KeyExpression.java

/*-
 * #%L
 * JSQLParser library
 * %%
 * Copyright (C) 2004 - 2026 JSQLParser
 * %%
 * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
 * #L%
 */
package net.sf.jsqlparser.expression;

import java.util.Objects;
import net.sf.jsqlparser.parser.ASTNodeAccessImpl;

/**
 * Dialect specific expression for constructs such as {@code KEY chain.entity}.
 */
public class KeyExpression extends ASTNodeAccessImpl implements Expression {
    private final Expression expression;

    public KeyExpression(Expression expression) {
        this.expression = Objects.requireNonNull(expression,
                "The EXPRESSION of the KEY expression must not be null");
    }

    public Expression getExpression() {
        return expression;
    }

    @Override
    public <T, S> T accept(ExpressionVisitor<T> expressionVisitor, S context) {
        return expressionVisitor.visit(this, context);
    }

    public StringBuilder appendTo(StringBuilder builder) {
        builder.append("KEY ").append(expression);
        return builder;
    }

    @Override
    public String toString() {
        return appendTo(new StringBuilder()).toString();
    }
}