From dfc027d972b24b33356a2efa2879bfcc5668b502 Mon Sep 17 00:00:00 2001
From: kojix2 <2xijok@gmail.com>
Date: Mon, 7 Jun 2021 23:51:46 +0900
Subject: [PATCH] Accept hyphens as an output option

---
 lib/youplot/parser.rb | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/lib/youplot/parser.rb b/lib/youplot/parser.rb
index d8691e4..05c56e7 100644
--- a/lib/youplot/parser.rb
+++ b/lib/youplot/parser.rb
@@ -38,13 +38,17 @@ module YouPlot
         parser.on_tail('') # Add a blank line at the end
         parser.separator('')
         parser.on('Common options:')
-        parser.on('-O', '--pass [FILE]', 'file to output input data to [stdout]',
-                  'for inserting YouPlot in the middle of Unix pipes') do |v|
-          options[:pass] = v || $stdout
-        end
         parser.on('-o', '--output [FILE]', 'file to output plots to [stdout]',
                   'If no option is specified, plot will print to stderr') do |v|
-          options[:output] = v || $stdout
+          # uplot bar -o | foo
+          # uplot bar -o - -w 30 | foo
+          options[:output] = v.nil? || v == '-' ? $stdout : v
+        end
+        parser.on('-O', '--pass [FILE]', 'file to output input data to [stdout]',
+                  'for inserting YouPlot in the middle of Unix pipes') do |v|
+          # | uplot bar -O | foo
+          # | uplot bar -O - -w 30 | foo
+          options[:pass] = v.nil? || v == '-' ? $stdout : v
         end
         parser.on('-d', '--delimiter DELIM', String, 'use DELIM instead of [TAB] for field delimiter') do |v|
           options[:delimiter] = v