output.rb: extract from generic_erb.rb

- writing to a file or stdout
- touching timestamp files
- overwriting only if changed
- colorizing

tool/lib/output.rb

@@ -0,0 +1,47 @@
+require_relative 'vpath'
+require_relative 'colorize'
+
+class Output
+  attr_reader :path, :vpath
+
+  def initialize
+    @path = @timestamp = @ifchange = @color = nil
+    @vpath = VPath.new
+  end
+
+  def def_options(opt)
+    opt.on('-o', '--output=PATH') {|v| @path = v}
+    opt.on('-t', '--timestamp[=PATH]') {|v| @timestamp = v || true}
+    opt.on('-c', '--[no-]if-change') {|v| @ifchange = v}
+    opt.on('--color') {@color = true}
+    @vpath.def_options(opt)
+  end
+
+  def write(data)
+    unless @path
+      $stdout.print data
+      return true
+    end
+    color = Colorize.new(@color)
+    unchanged = color.pass("unchanged")
+    updated = color.fail("updated")
+
+    if @ifchange and (@vpath.read(@path, "rb") == data rescue false)
+      puts "#{@path} #{unchanged}"
+      written = false
+    else
+      File.binwrite(@path, data)
+      puts "#{@path} #{updated}"
+      written = true
+    end
+    if timestamp = @timestamp
+      if timestamp == true
+        dir, base = File.split(@path)
+        timestamp = File.join(dir, ".time." + base)
+      end
+      File.binwrite(timestamp, '')
+      File.utime(nil, nil, timestamp)
+    end
+    written
+  end
+end