improved sql parser performance.

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

@@ -47,7 +47,7 @@ import com.alibaba.druid.util.StringUtils;
  * @author wenshao [szujobs@hotmail.com]
  */
 public class Lexer {
-
+    protected int          features;
     protected final String text;
     protected int          pos;
     protected int          mark;
@@ -1644,4 +1644,12 @@ public class Lexer {
     public int getPosColumn() {
         return posColumn;
     }
+
+    public void config(SQLParserFeature feature, boolean state) {
+        features = SQLParserFeature.config(features, feature, state);
+    }
+
+    public final boolean isEnabled(SQLParserFeature feature) {
+        return SQLParserFeature.isEnabled(this.features, feature);
+    }
 }

src/main/java/com/alibaba/druid/sql/parser/SQLParser.java

@@ -21,6 +21,8 @@ public class SQLParser {
 
     protected String      dbType;
 
+
+
     public SQLParser(String sql, String dbType){
         this(new Lexer(sql, null, dbType), dbType);
         this.lexer.nextToken();
@@ -316,4 +318,11 @@ public class SQLParser {
         }
     }
 
+    public void config(SQLParserFeature feature, boolean state) {
+        this.lexer.config(feature, state);
+    }
+
+    public final boolean isEnabled(SQLParserFeature feature) {
+        return lexer.isEnabled(feature);
+    }
 }

src/main/java/com/alibaba/druid/sql/parser/SQLParserFeature.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.sql.parser;
+
+public enum SQLParserFeature {
+    KeepInsertValueClauseOriginalString
+    ;
+
+    private SQLParserFeature(){
+        mask = (1 << ordinal());
+    }
+
+    public final int mask;
+
+
+    public static boolean isEnabled(int features, SQLParserFeature feature) {
+        return (features & feature.mask) != 0;
+    }
+
+    public static int config(int features, SQLParserFeature feature, boolean state) {
+        if (state) {
+            features |= feature.mask;
+        } else {
+            features &= ~feature.mask;
+        }
+
+        return features;
+    }
+
+    public static int of(SQLParserFeature[] features) {
+        if (features == null) {
+            return 0;
+        }
+
+        int value = 0;
+
+        for (SQLParserFeature feature: features) {
+            value |= feature.mask;
+        }
+
+        return value;
+    }
+}