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emptycase.go
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emptycase.go
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package emptycase
import (
"github.com/gostaticanalysis/comment"
"go/ast"
"strings"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
"golang.org/x/tools/go/ast/inspector"
)
const doc = "emptycase find empty cases"
// Analyzer is ...
var Analyzer = &analysis.Analyzer{
Name: "emptycase",
Doc: doc,
Run: run,
Requires: []*analysis.Analyzer{
inspect.Analyzer,
},
}
var analyzerTest = false
func run(pass *analysis.Pass) (interface{}, error) {
commentMap := comment.New(pass.Fset, pass.Files)
// Report a case with no body.
// However, if a comment is attached to it, it is considered an intentional empty case and not reported.
var emptyCaseChecker = func(caseNode ast.Node, body []ast.Stmt) {
if len(body) != 0 {
return
}
commentGroup := commentMap.Comments(caseNode)
if len(commentGroup) == 0 {
pass.Reportf(caseNode.Pos(), "empty case")
return
}
if analyzerTest {
// Comments that indicate the expected value of the analyzer test are not considered comments.
if len(commentGroup) == 1 && strings.HasPrefix(strings.TrimLeft(commentGroup[0].List[0].Text[2:], " "), "want") {
pass.Reportf(caseNode.Pos(), "empty case")
}
}
}
inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
nodeFilter := []ast.Node{
(*ast.CaseClause)(nil),
(*ast.CommClause)(nil),
}
inspect.Preorder(nodeFilter, func(n ast.Node) {
switch n := n.(type) {
case *ast.CaseClause:
emptyCaseChecker(n, n.Body)
case *ast.CommClause:
emptyCaseChecker(n, n.Body)
}
})
return nil, nil
}