feat (HIS): add HIS metrics checker

[AfonsoSantos96]

HIS Checker

This PR introduces a new feature on the ci, the HIS metrics checker.
The following table lists the HIS metrics to be implemented, indicating the threshold for each metric (in the Description column).
The PR column contains the link to the PR where the metric check was implemented.

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Edited by @danielRep

Metric	Description	PR	Tool	Done	Ref. by Daniel
CALLING	Number of callers (<5)			[ ]	[ ]
CALLS	Number of called functions (<7)	#59	cflow	[ ]	[x]
COMF	Ratio of comments to statements (>=0.2)	#77	pygount/pmccabe	[ ]	[x]
v_G	Cyclomatic Complexity (<=10)	#53	pmccabe	[ ]	[x]
GOTO	Number of Goto (=0)	#76	qmcalc	[ ]	[x]
LEVEL	Number of nested conditions (<=4)			[ ]	[ ]
PARAM	Number of function parameters (<=5)	#72	cflow	[ ]	[x]
PATH	Number of Paths (<80)			[ ]	[ ]
AP_CG_CYCLE	Recursive Functions (=0)	#67	cflow	[ ]	[ ]
RETURN	Number of returns in function (<=1)			[ ]	[ ]
STMT	Number of statements in function (<=50)	#74	pmccabe	[ ]	[x]
VOCF	Vocabulary of function (<=4)			[ ]	[ ]

The MISRA-related metrics are addressed by the misra check (and not this checker):
NOMV: Violations of the HIS subset of MISRA C rules
NOMVP: Violations of the HIS subset of MISRA C rules by rule

The following metrics are currently not addressed since they are related to project evolution and cannot be evaluated in a single commit/snapshot:
SCHG: Number of statements changed in project
SDEL: Number of statements deleted in project
SI: Stability index of project
SNEW: Number of statements added in project

This PR will be used to discuss the overall implementation of the HIS checker and not technical code corrections of each metric (that should be done on the metric PR).

TODO

• Add tests.

[josecm]

I think an useful information in that table would be if the metric can be computed for each file or has to take the whole project into account.

[AfonsoSantos96]

I think an useful information in that table would be if the metric can be computed for each file or has to take the whole project into account.

That's a good idea! We could add a column that states the granularity of each metric.
I think we could follow this from QA: https://www.qa-systems.com/tools/qa-misra/metrics-and-visualisations/

[danielRep]

Additional information regarding the HIS metrics as defined by the consortium (v1.3.1 - last open specification version).
HIS Source Code Metrics.pdf

[danielRep]

@josecm @miguelafsilva5 Changed the base script for the HIS metrics to give more flexibility to the script:

• -f, --files option expects a list of files to be processed (e.g., -f /path/to/src1.c /path/to/hdr1.c)
• --{metric} options can be used to redefine a default value of the threshold for a specific metric (e.g., --level 200)
• -e, --exclude can be used to exclude a specific metric from the processing (e.g., -e level)

To try this locally use as e.g.: ./his_checker.py -f src/params/params.c --level 200 -e stmt.