improve sqlwall and parser

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

@@ -110,6 +110,8 @@ public class MySqlLexer extends Lexer {
         if (commentHandler != null && commentHandler.handle(lastToken, stringVal)) {
             return;
         }
+        
+        endOfComment = isEOF();
 
         if (!isAllowComment() && (isEOF() || !isSafeComment(stringVal))) {
             throw new NotAllowCommentException();
@@ -448,6 +450,8 @@ public class MySqlLexer extends Lexer {
                 return;
             }
 
+            endOfComment = isEOF();
+            
             if (!isHint && !isAllowComment() && (isEOF() || !isSafeComment(stringVal))) {
                 throw new NotAllowCommentException();
             }
@@ -489,6 +493,8 @@ public class MySqlLexer extends Lexer {
                 return;
             }
 
+            endOfComment = isEOF();
+            
             if (!isAllowComment() && (isEOF() || !isSafeComment(stringVal))) {
                 throw new NotAllowCommentException();
             }

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

@@ -136,6 +136,7 @@ public class OdpsLexer extends Lexer {
             stringVal = subString(mark + 1, bufPos);
             token = Token.LINE_COMMENT;
             hasComment = true;
+            endOfComment = isEOF();
             return;
         }
     }

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

@@ -274,6 +274,7 @@ public class OracleLexer extends Lexer {
             stringVal = subString(mark + 1, bufPos);
             token = Token.LINE_COMMENT;
             hasComment = true;
+            endOfComment = isEOF();
             return;
         }
     }

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

@@ -149,6 +149,7 @@ public class SQLServerLexer extends Lexer {
             stringVal = subString(mark + 1, bufPos);
             token = Token.LINE_COMMENT;
             hasComment = true;
+            endOfComment = isEOF();
             return;
         }
     }

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

@@ -64,13 +64,15 @@ public class Lexer {
     /*
      * anti sql injection
      */
-    private boolean        allowComment = true;
+    private boolean          allowComment = true;
 
-    private int            varIndex     = -1;
+    private int              varIndex     = -1;
 
     protected CommentHandler commentHandler;
-    
-    protected boolean        hasComment = false;
+
+    protected boolean        hasComment   = false;
+
+    protected boolean        endOfComment = false;
 
     public Lexer(String input){
         this(input, true);
@@ -1058,4 +1060,9 @@ public class Lexer {
         pos = text.length();
         this.token = Token.EOF;
     }
+
+    public boolean isEndOfComment() {
+        return endOfComment;
+    }
+
 }

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

@@ -169,6 +169,9 @@ public class SQLParser {
         } else if (lexer.token() == Token.USER) {
             alias = lexer.stringVal();
             lexer.nextToken();
+        } else if (lexer.token() == Token.END) {
+            alias = lexer.stringVal();
+            lexer.nextToken();
         } 
 
         switch (lexer.token()) {

src/main/java/com/alibaba/druid/wall/WallProvider.java

@@ -604,6 +604,7 @@ public abstract class WallProvider {
         final List<Violation> violations = new ArrayList<Violation>();
         List<SQLStatement> statementList = new ArrayList<SQLStatement>();
         boolean syntaxError = false;
+        boolean endOfComment = false;
         try {
             SQLStatementParser parser = createParser(sql);
             parser.getLexer().setCommentHandler(WallCommentHandler.instance);
@@ -619,10 +620,11 @@ public abstract class WallProvider {
             parser.parseStatementList(statementList);
 
             final Token lastToken = parser.getLexer().token();
-            if (lastToken != Token.EOF) {
+            if (lastToken != Token.EOF && config.isStrictSyntaxCheck()) {
                 violations.add(new IllegalSQLObjectViolation(ErrorCode.SYNTAX_ERROR, "not terminal sql, token "
                                                                                      + lastToken, sql));
             }
+            endOfComment = parser.getLexer().isEndOfComment();
         } catch (NotAllowCommentException e) {
             violations.add(new IllegalSQLObjectViolation(ErrorCode.COMMENT_STATEMENT_NOT_ALLOW, "comment not allow", sql));
             incrementCommentDeniedCount();
@@ -643,6 +645,9 @@ public abstract class WallProvider {
         }
 
         WallVisitor visitor = createWallVisitor();
+        if (!endOfComment) {
+            visitor.getConfig().setSelectUnionCheck(false);
+        }
 
         if (statementList.size() > 0) {
             boolean lastIsHint = false;