89 lines
1.9 KiB
Go
89 lines
1.9 KiB
Go
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package rule
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import (
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"github.com/mgechev/revive/lint"
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"go/ast"
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"go/token"
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)
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// ConstantLogicalExprRule warns on constant logical expressions.
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type ConstantLogicalExprRule struct{}
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// Apply applies the rule to given file.
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func (r *ConstantLogicalExprRule) 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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astFile := file.AST
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w := &lintConstantLogicalExpr{astFile, onFailure}
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ast.Walk(w, astFile)
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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 *ConstantLogicalExprRule) Name() string {
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return "constant-logical-expr"
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}
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type lintConstantLogicalExpr struct {
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file *ast.File
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onFailure func(lint.Failure)
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}
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func (w *lintConstantLogicalExpr) Visit(node ast.Node) ast.Visitor {
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switch n := node.(type) {
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case *ast.BinaryExpr:
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if !w.isOperatorWithLogicalResult(n.Op) {
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return w
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}
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if gofmt(n.X) != gofmt(n.Y) { // check if subexpressions are the same
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return w
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}
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if n.Op == token.EQL {
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w.newFailure(n, "expression always evaluates to true")
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return w
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}
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if w.isInequalityOperator(n.Op) {
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w.newFailure(n, "expression always evaluates to false")
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return w
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}
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w.newFailure(n, "left and right hand-side sub-expressions are the same")
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}
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return w
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}
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func (w *lintConstantLogicalExpr) isOperatorWithLogicalResult(t token.Token) bool {
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switch t {
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case token.LAND, token.LOR, token.EQL, token.LSS, token.GTR, token.NEQ, token.LEQ, token.GEQ:
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return true
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}
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return false
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}
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func (w *lintConstantLogicalExpr) isInequalityOperator(t token.Token) bool {
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switch t {
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case token.LSS, token.GTR, token.NEQ, token.LEQ, token.GEQ:
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return true
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}
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return false
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}
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func (w lintConstantLogicalExpr) 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: "logic",
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Failure: msg,
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})
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}
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