[preview] Clean up preview scripts

- Use preview.sh instead of preview.rb by default
- Try bat syntax highlighter with the highest priority
- Remove "-v" option as the latest version of fzf sets up $LINES
- Allow users to customize the preview command via $FZF_PREVIEW_COMMAND
  - *EXPERIMENTAL / EVOLVING / UNDOCUMENTED*
  - Should be a command template with {} placeholder expression
    - e.g. "nl {}"

README.md

@@ -185,10 +185,10 @@ command! -bang Colors
 " Augmenting Ag command using fzf#vim#with_preview function
 "   * fzf#vim#with_preview([[options], preview window, [toggle keys...]])
 "     * For syntax-highlighting, Ruby and any of the following tools are required:
+"       - Bat: https://github.com/sharkdp/bat
 "       - Highlight: http://www.andre-simon.de/doku/highlight/en/highlight.php
 "       - CodeRay: http://coderay.rubychan.de/
 "       - Rouge: https://github.com/jneen/rouge
-"       - Bat: https://github.com/sharkdp/bat
 "
 "   :Ag  - Start fzf with hidden preview window that can be enabled with "?" key
 "   :Ag! - Start fzf in fullscreen and display the preview window above

autoload/fzf/vim.vim

@@ -32,7 +32,7 @@ let s:is_win = has('win32') || has('win64')
 let s:layout_keys = ['window', 'up', 'down', 'left', 'right']
 let s:bin_dir = expand('<sfile>:h:h:h').'/bin/'
 let s:bin = {
-\ 'preview': s:bin_dir.(executable('ruby') ? 'preview.rb' : 'preview.sh'),
+\ 'preview': s:bin_dir.'preview.sh',
 \ 'tags':    s:bin_dir.'tags.pl' }
 let s:TYPE = {'dict': type({}), 'funcref': type(function('call')), 'string': type(''), 'list': type([])}
 if s:is_win

bin/preview.rb

@@ -1,18 +1,20 @@
 #!/usr/bin/env ruby
 #
-# usage: ./preview.rb [-v] FILENAME[:LINE][:IGNORED]
+# usage: ./preview.rb FILENAME[:LINE][:IGNORED]
 
+require 'open3'
 require 'shellwords'
 
-COMMAND = %[(highlight -O ansi -l {} || coderay {} || rougify {} || bat --style=numbers --color=always {} || cat {}) 2> /dev/null]
+COMMAND = ENV.fetch(
+  'FZF_PREVIEW_COMMAND',
+  %[bat --style=numbers --color=always {} || highlight -O ansi -l {} || coderay {} || rougify {} || cat {}]
+)
 ANSI    = /\x1b\[[0-9;]*m/
 REVERSE = "\x1b[7m"
 RESET   = "\x1b[m"
 
-split = ARGV.delete('-v')
-
 def usage
-  puts "usage: #$0 [-v] FILENAME[:LINENO][:IGNORED]"
+  puts "usage: #$0 FILENAME[:LINENO][:IGNORED]"
   exit 1
 end
 
@@ -37,17 +39,16 @@ if `file --mime "#{file}"` =~ /binary/
 end
 
 center = (center || 0).to_i
-if ENV['LINES']
-  height = ENV['LINES'].to_i
-else
-  height = File.readable?('/dev/tty') ? `stty size < /dev/tty`.split.first.to_i : 40
-  height /= 2 if split
-  height -= 2 # preview border
-end
+height =
+  if ENV['LINES']
+    ENV['LINES'].to_i
+  else
+    File.readable?('/dev/tty') ? `stty size < /dev/tty`.split.first.to_i : 40
+  end
 offset = [1, center - height / 3].max
 
-IO.popen(['sh', '-c', COMMAND.gsub('{}', Shellwords.shellescape(path))]) do |io|
-  io.each_line.drop(offset - 1).take(height).each_with_index do |line, lno|
+Open3.popen3(COMMAND.gsub('{}', Shellwords.shellescape(path))) do |_in, out, _err|
+  out.each_line.drop(offset - 1).take(height).each_with_index do |line, lno|
     if lno + offset == center
       puts REVERSE + line.chomp.gsub(ANSI) { |m| m + REVERSE } + RESET
     else

bin/preview.sh

@@ -3,13 +3,8 @@
 REVERSE="\x1b[7m"
 RESET="\x1b[m"
 
-if [ "$1" == "-v" ]; then
-  SPLIT=1
-  shift
-fi
-
 if [ -z "$1" ]; then
-  echo "usage: $0 [-v] FILENAME[:LINENO][:IGNORED]"
+  echo "usage: $0 FILENAME[:LINENO][:IGNORED]"
   exit 1
 fi
 
@@ -33,7 +28,7 @@ if [[ "$(file --mime "$FILE")" =~ binary ]]; then
 fi
 
 if [ -z "$CENTER" ]; then
-  CENTER=1
+  CENTER=0
 fi
 
 if [ -z "$LINES" ]; then
@@ -42,26 +37,18 @@ if [ -z "$LINES" ]; then
   else
     LINES=40
   fi
-  if [ -n "$SPLIT" ]; then
-    LINES=$(($LINES/2)) # using horizontal split
-  fi
-  LINES=$(($LINES-2)) # remove preview border
 fi
 
 FIRST=$(($CENTER-$LINES/3))
 FIRST=$(($FIRST < 1 ? 1 : $FIRST))
 LAST=$((${FIRST}+${LINES}-1))
 
-if which bat >/dev/null; then
-  CAT="bat --style=numbers --color=always"
-  $CAT $FILE | awk "NR >= $FIRST && NR <= $LAST { \
-      if (NR == $CENTER) \
-          { gsub(/\x1b[[0-9;]*m/, \"&$REVERSE\"); printf(\"$REVERSE%s\n$RESET\", \$0); } \
-      else printf(\"$RESET%s\n\", \$0); \
-      }"
-else
-  awk "NR >= $FIRST && NR <= $LAST { \
-      if (NR == $CENTER) printf(\"$REVERSE%5d %s\n$RESET\", NR, \$0); \
-      else printf(\"%5d %s\n\", NR, \$0); \
-      }" $FILE
-fi
+DEFAULT_COMMAND="bat --style=numbers --color=always {} || highlight -O ansi -l {} || coderay {} || rougify {} || cat {}"
+CMD=${FZF_PREVIEW_COMMAND:-$DEFAULT_COMMAND}
+CMD=${CMD//{\}/$(printf %q "$FILE")}
+
+eval "$CMD" 2> /dev/null | awk "NR >= $FIRST && NR <= $LAST { \
+    if (NR == $CENTER) \
+        { gsub(/\x1b[[0-9;]*m/, \"&$REVERSE\"); printf(\"$REVERSE%s\n$RESET\", \$0); } \
+    else printf(\"$RESET%s\n\", \$0); \
+    }"