sa1024.go raw

   1  package sa1024
   2  
   3  import (
   4  	"go/constant"
   5  	"sort"
   6  
   7  	"honnef.co/go/tools/analysis/callcheck"
   8  	"honnef.co/go/tools/analysis/lint"
   9  	"honnef.co/go/tools/internal/passes/buildir"
  10  
  11  	"golang.org/x/tools/go/analysis"
  12  )
  13  
  14  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  15  	Analyzer: &analysis.Analyzer{
  16  		Name:     "SA1024",
  17  		Requires: []*analysis.Analyzer{buildir.Analyzer},
  18  		Run:      callcheck.Analyzer(rules),
  19  	},
  20  	Doc: &lint.RawDocumentation{
  21  		Title: `A string cutset contains duplicate characters`,
  22  		Text: `The \'strings.TrimLeft\' and \'strings.TrimRight\' functions take cutsets, not
  23  prefixes. A cutset is treated as a set of characters to remove from a
  24  string. For example,
  25  
  26      strings.TrimLeft("42133word", "1234")
  27  
  28  will result in the string \'"word"\' – any characters that are 1, 2, 3 or
  29  4 are cut from the left of the string.
  30  
  31  In order to remove one string from another, use \'strings.TrimPrefix\' instead.`,
  32  		Since:    "2017.1",
  33  		Severity: lint.SeverityWarning,
  34  		MergeIf:  lint.MergeIfAny,
  35  	},
  36  })
  37  
  38  var Analyzer = SCAnalyzer.Analyzer
  39  
  40  var rules = map[string]callcheck.Check{
  41  	"strings.Trim":      check,
  42  	"strings.TrimLeft":  check,
  43  	"strings.TrimRight": check,
  44  }
  45  
  46  func check(call *callcheck.Call) {
  47  	arg := call.Args[1]
  48  	if !isUniqueStringCutset(arg.Value) {
  49  		const MsgNonUniqueCutset = "cutset contains duplicate characters"
  50  		arg.Invalid(MsgNonUniqueCutset)
  51  	}
  52  }
  53  
  54  func isUniqueStringCutset(v callcheck.Value) bool {
  55  	if c := callcheck.ExtractConstExpectKind(v, constant.String); c != nil {
  56  		s := constant.StringVal(c.Value)
  57  		rs := runeSlice(s)
  58  		if len(rs) < 2 {
  59  			return true
  60  		}
  61  		sort.Sort(rs)
  62  		for i, r := range rs[1:] {
  63  			if rs[i] == r {
  64  				return false
  65  			}
  66  		}
  67  	}
  68  	return true
  69  }
  70  
  71  type runeSlice []rune
  72  
  73  func (rs runeSlice) Len() int               { return len(rs) }
  74  func (rs runeSlice) Less(i int, j int) bool { return rs[i] < rs[j] }
  75  func (rs runeSlice) Swap(i int, j int)      { rs[i], rs[j] = rs[j], rs[i] }
  76