ExpressionTrait.java

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

import org.apache.doris.nereids.annotation.Developing;
import org.apache.doris.nereids.exceptions.UnboundException;
import org.apache.doris.nereids.trees.TreeNode;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.types.DataType;

import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * ExpressionTrait.
 */
public interface ExpressionTrait extends TreeNode<Expression> {

    boolean nullable();

    default boolean notNullable() {
        return !nullable();
    }

    // check legality before do type coercion.
    // maybe we should merge checkInputDataTypes and checkLegality later.
    @Developing
    default void checkLegalityBeforeTypeCoercion() {}

    @Developing
    default void checkLegalityAfterRewrite() {}

    default List<Expression> getArguments() {
        return children();
    }

    default Expression getArgument(int index) {
        return child(index);
    }

    default List<DataType> getArgumentsTypes() {
        return getArguments()
                .stream()
                .map(Expression::getDataType)
                .collect(ImmutableList.toImmutableList());
    }

    default DataType getArgumentType(int index) {
        return child(index).getDataType();
    }

    default DataType getDataType() throws UnboundException {
        throw new UnboundException(toSql() + ".getDataType()");
    }

    default String toSql() throws UnboundException {
        throw new UnboundException("sql");
    }

    default boolean foldable() {
        return true;
    }

    /**
     * Identify the expression is containing non-foldable expr or not
     */
    default boolean containsNonfoldable() {
        return anyMatch(expr -> !((ExpressionTrait) expr).foldable());
    }

    /**
     * Identify the expression itself is deterministic or not, default true
     */
    default boolean isDeterministic() {
        return true;
    }

    /**
     * Identify the expression is containing non-deterministic expr or not
     */
    default boolean containsNondeterministic() {
        return anyMatch(expr -> !((ExpressionTrait) expr).isDeterministic());
    }
}