The CAST Quality Model contains various metrics that are classed as "Complexity metrics", i.e. metrics that measure the complexity of artifacts in an application. This page contains a basic description of the mechanisms used to determine the complexity of a given artifact.

# CAST Complexity Metrics

CAST provides data for the following "Complexity metrics":

- Cyclomatic Complexity
- Basic Cyclomatic Complexity
- Essential Complexity
- Integration Complexity
- Cost Complexity - used in the Cost Estimation feature

# How is complexity calculated?

## Cyclomatic, Basic Cyclomatic, Essential, Integration

During an analysis and subsequent snapshot generation, CAST determines a complexity score for an artifact by counting the number of statements (i.e. IF, ELSE-IF, WHILE, DO etc.) it encounters - an increment of one per statement encountered is used. In addition, nested statements are also counted, which contribute to the overall complexity score.

Each Complexity metric takes into account different statements - these are listed below.

### Cyclomatic Complexity

To compute this metric, a counter is incremented by one each time one of the following statements is encountered:

- IF
- ELSE-IF
- AND-OR
- CASE
- CATCH
- CONTINUE (only in loops)
- DO-WHILE
- WHILE
- FOR
- TRY

### Basic Cyclomatic Complexity

To compute this metric, a counter is incremented by one each time one of the following statements is encountered:

- IF
- ELSE-IF
- CASE
- CATCH
- CONTINUE (only in loops)
- DO-WHILE
- WHILE
- FOR
- TRY

### Essential Complexity

Two statement types are taken into account for this metric:

#### Primitive Statements

- IF
- ELSE-IF
- AND-OR
- SWITCH
- CASE
- TRY
- CATCH
- DO-WHILE
- WHILE
- FOR

#### Complex Statements

- BREAK (Only in loops)
- CONTINUE (Only in loops)
- GOTO
- RAISE

#### How does it work?

CAST walks through the **Primitive** statements in the artifact and then the **Complex** statements. If a statement is encountered in a Primitive statement but it is not determined to match one of the predefined **Complex** statements then the branch is "reduced" (i.e.skipped) back to the first **Complex** statement that was encountered (or the root if none). For example:

##### Complex statement encountered

Function XX => Init = 1 Prim 1 => +1 Prim 2 => +1 Prim 3 => +1 Complex 1 => Complex => No reduction Result = 4

##### Complex statement followed by non-Complex (reduction)

Function XX => Init = 1 Prim 1 => +1 Complex 1 => Complex => No reduction Prim 2 => +1 Prim 3 => +1 Statement => Non-Complex => Reduction to the first Complex statement Result = 2

##### Non-Complex statement

Function XX => Init = 1 Prim 1 => +1 Prim 2 => +1 Prim 3 => +1 Statement => No Complex => Reduction to the root Result: EvG = 1

### Integration Complexity

This metric functions in exactly the same way as Essential Complexity (described above) except that the list of Complex Statements is different:

#### Primitive Statements

- IF
- ELSE-IF
- AND-OR
- SWITCH
- CASE
- TRY
- CATCH
- DO-WHILE
- WHILE
- FOR

#### Complex Statements

- CALL

## Cost

Cost Complexity is calculated in a different way to other Complexity metrics. It takes into account complexity scores for other types of complexity (such as Cylcomatic Complexity) and aggregates them to provide a score for Cost Complexity.

### Items taken into account

The following are taken into account:

#### Lack of Comment index

Artifacts are positioned based on their comment/code ratio using the following thresholds:

- Average Comment/Code ratio: 15
- High Comment/Code Ratio: 7
- Very High Comment/Code Ratio: 3

#### Cyclomatic Complexity index

Artifacts are positioned based on their Cyclomatic Complexity score as follows:

Moderate Cyclomatic Complexity: for all artifacts having a result for the metric 65503 (Moderate Complexity Artifacts)

High Cyclomatic Complexity: for all artifacts having a result for the metric 65504 (High Complexity Artifacts)

Very High Cyclomatic Complexity: for all artifacts having a result for the metric 65505 (Very High Complexity Artifacts)

#### SQL Complexity index

Artifacts are positioned based on their SQL Complexity score as follows:

Moderate SQL Complexity: for all artifacts having a result for the metric 65803 (Moderate SQL Complexity Artifacts)

High SQL Complexity: for all artifacts having a result for the metric 65804 (High SQL Complexity Artifacts)

Very High SQL Complexity: for all artifacts having a result for the metric 65805 (Very High SQL Complexity Artifacts)

#### Artifact Granularity index

Artifacts are positioned based on their Size Distribution score as follows:

Average Granularity: for all artifacts having a result for the metric 65102 (Average Size Artifacts)

High Granularity: for all artifacts having a result for the metric 65103 (Large Size Artifacts)

Very High Granularity: for all artifacts having a result for the metric 65104 (Very Large Size Artifacts)

#### Artifact Coupling index

Artifacts are positioned based on their Coupling Distribution score as follows:

Average Coupling: for all artifacts having a result for the metric 65302 (Average Coupling Artifacts)

High Coupling: for all artifacts having a result for the metric 65303 (High Coupling Artifacts)

Very High Coupling: for all artifacts having a result for the metric 65304 (Very High Coupling Artifacts)

### Cost Complexity calculation

Once the above scores are determined for an artifact, the Cost Complexity score is then calculated as follows:

#### Very High Cost Complexity

Cost Complexity will be Very High when ONE of the following is true:

**Cyclomatic Complexity index**is Very High**SQL Complexity index**is Very High**Artifact Granularity index**is Very High__and__**Lack of Comment index**is Very High__and__**Artifact Coupling index**is Very High

#### High Cost Complexity

Cost Complexity will be High when ONE of the following is true:

**Cyclomatic Complexity index**is Moderate__and__**SQL Complexity index**is Moderate__and__(**Artifact Granularity index**is Very High__or__**Lack of Comment index**is Very High or**Artifact Coupling index**is Very High)**Cyclomatic Complexity index**is High**Artifact Granularity index**is High__and__**Lack of Comment index**is High__and__**Artifact Coupling Index**is High

#### Moderate Cost Complexity

Cost Complexity will be Moderate when ONE of the following is true:

**Cyclomatic Complexity index**is Low__and__**SQL Complexity index**is Low__and__(**Artifact Granularity index**is High__and__**Lack of Comment index**is High__and__**Artifact Coupling index**is High)**Cyclomatic Complexity index**is Moderate**SQL Complexity index**is Moderate**Artifact Granularity index**is Moderate__and__**Lack of Comment index**is Moderate__and__**Artifact Coupling index**is Moderate