/*
    * 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 org.apache.shardingsphere.sql.parser.sqlserver.visitor.statement.type;
  
  import org.antlr.v4.runtime.ParserRuleContext;
  import org.antlr.v4.runtime.misc.Interval;
  import org.apache.shardingsphere.sql.parser.api.ASTNode;
  import org.apache.shardingsphere.sql.parser.api.visitor.statement.type.DDLStatementVisitor;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AddColumnSpecificationContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterCheckConstraintContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterColumnAddOptionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterDatabaseContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterDefinitionClauseContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterFunctionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterIndexContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterProcedureContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterSchemaContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterSequenceContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterServiceContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterTableContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterTableDropConstraintContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterTriggerContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.AlterViewContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ColumnConstraintContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ColumnDefinitionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ColumnDefinitionOptionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ColumnNameContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ColumnNameWithSortContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateDatabaseContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateFunctionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateIndexContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateProcedureContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateSchemaContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateSequenceContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateServiceContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateTableClauseContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateTableContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateTableDefinitionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateTableDefinitionsContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateTriggerContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.CreateViewContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropColumnSpecificationContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropConstraintNameContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropDatabaseContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropFunctionContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropIndexContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropProcedureContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropSchemaContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropSequenceContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropServiceContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropTableContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropTriggerContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.DropViewContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ModifyColumnSpecificationContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.TableConstraintContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.TruncateTableContext;
  import org.apache.shardingsphere.sql.parser.autogen.SQLServerStatementParser.ViewNameContext;
  import org.apache.shardingsphere.sql.parser.sqlserver.visitor.statement.SQLServerStatementVisitor;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.AlterDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.CreateDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.column.ColumnDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.column.alter.AddColumnDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.column.alter.DropColumnDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.column.alter.ModifyColumnDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.constraint.ConstraintDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.constraint.ConstraintSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.constraint.alter.AddConstraintDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.constraint.alter.DropConstraintDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.constraint.alter.ModifyConstraintDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.index.IndexSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.dml.column.ColumnSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.generic.DataTypeSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.generic.table.SimpleTableSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.TruncateStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.database.AlterDatabaseStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.database.CreateDatabaseStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.database.DropDatabaseStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.function.AlterFunctionStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.function.CreateFunctionStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.function.DropFunctionStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.index.AlterIndexStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.index.CreateIndexStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.index.DropIndexStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.procedure.AlterProcedureStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.procedure.CreateProcedureStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.procedure.DropProcedureStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.schema.AlterSchemaStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.schema.CreateSchemaStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.schema.DropSchemaStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.sequence.AlterSequenceStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.sequence.CreateSequenceStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.sequence.DropSequenceStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.table.AlterTableStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.table.CreateTableStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.table.DropTableStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.trigger.AlterTriggerStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.trigger.CreateTriggerStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.trigger.DropTriggerStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.view.AlterViewStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.view.CreateViewStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.view.DropViewStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dml.SelectStatement;
 import org.apache.shardingsphere.sql.parser.statement.core.value.collection.CollectionValue;
 import org.apache.shardingsphere.sql.parser.statement.sqlserver.ddl.service.SQLServerAlterServiceStatement;
 import org.apache.shardingsphere.sql.parser.statement.sqlserver.ddl.service.SQLServerCreateServiceStatement;
 import org.apache.shardingsphere.sql.parser.statement.sqlserver.ddl.service.SQLServerDropServiceStatement;
 
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedList;
 
 /**
  * DDL statement visitor for SQLServer.
  */
 public final class SQLServerDDLStatementVisitor extends SQLServerStatementVisitor implements DDLStatementVisitor {
     
     @Override
     public ASTNode visitCreateTable(final CreateTableContext ctx) {
         return null == ctx.createTableClause() ? visit(ctx.createTableAsSelectClause()) : visit(ctx.createTableClause());
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public ASTNode visitCreateTableClause(final CreateTableClauseContext ctx) {
         CreateTableStatement result = new CreateTableStatement();
         result.setTable((SimpleTableSegment) visit(ctx.tableName()));
         CollectionValue<CreateDefinitionSegment> createDefinitions = (CollectionValue<CreateDefinitionSegment>) generateCreateDefinitionSegment(ctx.createDefinitionClause().createTableDefinitions());
         for (CreateDefinitionSegment each : createDefinitions.getValue()) {
             if (each instanceof ColumnDefinitionSegment) {
                 result.getColumnDefinitions().add((ColumnDefinitionSegment) each);
             } else if (each instanceof ConstraintDefinitionSegment) {
                 result.getConstraintDefinitions().add((ConstraintDefinitionSegment) each);
             }
         }
         return result;
     }
     
     private ASTNode generateCreateDefinitionSegment(final CreateTableDefinitionsContext ctx) {
         CollectionValue<CreateDefinitionSegment> result = new CollectionValue<>();
         for (CreateTableDefinitionContext each : ctx.createTableDefinition()) {
             if (null != each.columnDefinition()) {
                 result.getValue().add((ColumnDefinitionSegment) visit(each.columnDefinition()));
             }
             if (null != each.tableConstraint()) {
                 result.getValue().add((ConstraintDefinitionSegment) visit(each.tableConstraint()));
             }
         }
         return result;
     }
     
     @Override
     public ASTNode visitColumnDefinition(final ColumnDefinitionContext ctx) {
         ColumnSegment column = (ColumnSegment) visit(ctx.columnName());
         DataTypeSegment dataType = (DataTypeSegment) visit(ctx.dataType());
         boolean isPrimaryKey = isPrimaryKey(ctx);
         // TODO parse not null
         ColumnDefinitionSegment result = new ColumnDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), column, dataType, isPrimaryKey, false, getText(ctx));
         for (ColumnDefinitionOptionContext each : ctx.columnDefinitionOption()) {
             for (ColumnConstraintContext columnConstraint : each.columnConstraint()) {
                 if (null != columnConstraint.columnForeignKeyConstraint()) {
                     result.getReferencedTables().add((SimpleTableSegment) visit(columnConstraint.columnForeignKeyConstraint().tableName()));
                 }
             }
         }
         for (ColumnConstraintContext each : ctx.columnConstraints().columnConstraint()) {
             if (null != each.columnForeignKeyConstraint()) {
                 result.getReferencedTables().add((SimpleTableSegment) visit(each.columnForeignKeyConstraint().tableName()));
             }
         }
         return result;
     }
     
     private String getText(final ParserRuleContext ctx) {
         return ctx.start.getInputStream().getText(new Interval(ctx.start.getStartIndex(), ctx.stop.getStopIndex()));
     }
     
     private boolean isPrimaryKey(final ColumnDefinitionContext ctx) {
         for (ColumnDefinitionOptionContext each : ctx.columnDefinitionOption()) {
             for (ColumnConstraintContext columnConstraint : each.columnConstraint()) {
                 if (null != columnConstraint.primaryKeyConstraint() && null != columnConstraint.primaryKeyConstraint().primaryKey()) {
                     return true;
                 }
             }
         }
         for (ColumnConstraintContext each : ctx.columnConstraints().columnConstraint()) {
             if (null != each.primaryKeyConstraint() && null != each.primaryKeyConstraint().primaryKey()) {
                 return true;
             }
         }
         return false;
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public ASTNode visitTableConstraint(final TableConstraintContext ctx) {
         ConstraintDefinitionSegment result = new ConstraintDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex());
         if (null != ctx.constraintName()) {
             result.setConstraintName((ConstraintSegment) visit(ctx.constraintName()));
         }
         if (null != ctx.tablePrimaryConstraint() && null != ctx.tablePrimaryConstraint().primaryKeyUnique().primaryKey()) {
             if (null != ctx.tablePrimaryConstraint().diskTablePrimaryConstraintOption()) {
                 result.getPrimaryKeyColumns().addAll(((CollectionValue<ColumnSegment>) visit(ctx.tablePrimaryConstraint().diskTablePrimaryConstraintOption().columnNames())).getValue());
             }
             if (null != ctx.tablePrimaryConstraint().memoryTablePrimaryConstraintOption()) {
                 result.getPrimaryKeyColumns().addAll(((CollectionValue<ColumnSegment>) visit(ctx.tablePrimaryConstraint().memoryTablePrimaryConstraintOption().columnNames())).getValue());
             }
         }
         if (null != ctx.tableForeignKeyConstraint()) {
             result.setReferencedTable((SimpleTableSegment) visit(ctx.tableForeignKeyConstraint().tableName()));
         }
         return result;
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public ASTNode visitAlterTable(final AlterTableContext ctx) {
         AlterTableStatement result = new AlterTableStatement();
         result.setTable((SimpleTableSegment) visit(ctx.tableName()));
         for (AlterDefinitionClauseContext alterDefinitionClauseContext : ctx.alterDefinitionClause()) {
             for (AlterDefinitionSegment each : ((CollectionValue<AlterDefinitionSegment>) visit(alterDefinitionClauseContext)).getValue()) {
                 if (each instanceof AddColumnDefinitionSegment) {
                     result.getAddColumnDefinitions().add((AddColumnDefinitionSegment) each);
                 } else if (each instanceof ModifyColumnDefinitionSegment) {
                     result.getModifyColumnDefinitions().add((ModifyColumnDefinitionSegment) each);
                 } else if (each instanceof DropColumnDefinitionSegment) {
                     result.getDropColumnDefinitions().add((DropColumnDefinitionSegment) each);
                 } else if (each instanceof AddConstraintDefinitionSegment) {
                     result.getAddConstraintDefinitions().add((AddConstraintDefinitionSegment) each);
                 } else if (each instanceof ModifyConstraintDefinitionSegment) {
                     result.getModifyConstraintDefinitions().add((ModifyConstraintDefinitionSegment) each);
                 } else if (each instanceof DropConstraintDefinitionSegment) {
                     result.getDropConstraintDefinitions().add((DropConstraintDefinitionSegment) each);
                 }
             }
         }
         return result;
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public ASTNode visitAlterDefinitionClause(final AlterDefinitionClauseContext ctx) {
         CollectionValue<AlterDefinitionSegment> result = new CollectionValue<>();
         if (null != ctx.addColumnSpecification()) {
             result.getValue().addAll(((CollectionValue<AddColumnDefinitionSegment>) visit(ctx.addColumnSpecification())).getValue());
         }
         if (null != ctx.modifyColumnSpecification()) {
             result.getValue().add((ModifyColumnDefinitionSegment) visit(ctx.modifyColumnSpecification()));
         }
         if (null != ctx.alterDrop() && null != ctx.alterDrop().dropColumnSpecification()) {
             result.getValue().add((DropColumnDefinitionSegment) visit(ctx.alterDrop().dropColumnSpecification()));
         }
         if (null != ctx.alterDrop() && null != ctx.alterDrop().alterTableDropConstraint()) {
             result.combine((CollectionValue<AlterDefinitionSegment>) visit(ctx.alterDrop().alterTableDropConstraint()));
         }
         if (null != ctx.alterCheckConstraint()) {
             result.getValue().add((AlterDefinitionSegment) visit(ctx.alterCheckConstraint()));
         }
         return result;
     }
     
     @Override
     public ASTNode visitAddColumnSpecification(final AddColumnSpecificationContext ctx) {
         CollectionValue<AddColumnDefinitionSegment> result = new CollectionValue<>();
         if (null != ctx.alterColumnAddOptions()) {
             for (AlterColumnAddOptionContext each : ctx.alterColumnAddOptions().alterColumnAddOption()) {
                 if (null != each.columnDefinition()) {
                     AddColumnDefinitionSegment addColumnDefinition = new AddColumnDefinitionSegment(
                             each.columnDefinition().getStart().getStartIndex(), each.columnDefinition().getStop().getStopIndex(),
                             Collections.singletonList((ColumnDefinitionSegment) visit(each.columnDefinition())));
                     result.getValue().add(addColumnDefinition);
                 }
             }
         }
         return result;
     }
     
     @Override
     public ASTNode visitModifyColumnSpecification(final ModifyColumnSpecificationContext ctx) {
         // TODO visit pk and table ref
         ColumnSegment column = (ColumnSegment) visit(ctx.alterColumnOperation().columnName());
         DataTypeSegment dataType = (DataTypeSegment) visit(ctx.dataType());
         ColumnDefinitionSegment columnDefinition = new ColumnDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), column, dataType, false, false, getText(ctx));
         return new ModifyColumnDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), columnDefinition);
     }
     
     @Override
     public ASTNode visitDropColumnSpecification(final DropColumnSpecificationContext ctx) {
         Collection<ColumnSegment> columns = new LinkedList<>();
         for (ColumnNameContext each : ctx.columnName()) {
             columns.add((ColumnSegment) visit(each));
         }
         return new DropColumnDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), columns);
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public ASTNode visitDropTable(final DropTableContext ctx) {
         DropTableStatement result = new DropTableStatement();
         result.setContainsCascade(null != ctx.ifExists());
         result.getTables().addAll(((CollectionValue<SimpleTableSegment>) visit(ctx.tableNames())).getValue());
         return result;
     }
     
     @Override
     public ASTNode visitTruncateTable(final TruncateTableContext ctx) {
         return new TruncateStatement(Collections.singleton((SimpleTableSegment) visit(ctx.tableName())));
     }
     
     @SuppressWarnings({"rawtypes", "unchecked"})
     @Override
     public ASTNode visitCreateIndex(final CreateIndexContext ctx) {
         CreateIndexStatement result = new CreateIndexStatement();
         result.setTable((SimpleTableSegment) visit(ctx.tableName()));
         result.setIndex((IndexSegment) visit(ctx.indexName()));
         result.getColumns().addAll(((CollectionValue) visit(ctx.columnNamesWithSort())).getValue());
         return result;
     }
     
     @Override
     public ASTNode visitColumnNameWithSort(final ColumnNameWithSortContext ctx) {
         return visit(ctx.columnName());
     }
     
     @Override
     public ASTNode visitAlterIndex(final AlterIndexContext ctx) {
         AlterIndexStatement result = new AlterIndexStatement();
         if (null != ctx.indexName()) {
             result.setIndex((IndexSegment) visit(ctx.indexName()));
         }
         result.setSimpleTable((SimpleTableSegment) visit(ctx.tableName()));
         return result;
     }
     
     @Override
     public ASTNode visitDropIndex(final DropIndexContext ctx) {
         DropIndexStatement result = new DropIndexStatement();
         result.setIfExists(null != ctx.ifExists());
         result.getIndexes().add((IndexSegment) visit(ctx.indexName()));
         result.setSimpleTable((SimpleTableSegment) visit(ctx.tableName()));
         return result;
     }
     
     @Override
     public ASTNode visitAlterCheckConstraint(final AlterCheckConstraintContext ctx) {
         return new ModifyConstraintDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), (ConstraintSegment) visit(ctx.constraintName()));
     }
     
     @Override
     public ASTNode visitAlterTableDropConstraint(final AlterTableDropConstraintContext ctx) {
         CollectionValue<DropConstraintDefinitionSegment> result = new CollectionValue<>();
         for (DropConstraintNameContext each : ctx.dropConstraintName()) {
             result.getValue().add(new DropConstraintDefinitionSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), (ConstraintSegment) visit(each.constraintName())));
         }
         return result;
     }
     
     @Override
     public ASTNode visitCreateDatabase(final CreateDatabaseContext ctx) {
         return new CreateDatabaseStatement(ctx.databaseName().getText(), false);
     }
     
     @Override
     public ASTNode visitCreateFunction(final CreateFunctionContext ctx) {
         return new CreateFunctionStatement();
     }
     
     @Override
     public ASTNode visitCreateProcedure(final CreateProcedureContext ctx) {
         return new CreateProcedureStatement();
     }
     
     @Override
     public ASTNode visitCreateView(final CreateViewContext ctx) {
         CreateViewStatement result = new CreateViewStatement();
         result.setReplaceView(null != ctx.ALTER());
         result.setView((SimpleTableSegment) visit(ctx.viewName()));
         result.setViewDefinition(getOriginalText(ctx.createOrAlterViewClause().select()));
         result.setSelect((SelectStatement) visit(ctx.createOrAlterViewClause().select()));
         return result;
     }
     
     @Override
     public ASTNode visitCreateTrigger(final CreateTriggerContext ctx) {
         return new CreateTriggerStatement();
     }
     
     @Override
     public ASTNode visitCreateSequence(final CreateSequenceContext ctx) {
         return new CreateSequenceStatement(ctx.sequenceName().name().getText());
     }
     
     @Override
     public ASTNode visitCreateSchema(final CreateSchemaContext ctx) {
         return new CreateSchemaStatement();
     }
     
     @Override
     public ASTNode visitCreateService(final CreateServiceContext ctx) {
         return new SQLServerCreateServiceStatement();
     }
     
     @Override
     public ASTNode visitAlterSchema(final AlterSchemaContext ctx) {
         return new AlterSchemaStatement();
     }
     
     @Override
     public ASTNode visitAlterService(final AlterServiceContext ctx) {
         return new SQLServerAlterServiceStatement();
     }
     
     @Override
     public ASTNode visitDropSchema(final DropSchemaContext ctx) {
         return new DropSchemaStatement();
     }
     
     @Override
     public ASTNode visitDropService(final DropServiceContext ctx) {
         return new SQLServerDropServiceStatement();
     }
     
     @Override
     public ASTNode visitAlterTrigger(final AlterTriggerContext ctx) {
         return new AlterTriggerStatement();
     }
     
     @Override
     public ASTNode visitAlterSequence(final AlterSequenceContext ctx) {
         return new AlterSequenceStatement(null);
     }
     
     @Override
     public ASTNode visitAlterProcedure(final AlterProcedureContext ctx) {
         return new AlterProcedureStatement();
     }
     
     @Override
     public ASTNode visitAlterFunction(final AlterFunctionContext ctx) {
         return new AlterFunctionStatement();
     }
     
     @Override
     public ASTNode visitAlterView(final AlterViewContext ctx) {
         AlterViewStatement result = new AlterViewStatement();
         result.setView((SimpleTableSegment) visit(ctx.viewName()));
         result.setViewDefinition(getOriginalText(ctx.createOrAlterViewClause().select()));
         result.setSelect((SelectStatement) visit(ctx.createOrAlterViewClause().select()));
         return result;
     }
     
     @Override
     public ASTNode visitAlterDatabase(final AlterDatabaseContext ctx) {
         return new AlterDatabaseStatement();
     }
     
     @Override
     public ASTNode visitDropDatabase(final DropDatabaseContext ctx) {
         return new DropDatabaseStatement(null, false);
     }
     
     @Override
     public ASTNode visitDropFunction(final DropFunctionContext ctx) {
         return new DropFunctionStatement();
     }
     
     @Override
     public ASTNode visitDropProcedure(final DropProcedureContext ctx) {
         return new DropProcedureStatement();
     }
     
     @Override
     public ASTNode visitDropView(final DropViewContext ctx) {
         DropViewStatement result = new DropViewStatement();
         result.setIfExists(null != ctx.ifExists());
         for (ViewNameContext each : ctx.viewName()) {
             result.getViews().add((SimpleTableSegment) visit(each));
         }
         return result;
     }
     
     @Override
     public ASTNode visitDropTrigger(final DropTriggerContext ctx) {
         return new DropTriggerStatement();
     }
     
     @Override
     public ASTNode visitDropSequence(final DropSequenceContext ctx) {
         return new DropSequenceStatement(Collections.emptyList());
     }
 }