feat: add Source function

gofmt/golangci.go

@@ -14,6 +14,11 @@ import (
 	"github.com/golangci/gofmt/gofmt/internal/diff"
 )
 
+type Options struct {
+	NeedSimplify bool
+	RewriteRules []RewriteRule
+}
+
 var parserModeMu sync.RWMutex
 
 type RewriteRule struct {
@@ -73,6 +78,32 @@ func RunRewrite(filename string, needSimplify bool, rewriteRules []RewriteRule)
 	return diff.Diff(oldName, src, newName, res), nil
 }
 
+func Source(filename string, src []byte, opts Options) ([]byte, error) {
+	fset := token.NewFileSet()
+
+	parserModeMu.Lock()
+	initParserMode()
+	parserModeMu.Unlock()
+
+	file, sourceAdj, indentAdj, err := parse(fset, filename, src, false)
+	if err != nil {
+		return nil, err
+	}
+
+	file, err = rewriteFileContent(fset, file, opts.RewriteRules)
+	if err != nil {
+		return nil, err
+	}
+
+	ast.SortImports(fset, file)
+
+	if opts.NeedSimplify {
+		simplify(file)
+	}
+
+	return format(fset, file, sourceAdj, indentAdj, src, printer.Config{Mode: printerMode, Tabwidth: tabWidth})
+}
+
 func rewriteFileContent(fset *token.FileSet, file *ast.File, rewriteRules []RewriteRule) (*ast.File, error) {
 	for _, rewriteRule := range rewriteRules {
 		pattern, err := parseExpression(rewriteRule.Pattern, "pattern")