I'm running out my door now, so don't have much time...but just wanna say this is GREAT WORK ;)
/max
Joshua Davis wrote:
Hibernate programmers,
I've made some progress with the HQL parser, so here's an update:
Design decisions:
1) Use ANTLR to generate the parser. It has a compatible Open Source licence, and adds only one new library dependency.
2) Use a three phase design: parse/analyze/generate code - This is a very typical modular compiler design. The parse phase is implemented as a stream parser, the analysis phase is implemented as a tree parser (tree transform, actually), and the code generation phase is a tree parser that produces an SQL stream.
3) Use the ANTLR generated parsers as base classes, implementing the main semantic / syntax analysis functions in derived classes. This keeps the grammar files smaller, and alows me to use my favorite Java IDE to write the analysis code.
So, what's been done so far?
* An HQL grammar / parser which sucessfully parses most of the examples in the Hibernate HQL doco. A few additional features have been added, as well as a unit test that exercises this phase.
* An HQL AST analyzer, which converts the HQL AST into an intermediate, SQL (ish) AST. This is implemented as a tree parser which normalizes the HQL AST and binds the HQL AST elements to the appropriate Hibernate mapping API objects (e.g. Queryable, etc.).
* A very simplistic SQL generator, which walks the intermediate tree and produces an SQL stream. This is primarly for testing, although it might come in handy later on when integrating all this into Hibernate.
* Some initial 'implied join' examples.
What's next?
* Get implied joins (and 'fake' AST generation to work).
* Utilize more of the existing Hibernate API for mappings.
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