Add basic fs.watch implementation

README.md

@@ -73,6 +73,7 @@ See [./quicktest.nosh](./quicktest.nosh) for examples.
 - [X] fs.remove
 - [X] fs.touch
 - [ ] fs.mktemp
+- [X] fs.watch
 
 - [ ] net.ping
 - [ ] net.curl

fs/module.go

@@ -23,6 +23,7 @@ var ModuleRead = starlark.NewBuiltin("fs.read", read)
 var ModuleReaddir = starlark.NewBuiltin("fs.readdir", readdir)
 var ModuleRemove = starlark.NewBuiltin("fs.remove", remove)
 var ModuleTouch = starlark.NewBuiltin("fs.touch", touch)
+var ModuleWatch = starlark.NewBuiltin("fs.watch", watch)
 var ModuleWrite = starlark.NewBuiltin("fs.write", write)
 
 var Module *starlarkstruct.Module
@@ -60,6 +61,7 @@ func init() {
 			"split_list":          starlark.NewBuiltin("fs.split_list", splitList),
 			"to_slash":            starlark.NewBuiltin("fs.to_slash", toSlash),
 			"touch":               ModuleTouch,
+			"watch":               ModuleWatch,
 			"write":               ModuleWrite,
 		},
 	}

fs/watch.go

@@ -0,0 +1,134 @@
+package fs
+
+import (
+	"fmt"
+	"log"
+
+	"go.starlark.net/starlark"
+	strlk "go.starlark.net/starlark"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+// {{{1 WatchEvent
+type WatchEvent struct {
+	/**
+	One of:
+		CHMOD
+		CREATE
+		REMOVE
+	*/
+	Operation string
+	FileEntry
+}
+
+var (
+	_ strlk.Value    = &WatchEvent{}
+	_ strlk.HasAttrs = &WatchEvent{}
+)
+
+func (we *WatchEvent) Freeze()               { /* @TODO */ }
+func (we *WatchEvent) Hash() (uint32, error) { /* @TODO */ return 0, nil }
+func (we *WatchEvent) Truth() strlk.Bool     { return true }
+func (we *WatchEvent) Type() string          { return "WatchEvent" }
+
+// func (we *WatchEvent) String() string        { return we.AbsPath }
+func (we *WatchEvent) String() string { return we.Operation + "\t" + we.AbsPath }
+
+func (we *WatchEvent) Attr(name string) (result strlk.Value, err error) {
+	switch name {
+	case "abspath":
+		return strlk.String(we.AbsPath), nil
+	case "basename":
+		return strlk.String(we.BaseName), nil
+	case "dir":
+		return strlk.String(we.Dir), nil
+	case "ext":
+		return strlk.String(we.Ext), nil
+	case "name":
+		return strlk.String(we.Name), nil
+	case "path":
+		return strlk.String(we.Path), nil
+
+	case "operation":
+		return strlk.String(we.Operation), nil
+	}
+	return starlark.None, fmt.Errorf("Unknown attr: %s", name)
+}
+
+func (we *WatchEvent) AttrNames() []string {
+	return []string{
+		"abspath",
+		"basename",
+		"dir",
+		"ext",
+		"name",
+		"path",
+
+		"operation",
+	}
+}
+
+func watch(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	var (
+		path     string
+		callback starlark.Callable
+	)
+
+	if err := starlark.UnpackArgs("watch", args, kwargs, "path", &path, "callback", &callback); err != nil {
+		return nil, err
+	}
+
+	// @TODO improve, current implementation is very basic
+	// @TODO add non-blocking option
+	// @TODO improve error handling (use error channel, don't use 'panic')
+	{
+		// Create new watcher.
+		watcher, err := fsnotify.NewWatcher()
+		if err != nil {
+			return nil, err
+		}
+		defer watcher.Close()
+
+		// Start listening for events.
+		go func() {
+			for {
+				select {
+				case event, ok := <-watcher.Events:
+					if !ok {
+						return
+					}
+
+					// populate starlark event
+					strlkEvent := &WatchEvent{
+						Operation: event.Op.String(),
+					}
+					err = strlkEvent.FileEntry.Init(event.Name)
+					if err != nil {
+						panic(err)
+					}
+
+					_, err = starlark.Call(thread, callback, starlark.Tuple{strlkEvent}, nil)
+					if err != nil {
+						panic(err)
+					}
+
+				case err, ok := <-watcher.Errors:
+					if !ok {
+						return
+					}
+					log.Println("ERROR", err)
+				}
+			}
+		}()
+
+		err = watcher.Add(path)
+		if err != nil {
+			return nil, err
+		}
+
+		<-make(chan struct{}) // @XXX
+	}
+
+	return starlark.None, nil
+}

go.mod

@@ -2,6 +2,9 @@ module github.com/Rafflesiaceae/nosh
 
 go 1.22.1
 
-require go.starlark.net v0.0.0-20240314022150-ee8ed142361c
+require (
+	github.com/fsnotify/fsnotify v1.7.0
+	go.starlark.net v0.0.0-20240314022150-ee8ed142361c
+)
 
-require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect
+require golang.org/x/sys v0.4.0 // indirect

go.sum

@@ -1,8 +1,12 @@
+github.com/fsnotify/fsnotify v1.7.0 h1:8JEhPFa5W2WU7YfeZzPNqzMP6Lwt7L2715Ggo0nosvA=
+github.com/fsnotify/fsnotify v1.7.0/go.mod h1:40Bi/Hjc2AVfZrqy+aj+yEI+/bRxZnMJyTJwOpGvigM=
 github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 go.starlark.net v0.0.0-20240314022150-ee8ed142361c h1:roAjH18hZcwI4hHStHbkXjF5b7UUyZ/0SG3hXNN1SjA=
 go.starlark.net v0.0.0-20240314022150-ee8ed142361c/go.mod h1:YKMCv9b1WrfWmeqdV5MAuEHWsu5iC+fe6kYl2sQjdI8=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.4.0 h1:Zr2JFtRQNX3BCZ8YtxRE9hNJYC8J6I1MVbMg6owUp18=
+golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
 google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=