Had a deeper look, I can answer my own questions now. 1. Adding a list of SqlFunction to a parser? No need. The SqlParser will parse unknown symbols that look like function calls as SqlCall nodes with SqlKind "OTHER_FUNCTION" and SqlFunctionCategory "USER_DEFINED_FUNCTION".
Note: I was actually getting confused by how functions identifiers are escaped in the toString method. For instance: select EXP(col), myMacro(col) from ... will be parsed then returned as String as EXP(`col`), `myMacro`(`col`) from ... Not sure to understand why the EXP is not escaped, but I was able to play with the toSqlString method to get what I want. 2. Parse a SQL query, traverse the tree recursively, replace some nodes, then get back a Sql string ? Yes, it's a good use case for Calcite. A good inspiration was the Hoist <https://calcite.apache.org/javadocAggregate/org/apache/calcite/tools/Hoist.html> class. It replaces constants in q SQL string. I implemented something similar that replaces my "USER_DEFINED_FUNCTION" macros. It works like a charm. Have a nice day. On Wed, Nov 3, 2021 at 9:53 PM Cyril Catheu <[email protected]> wrote: > Hey, > > I'm working on a product that executes arbitrary SQL on a "data source". > A data source implements a SQL language, for instance, it can be MySQL, > Pinot, BigQuery, etc... > I'd like to introduce a macro language on top of the SQL. > Very similar to what is done in grafana: > https://grafana.com/docs/grafana/latest/datasources/mysql/#macros > These macros would be resolved before the SQL is executed on the data > source. > > A macro looks like a function but is a string replacement, for instance: > __timeFilter(timeColumn, start, end) --> timeColumn>=start and > timeColumn<end > > Grafana uses regex replacements, but I'm considering parsing the SQL with > Calcite to apply the macros safely and manage nested macros/functions. > > --> Is this a good use case for Calcite? What seemed interesting to me is > that Calcite has all those SqlDialect implementations. > > I had this flow in mind: > 1. get the SqlDialect of my datasource > *2.* add to this dialect my custom macros (add to an SqlFunction list? ) > 3. parse > 4. replace > 5. rebuild > > I'm wondering if 2. is possible? I'm not sure to understand how I could > add a list of SqlFunction to a dialect, or build a new dialect from an > existing one dynamically. > > If you've taken the time to read this message, thanks a lot! > Have a nice day. > > -- > [image: Startree] <https://www.startree.ai/> > > Cyril de Catheu > > Software Engineer, StarTree > > [email protected] | +33 684-829-908 > > [image: Linkedin] <https://www.linkedin.com/in/cyril-de-catheu/>[image: > Twitter] <https://twitter.com/deCatheu> >
