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revive/rule/max_control_nesting.go

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package rule
import (
"errors"
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"fmt"
"go/ast"
"github.com/mgechev/revive/lint"
)
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// MaxControlNestingRule sets restriction for maximum nesting of control structures.
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type MaxControlNestingRule struct {
max int64
}
const defaultMaxControlNesting = 5
// Apply applies the rule to given file.
func (r *MaxControlNestingRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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var failures []lint.Failure
fileAst := file.AST
walker := &lintMaxControlNesting{
onFailure: func(failure lint.Failure) {
failures = append(failures, failure)
},
max: int(r.max),
}
ast.Walk(walker, fileAst)
return failures
}
// Name returns the rule name.
func (*MaxControlNestingRule) Name() string {
return "max-control-nesting"
}
type lintMaxControlNesting struct {
max int
onFailure func(lint.Failure)
nestingLevelAcc int
lastCtrlStmt ast.Node
}
func (w *lintMaxControlNesting) Visit(n ast.Node) ast.Visitor {
if w.nestingLevelAcc > w.max { // we are visiting a node beyond the max nesting level
w.onFailure(lint.Failure{
Failure: fmt.Sprintf("control flow nesting exceeds %d", w.max),
Confidence: 1,
Node: w.lastCtrlStmt,
Category: lint.FailureCategoryComplexity,
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})
return nil // stop visiting deeper
}
switch v := n.(type) {
case *ast.IfStmt:
w.lastCtrlStmt = v
w.walkControlledBlock(v.Body) // "then" branch block
if v.Else != nil {
w.walkControlledBlock(v.Else) // "else" branch block
}
return nil // stop re-visiting nesting blocks (already visited by w.walkControlledBlock)
case *ast.ForStmt:
w.lastCtrlStmt = v
w.walkControlledBlock(v.Body)
return nil // stop re-visiting nesting blocks (already visited by w.walkControlledBlock)
case *ast.CaseClause: // switch case
w.lastCtrlStmt = v
for _, s := range v.Body { // visit each statement in the case clause
w.walkControlledBlock(s)
}
return nil // stop re-visiting nesting blocks (already visited by w.walkControlledBlock)
case *ast.CommClause: // select case
w.lastCtrlStmt = v
for _, s := range v.Body { // visit each statement in the select case clause
w.walkControlledBlock(s)
}
return nil // stop re-visiting nesting blocks (already visited by w.walkControlledBlock)
case *ast.FuncLit:
walker := &lintMaxControlNesting{
onFailure: w.onFailure,
max: w.max,
}
ast.Walk(walker, v.Body)
return nil
}
return w
}
func (w *lintMaxControlNesting) walkControlledBlock(b ast.Node) {
oldNestingLevel := w.nestingLevelAcc
w.nestingLevelAcc++
ast.Walk(w, b)
w.nestingLevelAcc = oldNestingLevel
}
// Configure validates the rule configuration, and configures the rule accordingly.
//
// Configuration implements the [lint.ConfigurableRule] interface.
func (r *MaxControlNestingRule) Configure(arguments lint.Arguments) error {
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if len(arguments) < 1 {
r.max = defaultMaxControlNesting
return nil
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}
check := checkNumberOfArguments(1, arguments, r.Name())
if check != nil {
return check
}
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maxNesting, ok := arguments[0].(int64) // Alt. non panicking version
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if !ok {
return errors.New(`invalid value passed as argument number to the "max-control-nesting" rule`)
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}
r.max = maxNesting
return nil
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}