inject/internal/TypeConverterBindingProcessor.java

/**
 * Copyright (C) 2008 Google Inc.
 *
 * 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 com.google.inject.internal;

import com.google.inject.TypeLiteral;
import com.google.inject.internal.util.SourceProvider;
import com.google.inject.matcher.AbstractMatcher;
import com.google.inject.matcher.Matcher;
import com.google.inject.matcher.Matchers;
import com.google.inject.spi.TypeConverter;
import com.google.inject.spi.TypeConverterBinding;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;

/**
 * Handles {@code Binder.convertToTypes} commands.
 *
 * @author crazybob (at) google.com (Bob Lee)
 * @author jessewilson (at) google.com (Jesse Wilson)
 */
final class TypeConverterBindingProcessor extends AbstractProcessor {

  TypeConverterBindingProcessor(Errors errors) {
    super(errors);
  }

  /** Installs default converters for primitives, enums, and class literals. */
  static void prepareBuiltInConverters(InjectorImpl injector) {
    // Configure type converters.
    convertToPrimitiveType(injector, int.class, Integer.class);
    convertToPrimitiveType(injector, long.class, Long.class);
    convertToPrimitiveType(injector, boolean.class, Boolean.class);
    convertToPrimitiveType(injector, byte.class, Byte.class);
    convertToPrimitiveType(injector, short.class, Short.class);
    convertToPrimitiveType(injector, float.class, Float.class);
    convertToPrimitiveType(injector, double.class, Double.class);

    convertToClass(injector, Character.class, new TypeConverter() {
      public Object convert(String value, TypeLiteral<?> toType) {
        value = value.trim();
        if (value.length() != 1) {
          throw new RuntimeException("Length != 1.");
        }
        return value.charAt(0);
      }

      @Override public String toString() {
        return "TypeConverter<Character>";
      }
    });

    convertToClasses(injector, Matchers.subclassesOf(Enum.class), new TypeConverter() {
      @SuppressWarnings("unchecked")
      public Object convert(String value, TypeLiteral<?> toType) {
          return Enum.valueOf((Class) toType.getRawType(), value);
        }

        @Override public String toString() {
          return "TypeConverter<E extends Enum<E>>";
        }
      });

    internalConvertToTypes(injector, new AbstractMatcher<TypeLiteral<?>>() {
        public boolean matches(TypeLiteral<?> typeLiteral) {
          return typeLiteral.getRawType() == Class.class;
        }

        @Override public String toString() {
          return "Class<?>";
        }
      },
      new TypeConverter() {
        @SuppressWarnings("unchecked")
        public Object convert(String value, TypeLiteral<?> toType) {
          try {
            return Class.forName(value);
          } catch (ClassNotFoundException e) {
            throw new RuntimeException(e.getMessage());
          }
        }

        @Override public String toString() {
          return "TypeConverter<Class<?>>";
        }
      }
    );
  }

  private static <T> void convertToPrimitiveType(InjectorImpl injector, Class<T> primitiveType,
      final Class<T> wrapperType) {
    try {
      final Method parser = wrapperType.getMethod(
          "parse" + capitalize(primitiveType.getName()), String.class);

      TypeConverter typeConverter = new TypeConverter() {
        @SuppressWarnings("unchecked")
        public Object convert(String value, TypeLiteral<?> toType) {
          try {
            return parser.invoke(null, value);
          } catch (IllegalAccessException e) {
            throw new AssertionError(e);
          } catch (InvocationTargetException e) {
            throw new RuntimeException(e.getTargetException().getMessage());
          }
        }

        @Override public String toString() {
          return "TypeConverter<" + wrapperType.getSimpleName() + ">";
        }
      };

      convertToClass(injector, wrapperType, typeConverter);
    } catch (NoSuchMethodException e) {
      throw new AssertionError(e);
    }
  }

  private static <T> void convertToClass(InjectorImpl injector, Class<T> type,
      TypeConverter converter) {
    convertToClasses(injector, Matchers.identicalTo(type), converter);
  }

  private static void convertToClasses(InjectorImpl injector,
      final Matcher<? super Class<?>> typeMatcher, TypeConverter converter) {
    internalConvertToTypes(injector, new AbstractMatcher<TypeLiteral<?>>() {
      public boolean matches(TypeLiteral<?> typeLiteral) {
        Type type = typeLiteral.getType();
        if (!(type instanceof Class)) {
          return false;
        }
        Class<?> clazz = (Class<?>) type;
        return typeMatcher.matches(clazz);
      }

      @Override public String toString() {
        return typeMatcher.toString();
      }
    }, converter);
  }

  private static void internalConvertToTypes(InjectorImpl injector,
      Matcher<? super TypeLiteral<?>> typeMatcher,
      TypeConverter converter) {
    injector.state.addConverter(
        new TypeConverterBinding(SourceProvider.UNKNOWN_SOURCE, typeMatcher, converter));
  }

  @Override public Boolean visit(TypeConverterBinding command) {
    injector.state.addConverter(new TypeConverterBinding(
        command.getSource(), command.getTypeMatcher(), command.getTypeConverter()));
    return true;
  }

  private static String capitalize(String s) {
    if (s.length() == 0) {
      return s;
    }
    char first = s.charAt(0);
    char capitalized = Character.toUpperCase(first);
    return (first == capitalized)
        ? s
        : capitalized + s.substring(1);
  }

}