ANTLR VS coherence

antlr https://github.com/antlr/antlr4

Download the ANTLR jar from https://www.antlr.org/download/antlr-4.9.2-complete.jar Add the ANTLR jar to your project's classpath. Install the ANTLR Kotlin target by following the instructions at https://github.com/antlr/antlr4/blob/master/doc/targets/Kotlin.md Next, you'll need a Perl grammar file for ANTLR:

Write a context-free grammar for it, commonly written in Backus Naur Form, and use that to write a parser. There are tools named "parser generators" like antlr4 that can automatically convert a BNF grammar into a parser.

Tutorial on using it in Java: https://www.baeldung.com/java-antlr Github project itself with docs and examples: https://github.com/antlr/antlr4

Depending on how complex your expressions are, you might consider using something like antlr and writing your own parser for it. Setting up something to handle math and string operations wouldn’t be very hard and then you can control the syntax however you like. You can use a visitor and visit each node in the syntax tree and return the result of each sub-expression.

> ...than it would be to learn the exact syntax and quirks and possibly bugs of someone else's implementation...

Yup. Also, having deep knowledge of the language is required.

SQLite's grammar is neat. Creating a compatible parser would make a fun project. Here's a pretty good example: https://github.com/bkiers/sqlite-parser (Actual ANTLR 4 grammar: https://github.com/bkiers/sqlite-parser/blob/master/src/main... )

Postgres, which tries to be compliant with the latest standards, however...

SQL-2016 is a beast. Not to mention all the dialects.

I'm updating my personal (soon to be FOSS) grammar from ANTLR 3 LL(k) to ANTLR 4 ALL().

I've long had a working knowledge of SQL-92, with some SQL-1999 (eg common table expressions).

But the new structures and extensions are a bit overwhelming.

Fortunately, ANTLR project has ~dozen FOSS grammars to learn from. https://github.com/antlr/grammars-v4/tree/master/sql

They mostly mechanically translate BNFs to LL(k) with some ALL(). Meaning few take advantage of left-recursion. https://github.com/antlr/antlr4/blob/master/doc/left-recursi...

Honestly, I struggled to understand these grammars. Plus, not being conversant with the SQL-2016 was a huge impediment. Just finding a succinct corbis of test cases was a huge hurdle for me.

Fortunately, the H2 Database project is a great resource. https://github.com/h2database/h2database/tree/master/h2/src/...

Now for the exciting conclusion...

My ANTLR grammar which passes all of H2's tests looks nothing like any of the official or product specific BNFs.

Further, I found discrepancy between the product specific BNFs and their implementations.

So a lot of trial & error is required for a "real world" parser. Which would explain why the professional SQL parsing tools charge money.

I still think creating a parser for SQLite is a great project.

can be used to parse

I already posted here about a project, but I could also use help on Mantle. It's a new command framework powered by ANTLR, if that's something you're interested in.

ive been tryng to work with antlr4 and go but it seems that i cant import the runtime, it says that the antlr runtime isnt in the gopath but ive already done go get github.com/antlr/antlr4/runtime/antlr4 and i dont know what to do now, im on windows if anyone knows what to do it would be very helpful. thanks already

There are a few different tool-sets for producing Java byte code. I'm not sure which one to suggest, because back when I last needed one (end of '96), there were none, so I wrote my own. But I assume that most people use ASM or something similar.

This is one that I like a lot. Years ago (1997 timeframe) I had implemented it in a Java compiler, and a few years later in a Java library (https://github.com/oracle/coherence/blob/4e6e343e1ffd9bbfea3...) that would create an exception on the assertion failure and parse its stack trace to find the source code file name, and read it to find the text of the assertion that failed, etc. so it could build the error message ...

In Ecstasy, we built the support directly into the compiler again:

```

For the debugger (but not required by the runtime), there is an optional table that points to the ranges of ops at which names and types are bound to registers

FWIW - here's an AST for Java that directly emits Java byte code: https://github.com/oracle/coherence/tree/master/prj/coherence-core/src/main/java/com/tangosol/dev/compiler/java

It has been "experimented with" many times. Here's an example from TDE, a component-based development environment from Tangosol (now part of Oracle).

If it helps, here's a Java recursive descent parser that I wrote years ago.

If you want to see an example, here's a Context interface from a multi-language compiler framework (compiling multiple different languages to Java byte-code) that I wrote years ago.

I built an entire Java compiler in four months, from scratch, by myself, over twenty years ago. (Now owned by Oracle; still used today. Thank you, Larry.) But starting from a well written spec for a simple language like Java is orders of magnitude easier than developing a new language, runtime model, and tool-chain from scratch.

As mentioned, the various parsing methods each contribute back an AST node, so on the way down the recursion, they are parsing, and on the way back up from the recursion, they are building the tree. Here's a fairly simple recursive descent Java compiler written in Java that I wrote a few years back, in case you are looking for an example.

If you're curious how some of this can be implemented in a Java compiler, I wrote one years ago. For example, checking that the left side is an l-value: