code generation for rubi - continue #14988

[Shekharrajak]

References to other Issues or PRs

Continuation of #14988

Brief description of what is fixed or changed

Trying out codegen writtein in #14988 with new MatchPy and modifying it accordingly.

Other comments

# Name                    Version                   Build  Channel
matchpy                   0.5.1                    pypi_0    pypi

Release Notes

• integrals.rubi
  • Code Generation for Rubi

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#### References to other Issues or PRs

Continuation of #14988

#### Brief description of what is fixed or changed

Trying out codegen writtein in #14988 with new MatchPy and modifying it accordingly.

#### Other comments

```
# Name                    Version                   Build  Channel
matchpy                   0.5.1                    pypi_0    pypi

```


#### Release Notes

<!-- Write the release notes for this release below. See
https://github.com/sympy/sympy/wiki/Writing-Release-Notes for more information
on how to write release notes. The bot will check your release notes
automatically to see if they are formatted correctly. -->

<!-- BEGIN RELEASE NOTES -->

- integrals.rubi
     * Code Generation for Rubi

<!-- END RELEASE NOTES -->

[Shekharrajak]

@Upabjojr , I created this PR to check for latest matchpy version. I tried to cherry-pick Ashish's commit but when I updated with latest master branch, I messed with conflicts. So here I am directly using the codegen file in latest master branch of SymPy.

[Shekharrajak]

Here is the example I tried :

>>> from sympy.integrals.rubi import codegen
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/shekharrajak/Documents/sympy/sympy/sympy/integrals/rubi/codegen.py", line 57, in <module>
    generator = RubiCodeGenerator(rubi)
  File "/home/anaconda3/envs/sympy-dev/lib/python3.7/site-packages/matchpy/matching/code_generation.py", line 28, in __init__
    self._patterns = set(range(len(matcher.patterns)))
AttributeError: 'ManyToOneReplacer' object has no attribute 'patterns'

[Upabjojr]

The code generator works on the ManyToOneMatcher object. You should extract it from the ManyToOneReplacer.

[Upabjojr]

I have extracted the ManyToOneMatcher. There are still problems related to the constraints and lambdas, they should be fixed.

[Upabjojr]

I have disabled most of the rules. It is now possible to do experiments in reasonable time.

[Upabjojr]

OK, I think I see what the problems are:

• the replacement functions are defined as local functions inside the functions loading the rules (e.g. replacement rule number 1). The rules are generated, so it's a problem with the generator.
• the constraint printer is unable to handle ordinary function. The function constraint_repr in RubiCodeGenerator should be modified accordingly. I believe you should start by returning return constraint.constraint.__name__, False or something similar.

[Upabjojr]

In particular, the first part requires to redesign the code generator, which may be tedious.

[Upabjojr]

If you have Wolfram Mathematica installed, try to follow: https://github.com/sympy/sympy/wiki/Rubi-parsing-guide

[Upabjojr]

Here we go again:
https://github.com/Upabjojr/RUBI-4.10-parsed

[Upabjojr]

I've just noticed a mistake. Correcting wrong documentation #17101