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{}

}

func (s Select) MergeClause(clause *Clause) {
	if s.Expression != nil {
		if s.Distinct {
			if expr, ok := s.Expression.(Expr); ok {
				expr.SQL = "DISTINCT " + expr.SQL
				clause.Expression = expr
				return
			}
		}

		clause.Expression = s.Expression
	} else {
		clause.Expression = s
	}
}

// CommaExpression represents a group of expressions separated by commas.
type CommaExpression struct {

        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
     */

    /**
     * Interpolates all expressions in the src parameter.
     * <p>
     * The algorithm used for each expression is:
     * <ul>
     *   <li>If it starts with either "pom." or "project.", the expression is evaluated against the model.</li>
     *   <li>If the value is null, get the value from the context.</li>
     *   <li>If the value is null, but the context contains the expression, don't replace the expression string

        List<Expression> expressions = documentation.getExpressions();

        Map<String, Expression> bySyntax = new HashMap<>();

        if (expressions != null && !expressions.isEmpty()) {
            for (Expression expression : expressions) {
                bySyntax.put(expression.getSyntax(), expression);
            }
        }

        return bySyntax;
    }

            expressionsBySyntax = new java.util.HashMap();

            java.util.List expressions = getExpressions();

            if ( expressions != null && !expressions.isEmpty() )
            {
                for ( java.util.Iterator it = expressions.iterator(); it.hasNext(); )
                {
                    Expression expr = (Expression) it.next();

                    expressionsBySyntax.put( expr.getSyntax(), expr );

    <description> This is the MavenProject instance for the parent of the current POM.
    </description>
  </expression>
  <expression>
    <syntax>project.file</syntax>
    <description> This is the File instance that refers to the location of the current POM on
      disk.
    </description>
  </expression>
  <expression>
    <syntax>project.artifacts</syntax>
    <configuration>
      <![CDATA[
<dependencies>
  ...

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))

			},
			sql: "INNER JOIN `user` USING (`id`)",
		},
		{
			name: "Expression",
			join: clause.Join{
				// Invalid
				Type:  clause.LeftJoin,
				Table: clause.Table{Name: "user"},
				ON: clause.Where{
					Exprs: []clause.Expression{clause.Eq{clause.Column{Table: "user_info", Name: "user_id"}, clause.PrimaryColumn}},
				},
				// Valid
				Expression: clause.Join{
					Type:  clause.InnerJoin,

	column := "column-name"
	results := []struct {
		Expressions  []clause.Expression
		ExpectedVars []interface{}
		Result       string
	}{{
		Expressions: []clause.Expression{
			clause.Eq{Column: column, Value: "column-value"},
		},
		ExpectedVars: []interface{}{"column-value"},
		Result:       "`column-name` = ?",
	}, {
		Expressions: []clause.Expression{
			clause.Eq{Column: column, Value: nil},