[Tags] Add a tag preview with a custom tagpreview.sh script (#1223)

* Add a tag preview with a custom `tagpreview.sh` script

* [Tags] Respect g:fzf_preview_window

Co-authored-by: Ingo Meyer <IJ_M@gmx.de>
Co-authored-by: Junegunn Choi <junegunn.c@gmail.com>

autoload/fzf/vim.vim

@@ -941,7 +941,7 @@ function! fzf#vim#tags(query, ...)
   return s:fzf('tags', {
   \ 'source':  'perl '.fzf#shellescape(s:bin.tags).' '.join(map(tagfiles, 'fzf#shellescape(fnamemodify(v:val, ":p"))')),
   \ 'sink*':   s:function('s:tags_sink'),
-  \ 'options': extend(opts, ['--nth', '1..2', '-m', '--tiebreak=begin', '--prompt', 'Tags> ', '--query', a:query])}, a:000)
+  \ 'options': extend(opts, ['--nth', '1..2', '-m', '-d', '\t', '--tiebreak=begin', '--prompt', 'Tags> ', '--query', a:query])}, a:000)
 endfunction
 
 " ------------------------------------------------------------------

bin/preview.sh

@@ -4,10 +4,16 @@ REVERSE="\x1b[7m"
 RESET="\x1b[m"
 
 if [ -z "$1" ]; then
-  echo "usage: $0 FILENAME[:LINENO][:IGNORED]"
+  echo "usage: $0 [--tag] FILENAME[:LINENO][:IGNORED]"
   exit 1
 fi
 
+if [ "$1" = --tag ]; then
+  shift
+  "$(dirname "${BASH_SOURCE[0]}")/tagpreview.sh" "$@"
+  exit $?
+fi
+
 IFS=':' read -r -a INPUT <<< "$1"
 FILE=${INPUT[0]}
 CENTER=${INPUT[1]}

bin/tagpreview.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+REVERSE="\x1b[7m"
+RESET="\x1b[m"
+
+if [ -z "$1" ]; then
+  echo "usage: $0 FILENAME:TAGFILE:EXCMD"
+  exit 1
+fi
+
+IFS=':' read -r FILE TAGFILE EXCMD <<< "$*"
+
+FILE="$(dirname "${TAGFILE}")/${FILE}"
+
+if [ ! -r "$FILE" ]; then
+  echo "File not found ${FILE}"
+  exit 1
+fi
+
+CENTER="$(vim -i NONE -u NONE -e -m -s "${FILE}" \
+              -c "set nomagic" \
+              -c "${EXCMD}" \
+              -c 'let l=line(".") | new | put =l | print | qa!')" || return
+
+START_LINE="$(( CENTER - FZF_PREVIEW_LINES / 2 ))"
+if (( START_LINE <= 0 )); then
+    START_LINE=1
+fi
+END_LINE="$(( START_LINE + FZF_PREVIEW_LINES - 1 ))"
+
+# Sometimes bat is installed as batcat.
+if command -v batcat > /dev/null; then
+  BATNAME="batcat"
+elif command -v bat > /dev/null; then
+  BATNAME="bat"
+fi
+
+if [ -z "$FZF_PREVIEW_COMMAND" ] && [ "${BATNAME:+x}" ]; then
+  ${BATNAME} --style="${BAT_STYLE:-numbers}" \
+             --color=always \
+             --pager=never \
+             --wrap=never \
+             --terminal-width="${FZF_PREVIEW_COLUMNS}" \
+             --line-range="${START_LINE}:${END_LINE}" \
+             --highlight-line="${CENTER}" \
+             "$FILE"
+  exit $?
+fi
+
+DEFAULT_COMMAND="highlight -O ansi -l {} || coderay {} || rougify {} || cat {}"
+CMD=${FZF_PREVIEW_COMMAND:-$DEFAULT_COMMAND}
+CMD=${CMD//{\}/$(printf %q "$FILE")}
+
+eval "$CMD" 2> /dev/null | awk "{ \
+    if (NR >= $START_LINE && NR <= $END_LINE) { \
+        if (NR == $CENTER) \
+            { gsub(/\x1b[[0-9;]*m/, \"&$REVERSE\"); printf(\"$REVERSE%s\n$RESET\", \$0); } \
+        else printf(\"$RESET%s\n\", \$0); \
+        } \
+    }"

plugin/fzf.vim

@@ -68,7 +68,7 @@ call s:defs([
 \'command!      -bang -nargs=+ -complete=dir Locate      call fzf#vim#locate(<q-args>, s:p(), <bang>0)',
 \'command!      -bang -nargs=* Ag                        call fzf#vim#ag(<q-args>, s:p(), <bang>0)',
 \'command!      -bang -nargs=* Rg                        call fzf#vim#grep("rg --column --line-number --no-heading --color=always --smart-case -- ".shellescape(<q-args>), 1, s:p(), <bang>0)',
-\'command!      -bang -nargs=* Tags                      call fzf#vim#tags(<q-args>, <bang>0)',
+\'command!      -bang -nargs=* Tags                      call fzf#vim#tags(<q-args>, s:p({ "placeholder": "--tag {2}:{-1}:{3}" }), <bang>0)',
 \'command!      -bang -nargs=* BTags                     call fzf#vim#buffer_tags(<q-args>, s:p({ "placeholder": "{2}:{3}" }), <bang>0)',
 \'command! -bar -bang Snippets                           call fzf#vim#snippets(<bang>0)',
 \'command! -bar -bang Commands                           call fzf#vim#commands(<bang>0)',