Add --header-lines option

man/man1/fzf.1

@@ -259,8 +259,11 @@ Maximum number of entries in the history file (default: 1000). The file is
 automatically truncated when the number of the lines exceeds the value.
 .TP
 .BI "--header-file=" "FILE"
-The content of the file will be printed as the "sticky" header. The file can
+The content of the file will be printed as the sticky header. The file can
 span multiple lines and can contain ANSI color codes.
+.TP
+.BI "--header-lines=" "N"
+The first N lines of the input are treated as the sticky header.
 .SS Scripting
 .TP
 .BI "-q, --query=" "STR"

src/chunklist.go

@@ -26,8 +26,13 @@ func NewChunkList(trans ItemBuilder) *ChunkList {
 		trans:  trans}
 }
 
-func (c *Chunk) push(trans ItemBuilder, data *string, index int) {
-	*c = append(*c, trans(data, index))
+func (c *Chunk) push(trans ItemBuilder, data *string, index int) bool {
+	item := trans(data, index)
+	if item != nil {
+		*c = append(*c, item)
+		return true
+	}
+	return false
 }
 
 // IsFull returns true if the Chunk is full
@@ -48,7 +53,7 @@ func CountItems(cs []*Chunk) int {
 }
 
 // Push adds the item to the list
-func (cl *ChunkList) Push(data string) {
+func (cl *ChunkList) Push(data string) bool {
 	cl.mutex.Lock()
 	defer cl.mutex.Unlock()
 
@@ -57,8 +62,11 @@ func (cl *ChunkList) Push(data string) {
 		cl.chunks = append(cl.chunks, &newChunk)
 	}
 
-	cl.lastChunk().push(cl.trans, &data, cl.count)
+	if cl.lastChunk().push(cl.trans, &data, cl.count) {
 		cl.count++
+		return true
+	}
+	return false
 }
 
 // Snapshot returns immutable snapshot of the ChunkList

src/constants.go

@@ -44,5 +44,6 @@ const (
 	EvtSearchNew
 	EvtSearchProgress
 	EvtSearchFin
+	EvtHeader
 	EvtClose
 )

src/core.go

@@ -44,6 +44,7 @@ Reader   -> EvtReadNew        -> Matcher  (restart)
 Terminal -> EvtSearchNew:bool -> Matcher  (restart)
 Matcher  -> EvtSearchProgress -> Terminal (update info)
 Matcher  -> EvtSearchFin      -> Terminal (update list)
+Matcher  -> EvtHeader         -> Terminal (update header)
 */
 
 // Run starts fzf
@@ -83,8 +84,14 @@ func Run(opts *Options) {
 
 	// Chunk list
 	var chunkList *ChunkList
+	header := make([]string, 0, opts.HeaderLines)
 	if len(opts.WithNth) == 0 {
 		chunkList = NewChunkList(func(data *string, index int) *Item {
+			if len(header) < opts.HeaderLines {
+				header = append(header, *data)
+				eventBox.Set(EvtHeader, header)
+				return nil
+			}
 			data, colors := ansiProcessor(data)
 			return &Item{
 				text:   data,
@@ -94,6 +101,11 @@ func Run(opts *Options) {
 		})
 	} else {
 		chunkList = NewChunkList(func(data *string, index int) *Item {
+			if len(header) < opts.HeaderLines {
+				header = append(header, *data)
+				eventBox.Set(EvtHeader, header)
+				return nil
+			}
 			tokens := Tokenize(data, opts.Delimiter)
 			trans := Transform(tokens, opts.WithNth)
 			item := Item{
@@ -113,7 +125,9 @@ func Run(opts *Options) {
 	// Reader
 	streamingFilter := opts.Filter != nil && !sort && !opts.Tac && !opts.Sync
 	if !streamingFilter {
-		reader := Reader{func(str string) { chunkList.Push(str) }, eventBox, opts.ReadZero}
+		reader := Reader{func(str string) bool {
+			return chunkList.Push(str)
+		}, eventBox, opts.ReadZero}
 		go reader.ReadSource()
 	}
 
@@ -134,11 +148,12 @@ func Run(opts *Options) {
 
 		if streamingFilter {
 			reader := Reader{
-				func(str string) {
+				func(str string) bool {
 					item := chunkList.trans(&str, 0)
-					if pattern.MatchItem(item) {
+					if item != nil && pattern.MatchItem(item) {
 						fmt.Println(*item.text)
 					}
+					return false
 				}, eventBox, opts.ReadZero}
 			reader.ReadSource()
 		} else {
@@ -206,6 +221,9 @@ func Run(opts *Options) {
 						terminal.UpdateProgress(val)
 					}
 
+				case EvtHeader:
+					terminal.UpdateHeader(value.([]string), opts.HeaderLines)
+
 				case EvtSearchFin:
 					switch val := value.(type) {
 					case *Merger:

src/options.go

@@ -46,6 +46,7 @@ const usage = `usage: fzf [options]
     --history=FILE        History file
     --history-size=N      Maximum number of history entries (default: 1000)
     --header-file=FILE    The file whose content to be printed as header
+    --header-lines=N      The first N lines of the input are treated as header
 
   Scripting
     -q, --query=STR       Start the finder with the given query
@@ -125,6 +126,7 @@ type Options struct {
 	Sync        bool
 	History     *History
 	Header      []string
+	HeaderLines int
 	Version     bool
 }
 
@@ -168,6 +170,7 @@ func defaultOptions() *Options {
 		Sync:        false,
 		History:     nil,
 		Header:      make([]string, 0),
+		HeaderLines: 0,
 		Version:     false}
 }
 
@@ -724,9 +727,18 @@ func parseOptions(opts *Options, allArgs []string) {
 			setHistory(nextString(allArgs, &i, "history file path required"))
 		case "--history-size":
 			setHistoryMax(nextInt(allArgs, &i, "history max size required"))
+		case "--no-header-file":
+			opts.Header = []string{}
+		case "--no-header-lines":
+			opts.HeaderLines = 0
 		case "--header-file":
 			opts.Header = readHeaderFile(
 				nextString(allArgs, &i, "header file name required"))
+			opts.HeaderLines = 0
+		case "--header-lines":
+			opts.Header = []string{}
+			opts.HeaderLines = atoi(
+				nextString(allArgs, &i, "number of header lines required"))
 		case "--version":
 			opts.Version = true
 		default:
@@ -762,6 +774,10 @@ func parseOptions(opts *Options, allArgs []string) {
 				setHistoryMax(atoi(value))
 			} else if match, value := optString(arg, "--header-file="); match {
 				opts.Header = readHeaderFile(value)
+				opts.HeaderLines = 0
+			} else if match, value := optString(arg, "--header-lines="); match {
+				opts.Header = []string{}
+				opts.HeaderLines = atoi(value)
 			} else {
 				errorExit("unknown option: " + arg)
 			}

src/reader.go

@@ -11,7 +11,7 @@ import (
 
 // Reader reads from command or standard input
 type Reader struct {
-	pusher   func(string)
+	pusher   func(string) bool
 	eventBox *util.EventBox
 	delimNil bool
 }
@@ -43,9 +43,10 @@ func (r *Reader) feed(src io.Reader) {
 			if err == nil {
 				line = line[:len(line)-1]
 			}
-			r.pusher(line)
+			if r.pusher(line) {
 				r.eventBox.Set(EvtReadNew, nil)
 			}
+		}
 		if err != nil {
 			break
 		}

src/reader_test.go

@@ -10,7 +10,7 @@ func TestReadFromCommand(t *testing.T) {
 	strs := []string{}
 	eb := util.NewEventBox()
 	reader := Reader{
-		pusher:   func(s string) { strs = append(strs, s) },
+		pusher:   func(s string) bool { strs = append(strs, s); return true },
 		eventBox: eb}
 
 	// Check EventBox

src/terminal.go

@@ -79,6 +79,7 @@ var _runeWidths = make(map[rune]int)
 const (
 	reqPrompt util.EventType = iota
 	reqInfo
+	reqHeader
 	reqList
 	reqRefresh
 	reqRedraw
@@ -231,6 +232,22 @@ func (t *Terminal) UpdateCount(cnt int, final bool) {
 	}
 }
 
+// UpdateHeader updates the header
+func (t *Terminal) UpdateHeader(header []string, lines int) {
+	t.mutex.Lock()
+	t.header = make([]string, lines)
+	copy(t.header, header)
+	if !t.reverse {
+		reversed := make([]string, lines)
+		for idx, str := range t.header {
+			reversed[lines-idx-1] = str
+		}
+		t.header = reversed
+	}
+	t.mutex.Unlock()
+	t.reqBox.Set(reqHeader, nil)
+}
+
 // UpdateProgress updates the search progress
 func (t *Terminal) UpdateProgress(progress float32) {
 	t.mutex.Lock()
@@ -686,6 +703,8 @@ func (t *Terminal) Loop() {
 						t.printInfo()
 					case reqList:
 						t.printList()
+					case reqHeader:
+						t.printHeader()
 					case reqRefresh:
 						t.suppress = false
 					case reqRedraw: