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

     1  package rule
     2  
     3  import (
     4  	"fmt"
     5  	"go/ast"
     6  	"reflect"
     7  
     8  	"github.com/songshiyun/revive/lint"
     9  )
    10  
    11  // FunctionLength lint.
    12  type FunctionLength struct {
    13  	maxStmt  int
    14  	maxLines int
    15  }
    16  
    17  // Apply applies the rule to given file.
    18  func (r *FunctionLength) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
    19  	if r.maxLines == 0 {
    20  		maxStmt, maxLines := r.parseArguments(arguments)
    21  		r.maxStmt = int(maxStmt)
    22  		r.maxLines = int(maxLines)
    23  	}
    24  
    25  	var failures []lint.Failure
    26  
    27  	walker := lintFuncLength{
    28  		file:     file,
    29  		maxStmt:  r.maxStmt,
    30  		maxLines: r.maxLines,
    31  		onFailure: func(failure lint.Failure) {
    32  			failures = append(failures, failure)
    33  		},
    34  	}
    35  
    36  	ast.Walk(walker, file.AST)
    37  
    38  	return failures
    39  }
    40  
    41  // Name returns the rule name.
    42  func (r *FunctionLength) Name() string {
    43  	return "function-length"
    44  }
    45  
    46  func (r *FunctionLength) parseArguments(arguments lint.Arguments) (maxStmt, maxLines int64) {
    47  	if len(arguments) != 2 {
    48  		panic(fmt.Sprintf(`invalid configuration for "function-length" rule, expected 2 arguments but got %d`, len(arguments)))
    49  	}
    50  
    51  	maxStmt, maxStmtOk := arguments[0].(int64)
    52  	if !maxStmtOk {
    53  		panic(fmt.Sprintf(`invalid configuration value for max statements in "function-length" rule; need int64 but got %T`, arguments[0]))
    54  	}
    55  	if maxStmt < 0 {
    56  		panic(fmt.Sprintf(`the configuration value for max statements in "function-length" rule cannot be negative, got %d`, maxStmt))
    57  	}
    58  
    59  	maxLines, maxLinesOk := arguments[1].(int64)
    60  	if !maxLinesOk {
    61  		panic(fmt.Sprintf(`invalid configuration value for max lines in "function-length" rule; need int64 but got %T`, arguments[1]))
    62  	}
    63  	if maxLines < 0 {
    64  		panic(fmt.Sprintf(`the configuration value for max statements in "function-length" rule cannot be negative, got %d`, maxLines))
    65  	}
    66  
    67  	return
    68  }
    69  
    70  type lintFuncLength struct {
    71  	file      *lint.File
    72  	maxStmt   int
    73  	maxLines  int
    74  	onFailure func(lint.Failure)
    75  }
    76  
    77  func (w lintFuncLength) Visit(n ast.Node) ast.Visitor {
    78  	node, ok := n.(*ast.FuncDecl)
    79  	if !ok {
    80  		return w
    81  	}
    82  
    83  	body := node.Body
    84  	if body == nil || len(node.Body.List) == 0 {
    85  		return nil
    86  	}
    87  
    88  	if w.maxStmt > 0 {
    89  		stmtCount := w.countStmts(node.Body.List)
    90  		if stmtCount > w.maxStmt {
    91  			w.onFailure(lint.Failure{
    92  				Confidence: 1,
    93  				Failure:    fmt.Sprintf("maximum number of statements per function exceeded; max %d but got %d", w.maxStmt, stmtCount),
    94  				Node:       node,
    95  			})
    96  		}
    97  	}
    98  
    99  	if w.maxLines > 0 {
   100  		lineCount := w.countLines(node.Body)
   101  		if lineCount > w.maxLines {
   102  			w.onFailure(lint.Failure{
   103  				Confidence: 1,
   104  				Failure:    fmt.Sprintf("maximum number of lines per function exceeded; max %d but got %d", w.maxLines, lineCount),
   105  				Node:       node,
   106  			})
   107  		}
   108  	}
   109  
   110  	return nil
   111  }
   112  
   113  func (w lintFuncLength) countLines(b *ast.BlockStmt) int {
   114  	return w.file.ToPosition(b.End()).Line - w.file.ToPosition(b.Pos()).Line - 1
   115  }
   116  
   117  func (w lintFuncLength) countStmts(b []ast.Stmt) int {
   118  	count := 0
   119  	for _, s := range b {
   120  		switch stmt := s.(type) {
   121  		case *ast.BlockStmt:
   122  			count += w.countStmts(stmt.List)
   123  		case *ast.IfStmt:
   124  			count += 1 + w.countBodyListStmts(stmt)
   125  			if stmt.Else != nil {
   126  				elseBody, ok := stmt.Else.(*ast.BlockStmt)
   127  				if ok {
   128  					count += w.countStmts(elseBody.List)
   129  				}
   130  			}
   131  		case *ast.ForStmt, *ast.RangeStmt,
   132  			*ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
   133  			count += 1 + w.countBodyListStmts(stmt)
   134  		case *ast.CaseClause:
   135  			count += w.countStmts(stmt.Body)
   136  		case *ast.AssignStmt:
   137  			count += 1 + w.countFuncLitStmts(stmt.Rhs[0])
   138  		case *ast.GoStmt:
   139  			count += 1 + w.countFuncLitStmts(stmt.Call.Fun)
   140  		case *ast.DeferStmt:
   141  			count += 1 + w.countFuncLitStmts(stmt.Call.Fun)
   142  		default:
   143  			count++
   144  		}
   145  	}
   146  
   147  	return count
   148  }
   149  
   150  func (w lintFuncLength) countFuncLitStmts(stmt ast.Expr) int {
   151  	if block, ok := stmt.(*ast.FuncLit); ok {
   152  		return w.countStmts(block.Body.List)
   153  	}
   154  	return 0
   155  }
   156  
   157  func (w lintFuncLength) countBodyListStmts(t interface{}) int {
   158  	i := reflect.ValueOf(t).Elem().FieldByName(`Body`).Elem().FieldByName(`List`).Interface()
   159  	return w.countStmts(i.([]ast.Stmt))
   160  }