improve sql parser for db2

src/main/java/com/alibaba/druid/sql/dialect/db2/ast/stmt/DB2SelectQueryBlock.java

@@ -27,6 +27,10 @@ public class DB2SelectQueryBlock extends SQLSelectQueryBlock implements DB2Objec
 
     private Isolation isolation;
 
+    private boolean   forReadOnly;
+
+    private SQLExpr   optimizeFor;
+
     public SQLExpr getFirst() {
         return first;
     }
@@ -65,6 +69,22 @@ public class DB2SelectQueryBlock extends SQLSelectQueryBlock implements DB2Objec
         this.isolation = isolation;
     }
 
+    public boolean isForReadOnly() {
+        return forReadOnly;
+    }
+
+    public void setForReadOnly(boolean forReadOnly) {
+        this.forReadOnly = forReadOnly;
+    }
+
+    public SQLExpr getOptimizeFor() {
+        return optimizeFor;
+    }
+
+    public void setOptimizeFor(SQLExpr optimizeFor) {
+        this.optimizeFor = optimizeFor;
+    }
+
     public static enum Isolation {
         RR, RS, CS, UR
     }

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

@@ -35,6 +35,7 @@ public class DB2Lexer extends Lexer {
         map.put("FETCH", Token.FETCH);
         map.put("FIRST", Token.FIRST);
         map.put("ONLY", Token.ONLY);
+        map.put("OPTIMIZE", Token.OPTIMIZE);
         
         DEFAULT_DB2_KEYWORDS = new Keywords(map);
     }

src/main/java/com/alibaba/druid/sql/dialect/db2/parser/DB2SelectParser.java

@@ -77,31 +77,57 @@ public class DB2SelectParser extends SQLSelectParser {
 
         parseGroupBy(queryBlock);
 
-        if (lexer.token() == Token.FETCH) {
-            lexer.nextToken();
-            accept(Token.FIRST);
-            SQLExpr first = this.exprParser.primary();
-            queryBlock.setFirst(first);
-            if (identifierEquals("ROW") || identifierEquals("ROWS")) {
-                lexer.nextToken();
-            }
-            accept(Token.ONLY);
-        }
 
-        if (lexer.token() == Token.WITH) {
-            lexer.nextToken();
-            if (identifierEquals("RR")) {
-                queryBlock.setIsolation(Isolation.RR);
-            } else if (identifierEquals("RS")) {
-                queryBlock.setIsolation(Isolation.RS);
-            } else if (identifierEquals("CS")) {
-                queryBlock.setIsolation(Isolation.CS);
-            } else if (identifierEquals("UR")) {
-                queryBlock.setIsolation(Isolation.UR);
-            } else {
-                throw new ParserException("TODO");
+        for (;;) {
+            if (lexer.token() == Token.FETCH) {
+                lexer.nextToken();
+                accept(Token.FIRST);
+                SQLExpr first = this.exprParser.primary();
+                queryBlock.setFirst(first);
+                if (identifierEquals("ROW") || identifierEquals("ROWS")) {
+                    lexer.nextToken();
+                }
+                accept(Token.ONLY);
+                continue;
             }
-            lexer.nextToken();
+            
+            if (lexer.token() == Token.WITH) {
+                lexer.nextToken();
+                if (identifierEquals("RR")) {
+                    queryBlock.setIsolation(Isolation.RR);
+                } else if (identifierEquals("RS")) {
+                    queryBlock.setIsolation(Isolation.RS);
+                } else if (identifierEquals("CS")) {
+                    queryBlock.setIsolation(Isolation.CS);
+                } else if (identifierEquals("UR")) {
+                    queryBlock.setIsolation(Isolation.UR);
+                } else {
+                    throw new ParserException("TODO");
+                }
+                lexer.nextToken();
+                continue;
+            }
+            
+            if (lexer.token() == Token.FOR) {
+                lexer.nextToken();
+                acceptIdentifier("READ");
+                accept(Token.ONLY);
+                queryBlock.setForReadOnly(true);
+            }
+            
+            if (lexer.token() == Token.OPTIMIZE) {
+                lexer.nextToken();
+                accept(Token.FOR);
+                
+                queryBlock.setOptimizeFor(this.expr());
+                if (identifierEquals("ROW")) {
+                    lexer.nextToken();
+                } else {
+                    acceptIdentifier("ROWS");
+                }
+            }
+            
+            break;
         }
 
         return queryRest(queryBlock);

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

@@ -36,12 +36,23 @@ public class DB2OutputVisitor extends SQLASTOutputVisitor implements DB2ASTVisit
             print(" ROWS ONLY");
         }
         
+        if (x.isForReadOnly()) {
+            println();
+            print("FOR READ ONLY");
+        }
+        
         if (x.getIsolation() != null) {
             println();
             print("WITH ");
             print(x.getIsolation().name());
         }
         
+        if (x.getOptimizeFor() != null) {
+            println();
+            print("OPTIMIZE FOR ");
+            x.getOptimizeFor().accept(this);
+        }
+        
         return false;
     }