feat: support for stub files in libraries

Author: nedpals

errgoengine.go

@@ -12,16 +12,21 @@ import (
 type ErrgoEngine struct {
 	SharedStore    *Store
 	ErrorTemplates ErrorTemplates
-	FS             fs.ReadFileFS
+	FS             *MultiReadFileFS
 	OutputGen      *OutputGenerator
 }
 
 func New() *ErrgoEngine {
+	filesystems := make([]fs.ReadFileFS, 2)
+	filesystems[0] = &RawFS{}
+
 	return &ErrgoEngine{
 		SharedStore:    NewEmptyStore(),
 		ErrorTemplates: ErrorTemplates{},
-		FS:             &RawFS{},
-		OutputGen:      &OutputGenerator{},
+		FS: &MultiReadFileFS{
+			FSs: filesystems,
+		},
+		OutputGen: &OutputGenerator{},
 	}
 }
 
@@ -34,6 +39,7 @@ 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.FSs[1] = template.Language.stubFs
 
 	groupNames := template.Pattern.SubexpNames()
 	for _, submatches := range template.Pattern.FindAllStringSubmatch(msg, -1) {
@@ -88,6 +94,11 @@ func (e *ErrgoEngine) Analyze(workingPath, msg string) (*CompiledErrorTemplate,
 			return nil, nil, err
 		}
 
+		// Skip stub files
+		if len(contents) == 0 {
+			continue
+		}
+
 		var selectedLanguage *Language
 		existingDoc, docExists := contextData.Documents[node.DocumentPath]
 

fs.go

@@ -4,8 +4,95 @@ import (
 	"io"
 	"io/fs"
 	"os"
+	"time"
 )
 
+type MultiReadFileFS struct {
+	FSs []fs.ReadFileFS
+}
+
+func (mfs *MultiReadFileFS) Open(name string) (fs.File, error) {
+	for _, fs := range mfs.FSs {
+		if fs == nil {
+			continue
+		}
+
+		if file, err := fs.Open(name); err == nil {
+			return file, nil
+		}
+	}
+	return nil, os.ErrNotExist
+}
+
+type stubFileInfo struct {
+	name string
+}
+
+func (*stubFileInfo) Name() string { return "" }
+
+func (*stubFileInfo) Size() int64 { return 0 }
+
+func (*stubFileInfo) Mode() fs.FileMode { return 0400 }
+
+func (*stubFileInfo) ModTime() time.Time { return time.Now() }
+
+func (*stubFileInfo) IsDir() bool { return false }
+
+func (*stubFileInfo) Sys() any { return nil }
+
+type StubFile struct {
+	Name string
+}
+
+func (*StubFile) Read(bt []byte) (int, error) { return 0, io.EOF }
+
+func (vf *StubFile) Stat() (fs.FileInfo, error) { return &stubFileInfo{vf.Name}, nil }
+
+func (*StubFile) Close() error { return nil }
+
+type StubFS struct {
+	Files []*StubFile
+}
+
+func (vfs *StubFS) StubFile(name string) *StubFile {
+	file := &StubFile{
+		Name: name,
+	}
+	vfs.Files = append(vfs.Files, file)
+	return file
+}
+
+func (vfs *StubFS) Open(name string) (fs.File, error) {
+	for _, file := range vfs.Files {
+		if file.Name == name {
+			return file, nil
+		}
+	}
+	return nil, os.ErrNotExist
+}
+
+func (vfs *StubFS) ReadFile(name string) ([]byte, error) {
+	for _, file := range vfs.Files {
+		if file.Name == name {
+			return make([]byte, 0), nil
+		}
+	}
+	return nil, os.ErrNotExist
+}
+
+func (mfs *MultiReadFileFS) ReadFile(name string) ([]byte, error) {
+	for _, fs := range mfs.FSs {
+		if fs == nil {
+			continue
+		}
+
+		if file, err := fs.Open(name); err == nil {
+			return io.ReadAll(file)
+		}
+	}
+	return nil, os.ErrNotExist
+}
+
 type RawFS struct{}
 
 func (*RawFS) Open(name string) (fs.File, error) {

language.go

@@ -22,6 +22,7 @@ type LanguageAnalyzer interface {
 type Language struct {
 	isCompiled        bool
 	stackTraceRegex   *regexp.Regexp
+	stubFs            *StubFS
 	Name              string
 	FilePatterns      []string
 	SitterLanguage    *sitter.Language
@@ -30,6 +31,7 @@ type Language struct {
 	SymbolsToCapture  string
 	LocationConverter func(path, pos string) Location
 	AnalyzerFactory   func(cd *ContextData) LanguageAnalyzer
+	OnGenStubFS       func(fs *StubFS)
 }
 
 func (lang *Language) MatchPath(path string) bool {
@@ -58,6 +60,11 @@ func (lang *Language) Compile() {
 		panic(fmt.Sprintf("[Language -> %s] AnalyzerFactory must not be nil", lang.Name))
 	}
 
+	if lang.stubFs == nil {
+		lang.stubFs = &StubFS{}
+		lang.OnGenStubFS(lang.stubFs)
+	}
+
 	lang.isCompiled = true
 }