kr.ac.korea.dbserver.parser.SQLAnalyzer.java Source code

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kr.ac.korea.dbserver.parser;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import kr.ac.korea.dbserver.algebra.*;
import kr.ac.korea.dbserver.algebra.Aggregation.GroupType;
import kr.ac.korea.dbserver.algebra.CreateTable.*;
import kr.ac.korea.dbserver.algebra.LiteralValue.LiteralType;
import kr.ac.korea.dbserver.parser.SQLParser.*;
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.runtime.tree.TerminalNode;
import org.apache.commons.lang.StringEscapeUtils;
import org.apache.tajo.catalog.CatalogUtil;
import org.apache.tajo.common.TajoDataTypes.Type;
import org.apache.tajo.storage.StorageConstants;

import java.util.*;

import static kr.ac.korea.dbserver.algebra.Aggregation.GroupElement;
import static kr.ac.korea.dbserver.parser.SQLParser.*;

public class SQLAnalyzer extends SQLParserBaseVisitor<Expr> {
    private SQLParser parser;

    public SQLAnalyzer() {
    }

    public Expr parse(String sql) {
        ANTLRInputStream input = new ANTLRInputStream(sql);
        SQLLexer lexer = new SQLLexer(input);
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        this.parser = new SQLParser(tokens);
        parser.setBuildParseTree(true);
        parser.removeErrorListeners();

        parser.setErrorHandler(new SQLErrorStrategy());
        parser.addErrorListener(new SQLErrorListener());

        SqlContext context;
        try {
            context = parser.sql();
        } catch (SQLParseError e) {
            throw new SQLSyntaxError(e);
        }
        return visitSql(context);
    }

    private static boolean checkIfExist(Object obj) {
        return obj != null;
    }

    @Override
    public Expr visitSql(SqlContext ctx) {
        Expr statement = visit(ctx.statement());
        if (checkIfExist(ctx.explain_clause())) {
            return new Explain(statement);
        } else {
            return statement;
        }
    }

    @Override
    public Expr visitNon_join_query_expression(SQLParser.Non_join_query_expressionContext ctx) {

        Expr current = visitNon_join_query_term(ctx.non_join_query_term());
        if (ctx.getChildCount() == 1) {
            return current;
        }

        OpType operatorType;
        Expr left;
        for (int i = 1; i < ctx.getChildCount(); i++) {
            int idx = i;
            boolean distinct = true;

            if (ctx.getChild(idx) instanceof TerminalNode) {
                if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == UNION) {
                    operatorType = OpType.Union;
                } else {
                    operatorType = OpType.Except;
                }

                idx++;

                if (ctx.getChild(idx) instanceof TerminalNode) {
                    if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == ALL) {
                        distinct = false;
                    }

                    idx++;
                }

                SQLParser.Query_termContext queryTermContext = (SQLParser.Query_termContext) ctx.getChild(idx);
                Expr right = visitQuery_term(queryTermContext);

                left = current;
                current = new SetOperation(operatorType, left, right, distinct);

                i = idx;
            }
        }

        return current;
    }

    @Override
    public Expr visitNon_join_query_term(Non_join_query_termContext ctx) {

        Expr current = visitNon_join_query_primary(ctx.non_join_query_primary());
        Expr left;

        for (int i = 1; i < ctx.getChildCount();) {
            int idx = i;
            boolean distinct = true;

            if (ctx.getChild(idx) instanceof TerminalNode) {
                if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == INTERSECT) {
                    idx++;
                }

                if (ctx.getChild(idx) instanceof TerminalNode) {
                    if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == ALL) {
                        distinct = false;
                        idx++;
                    }
                }

                Query_primaryContext queryPrimaryContext = (Query_primaryContext) ctx.getChild(idx);
                Expr right = visitQuery_primary(queryPrimaryContext);

                left = current;
                current = new SetOperation(OpType.Intersect, left, right, distinct);

                i += idx;
            }
        }

        return current;

    }

    @Override
    public Expr visitQuery_specification(SQLParser.Query_specificationContext ctx) {
        Expr current = null;
        if (ctx.table_expression() != null) {
            current = visitFrom_clause(ctx.table_expression().from_clause());

            if (ctx.table_expression().where_clause() != null) {
                Selection selection = visitWhere_clause(ctx.table_expression().where_clause());
                selection.setChild(current);
                current = selection;
            }

            if (ctx.table_expression().groupby_clause() != null) {
                Aggregation aggregation = visitGroupby_clause(ctx.table_expression().groupby_clause());
                aggregation.setChild(current);
                current = aggregation;

                if (ctx.table_expression().having_clause() != null) {
                    Expr havingCondition = visitBoolean_value_expression(
                            ctx.table_expression().having_clause().boolean_value_expression());
                    Having having = new Having(havingCondition);
                    having.setChild(current);
                    current = having;
                }
            }

            if (ctx.table_expression().orderby_clause() != null) {
                Sort sort = visitOrderby_clause(ctx.table_expression().orderby_clause());
                sort.setChild(current);
                current = sort;
            }

            if (ctx.table_expression().limit_clause() != null) {
                Limit limit = visitLimit_clause(ctx.table_expression().limit_clause());
                limit.setChild(current);
                current = limit;
            }
        }

        Projection projection = visitSelect_list(ctx.select_list());

        if (ctx.set_qualifier() != null && ctx.set_qualifier().DISTINCT() != null) {
            projection.setDistinct();
        }

        if (current != null) {
            projection.setChild(current);
        }

        current = projection;

        return current;
    }

    /**
     * <pre>
     *   select_list
     *   : select_sublist (COMMA select_sublist)*
     *   ;
     * </pre>
     *
     * @param ctx
     * @return
     */
    @Override
    public Projection visitSelect_list(SQLParser.Select_listContext ctx) {
        Projection projection = new Projection();
        NamedExpr[] targets = new NamedExpr[ctx.select_sublist().size()];
        for (int i = 0; i < targets.length; i++) {
            targets[i] = visitSelect_sublist(ctx.select_sublist(i));
        }
        projection.setNamedExprs(targets);

        return projection;
    }

    /**
     * <pre>
     *   select_sublist
     *   : derived_column
     *   | asterisked_qualifier
     *   ;
     * </pre>
     *
     * @param ctx
     * @return
     */
    @Override
    public NamedExpr visitSelect_sublist(SQLParser.Select_sublistContext ctx) {
        if (ctx.qualified_asterisk() != null) {
            return visitQualified_asterisk(ctx.qualified_asterisk());
        } else {
            return visitDerived_column(ctx.derived_column());
        }
    }

    @Override
    public Expr visitFrom_target(From_targetContext ctx) {
        if (ctx.table_reference_list() != null) {
            return visitTable_reference_list(ctx.table_reference_list());
        } else {
            return visitDate_range_reference(ctx.date_range_reference());
        }
    }

    @Override
    public DateRangeRelations visitDate_range_reference(Date_range_referenceContext ctx) {
        return new DateRangeRelations(ctx.begin_date.getText(), ctx.end_date.getText());
    }

    @Override
    public RelationList visitTable_reference_list(Table_reference_listContext ctx) {
        Expr[] relations = new Expr[ctx.table_reference().size()];
        for (int i = 0; i < relations.length; i++) {
            relations[i] = visitTable_reference(ctx.table_reference(i));
        }
        return new RelationList(relations);
    }

    @Override
    public Selection visitWhere_clause(SQLParser.Where_clauseContext ctx) {
        return new Selection(visitSearch_condition(ctx.search_condition()));
    }

    @Override
    public Aggregation visitGroupby_clause(SQLParser.Groupby_clauseContext ctx) {
        Aggregation clause = new Aggregation();

        // If grouping group is not empty
        if (ctx.grouping_element_list().grouping_element().get(0).empty_grouping_set() == null) {
            int elementSize = ctx.grouping_element_list().grouping_element().size();
            ArrayList<GroupElement> groups = new ArrayList<GroupElement>(elementSize + 1);
            ArrayList<Expr> ordinaryExprs = null;
            int groupSize = 1;
            groups.add(null);

            for (int i = 0; i < elementSize; i++) {
                SQLParser.Grouping_elementContext element = ctx.grouping_element_list().grouping_element().get(i);
                if (element.ordinary_grouping_set() != null) {
                    if (ordinaryExprs == null) {
                        ordinaryExprs = new ArrayList<Expr>();
                    }
                    Collections.addAll(ordinaryExprs,
                            getRowValuePredicandsFromOrdinaryGroupingSet(element.ordinary_grouping_set()));
                } else if (element.rollup_list() != null) {
                    groupSize++;
                    groups.add(new GroupElement(GroupType.Rollup,
                            getRowValuePredicandsFromOrdinaryGroupingSetList(element.rollup_list().c)));
                } else if (element.cube_list() != null) {
                    groupSize++;
                    groups.add(new GroupElement(GroupType.Cube,
                            getRowValuePredicandsFromOrdinaryGroupingSetList(element.cube_list().c)));
                }
            }

            if (ordinaryExprs != null) {
                groups.set(0, new GroupElement(GroupType.OrdinaryGroup,
                        ordinaryExprs.toArray(new Expr[ordinaryExprs.size()])));
                clause.setGroups(groups.subList(0, groupSize).toArray(new GroupElement[groupSize]));
            } else if (groupSize > 1) {
                clause.setGroups(groups.subList(1, groupSize).toArray(new GroupElement[groupSize - 1]));
            }
        }

        return clause;
    }

    @Override
    public Sort visitOrderby_clause(SQLParser.Orderby_clauseContext ctx) {
        int size = ctx.sort_specifier_list().sort_specifier().size();
        Sort.SortSpec specs[] = new Sort.SortSpec[size];
        for (int i = 0; i < size; i++) {
            SQLParser.Sort_specifierContext specContext = ctx.sort_specifier_list().sort_specifier(i);
            Expr column = visitRow_value_predicand(specContext.key);
            specs[i] = new Sort.SortSpec(column);
            if (specContext.order_specification() != null) {
                if (specContext.order.DESC() != null) {
                    specs[i].setDescending();
                }
            }

            if (specContext.null_ordering() != null) {
                if (specContext.null_ordering().FIRST() != null) {
                    specs[i].setNullFirst();
                }
            }
        }

        return new Sort(specs);
    }

    @Override
    public Limit visitLimit_clause(SQLParser.Limit_clauseContext ctx) {
        return new Limit(visitNumeric_value_expression(ctx.numeric_value_expression()));
    }

    @Override
    public Expr visitJoined_table(SQLParser.Joined_tableContext ctx) {
        Expr top = visitTable_primary(ctx.table_primary());

        // The following loop builds a left deep join tree.
        Join join;
        for (int i = 0; i < ctx.joined_table_primary().size(); i++) {
            join = visitJoined_table_primary(ctx.joined_table_primary(i));
            join.setLeft(top);
            top = join;
        }

        return top;
    }

    @Override
    public Join visitJoined_table_primary(SQLParser.Joined_table_primaryContext ctx) {
        Join join;
        if (ctx.CROSS() != null) {
            join = new Join(JoinType.CROSS);
        } else if (ctx.UNION() != null) {
            join = new Join(JoinType.UNION);
        } else { // qualified join or natural
            if (ctx.join_type() != null && ctx.join_type().outer_join_type() != null) {
                Outer_join_type_part2Context outer_join_typeContext = ctx.join_type().outer_join_type()
                        .outer_join_type_part2();
                if (outer_join_typeContext.FULL() != null) {
                    join = new Join(JoinType.FULL_OUTER);
                } else if (outer_join_typeContext.LEFT() != null) {
                    join = new Join(JoinType.LEFT_OUTER);
                } else {
                    join = new Join(JoinType.RIGHT_OUTER);
                }
            } else {
                join = new Join(JoinType.INNER);
            }

            if (ctx.NATURAL() != null) {
                join.setNatural();
            }

            if (ctx.join_specification() != null) { // only for qualified join
                if (ctx.join_specification().join_condition() != null) {
                    Expr searchCondition = visitSearch_condition(
                            ctx.join_specification().join_condition().search_condition());
                    join.setQual(searchCondition);
                } else if (ctx.join_specification().named_columns_join() != null) {
                    ColumnReferenceExpr[] columns = getColumnReferences(
                            ctx.join_specification().named_columns_join().column_reference_list());
                    join.setJoinColumns(columns);
                }
            }
        }

        join.setRight(visitTable_primary(ctx.right));
        return join;
    }

    private Expr[] getRowValuePredicandsFromOrdinaryGroupingSetList(Ordinary_grouping_set_listContext ctx) {
        ArrayList<Expr> rowValuePredicands = new ArrayList<Expr>();
        for (int i = 0; i < ctx.ordinary_grouping_set().size(); i++) {
            Collections.addAll(rowValuePredicands,
                    getRowValuePredicandsFromOrdinaryGroupingSet(ctx.ordinary_grouping_set(i)));
        }
        return rowValuePredicands.toArray(new Expr[rowValuePredicands.size()]);
    }

    private Expr[] getRowValuePredicandsFromOrdinaryGroupingSet(Ordinary_grouping_setContext ctx) {
        ArrayList<Expr> rowValuePredicands = new ArrayList<Expr>();
        if (ctx.row_value_predicand() != null) {
            rowValuePredicands.add(visitRow_value_predicand(ctx.row_value_predicand()));
        }
        if (ctx.row_value_predicand_list() != null) {
            Collections.addAll(rowValuePredicands, getRowValuePredicands(ctx.row_value_predicand_list()));
        }
        return rowValuePredicands.toArray(new Expr[rowValuePredicands.size()]);
    }

    private Expr[] getRowValuePredicands(Row_value_predicand_listContext ctx) {
        Expr[] rowValuePredicands = new Expr[ctx.row_value_predicand().size()];
        for (int i = 0; i < rowValuePredicands.length; i++) {
            rowValuePredicands[i] = visitRow_value_predicand(ctx.row_value_predicand(i));
        }
        return rowValuePredicands;
    }

    private ColumnReferenceExpr[] getColumnReferences(Column_reference_listContext ctx) {
        ColumnReferenceExpr[] columnRefs = new ColumnReferenceExpr[ctx.column_reference().size()];
        for (int i = 0; i < columnRefs.length; i++) {
            columnRefs[i] = visitColumn_reference(ctx.column_reference(i));
        }
        return columnRefs;
    }

    @Override
    public Expr visitTable_primary(SQLParser.Table_primaryContext ctx) {
        if (ctx.table_or_query_name() != null) {
            Relation relation = new Relation(ctx.table_or_query_name().getText());
            if (ctx.alias != null) {
                relation.setAlias(ctx.alias.getText());
            }
            return relation;
        } else if (ctx.derived_table() != null) {
            return new TablePrimarySubQuery(ctx.name.getText(), visit(ctx.derived_table().table_subquery()));
        } else {
            return null;
        }
    }

    @Override
    public Expr visitSubquery(SQLParser.SubqueryContext ctx) {
        return visitQuery_expression(ctx.query_expression());
    }

    @Override
    public BetweenPredicate visitBetween_predicate(SQLParser.Between_predicateContext ctx) {
        Expr predicand = visitRow_value_predicand(ctx.predicand);
        Expr begin = visitRow_value_predicand(ctx.between_predicate_part_2().begin);
        Expr end = visitRow_value_predicand(ctx.between_predicate_part_2().end);
        return new BetweenPredicate(checkIfExist(ctx.between_predicate_part_2().NOT()),
                checkIfExist(ctx.between_predicate_part_2().SYMMETRIC()), predicand, begin, end);
    }

    @Override
    public CaseWhenPredicate visitSimple_case(SQLParser.Simple_caseContext ctx) {
        Expr leftTerm = visitBoolean_value_expression(ctx.boolean_value_expression());
        CaseWhenPredicate caseWhen = new CaseWhenPredicate();

        for (int i = 0; i < ctx.simple_when_clause().size(); i++) {
            Simple_when_clauseContext simpleWhenCtx = ctx.simple_when_clause(i);
            BinaryOperator bin = new BinaryOperator(OpType.Equals, leftTerm,
                    visitValue_expression(simpleWhenCtx.search_condition().value_expression()));
            caseWhen.addWhen(bin, buildCaseResult(simpleWhenCtx.result()));
        }
        if (ctx.else_clause() != null) {
            caseWhen.setElseResult(buildCaseResult(ctx.else_clause().result()));
        }
        return caseWhen;
    }

    private Expr buildCaseResult(ResultContext result) {
        if (result.NULL() != null) {
            return new NullLiteral();
        } else {
            return visitValue_expression(result.value_expression());
        }
    }

    @Override
    public CaseWhenPredicate visitSearched_case(SQLParser.Searched_caseContext ctx) {
        CaseWhenPredicate caseWhen = new CaseWhenPredicate();

        for (int i = 0; i < ctx.searched_when_clause().size(); i++) {
            Searched_when_clauseContext searchedWhenCtx = ctx.searched_when_clause(i);
            caseWhen.addWhen(visitSearch_condition(searchedWhenCtx.search_condition()),
                    buildCaseResult(searchedWhenCtx.result()));
        }
        if (ctx.else_clause() != null) {
            caseWhen.setElseResult(buildCaseResult(ctx.else_clause().result()));
        }
        return caseWhen;
    }

    @Override
    public Expr visitCommon_value_expression(SQLParser.Common_value_expressionContext ctx) {
        if (checkIfExist(ctx.NULL())) {
            return new NullLiteral();
        } else {
            return visitChildren(ctx);
        }
    }

    @Override
    public Expr visitParenthesized_value_expression(SQLParser.Parenthesized_value_expressionContext ctx) {
        return visitValue_expression(ctx.value_expression());
    }

    @Override
    public Expr visitBoolean_value_expression(SQLParser.Boolean_value_expressionContext ctx) {
        Expr current = visitOr_predicate(ctx.or_predicate());
        return current;
    }

    @Override
    public Expr visitOr_predicate(SQLParser.Or_predicateContext ctx) {
        Expr current = visitAnd_predicate(ctx.and_predicate());

        Expr left;
        Expr right;
        for (int i = 0; i < ctx.or_predicate().size(); i++) {
            left = current;
            right = visitOr_predicate(ctx.or_predicate(i));
            current = new BinaryOperator(OpType.Or, left, right);
        }

        return current;
    }

    @Override
    public Expr visitAnd_predicate(SQLParser.And_predicateContext ctx) {
        Expr current = visitBoolean_factor(ctx.boolean_factor());

        Expr left;
        Expr right;
        for (int i = 0; i < ctx.and_predicate().size(); i++) {
            left = current;
            right = visitAnd_predicate(ctx.and_predicate(i));
            current = new BinaryOperator(OpType.And, left, right);
        }

        return current;
    }

    @Override
    public Expr visitBoolean_factor(SQLParser.Boolean_factorContext ctx) {
        if (ctx.NOT() != null) {
            return new NotExpr(visitBoolean_test(ctx.boolean_test()));
        } else {
            return visitBoolean_test(ctx.boolean_test());
        }
    }

    @Override
    public Expr visitBoolean_test(SQLParser.Boolean_testContext ctx) {
        if (checkIfExist(ctx.is_clause())) {
            Is_clauseContext isClauseContext = ctx.is_clause();
            if (checkIfExist(isClauseContext.NOT())) {
                if (checkIfExist(ctx.is_clause().truth_value().TRUE())) {
                    return new NotExpr(visitBoolean_primary(ctx.boolean_primary()));
                } else {
                    return visitBoolean_primary(ctx.boolean_primary());
                }
            } else {
                if (checkIfExist(ctx.is_clause().truth_value().TRUE())) {
                    return visitBoolean_primary(ctx.boolean_primary());
                } else {
                    return new NotExpr(visitBoolean_primary(ctx.boolean_primary()));
                }
            }
        } else {
            return visitBoolean_primary(ctx.boolean_primary());
        }
    }

    @Override
    public Expr visitBoolean_primary(SQLParser.Boolean_primaryContext ctx) {
        if (ctx.predicate() != null) {
            return visitPredicate(ctx.predicate());
        } else {
            return visitBoolean_predicand(ctx.boolean_predicand());
        }
    }

    @Override
    public Expr visitBoolean_predicand(SQLParser.Boolean_predicandContext ctx) {
        if (checkIfExist(ctx.nonparenthesized_value_expression_primary())) {
            return visitNonparenthesized_value_expression_primary(ctx.nonparenthesized_value_expression_primary());
        } else {
            return visitBoolean_value_expression(
                    ctx.parenthesized_boolean_value_expression().boolean_value_expression());
        }
    }

    @Override
    public Expr visitNonparenthesized_value_expression_primary(
            SQLParser.Nonparenthesized_value_expression_primaryContext ctx) {
        return visitChildren(ctx);
    }

    @Override
    public Expr visitRow_value_predicand(SQLParser.Row_value_predicandContext ctx) {
        if (checkIfExist(ctx.row_value_special_case())) {
            return visitRow_value_special_case(ctx.row_value_special_case());
        } else {
            return visitRow_value_constructor_predicand(ctx.row_value_constructor_predicand());
        }
    }

    @Override
    public Expr visitRow_value_constructor_predicand(SQLParser.Row_value_constructor_predicandContext ctx) {
        if (checkIfExist(ctx.boolean_predicand())) {
            return visitBoolean_predicand(ctx.boolean_predicand());
        } else {
            return visitCommon_value_expression(ctx.common_value_expression());
        }
    }

    @Override
    public BinaryOperator visitComparison_predicate(SQLParser.Comparison_predicateContext ctx) {
        TerminalNode operator = (TerminalNode) ctx.comp_op().getChild(0);
        return new BinaryOperator(tokenToExprType(operator.getSymbol().getType()),
                visitRow_value_predicand(ctx.left), visitRow_value_predicand(ctx.right));
    }

    @Override
    public Expr visitNumeric_value_expression(SQLParser.Numeric_value_expressionContext ctx) {
        Expr current = visitTerm(ctx.term(0));

        Expr left;
        Expr right;
        for (int i = 1; i < ctx.getChildCount(); i++) {
            left = current;
            TerminalNode operator = (TerminalNode) ctx.getChild(i++);
            right = visitTerm((TermContext) ctx.getChild(i));

            if (operator.getSymbol().getType() == PLUS) {
                current = new BinaryOperator(OpType.Plus, left, right);
            } else {
                current = new BinaryOperator(OpType.Minus, left, right);
            }
        }

        return current;
    }

    @Override
    public Expr visitTerm(SQLParser.TermContext ctx) {
        Expr current = visitFactor(ctx.factor(0));

        Expr left;
        Expr right;
        for (int i = 1; i < ctx.getChildCount(); i++) {
            left = current;
            TerminalNode operator = (TerminalNode) ctx.getChild(i++);
            right = visitFactor((FactorContext) ctx.getChild(i));

            if (operator.getSymbol().getType() == MULTIPLY) {
                current = new BinaryOperator(OpType.Multiply, left, right);
            } else if (operator.getSymbol().getType() == DIVIDE) {
                current = new BinaryOperator(OpType.Divide, left, right);
            } else {
                current = new BinaryOperator(OpType.Modular, left, right);
            }
        }

        return current;
    }

    @Override
    public Expr visitFactor(SQLParser.FactorContext ctx) {
        Expr current = visitNumeric_primary(ctx.numeric_primary());
        if (checkIfExist(ctx.sign()) && checkIfExist(ctx.sign().MINUS())) {
            current = new SignedExpr(true, current);
        }
        return current;
    }

    @Override
    public Expr visitNumeric_primary(SQLParser.Numeric_primaryContext ctx) {
        Expr current = null;
        if (checkIfExist(ctx.value_expression_primary())) {
            current = visitValue_expression_primary(ctx.value_expression_primary());
            for (int i = 0; i < ctx.CAST_EXPRESSION().size(); i++) {
                current = new CastExpr(current, visitData_type(ctx.cast_target(i).data_type()));
            }
        } else if (checkIfExist(ctx.numeric_value_function())) {
            current = visitNumeric_value_function(ctx.numeric_value_function());
        }

        return current;
    }

    public static OpType tokenToExprType(int tokenId) {
        switch (tokenId) {
        case SQLParser.UNION:
            return OpType.Union;
        case SQLParser.EXCEPT:
            return OpType.Except;
        case SQLParser.INTERSECT:
            return OpType.Intersect;

        case SQLParser.AND:
            return OpType.And;
        case SQLParser.OR:
            return OpType.Or;

        case SQLParser.EQUAL:
            return OpType.Equals;
        case SQLParser.NOT_EQUAL:
            return OpType.NotEquals;
        case SQLParser.LTH:
            return OpType.LessThan;
        case SQLParser.LEQ:
            return OpType.LessThanOrEquals;
        case SQLParser.GTH:
            return OpType.GreaterThan;
        case SQLParser.GEQ:
            return OpType.GreaterThanOrEquals;

        case SQLParser.MULTIPLY:
            return OpType.Multiply;
        case SQLParser.DIVIDE:
            return OpType.Divide;
        case SQLParser.MODULAR:
            return OpType.Modular;
        case SQLParser.PLUS:
            return OpType.Plus;
        case SQLParser.MINUS:
            return OpType.Minus;

        default:
            throw new RuntimeException("Unknown Token Id: " + tokenId);
        }
    }

    @Override
    public InPredicate visitIn_predicate(SQLParser.In_predicateContext ctx) {
        return new InPredicate(visitChildren(ctx.numeric_value_expression()),
                visitIn_predicate_value(ctx.in_predicate_value()), ctx.NOT() != null);
    }

    @Override
    public Expr visitIn_predicate_value(SQLParser.In_predicate_valueContext ctx) {
        if (checkIfExist(ctx.in_value_list())) {
            int size = ctx.in_value_list().row_value_predicand().size();
            Expr[] exprs = new Expr[size];
            for (int i = 0; i < size; i++) {
                exprs[i] = visitRow_value_predicand(ctx.in_value_list().row_value_predicand(i));
            }
            return new ValueListExpr(exprs);
        } else {
            return new SimpleTableSubQuery(visitChildren(ctx.table_subquery()));
        }
    }

    @Override
    public Expr visitArray(SQLParser.ArrayContext ctx) {
        int size = ctx.numeric_value_expression().size();
        Expr[] exprs = new Expr[size];
        for (int i = 0; i < size; i++) {
            exprs[i] = visit(ctx.numeric_value_expression(i));
        }
        return new ValueListExpr(exprs);
    }

    @Override
    public Expr visitPattern_matching_predicate(SQLParser.Pattern_matching_predicateContext ctx) {
        Expr predicand = visitChildren(ctx.row_value_predicand());
        Expr pattern = new LiteralValue(stripQuote(ctx.Character_String_Literal().getText()), LiteralType.String);

        if (checkIfExist(ctx.pattern_matcher().negativable_matcher())) {
            boolean not = ctx.pattern_matcher().NOT() != null;
            Negativable_matcherContext matcher = ctx.pattern_matcher().negativable_matcher();
            if (checkIfExist(matcher.LIKE())) {
                return new PatternMatchPredicate(OpType.LikePredicate, not, predicand, pattern);
            } else if (checkIfExist(matcher.ILIKE())) {
                return new PatternMatchPredicate(OpType.LikePredicate, not, predicand, pattern, true);
            } else if (checkIfExist(matcher.SIMILAR())) {
                return new PatternMatchPredicate(OpType.SimilarToPredicate, not, predicand, pattern);
            } else if (checkIfExist(matcher.REGEXP()) || checkIfExist(matcher.RLIKE())) {
                return new PatternMatchPredicate(OpType.Regexp, not, predicand, pattern);
            } else {
                throw new SQLSyntaxError("Unsupported predicate: " + matcher.getText());
            }
        } else if (checkIfExist(ctx.pattern_matcher().regex_matcher())) {
            Regex_matcherContext matcher = ctx.pattern_matcher().regex_matcher();
            if (checkIfExist(matcher.Similar_To())) {
                return new PatternMatchPredicate(OpType.Regexp, false, predicand, pattern, false);
            } else if (checkIfExist(matcher.Not_Similar_To())) {
                return new PatternMatchPredicate(OpType.Regexp, true, predicand, pattern, false);
            } else if (checkIfExist(matcher.Similar_To_Case_Insensitive())) {
                return new PatternMatchPredicate(OpType.Regexp, false, predicand, pattern, true);
            } else if (checkIfExist(matcher.Not_Similar_To_Case_Insensitive())) {
                return new PatternMatchPredicate(OpType.Regexp, true, predicand, pattern, true);
            } else {
                throw new SQLSyntaxError("Unsupported predicate: " + matcher.getText());
            }
        } else {
            throw new SQLSyntaxError("Unsupported predicate: " + ctx.pattern_matcher().getText());
        }
    }

    @Override
    public IsNullPredicate visitNull_predicate(SQLParser.Null_predicateContext ctx) {
        Expr predicand = visitRow_value_predicand(ctx.row_value_predicand());
        return new IsNullPredicate(ctx.NOT() != null, predicand);
    }

    @Override
    public ExistsPredicate visitExists_predicate(SQLParser.Exists_predicateContext ctx) {
        return new ExistsPredicate(new SimpleTableSubQuery(visitTable_subquery(ctx.table_subquery())),
                ctx.NOT() != null);
    }

    @Override
    public ColumnReferenceExpr visitColumn_reference(SQLParser.Column_referenceContext ctx) {
        ColumnReferenceExpr column = new ColumnReferenceExpr(ctx.name.getText());
        if (checkIfExist(ctx.db_name)) {
            column.setQualifier(CatalogUtil.buildFQName(ctx.db_name.getText(), ctx.tb_name.getText()));
        } else if (ctx.tb_name != null) {
            column.setQualifier(ctx.tb_name.getText());
        }

        return column;
    }

    @Override
    public LiteralValue visitUnsigned_numeric_literal(@NotNull SQLParser.Unsigned_numeric_literalContext ctx) {
        if (ctx.NUMBER() != null) {
            long lValue = Long.parseLong(ctx.getText());
            if (lValue >= Integer.MIN_VALUE && lValue <= Integer.MAX_VALUE) {
                return new LiteralValue(ctx.getText(), LiteralType.Unsigned_Integer);
            } else {
                return new LiteralValue(ctx.getText(), LiteralType.Unsigned_Large_Integer);
            }
        } else {
            return new LiteralValue(ctx.getText(), LiteralType.Unsigned_Float);
        }
    }

    @Override
    public FunctionExpr visitAggregate_function(SQLParser.Aggregate_functionContext ctx) {
        if (ctx.COUNT() != null && ctx.MULTIPLY() != null) {
            return new CountRowsFunctionExpr();
        } else {
            return visitGeneral_set_function(ctx.general_set_function());
        }
    }

    @Override
    public FunctionExpr visitGeneral_set_function(SQLParser.General_set_functionContext ctx) {
        String signature = ctx.set_function_type().getText();
        boolean distinct = checkIfExist(ctx.set_qualifier()) && checkIfExist(ctx.set_qualifier().DISTINCT());
        Expr param = visitValue_expression(ctx.value_expression());

        return new GeneralSetFunctionExpr(signature, distinct, param);
    }

    @Override
    public FunctionExpr visitRoutine_invocation(SQLParser.Routine_invocationContext ctx) {
        String signature = ctx.function_name().getText();
        FunctionExpr function = new FunctionExpr(signature);
        if (ctx.sql_argument_list() != null) {
            int numArgs = ctx.sql_argument_list().value_expression().size();
            Expr[] argument_list = new Expr[numArgs];
            for (int i = 0; i < numArgs; i++) {
                argument_list[i] = visitValue_expression(ctx.sql_argument_list().value_expression().get(i));
            }

            function.setParams(argument_list);
        }
        return function;
    }

    @Override
    public NamedExpr visitDerived_column(Derived_columnContext ctx) {
        NamedExpr target = new NamedExpr(visitValue_expression(ctx.value_expression()));
        if (ctx.as_clause() != null) {
            target.setAlias(ctx.as_clause().identifier().getText());
        }
        return target;
    }

    @Override
    public NamedExpr visitQualified_asterisk(Qualified_asteriskContext ctx) {
        QualifiedAsteriskExpr target = new QualifiedAsteriskExpr();
        if (ctx.tb_name != null) {
            target.setQualifier(ctx.tb_name.getText());
        }

        return new NamedExpr(target);
    }

    @Override
    public Expr visitCharacter_string_type(SQLParser.Character_string_typeContext ctx) {
        return new LiteralValue(stripQuote(ctx.getText()), LiteralType.String);
    }

    @Override
    public Expr visitCharacter_value_expression(SQLParser.Character_value_expressionContext ctx) {
        Expr current = visitCharacter_factor(ctx.character_factor(0));

        Expr left;
        Expr right;
        for (int i = 1; i < ctx.getChildCount(); i++) {
            left = current;
            i++; // skip '||' operator
            right = visitCharacter_factor((Character_factorContext) ctx.getChild(i));

            if (left.getType() == OpType.Literal && right.getType() == OpType.Literal) {
                current = new LiteralValue(((LiteralValue) left).getValue() + ((LiteralValue) right).getValue(),
                        LiteralType.String);
            } else {
                current = new BinaryOperator(OpType.Concatenate, left, right);
            }
        }

        return current;
    }

    @Override
    public Expr visitNumeric_value_function(Numeric_value_functionContext ctx) {
        if (checkIfExist(ctx.extract_expression())) {
            return visitExtract_expression(ctx.extract_expression());
        }

        return null;
    }

    @Override
    public Expr visitExtract_expression(Extract_expressionContext ctx) {
        Expr extractTarget = new LiteralValue(ctx.extract_field_string.getText(), LiteralType.String);
        Expr extractSource;
        if (checkIfExist(ctx.extract_source().column_reference())) {
            extractSource = visitColumn_reference(ctx.extract_source().column_reference());
        } else if (checkIfExist(ctx.extract_source().datetime_literal())) {
            extractSource = visitDatetime_literal(ctx.extract_source().datetime_literal());
        } else {
            return null;
        }

        String functionName = "date_part";
        Expr[] params = new Expr[] { extractTarget, extractSource };

        return new FunctionExpr(functionName, params);
    }

    @Override
    public Expr visitTrim_function(SQLParser.Trim_functionContext ctx) {
        Expr trimSource = visitChildren(ctx.trim_operands().trim_source);
        String functionName = "trim";
        if (checkIfExist(ctx.trim_operands().FROM())) {
            if (checkIfExist(ctx.trim_operands().trim_specification())) {
                Trim_specificationContext specification = ctx.trim_operands().trim_specification();
                if (checkIfExist(specification.LEADING())) {
                    functionName = "ltrim";
                } else if (checkIfExist(specification.TRAILING())) {
                    functionName = "rtrim";
                } else {
                    functionName = "trim";
                }
            }
        }

        Expr trimCharacters = null;
        if (checkIfExist(ctx.trim_operands().trim_character)) {
            trimCharacters = visitCharacter_value_expression(ctx.trim_operands().trim_character);
        }

        Expr[] params;
        if (trimCharacters != null) {
            params = new Expr[] { trimSource, trimCharacters };
        } else {
            params = new Expr[] { trimSource };
        }

        return new FunctionExpr(functionName, params);
    }

    @Override
    public Expr visitDatabase_definition(@NotNull SQLParser.Database_definitionContext ctx) {
        return new CreateDatabase(ctx.identifier().getText(), null, checkIfExist(ctx.if_not_exists()));
    }

    @Override
    public Expr visitDrop_database_statement(@NotNull SQLParser.Drop_database_statementContext ctx) {
        return new DropDatabase(ctx.identifier().getText(), checkIfExist(ctx.if_exists()));
    }

    @Override
    public Expr visitCreate_table_statement(SQLParser.Create_table_statementContext ctx) {
        String tableName = ctx.table_name().getText();
        CreateTable createTable = new CreateTable(tableName, checkIfExist(ctx.if_not_exists()));

        if (checkIfExist(ctx.EXTERNAL())) {
            createTable.setExternal();

            ColumnDefinition[] elements = getDefinitions(ctx.table_elements());
            String fileType = ctx.file_type.getText();
            String path = stripQuote(ctx.path.getText());

            createTable.setTableElements(elements);
            createTable.setStorageType(fileType);
            createTable.setLocation(path);
        } else {
            if (checkIfExist(ctx.table_elements())) {
                ColumnDefinition[] elements = getDefinitions(ctx.table_elements());
                createTable.setTableElements(elements);
            }

            if (checkIfExist(ctx.USING())) {
                String fileType = ctx.file_type.getText();
                createTable.setStorageType(fileType);
            }

            if (checkIfExist(ctx.query_expression())) {
                Expr subquery = visitQuery_expression(ctx.query_expression());
                createTable.setSubQuery(subquery);
            }
        }

        if (checkIfExist(ctx.param_clause())) {
            Map<String, String> params = escapeTableMeta(getParams(ctx.param_clause()));
            createTable.setParams(params);
        }

        if (checkIfExist(ctx.table_partitioning_clauses())) {
            PartitionMethodDescExpr partitionMethodDesc = parseTablePartitioningClause(
                    ctx.table_partitioning_clauses());
            createTable.setPartitionMethod(partitionMethodDesc);
        }
        return createTable;
    }

    private ColumnDefinition[] getDefinitions(SQLParser.Table_elementsContext ctx) {
        int size = ctx.field_element().size();
        ColumnDefinition[] elements = new ColumnDefinition[size];
        for (int i = 0; i < size; i++) {
            String name = ctx.field_element(i).name.getText();
            DataTypeExpr typeDef = visitData_type(ctx.field_element(i).field_type().data_type());
            elements[i] = new ColumnDefinition(name, typeDef);
        }

        return elements;
    }

    public PartitionMethodDescExpr parseTablePartitioningClause(SQLParser.Table_partitioning_clausesContext ctx) {

        if (checkIfExist(ctx.range_partitions())) { // For Range Partition
            Range_partitionsContext rangePartitionsContext = ctx.range_partitions();
            List<Range_value_clauseContext> rangeValueClause = rangePartitionsContext.range_value_clause_list()
                    .range_value_clause();

            List<RangePartitionSpecifier> specifiers = Lists.newArrayList();

            for (Range_value_clauseContext rangeValue : rangeValueClause) {
                if (checkIfExist(rangeValue.MAXVALUE())) { // LESS THAN (MAXVALUE)
                    specifiers.add(new RangePartitionSpecifier(rangeValue.partition_name().getText()));
                } else { // LESS THAN (expr)
                    specifiers.add(new RangePartitionSpecifier(rangeValue.partition_name().getText(),
                            visitValue_expression(rangeValue.value_expression())));
                }
            }
            return new CreateTable.RangePartition(
                    getColumnReferences(ctx.range_partitions().column_reference_list()), specifiers);

        } else if (checkIfExist(ctx.hash_partitions())) { // For Hash Partition
            Hash_partitionsContext hashPartitions = ctx.hash_partitions();

            if (checkIfExist(hashPartitions.hash_partitions_by_quantity())) { // PARTITIONS (num)
                return new HashPartition(getColumnReferences(hashPartitions.column_reference_list()),
                        visitNumeric_value_expression(hashPartitions.hash_partitions_by_quantity().quantity));

            } else { // ( PARTITION part_name , ...)
                List<PartitionSpecifier> specifiers = Lists.newArrayList();
                for (Individual_hash_partitionContext partition : hashPartitions.individual_hash_partitions()
                        .individual_hash_partition()) {
                    specifiers.add(new CreateTable.PartitionSpecifier(partition.partition_name().getText()));
                }
                return new HashPartition(getColumnReferences(hashPartitions.column_reference_list()), specifiers);
            }

        } else if (checkIfExist(ctx.list_partitions())) { // For List Partition
            List_partitionsContext listPartitions = ctx.list_partitions();
            List<List_value_partitionContext> partitions = listPartitions.list_value_clause_list()
                    .list_value_partition();
            List<ListPartitionSpecifier> specifiers = Lists.newArrayList();

            for (List_value_partitionContext listValuePartition : partitions) {
                int size = listValuePartition.in_value_list().row_value_predicand().size();
                Expr[] exprs = new Expr[size];
                for (int i = 0; i < size; i++) {
                    exprs[i] = visitRow_value_predicand(listValuePartition.in_value_list().row_value_predicand(i));
                }
                specifiers.add(new ListPartitionSpecifier(listValuePartition.partition_name().getText(),
                        new ValueListExpr(exprs)));
            }
            return new ListPartition(getColumnReferences(ctx.list_partitions().column_reference_list()),
                    specifiers);

        } else if (checkIfExist(ctx.column_partitions())) { // For Column Partition (Hive Style)
            return new CreateTable.ColumnPartition(getDefinitions(ctx.column_partitions().table_elements()), true);
        } else {
            throw new SQLSyntaxError("Invalid Partition Type: " + ctx.toStringTree());
        }
    }

    @Override
    public DataTypeExpr visitData_type(SQLParser.Data_typeContext ctx) {
        SQLParser.Predefined_typeContext predefined_type = ctx.predefined_type();

        DataTypeExpr typeDefinition = null;
        if (predefined_type.character_string_type() != null) {
            SQLParser.Character_string_typeContext character_string_type = predefined_type.character_string_type();

            if ((character_string_type.CHARACTER() != null || character_string_type.CHAR() != null)
                    && character_string_type.VARYING() == null) {

                typeDefinition = new DataTypeExpr(Type.CHAR.name());

                if (character_string_type.type_length() != null) {
                    typeDefinition.setLengthOrPrecision(
                            Integer.parseInt(character_string_type.type_length().NUMBER().getText()));
                }

            } else if (character_string_type.VARCHAR() != null || character_string_type.VARYING() != null) {

                typeDefinition = new DataTypeExpr(Type.VARCHAR.name());

                if (character_string_type.type_length() != null) {
                    typeDefinition.setLengthOrPrecision(
                            Integer.parseInt(character_string_type.type_length().NUMBER().getText()));
                }

            } else if (character_string_type.TEXT() != null) {
                typeDefinition = new DataTypeExpr(Type.TEXT.name());
            }

        } else if (predefined_type.national_character_string_type() != null) {
            SQLParser.National_character_string_typeContext nchar_type = predefined_type
                    .national_character_string_type();
            if ((nchar_type.CHAR() != null || nchar_type.CHARACTER() != null || nchar_type.NCHAR() != null)
                    && nchar_type.VARYING() == null) {
                typeDefinition = new DataTypeExpr(Type.NCHAR.name());
            } else if (nchar_type.NVARCHAR() != null || nchar_type.VARYING() != null) {
                typeDefinition = new DataTypeExpr(Type.NVARCHAR.name());
            }

            if (nchar_type.type_length() != null) {
                typeDefinition.setLengthOrPrecision(Integer.parseInt(nchar_type.type_length().NUMBER().getText()));
            }

        } else if (predefined_type.binary_large_object_string_type() != null) {
            SQLParser.Binary_large_object_string_typeContext blob_type = predefined_type
                    .binary_large_object_string_type();
            typeDefinition = new DataTypeExpr(Type.BLOB.name());
            if (blob_type.type_length() != null) {
                typeDefinition.setLengthOrPrecision(Integer.parseInt(blob_type.type_length().NUMBER().getText()));
            }
        } else if (predefined_type.numeric_type() != null) {
            // exact number
            if (predefined_type.numeric_type().exact_numeric_type() != null) {
                SQLParser.Exact_numeric_typeContext exactType = predefined_type.numeric_type().exact_numeric_type();
                if (exactType.TINYINT() != null || exactType.INT1() != null) {
                    typeDefinition = new DataTypeExpr(Type.INT1.name());
                } else if (exactType.INT2() != null || exactType.SMALLINT() != null) {
                    typeDefinition = new DataTypeExpr(Type.INT2.name());
                } else if (exactType.INT4() != null || exactType.INTEGER() != null || exactType.INT() != null) {
                    typeDefinition = new DataTypeExpr(Type.INT4.name());
                } else if (exactType.INT8() != null || exactType.BIGINT() != null) {
                    typeDefinition = new DataTypeExpr(Type.INT8.name());
                } else if (exactType.NUMERIC() != null) {
                    typeDefinition = new DataTypeExpr(Type.NUMERIC.name());
                } else if (exactType.DECIMAL() != null || exactType.DEC() != null) {
                    typeDefinition = new DataTypeExpr(Type.NUMERIC.name());
                }

                if (typeDefinition.getTypeName().equals(Type.NUMERIC.name())) {
                    if (exactType.precision_param() != null) {
                        if (exactType.precision_param().scale != null) {
                            typeDefinition.setScale(Integer.parseInt(exactType.precision_param().scale.getText()));
                        }
                        typeDefinition.setLengthOrPrecision(
                                Integer.parseInt(exactType.precision_param().precision.getText()));
                    }
                }
            } else { // approximate number
                SQLParser.Approximate_numeric_typeContext approximateType = predefined_type.numeric_type()
                        .approximate_numeric_type();
                if (approximateType.FLOAT() != null || approximateType.FLOAT4() != null
                        || approximateType.REAL() != null) {
                    typeDefinition = new DataTypeExpr(Type.FLOAT4.name());
                } else if (approximateType.FLOAT8() != null || approximateType.DOUBLE() != null) {
                    typeDefinition = new DataTypeExpr(Type.FLOAT8.name());
                }
            }
        } else if (predefined_type.boolean_type() != null) {
            typeDefinition = new DataTypeExpr(Type.BOOLEAN.name());
        } else if (predefined_type.datetime_type() != null) {
            SQLParser.Datetime_typeContext dateTimeType = predefined_type.datetime_type();
            if (dateTimeType.DATE() != null) {
                typeDefinition = new DataTypeExpr(Type.DATE.name());
            } else if (dateTimeType.TIME(0) != null && dateTimeType.ZONE() == null) {
                typeDefinition = new DataTypeExpr(Type.TIME.name());
            } else if ((dateTimeType.TIME(0) != null && dateTimeType.ZONE() != null)
                    || dateTimeType.TIMETZ() != null) {
                typeDefinition = new DataTypeExpr(Type.TIMEZ.name());
            } else if (dateTimeType.TIMESTAMP() != null && dateTimeType.ZONE() == null) {
                typeDefinition = new DataTypeExpr(Type.TIMESTAMP.name());
            } else if ((dateTimeType.TIMESTAMP() != null && dateTimeType.ZONE() != null)
                    || dateTimeType.TIMESTAMPTZ() != null) {
                typeDefinition = new DataTypeExpr(Type.TIMESTAMPZ.name());
            }
        } else if (predefined_type.bit_type() != null) {
            SQLParser.Bit_typeContext bitType = predefined_type.bit_type();
            if (bitType.VARBIT() != null || bitType.VARYING() != null) {
                typeDefinition = new DataTypeExpr(Type.VARBIT.name());
            } else {
                typeDefinition = new DataTypeExpr(Type.BIT.name());
            }
            if (bitType.type_length() != null) {
                typeDefinition.setLengthOrPrecision(Integer.parseInt(bitType.type_length().NUMBER().getText()));
            }
        } else if (predefined_type.binary_type() != null) {
            SQLParser.Binary_typeContext binaryType = predefined_type.binary_type();
            if (binaryType.VARBINARY() != null || binaryType.VARYING() != null) {
                typeDefinition = new DataTypeExpr(Type.VARBINARY.name());
            } else {
                typeDefinition = new DataTypeExpr(Type.BINARY.name());
            }

            if (binaryType.type_length() != null) {
                typeDefinition.setLengthOrPrecision(Integer.parseInt(binaryType.type_length().NUMBER().getText()));
            }
        } else if (predefined_type.network_type() != null) {
            typeDefinition = new DataTypeExpr(Type.INET4.name());
        }

        return typeDefinition;
    }

    @Override
    public Expr visitInsert_statement(SQLParser.Insert_statementContext ctx) {
        Insert insertExpr = new Insert();

        if (ctx.OVERWRITE() != null) {
            insertExpr.setOverwrite();
        }

        if (ctx.table_name() != null) {
            insertExpr.setTableName(ctx.table_name().getText());

            if (ctx.column_name_list() != null) {
                String[] targetColumns = new String[ctx.column_name_list().identifier().size()];
                for (int i = 0; i < targetColumns.length; i++) {
                    targetColumns[i] = ctx.column_name_list().identifier().get(i).getText();
                }

                insertExpr.setTargetColumns(targetColumns);
            }
        }

        if (ctx.LOCATION() != null) {
            insertExpr.setLocation(stripQuote(ctx.path.getText()));

            if (ctx.USING() != null) {
                insertExpr.setStorageType(ctx.file_type.getText());

                if (ctx.param_clause() != null) {
                    insertExpr.setParams(escapeTableMeta(getParams(ctx.param_clause())));
                }
            }
        }

        insertExpr.setSubQuery(visitQuery_expression(ctx.query_expression()));

        Preconditions.checkState(insertExpr.hasTableName() || insertExpr.hasLocation(),
                "Either a table name or a location should be given.");
        Preconditions.checkState(insertExpr.hasTableName() ^ insertExpr.hasLocation(),
                "A table name and a location cannot coexist.");
        return insertExpr;
    }

    @Override
    public Expr visitDrop_table_statement(SQLParser.Drop_table_statementContext ctx) {
        return new DropTable(ctx.table_name().getText(), checkIfExist(ctx.if_exists()), checkIfExist(ctx.PURGE()));
    }

    private Map<String, String> getParams(SQLParser.Param_clauseContext ctx) {
        Map<String, String> params = new HashMap<String, String>();
        for (int i = 0; i < ctx.param().size(); i++) {
            params.put(stripQuote(ctx.param(i).key.getText()), stripQuote(ctx.param(i).value.getText()));
        }

        return params;
    }

    public Map<String, String> escapeTableMeta(Map<String, String> map) {
        Map<String, String> params = new HashMap<String, String>();
        for (Map.Entry<String, String> entry : map.entrySet()) {
            if (entry.getKey().equals(StorageConstants.CSVFILE_DELIMITER)) {
                params.put(entry.getKey(), escapeDelimiter(entry.getValue()));
            } else {
                params.put(entry.getKey(), entry.getValue());
            }
        }
        return params;
    }

    public static String escapeDelimiter(String value) {
        try {
            String delimiter = StringEscapeUtils.unescapeJava(value);
            delimiter = new String(new byte[] { Byte.valueOf(delimiter).byteValue() });
            return StringEscapeUtils.escapeJava(delimiter);
        } catch (NumberFormatException e) {
        }
        return value;
    }

    private static String stripQuote(String str) {
        return str.substring(1, str.length() - 1);
    }

    @Override
    public Expr visitCast_specification(SQLParser.Cast_specificationContext ctx) {
        Expr operand = visitChildren(ctx.cast_operand());
        DataTypeExpr castTarget = visitData_type(ctx.cast_target().data_type());
        return new CastExpr(operand, castTarget);
    }

    @Override
    public Expr visitUnsigned_value_specification(@NotNull SQLParser.Unsigned_value_specificationContext ctx) {
        return visitChildren(ctx);
    }

    @Override
    public Expr visitUnsigned_literal(@NotNull SQLParser.Unsigned_literalContext ctx) {
        if (checkIfExist(ctx.unsigned_numeric_literal())) {
            return visitUnsigned_numeric_literal(ctx.unsigned_numeric_literal());
        } else {
            return visitGeneral_literal(ctx.general_literal());
        }
    }

    @Override
    public Expr visitGeneral_literal(SQLParser.General_literalContext ctx) {
        if (checkIfExist(ctx.Character_String_Literal())) {
            return new LiteralValue(stripQuote(ctx.Character_String_Literal().getText()), LiteralType.String);
        } else if (checkIfExist(ctx.datetime_literal())) {
            return visitDatetime_literal(ctx.datetime_literal());
        } else {
            return new BooleanLiteral(checkIfExist(ctx.boolean_literal().TRUE()));
        }
    }

    @Override
    public Expr visitDatetime_literal(@NotNull SQLParser.Datetime_literalContext ctx) {
        if (checkIfExist(ctx.time_literal())) {
            return visitTime_literal(ctx.time_literal());
        } else if (checkIfExist(ctx.date_literal())) {
            return visitDate_literal(ctx.date_literal());
        } else {
            return visitTimestamp_literal(ctx.timestamp_literal());
        }
    }

    @Override
    public Expr visitTime_literal(SQLParser.Time_literalContext ctx) {
        String timePart = stripQuote(ctx.time_string.getText());
        return new TimeLiteral(parseTime(timePart));
    }

    @Override
    public Expr visitDate_literal(SQLParser.Date_literalContext ctx) {
        String datePart = stripQuote(ctx.date_string.getText());
        return new DateLiteral(parseDate(datePart));
    }

    @Override
    public Expr visitTimestamp_literal(SQLParser.Timestamp_literalContext ctx) {
        String timestampStr = stripQuote(ctx.timestamp_string.getText());
        String[] parts = timestampStr.split(" ");
        String datePart = parts[0];
        String timePart = parts[1];
        return new TimestampLiteral(parseDate(datePart), parseTime(timePart));
    }

    private DateValue parseDate(String datePart) {
        // e.g., 1980-04-01
        String[] parts = datePart.split("-");
        return new DateValue(parts[0], parts[1], parts[2]);
    }

    private TimeValue parseTime(String timePart) {
        // e.g., 12:01:50.399
        String[] parts = timePart.split(":");

        TimeValue time;
        boolean hasFractionOfSeconds = parts[2].indexOf('.') > 0;
        if (hasFractionOfSeconds) {
            String[] secondsParts = parts[2].split("\\.");
            time = new TimeValue(parts[0], parts[1], secondsParts[0]);
            if (secondsParts.length == 2) {
                time.setSecondsFraction(secondsParts[1]);
            }
        } else {
            time = new TimeValue(parts[0], parts[1], parts[2]);
        }
        return time;
    }

    @Override
    public Expr visitAlter_table_statement(SQLParser.Alter_table_statementContext ctx) {

        final List<Table_nameContext> tables = ctx.table_name();

        final AlterTable alterTable = new AlterTable(tables.get(0).getText());

        if (tables.size() == 2) {
            alterTable.setNewTableName(tables.get(1).getText());
        }

        if (checkIfExist(ctx.column_name()) && ctx.column_name().size() == 2) {
            final List<Column_nameContext> columns = ctx.column_name();
            alterTable.setColumnName(columns.get(0).getText());
            alterTable.setNewColumnName(columns.get(1).getText());
        }

        Field_elementContext field_elementContext = ctx.field_element();
        if (checkIfExist(field_elementContext)) {
            final String name = field_elementContext.name.getText();
            final DataTypeExpr typeDef = visitData_type(field_elementContext.field_type().data_type());
            final ColumnDefinition columnDefinition = new ColumnDefinition(name, typeDef);
            alterTable.setAddNewColumn(columnDefinition);
        }

        alterTable.setAlterTableOpType(determineAlterTableType(ctx));

        return alterTable;
    }

    private AlterTableOpType determineAlterTableType(SQLParser.Alter_table_statementContext ctx) {

        final int RENAME_MASK = 00000001;
        final int COLUMN_MASK = 00000010;
        final int TO_MASK = 00000100;
        final int ADD_MASK = 00001000;

        int val = 00000000;

        for (int idx = 1; idx < ctx.getChildCount(); idx++) {

            if (ctx.getChild(idx) instanceof TerminalNode) {
                if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == RENAME) {
                    val = val | RENAME_MASK;
                }
                if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == COLUMN) {
                    val = val | COLUMN_MASK;
                }
                if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == TO) {
                    val = val | TO_MASK;
                }
                if (((TerminalNode) ctx.getChild(idx)).getSymbol().getType() == ADD) {
                    val = val | ADD_MASK;
                }
            }
        }
        return evaluateAlterTableOperationTye(val);
    }

    private AlterTableOpType evaluateAlterTableOperationTye(final int value) {

        switch (value) {
        case 65:
            return AlterTableOpType.RENAME_TABLE;
        case 73:
            return AlterTableOpType.RENAME_COLUMN;
        case 520:
            return AlterTableOpType.ADD_COLUMN;
        default:
            return null;
        }
    }
}