType); for (int i = 0; i < fromArgs.length; i++) { populateTypeMappings(mappings, fromArgs[i], toArgs[i]); } } @Override void visitGenericArrayType(GenericArrayType fromArrayType) { if (to instanceof WildcardType) { return; // Okay to say A[] is <?> } Type componentType = Types.getComponentType(to); checkArgument(componentType != null, "%s is not an array type.", to); populateTypeMappings(mappings, fromArrayType.getGenericComponentType(), componentType); } @Override void visitClass(Class<?> fromClass) { if (to instanceof WildcardType) { return; // Okay to say Foo is <?> } // Can't map from a raw class to anything other than itself or a wildcard. // You can't say "assuming String is Integer". // And we don't support "assuming String is T"; user has to say "assuming T is String". throw new IllegalArgumentException("No type mapping from " + fromClass + " to " + to); } }.visit(from); } public Type resolveType(Type type) { checkNotNull(type, "type"); if (type instanceof TypeVariable) { return typeTable.resolve((TypeVariable<?>) type); } else if (type instanceof ParameterizedType) { return resolveParameterizedType((ParameterizedType) type); } else if (type instanceof GenericArrayType) { return resolveGenericArrayType((GenericArrayType) type); } else if (type instanceof WildcardType) { return resolveWildcardType((WildcardType) type); } else { // if Class<?>, no resolution needed, we are done. return type; } } private Type[] resolveTypes(Type[] types) { Type[] result = new Type[types.length]; for (int i = 0; i < types.length; i++) { result[i] = resolveType(types[i]); } return result; } private WildcardType resolveWildcardType(WildcardType type) { Type[] lowerBounds = type.getLowerBounds(); Type[] upperBounds = type.getUpperBounds(); return new Types.WildcardTypeImpl(resolveTypes(lowerBounds), resolveTypes(upperBounds)); } private Type resolveGenericArrayType(GenericArrayType type) { Type componentType = type.getGenericComponentType(); Type resolvedComponentType = resolveType(componentType); return Types.newArrayType(resolvedComponentType); } private ParameterizedType resolveParameterizedType(ParameterizedType type) { Type owner = type.getOwnerType(); Type resolvedOwner = (owner == null) ? null : resolveType(owner); Type resolvedRawType = resolveType(type.getRawType()); Type[] args = type.getActualTypeArguments(); Type[] resolvedArgs = resolveTypes(args); return Types.newParameterizedTypeWithOwner( resolvedOwner, (Class<?>) resolvedRawType, resolvedArgs); } private static <T> T expectArgument(Class<T> type, Object arg) { try { return type.cast(arg); } catch (ClassCastException e) { throw new IllegalArgumentException(arg + " is not a " + type.getSimpleName()); } } /** A TypeTable maintains mapping from {@link TypeVariable} to types. */ private static class TypeTable { private final Map<TypeVariableKey, Type> map; TypeTable() { this.map = emptyMap(); } private TypeTable(Map<TypeVariableKey, Type> map) { this.map = unmodifiableMap(new LinkedHashMap<>(map)); } /** Returns a new {@code TypeResolver} with {@code variable} mapping to {@code type}. */ final TypeTable where(Map<TypeVariableKey, ? extends Type> mappings) { Map<TypeVariableKey, Type> builder = new LinkedHashMap<>(); builder.putAll(map); for (Map.Entry<TypeVariableKey, ? extends Type> mapping : mappings.entrySet()) { TypeVariableKey variable = mapping.getKey(); Type type = mapping.getValue(); checkArgument(!variable.equalsType(type), "Type variable %s bound to itself", variable); builder.put(variable, type); } return new TypeTable(builder); } final Type resolve(final TypeVariable<?> var) { final TypeTable unguarded = this; TypeTable guarded = new TypeTable() { @Override public Type resolveInternal(TypeVariable<?> intermediateVar, TypeTable forDependent) { if (intermediateVar.getGenericDeclaration().equals(var.getGenericDeclaration())) { return intermediateVar; } return unguarded.resolveInternal(intermediateVar, forDependent); } }; return resolveInternal(var, guarded); } Type resolveInternal(TypeVariable<?> var, TypeTable forDependants) { Type type = map.get(new TypeVariableKey(var)); if (type == null) { Type[] bounds = var.getBounds(); if (bounds.length == 0) { return var; } Type[] resolvedBounds = new TypeResolver(forDependants).resolveTypes(bounds); if (Types.NativeTypeVariableEquals.NATIVE_TYPE_VARIABLE_ONLY && Arrays.equals(bounds, resolvedBounds)) { return var; } return Types.newArtificialTypeVariable( var.getGenericDeclaration(), var.getName(), resolvedBounds); } // in case the type is yet another type variable. return new TypeResolver(forDependants).resolveType(type); } } private static final class TypeMappingIntrospector extends TypeVisitor { private static final WildcardCapturer wildcardCapturer = new WildcardCapturer(); private final Map<TypeVariableKey, Type> mappings = new HashMap<>(); static Map<TypeVariableKey, Type> getTypeMappings(Type contextType) { TypeMappingIntrospector introspector = new TypeMappingIntrospector(); introspector.visit(wildcardCapturer.capture(contextType)); return unmodifiableMap(new LinkedHashMap<>(introspector.mappings)); } @Override void visitClass(Class<?> clazz) { visit(clazz.getGenericSuperclass()); visit(clazz.getGenericInterfaces()); } @Override void visitParameterizedType(ParameterizedType parameterizedType) { Class<?> rawClass = (Class<?>) parameterizedType.getRawType(); TypeVariable<?>[] vars = rawClass.getTypeParameters(); Type[] typeArgs = parameterizedType.getActualTypeArguments(); checkState(vars.length == typeArgs.length, "Expected %s type variables, but got %s", typeArgs.length, vars.length); for (int i = 0; i < vars.length; i++) { map(new TypeVariableKey(vars[i]), typeArgs[i]); } visit(rawClass); visit(parameterizedType.getOwnerType()); } @Override void visitTypeVariable(TypeVariable<?> t) { visit(t.getBounds()); } @Override void visitWildcardType(WildcardType t) { visit(t.getUpperBounds()); } private void map(final TypeVariableKey var, final Type arg) { if (mappings.containsKey(var)) { return; } for (Type t = arg; t != null; t = mappings.get(TypeVariableKey.forLookup(t))) { if (var.equalsType(t)) { for (Type x = arg; x != null; x = mappings.remove(TypeVariableKey.forLookup(x))) {} return; } } mappings.put(var, arg); } } private static final class WildcardCapturer { private final AtomicInteger id = new AtomicInteger(); Type capture(Type type) { checkNotNull(type, "type"); if (type instanceof Class) { return type; } if (type instanceof TypeVariable) { return type; } if (type instanceof GenericArrayType) { GenericArrayType arrayType = (GenericArrayType) type; return Types.newArrayType(capture(arrayType.getGenericComponentType())); } if (type instanceof ParameterizedType) { ParameterizedType parameterizedType = (ParameterizedType) type; return Types.newParameterizedTypeWithOwner( captureNullable(parameterizedType.getOwnerType()), (Class<?>) parameterizedType.getRawType(), capture(parameterizedType.getActualTypeArguments())); } if (type instanceof WildcardType) { WildcardType wildcardType = (WildcardType) type; Type[] lowerBounds = wildcardType.getLowerBounds(); if (lowerBounds.length == 0) { // ? extends something changes to capture-of Type[] upperBounds = wildcardType.getUpperBounds(); String name = "capture#" + id.incrementAndGet() + "-of ? extends " + Stream.of(upperBounds).map(Object::toString).collect(Collectors.joining("&")); return Types.newArtificialTypeVariable( WildcardCapturer.class, name, wildcardType.getUpperBounds()); } else { // TODO(benyu): handle ? super T somehow. return type; } } throw new AssertionError("must have been one of the known types"); } private Type captureNullable(@Nullable Type type) { if (type == null) { return null; } return capture(type); } private Type[] capture(Type[] types) { Type[] result = new Type[types.length]; for (int i = 0; i < types.length; i++) { result[i] = capture(types[i]); } return result; } } static final class TypeVariableKey { private final TypeVariable<?> var; TypeVariableKey(TypeVariable<?> var) { this.var = checkNotNull(var, "var"); } @Override public int hashCode() { return Objects.hash(var.getGenericDeclaration(), var.getName()); } @Override public boolean equals(Object obj) { if (obj instanceof TypeVariableKey) { TypeVariableKey that = (TypeVariableKey) obj; return equalsTypeVariable(that.var); } else { return false; } } @Override public String toString() { return var.toString(); } static TypeVariableKey forLookup(Type t) { if (t instanceof TypeVariable) { return new TypeVariableKey((TypeVariable<?>) t); } else { return null; } } boolean equalsType(Type type) { if (type instanceof TypeVariable) { return equalsTypeVariable((TypeVariable<?>) type); } else { return false; } } private boolean equalsTypeVariable(TypeVariable<?> that) { return var.getGenericDeclaration().equals(that.getGenericDeclaration()) && var.getName().equals(that.getName()); } } }