Fix DOMAIN conflict on MacOS

[majetideepak]

On MacOS, I see the following error when building.

././target/generated-sources/javacc/SqlParserConstants.h:142:12: error: expected unqualified-id
const  int DOMAIN = 64;
           ^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/math.h:734:17: note: expanded from macro 'DOMAIN'
#define DOMAIN  

[kaikalur]

We should actually see why math.h is even included and clean that up.

[kaikalur]

Also we use '_' prefixx for conflicts (like _EOF). So let's follow that practice if it is really needed. But I would like to remove useless includes and get rid of this error

[majetideepak]

@kaikalur I looked at the clang verbose output and the math library is not being included explicitly. It's probably part of the clang runtime.

[kaikalur]

No runtime should not matter. I think the issue is in main.cc where we include file.h

[majetideepak]

@kaikalur removing fstream fixed it. I will look for an alternative.

[majetideepak]

@kaikalur I replaced ifstream with C-style file reading. Let me know if you have a better approach.

[kaikalur]

This code was a couple of weekend hacking back in 2020 lol so it's quality shows. Grammar/AST part should be decent though.

So feel free to fixup the code the way you see fit.

[kaikalur]

I just added a makefile that separates the main from the parser library. If you can setup a buck build or cmake that will be great :)

[majetideepak]

@kaikalur I will be adding some CMake build files later. The background is that we want to use the parser here to parse expressions in Velox tests. See the discussion here: facebookincubator/velox#5589
The APIs we need to implement are https://github.com/facebookincubator/velox/blob/main/velox/duckdb/conversion/DuckParser.h
Would you happen to have any feedback for us? Thanks.

[majetideepak]

I invoked value_expression_primary() on cast(switch(gt(c0, c1), c1, c0) as double) and was able to get the parse tree.
I need to investigate other APIs.

[kaikalur]

@kaikalur I will be adding some CMake build files later. The background is that we want to use the parser here to parse expressions in Velox tests. See the discussion here: facebookincubator/velox#5589 The APIs we need to implement are https://github.com/facebookincubator/velox/blob/main/velox/duckdb/conversion/DuckParser.h Would you happen to have any feedback for us? Thanks.

We can add methods like ParseExpression to ParserClient class that I just started working on:

https://fburl.com/kwjuum7p

[majetideepak]

We can add methods like ParseExpression to ParserClient class that I just started working on:

@kaikalur Sounds good! I am not a Meta employee. So I cannot access your link. But I think we are aligned on the goal here.
I will explore the parser a bit more for Velox's needs and update it here.
I will then work on the CMake support so that we can install the parser as a library.