107 lines
2.1 KiB
Go
107 lines
2.1 KiB
Go
package rule
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import (
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"go/ast"
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"go/token"
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"github.com/mgechev/revive/lint"
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)
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// UnnecessaryStmtRule warns on unnecessary statements.
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type UnnecessaryStmtRule struct{}
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// Apply applies the rule to given file.
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func (r *UnnecessaryStmtRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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onFailure := func(failure lint.Failure) {
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failures = append(failures, failure)
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}
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w := lintUnnecessaryStmtRule{onFailure}
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ast.Walk(w, file.AST)
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return failures
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}
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// Name returns the rule name.
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func (r *UnnecessaryStmtRule) Name() string {
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return "unnecessary-stmt"
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}
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type lintUnnecessaryStmtRule struct {
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onFailure func(lint.Failure)
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}
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func (w lintUnnecessaryStmtRule) Visit(node ast.Node) ast.Visitor {
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switch n := node.(type) {
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case *ast.FuncDecl:
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if n.Body == nil || n.Type.Results != nil {
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return w
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}
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stmts := n.Body.List
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if len(stmts) == 0 {
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return w
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}
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lastStmt := stmts[len(stmts)-1]
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rs, ok := lastStmt.(*ast.ReturnStmt)
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if !ok {
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return w
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}
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if len(rs.Results) == 0 {
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w.newFailure(lastStmt, "omit unnecessary return statement")
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}
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case *ast.SwitchStmt:
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w.checkSwitchBody(n.Body)
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case *ast.TypeSwitchStmt:
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w.checkSwitchBody(n.Body)
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case *ast.CaseClause:
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if n.Body == nil {
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return w
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}
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stmts := n.Body
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if len(stmts) == 0 {
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return w
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}
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lastStmt := stmts[len(stmts)-1]
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rs, ok := lastStmt.(*ast.BranchStmt)
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if !ok {
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return w
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}
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if rs.Tok == token.BREAK && rs.Label == nil {
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w.newFailure(lastStmt, "omit unnecessary break at the end of case clause")
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}
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}
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return w
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}
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func (w lintUnnecessaryStmtRule) checkSwitchBody(b *ast.BlockStmt) {
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cases := b.List
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if len(cases) != 1 {
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return
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}
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cc, ok := cases[0].(*ast.CaseClause)
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if !ok {
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return
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}
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if len(cc.List) > 1 { // skip cases with multiple expressions
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return
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}
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w.newFailure(b, "switch with only one case can be replaced by an if-then")
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}
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func (w lintUnnecessaryStmtRule) newFailure(node ast.Node, msg string) {
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w.onFailure(lint.Failure{
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Confidence: 1,
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Node: node,
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Category: "style",
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Failure: msg,
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})
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}
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