123 lines
2.9 KiB
Markdown
123 lines
2.9 KiB
Markdown
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# nestif
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[](http://godoc.org/github.com/nakabonne/nestif)
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Reports deeply nested if statements in Go code, by calculating its complexities based on the rules defined by the [Cognitive Complexity white paper by G. Ann Campbell](https://www.sonarsource.com/docs/CognitiveComplexity.pdf).
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It helps you find if statements that make your code hard to read, and clarifies which parts to refactor.
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## Installation
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```
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go get github.com/nakabonne/nestif/cmd/nestif
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```
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## Usage
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### Quick Start
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```bash
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nestif
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```
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The `...` glob operator is supported, and the above is an equivalent of:
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```bash
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nestif ./...
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```
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One or more files and directories can be specified in a single command:
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```bash
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nestif dir/foo.go dir2 dir3/...
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```
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Packages can be specified as well:
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```bash
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nestif github.com/foo/bar example.com/bar/baz
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```
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### Options
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```
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usage: nestif [<flag> ...] <Go files or directories or packages> ...
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-e, --exclude-dirs strings regexps of directories to be excluded for checking; comma-separated list
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--json emit json format
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--min int minimum complexity to show (default 1)
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--top int show only the top N most complex if statements (default 10)
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-v, --verbose verbose output
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```
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### Example
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Let's say you write:
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```go
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package main
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func _() {
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if foo {
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if bar {
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}
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}
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if baz == "baz" {
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if qux {
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if quux {
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}
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}
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}
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}
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```
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And give it to nestif:
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```console
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$ nestif foo.go
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foo.go:9:2: `if baz == "baz"` is nested (complexity: 3)
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foo.go:4:2: `if foo` is nested (complexity: 1)
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```
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Note that the results are sorted in descending order of complexity. In addition, it shows only the top 10 most complex if statements by default, and you can specify how many to show with `-top` flag.
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### Rules
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It calculates the complexities of if statements according to the nesting rules of Cognitive Complexity.
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Since the more deeply-nested your code gets, the harder it can be to reason about, it assesses a nesting increment for it:
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```go
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if condition1 {
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if condition2 { // +1
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if condition3 { // +2
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if condition4 { // +3
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}
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}
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}
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}
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```
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`else` and `else if` increase complexity by one wherever they are because the mental cost has already been paid when reading the if:
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```go
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if condition1 {
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if condition2 { // +1
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if condition3 { // +2
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} else if condition4 { // +1
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} else { // +1
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if condition5 { // +3
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}
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}
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}
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}
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```
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## Inspired by
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- [uudashr/gocognit](https://github.com/uudashr/gocognit)
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- [fzipp/gocyclo](https://github.com/fzipp/gocyclo)
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## Further reading
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Please see the [Cognitive Complexity: A new way of measuring understandability](https://www.sonarsource.com/docs/CognitiveComplexity.pdf) white paper by G. Ann Campbell for more detail on Cognitive Complexity.
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