improved postgresql sql parser support. support SIMILAR TO Operator. issue #1391

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBinaryOperator.java

@@ -58,6 +58,7 @@ public enum SQLBinaryOperator {
     ILike("ILIKE", 110),
     NotILike("NOT ILIKE", 110),
     AT_AT("@@", 110), // postgresql textsearch
+    SIMILAR_TO("SIMILAR TO", 110),
     
     RLike("RLIKE", 110),
     NotRLike("NOT RLIKE", 110),

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

@@ -226,6 +226,10 @@ public class Lexer {
         return token;
     }
 
+    public final String getDbType() {
+        return this.dbType;
+    }
+
     public String info() {
         return this.token + " " + this.stringVal();
     }

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

@@ -1492,6 +1492,16 @@ public class SQLExprParser extends SQLParser {
             }
         } else if (lexer.token() == Token.IN) {
             expr = inRest(expr);
+        } else if (JdbcConstants.POSTGRESQL.equals(lexer.dbType)
+                && identifierEquals("SIMILAR")) {
+            lexer.nextToken();
+            accept(Token.TO);
+
+            rightExp = equality();
+
+            rightExp = relationalRest(rightExp);
+
+            expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.SIMILAR_TO, rightExp, getDbType());
         }
 
         return expr;