gocyclo

You can exclude specific functions from complexity analysis by adding the //gocyclo:ignore directive directly above the function or variable declaration.

//gocyclo:ignore
func f1() {
	// ...
}
    
//gocyclo:ignore
var f2 = func() {
	// ...
}

To install the gocyclo command, use the go install command. Ensure that $GOPATH/bin is in your PATH so you can run the binary directly.

$ go install github.com/fzipp/gocyclo/cmd/gocyclo@latest

Common usage patterns for gocyclo include:

• Analyzing the current directory: gocyclo .
• Finding the top 10 most complex functions: gocyclo -top 10 src/
• Finding functions with complexity over 25: gocyclo -over 25 docker
• Calculating average complexity: gocyclo -avg .
• Filtering out specific directories (like vendor or tests) using regex: gocyclo -top 20 -ignore "_test|Godeps|vendor/" .

$ gocyclo .
$ gocyclo main.go
$ gocyclo -top 10 src/
$ gocyclo -over 25 docker
$ gocyclo -avg .
$ gocyclo -top 20 -ignore "_test|Godeps|vendor/" .
$ gocyclo -over 3 -avg gocyclo/

The gocyclo command calculates the cyclomatic complexity of functions in Go source code. You can provide Go files or directories as arguments.

Output Format: Each line of output follows this pattern: <complexity> <package> <function> <file:line:column>

$ gocyclo .
$ gocyclo main.go

The SortAndFilter(top, over int) Stats method sorts the Stats slice in descending order (modifying the original slice) and returns a subset based on the following rules:

• top: The maximum number of entries to return. If set to -1, the result is not limited by count.
• over: The minimum complexity threshold. Only functions with a complexity strictly greater than over are included. If over <= 0, the result is not limited by complexity.

This is useful for identifying the most complex functions in a codebase.

The Complexity function calculates the cyclomatic complexity of a Go function or method. It accepts an ast.Node which must be either a *ast.FuncDecl (function declaration) or a *ast.FuncLit (function literal/anonymous function).

Complexity is calculated by starting at 1 and incrementing for each of the following control flow structures:

• *ast.IfStmt (if statements)
• *ast.ForStmt (for loops)
• *ast.RangeStmt (range loops)
• *ast.CaseClause (switch/select cases, excluding default cases)
• *ast.CommClause (select communication cases, excluding default cases)
• *ast.BinaryExpr using token.LAND (&&) or token.LOR (||) operators.

Use the following methods on a Stats slice to get aggregate metrics:

• TotalComplexity() uint64: Returns the sum of all cyclomatic complexities in the slice.
• AverageComplexity() float64: Returns the mean complexity of all functions in the slice.

Use Analyze(paths []string, ignore *regexp.Regexp) Stats to calculate the cyclomatic complexities of functions and methods within specified Go source files or directories. If a path is a directory, the function recursively analyzes all Go files within it.

You can provide an optional ignore regular expression to skip files that match the pattern. If ignore is nil, no files are skipped.

Use the following flags to filter results or change the output behavior of gocyclo: