prysm-pulse/tools/analyzers/comparesame/analyzer.go
2021-02-12 17:04:45 -06:00

68 lines
1.7 KiB
Go

// Package comparesame implements a static analyzer to ensure that code does not contain
// comparisons of identical expressions.
package comparesame
import (
"bytes"
"errors"
"go/ast"
"go/printer"
"go/token"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
"golang.org/x/tools/go/ast/inspector"
)
// Doc explaining the tool.
const Doc = "Tool to detect comparison (==, !=, >=, <=, >, <) of identical expressions."
const messageTemplate = "Boolean expression has identical expressions on both sides. The result is always %v."
// Analyzer runs static analysis.
var Analyzer = &analysis.Analyzer{
Name: "comparesame",
Doc: Doc,
Requires: []*analysis.Analyzer{inspect.Analyzer},
Run: run,
}
func run(pass *analysis.Pass) (interface{}, error) {
inspection, ok := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
if !ok {
return nil, errors.New("analyzer is not type *inspector.Inspector")
}
nodeFilter := []ast.Node{
(*ast.BinaryExpr)(nil),
}
inspection.Preorder(nodeFilter, func(node ast.Node) {
expr, ok := node.(*ast.BinaryExpr)
if !ok {
return
}
switch expr.Op {
case token.EQL, token.NEQ, token.GEQ, token.LEQ, token.GTR, token.LSS:
var xBuf, yBuf bytes.Buffer
if err := printer.Fprint(&xBuf, pass.Fset, expr.X); err != nil {
pass.Reportf(expr.X.Pos(), err.Error())
}
if err := printer.Fprint(&yBuf, pass.Fset, expr.Y); err != nil {
pass.Reportf(expr.Y.Pos(), err.Error())
}
if xBuf.String() == yBuf.String() {
switch expr.Op {
case token.EQL, token.NEQ, token.GEQ, token.LEQ:
pass.Reportf(expr.OpPos, messageTemplate, true)
case token.GTR, token.LSS:
pass.Reportf(expr.OpPos, messageTemplate, false)
}
}
}
})
return nil, nil
}