TryCast.java

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

import org.apache.doris.nereids.exceptions.UnboundException;
import org.apache.doris.nereids.trees.expressions.functions.AlwaysNullable;
import org.apache.doris.nereids.trees.expressions.functions.Monotonic;
import org.apache.doris.nereids.trees.expressions.shape.UnaryExpression;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.DataType;

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

import java.util.List;
import java.util.Objects;

/**
 * cast function.
 */
public class TryCast extends Cast implements UnaryExpression, Monotonic, AlwaysNullable {

    public TryCast(Expression child, DataType targetType) {
        this(child, targetType, false);
    }

    public TryCast(Expression child, DataType targetType, boolean isExplicitType) {
        this(ImmutableList.of(child), targetType, isExplicitType);
    }

    private TryCast(List<Expression> child, DataType targetType, boolean isExplicitType) {
        super(child, targetType, isExplicitType);
    }

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

    @Override
    public boolean nullable() {
        return true;
    }

    public boolean parentNullable() {
        return super.nullable();
    }

    @Override
    public TryCast withChildren(List<Expression> children) {
        Preconditions.checkArgument(children.size() == 1);
        return new TryCast(children, targetType, isExplicitType);
    }

    @Override
    public String computeToSql() throws UnboundException {
        return "tryCast(" + child().toSql() + " as " + targetType.toSql() + ")";
    }

    @Override
    public String toString() {
        return "tryCast(" + child() + " as " + targetType + ")";
    }

    @Override
    public boolean equals(Object o) {
        if (!super.equals(o)) {
            return false;
        }
        TryCast cast = (TryCast) o;
        return Objects.equals(targetType, cast.targetType);
    }

    @Override
    public int computeHashCode() {
        return Objects.hash(super.computeHashCode() + 1, targetType);
    }

    @Override
    public Expression withConstantArgs(Expression literal) {
        return new TryCast(literal, targetType, isExplicitType);
    }

}