import (
	"database/sql"
	"database/sql/driver"
	"go/ast"
	"reflect"
)

// Expression expression interface
type Expression interface {
	Build(builder Builder)
}

// NegationExpressionBuilder negation expression builder
type NegationExpressionBuilder interface {
	NegationBuild(builder Builder)
}

// Expr raw expression
type Expr struct {
	SQL                string
	Vars               []interface{}

@GwtCompatible
public final class Verify {
  /**
   * Ensures that {@code expression} is {@code true}, throwing a {@code VerifyException} with no
   * message otherwise.
   *
   * @throws VerifyException if {@code expression} is {@code false}
   * @see Preconditions#checkState Preconditions.checkState()
   */
  public static void verify(boolean expression) {
    if (!expression) {
      throw new VerifyException();
    }
  }

  /**

    static class Tokenizer {
        final String expression;

        int idx;

        Tokenizer(String expression) {
            this.expression = expression;
        }

        public int peekChar() {
            return idx < expression.length() ? expression.charAt(idx) : EOF;
        }

        public int skipChar() {
            return idx < expression.length() ? expression.charAt(idx++) : EOF;
        }

    }

    public void setValueOnModel(String expression, Object value) {
        context.setValue(expression, value);
    }

    public Iterator<?> getIteratorForXPathExpression(String expression) {
        return context.iterate(expression);
    }

    public boolean containsXPathExpression(String expression) {
        return context.getValue(expression) != null;
    }

	if !selectAST.Expression.All &&
		len(selectAST.Expression.Expressions) == 1 &&
		len(selectAST.Expression.Expressions[0].Expression.And) == 1 &&
		len(selectAST.Expression.Expressions[0].Expression.And[0].Condition) == 1 &&
		selectAST.Expression.Expressions[0].Expression.And[0].Condition[0].Operand != nil &&
		selectAST.Expression.Expressions[0].Expression.And[0].Condition[0].Operand.Operand.Left != nil &&

     *  @param expression A valid XPath string.
     *  @return A XPathNodes, should never be null.
     *
     * @throws XPathExpressionException if an XPath expression error occurs.
     */
    public XPathNodes selectNodeList(final Node contextNode, final String expression) throws XPathExpressionException {
        return xPath.evaluateExpression(expression, contextNode, XPathNodes.class);
    }

    /**

  @JvmName("-deprecated_url")
  @Deprecated(
    message = "moved to val",
    replaceWith = ReplaceWith(expression = "url"),
    level = DeprecationLevel.ERROR,
  )
  fun url(): HttpUrl = url

  @JvmName("-deprecated_dns")
  @Deprecated(
    message = "moved to val",
    replaceWith = ReplaceWith(expression = "dns"),
    level = DeprecationLevel.ERROR,
  )
  fun dns(): Dns = dns

        boostExpression = expression;
    }

    /**
     * Gets the current match expression.
     *
     * @return the match expression string
     */
    public String getMatchExpression() {
        return matchExpression;
    }

    /**
     * Sets the match expression used to determine if documents should be boosted.
     *
     * @param expression the match expression string
     */

type Join struct {
	Type       JoinType
	Table      Table
	ON         Where
	Using      []string
	Expression Expression
}

func JoinTable(names ...string) Table {
	return Table{
		Name: utils.JoinNestedRelationNames(names),
	}
}

func (join Join) Build(builder Builder) {
	if join.Expression != nil {
		join.Expression.Build(builder)
	} else {
		if join.Type != "" {
			builder.WriteString(string(join.Type))

     */
    @Override
    public Object getValue(String expression) {
        if (expression == null || expression.trim().isEmpty()) {
            return null;
        }

        try {
            return ReflectionValueExtractor.evaluate(expression, root, false);
        } catch (Exception e) {
            addFeedback("Failed to extract \'" + expression + "\' from: " + root, e);
        }

        return null;
    }