go源文件中是否有main函数

import ( 

  "go/parser"

"go/token"

"go/ast"

) 

func HasMain(file string) (bool, error) {

fset := token.NewFileSet()

f, err := parser.ParseFile(fset, file, nil, 0)

if err != nil {

return false, err

}

for _, dec := range f.Decls {

fd, ok := dec.(*ast.FuncDecl)

if ok && fd.Name.Name == "main" {

return true, nil

}

}

return false, nil

}