From b712f2bb6a5c1eed5661072604e308951ef655f2 Mon Sep 17 00:00:00 2001
From: Junegunn Choi <junegunn.c@gmail.com>
Date: Thu, 16 Jan 2025 09:23:25 +0900
Subject: [PATCH] Export the current nth value as $FZF_NTH

---
 CHANGELOG.md     |  7 ++++---
 src/terminal.go  |  3 +++
 src/tokenizer.go | 28 +++++++++++++++++++++++++++-
 test/test_go.rb  | 33 ++++++++++++++++++++++++++-------
 4 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c772aa8..28d21bbf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -92,10 +92,11 @@ Also, fzf now offers "style presets" for quick customization, which can be activ
   # Dim the other parts
   ls -al | fzf --nth -1 --color nth:regular,fg:dim,current-fg:dim
 
-  # With 'change-nth'
+  # With 'change-nth'. The current nth option is exported as $FZF_NTH.
   ps -ef | fzf --reverse --header-lines 1 --header-border bottom --input-border \
-               --color nth:regular,fg:dim,current-fg:dim \
-               --nth 8.. --bind 'ctrl-n:change-nth(..|1|2|3|4|5|6|7|)'
+             --color nth:regular,fg:dim,current-fg:dim \
+             --nth 8.. --bind 'ctrl-n:change-nth(1|2|3|4|5|6|7|)' \
+             --bind 'result:transform-prompt:echo "${FZF_NTH}> "'
   ```
 - A single-character delimiter is now treated as a plain string delimiter rather than a regular expression delimiter, even if it's a regular expression meta-character.
     - This means you can just write `--delimiter '|'` instead of escaping it as `--delimiter '\|'`
diff --git a/src/terminal.go b/src/terminal.go
index 1f1e2ba0..7e7de9d6 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -1046,6 +1046,9 @@ func (t *Terminal) environImpl(forPreview bool) []string {
 	env = append(env, "FZF_PREVIEW_LABEL="+t.previewLabelOpts.label)
 	env = append(env, "FZF_BORDER_LABEL="+t.borderLabelOpts.label)
 	env = append(env, "FZF_LIST_LABEL="+t.listLabelOpts.label)
+	if len(t.nthCurrent) > 0 {
+		env = append(env, "FZF_NTH="+RangesToString(t.nthCurrent))
+	}
 	env = append(env, fmt.Sprintf("FZF_TOTAL_COUNT=%d", t.count))
 	env = append(env, fmt.Sprintf("FZF_MATCH_COUNT=%d", t.merger.Length()))
 	env = append(env, fmt.Sprintf("FZF_SELECT_COUNT=%d", len(t.selected)))
diff --git a/src/tokenizer.go b/src/tokenizer.go
index 7f4aef48..fade1d10 100644
--- a/src/tokenizer.go
+++ b/src/tokenizer.go
@@ -18,6 +18,32 @@ type Range struct {
 	end   int
 }
 
+func RangesToString(ranges []Range) string {
+	strs := []string{}
+	for _, r := range ranges {
+		s := ""
+		if r.begin == rangeEllipsis && r.end == rangeEllipsis {
+			s = ".."
+		} else if r.begin == r.end {
+			s = strconv.Itoa(r.begin)
+		} else {
+			if r.begin != rangeEllipsis {
+				s += strconv.Itoa(r.begin)
+			}
+
+			if r.begin != -1 {
+				s += ".."
+				if r.end != rangeEllipsis {
+					s += strconv.Itoa(r.end)
+				}
+			}
+		}
+		strs = append(strs, s)
+	}
+
+	return strings.Join(strs, ",")
+}
+
 // Token contains the tokenized part of the strings and its prefix length
 type Token struct {
 	text         *util.Chars
@@ -41,7 +67,7 @@ func (d Delimiter) String() string {
 }
 
 func newRange(begin int, end int) Range {
-	if begin == 1 {
+	if begin == 1 && end != 1 {
 		begin = rangeEllipsis
 	}
 	if end == -1 {
diff --git a/test/test_go.rb b/test/test_go.rb
index 2b5e0a24..f7c5b962 100755
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -3729,19 +3729,38 @@ class TestGoFZF < TestBase
       *[''] * 1000
     ]
     writelines(input)
-    tmux.send_keys %(#{FZF} -qfoo -n1 --bind 'space:change-nth:2|3|4|5|' < #{tempname}), :Enter
+    nths = '1,2..4,-1,-3..,..2'
+    tmux.send_keys %(#{FZF} -qfoo -n#{nths} --bind 'space:change-nth(2|3|4|5|),result:transform-prompt:echo "[$FZF_NTH] "' < #{tempname}), :Enter
 
-    tmux.until { |lines| assert_equal 4, lines.match_count }
+    tmux.until do |lines|
+      assert lines.any_include?("[#{nths}] foo")
+      assert_equal 4, lines.match_count
+    end
     tmux.send_keys :Space
-    tmux.until { |lines| assert_equal 3, lines.match_count }
+    tmux.until do |lines|
+      assert lines.any_include?('[2] foo')
+      assert_equal 3, lines.match_count
+    end
     tmux.send_keys :Space
-    tmux.until { |lines| assert_equal 2, lines.match_count }
+    tmux.until do |lines|
+      assert lines.any_include?('[3] foo')
+      assert_equal 2, lines.match_count
+    end
     tmux.send_keys :Space
-    tmux.until { |lines| assert_equal 1, lines.match_count }
+    tmux.until do |lines|
+      assert lines.any_include?('[4] foo')
+      assert_equal 1, lines.match_count
+    end
     tmux.send_keys :Space
-    tmux.until { |lines| assert_equal 0, lines.match_count }
+    tmux.until do |lines|
+      assert lines.any_include?('[5] foo')
+      assert_equal 0, lines.match_count
+    end
     tmux.send_keys :Space
-    tmux.until { |lines| assert_equal 4, lines.match_count }
+    tmux.until do |lines|
+      assert lines.any_include?("[#{nths}] foo")
+      assert_equal 4, lines.match_count
+    end
   end
 end