Implement namespaces using slices instead of maps.

More related improvements and cleanups will be done in followup commits.

This fixes #1139.

pkg/edit/builtins.go

@@ -177,15 +177,15 @@ func wordify(fm *eval.Frame, code string) {
 	}
 }
 
-func initTTYBuiltins(app cli.App, tty cli.TTY, ns eval.Ns) {
-	ns.AddGoFns("<edit>", map[string]interface{}{
+func initTTYBuiltins(app cli.App, tty cli.TTY, nb eval.NsBuilder) {
+	nb.AddGoFns("<edit>", map[string]interface{}{
 		"-dump-buf":  func() string { return dumpBuf(tty) },
 		"insert-raw": func() { insertRaw(app, tty) },
 	})
 }
 
-func initMiscBuiltins(app cli.App, ns eval.Ns) {
-	ns.AddGoFns("<edit>", map[string]interface{}{
+func initMiscBuiltins(app cli.App, nb eval.NsBuilder) {
+	nb.AddGoFns("<edit>", map[string]interface{}{
 		"binding-table":  MakeBindingMap,
 		"close-listing":  func() { closeListing(app) },
 		"end-of-history": func() { endOfHistory(app) },
@@ -225,8 +225,8 @@ var bufferBuiltinsData = map[string]func(*cli.CodeBuffer){
 	"kill-line-right":       makeKill(moveDotEOL),
 }
 
-func initBufferBuiltins(app cli.App, ns eval.Ns) {
-	ns.AddGoFns("<edit>", bufferBuiltins(app))
+func initBufferBuiltins(app cli.App, nb eval.NsBuilder) {
+	nb.AddGoFns("<edit>", bufferBuiltins(app))
 }
 
 func bufferBuiltins(app cli.App) map[string]interface{} {

pkg/edit/builtins_test.go

@@ -96,7 +96,7 @@ func TestKey(t *testing.T) {
 
 	evals(f.Evaler, `k = (edit:key a)`)
 	wantK := ui.K('a')
-	if k := f.Evaler.Global["k"].Get(); k != wantK {
+	if k, _ := f.Evaler.Global.Index("k"); k != wantK {
 		t.Errorf("$k is %v, want %v", k, wantK)
 	}
 }
@@ -175,7 +175,7 @@ func TestWordify(t *testing.T) {
 
 	evals(f.Evaler, `@words = (edit:wordify 'ls str [list]')`)
 	wantWords := vals.MakeList("ls", "str", "[list]")
-	if words := f.Evaler.Global["words"].Get(); !vals.Equal(words, wantWords) {
+	if words, _ := f.Evaler.Global.Index("words"); !vals.Equal(words, wantWords) {
 		t.Errorf("$words is %v, want %v", words, wantWords)
 	}
 }

pkg/edit/command_api.go

@@ -9,11 +9,11 @@ import (
 //
 // Starts the command mode.
 
-func initCommandAPI(ed *Editor, ev *eval.Evaler) {
+func initCommandAPI(ed *Editor, ev *eval.Evaler, nb eval.NsBuilder) {
 	bindingVar := newBindingVar(EmptyBindingMap)
 	binding := newMapBinding(ed, ev, bindingVar)
-	ed.ns.AddNs("command",
-		eval.Ns{
+	nb.AddNs("command",
+		eval.NsBuilder{
 			"binding": bindingVar,
 		}.AddGoFns("<edit:command>:", map[string]interface{}{
 			"start": func() {
@@ -23,5 +23,5 @@ func initCommandAPI(ed *Editor, ev *eval.Evaler) {
 					Focus:   false,
 				})
 			},
-		}))
+		}).Ns())
 }

pkg/edit/completion.go

@@ -203,7 +203,7 @@ func completionStart(app cli.App, binding cli.Handler, cfg complete.Config, smar
 //
 // Closes the completion mode UI.
 
-func initCompletion(ed *Editor, ev *eval.Evaler) {
+func initCompletion(ed *Editor, ev *eval.Evaler, nb eval.NsBuilder) {
 	bindingVar := newBindingVar(EmptyBindingMap)
 	binding := newMapBinding(ed, ev, bindingVar)
 	matcherMapVar := newMapVar(vals.EmptyMap)
@@ -220,7 +220,7 @@ func initCompletion(ed *Editor, ev *eval.Evaler) {
 	generateForSudo := func(args []string) ([]complete.RawItem, error) {
 		return complete.GenerateForSudo(cfg(), args)
 	}
-	ed.ns.AddGoFns("<edit>", map[string]interface{}{
+	nb.AddGoFns("<edit>", map[string]interface{}{
 		"complete-filename": wrapArgGenerator(complete.GenerateFileNames),
 		"complete-getopt":   completeGetopt,
 		"complete-sudo":     wrapArgGenerator(generateForSudo),
@@ -230,8 +230,8 @@ func initCompletion(ed *Editor, ev *eval.Evaler) {
 		"match-substr":      wrapMatcher(strings.Contains),
 	})
 	app := ed.app
-	ed.ns.AddNs("completion",
-		eval.Ns{
+	nb.AddNs("completion",
+		eval.NsBuilder{
 			"arg-completer": argGeneratorMapVar,
 			"binding":       bindingVar,
 			"matcher":       matcherMapVar,
@@ -246,7 +246,7 @@ func initCompletion(ed *Editor, ev *eval.Evaler) {
 			"down-cycle":  func() { listingDownCycle(app) },
 			"left":        func() { listingLeft(app) },
 			"right":       func() { listingRight(app) },
-		}))
+		}).Ns())
 }
 
 // A wrapper type implementing Elvish value methods.

pkg/edit/completion_test.go

@@ -67,7 +67,7 @@ func TestComplexCandidate(t *testing.T) {
 	defer restore()
 
 	TestWithSetup(t, func(ev *eval.Evaler) {
-		ev.Global.AddGoFn("", "cc", complexCandidate)
+		ev.Global = eval.NsBuilder{}.AddGoFn("", "cc", complexCandidate).Ns()
 	},
 		That("kind-of (cc stem)").Puts("map"),
 		That("keys (cc stem)").Puts("stem", "code-suffix", "display"),

pkg/edit/config_api.go

@@ -24,25 +24,25 @@ import (
 // it can often occupy the entire terminal, and push up your scrollback buffer.
 // Change this variable to a finite number to restrict the height of the editor.
 
-func initMaxHeight(appSpec *cli.AppSpec, ns eval.Ns) {
+func initMaxHeight(appSpec *cli.AppSpec, nb eval.NsBuilder) {
 	maxHeight := newIntVar(-1)
 	appSpec.MaxHeight = func() int { return maxHeight.GetRaw().(int) }
-	ns.Add("max-height", maxHeight)
+	nb.Add("max-height", maxHeight)
 }
 
-func initReadlineHooks(appSpec *cli.AppSpec, ev *eval.Evaler, ns eval.Ns) {
-	initBeforeReadline(appSpec, ev, ns)
-	initAfterReadline(appSpec, ev, ns)
+func initReadlineHooks(appSpec *cli.AppSpec, ev *eval.Evaler, nb eval.NsBuilder) {
+	initBeforeReadline(appSpec, ev, nb)
+	initAfterReadline(appSpec, ev, nb)
 }
 
 //elvdoc:var before-readline
 //
 // A list of functions to call before each readline cycle. Each function is
 // called without any arguments.
 
-func initBeforeReadline(appSpec *cli.AppSpec, ev *eval.Evaler, ns eval.Ns) {
+func initBeforeReadline(appSpec *cli.AppSpec, ev *eval.Evaler, nb eval.NsBuilder) {
 	hook := newListVar(vals.EmptyList)
-	ns["before-readline"] = hook
+	nb["before-readline"] = hook
 	appSpec.BeforeReadline = append(appSpec.BeforeReadline, func() {
 		callHooks(ev, "$<edit>:before-readline", hook.Get().(vals.List))
 	})
@@ -53,9 +53,9 @@ func initBeforeReadline(appSpec *cli.AppSpec, ev *eval.Evaler, ns eval.Ns) {
 // A list of functions to call after each readline cycle. Each function is
 // called with a single string argument containing the code that has been read.
 
-func initAfterReadline(appSpec *cli.AppSpec, ev *eval.Evaler, ns eval.Ns) {
+func initAfterReadline(appSpec *cli.AppSpec, ev *eval.Evaler, nb eval.NsBuilder) {
 	hook := newListVar(vals.EmptyList)
-	ns["after-readline"] = hook
+	nb["after-readline"] = hook
 	appSpec.AfterReadline = append(appSpec.AfterReadline, func(code string) {
 		callHooks(ev, "$<edit>:after-readline", hook.Get().(vals.List), code)
 	})
@@ -71,11 +71,11 @@ func initAfterReadline(appSpec *cli.AppSpec, ev *eval.Evaler, ns eval.Ns) {
 // not run. The default value of this list contains a filter which
 // ignores command starts with space.
 
-func initAddCmdFilters(appSpec *cli.AppSpec, ev *eval.Evaler, ns eval.Ns, s histutil.Store) {
+func initAddCmdFilters(appSpec *cli.AppSpec, ev *eval.Evaler, nb eval.NsBuilder, s histutil.Store) {
 	ignoreLeadingSpace := eval.NewGoFn("<ignore-cmd-with-leading-space>",
 		func(s string) bool { return !strings.HasPrefix(s, " ") })
 	filters := newListVar(vals.MakeList(ignoreLeadingSpace))
-	ns["add-cmd-filters"] = filters
+	nb["add-cmd-filters"] = filters
 
 	appSpec.AfterReadline = append(appSpec.AfterReadline, func(code string) {
 		if code != "" &&

pkg/edit/editor.go

@@ -21,7 +21,7 @@ import (
 // Editor is the interface line editor for Elvish.
 type Editor struct {
 	app cli.App
-	ns  eval.Ns
+	ns  *eval.Ns
 
 	excMutex sync.RWMutex
 	excList  vals.List
@@ -39,7 +39,8 @@ type notifier interface {
 func NewEditor(tty cli.TTY, ev *eval.Evaler, st store.Store) *Editor {
 	// Declare the Editor with a nil App first; some initialization functions
 	// require a notifier as an argument, but does not use it immediately.
-	ed := &Editor{ns: eval.Ns{}, excList: vals.EmptyList}
+	ed := &Editor{excList: vals.EmptyList}
+	nb := eval.NsBuilder{}
 	appSpec := cli.AppSpec{TTY: tty}
 
 	hs, err := newHistStore(st)
@@ -48,27 +49,29 @@ func NewEditor(tty cli.TTY, ev *eval.Evaler, st store.Store) *Editor {
 	}
 
 	initHighlighter(&appSpec, ev)
-	initMaxHeight(&appSpec, ed.ns)
-	initReadlineHooks(&appSpec, ev, ed.ns)
-	initAddCmdFilters(&appSpec, ev, ed.ns, hs)
-	initInsertAPI(&appSpec, ed, ev, ed.ns)
-	initPrompts(&appSpec, ed, ev, ed.ns)
+	initMaxHeight(&appSpec, nb)
+	initReadlineHooks(&appSpec, ev, nb)
+	initAddCmdFilters(&appSpec, ev, nb, hs)
+	initInsertAPI(&appSpec, ed, ev, nb)
+	initPrompts(&appSpec, ed, ev, nb)
 	ed.app = cli.NewApp(appSpec)
 
-	initExceptionsAPI(ed)
-	initCommandAPI(ed, ev)
-	initListings(ed, ev, st, hs)
-	initNavigation(ed, ev)
-	initCompletion(ed, ev)
-	initHistWalk(ed, ev, hs)
-	initInstant(ed, ev)
-	initMinibuf(ed, ev)
-
-	initBufferBuiltins(ed.app, ed.ns)
-	initTTYBuiltins(ed.app, tty, ed.ns)
-	initMiscBuiltins(ed.app, ed.ns)
-	initStateAPI(ed.app, ed.ns)
-	initStoreAPI(ed.app, ed.ns, hs)
+	initExceptionsAPI(ed, nb)
+	initCommandAPI(ed, ev, nb)
+	initListings(ed, ev, st, hs, nb)
+	initNavigation(ed, ev, nb)
+	initCompletion(ed, ev, nb)
+	initHistWalk(ed, ev, hs, nb)
+	initInstant(ed, ev, nb)
+	initMinibuf(ed, ev, nb)
+
+	initBufferBuiltins(ed.app, nb)
+	initTTYBuiltins(ed.app, tty, nb)
+	initMiscBuiltins(ed.app, nb)
+	initStateAPI(ed.app, nb)
+	initStoreAPI(ed.app, nb, hs)
+
+	ed.ns = nb.Ns()
 	evalDefaultBinding(ev, ed.ns)
 
 	return ed
@@ -79,11 +82,11 @@ func NewEditor(tty cli.TTY, ev *eval.Evaler, st store.Store) *Editor {
 // A list of exceptions thrown from callbacks such as prompts. Useful for
 // examining tracebacks and other metadata.
 
-func initExceptionsAPI(ed *Editor) {
-	ed.ns.Add("exceptions", vars.FromPtrWithMutex(&ed.excList, &ed.excMutex))
+func initExceptionsAPI(ed *Editor, nb eval.NsBuilder) {
+	nb.Add("exceptions", vars.FromPtrWithMutex(&ed.excList, &ed.excMutex))
 }
 
-func evalDefaultBinding(ev *eval.Evaler, ns eval.Ns) {
+func evalDefaultBinding(ev *eval.Evaler, ns *eval.Ns) {
 	// TODO(xiaq): The evaler API should accodomate the use case of evaluating a
 	// piece of code in an alternative global namespace.
 
@@ -113,7 +116,7 @@ func (ed *Editor) ReadCode() (string, error) {
 }
 
 // Ns returns a namespace for manipulating the editor from Elvish code.
-func (ed *Editor) Ns() eval.Ns {
+func (ed *Editor) Ns() *eval.Ns {
 	return ed.ns
 }
 

pkg/edit/highlight.go

@@ -61,37 +61,37 @@ func hasQualifiedFn(ev *eval.Evaler, firstNs string, rest string) bool {
 	if rest == "" {
 		return false
 	}
-	modVar := ev.Global[firstNs]
-	if modVar == nil {
-		modVar = ev.Builtin[firstNs]
-		if modVar == nil {
+	modVal, ok := ev.Global.Index(firstNs)
+	if !ok {
+		modVal, ok = ev.Builtin.Index(firstNs)
+		if !ok {
 			return false
 		}
 	}
-	mod, ok := modVar.Get().(eval.Ns)
+	mod, ok := modVal.(*eval.Ns)
 	if !ok {
 		return false
 	}
 	segs := eval.SplitQNameNsSegs(rest)
 	for _, seg := range segs[:len(segs)-1] {
-		modVar = mod[seg]
-		if modVar == nil {
+		modVal, ok = mod.Index(seg)
+		if !ok {
 			return false
 		}
-		mod, ok = modVar.Get().(eval.Ns)
+		mod, ok = modVal.(*eval.Ns)
 		if !ok {
 			return false
 		}
 	}
 	return hasFn(mod, segs[len(segs)-1])
 }
 
-func hasFn(ns eval.Ns, name string) bool {
-	fnVar, ok := ns[name+eval.FnSuffix]
+func hasFn(ns *eval.Ns, name string) bool {
+	fnVar, ok := ns.Index(name + eval.FnSuffix)
 	if !ok {
 		return false
 	}
-	_, ok = fnVar.Get().(eval.Callable)
+	_, ok = fnVar.(eval.Callable)
 	return ok
 }
 

pkg/edit/highlight_test.go

@@ -40,7 +40,7 @@ func TestHighlighter(t *testing.T) {
 
 func TestCheck(t *testing.T) {
 	ev := eval.NewEvaler()
-	ev.Global.Add("good", vars.FromInit(0))
+	ev.Global = eval.NsBuilder{"good": vars.FromInit(0)}.Ns()
 
 	tt.Test(t, tt.Fn("check", check), tt.Table{
 		tt.Args(ev, mustParse("")).Rets(noError),
@@ -69,11 +69,14 @@ func TestMakeHasCommand(t *testing.T) {
 
 	// Set up global functions and modules in the evaler.
 	goodFn := eval.NewGoFn("good", func() {})
-	ev.Global.AddFn("good", goodFn)
-	aNs := eval.Ns{}.AddFn("good", goodFn)
-	bNs := eval.Ns{}.AddFn("good", goodFn)
-	aNs.AddNs("b", bNs)
-	ev.Global.AddNs("a", aNs)
+	ev.Global = eval.NsBuilder{}.
+		AddFn("good", goodFn).
+		AddNs("a",
+			eval.NsBuilder{}.
+				AddFn("good", goodFn).
+				AddNs("b", eval.NsBuilder{}.AddFn("good", goodFn).Ns()).
+				Ns()).
+		Ns()
 
 	// Set up environment.
 	testDir, cleanup := testutil.InTestDir()

pkg/edit/histwalk.go

@@ -12,12 +12,12 @@ import (
 // Import command history entries that happened after the current session
 // started.
 
-func initHistWalk(ed *Editor, ev *eval.Evaler, hs *histStore) {
+func initHistWalk(ed *Editor, ev *eval.Evaler, hs *histStore, nb eval.NsBuilder) {
 	bindingVar := newBindingVar(EmptyBindingMap)
 	binding := newMapBinding(ed, ev, bindingVar)
 	app := ed.app
-	ed.ns.AddNs("history",
-		eval.Ns{
+	nb.AddNs("history",
+		eval.NsBuilder{
 			"binding": bindingVar,
 		}.AddGoFns("<edit:history>", map[string]interface{}{
 			"start": func() { histWalkStart(app, hs, binding) },
@@ -35,7 +35,7 @@ func initHistWalk(ed *Editor, ev *eval.Evaler, hs *histStore) {
 			"close":  func() { histwalk.Close(app) },
 
 			"fast-forward": hs.FastForward,
-		}))
+		}).Ns())
 }
 
 func histWalkStart(app cli.App, hs *histStore, binding cli.Handler) {

pkg/edit/insert_api.go

@@ -102,7 +102,7 @@ import (
 //
 // @cf edit:abbr
 
-func initInsertAPI(appSpec *cli.AppSpec, nt notifier, ev *eval.Evaler, ns eval.Ns) {
+func initInsertAPI(appSpec *cli.AppSpec, nt notifier, ev *eval.Evaler, nb eval.NsBuilder) {
 	abbr := vals.EmptyMap
 	abbrVar := vars.FromPtr(&abbr)
 	appSpec.Abbreviations = makeMapIterator(abbrVar)
@@ -121,13 +121,13 @@ func initInsertAPI(appSpec *cli.AppSpec, nt notifier, ev *eval.Evaler, ns eval.N
 		quotePaste.Set(!quotePaste.Get().(bool))
 	}
 
-	ns.Add("abbr", abbrVar)
-	ns.Add("small-word-abbr", SmallWordAbbrVar)
-	ns.AddGoFn("<edit>", "toggle-quote-paste", toggleQuotePaste)
-	ns.AddNs("insert", eval.Ns{
+	nb.Add("abbr", abbrVar)
+	nb.Add("small-word-abbr", SmallWordAbbrVar)
+	nb.AddGoFn("<edit>", "toggle-quote-paste", toggleQuotePaste)
+	nb.AddNs("insert", eval.NsBuilder{
 		"binding":     binding,
 		"quote-paste": quotePaste,
-	})
+	}.Ns())
 }
 
 func makeMapIterator(mv vars.PtrVar) func(func(a, b string)) {