Add HistorySearchUp and HistorySearchDown actions (#1829)

Add HistorySearchUp and HistorySearchDown actions which are similar to
HistoryUp and HistoryDown but search for the prev/next history item
whose beginning matches the currently entered text in the infobuffer
(more precisely, the text before cursor).

Also fixed the following issue: if we scrolled to an older history item
and then edit the infobuffer, this older item gets modified.
We should not edit old history entries. So in this case set HistoryNum
to the last (newly added) item and modify the last item.

internal/action/infopane.go

@@ -108,7 +108,11 @@ func (h *InfoPane) HandleEvent(event tcell.Event) {
 		if done && h.HasPrompt && !hasYN {
 			resp := string(h.LineBytes(0))
 			hist := h.History[h.PromptType]
-			hist[h.HistoryNum] = resp
+			if resp != hist[h.HistoryNum] {
+				h.HistoryNum = len(hist) - 1
+				hist[h.HistoryNum] = resp
+				h.HistorySearch = false
+			}
 			if h.EventCallback != nil {
 				h.EventCallback(resp)
 			}
@@ -155,6 +159,18 @@ func (h *InfoPane) HistoryDown() {
 	h.DownHistory(h.History[h.PromptType])
 }
 
+// HistorySearchUp fetches the previous history item beginning with the text
+// in the infobuffer before cursor
+func (h *InfoPane) HistorySearchUp() {
+	h.SearchUpHistory(h.History[h.PromptType])
+}
+
+// HistorySearchDown fetches the next history item beginning with the text
+// in the infobuffer before cursor
+func (h *InfoPane) HistorySearchDown() {
+	h.SearchDownHistory(h.History[h.PromptType])
+}
+
 // Autocomplete begins autocompletion
 func (h *InfoPane) CommandComplete() {
 	b := h.Buf
@@ -198,9 +214,11 @@ func (h *InfoPane) AbortCommand() {
 
 // InfoKeyActions contains the list of all possible key actions the infopane could execute
 var InfoKeyActions = map[string]InfoKeyAction{
-	"HistoryUp":       (*InfoPane).HistoryUp,
-	"HistoryDown":     (*InfoPane).HistoryDown,
-	"CommandComplete": (*InfoPane).CommandComplete,
-	"ExecuteCommand":  (*InfoPane).ExecuteCommand,
-	"AbortCommand":    (*InfoPane).AbortCommand,
+	"HistoryUp":         (*InfoPane).HistoryUp,
+	"HistoryDown":       (*InfoPane).HistoryDown,
+	"HistorySearchUp":   (*InfoPane).HistorySearchUp,
+	"HistorySearchDown": (*InfoPane).HistorySearchDown,
+	"CommandComplete":   (*InfoPane).CommandComplete,
+	"ExecuteCommand":    (*InfoPane).ExecuteCommand,
+	"AbortCommand":      (*InfoPane).AbortCommand,
 }

internal/info/history.go

@@ -4,8 +4,10 @@ import (
 	"encoding/gob"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/zyedidia/micro/v2/internal/config"
+	"github.com/zyedidia/micro/v2/internal/util"
 )
 
 // LoadHistory attempts to load user history from configDir/buffers/history
@@ -102,3 +104,51 @@ func (i *InfoBuf) DownHistory(history []string) {
 		i.Buffer.GetActiveCursor().GotoLoc(i.End())
 	}
 }
+
+// SearchUpHistory fetches the previous item in the history
+// beginning with the text in the infobuffer before cursor
+func (i *InfoBuf) SearchUpHistory(history []string) {
+	if i.HistoryNum > 0 && i.HasPrompt && !i.HasYN {
+		i.searchHistory(history, false)
+	}
+}
+
+// SearchDownHistory fetches the next item in the history
+// beginning with the text in the infobuffer before cursor
+func (i *InfoBuf) SearchDownHistory(history []string) {
+	if i.HistoryNum < len(history)-1 && i.HasPrompt && !i.HasYN {
+		i.searchHistory(history, true)
+	}
+}
+
+func (i *InfoBuf) searchHistory(history []string, down bool) {
+	line := string(i.LineBytes(0))
+	c := i.Buffer.GetActiveCursor()
+
+	if !i.HistorySearch || !strings.HasPrefix(line, i.HistorySearchPrefix) {
+		i.HistorySearch = true
+		i.HistorySearchPrefix = util.SliceStartStr(line, c.X)
+	}
+
+	found := -1
+	if down {
+		for j := i.HistoryNum + 1; j < len(history); j++ {
+			if strings.HasPrefix(history[j], i.HistorySearchPrefix) {
+				found = j
+				break
+			}
+		}
+	} else {
+		for j := i.HistoryNum - 1; j >= 0; j-- {
+			if strings.HasPrefix(history[j], i.HistorySearchPrefix) {
+				found = j
+				break
+			}
+		}
+	}
+	if found != -1 {
+		i.HistoryNum = found
+		i.Replace(i.Start(), i.End(), history[found])
+		c.GotoLoc(i.End())
+	}
+}

internal/info/infobuffer.go

@@ -25,6 +25,10 @@ type InfoBuf struct {
 	// It's a map of history type -> history array
 	History    map[string][]string
 	HistoryNum int
+	// HistorySearch indicates whether we are searching for history items
+	// beginning with HistorySearchPrefix
+	HistorySearch       bool
+	HistorySearchPrefix string
 
 	// Is the current message a message from the gutter
 	HasGutter bool
@@ -102,6 +106,7 @@ func (i *InfoBuf) Prompt(prompt string, msg string, ptype string, eventcb func(s
 		i.History[ptype] = append(i.History[ptype], "")
 	}
 	i.HistoryNum = len(i.History[ptype]) - 1
+	i.HistorySearch = false
 
 	i.PromptType = ptype
 	i.Msg = prompt