// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or 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.twitter.common.args;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Set;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableSet;
import com.twitter.common.base.MorePreconditions;
/**
* Utilities for generating {@literal @CmdLine} {@link Arg} filters suitable for use with
* {@link com.twitter.common.args.ArgScanner#parse(Predicate, Iterable)}. These filters assume the
* fields parsed will all be annotated with {@link CmdLine}.
*
* @author John Sirois
*/
public final class ArgFilters {
/**
* A filter that selects all {@literal @CmdLine} {@link Arg}s found on the classpath.
*/
public static final Predicate<Field> SELECT_ALL = Predicates.alwaysTrue();
private ArgFilters() {
// utility
}
/**
* Creates a filter that selects all {@literal @CmdLine} {@link Arg}s found in classes that are
* members of the given package. Note that this will not select subpackages.
*
* @param pkg The exact package of classes whose command line args will be selected.
* @return A filter that selects only command line args declared in classes that are members of
* the given {@code pkg}.
*/
public static Predicate<Field> selectPackage(final Package pkg) {
Preconditions.checkNotNull(pkg);
return new Predicate<Field>() {
@Override public boolean apply(Field field) {
return field.getDeclaringClass().getPackage().equals(pkg);
}
};
}
/**
* Creates a filter that selects all {@literal @CmdLine} {@link Arg}s found in classes that are
* members of the given package or its sub-packages.
*
* @param pkg The ancestor package of classes whose command line args will be selected.
* @return A filter that selects only command line args declared in classes that are members of
* the given {@code pkg} or its sub-packages.
*/
public static Predicate<Field> selectAllPackagesUnderHere(final Package pkg) {
Preconditions.checkNotNull(pkg);
final String prefix = pkg.getName() + '.';
return Predicates.or(selectPackage(pkg), new Predicate<Field>() {
@Override public boolean apply(Field field) {
return field.getDeclaringClass().getPackage().getName().startsWith(prefix);
}
});
}
/**
* Creates a filter that selects all {@literal @CmdLine} {@link Arg}s found in the given class.
*
* @param clazz The class whose command line args will be selected.
* @return A filter that selects only command line args declared in the given {@code clazz}.
*/
public static Predicate<Field> selectClass(final Class<?> clazz) {
Preconditions.checkNotNull(clazz);
return new Predicate<Field>() {
@Override public boolean apply(Field field) {
return field.getDeclaringClass().equals(clazz);
}
};
}
/**
* Creates a filter that selects all {@literal @CmdLine} {@link Arg}s found in the given classes.
*
* @param cls The classes whose command line args will be selected.
* @return A filter that selects only command line args declared in the given classes.
*/
public static Predicate<Field> selectClasses(final Class<?> ... cls) {
Preconditions.checkNotNull(cls);
final Set<Class<?>> listOfClasses = ImmutableSet.copyOf(cls);
return new Predicate<Field>() {
@Override public boolean apply(Field field) {
return listOfClasses.contains(field.getDeclaringClass());
}
};
}
/**
* Creates a filter that selects all non-static {@literal @CmdLine} {@link Arg}s found in the
* given objects.
*
* @param obj The objects whose non-static command line args will be selected.
* @return A filter that selects only non-static command line args declared in the given objects.
*/
public static Predicate<Field> selectInstances(final Object ... obj) {
final Set<Object> setOfObjects = ImmutableSet.copyOf(obj);
return new Predicate<Field>() {
@Override public boolean apply(Field field) {
if (Modifier.isStatic(field.getModifiers())) {
return false;
}
for (Object o : setOfObjects) {
if (field.getDeclaringClass().isAssignableFrom(o.getClass())) {
return true;
}
}
return false;
}
};
}
/**
* Creates a filter that selects a single {@literal @CmdLine} {@link Arg}.
*
* @param clazz The class that declares the command line arg to be selected.
* @param name The {@link com.twitter.common.args.CmdLine#name()} of the arg to select.
* @return A filter that selects a single specified command line arg.
*/
public static Predicate<Field> selectCmdLineArg(Class<?> clazz, final String name) {
MorePreconditions.checkNotBlank(name);
return Predicates.and(selectClass(clazz), new Predicate<Field>() {
@Override public boolean apply(Field field) {
return field.getAnnotation(CmdLine.class).name().equals(name);
}
});
}
}