Add --sync option

README.md

@@ -89,10 +89,12 @@ usage: fzf [options]
     -0, --exit-0          Exit immediately when there's no match
     -f, --filter=STR      Filter mode. Do not start interactive finder.
         --print-query     Print query as the first line
+        --sync            Synchronous search for multi-staged filtering
+                          (e.g. 'fzf --multi | fzf --sync')
 
   Environment variables
     FZF_DEFAULT_COMMAND   Default command to use when input is tty
-    FZF_DEFAULT_OPTS      Defaults options. (e.g. "-x -m")
+    FZF_DEFAULT_OPTS      Defaults options. (e.g. '-x -m')
 ```
 
 fzf will launch curses-based finder, read the list from STDIN, and write the

src/constants.go

@@ -5,7 +5,7 @@ import (
 )
 
 // Current version
-const Version = "0.9.2"
+const Version = "0.9.3"
 
 // fzf events
 const (

src/core.go

@@ -110,19 +110,8 @@ func Run(options *Options) {
 		}
 		pattern := patternBuilder([]rune(patternString))
 
-		looping := true
 		eventBox.Unwatch(EvtReadNew)
-		for looping {
+		eventBox.WaitFor(EvtReadFin)
-			eventBox.Wait(func(events *util.Events) {
-				for evt := range *events {
-					switch evt {
-					case EvtReadFin:
-						looping = false
-						return
-					}
-				}
-			})
-		}
 
 		snapshot, _ := chunkList.Snapshot()
 		merger, cancelled := matcher.scan(MatchRequest{
@@ -142,6 +131,12 @@ func Run(options *Options) {
 		}
 	}
 
+	// Synchronous search
+	if opts.Sync {
+		eventBox.Unwatch(EvtReadNew)
+		eventBox.WaitFor(EvtReadFin)
+	}
+
 	// Go interactive
 	go matcher.Loop()
 

src/options.go

@@ -41,10 +41,12 @@ const usage = `usage: fzf [options]
     -0, --exit-0          Exit immediately when there's no match
     -f, --filter=STR      Filter mode. Do not start interactive finder.
         --print-query     Print query as the first line
+        --sync            Synchronous search for multi-staged filtering
+                          (e.g. 'fzf --multi | fzf --sync')
 
   Environment variables
     FZF_DEFAULT_COMMAND   Default command to use when input is tty
-    FZF_DEFAULT_OPTS      Defaults options. (e.g. "-x -m")
+    FZF_DEFAULT_OPTS      Defaults options. (e.g. '-x -m')
 
 `
 
@@ -88,6 +90,7 @@ type Options struct {
 	Exit0      bool
 	Filter     *string
 	PrintQuery bool
+	Sync       bool
 	Version    bool
 }
 
@@ -111,6 +114,7 @@ func defaultOptions() *Options {
 		Exit0:      false,
 		Filter:     nil,
 		PrintQuery: false,
+		Sync:       false,
 		Version:    false}
 }
 
@@ -244,6 +248,12 @@ func parseOptions(opts *Options, allArgs []string) {
 			opts.PrintQuery = false
 		case "--prompt":
 			opts.Prompt = nextString(allArgs, &i, "prompt string required")
+		case "--sync":
+			opts.Sync = true
+		case "--no-sync":
+			opts.Sync = false
+		case "--async":
+			opts.Sync = false
 		case "--version":
 			opts.Version = true
 		default:

src/util/eventbox.go

@@ -78,3 +78,18 @@ func (b *EventBox) Unwatch(events ...EventType) {
 		b.ignore[event] = true
 	}
 }
+
+func (b *EventBox) WaitFor(event EventType) {
+	looping := true
+	for looping {
+		b.Wait(func(events *Events) {
+			for evt := range *events {
+				switch evt {
+				case event:
+					looping = false
+					return
+				}
+			}
+		})
+	}
+}