103 lines
2.0 KiB
Go
103 lines
2.0 KiB
Go
package rule
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import (
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"fmt"
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"go/ast"
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"github.com/mgechev/revive/lint"
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)
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// UnusedParamRule lints unused params in functions.
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type UnusedParamRule struct{}
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// Apply applies the rule to given file.
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func (r *UnusedParamRule) 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 := lintUnusedParamRule{onFailure: 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 *UnusedParamRule) Name() string {
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return "unused-parameter"
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}
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type lintUnusedParamRule struct {
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onFailure func(lint.Failure)
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}
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func (w lintUnusedParamRule) 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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params := retrieveNamedParams(n.Type.Params)
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if len(params) < 1 {
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return nil // skip, func without parameters
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}
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if n.Body == nil {
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return nil // skip, is a function prototype
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}
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// inspect the func body looking for references to parameters
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fselect := func(n ast.Node) bool {
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ident, isAnID := n.(*ast.Ident)
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if !isAnID {
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return false
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}
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_, isAParam := params[ident.Obj]
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if isAParam {
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params[ident.Obj] = false // mark as used
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}
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return false
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}
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_ = pick(n.Body, fselect, nil)
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for _, p := range n.Type.Params.List {
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for _, n := range p.Names {
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if params[n.Obj] {
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w.onFailure(lint.Failure{
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Confidence: 1,
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Node: n,
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Category: "bad practice",
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Failure: fmt.Sprintf("parameter '%s' seems to be unused, consider removing or renaming it as _", n.Name),
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})
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}
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}
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}
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return nil // full method body already inspected
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}
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return w
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}
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func retrieveNamedParams(params *ast.FieldList) map[*ast.Object]bool {
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result := map[*ast.Object]bool{}
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if params.List == nil {
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return result
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}
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for _, p := range params.List {
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for _, n := range p.Names {
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if n.Name == "_" {
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continue
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}
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result[n.Obj] = true
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}
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}
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return result
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}
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