/*
// Licensed to Julian Hyde under one or more contributor license
// agreements. See the NOTICE file distributed with this work for
// additional information regarding copyright ownership.
//
// Julian Hyde licenses this file to you 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 net.hydromatic.optiq.impl;
import net.hydromatic.optiq.Function;
import net.hydromatic.optiq.FunctionParameter;
import org.eigenbase.reltype.RelDataType;
import org.eigenbase.reltype.RelDataTypeFactory;
import com.google.common.collect.ImmutableList;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.List;
/**
* Implementation of a function that is based on a method.
* This class mainly solves conversion of method parameter types to {@code
* List<FunctionParameter>} form.
*/
public abstract class ReflectiveFunctionBase implements Function {
/** Method that implements the function. */
public final Method method;
/** Types of parameter for the function call. */
public final List<FunctionParameter> parameters;
/**
* {@code ReflectiveFunctionBase} constructor
* @param method method that is used to get type information from
*/
public ReflectiveFunctionBase(Method method) {
this.method = method;
this.parameters = toFunctionParameters(method.getParameterTypes());
}
/**
* Returns the parameters of this function.
*
* @return Parameters; never null
*/
public List<FunctionParameter> getParameters() {
return parameters;
}
public static ImmutableList<FunctionParameter> toFunctionParameters(
Class... types) {
return toFunctionParameters(Arrays.asList(types));
}
public static ImmutableList<FunctionParameter> toFunctionParameters(
Iterable<? extends Class> types) {
final ImmutableList.Builder<FunctionParameter> res =
ImmutableList.builder();
int i = 0;
for (final Class type : types) {
final int ordinal = i;
res.add(new FunctionParameter() {
public int getOrdinal() {
return ordinal;
}
public String getName() {
return "arg" + ordinal;
}
public RelDataType getType(RelDataTypeFactory typeFactory) {
return typeFactory.createJavaType(type);
}
});
i++;
}
return res.build();
}
/**
* Verifies if given class has public constructor with zero arguments.
* @param clazz class to verify
* @return true if given class has public constructor with zero arguments
*/
static boolean classHasPublicZeroArgsConstructor(Class<?> clazz) {
for (Constructor<?> constructor : clazz.getConstructors()) {
if (constructor.getParameterTypes().length == 0
&& (constructor.getModifiers() & Modifier.PUBLIC) != 0) {
return true;
}
}
return false;
}
/**
* Finds a method in a given class by name.
* @param clazz class to search method in
* @param name name of the method to find
* @return the first method with matching name or null when no method found
*/
static Method findMethod(Class<?> clazz, String name) {
for (Method method : clazz.getMethods()) {
if (method.getName().equals(name)) {
return method;
}
}
return null;
}
}
// End ReflectiveFunctionBase.java