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/*
 * 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 io.trino.spi.function.table;

import io.trino.spi.Experimental;
import jakarta.annotation.Nullable;

import static io.trino.spi.function.table.Preconditions.checkArgument;
import static io.trino.spi.function.table.Preconditions.checkNotNullOrEmpty;

/**
 * Abstract class to capture the three supported argument types for a table function:
 * - Table arguments
 * - Descriptor arguments
 * - SQL scalar arguments
 * 
 * Each argument is named, and either passed positionally or in a `arg_name => value` convention.
 * 
 * Default values are allowed for all arguments except Table arguments.
 */
@Experimental(eta = "2022-10-31")
public abstract class ArgumentSpecification
{
    private final String name;
    private final boolean required;

    // native representation
    private final Object defaultValue;

    ArgumentSpecification(String name, boolean required, @Nullable Object defaultValue)
    {
        this.name = checkNotNullOrEmpty(name, "name");
        checkArgument(!required || defaultValue == null, "non-null default value for a required argument");
        this.required = required;
        this.defaultValue = defaultValue;
    }

    public String getName()
    {
        return name;
    }

    public boolean isRequired()
    {
        return required;
    }

    public Object getDefaultValue()
    {
        return defaultValue;
    }
}