internal static async Task <FieldMetricData> ComputeAsync(IFieldSymbol field, SemanticModelProvider semanticModelProvider, CancellationToken cancellationToken)
{
var coupledTypesBuilder = ImmutableHashSet.CreateBuilder <INamedTypeSymbol>();
ImmutableArray <SyntaxReference> declarations = field.DeclaringSyntaxReferences;
long linesOfCode = await MetricsHelper.GetLinesOfCodeAsync(declarations, field, semanticModelProvider, cancellationToken).ConfigureAwait(false);
(int cyclomaticComplexity, ComputationalComplexityMetrics computationalComplexityMetrics) =
await MetricsHelper.ComputeCoupledTypesAndComplexityExcludingMemberDeclsAsync(declarations, field, coupledTypesBuilder, semanticModelProvider, cancellationToken).ConfigureAwait(false);
MetricsHelper.AddCoupledNamedTypes(coupledTypesBuilder, field.Type);
int?depthOfInheritance = null;
int maintainabilityIndex = CalculateMaintainabilityIndex(computationalComplexityMetrics, cyclomaticComplexity);
MetricsHelper.RemoveContainingTypes(field, coupledTypesBuilder);
return(new FieldMetricData(field, maintainabilityIndex, computationalComplexityMetrics,
coupledTypesBuilder.ToImmutable(), linesOfCode, cyclomaticComplexity, depthOfInheritance));
}
private static int CalculateMaintainabilityIndex(
ComputationalComplexityMetrics computationalComplexityMetrics,
int cyclomaticComplexity,
int effectiveChildrenCount)
{
double avgComputationalComplexityVolume = 1.0;
double avgEffectiveLinesOfCode = 0.0;
double avgCyclomaticComplexity = 0.0;
if (effectiveChildrenCount > 0)
{
avgComputationalComplexityVolume = computationalComplexityMetrics.Volume / effectiveChildrenCount;
avgEffectiveLinesOfCode = computationalComplexityMetrics.EffectiveLinesOfCode / effectiveChildrenCount;
avgCyclomaticComplexity = cyclomaticComplexity / effectiveChildrenCount;
}
double logAvgComputationalComplexityVolume = Math.Max(0.0, Math.Log(avgComputationalComplexityVolume)); //avoid Log(0) = -Infinity
double logAvgLinesOfCode = Math.Max(0.0, Math.Log(avgEffectiveLinesOfCode)); //avoid Log(0) = -Infinity
return(MetricsHelper.NormalizeAndRoundMaintainabilityIndex(171 - 5.2 * logAvgComputationalComplexityVolume - 0.23 * avgCyclomaticComplexity - 16.2 * logAvgLinesOfCode));
}
internal static async Task <NamedTypeMetricData> ComputeAsync(INamedTypeSymbol namedType, SemanticModelProvider semanticModelProvider, CancellationToken cancellationToken)
{
var coupledTypesBuilder = ImmutableHashSet.CreateBuilder <INamedTypeSymbol>();
ImmutableArray <SyntaxReference> declarations = namedType.DeclaringSyntaxReferences;
(int cyclomaticComplexity, ComputationalComplexityMetrics computationalComplexityMetrics) =
await MetricsHelper.ComputeCoupledTypesAndComplexityExcludingMemberDeclsAsync(declarations, namedType, coupledTypesBuilder, semanticModelProvider, cancellationToken).ConfigureAwait(false);
// Compat: Filter out nested types as they are children of most closest containing namespace.
var members = namedType.GetMembers().Where(m => m.Kind != SymbolKind.NamedType);
#if LEGACY_CODE_METRICS_MODE
// Legacy mode skips metrics for field/property/event symbols, and explicitly includes accessors as methods.
members = members.Where(m => m.Kind != SymbolKind.Field && m.Kind != SymbolKind.Property && m.Kind != SymbolKind.Event);
#else
// Filter out accessors as they are children of their associated symbols, for which we generate a separate node.
members = members.Where(m => m.Kind != SymbolKind.Method || ((IMethodSymbol)m).AssociatedSymbol == null);
#endif
ImmutableArray <CodeAnalysisMetricData> children = await ComputeAsync(members, semanticModelProvider, cancellationToken).ConfigureAwait(false);
// Heuristic to prevent simple fields (no initializer or simple initializer) from skewing the complexity.
ImmutableHashSet <IFieldSymbol> filteredFieldsForComplexity = getFilteredFieldsForComplexity();
int effectiveChildrenCountForComplexity = 0;
int singleEffectiveChildMaintainabilityIndex = -1;
foreach (CodeAnalysisMetricData child in children)
{
MetricsHelper.AddCoupledNamedTypes(coupledTypesBuilder, child.CoupledNamedTypes);
if (child.Symbol.Kind != SymbolKind.Field ||
filteredFieldsForComplexity.Contains((IFieldSymbol)child.Symbol))
{
singleEffectiveChildMaintainabilityIndex = effectiveChildrenCountForComplexity == 0 && computationalComplexityMetrics.IsDefault ?
child.MaintainabilityIndex :
-1;
effectiveChildrenCountForComplexity++;
cyclomaticComplexity += child.CyclomaticComplexity;
computationalComplexityMetrics = computationalComplexityMetrics.Union(child.ComputationalComplexityMetrics);
}
}
if (cyclomaticComplexity == 0 && !namedType.IsStatic)
{
// Empty named type, account for implicit constructor.
cyclomaticComplexity = 1;
}
int depthOfInheritance = CalculateDepthOfInheritance(namedType);
long linesOfCode = await MetricsHelper.GetLinesOfCodeAsync(declarations, namedType, semanticModelProvider, cancellationToken).ConfigureAwait(false);
int maintainabilityIndex = singleEffectiveChildMaintainabilityIndex != -1 ?
singleEffectiveChildMaintainabilityIndex :
CalculateMaintainabilityIndex(computationalComplexityMetrics, cyclomaticComplexity, effectiveChildrenCountForComplexity);
MetricsHelper.RemoveContainingTypes(namedType, coupledTypesBuilder);
return(new NamedTypeMetricData(namedType, maintainabilityIndex, computationalComplexityMetrics,
coupledTypesBuilder.ToImmutable(), linesOfCode, cyclomaticComplexity, depthOfInheritance, children));
ImmutableHashSet <IFieldSymbol> getFilteredFieldsForComplexity()
{
ImmutableHashSet <IFieldSymbol> .Builder?builderOpt = null;
var orderedFieldDatas = children.Where(c => c.Symbol.Kind == SymbolKind.Field).OrderBy(c => c.MaintainabilityIndex);
var indexThreshold = 99;
foreach (CodeAnalysisMetricData fieldData in orderedFieldDatas)
{
if (fieldData.MaintainabilityIndex > indexThreshold)
{
break;
}
builderOpt ??= ImmutableHashSet.CreateBuilder <IFieldSymbol>();
builderOpt.Add((IFieldSymbol)fieldData.Symbol);
indexThreshold -= 4;
}
return(builderOpt?.ToImmutable() ?? ImmutableHashSet <IFieldSymbol> .Empty);
}
}