88 lines
1.9 KiB
Go
88 lines
1.9 KiB
Go
package rule
|
|
|
|
import (
|
|
"github.com/mgechev/revive/lint"
|
|
"go/ast"
|
|
"go/token"
|
|
)
|
|
|
|
// ConstantLogicalExprRule warns on constant logical expressions.
|
|
type ConstantLogicalExprRule struct{}
|
|
|
|
// Apply applies the rule to given file.
|
|
func (r *ConstantLogicalExprRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
|
|
var failures []lint.Failure
|
|
|
|
onFailure := func(failure lint.Failure) {
|
|
failures = append(failures, failure)
|
|
}
|
|
|
|
astFile := file.AST
|
|
w := &lintConstantLogicalExpr{astFile, onFailure}
|
|
ast.Walk(w, astFile)
|
|
return failures
|
|
}
|
|
|
|
// Name returns the rule name.
|
|
func (r *ConstantLogicalExprRule) Name() string {
|
|
return "constant-logical-expr"
|
|
}
|
|
|
|
type lintConstantLogicalExpr struct {
|
|
file *ast.File
|
|
onFailure func(lint.Failure)
|
|
}
|
|
|
|
func (w *lintConstantLogicalExpr) Visit(node ast.Node) ast.Visitor {
|
|
switch n := node.(type) {
|
|
case *ast.BinaryExpr:
|
|
if !w.isOperatorWithLogicalResult(n.Op) {
|
|
return w
|
|
}
|
|
|
|
if gofmt(n.X) != gofmt(n.Y) { // check if subexpressions are the same
|
|
return w
|
|
}
|
|
|
|
if n.Op == token.EQL {
|
|
w.newFailure(n, "expression always evaluates to true")
|
|
return w
|
|
}
|
|
|
|
if w.isInequalityOperator(n.Op) {
|
|
w.newFailure(n, "expression always evaluates to false")
|
|
return w
|
|
}
|
|
|
|
w.newFailure(n, "left and right hand-side sub-expressions are the same")
|
|
}
|
|
|
|
return w
|
|
}
|
|
|
|
func (w *lintConstantLogicalExpr) isOperatorWithLogicalResult(t token.Token) bool {
|
|
switch t {
|
|
case token.LAND, token.LOR, token.EQL, token.LSS, token.GTR, token.NEQ, token.LEQ, token.GEQ:
|
|
return true
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
func (w *lintConstantLogicalExpr) isInequalityOperator(t token.Token) bool {
|
|
switch t {
|
|
case token.LSS, token.GTR, token.NEQ, token.LEQ, token.GEQ:
|
|
return true
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
func (w lintConstantLogicalExpr) newFailure(node ast.Node, msg string) {
|
|
w.onFailure(lint.Failure{
|
|
Confidence: 1,
|
|
Node: node,
|
|
Category: "logic",
|
|
Failure: msg,
|
|
})
|
|
}
|