GSoC 2023: Yige Huang Week 3

[squarege]

Changes proposed in this pull request:

• Reverting the modification of docqueries and pgtap.
• Creating new files for new function.
• Adding new signatures.
• Simplifying header file.
• Fixing lincenses.

@pgRouting/admins

[squarege]

Here is the function I wrote to check the driving side. I am inexperienced in error checking, can you please give me some advice？ @krashish8

[krashish8]

I'd suggest that if you are raising some error, why not raise it early, i.e. in the SQL code itself? You can look at PLPGSQL documentation on how to do so - a very small example might be:
https://github.com/pgRouting/pgrouting/blob/6c47f688c7ec219b5251b0020db4bc439ed2421a/sql/breadthFirstSearch/breadthFirstSearch.sql#L54-L57

Once the code of execution goes to C/C++, you can just set the default values of driving distance, assuming that the error checking is done by the SQL code. Inside this estimate_drivingSide_dd function, you can also try to use C++ functions if possible, such as std::tolower, std::string.find(), etc.

I added a comment in that issue - #300 (comment)
Have we finalized whether we are changing the default value of driving side to 'r', or will it be the same as before ('b'), or do we still need to check on that?

[squarege]

Last meeting, vicky says that I can make the check on SQL level or C/C++ level. But since I don't know how to check on the SQL level, I chose the latter. Thank you for your guidance and I will follow the PLPGSQL documentation and also the given example, trying to raise error on SQL level.

Actually, there will not any default value for driving side because I'm creating a new function that the driving side is compulsory rather than optional. User must give a proper value for driving side or the function will not work. Since there are some restrictions, like "Both" is only valid on undirected graphs (If b is given meanwhile graph is directed, I consider it should raise error because you cannot drive on both side in a directed graph), I think the check is needed.

Again, thanks for your guidance！