Use persistent history in the editor

This resolves issue #45.

edit/editor.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/elves/elvish/edit/tty"
 	"github.com/elves/elvish/parse"
+	"github.com/elves/elvish/store"
 )
 
 const lackEOL = "\033[7m\u23ce\033[m\n"
@@ -51,6 +52,8 @@ type Editor struct {
 	reader    *Reader
 	sigs      <-chan os.Signal
 	histories []string
+	store     *store.Store
+	cmdSeq    int
 	editorState
 }
 
@@ -62,39 +65,102 @@ type LineRead struct {
 	Err  error
 }
 
+func (h *history) jump(i int, line string) {
+	h.current = i
+	h.line = line
+}
+
 func (ed *Editor) appendHistory(line string) {
 	ed.histories = append(ed.histories, line)
+	if ed.store != nil {
+		ed.store.AddCmd(line)
+		// TODO(xiaq): Report possible error
+	}
+}
+
+func lastHistory(histories []string, upto int, prefix string) (int, string) {
+	for i := upto - 1; i >= 0; i-- {
+		if strings.HasPrefix(histories[i], prefix) {
+			return i, histories[i]
+		}
+	}
+	return -1, ""
+}
+
+func firstHistory(histories []string, from int, prefix string) (int, string) {
+	for i := from; i < len(histories); i++ {
+		if strings.HasPrefix(histories[i], prefix) {
+			return i, histories[i]
+		}
+	}
+	return -1, ""
 }
 
 func (ed *Editor) prevHistory() bool {
-	for i := ed.history.current - 1; i >= 0; i-- {
-		if strings.HasPrefix(ed.histories[i], ed.history.prefix) {
-			ed.history.current = i
-			ed.history.line = ed.histories[i]
+	if ed.history.current > 0 {
+		// Session history
+		i, line := lastHistory(ed.histories, ed.history.current, ed.history.prefix)
+		if i >= 0 {
+			ed.history.jump(i, line)
 			return true
 		}
 	}
+
+	if ed.store != nil {
+		// Persistent history
+		upto := ed.cmdSeq + min(0, ed.history.current)
+		i, line, err := ed.store.LastCmd(upto, ed.history.prefix)
+		if err == nil {
+			ed.history.jump(i-ed.cmdSeq, line)
+			return true
+		}
+	}
+	// TODO(xiaq): Errors other than ErrNoMatchingCmd should be reported
 	return false
 }
 
 func (ed *Editor) nextHistory() bool {
-	for i := ed.history.current + 1; i < len(ed.histories); i++ {
-		if strings.HasPrefix(ed.histories[i], ed.history.prefix) {
-			ed.history.current = i
-			ed.history.line = ed.histories[i]
+	if ed.store != nil {
+		// Persistent history
+		if ed.history.current < -1 {
+			from := ed.cmdSeq + ed.history.current + 1
+			i, line, err := ed.store.FirstCmd(from, ed.history.prefix)
+			if err == nil {
+				ed.history.jump(i-ed.cmdSeq, line)
 				return true
 			}
+			// TODO(xiaq): Errors other than ErrNoMatchingCmd should be reported
+		}
+	}
+
+	from := max(0, ed.history.current+1)
+	i, line := firstHistory(ed.histories, from, ed.history.prefix)
+	if i >= 0 {
+		ed.history.jump(i, line)
+		return true
 	}
 	return false
 }
 
 // NewEditor creates an Editor.
-func NewEditor(file *os.File, sigs <-chan os.Signal) *Editor {
+func NewEditor(file *os.File, sigs <-chan os.Signal, st *store.Store) *Editor {
+	seq := -1
+	if st != nil {
+		var err error
+		seq, err = st.NextCmdSeq()
+		if err != nil {
+			// TODO(xiaq): Also report the error
+			seq = -1
+		}
+	}
+
 	return &Editor{
 		file:   file,
 		writer: newWriter(file),
 		reader: NewReader(file),
 		sigs:   sigs,
+		store:  st,
+		cmdSeq: seq,
 	}
 }
 

edit/minmax.go

@@ -0,0 +1,15 @@
+package edit
+
+func min(a, b int) int {
+	if a <= b {
+		return a
+	}
+	return b
+}
+
+func max(a, b int) int {
+	if a >= b {
+		return a
+	}
+	return b
+}

main.go

@@ -22,7 +22,7 @@ const (
 	outChanLeader = "▶ "
 )
 
-func newEvaler() *eval.Evaler {
+func newEvalerAndStore() (*eval.Evaler, *store.Store) {
 	dataDir, err := store.EnsureDataDir()
 	if err != nil {
 		fmt.Fprintln(os.Stderr, "Warning: cannot create data dir ~/.elvish")
@@ -36,7 +36,7 @@ func newEvaler() *eval.Evaler {
 		}
 	}
 
-	return eval.NewEvaler(st, dataDir)
+	return eval.NewEvaler(st, dataDir), st
 }
 
 func printError(err error) {
@@ -51,7 +51,7 @@ func printError(err error) {
 
 // TODO(xiaq): Currently only the editor deals with signals.
 func interact() {
-	ev := newEvaler()
+	ev, st := newEvalerAndStore()
 	datadir, err := store.EnsureDataDir()
 	printError(err)
 	if err == nil {
@@ -76,7 +76,7 @@ func interact() {
 
 	sigch := make(chan os.Signal, sigchSize)
 
-	ed := edit.NewEditor(os.Stdin, sigch)
+	ed := edit.NewEditor(os.Stdin, sigch, st)
 
 	for {
 		cmdNum++
@@ -111,7 +111,7 @@ func interact() {
 }
 
 func script(fname string) {
-	ev := newEvaler()
+	ev, _ := newEvalerAndStore()
 	err := ev.Source(fname)
 	printError(err)
 	if err != nil {