feat(fs): add MultiFileReadFS.AttachOrReplace

Author: nedpals

errgoengine.go

@@ -38,7 +38,7 @@ func (e *ErrgoEngine) Analyze(workingPath, msg string) (*CompiledErrorTemplate,
 	// initial context data extraction
 	contextData := NewContextData(e.SharedStore, workingPath)
 	contextData.Analyzer = template.Language.AnalyzerFactory(contextData)
-	e.FS.Attach(template.Language.stubFs, 1)
+	e.FS.AttachOrReplace(template.Language.stubFs, 1)
 
 	groupNames := template.Pattern.SubexpNames()
 	for _, submatches := range template.Pattern.FindAllStringSubmatch(msg, -1) {

fs.go

@@ -15,7 +15,7 @@ func (mfs *MultiReadFileFS) LastAttachedIdx() int {
 	return len(mfs.FSs) - 1
 }
 
-func (mfs *MultiReadFileFS) Attach(fs fs.ReadFileFS, idx int) {
+func (mfs *MultiReadFileFS) AttachOrReplace(fs fs.ReadFileFS, idx int) {
 	if idx < len(mfs.FSs) && idx >= 0 {
 		if mfs.FSs[idx] == fs {
 			return
@@ -25,14 +25,29 @@ func (mfs *MultiReadFileFS) Attach(fs fs.ReadFileFS, idx int) {
 		return
 	}
 
+	mfs.Attach(fs, idx)
+}
+
+func (mfs *MultiReadFileFS) Attach(instance fs.ReadFileFS, idx int) {
+	if idx < len(mfs.FSs) && idx >= 0 {
+		if mfs.FSs[idx] == instance {
+			return
+		}
+
+		mfs.FSs = append(
+			append(append([]fs.ReadFileFS{}, mfs.FSs[:idx]...), instance),
+			mfs.FSs[idx+1:]...)
+		return
+	}
+
 	// check first if the fs is already attached
 	for _, f := range mfs.FSs {
-		if f == fs {
+		if f == instance {
 			return
 		}
 	}
 
-	mfs.FSs = append(mfs.FSs, fs)
+	mfs.FSs = append(mfs.FSs, instance)
 }
 
 func (mfs *MultiReadFileFS) Open(name string) (fs.File, error) {