Merge c392dbedfd into 0b375e47ed

* fix test checkstyle

* fix testcase

* fix testcase

* fix checkstyle

.gitignore

@@ -24,3 +24,4 @@ replay_pid*.log
 
 .vscode
 druid-spring-boot-3-starter/demo-db.mv.db
+/worktrees/

QWEN.md

@@ -0,0 +1,45 @@
+# Qwen Code Context for Druid Project
+
+This document provides essential context for Qwen Code to understand and assist with the Druid project.
+
+## Project Overview
+
+This is a **Java** project. Druid is a high-performance, scalable JDBC connection pool implementation for Java applications. It's designed to provide efficient database connection management and includes features for monitoring and statistics.
+
+Key aspects:
+- **Main Technology:** Java, built with Maven.
+- **Core Functionality:** JDBC Connection Pooling (`DruidDataSource`).
+- **Additional Features:** SQL monitoring, statistics, and security features like SQL firewall (`WallFilter`).
+- **Integration:** Provides Spring Boot starters for easy integration (`druid-spring-boot-starter`, `druid-spring-boot-3-starter`).
+
+## Project Structure
+
+- `pom.xml`: Root Maven project file. Defines parent POM, manages modules, dependencies, and build profiles.
+- `core/`: Contains the main Druid library source code.
+    - `core/pom.xml`: Maven configuration for the core library.
+    - `core/src/main/java/com/alibaba/druid/`: Main source code for the Druid library.
+        - `pool/`: Core connection pooling logic (e.g., `DruidDataSource`).
+        - `sql/`: SQL parsing and analysis.
+        - `stat/`: Statistics collection and management.
+        - `wall/`: SQL firewall/filtering logic.
+        - `filter/`: Extensible filter mechanism for connections/statements.
+- `druid-spring-boot-starter/`: Spring Boot Starter for integrating Druid into Spring Boot 2.x applications.
+- `druid-spring-boot-3-starter/`: Spring Boot Starter for integrating Druid into Spring Boot 3.x applications.
+- `druid-demo-petclinic/`: A demo application, likely based on Spring PetClinic, showcasing Druid usage.
+- `doc/`: Documentation files.
+- `README.md`: General project introduction and quick start guide.
+
+## Building and Running
+
+- **Prerequisites:** Java 8+ JDK, Apache Maven.
+- **Build Command:** `mvn clean install` (from the project root). This compiles the code, runs tests, and packages the artifacts (JARs).
+- **Run Demo:** Navigate to `druid-demo-petclinic` and follow its specific instructions (likely `mvn spring-boot:run`).
+
+## Development Conventions
+
+- **Build Tool:** Apache Maven is used for dependency management and building.
+- **Language:** Java.
+- **Testing:** Unit and integration tests are likely located within `src/test` directories of respective modules (e.g., `core/src/test`). The `pom.xml` configures the `maven-surefire-plugin` to run tests.
+- **Code Style:** Checkstyle is configured (see `pom.xml` and `src/checkstyle/druid-checks.xml`) to enforce coding standards.
+- **Modularization:** The project is a multi-module Maven project, separating the core library from Spring Boot integration modules.
+- **Versioning:** Version information is managed in the root `pom.xml` and reflected in `core/src/main/java/com/alibaba/druid/VERSION.java`.

core/src/main/java/com/alibaba/druid/mock/handler/MySqlMockExecuteHandlerImpl.java

@@ -38,7 +38,7 @@ public class MySqlMockExecuteHandlerImpl implements MockExecuteHandler {
     @Override
     public ResultSet executeQuery(MockStatementBase statement, String sql) throws SQLException {
         SQLStatementParser parser = new MySqlStatementParser(sql);
-        List<SQLStatement> stmtList = parser.parseStatementList(); //
+        List<SQLStatement> stmtList = parser.parseStatementList();
 
         if (stmtList.size() > 1) {
             throw new SQLException("not support multi-statment. " + sql);

core/src/main/java/com/alibaba/druid/pool/DruidAbstractDataSource.java

@@ -73,7 +73,7 @@ public abstract class DruidAbstractDataSource extends WrapperAdapter implements
     public static final String DEFAULT_VALIDATION_QUERY = null;                                                //
     public static final boolean DEFAULT_TEST_ON_BORROW = false;
     public static final boolean DEFAULT_TEST_ON_RETURN = false;
-    public static final boolean DEFAULT_WHILE_IDLE = true;
+    public static final boolean DEFAULT_WHILE_IDLE = false;
     public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS = 60 * 1000L;
     public static final long DEFAULT_TIME_BETWEEN_CONNECT_ERROR_MILLIS = 500;
     public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN = 3;

core/src/main/java/com/alibaba/druid/pool/DruidDataSource.java

@@ -2868,7 +2868,7 @@ public class DruidDataSource extends DruidAbstractDataSource
                     if (timeBetweenEvictionRunsMillis > 0) {
                         Thread.sleep(timeBetweenEvictionRunsMillis);
                     } else {
-                        Thread.sleep(1000); //
+                        Thread.sleep(1000);
                     }
 
                     if (Thread.interrupted()) {
@@ -3149,6 +3149,9 @@ public class DruidDataSource extends DruidAbstractDataSource
 
             // shrink connections by HotSpot intrinsic function _arraycopy for performance optimization.
             int removeCount = evictCount + keepAliveCount;
+            if (removeCount > poolingCount) {
+                removeCount = poolingCount;
+            }
             if (removeCount > 0) {
                 int breakedCount = poolingCount - i;
                 if (breakedCount > 0) {
@@ -3253,7 +3256,9 @@ public class DruidDataSource extends DruidAbstractDataSource
             lock.lock();
             try {
                 int fillCount = minIdle - (activeCount + poolingCount + createTaskCount);
-                emptySignal(fillCount);
+                if (fillCount > 0) {
+                    emptySignal(fillCount);
+                }
             } finally {
                 lock.unlock();
             }

core/src/main/java/com/alibaba/druid/sql/SQLDialect.java

@@ -5,11 +5,14 @@ import com.alibaba.druid.util.FnvHash;
 import com.alibaba.druid.util.Utils;
 
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * @since 1.2.25
  */
 public class SQLDialect {
+    private static final Map<DbType, SQLDialect> DIALECTS = new ConcurrentHashMap<>();
+
     private int quoteChars;
     private final DbType dbType;
     private final Keyword keywords;
@@ -73,6 +76,13 @@ public class SQLDialect {
     }
 
     public static SQLDialect of(DbType dbType) {
+        if (dbType == null) {
+            return null;
+        }
+        return DIALECTS.computeIfAbsent(dbType, SQLDialect::create);
+    }
+
+    private static SQLDialect create(DbType dbType) {
         String dir = "META-INF/druid/parser/".concat(dbType.name().toLowerCase());
         Properties props = Utils.loadProperties(dir.concat("/dialect.properties"));
 

core/src/main/java/com/alibaba/druid/sql/SQLUtils.java

@@ -38,7 +38,7 @@ import com.alibaba.druid.sql.dialect.hive.visitor.HiveOutputVisitor;
 import com.alibaba.druid.sql.dialect.hive.visitor.HiveSchemaStatVisitor;
 import com.alibaba.druid.sql.dialect.hologres.visitor.HologresOutputVisitor;
 import com.alibaba.druid.sql.dialect.impala.visitor.ImpalaOutputVisitor;
-import com.alibaba.druid.sql.dialect.infomix.visitor.InformixOutputVisitor;
+import com.alibaba.druid.sql.dialect.informix.visitor.InformixOutputVisitor;
 import com.alibaba.druid.sql.dialect.mysql.ast.MySqlObject;
 import com.alibaba.druid.sql.dialect.mysql.ast.clause.MySqlSelectIntoStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlInsertStatement;

core/src/main/java/com/alibaba/druid/sql/dialect/athena/Athena.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.athena;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Athena {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.athena);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/athena/visitor/AthenaOutputVisitor.java

@@ -2,16 +2,17 @@ package com.alibaba.druid.sql.dialect.athena.visitor;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
+import com.alibaba.druid.sql.dialect.athena.Athena;
 import com.alibaba.druid.sql.dialect.athena.ast.stmt.AthenaCreateTableStatement;
 import com.alibaba.druid.sql.dialect.presto.visitor.PrestoOutputVisitor;
 
 public class AthenaOutputVisitor extends PrestoOutputVisitor implements AthenaASTVisitor {
     public AthenaOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.athena);
+        super(appender, DbType.athena, Athena.DIALECT);
     }
 
     public AthenaOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.athena, parameterized);
+    super(appender, DbType.athena, Athena.DIALECT, parameterized);
     }
 
     protected void printCreateTable(SQLCreateTableStatement x, boolean printSelect) {

core/src/main/java/com/alibaba/druid/sql/dialect/bigquery/parser/BigQueryLexer.java

@@ -10,8 +10,9 @@ import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.*;
 import static com.alibaba.druid.sql.parser.Token.LITERAL_CHARS;
 
 public class BigQueryLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
+    static final Keywords BIGQUERY_KEYWORDS;
+    static final DialectFeature BIGQUERY_FEATURE = new DialectFeature();
+    static {
         Map<String, Token> map = new HashMap<String, Token>();
 
         //        map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
@@ -113,7 +114,13 @@ public class BigQueryLexer extends Lexer {
         map.put("RAISE", Token.RAISE);
         map.put("ELSEIF", Token.ELSEIF);
 
-        return new Keywords(map);
+        BIGQUERY_KEYWORDS = new Keywords(map);
+        BIGQUERY_FEATURE.configFeature(SQLDateExpr, GroupByAll, InRestSpecificOperation);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return BIGQUERY_KEYWORDS;
     }
 
     public BigQueryLexer(String input, SQLParserFeature... features) {
@@ -299,8 +306,7 @@ public class BigQueryLexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(SQLDateExpr, GroupByAll, InRestSpecificOperation);
+        this.dialectFeature = BIGQUERY_FEATURE;
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/bigquery/visitor/BigQueryOutputVisitor.java

@@ -4,6 +4,7 @@ import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.bigquery.BQ;
 import com.alibaba.druid.sql.dialect.bigquery.ast.*;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 import com.alibaba.druid.util.FnvHash;
@@ -13,11 +14,11 @@ import java.util.List;
 public class BigQueryOutputVisitor extends SQLASTOutputVisitor
         implements BigQueryVisitor {
     public BigQueryOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.bigquery);
+        super(appender, DbType.bigquery, BQ.DIALECT);
     }
 
     public BigQueryOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.bigquery, parameterized);
+        super(appender, DbType.bigquery, BQ.DIALECT, parameterized);
     }
 
     protected void printPartitionedBy(SQLCreateTableStatement x) {

core/src/main/java/com/alibaba/druid/sql/dialect/blink/Blink.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.blink;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Blink {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.blink);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/blink/parser/BlinkLexer.java

@@ -10,9 +10,9 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class BlinkLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords BLINK_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -27,7 +27,12 @@ public class BlinkLexer extends Lexer {
         map.put("IF", Token.IF);
         map.put("PERIOD", Token.PERIOD);
 
-        return new Keywords(map);
+        BLINK_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return BLINK_KEYWORDS;
     }
 
     public BlinkLexer(String input) {

core/src/main/java/com/alibaba/druid/sql/dialect/blink/vsitor/BlinkOutputVisitor.java

@@ -18,6 +18,7 @@ package com.alibaba.druid.sql.dialect.blink.vsitor;
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLTableElement;
+import com.alibaba.druid.sql.dialect.blink.Blink;
 import com.alibaba.druid.sql.dialect.blink.ast.BlinkCreateTableStatement;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 
@@ -25,7 +26,7 @@ import java.util.List;
 
 public class BlinkOutputVisitor extends SQLASTOutputVisitor implements BlinkVisitor {
     public BlinkOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.blink);
+        super(appender, DbType.blink, Blink.DIALECT);
     }
 
     public BlinkOutputVisitor(StringBuilder appender, DbType dbType) {

core/src/main/java/com/alibaba/druid/sql/dialect/clickhouse/CK.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.clickhouse;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class CK {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.clickhouse);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/clickhouse/parser/CKLexer.java

@@ -1,6 +1,7 @@
 package com.alibaba.druid.sql.dialect.clickhouse.parser;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.parser.DialectFeature;
 import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.Lexer;
 import com.alibaba.druid.sql.parser.SQLParserFeature;
@@ -12,9 +13,10 @@ import java.util.Map;
 import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.*;
 
 public class CKLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords CK_KEYWORDS;
+    static final DialectFeature CK_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -41,7 +43,19 @@ public class CKLexer extends Lexer {
         map.put("CODEC", Token.CODEC);
         map.remove("ANY");
 
-        return new Keywords(map);
+        CK_KEYWORDS = new Keywords(map);
+        CK_FEATURE.configFeature(
+                AsofJoin,
+                GlobalJoin,
+                JoinRightTableAlias,
+                ParseLimitBy,
+                TableAliasAsof
+        );
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return CK_KEYWORDS;
     }
 
     public CKLexer(String input, SQLParserFeature... features) {
@@ -55,13 +69,6 @@ public class CKLexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                AsofJoin,
-                GlobalJoin,
-                JoinRightTableAlias,
-                ParseLimitBy,
-                TableAliasAsof
-        );
+        this.dialectFeature = CK_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/clickhouse/visitor/CKOutputVisitor.java

@@ -3,6 +3,7 @@ package com.alibaba.druid.sql.dialect.clickhouse.visitor;
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.clickhouse.CK;
 import com.alibaba.druid.sql.dialect.clickhouse.ast.CKAlterTableUpdateStatement;
 import com.alibaba.druid.sql.dialect.clickhouse.ast.CKCreateTableStatement;
 import com.alibaba.druid.sql.dialect.clickhouse.ast.CKSelectQueryBlock;
@@ -17,7 +18,7 @@ import java.util.List;
 
 public class CKOutputVisitor extends SQLASTOutputVisitor implements CKASTVisitor {
     public CKOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.clickhouse);
+        super(appender, DbType.clickhouse, CK.DIALECT);
     }
 
     public CKOutputVisitor(StringBuilder appender, DbType dbType) {
@@ -25,7 +26,7 @@ public class CKOutputVisitor extends SQLASTOutputVisitor implements CKASTVisitor
     }
 
     public CKOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.clickhouse, parameterized);
+        super(appender, DbType.clickhouse, CK.DIALECT, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/databricks/DataBricks.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.databricks;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class DataBricks {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.databricks);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/databricks/visitor/DatabricksOutputASTVisitor.java

@@ -2,12 +2,13 @@ package com.alibaba.druid.sql.dialect.databricks.visitor;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
+import com.alibaba.druid.sql.dialect.databricks.DataBricks;
 import com.alibaba.druid.sql.dialect.hive.stmt.HiveCreateTableStatement;
 import com.alibaba.druid.sql.dialect.spark.visitor.SparkOutputASTVisitor;
 
 public class DatabricksOutputASTVisitor extends SparkOutputASTVisitor implements DatabricksASTASTVisitor {
     public DatabricksOutputASTVisitor(StringBuilder appender) {
-        super(appender, DbType.databricks);
+        super(appender, DbType.databricks, DataBricks.DIALECT);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/db2/Db2.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.db2;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Db2 {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.db2);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/db2/parser/DB2Lexer.java

@@ -15,6 +15,7 @@
  */
 package com.alibaba.druid.sql.dialect.db2.parser;
 
+import com.alibaba.druid.sql.parser.DialectFeature;
 import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.Lexer;
 import com.alibaba.druid.sql.parser.SQLParserFeature;
@@ -26,9 +27,10 @@ import java.util.Map;
 import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.ParseAssignItemSkip;
 
 public class DB2Lexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords DB2_KEYWORDS;
+    static final DialectFeature DB2_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -48,7 +50,13 @@ public class DB2Lexer extends Lexer {
         map.put("RESTRICT", Token.RESTRICT);
         map.put("CASCADE", Token.CASCADE);
 
-        return new Keywords(map);
+        DB2_KEYWORDS = new Keywords(map);
+        DB2_FEATURE.configFeature(ParseAssignItemSkip);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return DB2_KEYWORDS;
     }
 
     public DB2Lexer(String input) {
@@ -64,7 +72,6 @@ public class DB2Lexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(ParseAssignItemSkip);
+        this.dialectFeature = DB2_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/db2/visitor/DB2OutputVisitor.java

@@ -22,16 +22,17 @@ import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.SQLAlterTableAddColumn;
 import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.db2.Db2;
 import com.alibaba.druid.sql.dialect.db2.ast.stmt.*;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 
 public class DB2OutputVisitor extends SQLASTOutputVisitor implements DB2ASTVisitor {
     public DB2OutputVisitor(StringBuilder appender) {
-        super(appender, DbType.db2);
+        super(appender, DbType.db2, Db2.DIALECT);
     }
 
     public DB2OutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.db2, parameterized);
+        super(appender, DbType.db2, Db2.DIALECT, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/doris/Doris.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.doris;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Doris {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.doris);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/doris/parser/DorisCreateTableParser.java

@@ -1,8 +1,14 @@
 package com.alibaba.druid.sql.dialect.doris.parser;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.ast.SQLPartitionBy;
+import com.alibaba.druid.sql.ast.SQLPartitionByList;
+import com.alibaba.druid.sql.ast.SQLPartitionByRange;
+import com.alibaba.druid.sql.ast.SQLPartitionByValue;
 import com.alibaba.druid.sql.dialect.starrocks.parser.StarRocksCreateTableParser;
 import com.alibaba.druid.sql.parser.SQLExprParser;
+import com.alibaba.druid.sql.parser.Token;
+import com.alibaba.druid.util.FnvHash;
 
 public class DorisCreateTableParser
         extends StarRocksCreateTableParser {
@@ -10,4 +16,54 @@ public class DorisCreateTableParser
         super(exprParser);
         dbType = DbType.doris;
     }
+
+    public SQLPartitionBy parsePartitionBy() {
+        if (lexer.nextIf(Token.PARTITION)) {
+            accept(Token.BY);
+            SQLPartitionBy partitionClause;
+            boolean hasLparen = false;
+            if (lexer.nextIfIdentifier(FnvHash.Constants.RANGE)) {
+                partitionClause = new SQLPartitionByRange();
+                accept(Token.LPAREN);
+                hasLparen = true;
+            } else if (lexer.nextIfIdentifier(FnvHash.Constants.LIST)) {
+                partitionClause = new SQLPartitionByList();
+                ((SQLPartitionByList) partitionClause).setType(SQLPartitionByList.PartitionByListType.LIST_EXPRESSION);
+                accept(Token.LPAREN);
+                hasLparen = true;
+            } else {
+                partitionClause = new SQLPartitionByValue();
+            }
+
+            for (; ;) {
+                partitionClause.addColumn(this.exprParser.expr());
+                if (lexer.nextIf(Token.COMMA)) {
+                    continue;
+                }
+                break;
+            }
+
+            if (hasLparen && !lexer.nextIf(Token.RPAREN)) {
+                accept(Token.RPAREN);
+            }
+
+            if (lexer.token() == Token.LPAREN) {
+                accept(Token.LPAREN);
+                for (; ; ) {
+                    if (lexer.token() == Token.RPAREN) {
+                        break;
+                    }
+                    partitionClause.addPartition(this.getExprParser().parsePartition());
+                    if (lexer.token() == Token.COMMA) {
+                        lexer.nextToken();
+                        continue;
+                    }
+                    break;
+                }
+                accept(Token.RPAREN);
+            }
+            return partitionClause;
+        }
+        return null;
+    }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/doris/parser/DorisLexer.java

@@ -11,9 +11,9 @@ import java.util.Map;
 
 public class DorisLexer
         extends StarRocksLexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords DORIS_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -45,7 +45,12 @@ public class DorisLexer
         map.put("RLIKE", Token.RLIKE);
         map.put("OVERWRITE", Token.OVERWRITE);
 
-        return new Keywords(map);
+        DORIS_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return DORIS_KEYWORDS;
     }
 
     public DorisLexer(String input, SQLParserFeature... features) {

core/src/main/java/com/alibaba/druid/sql/dialect/doris/visitor/DorisOutputVisitor.java

@@ -9,6 +9,7 @@ import com.alibaba.druid.sql.ast.SQLUnpivot;
 import com.alibaba.druid.sql.ast.statement.SQLInsertStatement;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.ast.statement.SQLTableSampling;
+import com.alibaba.druid.sql.dialect.doris.Doris;
 import com.alibaba.druid.sql.dialect.doris.ast.DorisExprTableSource;
 import com.alibaba.druid.sql.dialect.starrocks.visitor.StarRocksOutputVisitor;
 
@@ -16,18 +17,11 @@ import java.util.List;
 
 public class DorisOutputVisitor extends StarRocksOutputVisitor implements DorisASTVisitor {
     public DorisOutputVisitor(StringBuilder appender) {
-        super(appender);
-        dbType = DbType.doris;
-    }
-
-    public DorisOutputVisitor(StringBuilder appender, DbType dbType) {
-        super(appender, dbType);
-        dbType = DbType.doris;
+        super(appender, DbType.doris, Doris.DIALECT);
     }
 
     public DorisOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, parameterized);
-        dbType = DbType.doris;
+        super(appender, DbType.doris, Doris.DIALECT, parameterized);
     }
 
     public void printSqlSetQuantifier(SQLSelectQueryBlock x) {

core/src/main/java/com/alibaba/druid/sql/dialect/gaussdb/GaussDb.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.gaussdb;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class GaussDb {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.gaussdb);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/gaussdb/parser/GaussDbLexer.java

@@ -10,9 +10,9 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class GaussDbLexer extends PGLexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords GAUSSDB_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
         map.put("DISTRIBUTE", Token.DISTRIBUTE);
         map.put("SET", Token.SET);
         map.put("PARTITION", Token.PARTITION);
@@ -21,9 +21,14 @@ public class GaussDbLexer extends PGLexer {
         map.put("KEY", Token.KEY);
         map.put("OVERWRITE", Token.OVERWRITE);
         map.put("LOCAL", Token.LOCAL);
-        map.putAll(super.loadKeywords().getKeywords());
+        map.putAll(PGLexer.PG_KEYWORDS.getKeywords());
         map.remove("LANGUAGE"); // GaussDB does not consider it as a reserved keyword
-        return new Keywords(map);
+        GAUSSDB_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return GAUSSDB_KEYWORDS;
     }
 
     public GaussDbLexer(String input, SQLParserFeature... features) {

core/src/main/java/com/alibaba/druid/sql/dialect/gaussdb/visitor/GaussDbOutputVisitor.java

@@ -8,6 +8,7 @@ import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLInsertStatement;
 import com.alibaba.druid.sql.ast.statement.SQLWithSubqueryClause;
+import com.alibaba.druid.sql.dialect.gaussdb.GaussDb;
 import com.alibaba.druid.sql.dialect.gaussdb.ast.GaussDbDistributeBy;
 import com.alibaba.druid.sql.dialect.gaussdb.ast.GaussDbPartitionValue;
 import com.alibaba.druid.sql.dialect.gaussdb.ast.stmt.GaussDbCreateTableStatement;
@@ -21,13 +22,11 @@ import java.util.stream.Collectors;
 
 public class GaussDbOutputVisitor extends PGOutputVisitor implements GaussDbASTVisitor {
     public GaussDbOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, parameterized);
-        dbType = DbType.gaussdb;
+        super(appender, DbType.gaussdb, GaussDb.DIALECT, parameterized);
     }
 
     public GaussDbOutputVisitor(StringBuilder appender) {
-        super(appender);
-        dbType = DbType.gaussdb;
+        super(appender, DbType.gaussdb, GaussDb.DIALECT);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/h2/H2.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.h2;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class H2 {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.h2);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/h2/parser/H2Lexer.java

@@ -25,9 +25,9 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class H2Lexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords H2_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -41,7 +41,12 @@ public class H2Lexer extends Lexer {
         map.put("LIMIT", Token.LIMIT);
         map.put("IF", Token.IF);
 
-        return new Keywords(map);
+        H2_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return H2_KEYWORDS;
     }
 
     public H2Lexer(String input) {

core/src/main/java/com/alibaba/druid/sql/dialect/h2/visitor/H2OutputVisitor.java

@@ -23,6 +23,7 @@ import com.alibaba.druid.sql.ast.expr.SQLHexExpr;
 import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
 import com.alibaba.druid.sql.ast.expr.SQLQueryExpr;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.h2.H2;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlAlterTableModifyColumn;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlTableIndex;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
@@ -35,7 +36,7 @@ public class H2OutputVisitor extends SQLASTOutputVisitor implements H2ASTVisitor
     private static final Log LOG = LogFactory.getLog(H2OutputVisitor.class);
 
     public H2OutputVisitor(StringBuilder appender) {
-        super(appender, DbType.h2);
+    super(appender, DbType.h2, H2.DIALECT);
     }
 
     public H2OutputVisitor(StringBuilder appender, DbType dbType) {

core/src/main/java/com/alibaba/druid/sql/dialect/hive/Hive.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.hive;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Hive {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.hive);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveLexer.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.dialect.hive.parser;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.parser.DialectFeature;
 import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.Lexer;
 import com.alibaba.druid.sql.parser.NotAllowCommentException;
@@ -33,9 +34,10 @@ import static com.alibaba.druid.sql.parser.LayoutCharacters.EOI;
 import static com.alibaba.druid.sql.parser.Token.LITERAL_CHARS;
 
 public class HiveLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    public static final Keywords HIVE_KEYWORDS;
+    public static final DialectFeature HIVE_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -60,7 +62,30 @@ public class HiveLexer extends Lexer {
         map.put("DIV", Token.DIV);
         map.put("QUALIFY", Token.QUALIFY);
 
-        return new Keywords(map);
+        HIVE_KEYWORDS = new Keywords(map);
+        HIVE_FEATURE.configFeature(
+                ScanSQLTypeWithFrom,
+                NextTokenColon,
+                ScanAliasU,
+                JoinRightTableFrom,
+                GroupByAll,
+                SQLDateExpr,
+                ParseAssignItemRparenCommaSetReturn,
+                TableAliasLock,
+                TableAliasPartition,
+                AsSkip,
+                AsSequence,
+                AsDatabase,
+                AsDefault
+        );
+        HIVE_FEATURE.unconfigFeature(
+                PrimaryBangBangSupport
+        );
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return HIVE_KEYWORDS;
     }
 
     public HiveLexer(String input, DbType dbType) {
@@ -390,24 +415,6 @@ public class HiveLexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                ScanSQLTypeWithFrom,
-                NextTokenColon,
-                ScanAliasU,
-                JoinRightTableFrom,
-                GroupByAll,
-                SQLDateExpr,
-                ParseAssignItemRparenCommaSetReturn,
-                TableAliasLock,
-                TableAliasPartition,
-                AsSkip,
-                AsSequence,
-                AsDatabase,
-                AsDefault
-        );
-        this.dialectFeature.unconfigFeature(
-                PrimaryBangBangSupport
-        );
+        this.dialectFeature = HIVE_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/hive/visitor/HiveOutputVisitor.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.dialect.hive.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
 import com.alibaba.druid.sql.ast.SQLAdhocTableSource;
 import com.alibaba.druid.sql.ast.SQLCommentHint;
 import com.alibaba.druid.sql.ast.SQLExpr;
@@ -25,6 +26,7 @@ import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
 import com.alibaba.druid.sql.ast.expr.SQLCharExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.hive.Hive;
 import com.alibaba.druid.sql.dialect.hive.ast.HiveAddJarStatement;
 import com.alibaba.druid.sql.dialect.hive.ast.HiveInsert;
 import com.alibaba.druid.sql.dialect.hive.ast.HiveInsertStatement;
@@ -40,15 +42,19 @@ import java.util.Map;
 
 public class HiveOutputVisitor extends SQLASTOutputVisitor implements HiveASTVisitor {
     public HiveOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.hive);
+        super(appender, DbType.hive, Hive.DIALECT);
     }
 
-    public HiveOutputVisitor(StringBuilder appender, DbType dbType) {
-        super(appender, dbType);
+    public HiveOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
+        super(appender, dbType, dialect);
     }
 
     public HiveOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.hive, parameterized);
+        super(appender, DbType.hive, Hive.DIALECT, parameterized);
+    }
+
+    public HiveOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect, boolean parameterized) {
+        super(appender, DbType.hive, Hive.DIALECT, parameterized);
     }
 
     @Override
@@ -444,6 +450,9 @@ public class HiveOutputVisitor extends SQLASTOutputVisitor implements HiveASTVis
     }
 
     public boolean visit(SQLCharExpr x, boolean parameterized) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         String text = x.getText();
         if (text == null) {
             print0(ucase ? "NULL" : "null");
@@ -489,7 +498,9 @@ public class HiveOutputVisitor extends SQLASTOutputVisitor implements HiveASTVis
 
             print0(buf.toString());
         }
-
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 

core/src/main/java/com/alibaba/druid/sql/dialect/hologres/Hologres.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.hologres;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Hologres {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.hologres);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/hologres/parser/HologresLexer.java

@@ -2,16 +2,10 @@ package com.alibaba.druid.sql.dialect.hologres.parser;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.dialect.postgresql.parser.PGLexer;
-import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.SQLParserFeature;
 
 public class HologresLexer
         extends PGLexer {
-    @Override
-    protected Keywords loadKeywords() {
-        return super.loadKeywords();
-    }
-
     public HologresLexer(String input, SQLParserFeature... features) {
         super(input, features);
         dbType = DbType.hologres;

core/src/main/java/com/alibaba/druid/sql/dialect/hologres/visitor/HologresOutputVisitor.java

@@ -6,6 +6,7 @@ import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.ast.statement.SQLTableSource;
 import com.alibaba.druid.sql.dialect.clickhouse.ast.CKSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.hologres.Hologres;
 import com.alibaba.druid.sql.dialect.postgresql.visitor.PGOutputVisitor;
 import com.alibaba.druid.sql.parser.CharTypes;
 import com.alibaba.druid.sql.visitor.VisitorFeature;
@@ -14,11 +15,11 @@ import java.util.List;
 
 public class HologresOutputVisitor extends PGOutputVisitor {
     public HologresOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.hologres, parameterized);
+        super(appender, DbType.hologres, Hologres.DIALECT, parameterized);
     }
 
     public HologresOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.hologres);
+        super(appender, DbType.hologres, Hologres.DIALECT);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/impala/Impala.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.impala;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Impala {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.impala);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/impala/ast/ImpalaSQLPartitionValue.java

@@ -1,5 +1,6 @@
 package com.alibaba.druid.sql.dialect.impala.ast;
 
+import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLPartitionValue;
 
 public class ImpalaSQLPartitionValue extends SQLPartitionValue {
@@ -8,6 +9,9 @@ public class ImpalaSQLPartitionValue extends SQLPartitionValue {
     private Operator leftOperator;
     private Operator rightOperator;
 
+    public ImpalaSQLPartitionValue() {
+        super();
+    }
     public void setOperator(Operator operator) {
         this.operator = operator;
     }
@@ -50,4 +54,20 @@ public class ImpalaSQLPartitionValue extends SQLPartitionValue {
     public void setRightOperator(Operator rightOperator) {
         this.rightOperator = rightOperator;
     }
+
+    @Override
+    public ImpalaSQLPartitionValue clone() {
+        ImpalaSQLPartitionValue x = new ImpalaSQLPartitionValue();
+        x.setOperator(operator);
+        x.setLeftBound(leftBound);
+        x.setRightBound(rightBound);
+        x.setLeftOperator(leftOperator);
+        x.setRightOperator(rightOperator);
+        for (SQLExpr item : items) {
+            SQLExpr item2 = item.clone();
+            item2.setParent(x);
+            x.items.add(item2);
+        }
+        return x;
+    }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/impala/parser/ImpalaLexer.java

@@ -6,15 +6,20 @@ import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.SQLParserFeature;
 import com.alibaba.druid.sql.parser.Token;
 
+import java.util.HashMap;
 import java.util.Map;
 
 public class ImpalaLexer extends HiveLexer {
+    static final Keywords IMPALA_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>(HiveLexer.HIVE_KEYWORDS.getKeywords());
+        map.put("UPSERT", Token.UPSERT);
+        IMPALA_KEYWORDS = new Keywords(map);
+    }
+
     @Override
     protected Keywords loadKeywords() {
-        Keywords keywords = super.loadKeywords();
-        Map<String, Token> map = keywords.getKeywords();
-        map.put("UPSERT", Token.UPSERT);
-        return new Keywords(map);
+        return IMPALA_KEYWORDS;
     }
 
     public ImpalaLexer(String input) {

core/src/main/java/com/alibaba/druid/sql/dialect/impala/visitor/ImpalaOutputVisitor.java

@@ -4,6 +4,7 @@ import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.statement.*;
 import com.alibaba.druid.sql.dialect.hive.visitor.HiveOutputVisitor;
+import com.alibaba.druid.sql.dialect.impala.Impala;
 import com.alibaba.druid.sql.dialect.impala.ast.ImpalaSQLPartitionValue;
 import com.alibaba.druid.sql.dialect.impala.stmt.ImpalaCreateTableStatement;
 import com.alibaba.druid.sql.dialect.impala.stmt.ImpalaInsertStatement;
@@ -12,13 +13,11 @@ import java.util.List;
 
 public class ImpalaOutputVisitor extends HiveOutputVisitor implements ImpalaASTVisitor {
     public ImpalaOutputVisitor(StringBuilder appender) {
-        super(appender);
-        dbType = DbType.impala;
+        super(appender, DbType.impala, Impala.DIALECT);
     }
 
     public ImpalaOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, parameterized);
-        dbType = DbType.impala;
+        super(appender, DbType.impala, Impala.DIALECT, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/informix/Informix.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.informix;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Informix {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.informix);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/informix/parser/InformixSelectParser.java

@@ -1,4 +1,4 @@
-package com.alibaba.druid.sql.dialect.infomix.parser;
+package com.alibaba.druid.sql.dialect.informix.parser;
 
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;

core/src/main/java/com/alibaba/druid/sql/dialect/informix/parser/InformixStatementParser.java

@@ -1,4 +1,4 @@
-package com.alibaba.druid.sql.dialect.infomix.parser;
+package com.alibaba.druid.sql.dialect.informix.parser;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.parser.*;

core/src/main/java/com/alibaba/druid/sql/dialect/informix/visitor/InformixOutputVisitor.java

@@ -1,9 +1,10 @@
-package com.alibaba.druid.sql.dialect.infomix.visitor;
+package com.alibaba.druid.sql.dialect.informix.visitor;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLLimit;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.informix.Informix;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 
 public class InformixOutputVisitor extends SQLASTOutputVisitor {
@@ -12,7 +13,7 @@ public class InformixOutputVisitor extends SQLASTOutputVisitor {
     }
 
     public InformixOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.informix, parameterized);
+        super(appender, DbType.informix, Informix.DIALECT, parameterized);
     }
 
     protected void printSelectListBefore(SQLSelectQueryBlock x) {

core/src/main/java/com/alibaba/druid/sql/dialect/mysql/MySQL.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.mysql;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public final class MySQL {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.mysql);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlLexer.java

@@ -29,10 +29,10 @@ import static com.alibaba.druid.sql.parser.Token.LITERAL_CHARS;
 
 public class MySqlLexer extends Lexer {
     public static SymbolTable quoteTable = new SymbolTable(8192);
-
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    public static DialectFeature MYSQL_FEATURE = new DialectFeature();
+    static final Keywords MYSQL_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -67,7 +67,32 @@ public class MySqlLexer extends Lexer {
         map.put("RLIKE", Token.RLIKE);
         map.put("FULLTEXT", Token.FULLTEXT);
 
-        return new Keywords(map);
+        MYSQL_KEYWORDS = new Keywords(map);
+        MYSQL_FEATURE.configFeature(
+                NextTokenPrefixN,
+                ScanString2PutDoubleBackslash,
+                JoinRightTableWith,
+                PostNaturalJoin,
+                MultipleJoinOn,
+                GroupByPostDesc,
+                GroupByItemOrder,
+                SQLDateExpr,
+                PrimaryLbraceOdbcEscape,
+                ParseSelectItemPrefixX,
+                ParseStatementListUpdatePlanCache,
+                ParseStatementListRollbackReturn,
+                ParseStatementListCommitReturn,
+                ParseDropTableTables,
+                AsSequence
+        );
+        MYSQL_FEATURE.unconfigFeature(
+                AdditiveRestPipesAsConcat
+        );
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return MYSQL_KEYWORDS;
     }
 
     public MySqlLexer(char[] input, int inputLength, boolean skipComment) {
@@ -954,26 +979,6 @@ public class MySqlLexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                NextTokenPrefixN,
-                ScanString2PutDoubleBackslash,
-                JoinRightTableWith,
-                PostNaturalJoin,
-                MultipleJoinOn,
-                GroupByPostDesc,
-                GroupByItemOrder,
-                SQLDateExpr,
-                PrimaryLbraceOdbcEscape,
-                ParseSelectItemPrefixX,
-                ParseStatementListUpdatePlanCache,
-                ParseStatementListRollbackReturn,
-                ParseStatementListCommitReturn,
-                ParseDropTableTables,
-                AsSequence
-        );
-        this.dialectFeature.unconfigFeature(
-                AdditiveRestPipesAsConcat
-        );
+        this.dialectFeature = MYSQL_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlOutputVisitor.java

@@ -19,6 +19,7 @@ import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.mysql.MySQL;
 import com.alibaba.druid.sql.dialect.mysql.ast.*;
 import com.alibaba.druid.sql.dialect.mysql.ast.clause.*;
 import com.alibaba.druid.sql.dialect.mysql.ast.clause.ConditionValue.ConditionType;
@@ -44,11 +45,11 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     }
 
     public MySqlOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.mysql);
+        super(appender, DbType.mysql, MySQL.DIALECT);
     }
 
     public MySqlOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.mysql, parameterized);
+        super(appender, DbType.mysql, MySQL.DIALECT, parameterized);
 
         try {
             configFromProperty();
@@ -718,6 +719,9 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     }
 
     public boolean visit(SQLCharExpr x, boolean parameterized) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         if (this.appender == null) {
             return false;
         }
@@ -781,6 +785,9 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
         }
 
         appender.append('\'');
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 

core/src/main/java/com/alibaba/druid/sql/dialect/odps/Odps.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.odps;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Odps {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.odps);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/odps/parser/OdpsExprParser.java

@@ -818,4 +818,21 @@ public class OdpsExprParser extends HiveExprParser {
         }
         return super.methodRest(expr, acceptLPAREN);
     }
+
+    @Override
+    public SQLName name() {
+        SQLObject locationHolder = null;
+        if (lexer.isKeepSourceLocation()) {
+            locationHolder = new SQLIdentifierExpr("temp");
+            lexer.computeRowAndColumn(locationHolder);
+        }
+
+        SQLName name = super.name();
+
+        if (locationHolder != null) {
+            name.setSource(locationHolder.getSourceLine(), locationHolder.getSourceColumn());
+        }
+
+        return name;
+    }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/odps/parser/OdpsLexer.java

@@ -28,23 +28,10 @@ import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.*;
 import static com.alibaba.druid.sql.parser.LayoutCharacters.EOI;
 
 public class OdpsLexer extends HiveLexer {
-    public OdpsLexer(String input, SQLParserFeature... features) {
-        super(input);
-
-        init();
-
-        dbType = DbType.odps;
-        this.skipComment = true;
-        this.keepComments = false;
-
-        for (SQLParserFeature feature : features) {
-            config(feature, true);
-        }
-    }
-
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords ODPS_KEYWORDS;
+    static final DialectFeature ODPS_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -65,7 +52,76 @@ public class OdpsLexer extends HiveLexer {
         map.put("MATCHED", Token.MATCHED);
         map.put("；", Token.SEMI);
 
-        return new Keywords(map);
+        ODPS_KEYWORDS = new Keywords(map);
+        ODPS_FEATURE.configFeature(
+                ScanSQLTypeBlockComment,
+                ScanSQLTypeWithSemi,
+                ScanSQLTypeWithFunction,
+                ScanSQLTypeWithBegin,
+                ScanSQLTypeWithAt,
+                ScanVariableAt,
+                ScanVariableMoveToSemi,
+                ScanVariableSkipIdentifiers,
+                ScanNumberCommonProcess,
+                ScanHiveCommentDoubleSpace,
+                QueryRestSemi,
+                JoinAt,
+                UDJ,
+                TwoConsecutiveUnion,
+                RewriteGroupByCubeRollupToFunction,
+                PrimaryTwoConsecutiveSet,
+                ParseAllIdentifier,
+                PrimaryRestCommaAfterLparen,
+                InRestSpecificOperation,
+                ParseAssignItemEqSemiReturn,
+                ParseAssignItemEqeq,
+                ParseStatementListLparenContinue,
+                ParseRevokeFromUser,
+                ParseCreateSql,
+                TableAliasConnectWhere,
+                TableAliasTable,
+                TableAliasBetween,
+                TableAliasRest,
+                AliasLiteralFloat,
+                ScanSQLTypeWithFrom,
+                NextTokenColon,
+                ScanAliasU,
+                JoinRightTableFrom,
+                GroupByAll,
+                SQLDateExpr,
+                ParseAssignItemRparenCommaSetReturn,
+                TableAliasLock,
+                TableAliasPartition,
+                AsSkip,
+                AsSequence,
+                AsDatabase,
+                AsDefault
+        );
+        ODPS_FEATURE.unconfigFeature(
+                ParseStatementListSelectUnsupportedSyntax,
+                ScanNumberPrefixB,
+                ScanAliasU,
+                AcceptUnion,
+                PrimaryBangBangSupport
+        );
+    }
+    public OdpsLexer(String input, SQLParserFeature... features) {
+        super(input);
+
+        init();
+
+        dbType = DbType.odps;
+        this.skipComment = true;
+        this.keepComments = false;
+
+        for (SQLParserFeature feature : features) {
+            config(feature, true);
+        }
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return ODPS_KEYWORDS;
     }
 
     private void init() {
@@ -242,43 +298,6 @@ public class OdpsLexer extends HiveLexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                ScanSQLTypeBlockComment,
-                ScanSQLTypeWithSemi,
-                ScanSQLTypeWithFunction,
-                ScanSQLTypeWithBegin,
-                ScanSQLTypeWithAt,
-                ScanVariableAt,
-                ScanVariableMoveToSemi,
-                ScanVariableSkipIdentifiers,
-                ScanNumberCommonProcess,
-                ScanHiveCommentDoubleSpace,
-                QueryRestSemi,
-                JoinAt,
-                UDJ,
-                TwoConsecutiveUnion,
-                RewriteGroupByCubeRollupToFunction,
-                PrimaryTwoConsecutiveSet,
-                ParseAllIdentifier,
-                PrimaryRestCommaAfterLparen,
-                InRestSpecificOperation,
-                ParseAssignItemEqSemiReturn,
-                ParseAssignItemEqeq,
-                ParseStatementListLparenContinue,
-                ParseRevokeFromUser,
-                ParseCreateSql,
-                TableAliasConnectWhere,
-                TableAliasTable,
-                TableAliasBetween,
-                TableAliasRest,
-                AliasLiteralFloat
-        );
-        this.dialectFeature.unconfigFeature(
-                ParseStatementListSelectUnsupportedSyntax,
-                ScanNumberPrefixB,
-                ScanAliasU,
-                AcceptUnion
-        );
+        this.dialectFeature = ODPS_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/odps/visitor/OdpsOutputVisitor.java

@@ -23,6 +23,7 @@ import com.alibaba.druid.sql.ast.statement.SQLJoinTableSource.JoinType;
 import com.alibaba.druid.sql.dialect.hive.stmt.HiveCreateTableStatement;
 import com.alibaba.druid.sql.dialect.hive.stmt.HiveLoadDataStatement;
 import com.alibaba.druid.sql.dialect.hive.visitor.HiveOutputVisitor;
+import com.alibaba.druid.sql.dialect.odps.Odps;
 import com.alibaba.druid.sql.dialect.odps.ast.*;
 import com.alibaba.druid.sql.visitor.VisitorFeature;
 import com.alibaba.druid.util.FnvHash;
@@ -62,7 +63,7 @@ public class OdpsOutputVisitor extends HiveOutputVisitor implements OdpsASTVisit
     }
 
     public OdpsOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.odps);
+        super(appender, DbType.odps, Odps.DIALECT);
     }
 
     @Override
@@ -742,6 +743,9 @@ public class OdpsOutputVisitor extends HiveOutputVisitor implements OdpsASTVisit
     }
 
     public boolean visit(SQLCharExpr x, boolean parameterized) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         String text = x.getText();
         if (text == null) {
             print0(ucase ? "NULL" : "null");
@@ -772,7 +776,9 @@ public class OdpsOutputVisitor extends HiveOutputVisitor implements OdpsASTVisit
 
             print0(buf.toString());
         }
-
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 

core/src/main/java/com/alibaba/druid/sql/dialect/oracle/Oracle.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.oracle;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Oracle {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.oracle);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleLexer.java

@@ -27,8 +27,9 @@ import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.*;
 import static com.alibaba.druid.sql.parser.LayoutCharacters.EOI;
 
 public class OracleLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
+    static final Keywords ORACLE_KEYWORDS;
+    static final DialectFeature ORACLE_FEATURE = new DialectFeature();
+    static {
         Map<String, Token> map = new HashMap<>(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
         map.put("BEGIN", Token.BEGIN);
@@ -117,7 +118,20 @@ public class OracleLexer extends Lexer {
         map.put("（", Token.LPAREN);
         map.put("）", Token.RPAREN);
 
-        return new Keywords(map);
+        ORACLE_KEYWORDS = new Keywords(map);
+        ORACLE_FEATURE.configFeature(
+                ScanSQLTypeWithBegin,
+                SQLDateExpr,
+                PrimaryVariantColon,
+                CreateTableBodySupplemental,
+                AsCommaFrom
+        );
+        ORACLE_FEATURE.unconfigFeature(SQLTimestampExpr);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return ORACLE_KEYWORDS;
     }
 
     public OracleLexer(char[] input, int inputLength, boolean skipComment) {
@@ -398,14 +412,6 @@ public class OracleLexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                ScanSQLTypeWithBegin,
-                SQLDateExpr,
-                PrimaryVariantColon,
-                CreateTableBodySupplemental,
-                AsCommaFrom
-        );
-        this.dialectFeature.unconfigFeature(SQLTimestampExpr);
+        this.dialectFeature = ORACLE_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleOutputVisitor.java

@@ -21,6 +21,7 @@ import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.*;
 import com.alibaba.druid.sql.ast.statement.SQLJoinTableSource.JoinType;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlCreateTableStatement;
+import com.alibaba.druid.sql.dialect.oracle.Oracle;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalDay;
 import com.alibaba.druid.sql.dialect.oracle.ast.OracleDataTypeIntervalYear;
 import com.alibaba.druid.sql.dialect.oracle.ast.OraclePartitionSingle;
@@ -54,7 +55,7 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
     }
 
     public OracleOutputVisitor(StringBuilder appender, boolean printPostSemi) {
-        super(appender, DbType.oracle);
+        super(appender, DbType.oracle, Oracle.DIALECT);
         this.printPostSemi = printPostSemi;
     }
 

core/src/main/java/com/alibaba/druid/sql/dialect/oscar/Oscar.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.oscar;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Oscar {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.oscar);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/oscar/parser/OscarLexer.java

@@ -25,9 +25,9 @@ import static com.alibaba.druid.sql.parser.CharTypes.isIdentifierChar;
 import static com.alibaba.druid.sql.parser.Token.LITERAL_CHARS;
 
 public class OscarLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords OSCAR_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -79,7 +79,12 @@ public class OscarLexer extends Lexer {
         map.put("TEMPORARY", Token.TEMPORARY);
         map.put("TEMP", Token.TEMP);
 
-        return new Keywords(map);
+        OSCAR_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return OSCAR_KEYWORDS;
     }
 
     public OscarLexer(String input, SQLParserFeature... features) {

core/src/main/java/com/alibaba/druid/sql/dialect/oscar/visitor/OscarOutputVisitor.java

@@ -27,6 +27,7 @@ import com.alibaba.druid.sql.dialect.oracle.ast.stmt.*;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleFunctionDataType;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleProcedureDataType;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
+import com.alibaba.druid.sql.dialect.oscar.Oscar;
 import com.alibaba.druid.sql.dialect.oscar.ast.stmt.*;
 import com.alibaba.druid.sql.dialect.oscar.ast.stmt.OscarSelectQueryBlock.FetchClause;
 import com.alibaba.druid.sql.dialect.oscar.ast.stmt.OscarSelectQueryBlock.ForClause;
@@ -38,11 +39,11 @@ import java.util.Set;
 
 public class OscarOutputVisitor extends SQLASTOutputVisitor implements OscarASTVisitor, OracleASTVisitor {
     public OscarOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.oscar);
+    super(appender, DbType.oscar, Oscar.DIALECT);
     }
 
     public OscarOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.oscar, parameterized);
+        super(appender, DbType.oscar, Oscar.DIALECT, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/phoenix/Phoenix.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.phoenix;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Phoenix {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.phoenix);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/phoenix/parser/PhoenixLexer.java

@@ -28,9 +28,9 @@ import java.util.Map;
  * Created by wenshao on 16/9/13.
  */
 public class PhoenixLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    public static final Keywords PHOENIX_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -47,7 +47,12 @@ public class PhoenixLexer extends Lexer {
         map.put("MATCHED", Token.MATCHED);
         map.put("UPSERT", Token.UPSERT);
 
-        return new Keywords(map);
+        PHOENIX_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return PHOENIX_KEYWORDS;
     }
 
     public PhoenixLexer(String input, SQLParserFeature... features) {

core/src/main/java/com/alibaba/druid/sql/dialect/phoenix/visitor/PhoenixOutputVisitor.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.dialect.phoenix.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.dialect.phoenix.Phoenix;
 import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 
 /**
@@ -23,10 +24,10 @@ import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
  */
 public class PhoenixOutputVisitor extends SQLASTOutputVisitor implements PhoenixASTVisitor {
     public PhoenixOutputVisitor(StringBuilder appender) {
-    super(appender, DbType.phoenix);
+    super(appender, DbType.phoenix, Phoenix.DIALECT);
     }
 
     public PhoenixOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.phoenix, parameterized);
+        super(appender, DbType.phoenix, Phoenix.DIALECT, parameterized);
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/postgresql/PG.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.postgresql;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class PG {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.postgresql);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGLexer.java

@@ -27,9 +27,10 @@ import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.*;
 import static com.alibaba.druid.sql.parser.Token.LITERAL_CHARS;
 
 public class PGLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    public static final Keywords PG_KEYWORDS;
+    public static final DialectFeature PG_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -74,7 +75,17 @@ public class PGLexer extends Lexer {
         map.put("INTERVAL", Token.INTERVAL);
         map.put("LANGUAGE", Token.LANGUAGE);
 
-        return new Keywords(map);
+        PG_KEYWORDS = new Keywords(map);
+        PG_FEATURE.configFeature(
+                ScanVariableGreaterThan,
+                SQLDateExpr,
+                ParseStatementListWhen
+        );
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return PG_KEYWORDS;
     }
 
     public PGLexer(String input, SQLParserFeature... features) {
@@ -258,11 +269,6 @@ public class PGLexer extends Lexer {
 
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                ScanVariableGreaterThan,
-                SQLDateExpr,
-                ParseStatementListWhen
-        );
+        this.dialectFeature = PG_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/postgresql/visitor/PGOutputVisitor.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.dialect.postgresql.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
 import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.expr.*;
 import com.alibaba.druid.sql.ast.statement.*;
@@ -27,6 +28,7 @@ import com.alibaba.druid.sql.dialect.oracle.ast.stmt.*;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleFunctionDataType;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleProcedureDataType;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
+import com.alibaba.druid.sql.dialect.postgresql.PG;
 import com.alibaba.druid.sql.dialect.postgresql.ast.expr.*;
 import com.alibaba.druid.sql.dialect.postgresql.ast.stmt.*;
 import com.alibaba.druid.sql.dialect.postgresql.ast.stmt.PGSelectQueryBlock.FetchClause;
@@ -43,16 +45,16 @@ public class PGOutputVisitor extends SQLASTOutputVisitor implements PGASTVisitor
     public PGOutputVisitor(StringBuilder appender) {
         super(appender, DbType.postgresql);
     }
-    public PGOutputVisitor(StringBuilder appender, DbType dbType) {
-        super(appender, dbType);
+    public PGOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
+        super(appender, dbType, dialect);
     }
 
     public PGOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.postgresql, parameterized);
+    super(appender, DbType.postgresql, PG.DIALECT, parameterized);
     }
 
-    public PGOutputVisitor(StringBuilder appender, DbType dbType, boolean parameterized) {
-        super(appender, DbType.postgresql, parameterized);
+    public PGOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect, boolean parameterized) {
+        super(appender, dbType, dialect, parameterized);
     }
 
     @Override
@@ -2791,6 +2793,9 @@ public class PGOutputVisitor extends SQLASTOutputVisitor implements PGASTVisitor
     }
 
     public boolean visit(SQLCharExpr x, boolean parameterized) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         if (parameterized) {
             print('?');
             incrementReplaceCunt();
@@ -2823,7 +2828,9 @@ public class PGOutputVisitor extends SQLASTOutputVisitor implements PGASTVisitor
         } else {
             printChars(x.getText());
         }
-
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 

core/src/main/java/com/alibaba/druid/sql/dialect/presto/Presto.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.presto;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Presto {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.presto);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/presto/parser/PrestoLexer.java

@@ -1,6 +1,7 @@
 package com.alibaba.druid.sql.dialect.presto.parser;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.parser.DialectFeature;
 import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.Lexer;
 import com.alibaba.druid.sql.parser.SQLParserFeature;
@@ -13,9 +14,10 @@ import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.AsDataba
 import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.SQLDateExpr;
 
 public class PrestoLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords PRESTO_KEYWORDS;
+    static final DialectFeature PRESTO_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -34,7 +36,16 @@ public class PrestoLexer extends Lexer {
 
         map.put("IF", Token.IF);
 
-        return new Keywords(map);
+        PRESTO_KEYWORDS = new Keywords(map);
+        PRESTO_FEATURE.configFeature(
+                SQLDateExpr,
+                AsDatabase
+        );
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return PRESTO_KEYWORDS;
     }
 
     public PrestoLexer(String input, DbType dbType, SQLParserFeature... features) {
@@ -49,10 +60,6 @@ public class PrestoLexer extends Lexer {
     }
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                SQLDateExpr,
-                AsDatabase
-        );
+        this.dialectFeature = PRESTO_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/presto/visitor/PrestoOutputVisitor.java

@@ -16,11 +16,13 @@
 package com.alibaba.druid.sql.dialect.presto.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLLimit;
 import com.alibaba.druid.sql.ast.expr.SQLArrayExpr;
 import com.alibaba.druid.sql.ast.expr.SQLDecimalExpr;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.presto.Presto;
 import com.alibaba.druid.sql.dialect.presto.ast.PrestoColumnWith;
 import com.alibaba.druid.sql.dialect.presto.ast.PrestoDateTimeExpr;
 import com.alibaba.druid.sql.dialect.presto.ast.stmt.PrestoAlterFunctionStatement;
@@ -44,15 +46,19 @@ public class PrestoOutputVisitor extends SQLASTOutputVisitor implements PrestoAS
     }
 
     public PrestoOutputVisitor(StringBuilder appender, DbType dbType) {
-        super(appender, dbType);
+        super(appender, dbType, Presto.DIALECT);
+    }
+
+    public PrestoOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
+        super(appender, dbType, dialect);
     }
 
     public PrestoOutputVisitor(StringBuilder appender, boolean parameterized) {
-        this(appender, DbType.presto, parameterized);
+        this(appender, DbType.presto, Presto.DIALECT, parameterized);
     }
 
-    public PrestoOutputVisitor(StringBuilder appender, DbType dbType, boolean parameterized) {
-        super(appender, dbType, parameterized);
+    public PrestoOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect, boolean parameterized) {
+        super(appender, dbType, dialect, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/redshift/Redshift.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.redshift;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Redshift {
+    public static final SQLDialect dialect = SQLDialect.of(DbType.redshift);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/redshift/parser/RedshiftLexer.java

@@ -11,9 +11,9 @@ import java.util.Map;
 
 public class RedshiftLexer
         extends PGLexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords REDSHIFT_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -73,7 +73,12 @@ public class RedshiftLexer
         map.put("SORTKEY", Token.SORTKEY);
         map.put("BACKUP", Token.BACKUP);
 
-        return new Keywords(map);
+        REDSHIFT_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return REDSHIFT_KEYWORDS;
     }
 
     public RedshiftLexer(String input, SQLParserFeature... features) {

core/src/main/java/com/alibaba/druid/sql/dialect/redshift/visitor/RedshiftOutputVisitor.java

@@ -8,17 +8,16 @@ import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.ast.statement.SQLExprTableSource;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.postgresql.visitor.PGOutputVisitor;
+import com.alibaba.druid.sql.dialect.redshift.Redshift;
 import com.alibaba.druid.sql.dialect.redshift.stmt.*;
 
 public class RedshiftOutputVisitor extends PGOutputVisitor implements RedshiftASTVisitor {
     public RedshiftOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, parameterized);
-        dbType = DbType.hologres;
+        super(appender, DbType.redshift, Redshift.dialect, parameterized);
     }
 
     public RedshiftOutputVisitor(StringBuilder appender) {
-        super(appender);
-        dbType = DbType.hologres;
+        super(appender, DbType.redshift, Redshift.dialect);
     }
 
     public boolean visit(RedshiftSelectQueryBlock x) {

core/src/main/java/com/alibaba/druid/sql/dialect/spark/Spark.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.spark;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Spark {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.spark);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/spark/ast/SparkCreateTableStatement.java

@@ -8,8 +8,8 @@ import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLObject;
 import com.alibaba.druid.sql.ast.statement.SQLAssignItem;
-import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLExprTableSource;
+import com.alibaba.druid.sql.dialect.hive.stmt.HiveCreateTableStatement;
 import com.alibaba.druid.sql.dialect.spark.visitor.SparkASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
@@ -22,7 +22,7 @@ import java.util.Map;
  * @author peiheng.qph
  * @version $Id: AntsparkCreateTableStatement.java, v 0.1 2018年09月14日 15:02 peiheng.qph Exp $
  */
-public class SparkCreateTableStatement extends SQLCreateTableStatement {
+public class SparkCreateTableStatement extends HiveCreateTableStatement {
     protected List<SQLAssignItem> mappedBy = new ArrayList<SQLAssignItem>(1);
     protected List<SQLExpr> skewedBy = new ArrayList<SQLExpr>();
     protected List<SQLExpr> skewedByOn = new ArrayList<SQLExpr>();

core/src/main/java/com/alibaba/druid/sql/dialect/spark/parser/SparkLexer.java

@@ -6,6 +6,7 @@ package com.alibaba.druid.sql.dialect.spark.parser;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.dialect.hive.parser.HiveLexer;
+import com.alibaba.druid.sql.parser.DialectFeature;
 import com.alibaba.druid.sql.parser.Keywords;
 import com.alibaba.druid.sql.parser.SQLParserFeature;
 import com.alibaba.druid.sql.parser.Token;
@@ -13,15 +14,19 @@ import com.alibaba.druid.sql.parser.Token;
 import java.util.HashMap;
 import java.util.Map;
 
+import static com.alibaba.druid.sql.parser.DialectFeature.LexerFeature.NextTokenColon;
+import static com.alibaba.druid.sql.parser.DialectFeature.LexerFeature.ScanAliasU;
+import static com.alibaba.druid.sql.parser.DialectFeature.LexerFeature.ScanSQLTypeWithFrom;
 import static com.alibaba.druid.sql.parser.DialectFeature.ParserFeature.*;
 /**
  * @author peiheng.qph
  * @version $Id: AntsparkLexer.java, v 0.1 2018年09月14日 15:04 peiheng.qph Exp $
  */
 public class SparkLexer extends HiveLexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords SPARK_KEYWORDS;
+    static final DialectFeature SPARK_FEATURE = new DialectFeature();
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -47,7 +52,33 @@ public class SparkLexer extends HiveLexer {
         map.put("QUALIFY", Token.QUALIFY);
         map.put("OR", Token.OR);
 
-        return new Keywords(map);
+        SPARK_KEYWORDS = new Keywords(map);
+        SPARK_FEATURE.configFeature(
+                QueryTable,
+                ParseSelectItemPrefixX,
+                JoinRightTableFrom,
+                ScanSQLTypeWithFrom,
+                NextTokenColon,
+                ScanAliasU,
+                JoinRightTableFrom,
+                GroupByAll,
+                SQLDateExpr,
+                ParseAssignItemRparenCommaSetReturn,
+                TableAliasLock,
+                TableAliasPartition,
+                AsSkip,
+                AsSequence,
+                AsDatabase,
+                AsDefault
+        );
+        SPARK_FEATURE.unconfigFeature(
+                PrimaryBangBangSupport
+        );
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return SPARK_KEYWORDS;
     }
 
     public SparkLexer(String input) {
@@ -66,11 +97,6 @@ public class SparkLexer extends HiveLexer {
     }
     @Override
     protected void initDialectFeature() {
-        super.initDialectFeature();
-        this.dialectFeature.configFeature(
-                QueryTable,
-                ParseSelectItemPrefixX,
-                JoinRightTableFrom
-        );
+        this.dialectFeature = SPARK_FEATURE;
     }
 }

core/src/main/java/com/alibaba/druid/sql/dialect/spark/visitor/SparkOutputASTVisitor.java

@@ -5,12 +5,14 @@
 package com.alibaba.druid.sql.dialect.spark.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLObject;
 import com.alibaba.druid.sql.ast.expr.SQLHexExpr;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
 import com.alibaba.druid.sql.dialect.hive.visitor.HiveOutputVisitor;
+import com.alibaba.druid.sql.dialect.spark.Spark;
 import com.alibaba.druid.sql.dialect.spark.ast.SparkCreateTableStatement;
 import com.alibaba.druid.sql.dialect.spark.ast.stmt.SparkCacheTableStatement;
 import com.alibaba.druid.sql.dialect.spark.ast.stmt.SparkCreateScanStatement;
@@ -24,12 +26,12 @@ import java.util.Map.Entry;
  * @version $Id: SparkOutputVisitor.java, v 0.1 2018年09月17日 10:40 peiheng.qph Exp $
  */
 public class SparkOutputASTVisitor extends HiveOutputVisitor implements SparkASTVisitor {
-    public SparkOutputASTVisitor(StringBuilder appender, DbType dbType) {
-        super(appender, dbType);
+    public SparkOutputASTVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
+        super(appender, dbType, dialect);
     }
 
     public SparkOutputASTVisitor(StringBuilder appender) {
-        super(appender);
+        super(appender, DbType.spark, Spark.DIALECT);
     }
 
     //add using statment

core/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/SqlServer.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.sqlserver;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class SqlServer {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.sqlserver);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerLexer.java

@@ -25,9 +25,9 @@ import static com.alibaba.druid.sql.parser.LayoutCharacters.EOI;
 import static com.alibaba.druid.sql.parser.Token.IDENTIFIER;
 
 public class SQLServerLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords SQLSERVER_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -48,7 +48,12 @@ public class SQLServerLexer extends Lexer {
         map.put("MATCHED", Token.MATCHED);
         map.put("OPTION", Token.OPTION);
 
-        return new Keywords(map);
+        SQLSERVER_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return SQLSERVER_KEYWORDS;
     }
 
     public SQLServerLexer(char[] input, int inputLength, boolean skipComment) {

core/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/visitor/SQLServerOutputVisitor.java

@@ -16,10 +16,12 @@
 package com.alibaba.druid.sql.dialect.sqlserver.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
 import com.alibaba.druid.sql.ast.*;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLSequenceExpr;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.sql.dialect.sqlserver.SqlServer;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.SQLServerOutput;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.SQLServerSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.expr.SQLServerObjectReferenceExpr;
@@ -33,13 +35,20 @@ import java.util.List;
 
 public class SQLServerOutputVisitor extends SQLASTOutputVisitor implements SQLServerASTVisitor {
     public SQLServerOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.sqlserver);
+        super(appender, DbType.sqlserver, SqlServer.DIALECT);
+    }
+
+    public SQLServerOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
+        super(appender, dbType, dialect);
     }
 
     public SQLServerOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.sqlserver, parameterized);
+        super(appender, DbType.sqlserver, SqlServer.DIALECT, parameterized);
     }
 
+    public SQLServerOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect, boolean parameterized) {
+        super(appender, dbType, dialect, parameterized);
+    }
     public boolean visit(SQLServerSelectQueryBlock x) {
         print0(ucase ? "SELECT " : "select ");
 

core/src/main/java/com/alibaba/druid/sql/dialect/starrocks/StarRocks.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.starrocks;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class StarRocks {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.starrocks);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/starrocks/parser/StarRocksLexer.java

@@ -10,9 +10,9 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class StarRocksLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords STARROCKS_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -37,7 +37,12 @@ public class StarRocksLexer extends Lexer {
         map.put("RLIKE", Token.RLIKE);
         map.put("USING", Token.USING);
         map.put("OVERWRITE", Token.OVERWRITE);
-        return new Keywords(map);
+        STARROCKS_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return STARROCKS_KEYWORDS;
     }
 
     public StarRocksLexer(String input) {

core/src/main/java/com/alibaba/druid/sql/dialect/starrocks/visitor/StarRocksOutputVisitor.java

@@ -1,6 +1,7 @@
 package com.alibaba.druid.sql.dialect.starrocks.visitor;
 
 import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
 import com.alibaba.druid.sql.ast.DistributedByType;
 import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
@@ -15,6 +16,7 @@ import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLNotNullConstraint;
 import com.alibaba.druid.sql.ast.statement.SQLNullConstraint;
 import com.alibaba.druid.sql.ast.statement.SQLPrimaryKeyImpl;
+import com.alibaba.druid.sql.dialect.starrocks.StarRocks;
 import com.alibaba.druid.sql.dialect.starrocks.ast.StarRocksAggregateKey;
 import com.alibaba.druid.sql.dialect.starrocks.ast.StarRocksDuplicateKey;
 import com.alibaba.druid.sql.dialect.starrocks.ast.StarRocksIndexDefinition;
@@ -33,15 +35,19 @@ public class StarRocksOutputVisitor extends SQLASTOutputVisitor implements StarR
     }
 
     public StarRocksOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.starrocks);
+        super(appender, DbType.starrocks, StarRocks.DIALECT);
     }
 
-    public StarRocksOutputVisitor(StringBuilder appender, DbType dbType) {
-        super(appender, dbType);
+    public StarRocksOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
+        super(appender, dbType, dialect);
     }
 
     public StarRocksOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.starrocks, parameterized);
+        super(appender, DbType.starrocks, StarRocks.DIALECT, parameterized);
+    }
+
+    public StarRocksOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect, boolean parameterized) {
+        super(appender, dbType, dialect, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/supersql/SuperSql.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.supersql;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class SuperSql {
+    public static final SQLDialect DIALECT = SQLDialect.of(DbType.supersql);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/supersql/parser/SuperSqlLexer.java

@@ -10,9 +10,9 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class SuperSqlLexer extends PrestoLexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords SUPERSQL_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
         map.put("FETCH", Token.FETCH);
         map.put("FIRST", Token.FIRST);
@@ -32,8 +32,14 @@ public class SuperSqlLexer extends PrestoLexer {
         map.put("PARTITIONED", Token.PARTITIONED);
         map.put("RLIKE", Token.RLIKE);
 
-        return new Keywords(map);
+        SUPERSQL_KEYWORDS = new Keywords(map);
     }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return SUPERSQL_KEYWORDS;
+    }
+
     public SuperSqlLexer(String input, SQLParserFeature... features) {
         super(input, features);
         this.dbType = DbType.supersql;

core/src/main/java/com/alibaba/druid/sql/dialect/supersql/visitor/SuperSqlOutputVisitor.java

@@ -3,14 +3,15 @@ package com.alibaba.druid.sql.dialect.supersql.visitor;
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.ast.statement.SQLInsertStatement;
 import com.alibaba.druid.sql.dialect.presto.visitor.PrestoOutputVisitor;
+import com.alibaba.druid.sql.dialect.supersql.SuperSql;
 
 public class SuperSqlOutputVisitor extends PrestoOutputVisitor implements SuperSqlASTVisitor {
     public SuperSqlOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.supersql);
+        super(appender, DbType.supersql, SuperSql.DIALECT);
     }
 
     public SuperSqlOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, DbType.supersql, parameterized);
+        super(appender, DbType.supersql, SuperSql.DIALECT, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/synapse/Synapse.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.synapse;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class Synapse {
+    public static final SQLDialect dialect = SQLDialect.of(DbType.synapse);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/synapse/visitor/SynapseOutputVisitor.java

@@ -2,17 +2,16 @@ package com.alibaba.druid.sql.dialect.synapse.visitor;
 
 import com.alibaba.druid.DbType;
 import com.alibaba.druid.sql.dialect.sqlserver.visitor.SQLServerOutputVisitor;
+import com.alibaba.druid.sql.dialect.synapse.Synapse;
 import com.alibaba.druid.sql.dialect.synapse.ast.stmt.SynapseCreateTableStatement;
 
 public class SynapseOutputVisitor extends SQLServerOutputVisitor implements SynapseASTVisitor {
     public SynapseOutputVisitor(StringBuilder appender) {
-        super(appender);
-        dbType = DbType.synapse;
+        super(appender, DbType.synapse, Synapse.dialect);
     }
 
     public SynapseOutputVisitor(StringBuilder appender, boolean parameterized) {
-        super(appender, parameterized);
-        dbType = DbType.synapse;
+        super(appender, DbType.synapse, Synapse.dialect, parameterized);
     }
 
     @Override

core/src/main/java/com/alibaba/druid/sql/dialect/teradata/TeraData.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.teradata;
+
+import com.alibaba.druid.DbType;
+import com.alibaba.druid.sql.SQLDialect;
+
+public class TeraData {
+    public static final SQLDialect dialect = SQLDialect.of(DbType.teradata);
+}

core/src/main/java/com/alibaba/druid/sql/dialect/teradata/parser/TDLexer.java

@@ -10,9 +10,9 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class TDLexer extends Lexer {
-    @Override
-    protected Keywords loadKeywords() {
-        Map<String, Token> map = new HashMap<String, Token>();
+    static final Keywords TERADATA_KEYWORDS;
+    static {
+        Map<String, Token> map = new HashMap<>();
 
         map.putAll(Keywords.DEFAULT_KEYWORDS.getKeywords());
 
@@ -20,7 +20,12 @@ public class TDLexer extends Lexer {
         map.put("TOP", Token.TOP);
         map.put("QUALIFY", Token.QUALIFY);
 
-        return new Keywords(map);
+        TERADATA_KEYWORDS = new Keywords(map);
+    }
+
+    @Override
+    protected Keywords loadKeywords() {
+        return TERADATA_KEYWORDS;
     }
 
     public TDLexer(String input, SQLParserFeature... features) {

core/src/main/java/com/alibaba/druid/sql/dialect/teradata/visitor/TDOutputVisitor.java

@@ -7,6 +7,7 @@ import com.alibaba.druid.sql.ast.SQLTop;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLPrimaryKeyImpl;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.teradata.TeraData;
 import com.alibaba.druid.sql.dialect.teradata.ast.TDCreateTableStatement;
 import com.alibaba.druid.sql.dialect.teradata.ast.TDDateDataType;
 import com.alibaba.druid.sql.dialect.teradata.ast.TDNormalize;
@@ -15,7 +16,7 @@ import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;
 
 public class TDOutputVisitor extends SQLASTOutputVisitor implements TDASTVisitor {
     public TDOutputVisitor(StringBuilder appender) {
-        super(appender, DbType.teradata);
+        super(appender, DbType.teradata, TeraData.dialect);
     }
 
     protected void printSelectListBefore(SQLSelectQueryBlock x) {

core/src/main/java/com/alibaba/druid/sql/parser/Lexer.java

@@ -39,6 +39,7 @@ import static com.alibaba.druid.sql.parser.Token.*;
  * @author wenshao [szujobs@hotmail.com]
  */
 public class Lexer {
+    protected static final DialectFeature FEATURE = new DialectFeature();
     protected static SymbolTable symbols_l2 = new SymbolTable(512);
 
     protected int features; //SQLParserFeature.of(SQLParserFeature.EnableSQLBinaryOpExprGroup);
@@ -265,7 +266,7 @@ public class Lexer {
     }
 
     protected void initDialectFeature() {
-        this.dialectFeature = new DialectFeature();
+        this.dialectFeature = FEATURE;
     }
 
     public Lexer(char[] input, int inputLength, boolean skipComment) {
@@ -2278,7 +2279,6 @@ public class Lexer {
         if (ch != ':' && ch != '#' && ch != '$' && !(ch == '@' && dialectFeatureEnabled(ScanVariableAt))) {
             throw new ParserException("illegal variable. " + info());
         }
-        boolean templateParameter = false;
         mark = pos;
         bufPos = 1;
         char ch;
@@ -2296,14 +2296,13 @@ public class Lexer {
             boolean ident = false;
             for (; ; ) {
                 ch = charAt(++pos);
-                if (isEOF() || (templateParameter && (ch == ';' || ch == '；' || ch == '\r'))) {
+                if (isEOF() || ch == ';' || ch == '；' || ch == '\r' || ch == '\n') {
                     pos--;
                     bufPos--;
                     break;
                 }
 
                 if (ch == '}' && !ident) {
-                    templateParameter = false;
                     if (isIdentifierChar(charAt(pos + 1))) {
                         bufPos++;
                         ident = true;
@@ -2314,7 +2313,6 @@ public class Lexer {
 
                 if (ident && ch == '$') {
                     if (charAt(pos + 1) == '{') {
-                        templateParameter = true;
                         bufPos++;
                         ident = false;
                         continue;

core/src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java

@@ -1265,8 +1265,7 @@ public class SQLExprParser extends SQLParser {
             expr.addBeforeComment(beforeComments);
         }
         if (lexer.hasComment() && lexer.isKeepComments()) {
-            // @todo 是否保留注释，暂时待定，因为保留的话，有20来个测试用例会失败 by lizongbo
-            // expr.addAfterComment(lexer.readAndResetComments());
+             expr.addAfterComment(lexer.readAndResetComments());
         }
         return expr;
     }
@@ -3223,6 +3222,7 @@ public class SQLExprParser extends SQLParser {
                             }
                             continue;
                         }
+                        item.addAfterComment(lexer.comments);
                         break;
                     }
 

core/src/main/java/com/alibaba/druid/sql/parser/SQLParserUtils.java

@@ -57,7 +57,7 @@ import com.alibaba.druid.sql.dialect.hologres.parser.HologresStatementParser;
 import com.alibaba.druid.sql.dialect.impala.parser.ImpalaExprParser;
 import com.alibaba.druid.sql.dialect.impala.parser.ImpalaLexer;
 import com.alibaba.druid.sql.dialect.impala.parser.ImpalaStatementParser;
-import com.alibaba.druid.sql.dialect.infomix.parser.InformixStatementParser;
+import com.alibaba.druid.sql.dialect.informix.parser.InformixStatementParser;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.parser.MySqlExprParser;
 import com.alibaba.druid.sql.dialect.mysql.parser.MySqlLexer;
@@ -730,7 +730,7 @@ public class SQLParserUtils {
                 set = true;
             }
 
-            if (lexer.identifierEquals("ADD") && (dbType == DbType.hive || dbType == DbType.odps)) {
+            if (lexer.identifierEquals("ADD") && (dbType == DbType.hive || dbType == DbType.odps || dbType == DbType.spark)) {
                 lexer.nextToken();
                 if (lexer.identifierEquals("JAR")) {
                     lexer.nextPath();
@@ -902,7 +902,7 @@ public class SQLParserUtils {
             }
 
             prePos = lexer.pos;
-            if (lexer.identifierEquals("ADD") && (dbType == DbType.hive || dbType == DbType.odps)) {
+            if (lexer.identifierEquals("ADD") && (dbType == DbType.hive || dbType == DbType.odps || dbType == DbType.spark)) {
                 lexer.nextToken();
                 if (lexer.identifierEquals("JAR")) {
                     lexer.nextPath();

core/src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java

@@ -1129,7 +1129,9 @@ public class SQLSelectParser extends SQLParser {
         final List<SQLSelectItem> selectList = queryBlock.getSelectList();
         boolean hasComma = true;
         for (; ; ) {
+            List<String> previousComments = lexer.comments;
             final SQLSelectItem selectItem = this.exprParser.parseSelectItem();
+            selectItem.addBeforeComment(previousComments);
             selectList.add(selectItem);
             selectItem.setParent(queryBlock);
             if (!hasComma && selectItem.getExpr() instanceof SQLVariantRefExpr) {

core/src/main/java/com/alibaba/druid/sql/visitor/ParameterizedOutputVisitorUtils.java

@@ -29,7 +29,7 @@ import com.alibaba.druid.sql.dialect.clickhouse.visitor.CKOutputVisitor;
 import com.alibaba.druid.sql.dialect.db2.visitor.DB2OutputVisitor;
 import com.alibaba.druid.sql.dialect.h2.visitor.H2OutputVisitor;
 import com.alibaba.druid.sql.dialect.hologres.visitor.HologresOutputVisitor;
-import com.alibaba.druid.sql.dialect.infomix.visitor.InformixOutputVisitor;
+import com.alibaba.druid.sql.dialect.informix.visitor.InformixOutputVisitor;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlInsertStatement;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlASTVisitor;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlOutputVisitor;

core/src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java

@@ -120,19 +120,29 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public SQLASTOutputVisitor(StringBuilder appender, DbType dbType) {
+        this(appender, dbType, SQLDialect.of(dbType));
+    }
+
+    public SQLASTOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect) {
         this.appender = appender;
         this.dbType = dbType;
-        this.dialect = SQLDialect.of(dbType);
+        this.dialect = dialect;
     }
 
     public SQLASTOutputVisitor(StringBuilder appender, boolean parameterized) {
         this.appender = appender;
+        this.dialect = SQLDialect.of(dbType);
         this.config(VisitorFeature.OutputParameterized, parameterized);
     }
+
     public SQLASTOutputVisitor(StringBuilder appender, DbType dbType, boolean parameterized) {
+        this(appender, dbType, SQLDialect.of(dbType), parameterized);
+    }
+
+    public SQLASTOutputVisitor(StringBuilder appender, DbType dbType, SQLDialect dialect, boolean parameterized) {
         this.appender = appender;
         this.dbType = dbType;
-        this.dialect = SQLDialect.of(dbType);
+        this.dialect = dialect;
         this.config(VisitorFeature.OutputParameterized, parameterized);
     }
 
@@ -556,6 +566,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         this.indentCount++;
         for (int i = 0, lineItemCount = 0, size = selectList.size(); i < size; ++i, ++lineItemCount) {
             SQLSelectItem selectItem = selectList.get(i);
+            if (selectItem.hasBeforeComment()) {
+                printlnComments(selectItem.getBeforeCommentsDirect());
+            }
             SQLExpr selectItemExpr = selectItem.getExpr();
 
             int paramCount = paramCount(selectItemExpr);
@@ -987,11 +1000,17 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             printOperator(operator);
             print(' ');
             Number number = ((SQLIntegerExpr) right).getNumber();
+            if (right.hasBeforeComment()) {
+                printlnComments(right.getBeforeCommentsDirect());
+            }
             if (number instanceof BigInteger) {
                 print0(((BigInteger) number).toString());
             } else {
                 print(number.longValue());
             }
+            if (right.hasAfterComment()) {
+                printAfterComments(right.getAfterCommentsDirect());
+            }
             return false;
         }
 
@@ -1016,10 +1035,6 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
                 }
             }
 
-            if (isPrettyFormat() && item.hasBeforeComment() && !parameterized) {
-                printlnComments(item.getBeforeCommentsDirect());
-            }
-
             visitBinaryLeft(item, operator);
 
 //            if (isPrettyFormat() && item.hasAfterComment()) {
@@ -1038,7 +1053,7 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
 
             boolean printOpSpace = true;
             if (relational) {
-                if (dbType == DbType.hive && x.getParent() instanceof SQLMethodInvokeExpr) {
+                if ((DbType.hive == dbType || DbType.spark == dbType) && x.getParent() instanceof SQLMethodInvokeExpr) {
                     print(' ');
                 } else {
                     println();
@@ -1076,9 +1091,6 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     private void visitorBinaryRight(SQLBinaryOpExpr x) {
         SQLExpr right = x.getRight();
         SQLBinaryOperator op = x.getOperator();
-        if (isPrettyFormat() && right.hasBeforeComment()) {
-            printlnComments(right.getBeforeCommentsDirect());
-        }
         if (right instanceof SQLBinaryOpExpr) {
             SQLBinaryOpExpr binaryRight = (SQLBinaryOpExpr) right;
             SQLBinaryOperator rightOp = binaryRight.getOperator();
@@ -1126,11 +1138,6 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             printExpr(right, parameterized);
         }
 
-        if (right.hasAfterComment() && isPrettyFormat()) {
-            print(' ');
-            printlnComment(right.getAfterCommentsDirect());
-        }
-
         if (x.getHint() != null) {
             x.getHint().accept(this);
         }
@@ -1453,6 +1460,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public boolean visit(SQLCharExpr x, boolean parameterized) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         if (x.isParenthesized()) {
             print('(');
         }
@@ -1469,6 +1479,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         if (x.isParenthesized()) {
             print(')');
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -1569,6 +1582,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public boolean visit(SQLIdentifierExpr x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         if (x.isParenthesized()) {
             print('(');
         }
@@ -1592,6 +1608,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         if (x.isParenthesized()) {
             print(')');
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -1949,6 +1968,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public boolean visit(SQLIntegerExpr x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         boolean parameterized = this.parameterized;
         if (x.isParenthesized() && !parameterized) {
             print('(');
@@ -1957,12 +1979,18 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         if (x.isParenthesized() && !parameterized) {
             print(')');
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
     private static final Integer ONE = Integer.valueOf(1);
 
     protected void printInteger(SQLIntegerExpr x, boolean parameterized) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         Number number = x.getNumber();
         if (number.equals(ONE)) {
             if (DbType.oracle.equals(dbType)) {
@@ -1976,6 +2004,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
                         String name = ((SQLIdentifierExpr) left).getName();
                         if ("rownum".equals(name)) {
                             print(1);
+                            if (x.hasAfterComment()) {
+                                printAfterComments(x.getAfterCommentsDirect());
+                            }
                             return;
                         }
                     }
@@ -2003,6 +2034,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             if (this.parameters != null) {
                 ExportParameterVisitorUtils.exportParameter(this.parameters, x);
             }
+            if (x.hasAfterComment()) {
+                printAfterComments(x.getAfterCommentsDirect());
+            }
             return;
         }
 
@@ -2011,9 +2045,15 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         } else {
             print(number.longValue());
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
     }
 
     public boolean visit(SQLMethodInvokeExpr x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         if (x.isParenthesized()) {
             print('(');
         }
@@ -2035,6 +2075,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
                 }
 
                 replaceCount++;
+                if (x.hasAfterComment()) {
+                    printAfterComments(x.getAfterCommentsDirect());
+                }
                 return false;
             }
         }
@@ -2047,6 +2090,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         if (x.isParenthesized()) {
             print(')');
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -2369,6 +2415,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public boolean visit(SQLNullExpr x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         SQLObject parent = x.getParent();
         if (this.parameterized
                 && (parent instanceof ValuesClause || parent instanceof SQLInListExpr ||
@@ -2383,10 +2432,16 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
                     this.getParameters().add(null);
                 }
             }
+            if (x.hasAfterComment()) {
+                printAfterComments(x.getAfterCommentsDirect());
+            }
             return false;
         }
 
         print0(ucase ? "NULL" : "null");
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -2406,6 +2461,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public boolean visit(SQLPropertyExpr x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         SQLExpr owner = x.getOwner();
 
         String mapTableName = null, ownerName = null;
@@ -2461,6 +2519,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         } else {
             printName0(name);
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -3174,6 +3235,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             final String name = identifierExpr.getName();
             if (!this.parameterized) {
                 printName0(name, false);
+                if (identifierExpr.hasAfterComment()) {
+                    printAfterComments(identifierExpr.getAfterCommentsDirect());
+                }
                 return;
             }
 
@@ -3191,6 +3255,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             } else {
                 printName0(name);
             }
+            if (identifierExpr.hasAfterComment()) {
+                printAfterComments(identifierExpr.getAfterCommentsDirect());
+            }
         } else if (expr instanceof SQLPropertyExpr) {
             SQLPropertyExpr propertyExpr = (SQLPropertyExpr) expr;
             SQLExpr owner = propertyExpr.getOwner();
@@ -3333,10 +3400,16 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     }
 
     public boolean visit(SQLVariantRefExpr x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         int index = x.getIndex();
 
         if (index < 0 || inputParameters == null || index >= inputParameters.size()) {
             print0(x.getName());
+            if (x.hasAfterComment()) {
+                printAfterComments(x.getAfterCommentsDirect());
+            }
             return false;
         }
 
@@ -3370,6 +3443,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         } else {
             printParameter(param);
         }
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -4596,6 +4672,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     protected void printJoinHint(SQLJoinTableSource x){}
     @Override
     public boolean visit(SQLJoinTableSource x) {
+        if (x.hasBeforeComment()) {
+            printlnComments(x.getBeforeCommentsDirect());
+        }
         SQLCommentHint hint = x.getHint();
         if (hint != null) {
             hint.accept(this);
@@ -4704,6 +4783,9 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
 
         printPivot(x.getPivot());
         printUnpivot(x.getUnpivot());
+        if (x.hasAfterComment()) {
+            printAfterComments(x.getAfterCommentsDirect());
+        }
         return false;
     }
 
@@ -5209,7 +5291,7 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     public boolean visit(SQLAlterTableAddColumn x) {
         print0(ucase ? "ADD" : "add");
 
-        if (DbType.odps == dbType || DbType.hive == dbType) {
+        if (DbType.odps == dbType || DbType.hive == dbType || DbType.spark == dbType) {
             print0(ucase ? " COLUMNS" : " columns");
         }
 
@@ -5440,7 +5522,7 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
                     || dbType == DbType.mariadb) {
                 println();
                 print0(ucase ? "WITH (" : "with (");
-            } else if (dbType == DbType.hive || dbType == DbType.presto || dbType == DbType.trino || dbType == DbType.supersql) {
+            } else if (dbType == DbType.hive || dbType == DbType.presto || dbType == DbType.trino || dbType == DbType.supersql || dbType == DbType.spark) {
                 println();
                 print0(ucase ? "WITH DBPROPERTIES (" : "with dbproperties (");
             } else {
@@ -6031,7 +6113,7 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
     public boolean visit(SQLAlterTableAlterColumn x) {
         if (DbType.odps == dbType) {
             print0(ucase ? "CHANGE COLUMN" : "change column");
-        } else if (DbType.hive == dbType) {
+        } else if (DbType.hive == dbType || DbType.spark == dbType) {
             print0(ucase ? "CHANGE" : "change");
         } else {
             print0(ucase ? "ALTER COLUMN" : "alter column");
@@ -6252,7 +6334,7 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             SQLAlterTableItem item = x.getItems().get(i);
             if (i != 0) {
                 SQLAlterTableItem former = x.getItems().get(i - 1);
-                if ((this.dbType == DbType.hive || this.dbType == DbType.odps)
+                if ((this.dbType == DbType.hive || this.dbType == DbType.odps || this.dbType == DbType.spark)
                         && former instanceof SQLAlterTableAddPartition
                         && item instanceof SQLAlterTableAddPartition) {
                     // ignore comma

core/src/main/java/com/alibaba/druid/stat/TableStat.java

@@ -444,7 +444,7 @@ public class TableStat {
         private boolean having;
         private boolean join;
         private boolean primaryKey; // for ddl
-        private boolean unique; //
+        private boolean unique;
         private boolean update;
         private Map<String, Object> attributes = new HashMap<String, Object>();
         private transient String fullName;
@@ -631,7 +631,7 @@ public class TableStat {
         DropIndex(256), //
         CreateIndex(512), //
         Replace(1024),
-        DESC(2048); //
+        DESC(2048);
 
         public final int mark;
 

core/src/main/java/com/alibaba/druid/support/monitor/dao/MonitorDaoJdbcImpl.java

@@ -813,7 +813,7 @@ public class MonitorDaoJdbcImpl implements MonitorDao {
     public List<MonitorApp> listApp(String domain) throws SQLException {
         List<MonitorApp> list = new ArrayList<MonitorApp>();
 
-        String sql = "select id, domain, app from druid_app " //
+        String sql = "select id, domain, app from druid_app "
                 + " where domain = ?";
         Connection conn = null;
         PreparedStatement stmt = null;
@@ -838,7 +838,7 @@ public class MonitorDaoJdbcImpl implements MonitorDao {
     }
 
     public MonitorApp findApp(String domain, String app) throws SQLException {
-        String sql = "select id, domain, app from druid_app " //
+        String sql = "select id, domain, app from druid_app "
                 + " where domain = ? and app = ?";
         Connection conn = null;
         PreparedStatement stmt = null;
@@ -876,7 +876,7 @@ public class MonitorDaoJdbcImpl implements MonitorDao {
     public List<MonitorCluster> listCluster(String domain, String app) throws SQLException {
         List<MonitorCluster> list = new ArrayList<MonitorCluster>();
 
-        String sql = "select id, domain, app, cluster from druid_cluster " //
+        String sql = "select id, domain, app, cluster from druid_cluster "
                 + " where domain = ?";
 
         if (app != null) {
@@ -919,7 +919,7 @@ public class MonitorDaoJdbcImpl implements MonitorDao {
     }
 
     public MonitorCluster findCluster(String domain, String app, String cluster) throws SQLException {
-        String sql = "select id, domain, app, cluster from druid_cluster " //
+        String sql = "select id, domain, app, cluster from druid_cluster "
                 + " where domain = ? and app = ? and cluster = ?";
         Connection conn = null;
         PreparedStatement stmt = null;
@@ -960,19 +960,19 @@ public class MonitorDaoJdbcImpl implements MonitorDao {
                                        Date startTime, long pid) throws SQLException {
         MonitorInstance monitorInst = findInst(domain, app, cluster, host);
         if (monitorInst == null) {
-            String sql = "insert into druid_inst (domain, app, cluster, host, ip, lastActiveTime, lastPID) " //
+            String sql = "insert into druid_inst (domain, app, cluster, host, ip, lastActiveTime, lastPID) "
                     + " values (?, ?, ?, ?, ?, ?, ?)";
             JdbcUtils.execute(dataSource, sql, domain, app, cluster, host, ip, startTime, pid);
         } else {
-            String sql = "update druid_inst set ip = ?, lastActiveTime = ?, lastPID = ? " //
+            String sql = "update druid_inst set ip = ?, lastActiveTime = ?, lastPID = ? "
                     + " where domain = ? and app = ? and cluster = ? and host = ? ";
             JdbcUtils.execute(dataSource, sql, ip, startTime, pid, domain, app, cluster, host);
         }
     }
 
     public MonitorInstance findInst(String domain, String app, String cluster, String host) throws SQLException {
-        String sql = "select id, domain, app, cluster, host, ip, lastActiveTime, lastPID from druid_inst " //
-                + " where domain = ? and app = ? and cluster = ? and host = ? " //
+        String sql = "select id, domain, app, cluster, host, ip, lastActiveTime, lastPID from druid_inst "
+                + " where domain = ? and app = ? and cluster = ? and host = ? "
                 + " limit 1";
         Connection conn = null;
         PreparedStatement stmt = null;
@@ -1002,7 +1002,7 @@ public class MonitorDaoJdbcImpl implements MonitorDao {
     public List<MonitorInstance> listInst(String domain, String app, String cluster) throws SQLException {
         List<MonitorInstance> list = new ArrayList<MonitorInstance>();
 
-        String sql = "select id, domain, app, cluster, host, ip, lastActiveTime, lastPID from druid_inst " //
+        String sql = "select id, domain, app, cluster, host, ip, lastActiveTime, lastPID from druid_inst "
                 + "where domain = ?";
 
         if (app != null) {

core/src/main/java/com/alibaba/druid/util/JdbcUtils.java

@@ -550,6 +550,8 @@ public final class JdbcUtils implements JdbcConstants {
             return JdbcConstants.GBASE8S_DRIVER;
         } else if (rawUrl.startsWith("jdbc:sundb:")) {
             return JdbcConstants.SUNDB_DRIVER;
+        } else if (rawUrl.startsWith("jdbc:gaussdb:")) {
+            return "com.huawei.gaussdb.jdbc.Driver";
         } else {
             throw new SQLException("unknown jdbc driver : " + rawUrl);
         }
@@ -878,7 +880,7 @@ public final class JdbcUtils implements JdbcConstants {
         StringBuilder sql = new StringBuilder() //
                 .append("insert into ") //
                 .append(tableName) //
-                .append("("); //
+                .append("(");
 
         int nameCount = 0;
         for (String name : names) {

core/src/main/resources/META-INF/druid/parser/doris/dialect.properties

@@ -0,0 +1 @@
+quote=`

core/src/main/resources/META-INF/druid/parser/doris/keywords

@@ -0,0 +1,151 @@
+ADD
+ALL
+ALTER
+ANALYZE
+AND
+ARRAY
+AS
+ASC
+BETWEEN
+BIGINT
+BITMAP
+BOTH
+BY
+CASE
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