improved sql parser.

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

@@ -60,7 +60,7 @@ public class Lexer {
     protected long         hash;
 
     protected int            commentCount = 0;
-    protected List<String>   comments     = new ArrayList<String>(2);
+    protected List<String>   comments     = null;
     protected boolean        skipComment  = true;
     private SavePoint        savePoint    = null;
 

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

@@ -913,7 +913,7 @@ public class SQLExprParser extends SQLParser {
         SQLExpr owner = null;
         String trimOption = null;
 
-        long hash_lower;
+        long hash_lower = 0L;
         if (expr instanceof SQLIdentifierExpr) {
             SQLIdentifierExpr identifierExpr = (SQLIdentifierExpr) expr;
             methodName = identifierExpr.getName();
@@ -964,7 +964,7 @@ public class SQLExprParser extends SQLParser {
             return aggregateExpr;
         }
 
-        methodInvokeExpr = new SQLMethodInvokeExpr(methodName);
+        methodInvokeExpr = new SQLMethodInvokeExpr(methodName, hash_lower);
         if (owner != null) {
             methodInvokeExpr.setOwner(owner);
         }

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

@@ -565,10 +565,16 @@ public class SQLSelectParser extends SQLParser {
 
     protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) {
         if ((tableSource.getAlias() == null) || (tableSource.getAlias().length() == 0)) {
-            if (lexer.token != Token.LEFT && lexer.token != Token.RIGHT && lexer.token != Token.FULL
-                    && (!lexer.identifierEquals(FnvHash.Constants.STRAIGHT_JOIN))
-                    && (!lexer.identifierEquals(FnvHash.Constants.CROSS))
-                    && lexer.token != Token.OUTER) {
+            Token token = lexer.token;
+            long hash;
+            if (token != Token.LEFT
+                    && token != Token.RIGHT
+                    && token != Token.FULL
+                    && token != Token.OUTER
+                    && !(token == Token.IDENTIFIER
+                        && ((hash = lexer.hash_lower()) == FnvHash.Constants.STRAIGHT_JOIN
+                            || hash == FnvHash.Constants.CROSS)))
+            {
                 String alias = tableAlias();
                 if (alias != null) {
                     tableSource.setAlias(alias);

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

@@ -15,10 +15,14 @@
  */
 package com.alibaba.druid.sql.parser;
 
+import java.nio.charset.Charset;
+
 /**
  * @author wenshao[szujobs@hotmail.com]
  */
 public class SymbolTable {
+    private static final Charset UTF8 = Charset.forName("UTF-8");
+
     public static SymbolTable global = new SymbolTable(8192);
 
     private final Entry[] entries;
@@ -29,15 +33,12 @@ public class SymbolTable {
         this.entries = new Entry[tableSize];
     }
 
-
-
     public String addSymbol(String buffer, int offset, int len, long hash) {
         final int bucket = ((int) hash) & indexMask;
 
         Entry entry = entries[bucket];
         if (entry != null) {
-            if (hash == entry.hash //
-                    && len == entry.len) {
+            if (hash == entry.hash) {
                 return entry.value;
             }
 
@@ -52,12 +53,64 @@ public class SymbolTable {
         return str;
     }
 
+    public String addSymbol(byte[] buffer, int offset, int len, long hash) {
+        final int bucket = ((int) hash) & indexMask;
+
+        Entry entry = entries[bucket];
+        if (entry != null) {
+            if (hash == entry.hash) {
+                return entry.value;
+            }
+
+            String str = subString(buffer, offset, len);
+
+            return str;
+        }
+
+        String str = subString(buffer, offset, len);
+        entry = new Entry(hash, len, str);
+        entries[bucket] = entry;
+        return str;
+    }
+
+    public String addSymbol(String symbol, long hash) {
+        final int bucket = ((int) hash) & indexMask;
+
+        Entry entry = entries[bucket];
+        if (entry != null) {
+            if (hash == entry.hash) {
+                return entry.value;
+            }
+
+            return symbol;
+        }
+
+        entry = new Entry(hash, symbol.length(), symbol);
+        entries[bucket] = entry;
+        return symbol;
+    }
+
+    public String findSymbol(long hash) {
+        final int bucket = ((int) hash) & indexMask;
+        Entry entry = entries[bucket];
+        if (entry != null && entry.hash == hash) {
+            return entry.value;
+        }
+        return null;
+    }
+
     private static String subString(String src, int offset, int len) {
         char[] chars = new char[len];
         src.getChars(offset, offset + len, chars, 0);
         return new String(chars);
     }
 
+    private static String subString(byte[] bytes, int from, int len) {
+        byte[] strBytes = new byte[len];
+        System.arraycopy(bytes, from, strBytes, 0, len);
+        return new String(strBytes, UTF8);
+    }
+
     private static class Entry {
         public final long hash;
         public final int len;