Make --accept-nth and --with-nth support templates

9 files changed, 158 insertions, 48 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7202d1d5..657df7bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,40 @@
 CHANGELOG
 =========
 
+0.60.0
+------
+
+- Added `--accept-nth` for choosing output fields
+  ```sh
+  ps -ef | fzf --multi --header-lines 1 | awk '{print $2}'
+  # Becomes
+  ps -ef | fzf --multi --header-lines 1 --accept-nth 2
+
+  git branch | fzf | cut -c3-
+  # Can be rewritten as
+  git branch | fzf --accept-nth -1
+  ```
+- `--accept-nth` and `--with-nth` now support a template that includes multiple field index expressions in curly braces
+  ```sh
+  echo foo,bar,baz | fzf --delimiter , --accept-nth '{1}, {3}, {2}'
+    # foo, baz, bar
+
+  echo foo,bar,baz | fzf --delimiter , --with-nth '{1},{3},{2},{1..2}'
+    # foo,baz,bar,foo,bar
+  ```
+- Added `exclude` and `exclude-multi` actions for dynamically excluding items
+  ```sh
+  seq 100 | fzf --bind 'ctrl-x:exclude'
+
+  # 'exclude-multi' will exclude the selected items or the current item
+  seq 100 | fzf --multi --bind 'ctrl-x:exclude-multi'
+  ```
+- Preview window now prints wrap indicator when wrapping is enabled
+  ```sh
+  seq 100 | xargs | fzf --wrap --preview 'echo {}' --preview-window wrap
+  ```
+- Bug fixes and improvements
+
 0.59.0
 ------
 _Release highlights: https://junegunn.github.io/fzf/releases/0.59.0/_
@@ -365,7 +399,7 @@ _Release highlights: https://junegunn.github.io/fzf/releases/0.54.0/_
 - fzf will not start the initial reader when `reload` or `reload-sync` is bound to `start` event. `fzf < /dev/null` or `: | fzf` are no longer required and extraneous `load` event will not fire due to the empty list.
   ```sh
   # Now this will work as expected. Previously, this would print an invalid header line.
-  # `fzf < /dev/null` or `: | fzf` would fix the problem, but then an extraneous 
+  # `fzf < /dev/null` or `: | fzf` would fix the problem, but then an extraneous
   # `load` event would fire and the header would be prematurely updated.
   fzf --header 'Loading ...' --header-lines 1 \
       --bind 'start:reload:sleep 1; ps -ef' \
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index 14ebb84e..1cea2d13 100644
--- a/man/man1/fzf.1
+++ b/man/man1/fzf.1
@@ -117,12 +117,33 @@ transformed lines (unlike in \fB\-\-preview\fR where fields are extracted from
 the original lines) because fzf doesn't allow searching against the hidden
 fields.
 .TP
-.BI "\-\-with\-nth=" "N[,..]"
-Transform the presentation of each line using field index expressions
+.BI "\-\-with\-nth=" "N[,..] or TEMPLATE"
+Transform the presentation of each line using the field index expressions.
+For advanced transformation, you can provide a template containing field index
+expressions in curly braces.
+
+.RS
+e.g.
+     # Single expression: drop the first field
+     echo foo bar baz | fzf --with-nth 2..
+
+     # Use template to rearrange fields
+     echo foo,bar,baz | fzf --delimiter , --with-nth '{1},{3},{2},{1..2}'
+.RE
 .TP
-.BI "\-\-accept\-nth=" "N[,..]"
+.BI "\-\-accept\-nth=" "N[,..] or TEMPLATE"
 Define which fields to print on accept. The last delimiter is stripped from the
-output.
+output. For advanced transformation, you can provide a template containing
+field index expressions in curly braces.
+
+.RS
+e.g.
+     # Single expression
+     echo foo bar baz | fzf --accept-nth 2
+
+     # Template
+     echo foo bar baz | fzf --accept-nth '1st: {1}, 2nd: {2}, 3rd: {3}'
+.RE
 .TP
 .B "+s, \-\-no\-sort"
 Do not sort the result
diff --git a/src/core.go b/src/core.go
index 08d9e868..939910b3 100644
--- a/src/core.go
+++ b/src/core.go
@@ -96,7 +96,7 @@ func Run(opts *Options) (int, error) {
 	var chunkList *ChunkList
 	var itemIndex int32
 	header := make([]string, 0, opts.HeaderLines)
-	if len(opts.WithNth) == 0 {
+	if opts.WithNth == nil {
 		chunkList = NewChunkList(cache, func(item *Item, data []byte) bool {
 			if len(header) < opts.HeaderLines {
 				header = append(header, byteString(data))
@@ -109,6 +109,7 @@ func Run(opts *Options) (int, error) {
 			return true
 		})
 	} else {
+		nthTransformer := opts.WithNth(opts.Delimiter)
 		chunkList = NewChunkList(cache, func(item *Item, data []byte) bool {
 			tokens := Tokenize(byteString(data), opts.Delimiter)
 			if opts.Ansi && opts.Theme.Colored && len(tokens) > 1 {
@@ -127,15 +128,13 @@ func Run(opts *Options) (int, error) {
 					}
 				}
 			}
-			trans := Transform(tokens, opts.WithNth)
-			transformed := JoinTokens(trans)
+			transformed := nthTransformer(tokens)
 			if len(header) < opts.HeaderLines {
 				header = append(header, transformed)
 				eventBox.Set(EvtHeader, header)
 				return false
 			}
 			item.text, item.colors = ansiProcessor(stringBytes(transformed))
-			item.text.TrimTrailingWhitespaces()
 			item.text.Index = itemIndex
 			item.origText = &data
 			itemIndex++
diff --git a/src/options.go b/src/options.go
index cad2936e..80079a4c 100644
--- a/src/options.go
+++ b/src/options.go
@@ -544,8 +544,8 @@ type Options struct {
 	Case              Case
 	Normalize         bool
 	Nth               []Range
-	WithNth           []Range
-	AcceptNth         []Range
+	WithNth           func(Delimiter) func([]Token) string
+	AcceptNth         func(Delimiter) func([]Token) string
 	Delimiter         Delimiter
 	Sort              int
 	Track             trackOption
@@ -667,8 +667,6 @@ func defaultOptions() *Options {
 		Case:         CaseSmart,
 		Normalize:    true,
 		Nth:          make([]Range, 0),
-		WithNth:      make([]Range, 0),
-		AcceptNth:    make([]Range, 0),
 		Delimiter:    Delimiter{},
 		Sort:         1000,
 		Track:        trackDisabled,
@@ -771,6 +769,62 @@ func splitNth(str string) ([]Range, error) {
 	return ranges, nil
 }
 
+func nthTransformer(str string) (func(Delimiter) func([]Token) string, error) {
+	// ^[0-9,-.]+$"
+	if match, _ := regexp.MatchString("^[0-9,-.]+$", str); match {
+		nth, err := splitNth(str)
+		if err != nil {
+			return nil, err
+		}
+		return func(Delimiter) func([]Token) string {
+			return func(tokens []Token) string {
+				return JoinTokens(Transform(tokens, nth))
+			}
+		}, nil
+	}
+
+	// {...} {...} ...
+	placeholder := regexp.MustCompile("{[0-9,-.]+}")
+	indexes := placeholder.FindAllStringIndex(str, -1)
+	if indexes == nil {
+		return nil, errors.New("template should include at least 1 placeholder: " + str)
+	}
+
+	type NthParts struct {
+		str string
+		nth []Range
+	}
+
+	parts := make([]NthParts, len(indexes))
+	idx := 0
+	for _, index := range indexes {
+		if idx < index[0] {
+			parts = append(parts, NthParts{str: str[idx:index[0]]})
+		}
+		if nth, err := splitNth(str[index[0]+1 : index[1]-1]); err == nil {
+			parts = append(parts, NthParts{nth: nth})
+		}
+		idx = index[1]
+	}
+	if idx < len(str) {
+		parts = append(parts, NthParts{str: str[idx:]})
+	}
+
+	return func(delimiter Delimiter) func([]Token) string {
+		return func(tokens []Token) string {
+			str := ""
+			for _, holder := range parts {
+				if holder.nth != nil {
+					str += StripLastDelimiter(JoinTokens(Transform(tokens, holder.nth)), delimiter)
+				} else {
+					str += holder.str
+				}
+			}
+			return str
+		}
+	}, nil
+}
+
 func delimiterRegexp(str string) Delimiter {
 	// Special handling of \t
 	str = strings.ReplaceAll(str, "\\t", "\t")
@@ -2387,7 +2441,7 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 			if err != nil {
 				return err
 			}
-			if opts.WithNth, err = splitNth(str); err != nil {
+			if opts.WithNth, err = nthTransformer(str); err != nil {
 				return err
 			}
 		case "--accept-nth":
@@ -2395,7 +2449,7 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 			if err != nil {
 				return err
 			}
-			if opts.AcceptNth, err = splitNth(str); err != nil {
+			if opts.AcceptNth, err = nthTransformer(str); err != nil {
 				return err
 			}
 		case "-s", "--sort":
diff --git a/src/terminal.go b/src/terminal.go
index 273f2650..9a4abf86 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -305,7 +305,7 @@ type Terminal struct {
 	nthAttr            tui.Attr
 	nth                []Range
 	nthCurrent         []Range
-	acceptNth          []Range
+	acceptNth          func([]Token) string
 	tabstop            int
 	margin             [4]sizeSpec
 	padding            [4]sizeSpec
@@ -919,7 +919,6 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		nthAttr:            opts.Theme.Nth.Attr,
 		nth:                opts.Nth,
 		nthCurrent:         opts.Nth,
-		acceptNth:          opts.AcceptNth,
 		tabstop:            opts.Tabstop,
 		hasStartActions:    false,
 		hasResultActions:   false,
@@ -961,6 +960,9 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		lastAction:         actStart,
 		lastFocus:          minItem.Index(),
 		numLinesCache:      make(map[int32]numLinesCacheValue)}
+	if opts.AcceptNth != nil {
+		t.acceptNth = opts.AcceptNth(t.delimiter)
+	}
 
 	// This should be called before accessing tui.Color*
 	tui.InitTheme(opts.Theme, renderer.DefaultTheme(), opts.Black, opts.InputBorderShape.Visible(), opts.HeaderBorderShape.Visible())
@@ -1570,9 +1572,11 @@ func (t *Terminal) output() bool {
 	transform := func(item *Item) string {
 		return item.AsString(t.ansi)
 	}
-	if len(t.acceptNth) > 0 {
+	if t.acceptNth != nil {
 		transform = func(item *Item) string {
-			return JoinTokens(StripLastDelimiter(Transform(Tokenize(item.AsString(t.ansi), t.delimiter), t.acceptNth), t.delimiter))
+			tokens := Tokenize(item.AsString(t.ansi), t.delimiter)
+			transformed := t.acceptNth(tokens)
+			return StripLastDelimiter(transformed, t.delimiter)
 		}
 	}
 	found := len(t.selected) > 0
diff --git a/src/tokenizer.go b/src/tokenizer.go
index 057d7405..aaddd17d 100644
--- a/src/tokenizer.go
+++ b/src/tokenizer.go
@@ -6,6 +6,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"unicode"
 
 	"github.com/junegunn/fzf/src/util"
 )
@@ -211,32 +212,18 @@ func Tokenize(text string, delimiter Delimiter) []Token {
 	return withPrefixLengths(tokens, 0)
 }
 
-// StripLastDelimiter removes the trailing delimiter and whitespaces from the
-// last token.
-func StripLastDelimiter(tokens []Token, delimiter Delimiter) []Token {
-	if len(tokens) == 0 {
-		return tokens
-	}
-
-	lastToken := tokens[len(tokens)-1]
-
-	if delimiter.str == nil && delimiter.regex == nil {
-		lastToken.text.TrimTrailingWhitespaces()
-	} else {
-		if delimiter.str != nil {
-			lastToken.text.TrimSuffix([]rune(*delimiter.str))
-		} else if delimiter.regex != nil {
-			str := lastToken.text.ToString()
-			locs := delimiter.regex.FindAllStringIndex(str, -1)
-			if len(locs) > 0 {
-				lastLoc := locs[len(locs)-1]
-				lastToken.text.SliceRight(lastLoc[0])
-			}
+// StripLastDelimiter removes the trailing delimiter and whitespaces
+func StripLastDelimiter(str string, delimiter Delimiter) string {
+	if delimiter.str != nil {
+		str = strings.TrimSuffix(str, *delimiter.str)
+	} else if delimiter.regex != nil {
+		locs := delimiter.regex.FindAllStringIndex(str, -1)
+		if len(locs) > 0 {
+			lastLoc := locs[len(locs)-1]
+			str = str[:lastLoc[0]]
 		}
-		lastToken.text.TrimTrailingWhitespaces()
 	}
-
-	return tokens
+	return strings.TrimRightFunc(str, unicode.IsSpace)
 }
 
 // JoinTokens concatenates the tokens into a single string
diff --git a/src/util/chars.go b/src/util/chars.go
index dd037caa..adde02a6 100644
--- a/src/util/chars.go
+++ b/src/util/chars.go
@@ -184,11 +184,6 @@ func (chars *Chars) TrailingWhitespaces() int {
 	return whitespaces
 }
 
-func (chars *Chars) TrimTrailingWhitespaces() {
-	whitespaces := chars.TrailingWhitespaces()
-	chars.slice = chars.slice[0 : len(chars.slice)-whitespaces]
-}
-
 func (chars *Chars) TrimSuffix(runes []rune) {
 	lastIdx := len(chars.slice)
 	firstIdx := lastIdx - len(runes)
diff --git a/test/test_core.rb b/test/test_core.rb
index 0d7f68f5..0e60b57e 100644
--- a/test/test_core.rb
+++ b/test/test_core.rb
@@ -1772,4 +1772,13 @@ class TestCore < TestInteractive
       assert_equal ['bar,bar,foo  :,:bazfoo'], File.readlines(tempname, chomp: true)
     end
   end
+
+  def test_accept_nth_template
+    tmux.send_keys %(echo "foo  ,bar,baz" | #{FZF} -d, --accept-nth '1st: {1}, 3rd: {3}, 2nd: {2}' --sync --bind start:accept > #{tempname}), :Enter
+    wait do
+      assert_path_exists tempname
+      # Last delimiter and the whitespaces are removed
+      assert_equal ['1st: foo, 3rd: baz, 2nd: bar'], File.readlines(tempname, chomp: true)
+    end
+  end
 end
diff --git a/test/test_filter.rb b/test/test_filter.rb
index dc66ec00..718c6e57 100644
--- a/test/test_filter.rb
+++ b/test/test_filter.rb
@@ -59,6 +59,13 @@ class TestFilter < TestBase
       `#{FZF} -f"^he hehe" -x -n 2.. --with-nth 2,1,1 < #{tempname}`.chomp
   end
 
+  def test_with_nth_template
+    writelines(['hello world ', 'byebye'])
+    assert_equal \
+      'hello world ',
+      `#{FZF} -f"^he he.he." -x -n 2.. --with-nth '{2} {1}. {1}.' < #{tempname}`.chomp
+  end
+
   def test_with_nth_ansi
     writelines(["\x1b[33mhello \x1b[34;1mworld\x1b[m ", 'byebye'])
     assert_equal \