refactor sqlserver offset

sharding-jdbc-core/src/main/java/com/dangdang/ddframe/rdb/sharding/parsing/parser/dialect/sqlserver/SQLServerOffsetParser.java

+/*
+ * Copyright 1999-2015 dangdang.com.
+ * <p>
+ * 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.
+ * </p>
+ */
+
+package com.dangdang.ddframe.rdb.sharding.parsing.parser.dialect.sqlserver;
+
+import com.dangdang.ddframe.rdb.sharding.parsing.lexer.LexerEngine;
+import com.dangdang.ddframe.rdb.sharding.parsing.lexer.dialect.sqlserver.SQLServerKeyword;
+import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.DefaultKeyword;
+import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.Literals;
+import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.Symbol;
+import com.dangdang.ddframe.rdb.sharding.parsing.parser.context.limit.Limit;
+import com.dangdang.ddframe.rdb.sharding.parsing.parser.context.limit.LimitValue;
+import com.dangdang.ddframe.rdb.sharding.parsing.parser.exception.SQLParsingException;
+import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.SQLParser;
+import com.dangdang.ddframe.rdb.sharding.parsing.parser.statement.dql.select.SelectStatement;
+
+/**
+ * SQLServer Top解析器.
+ *
+ * @author zhangliang
+ */
+public final class SQLServerOffsetParser implements SQLParser {
+    
+    private final LexerEngine lexerEngine;
+    
+    public SQLServerOffsetParser(final LexerEngine lexerEngine) {
+        this.lexerEngine = lexerEngine;
+    }
+    
+    /**
+     * 解析Offset.
+     * 
+     * @param selectStatement Select SQL语句对象
+     */
+    public void parse(final SelectStatement selectStatement) {
+        if (!lexerEngine.skipIfEqual(SQLServerKeyword.OFFSET)) {
+            return;
+        }
+        int offsetValue = -1;
+        int offsetIndex = -1;
+        if (lexerEngine.equalAny(Literals.INT)) {
+            offsetValue = Integer.parseInt(lexerEngine.getCurrentToken().getLiterals());
+        } else if (lexerEngine.equalAny(Symbol.QUESTION)) {
+            offsetIndex = selectStatement.getParametersIndex();
+            selectStatement.increaseParametersIndex();
+        } else {
+            throw new SQLParsingException(lexerEngine);
+        }
+        lexerEngine.nextToken();
+        Limit limit = new Limit(true);
+        if (lexerEngine.skipIfEqual(DefaultKeyword.FETCH)) {
+            lexerEngine.nextToken();
+            int rowCountValue = -1;
+            int rowCountIndex = -1;
+            lexerEngine.nextToken();
+            if (lexerEngine.equalAny(Literals.INT)) {
+                rowCountValue = Integer.parseInt(lexerEngine.getCurrentToken().getLiterals());
+            } else if (lexerEngine.equalAny(Symbol.QUESTION)) {
+                rowCountIndex = selectStatement.getParametersIndex();
+                selectStatement.increaseParametersIndex();
+            } else {
+                throw new SQLParsingException(lexerEngine);
+            }
+            lexerEngine.nextToken();
+            lexerEngine.nextToken();
+            limit.setRowCount(new LimitValue(rowCountValue, rowCountIndex));
+            limit.setOffset(new LimitValue(offsetValue, offsetIndex));
+        } else {
+            limit.setOffset(new LimitValue(offsetValue, offsetIndex));
+        }
+        selectStatement.setLimit(limit);
+    }
+}

sharding-jdbc-core/src/main/java/com/dangdang/ddframe/rdb/sharding/parsing/parser/dialect/sqlserver/SQLServerSelectParser.java

@@ -21,12 +21,8 @@ import com.dangdang.ddframe.rdb.sharding.api.rule.ShardingRule;
 import com.dangdang.ddframe.rdb.sharding.parsing.lexer.LexerEngine;
 import com.dangdang.ddframe.rdb.sharding.parsing.lexer.dialect.sqlserver.SQLServerKeyword;
 import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.DefaultKeyword;
-import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.Literals;
 import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.Symbol;
-import com.dangdang.ddframe.rdb.sharding.parsing.parser.context.limit.Limit;
-import com.dangdang.ddframe.rdb.sharding.parsing.parser.context.limit.LimitValue;
 import com.dangdang.ddframe.rdb.sharding.parsing.parser.dialect.mysql.MySQLOrderBySQLParser;
-import com.dangdang.ddframe.rdb.sharding.parsing.parser.exception.SQLParsingException;
 import com.dangdang.ddframe.rdb.sharding.parsing.parser.exception.SQLParsingUnsupportedException;
 import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.AbstractOrderBySQLParser;
 import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.DistinctSQLParser;
@@ -55,6 +51,8 @@ public final class SQLServerSelectParser extends AbstractSelectParser {
     
     private final AbstractOrderBySQLParser orderBySQLParser;
     
+    private final SQLServerOffsetParser sqlServerOffsetParser;
+    
     public SQLServerSelectParser(final ShardingRule shardingRule, final LexerEngine lexerEngine) {
         super(shardingRule, lexerEngine, new SQLServerWhereSQLParser(lexerEngine));
         distinctSQLParser = new DistinctSQLParser(lexerEngine);
@@ -63,6 +61,7 @@ public final class SQLServerSelectParser extends AbstractSelectParser {
         groupBySQLParser = new GroupBySQLParser(lexerEngine);
         havingSQLParser = new HavingSQLParser(lexerEngine);
         orderBySQLParser = new MySQLOrderBySQLParser(lexerEngine);
+        sqlServerOffsetParser = new SQLServerOffsetParser(lexerEngine);
     }
     
     @Override
@@ -75,49 +74,10 @@ public final class SQLServerSelectParser extends AbstractSelectParser {
         groupBySQLParser.parse(selectStatement);
         havingSQLParser.parse();
         orderBySQLParser.parse(selectStatement);
-        parseOffset(selectStatement);
+        sqlServerOffsetParser.parse(selectStatement);
         parseFor();
     }
     
-    private void parseOffset(final SelectStatement selectStatement) {
-        if (!getLexerEngine().skipIfEqual(SQLServerKeyword.OFFSET)) {
-            return;
-        }
-        int offsetValue = -1;
-        int offsetIndex = -1;
-        if (getLexerEngine().equalAny(Literals.INT)) {
-            offsetValue = Integer.parseInt(getLexerEngine().getCurrentToken().getLiterals());
-        } else if (getLexerEngine().equalAny(Symbol.QUESTION)) {
-            offsetIndex = getParametersIndex();
-            selectStatement.increaseParametersIndex();
-        } else {
-            throw new SQLParsingException(getLexerEngine());
-        }
-        getLexerEngine().nextToken();
-        Limit limit = new Limit(true);
-        if (getLexerEngine().skipIfEqual(DefaultKeyword.FETCH)) {
-            getLexerEngine().nextToken();
-            int rowCountValue = -1;
-            int rowCountIndex = -1;
-            getLexerEngine().nextToken();
-            if (getLexerEngine().equalAny(Literals.INT)) {
-                rowCountValue = Integer.parseInt(getLexerEngine().getCurrentToken().getLiterals());
-            } else if (getLexerEngine().equalAny(Symbol.QUESTION)) {
-                rowCountIndex = getParametersIndex();
-                selectStatement.increaseParametersIndex();
-            } else {
-                throw new SQLParsingException(getLexerEngine());
-            }
-            getLexerEngine().nextToken();
-            getLexerEngine().nextToken();
-            limit.setRowCount(new LimitValue(rowCountValue, rowCountIndex));
-            limit.setOffset(new LimitValue(offsetValue, offsetIndex));
-        } else {
-            limit.setOffset(new LimitValue(offsetValue, offsetIndex));
-        }
-        selectStatement.setLimit(limit);
-    }
-    
     private void parseFor() {
         if (!getLexerEngine().skipIfEqual(DefaultKeyword.FOR)) {
             return;