src/com/google/inject/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;

import com.google.inject.internal.Errors;
import com.google.inject.internal.MatcherAndConverter;
import com.google.inject.internal.SourceProvider;
import com.google.inject.internal.Strings;
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 {@link Binder#convertToTypes} commands.
 *
 * @author crazybob@google.com (Bob Lee)
 * @author jessewilson@google.com (Jesse Wilson)
 */
class TypeConverterBindingProcessor extends AbstractProcessor {

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

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

      convertToClass(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(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(
        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<?>>";
          }
        }
      );
    } finally {
      this.injector = null;
    }
  }

  private <T> void convertToPrimitiveType(Class<T> primitiveType, final Class<T> wrapperType) {
    try {
      final Method parser = wrapperType.getMethod(
          "parse" + Strings.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(wrapperType, typeConverter);
    } catch (NoSuchMethodException e) {
      throw new AssertionError(e);
    }
  }

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

  private void convertToClasses(final Matcher<? super Class<?>> typeMatcher,
      TypeConverter converter) {
    internalConvertToTypes(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 void internalConvertToTypes(Matcher<? super TypeLiteral<?>> typeMatcher,
      TypeConverter converter) {
    injector.state.addConverter(
        new MatcherAndConverter(typeMatcher, converter, SourceProvider.UNKNOWN_SOURCE));
  }

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