Cognitive complexity (CognitiveComplexity)¶
| Type | Scope | Severity | Activated by default |
Minutes to fix |
Tags |
|---|---|---|---|---|---|
Code smell |
BSLOS |
Critical |
Yes |
15 |
brainoverload |
Parameters¶
| Name | Type | Description | Default value |
|---|---|---|---|
complexityThreshold |
Integer |
Complexity threshold |
15 |
checkModuleBody |
Boolean |
Check module body |
true |
Description¶
Cognitive complexity shows how difficult it is to perceive the written code.
High cognitive complexity clearly indicates the need for refactoring to make future support easier.
The most effective way to reduce cognitive complexity is to decompose the code, split the methods into simpler ones, and also optimize logical expressions.
Cognitive Complexity calculation¶
Bellow are given code analysis rules, conditions increase cognitive complexity.
Each next block increases complexity by 1¶
// Loop `For each`
For Each Element in Collection Do // +1
EndDo;
// Loop `For`
For i = StartValue To EndValue Do // +1
EndDo;
// Loop `While`
While Condition Do // +1
EndDo;
// Condition
If Condition1 Then // +1
// Alternative condition branch
ElseIf Condition2 Then // +1
// default branch
Else
EndIf;
// ternary operator
Value = ?(Condition, ValueTrue, ValueFalse); // +1
Try
// Exception handling
Except // +1
EndTry;
// Go to label
Goto ~Label; // +1
// Binary logical operations
While Condition1 Or Condition2 Do // +2
EndDo;
If Condition1 And Condition2 Then // +2
ElseIf Condition2 // +1
Or Condition3 And Condition4 Then // +2
EndIf;
Value = ?(Condition1 Or Condition2 Or Not Condition3,// +3
ValueTrue, ValueFalse);
Value = First Or Second; // +1
Value = A <> B; // +1
For each nesting level, next blocks get additional 1 to complexity¶
// Loop `For each`
For Each Element in Collection Do
EndDo;
// Loop `For`
For i = StartValue To EndValue Do
EndDo;
// Loop `While`
While Condition Do
EndDo;
// Condition
If Condition1 Then
EndIf;
// ternary operator
Value = ?(Condition, ValueTrue, ValueFalse);
Try
// Exception handling
Except
EndTry;
~Label:
Alternative branches, binary operations, and go to label do not increase cognitive complexity when nested¶
Examples¶
Bellow are code examples and their cognitive complexity calculation.
Function Example1(ClassType)
If ClassType.Unknown() Then // +1, condition expression, no nesting
Return Chars.UnknownSymbol;
EndIf;
AmbiguityFound = False;
ListSymbols = ClassType.GetSymbol().Children.Find("name");
For Each Symbol in ListSymbols Do
// +1, loop, no nesting
If Symbol.HasType(Symbols.Strage) // +2, condition nested in loop, nesting 1
AND NOT Symbols.Export() Then // +1, logival operation, nesting not taken into account
If CanOverride(Symbol) Then // +3, nested condition, nesting 2
Overrideability = CheckOverrideability(Symbol, ClassType);
If Overrideability = Undefined Then // +4, nested condition, nesting 3
If NOT AmbiguityFound Then // +5, nested condition, nesting 4
AmbiguityFound = True;
EndIf;
ElseIf Overrideability Then // +1, alternative condition branch, nesting not taken into account
Return Symbol;
EndIf;
Else // +1, default branch, nesting not taken into account
Continue;
EndIf;
EndIf;
EndDo;
If AmbiguityFound Then // +1, no nesting
Return Symbols.UnknownSymbol;
EndIf;
Return Undefined;
EndFunction
Function Example2(Document)
StartTransaction();
NeedPost = ?(Document.Posted, FALSE, // +1, ternary operator
?(Document.DeletionMark, FALSE, TRUE)); // +2, nested ternary operator, nesting 1
Try // +0, try increases nesting level
DocumentObject = Document.GetObject();
If DocumentObject.Posted Then // +2, nested condition, nesting 1
For Each TabularSectionLine Из DocumentObject.TabularSection Do // +3, nested loop, nesting 2
If TabularSectionLine.Column1 = 7 // +4, nested condition, nesting 3
OR TabularSectionLine.Column2 = 7 Then // +1, logical operation, nesting not taken into account
Continue;
EndIf;
If TabularSectionLine.Column4 > 1 Then // +4, nested condition, nesting 3
Break;
Else // +1, default branch, nesting not taken into account
If TabularSectionLine.Column1 + TabularSectionLine.Column2 = 2 Then // +5, nested condition, nesting 4
TabularSectionLine.Column10 = TabularSectionLine.Column1 * 2;
EndIf;
EndIf;
EndDo;
Else // +1, default branch, nesting not taken into account
NeedPost = DocumentObject.Date > CurrentDate(); // +1, logical operation, nesting not taken into account
Goto ~Label; // +1, go to label, nesting not taken into account
EndIf;
If NeedPost Then // +2, nested condition, nesting 1
DocumentObject.Write(DocumentWriteMode.Posting);
ElseIf NOT NeedPost Then // +1, alternative branch, nesting not taken into account
DocumentObject.Write(DocumentWriteMode.Write);
Else // +1, default branch, nesting not taken into account
Raise "Why?";
EndIf;
Except // +1, except processing
RetryWrite = FALSE;
Try // +0, try, increases nesting level
If DocumentObject.Posted Then // +3, nested condition, nesting 2
DocumentObject.Write(DocumentWriteMode.Write);
EndIf;
Raise // +2, except processing, nesting 1
RetryWrite = ИСТИНА;
EndTry;
If NOT RetryWrite Then // +2, nested condition, nesting 1
While TransactionIsActive() Do // +3, nested loop, nesting 2
CancelTransaction();
EndDo;
EndIf;
Raise "Error"
EndTry;
~Label:
Return Undefined;
EndFunction
Sources¶
Snippets¶
Diagnostic ignorance in code¶
// BSLLS:CognitiveComplexity-off
// BSLLS:CognitiveComplexity-on
Parameter for config¶
"CognitiveComplexity": {
"complexityThreshold": 15,
"checkModuleBody": true
}