Implemented the ability to forbid the usage of certain expressions

checkstyle.go

@@ -7,20 +7,22 @@ import (
 	"go/format"
 	"go/parser"
 	"go/token"
+	"reflect"
 	"strconv"
 	"strings"
 )
 
 type ProblemType string
 
 const (
-	FileLine     ProblemType = "file_line"
-	FunctionLine ProblemType = "func_line"
-	ParamsNum    ProblemType = "params_num"
-	ResultsNum   ProblemType = "results_num"
-	Formated     ProblemType = "formated"
-	PackageName  ProblemType = "pkg_name"
-	CamelName    ProblemType = "camel_name"
+	FileLine      ProblemType = "file_line"
+	FunctionLine  ProblemType = "func_line"
+	ParamsNum     ProblemType = "params_num"
+	ResultsNum    ProblemType = "results_num"
+	Formated      ProblemType = "formated"
+	PackageName   ProblemType = "pkg_name"
+	CamelName     ProblemType = "camel_name"
+	ForbiddenExpr ProblemType = "forbidden_expr"
 )
 
 type Problem struct {
@@ -36,16 +38,17 @@ type Checker interface {
 }
 
 type checker struct {
-	FunctionComment bool     `json:"func_comment"`
-	FileLine        int      `json:"file_line"`
-	FunctionLine    int      `json:"func_line"`
-	MaxIndent       int      `json:"max_indent"`
-	Formated        bool     `json:"formated"`
-	Fatal           []string `json:"fatal"`
-	ParamsNum       int      `json:"params_num"`
-	ResultsNum      int      `json:"results_num"`
-	PackageName     bool     `json:"pkg_name"`
-	CamelName       bool     `json:"camel_name"`
+	FunctionComment bool           `json:"func_comment"`
+	FileLine        int            `json:"file_line"`
+	FunctionLine    int            `json:"func_line"`
+	MaxIndent       int            `json:"max_indent"`
+	Formated        bool           `json:"formated"`
+	Fatal           []string       `json:"fatal"`
+	ParamsNum       int            `json:"params_num"`
+	ResultsNum      int            `json:"results_num"`
+	PackageName     bool           `json:"pkg_name"`
+	CamelName       bool           `json:"camel_name"`
+	ForbiddenExpr   []reflect.Type `json:"forbidden_expr"`
 }
 
 func New(config []byte) (Checker, error) {
@@ -159,6 +162,11 @@ func genFuncBodyProblem(name string, start token.Position) Problem {
 	return Problem{Description: desc, Position: &start, Type: ResultsNum}
 }
 
+func genForbExprProblem(name string, start token.Position) Problem {
+	desc := "expr " + name + " is forbidden"
+	return Problem{Description: desc, Position: &start, Type: ForbiddenExpr}
+}
+
 func (f *file) checkPkgName(pkg *ast.Ident) {
 	//ref "http://golang.org/doc/effective_go.html#package-names"
 	pkgName := pkg.Name
@@ -353,6 +361,19 @@ func (f *file) checkAssign(assign *ast.AssignStmt) {
 	}
 }
 
+func (f *file) checkForbiddenExpr(n *ast.Node, t reflect.Type) {
+	if t != nil {
+		for _, fbExpr := range f.config.ForbiddenExpr {
+			t = t.Elem()
+			if t == fbExpr {
+				pos := f.fset.Position((*n).Pos())
+				problem := genForbExprProblem(t.String(), pos)
+				f.problems = append(f.problems, problem)
+			}
+		}
+	}
+}
+
 func (f *file) checkFileContent() {
 	if f.isTest() {
 		return
@@ -380,6 +401,7 @@ func (f *file) checkFileContent() {
 				case *ast.StructType:
 					f.checkStruct(decl2)
 				}
+				f.checkForbiddenExpr(&node, reflect.TypeOf(node))
 				return true
 			})
 		case *ast.GenDecl:

checkstyle_test.go

@@ -1,6 +1,7 @@
 package checkstyle
 
 import (
+	"go/ast"
 	"go/parser"
 	"go/token"
 	"io/ioutil"
@@ -232,3 +233,34 @@ func TestCamelName(t *testing.T) {
 		t.Fatal("expect no error")
 	}
 }
+
+func TestDefer(t *testing.T) {
+	fileName := "defer.go"
+	file := readFile(fileName)
+	_checker := checker{ForbiddenExpr: []reflect.Type{}}
+	ps, err := _checker.Check(fileName, file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(ps) != 0 {
+		t.Fatal("expect no error")
+	}
+	fbExpr := []reflect.Type{reflect.TypeOf(ast.DeferStmt{})}
+	_checkerFail := checker{ForbiddenExpr: fbExpr}
+	ps, err = _checkerFail.Check(fileName, file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(ps) != 1 {
+		t.Fatal("expect 1 error but ", len(ps))
+	}
+	fileName = "no_defer.go"
+	file = readFile(fileName)
+	ps, err = _checkerFail.Check(fileName, file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(ps) != 0 {
+		t.Fatal("expect no error")
+	}
+}

testdata/defer.go

@@ -0,0 +1,9 @@
+package testdata
+
+import "fmt"
+
+func HelloWorld() {
+	defer fmt.Println("world")
+
+	fmt.Println("hello")
+}

testdata/no_defer.go

@@ -0,0 +1,8 @@
+package testdata
+
+import "fmt"
+
+func HelloWorld() {
+	fmt.Println("hello")
+	fmt.Println("world")
+}