github.com/amarpal/go-tools@v0.0.0-20240422043104-40142f59f616/simple/s1010/s1010.go (about)

     1  package s1010
     2  
     3  import (
     4  	"go/ast"
     5  
     6  	"github.com/amarpal/go-tools/analysis/code"
     7  	"github.com/amarpal/go-tools/analysis/edit"
     8  	"github.com/amarpal/go-tools/analysis/facts/generated"
     9  	"github.com/amarpal/go-tools/analysis/lint"
    10  	"github.com/amarpal/go-tools/analysis/report"
    11  	"github.com/amarpal/go-tools/pattern"
    12  
    13  	"golang.org/x/tools/go/analysis"
    14  	"golang.org/x/tools/go/analysis/passes/inspect"
    15  )
    16  
    17  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
    18  	Analyzer: &analysis.Analyzer{
    19  		Name:     "S1010",
    20  		Run:      run,
    21  		Requires: []*analysis.Analyzer{inspect.Analyzer, generated.Analyzer},
    22  	},
    23  	Doc: &lint.Documentation{
    24  		Title: `Omit default slice index`,
    25  		Text: `When slicing, the second index defaults to the length of the value,
    26  making \'s[n:len(s)]\' and \'s[n:]\' equivalent.`,
    27  		Since:   "2017.1",
    28  		MergeIf: lint.MergeIfAny,
    29  	},
    30  })
    31  
    32  var Analyzer = SCAnalyzer.Analyzer
    33  
    34  var checkSlicingQ = pattern.MustParse(`(SliceExpr x@(Object _) low (CallExpr (Builtin "len") [x]) nil)`)
    35  
    36  func run(pass *analysis.Pass) (interface{}, error) {
    37  	fn := func(node ast.Node) {
    38  		if _, ok := code.Match(pass, checkSlicingQ, node); ok {
    39  			expr := node.(*ast.SliceExpr)
    40  			report.Report(pass, expr.High,
    41  				"should omit second index in slice, s[a:len(s)] is identical to s[a:]",
    42  				report.FilterGenerated(),
    43  				report.Fixes(edit.Fix("simplify slice expression", edit.Delete(expr.High))))
    44  		}
    45  	}
    46  	code.Preorder(pass, fn, (*ast.SliceExpr)(nil))
    47  	return nil, nil
    48  }