From e59e42a6c235f912814ad875b1f4107a66b57ab6 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 26 May 2023 22:42:07 +0530
Subject: [PATCH] simplify API of utils.Once

---
 kittens/diff/highlight.go        |  4 ++--
 kittens/diff/mouse.go            |  4 ++--
 kittens/diff/patch.go            |  8 ++++----
 kittens/hints/marks.go           |  8 ++++----
 kittens/hyperlinked_grep/main.go |  4 ++--
 kittens/ssh/data.go              |  4 ++--
 kittens/ssh/utils.go             | 16 ++++++++--------
 tools/config/utils.go            |  8 ++++----
 tools/themes/collection.go       |  4 ++--
 tools/tui/tmux.go                |  8 ++++----
 tools/utils/hostname.go          |  4 ++--
 tools/utils/images/loading.go    |  4 ++--
 tools/utils/mimetypes.go         |  4 ++--
 tools/utils/once.go              | 10 +++++++---
 tools/utils/once_test.go         |  4 ++--
 tools/utils/paths.go             | 16 ++++++++--------
 tools/utils/which.go             |  4 ++--
 17 files changed, 59 insertions(+), 55 deletions(-)

diff --git a/kittens/diff/highlight.go b/kittens/diff/highlight.go
index 9698edcab..cd79d4fa0 100644
--- a/kittens/diff/highlight.go
+++ b/kittens/diff/highlight.go
@@ -22,7 +22,7 @@ var _ = fmt.Print
 var _ = os.WriteFile
 
 var ErrNoLexer = errors.New("No lexer available for this format")
-var DefaultStyle = (&utils.Once[*chroma.Style]{Run: func() *chroma.Style {
+var DefaultStyle = utils.Once(func() *chroma.Style {
 	// Default style generated by python style.py default pygments.styles.default.DefaultStyle
 	// with https://raw.githubusercontent.com/alecthomas/chroma/master/_tools/style.py
 	return styles.Register(chroma.MustNewStyle("default", chroma.StyleEntries{
@@ -67,7 +67,7 @@ var DefaultStyle = (&utils.Once[*chroma.Style]{Run: func() *chroma.Style {
 		chroma.Error:                 "border:#FF0000",
 		chroma.Background:            " bg:#f8f8f8",
 	}))
-}}).Get
+})
 
 // Clear the background colour.
 func clear_background(style *chroma.Style) *chroma.Style {
diff --git a/kittens/diff/mouse.go b/kittens/diff/mouse.go
index 29c269c00..f3c328674 100644
--- a/kittens/diff/mouse.go
+++ b/kittens/diff/mouse.go
@@ -42,9 +42,9 @@ func read_relevant_kitty_opts(path string) KittyOpts {
 	return ans
 }
 
-var RelevantKittyOpts = (&utils.Once[KittyOpts]{Run: func() KittyOpts {
+var RelevantKittyOpts = utils.Once(func() KittyOpts {
 	return read_relevant_kitty_opts(filepath.Join(utils.ConfigDir(), "kitty.conf"))
-}}).Get
+})
 
 func (self *Handler) handle_wheel_event(up bool) {
 	amt := RelevantKittyOpts().Wheel_scroll_multiplier
diff --git a/kittens/diff/patch.go b/kittens/diff/patch.go
index ed8cdec36..cb9e699f2 100644
--- a/kittens/diff/patch.go
+++ b/kittens/diff/patch.go
@@ -22,13 +22,13 @@ const DIFF_DIFF = `diff -p -U _CONTEXT_ --`
 
 var diff_cmd []string
 
-var GitExe = (&utils.Once[string]{Run: func() string {
+var GitExe = utils.Once(func() string {
 	return utils.FindExe("git")
-}}).Get
+})
 
-var DiffExe = (&utils.Once[string]{Run: func() string {
+var DiffExe = utils.Once(func() string {
 	return utils.FindExe("diff")
-}}).Get
+})
 
 func find_differ() {
 	if GitExe() != "git" && exec.Command(GitExe(), "--help").Run() == nil {
diff --git a/kittens/hints/marks.go b/kittens/hints/marks.go
index 72ae99eaf..eef54db47 100644
--- a/kittens/hints/marks.go
+++ b/kittens/hints/marks.go
@@ -162,7 +162,7 @@ func linenum_group_processor(gd map[string]string) {
 	gd[`path`] = utils.Expanduser(gd[`path`])
 }
 
-var PostProcessorMap = (&utils.Once[map[string]PostProcessorFunc]{Run: func() map[string]PostProcessorFunc {
+var PostProcessorMap = utils.Once(func() map[string]PostProcessorFunc {
 	return map[string]PostProcessorFunc{
 		"url": func(text string, s, e int) (int, int) {
 			if s > 4 && text[s-5:s] == "link:" { // asciidoc URLs
@@ -200,7 +200,7 @@ var PostProcessorMap = (&utils.Once[map[string]PostProcessorFunc]{Run: func() ma
 			return s, e
 		},
 	}
-}}).Get
+})
 
 type KittyOpts struct {
 	Url_prefixes              *utils.Set[string]
@@ -226,9 +226,9 @@ func read_relevant_kitty_opts(path string) KittyOpts {
 	return ans
 }
 
-var RelevantKittyOpts = (&utils.Once[KittyOpts]{Run: func() KittyOpts {
+var RelevantKittyOpts = utils.Once(func() KittyOpts {
 	return read_relevant_kitty_opts(filepath.Join(utils.ConfigDir(), "kitty.conf"))
-}}).Get
+})
 
 func functions_for(opts *Options) (pattern string, post_processors []PostProcessorFunc, group_processors []GroupProcessorFunc) {
 	switch opts.Type {
diff --git a/kittens/hyperlinked_grep/main.go b/kittens/hyperlinked_grep/main.go
index bb8d5b95d..359207560 100644
--- a/kittens/hyperlinked_grep/main.go
+++ b/kittens/hyperlinked_grep/main.go
@@ -22,9 +22,9 @@ import (
 
 var _ = fmt.Print
 
-var RgExe = (&utils.Once[string]{Run: func() string {
+var RgExe = utils.Once(func() string {
 	return utils.FindExe("rg")
-}}).Get
+})
 
 func get_options_for_rg() (expecting_args map[string]bool, alias_map map[string]string, err error) {
 	var raw []byte
diff --git a/kittens/ssh/data.go b/kittens/ssh/data.go
index 4b224f9b1..77d17f3ae 100644
--- a/kittens/ssh/data.go
+++ b/kittens/ssh/data.go
@@ -25,7 +25,7 @@ type Entry struct {
 
 type Container map[string]Entry
 
-var Data = (&utils.Once[Container]{Run: func() Container {
+var Data = utils.Once(func() Container {
 	tr := tar.NewReader(utils.ReaderForCompressedEmbeddedData(embedded_data))
 	ans := make(Container, 64)
 	for {
@@ -43,7 +43,7 @@ var Data = (&utils.Once[Container]{Run: func() Container {
 		ans[hdr.Name] = Entry{hdr, data}
 	}
 	return ans
-}}).Get
+})
 
 func (self Container) files_matching(prefix string, exclude_patterns ...string) []string {
 	ans := make([]string, 0, len(self))
diff --git a/kittens/ssh/utils.go b/kittens/ssh/utils.go
index 972417de7..358c9805a 100644
--- a/kittens/ssh/utils.go
+++ b/kittens/ssh/utils.go
@@ -17,11 +17,11 @@ import (
 
 var _ = fmt.Print
 
-var SSHExe = (&utils.Once[string]{Run: func() string {
+var SSHExe = utils.Once(func() string {
 	return utils.FindExe("ssh")
-}}).Get
+})
 
-var SSHOptions = (&utils.Once[map[string]string]{Run: func() (ssh_options map[string]string) {
+var SSHOptions = utils.Once(func() (ssh_options map[string]string) {
 	defer func() {
 		if ssh_options == nil {
 			ssh_options = map[string]string{
@@ -80,7 +80,7 @@ var SSHOptions = (&utils.Once[map[string]string]{Run: func() (ssh_options map[st
 		}
 	}
 	return
-}}).Get
+})
 
 func GetSSHCLI() (boolean_ssh_args *utils.Set[string], other_ssh_args *utils.Set[string]) {
 	other_ssh_args, boolean_ssh_args = utils.NewSet[string](32), utils.NewSet[string](32)
@@ -201,7 +201,7 @@ func (self SSHVersion) SupportsAskpassRequire() bool {
 	return self.Major > 8 || (self.Major == 8 && self.Minor >= 4)
 }
 
-var GetSSHVersion = (&utils.Once[SSHVersion]{Run: func() SSHVersion {
+var GetSSHVersion = utils.Once(func() SSHVersion {
 	b, err := exec.Command(SSHExe(), "-V").CombinedOutput()
 	if err != nil {
 		return SSHVersion{}
@@ -213,7 +213,7 @@ var GetSSHVersion = (&utils.Once[SSHVersion]{Run: func() SSHVersion {
 		return SSHVersion{Major: maj, Minor: min}
 	}
 	return SSHVersion{}
-}}).Get
+})
 
 type KittyOpts struct {
 	Term, Shell_integration string
@@ -235,6 +235,6 @@ func read_relevant_kitty_opts(path string) KittyOpts {
 	return ans
 }
 
-var RelevantKittyOpts = (&utils.Once[KittyOpts]{Run: func() KittyOpts {
+var RelevantKittyOpts = utils.Once(func() KittyOpts {
 	return read_relevant_kitty_opts(filepath.Join(utils.ConfigDir(), "kitty.conf"))
-}}).Get
+})
diff --git a/tools/config/utils.go b/tools/config/utils.go
index 9cabf8baa..dd1fc937f 100644
--- a/tools/config/utils.go
+++ b/tools/config/utils.go
@@ -189,7 +189,7 @@ func StringLiteral(val string) (string, error) {
 	return ans.String(), nil
 }
 
-var ModMap = (&utils.Once[map[string]string]{Run: func() map[string]string {
+var ModMap = utils.Once(func() map[string]string {
 	return map[string]string{
 		"shift":     "shift",
 		"⇧":         "shift",
@@ -209,11 +209,11 @@ var ModMap = (&utils.Once[map[string]string]{Run: func() map[string]string {
 		"num_lock":  "num_lock",
 		"caps_lock": "caps_lock",
 	}
-}}).Get
+})
 
-var ShortcutSpecPat = (&utils.Once[*regexp.Regexp]{Run: func() *regexp.Regexp {
+var ShortcutSpecPat = utils.Once(func() *regexp.Regexp {
 	return regexp.MustCompile(`([^+])>`)
-}}).Get
+})
 
 func NormalizeShortcut(spec string) string {
 	parts := strings.Split(strings.ToLower(spec), "+")
diff --git a/tools/themes/collection.go b/tools/themes/collection.go
index 7e7ea80d3..dc16ed28c 100644
--- a/tools/themes/collection.go
+++ b/tools/themes/collection.go
@@ -780,9 +780,9 @@ func (self *Themes) Copy() *Themes {
 	return ans
 }
 
-var camel_case_pat = (&utils.Once[*regexp.Regexp]{Run: func() *regexp.Regexp {
+var camel_case_pat = utils.Once(func() *regexp.Regexp {
 	return regexp.MustCompile(`([a-z])([A-Z])`)
-}}).Get
+})
 
 func ThemeNameFromFileName(fname string) string {
 	fname = fname[:len(fname)-len(path.Ext(fname))]
diff --git a/tools/tui/tmux.go b/tools/tui/tmux.go
index b279cf805..f3d9a21c9 100644
--- a/tools/tui/tmux.go
+++ b/tools/tui/tmux.go
@@ -20,9 +20,9 @@ import (
 
 var _ = fmt.Print
 
-var TmuxExe = (&utils.Once[string]{Run: func() string {
+var TmuxExe = utils.Once(func() string {
 	return utils.FindExe("tmux")
-}}).Get
+})
 
 func tmux_socket_address() (socket string) {
 	socket = os.Getenv("TMUX")
@@ -55,7 +55,7 @@ func tmux_socket_address() (socket string) {
 	return socket
 }
 
-var TmuxSocketAddress = (&utils.Once[string]{Run: tmux_socket_address}).Get
+var TmuxSocketAddress = utils.Once(tmux_socket_address)
 
 func tmux_command(args ...string) (c *exec.Cmd, stderr *strings.Builder) {
 	c = exec.Command(TmuxExe(), args...)
@@ -100,4 +100,4 @@ func tmux_allow_passthrough() error {
 	}
 }
 
-var TmuxAllowPassthrough = (&utils.Once[error]{Run: tmux_allow_passthrough}).Get
+var TmuxAllowPassthrough = utils.Once(tmux_allow_passthrough)
diff --git a/tools/utils/hostname.go b/tools/utils/hostname.go
index a7e81b9a0..5e1effe39 100644
--- a/tools/utils/hostname.go
+++ b/tools/utils/hostname.go
@@ -11,10 +11,10 @@ var _ = fmt.Print
 
 var hostname string = "*"
 
-var Hostname = (&Once[string]{Run: func() string {
+var Hostname = Once(func() string {
 	h, err := os.Hostname()
 	if err == nil {
 		return h
 	}
 	return ""
-}}).Get
+})
diff --git a/tools/utils/images/loading.go b/tools/utils/images/loading.go
index 229950144..9289abc67 100644
--- a/tools/utils/images/loading.go
+++ b/tools/utils/images/loading.go
@@ -264,9 +264,9 @@ func OpenNativeImageFromReader(f io.ReadSeeker) (ans *ImageData, err error) {
 	return
 }
 
-var MagickExe = (&utils.Once[string]{Run: func() string {
+var MagickExe = utils.Once(func() string {
 	return utils.FindExe("magick")
-}}).Get
+})
 
 func RunMagick(path string, cmd []string) ([]byte, error) {
 	if MagickExe() != "magick" {
diff --git a/tools/utils/mimetypes.go b/tools/utils/mimetypes.go
index d1027bcca..c742d9d65 100644
--- a/tools/utils/mimetypes.go
+++ b/tools/utils/mimetypes.go
@@ -44,7 +44,7 @@ func load_mime_file(filename string, mime_map map[string]string) error {
 	return nil
 }
 
-var UserMimeMap = (&Once[map[string]string]{Run: func() map[string]string {
+var UserMimeMap = Once(func() map[string]string {
 	conf_path := filepath.Join(ConfigDir(), "mime.types")
 	ans := make(map[string]string, 32)
 	err := load_mime_file(conf_path, ans)
@@ -52,7 +52,7 @@ var UserMimeMap = (&Once[map[string]string]{Run: func() map[string]string {
 		fmt.Fprintln(os.Stderr, "Failed to parse", conf_path, "for MIME types with error:", err)
 	}
 	return ans
-}}).Get
+})
 
 func is_rcfile(path string) bool {
 	name := filepath.Base(path)
diff --git a/tools/utils/once.go b/tools/utils/once.go
index 03734448d..822a8ab24 100644
--- a/tools/utils/once.go
+++ b/tools/utils/once.go
@@ -10,7 +10,7 @@ import (
 
 var _ = fmt.Print
 
-type Once[T any] struct {
+type once[T any] struct {
 	done       uint32
 	mutex      sync.Mutex
 	cached_val T
@@ -18,14 +18,14 @@ type Once[T any] struct {
 	Run func() T
 }
 
-func (self *Once[T]) Get() T {
+func (self *once[T]) Get() T {
 	if atomic.LoadUint32(&self.done) == 0 {
 		self.do_slow()
 	}
 	return self.cached_val
 }
 
-func (self *Once[T]) do_slow() {
+func (self *once[T]) do_slow() {
 	self.mutex.Lock()
 	defer self.mutex.Unlock()
 	if atomic.LoadUint32(&self.done) == 0 {
@@ -33,3 +33,7 @@ func (self *Once[T]) do_slow() {
 		self.cached_val = self.Run()
 	}
 }
+
+func Once[T any](f func() T) func() T {
+	return (&once[T]{Run: f}).Get
+}
diff --git a/tools/utils/once_test.go b/tools/utils/once_test.go
index c748dd16a..63518090d 100644
--- a/tools/utils/once_test.go
+++ b/tools/utils/once_test.go
@@ -11,10 +11,10 @@ var _ = fmt.Print
 
 func TestOnce(t *testing.T) {
 	num := 0
-	var G = (&Once[string]{Run: func() string {
+	var G = Once(func() string {
 		num++
 		return fmt.Sprintf("%d", num)
-	}}).Get
+	})
 	G()
 	G()
 	G()
diff --git a/tools/utils/paths.go b/tools/utils/paths.go
index d4695a61b..e70402d5e 100644
--- a/tools/utils/paths.go
+++ b/tools/utils/paths.go
@@ -62,7 +62,7 @@ func Abspath(path string) string {
 	return path
 }
 
-var KittyExe = (&Once[string]{Run: func() string {
+var KittyExe = Once(func() string {
 	exe, err := os.Executable()
 	if err == nil {
 		ans := filepath.Join(filepath.Dir(exe), "kitty")
@@ -71,7 +71,7 @@ var KittyExe = (&Once[string]{Run: func() string {
 		}
 	}
 	return os.Getenv("KITTY_PATH_TO_KITTY_EXE")
-}}).Get
+})
 
 func ConfigDirForName(name string) (config_dir string) {
 	if kcd := os.Getenv("KITTY_CONFIG_DIRECTORY"); kcd != "" {
@@ -117,11 +117,11 @@ func ConfigDirForName(name string) (config_dir string) {
 	return
 }
 
-var ConfigDir = (&Once[string]{Run: func() (config_dir string) {
+var ConfigDir = Once(func() (config_dir string) {
 	return ConfigDirForName("kitty.conf")
-}}).Get
+})
 
-var CacheDir = (&Once[string]{Run: func() (cache_dir string) {
+var CacheDir = Once(func() (cache_dir string) {
 	candidate := ""
 	if edir := os.Getenv("KITTY_CACHE_DIRECTORY"); edir != "" {
 		candidate = Abspath(Expanduser(edir))
@@ -136,7 +136,7 @@ var CacheDir = (&Once[string]{Run: func() (cache_dir string) {
 	}
 	os.MkdirAll(candidate, 0o755)
 	return candidate
-}}).Get
+})
 
 func macos_user_cache_dir() string {
 	// Sadly Go does not provide confstr() so we use this hack.
@@ -176,7 +176,7 @@ func macos_user_cache_dir() string {
 	return ""
 }
 
-var RuntimeDir = (&Once[string]{Run: func() (runtime_dir string) {
+var RuntimeDir = Once(func() (runtime_dir string) {
 	var candidate string
 	if q := os.Getenv("KITTY_RUNTIME_DIRECTORY"); q != "" {
 		candidate = q
@@ -199,7 +199,7 @@ var RuntimeDir = (&Once[string]{Run: func() (runtime_dir string) {
 		os.Chmod(candidate, 0o700)
 	}
 	return candidate
-}}).Get
+})
 
 type Walk_callback func(path, abspath string, d fs.DirEntry, err error) error
 
diff --git a/tools/utils/which.go b/tools/utils/which.go
index fcc0e7858..c5f015ffa 100644
--- a/tools/utils/which.go
+++ b/tools/utils/which.go
@@ -13,7 +13,7 @@ import (
 
 var _ = fmt.Print
 
-var DefaultExeSearchPaths = (&Once[[]string]{Run: func() []string {
+var DefaultExeSearchPaths = Once(func() []string {
 	candidates := [...]string{"/usr/local/bin", "/opt/bin", "/opt/homebrew/bin", "/usr/bin", "/bin", "/usr/sbin", "/sbin"}
 	ans := make([]string, 0, len(candidates))
 	for _, x := range candidates {
@@ -22,7 +22,7 @@ var DefaultExeSearchPaths = (&Once[[]string]{Run: func() []string {
 		}
 	}
 	return ans
-}}).Get
+})
 
 func Which(cmd string, paths ...string) string {
 	if strings.Contains(cmd, string(os.PathSeparator)) {