tristaZero commented on issue #3914: Optimization for Sharing Parser with Antlr Visitor URL: https://github.com/apache/incubator-shardingsphere/issues/3914#issuecomment-574108748 ## Here is instruction ### Tasks: 1. Add rule visitors in `MySQLVisitor.java` based on g4 files[1]. 2. Check whether rule name in g4 files is appropriate or not. 3. Add parsed integrated test for your **new main rule visitor**. ### Task detail: 1. Add rule visitors 1.1 Since `MySQLVisitor.java` extends `MySQLStatementBaseVisitor<ASTNode>.java`, you should overwrite `visitRuleName(ctx)` from `MySQLStatementBaseVisitor<ASTNode>` referring to rules in g4 files. 1.2 When adding `visitRuleName(ctx)`, you should put it below the corresponding note generally named `xxx.g4` and keep its order same with where it is in `xxx.g4` file. 1.3 What we need after parsing is those classes implement `SQLStatemnt` interface, so you should parse all necessary rules (add necessary rule visitors) making up `the main rules` in `MySQLStatement.g4`, and then fill necessary `segments` to `xxxSQLStatemnt`. 2.Check rule name 2.1 If we do not care one rule (do not add visitor for it), its name should end up with `_` in g4 file. For instance, we do not add visitor for `IDENTIFIER_` in `baseRule.g4`. 2.2 Otherwise this rule name should not contain `_` in the end. 2.3 If existing rule name does not accord with the above rules, please fix it. 3. Add parsed integrated test When you successfully add `one main rule visitor`, adding parsed integrated test for it is necessary. 3.1 Copy sql case you need from `./incubator-shardingsphere/sharding-sql-test/src/main/resources/sql/sharding/` to `./incubator-shardingsphere/sharding-sql-test/src/main/resources/sql/visitor/` (`Please note to keep the same directory`). 3.2 Copy the corresponding sql parsed result from `./incubator-shardingsphere/shardingsphere-sql-parser/shardingsphere-sql-parser-test/src/test/resources/sharding/` to ` ./incubator-shardingsphere/shardingsphere-sql-parser/shardingsphere-sql-parser-test/src/test/resources/visitor/` (`Please note to keep the same directory`). 3.3 Run `org.apache.shardingsphere.sql.parser.integrate.engine.visitor.VisitorParameterizedParsingTest`. 3.4 If there is no sql case you need in `./incubator-shardingsphere/sharding-sql-test/src/main/resources/sql/sharding/`, please record it to this issue[2]. P.S, my suggestion is to easily test its parsed result previously. ### Examples 1. Current functions in `org.apache.shardingsphere.sql.parser.MySQLVisitor` could provide examples for you. 2. You could learn more the parsed integrated test from test entrance `org.apache.shardingsphere.sql.parser.integrate.engine.visitor.VisitorParameterizedParsingTest`. ### Notice 1. This guideline applys to `OracleVisitor`, `PostrgreSQLVisitor`, `SQLServerVisitor` and `SQL92Visitor` as well. [1] DALStatement.g4, DCLStatement.g4, DDLStatement.g4, DMLStatement.g4, TCLStatement.g4 and StoreProcedure.g4 [2] https://github.com/apache/incubator-shardingsphere/issues/3967
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