ArrayShuffle.java

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package org.apache.doris.nereids.trees.expressions.functions.scalar;

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.exceptions.AnalysisException;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.VolatileIdentity;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
import org.apache.doris.nereids.trees.expressions.shape.BinaryExpression;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.ArrayType;
import org.apache.doris.nereids.types.BigIntType;
import org.apache.doris.nereids.types.coercion.AnyDataType;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * ScalarFunction 'array_shuffle'
 *  with 1 or 2 arguments : array_shuffle(arr) or array_shuffle(arr, seed)
 */
public class ArrayShuffle extends UniqueFunction
        implements BinaryExpression, ExplicitlyCastableSignature, PropagateNullable {

    public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
            FunctionSignature.retArgType(0).args(ArrayType.of(new AnyDataType(0))),
            FunctionSignature.retArgType(0)
                    .args(ArrayType.of(new AnyDataType(0)), BigIntType.INSTANCE)
    );

    /**
     * constructor with 1 arguments.
     */
    public ArrayShuffle(Expression arg) {
        this(VolatileIdentity.newVolatileIdentity(), ImmutableList.of(arg));
    }

    /**
     * constructor with 2 arguments.
     */
    public ArrayShuffle(Expression arg, Expression arg1) {
        this(VolatileIdentity.newVolatileIdentity(), ImmutableList.of(arg, arg1));
    }

    private ArrayShuffle(VolatileIdentity volatileIdentity, List<Expression> children) {
        super("array_shuffle", volatileIdentity, children);
    }

    /** constructor for withChildren and reuse signature */
    private ArrayShuffle(UniqueFunctionParams functionParams) {
        super(functionParams);
    }

    /**
     * withChildren.
     */
    @Override
    public ArrayShuffle withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 1 || children.size() == 2);
        return new ArrayShuffle(getFunctionParams(children));
    }

    @Override
    public ArrayShuffle withIgnoreUniqueId(boolean ignoreUniqueId) {
        return new ArrayShuffle(volatileIdentity.withIgnoreUniqueId(ignoreUniqueId), children);
    }

    @Override
    public void checkLegalityBeforeTypeCoercion() {
        // The rows of a block draw from one random sequence that starts from the seed,
        // so a per-row seed would be ignored.
        if (arity() == 2 && !getArgument(1).isConstant()) {
            throw new AnalysisException("The seed of array_shuffle must be a constant: " + toSql());
        }
    }

    @Override
    public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
        return visitor.visitArrayShuffle(this, context);
    }

    @Override
    public List<FunctionSignature> getSignatures() {
        return SIGNATURES;
    }

}