github.com/songshiyun/revive@v1.1.5-0.20220323112655-f8433a19b3c5/rule/increment-decrement.go (about)

     1  package rule
     2  
     3  import (
     4  	"fmt"
     5  	"go/ast"
     6  	"go/token"
     7  
     8  	"github.com/songshiyun/revive/lint"
     9  )
    10  
    11  // IncrementDecrementRule lints given else constructs.
    12  type IncrementDecrementRule struct{}
    13  
    14  // Apply applies the rule to given file.
    15  func (r *IncrementDecrementRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
    16  	var failures []lint.Failure
    17  
    18  	fileAst := file.AST
    19  	walker := lintIncrementDecrement{
    20  		file: file,
    21  		onFailure: func(failure lint.Failure) {
    22  			failures = append(failures, failure)
    23  		},
    24  	}
    25  
    26  	ast.Walk(walker, fileAst)
    27  
    28  	return failures
    29  }
    30  
    31  // Name returns the rule name.
    32  func (r *IncrementDecrementRule) Name() string {
    33  	return "increment-decrement"
    34  }
    35  
    36  type lintIncrementDecrement struct {
    37  	file      *lint.File
    38  	fileAst   *ast.File
    39  	onFailure func(lint.Failure)
    40  }
    41  
    42  func (w lintIncrementDecrement) Visit(n ast.Node) ast.Visitor {
    43  	as, ok := n.(*ast.AssignStmt)
    44  	if !ok {
    45  		return w
    46  	}
    47  	if len(as.Lhs) != 1 {
    48  		return w
    49  	}
    50  	if !isOne(as.Rhs[0]) {
    51  		return w
    52  	}
    53  	var suffix string
    54  	switch as.Tok {
    55  	case token.ADD_ASSIGN:
    56  		suffix = "++"
    57  	case token.SUB_ASSIGN:
    58  		suffix = "--"
    59  	default:
    60  		return w
    61  	}
    62  	w.onFailure(lint.Failure{
    63  		Confidence: 0.8,
    64  		Node:       as,
    65  		Category:   "unary-op",
    66  		Failure:    fmt.Sprintf("should replace %s with %s%s", w.file.Render(as), w.file.Render(as.Lhs[0]), suffix),
    67  	})
    68  	return w
    69  }
    70  
    71  func isOne(expr ast.Expr) bool {
    72  	lit, ok := expr.(*ast.BasicLit)
    73  	return ok && lit.Kind == token.INT && lit.Value == "1"
    74  }