Add jump and jump-accept actions for --bind

jump and jump-accept implement EasyMotion-like movement in fzf.
Suggested by @mhrebenyuk. Close #569.

3 files changed, 80 insertions, 13 deletions

diff --git a/src/constants.go b/src/constants.go
index 2e41e8be..eb9262df 100644
--- a/src/constants.go
+++ b/src/constants.go
@@ -36,6 +36,9 @@ const (
 
 	// History
 	defaultHistoryMax int = 1000
+
+	// Jump labels
+	defaultJumpLabels string = "qwertyuiopasdfghjklzxcvbnm1234567890QWERTYUIOPASDFGHJKLZXCVBNM"
 )
 
 // fzf events
diff --git a/src/options.go b/src/options.go
index ea7d717c..089b4c2f 100644
--- a/src/options.go
+++ b/src/options.go
@@ -45,6 +45,7 @@ const usage = `usage: fzf [options]
     --hscroll-off=COL     Number of screen columns to keep to the right of the
                           highlighted substring (default: 10)
     --inline-info         Display finder info inline with the query
+    --jump-labels=CHARS   Label characters for jump and jump-accept
     --prompt=STR          Input prompt (default: '> ')
     --bind=KEYBINDS       Custom key bindings. Refer to the man page.
     --history=FILE        History file
@@ -112,6 +113,7 @@ type Options struct {
 	Hscroll     bool
 	HscrollOff  int
 	InlineInfo  bool
+	JumpLabels  string
 	Prompt      string
 	Query       string
 	Select1     bool
@@ -153,6 +155,7 @@ func defaultOptions() *Options {
 		Hscroll:     true,
 		HscrollOff:  10,
 		InlineInfo:  false,
+		JumpLabels:  defaultJumpLabels,
 		Prompt:      "> ",
 		Query:       "",
 		Select1:     false,
@@ -553,6 +556,10 @@ func parseKeymap(keymap map[int]actionType, execmap map[int]string, str string)
 			keymap[key] = actForwardChar
 		case "forward-word":
 			keymap[key] = actForwardWord
+		case "jump":
+			keymap[key] = actJump
+		case "jump-accept":
+			keymap[key] = actJumpAccept
 		case "kill-line":
 			keymap[key] = actKillLine
 		case "kill-word":
@@ -804,6 +811,8 @@ func parseOptions(opts *Options, allArgs []string) {
 			opts.InlineInfo = true
 		case "--no-inline-info":
 			opts.InlineInfo = false
+		case "--jump-labels":
+			opts.JumpLabels = nextString(allArgs, &i, "label characters required")
 		case "-1", "--select-1":
 			opts.Select1 = true
 		case "+1", "--no-select-1":
@@ -891,6 +900,8 @@ func parseOptions(opts *Options, allArgs []string) {
 				opts.Tabstop = atoi(value)
 			} else if match, value := optString(arg, "--hscroll-off="); match {
 				opts.HscrollOff = atoi(value)
+			} else if match, value := optString(arg, "--jump-labels="); match {
+				opts.JumpLabels = value
 			} else {
 				errorExit("unknown option: " + arg)
 			}
@@ -908,6 +919,10 @@ func parseOptions(opts *Options, allArgs []string) {
 	if opts.Tabstop < 1 {
 		errorExit("tab stop must be a positive integer")
 	}
+
+	if len(opts.JumpLabels) == 0 {
+		errorExit("empty jump labels")
+	}
 }
 
 func postProcessOptions(opts *Options) {
diff --git a/src/terminal.go b/src/terminal.go
index 771cad78..4f611ebe 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -19,6 +19,14 @@ import (
 	"github.com/junegunn/go-runewidth"
 )
 
+type jumpMode int
+
+const (
+	jumpDisabled jumpMode = iota
+	jumpEnabled
+	jumpAcceptEnabled
+)
+
 // Terminal represents terminal input/output
 type Terminal struct {
 	initDelay  time.Duration
@@ -50,6 +58,8 @@ type Terminal struct {
 	count      int
 	progress   int
 	reading    bool
+	jumping    jumpMode
+	jumpLabels string
 	merger     *Merger
 	selected   map[int32]selectedItem
 	reqBox     *util.EventBox
@@ -88,6 +98,7 @@ const (
 	reqInfo
 	reqHeader
 	reqList
+	reqJump
 	reqRefresh
 	reqRedraw
 	reqClose
@@ -133,6 +144,8 @@ const (
 	actUp
 	actPageUp
 	actPageDown
+	actJump
+	actJumpAccept
 	actPrintQuery
 	actToggleSort
 	actPreviousHistory
@@ -235,6 +248,8 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		header0:    header,
 		ansi:       opts.Ansi,
 		reading:    true,
+		jumping:    jumpDisabled,
+		jumpLabels: opts.JumpLabels,
 		merger:     EmptyMerger,
 		selected:   make(map[int32]selectedItem),
 		reqBox:     util.NewEventBox(),
@@ -497,15 +512,25 @@ func (t *Terminal) printList() {
 		}
 		t.move(line, 0, true)
 		if i < count {
-			t.printItem(t.merger.Get(i+t.offset), i == t.cy-t.offset)
+			t.printItem(t.merger.Get(i+t.offset), i, i == t.cy-t.offset)
 		}
 	}
 }
 
-func (t *Terminal) printItem(item *Item, current bool) {
+func (t *Terminal) printItem(item *Item, i int, current bool) {
 	_, selected := t.selected[item.Index()]
+	label := " "
+	if t.jumping != jumpDisabled {
+		if i < len(t.jumpLabels) {
+			// Striped
+			current = i%2 == 0
+			label = t.jumpLabels[i : i+1]
+		}
+	} else if current {
+		label = ">"
+	}
+	C.CPrint(C.ColCursor, true, label)
 	if current {
-		C.CPrint(C.ColCursor, true, ">")
 		if selected {
 			C.CPrint(C.ColSelected, true, ">")
 		} else {
@@ -513,7 +538,6 @@ func (t *Terminal) printItem(item *Item, current bool) {
 		}
 		t.printHighlighted(item, true, C.ColCurrent, C.ColCurrentMatch, true)
 	} else {
-		C.CPrint(C.ColCursor, true, " ")
 		if selected {
 			C.CPrint(C.ColSelected, true, ">")
 		} else {
@@ -806,6 +830,11 @@ func (t *Terminal) Loop() {
 						t.printInfo()
 					case reqList:
 						t.printList()
+					case reqJump:
+						if t.merger.Length() == 0 {
+							t.jumping = jumpDisabled
+						}
+						t.printList()
 					case reqHeader:
 						t.printHeader()
 					case reqRefresh:
@@ -1025,6 +1054,12 @@ func (t *Terminal) Loop() {
 			case actPageDown:
 				t.vmove(-(t.maxItems() - 1))
 				req(reqList)
+			case actJump:
+				t.jumping = jumpEnabled
+				req(reqJump)
+			case actJumpAccept:
+				t.jumping = jumpAcceptEnabled
+				req(reqJump)
 			case actBackwardWord:
 				t.cx = findLastMatch("[^[:alnum:]][[:alnum:]]", string(t.input[:t.cx])) + 1
 			case actForwardWord:
@@ -1104,18 +1139,32 @@ func (t *Terminal) Loop() {
 			}
 			return true
 		}
-		action := t.keymap[event.Type]
+		changed := false
 		mapkey := event.Type
-		if event.Type == C.Rune {
-			mapkey = int(event.Char) + int(C.AltZ)
-			if act, prs := t.keymap[mapkey]; prs {
-				action = act
+		if t.jumping == jumpDisabled {
+			action := t.keymap[mapkey]
+			if mapkey == C.Rune {
+				mapkey = int(event.Char) + int(C.AltZ)
+				if act, prs := t.keymap[mapkey]; prs {
+					action = act
+				}
 			}
+			if !doAction(action, mapkey) {
+				continue
+			}
+			changed = string(previousInput) != string(t.input)
+		} else {
+			if mapkey == C.Rune {
+				if idx := strings.IndexRune(t.jumpLabels, event.Char); idx >= 0 {
+					t.cy = idx + t.offset
+					if t.jumping == jumpAcceptEnabled {
+						req(reqClose)
+					}
+				}
+			}
+			t.jumping = jumpDisabled
+			req(reqList)
 		}
-		if !doAction(action, mapkey) {
-			continue
-		}
-		changed := string(previousInput) != string(t.input)
 		t.mutex.Unlock() // Must be unlocked before touching reqBox
 
 		if changed {