Hi, PR#336 is related to issue IOTDB-190.
ANTLR v4 has some advanteges over ANTLR v3: 1. ANTLRv4 uses visitor and listener mechanism，which allows the grammer definition independent from programming language (e.g. Java). So it is much easier to maintain. 2. In Antlr v3, developers explicitly defines the structure of the tree to build using operator '->'. However, Antlr v4 hides the tree structure from developers, which simplifies grammer definition and increases the code readability. 3. ANTLR v3’s LL(* ) parsing strategy is weaker than v4’s ALL(* ), so v3 sometimes relied on backtracking to properly parse input phrases. 4. ANTLR v3 cannot handle left-recursive rules, while ANTLR v4 can now handle direct left recursion. Therefore, ANTLR v4 can handle more grammer rules. 5. ANTLR v4 works faster than ANTLR v3. Now, I'm working on this issue. --------------------------------------------- Yuyuan KANG School of Software, Tsinghua University 康愈圆 清华大学 软件学院 在2019-09-01 23:58:55,Christofer Dutz<[email protected]>写道： > Hi all, > > let me give some points I know from the past: > - With Anlr4 grammars you seem to be able to express more rules > - Antlr4 parsers appear to be a lot faster than Anltr3 parsers > - Antlr4 grammars are easier to read (at least this is my impression) > - Implementing Parsers/Compilers with an Antlr4 grammar is a lot easier as > there is no longer a mixture of Antlr3 and Java code (the grammar contains > absolutely no code and all is implemented by overriding "enterXYZ" and > "exitXYZ" methods). > > So I was happy when reading that you're switching to antlr4. > > Chrus > > > Am 01.09.19, 17:38 schrieb "Xiangdong Huang" <[email protected]>: > > Hi, > > Let's discuss about PR#336.. > > 1. Which issue the PR is for. > > 2. As you (@Ring-K) upgrade the parser from antlr 3 to antlr 4, what > benefit can we get? > > Best, > ----------------------------------- > Xiangdong Huang > School of Software, Tsinghua University > > 黄向东 > 清华大学 软件学院 > >
