add circuit_depth

[DhruvaSambrani]

Fixes #426

[Roger-luo]

can we have a test?

[DhruvaSambrani]

Interface question, should count_measure be a kwarg? circuit_depth(circuit, count_measure=false) vs circuit_depth(circuit, false)

[Roger-luo]

Yes I think it should be a keyword argument since it's an option, thanks!

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.06 🎉

Comparison is base (c60f6d9) 88.28% compared to head (d336a6b) 88.35%.

❗ Current head d336a6b differs from pull request most recent head 65e1549. Consider uploading reports for the commit 65e1549 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #454      +/-   ##
==========================================
+ Coverage   88.28%   88.35%   +0.06%     
==========================================
  Files          77       77              
  Lines        4824     4835      +11     
==========================================
+ Hits         4259     4272      +13     
+ Misses        565      563       -2     

Impacted Files	Coverage Δ
lib/YaoBlocks/src/blocktools.jl	89.62% <100.00%> (+1.20%)	⬆️

... and 1 file with indirect coverage changes

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[Roger-luo]

need to fix the test and make sure it passes the CI, please let me know if you have issues with that

[DhruvaSambrani]

yes sure

[GiggleLiu]

Thanks for the pull request, but I think the depth counting should be implemented in a recursive style.
Suppose I have a nested chain, the counting of depth might be wrong.

You should add a test with the following circuit:

chain(chain(put(4, 2=>X), control(4, 2, 3=>Z)))

Its depth should be 2.

Please refer the implementation of gatecount.