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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.sql.ir;

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.google.common.collect.ImmutableList;
import io.trino.spi.type.Type;
import io.trino.sql.planner.Symbol;
import io.trino.type.FunctionType;

import java.util.List;
import java.util.stream.Collectors;

import static com.google.common.collect.ImmutableList.toImmutableList;
import static io.trino.sql.ir.IrUtils.validateType;

/**
 * Bind(values, targetFunction)
 * 
 * When invoked, the returned function inserts the given values as
 * the leading arguments to the targetFunction.  The other arguments are
 * passed unchanged.
 * 

 * Bind is fundamentally first class, just like function applications.
 * It requires special treatment from the type system. There is no way
 * to write out the type of `bind`. The return type of `bind` is function.
 * Its type looks somewhat like:
 * 

 * X, (X) -> Y => () -> Y
 * 
X1, (X1, X2) -> Y => (X2) -> Y
 * 
X1, (X1, X2, X3) -> Y => (X2, X3) -> Y
 * 
X1, (X1, X2, X3, X4) -> Y => (X2, X3, X4) -> Y
 * 
...
 * 
 * 
 * Lambda capturing is implemented through desugaring in Trino.
 * This expression facilitates desugaring.
 */
@JsonSerialize
public record Bind(List values, Lambda function)
        implements Expression
{
    public Bind
    {
        values = ImmutableList.copyOf(values);
        for (int i = 0; i < values.size(); i++) {
            validateType(function.arguments().get(i).type(), values.get(i));
        }
    }

    @Override
    public Type type()
    {
        return new FunctionType(
                function.arguments()
                        .subList(values.size(), function.arguments().size()).stream()
                        .map(Symbol::type)
                        .collect(toImmutableList()),
                ((FunctionType) function.type()).getReturnType());
    }

    @Override
    public  R accept(IrVisitor visitor, C context)
    {
        return visitor.visitBind(this, context);
    }

    @Override
    public List children()
    {
        return ImmutableList.builder()
                .addAll(values)
                .add(function)
                .build();
    }

    @Override
    public String toString()
    {
        return "Bind(%s, %s)".formatted(
                function,
                values.stream()
                        .map(Expression::toString)
                        .collect(Collectors.joining(", ")));
    }
}