Metric ID

`sfdesignlayer.StateflowHalsteadComplexity`

Description

The Halstead complexity metrics measure the size and complexity of code, which can help you monitor code quality, identify complex areas in the design, and address software maintainability concerns.

Use this metric to count the operators and operands in Stateflow® charts and calculate design volume and difficulty using the Halstead complexity metrics.

Computation Details

Operators and Operands

An operator specifies an action that influences the content of a variable. An operand is the basic logical unit that the operator acts on.

The metric:

• Uses the following definitions:

• Ignores objects that you comment out.

• Ignores unresolved symbols.

• Ignores empty lines and empty columns in the Condition Table and Action Table.

• Ignores Stateflow states and transitions that have syntax errors.

The metric calculates the Halstead volume, `V`, using the equation $V=\left(N1+N2\right)×{\mathrm{log}}_{2}\left(n1+n2\right)$. `N1` is the number of total operators, `N2` is the total number of operands, `n1` is the number of unique operators, and `n2` is the number of unique operands.

The metric calculates the Halstead difficulty, `D`, using the equation $D=\frac{n1}{2}×\frac{N2}{n2}$. `n1` is the number of unique operators, `N2` is the total number of operands, and `n2` is the number of unique operands.

Collection

To collect data for this metric, execute the metric engine and use `getMetrics` with the metric ID `sfdesignlayer.StateflowHalsteadComplexity`.

```metric_engine = metric.Engine; execute(metric_engine,"sfdesignlayer.StateflowHalsteadComplexity"); results = getMetrics(metric_engine,"sfdesignlayer.StateflowHalsteadComplexity")```

Results

This metric returns metric results for each Stateflow design layer in the units and components in your project. A Stateflow design layer is an artifact, like a Stateflow chart, state, or truth table, that has its own canvas in Stateflow.

For each Stateflow design layer, the metric returns a `metric.Result` object with properties including:

• `Value` — Structure with fields for:

• `TotalOperators` — Number of Stateflow operators and MATLAB operators

• `TotalOperatorsSF` — Number of Stateflow operators

• `TotalOperatorsML` — Number of MATLAB operators

• `UniqueOperators` — Number of unique Stateflow operators and MATLAB operators

• `UniqueOperatorsSF` — Number of unique Stateflow operators

• `UniqueOperatorsML` — Number of unique MATLAB operators

• `TotalOperands` — Number of Stateflow operands and MATLAB operands

• `TotalOperandsSF` — Number of Stateflow operands

• `TotalOperandsML` — Number of MATLAB operands

• `UniqueOperands` — Sum of unique Stateflow operands, `UniqueOperandsSF`, and unique MATLAB operands, `UniqueOperandsML`

• `UniqueOperandsSF` — Each operand in Stateflow is unique, so `UniqueOperandsSF` is equal to `TotalOperandsSF`

• `UniqueOperandsML` — Number of unique MATLAB operands

• `Volume` — Size of the design layer

• `Difficulty` — Estimate of how difficult the design layer is to read and write

• `Scope` — Structure with information about the design layer

For information on how the metric calculates the metric results, see Computation Details.

References

[1] Halstead, Maurice H. Elements of Software Science. New York: North Holland, 1979.

[2] Stürmer, Ingo, Hartmut Pohlheim, and Thorsten Rogier. 2010. "Berechnung und Visualisierung der Modellkomplexität bei der modellbasierten Entwicklung sicherheitsrelevanter Software." In Automotive - Safety & Security, edited by B. Keller et al., 69-82. Aachen: Shaker Verlag.

[3] Yu, Sheng, and Shijie Zhou. “A Survey on Metric of Software Complexity.” In 2010 2nd IEEE International Conference on Information Management and Engineering, 352–56, 2010. https://doi.org/10.1109/ICIME.2010.5477581.