Add 'f' flag for placeholder expression (#1733)

If present the contents of the selection will be placed in a temporary file,
and the filename will be placed into the string instead.

src/terminal.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"os/signal"
 	"regexp"
@@ -22,9 +23,11 @@ import (
 // import "github.com/pkg/profile"
 
 var placeholder *regexp.Regexp
+var activeTempFiles []string
 
 func init() {
-	placeholder = regexp.MustCompile("\\\\?(?:{[+s]*[0-9,-.]*}|{q}|{\\+?n})")
+	placeholder = regexp.MustCompile("\\\\?(?:{[+sf]*[0-9,-.]*}|{q}|{\\+?f?nf?})")
+	activeTempFiles = []string{}
 }
 
 type jumpMode int
@@ -103,6 +106,7 @@ type Terminal struct {
 	jumping    jumpMode
 	jumpLabels string
 	printer    func(string)
+	printsep   string
 	merger     *Merger
 	selected   map[int32]selectedItem
 	version    int64
@@ -231,6 +235,7 @@ type placeholderFlags struct {
 	preserveSpace bool
 	number        bool
 	query         bool
+	file          bool
 }
 
 func toActions(types ...actionType) []action {
@@ -407,6 +412,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		jumping:    jumpDisabled,
 		jumpLabels: opts.JumpLabels,
 		printer:    opts.Printer,
+		printsep:   opts.PrintSep,
 		merger:     EmptyMerger,
 		selected:   make(map[int32]selectedItem),
 		reqBox:     util.NewEventBox(),
@@ -1207,6 +1213,9 @@ func parsePlaceholder(match string) (bool, string, placeholderFlags) {
 		case 'n':
 			flags.number = true
 			skipChars++
+		case 'f':
+			flags.file = true
+			skipChars++
 		case 'q':
 			flags.query = true
 		default:
@@ -1232,7 +1241,27 @@ func hasPreviewFlags(template string) (plus bool, query bool) {
 	return
 }
 
-func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, forcePlus bool, query string, allItems []*Item) string {
+func writeTemporaryFile(data []string, printSep string) string {
+	f, err := ioutil.TempFile("", "fzf-preview-*")
+	if err != nil {
+		errorExit("Unable to create temporary file")
+	}
+	defer f.Close()
+
+	f.WriteString(strings.Join(data, printSep))
+	f.WriteString(printSep)
+	activeTempFiles = append(activeTempFiles, f.Name())
+	return f.Name()
+}
+
+func cleanTemporaryFiles() {
+	for _, filename := range activeTempFiles {
+		os.Remove(filename)
+	}
+	activeTempFiles = []string{}
+}
+
+func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, printsep string, forcePlus bool, query string, allItems []*Item) string {
 	current := allItems[:1]
 	selected := allItems[1:]
 	if current[0] == nil {
@@ -1269,10 +1298,15 @@ func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, fo
 					} else {
 						replacements[idx] = strconv.Itoa(n)
 					}
+				} else if flags.file {
+					replacements[idx] = item.AsString(stripAnsi)
 				} else {
 					replacements[idx] = quoteEntry(item.AsString(stripAnsi))
 				}
 			}
+			if flags.file {
+				return writeTemporaryFile(replacements, printsep)
+			}
 			return strings.Join(replacements, " ")
 		}
 
@@ -1302,7 +1336,13 @@ func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, fo
 			if !flags.preserveSpace {
 				str = strings.TrimSpace(str)
 			}
-			replacements[idx] = quoteEntry(str)
+			if !flags.file {
+				str = quoteEntry(str)
+			}
+			replacements[idx] = str
+		}
+		if flags.file {
+			return writeTemporaryFile(replacements, printsep)
 		}
 		return strings.Join(replacements, " ")
 	})
@@ -1319,7 +1359,7 @@ func (t *Terminal) executeCommand(template string, forcePlus bool, background bo
 	if !valid {
 		return
 	}
-	command := replacePlaceholder(template, t.ansi, t.delimiter, forcePlus, string(t.input), list)
+	command := replacePlaceholder(template, t.ansi, t.delimiter, t.printsep, forcePlus, string(t.input), list)
 	cmd := util.ExecCommand(command, false)
 	if !background {
 		cmd.Stdin = os.Stdin
@@ -1335,6 +1375,7 @@ func (t *Terminal) executeCommand(template string, forcePlus bool, background bo
 		cmd.Run()
 		t.tui.Resume(false)
 	}
+	cleanTemporaryFiles()
 }
 
 func (t *Terminal) hasPreviewer() bool {
@@ -1492,7 +1533,7 @@ func (t *Terminal) Loop() {
 				// We don't display preview window if no match
 				if request[0] != nil {
 					command := replacePlaceholder(t.preview.command,
-						t.ansi, t.delimiter, false, string(t.input), request)
+						t.ansi, t.delimiter, t.printsep, false, string(t.input), request)
 					cmd := util.ExecCommand(command, true)
 					if t.pwindow != nil {
 						env := os.Environ()
@@ -1534,6 +1575,7 @@ func (t *Terminal) Loop() {
 					if out.Len() > 0 || !<-updateChan {
 						t.reqBox.Set(reqPreviewDisplay, out.String())
 					}
+					cleanTemporaryFiles()
 				} else {
 					t.reqBox.Set(reqPreviewDisplay, "")
 				}