Add bin and edit workflow

bin/gems/pry-0.15.2/lib/pry/pager.rb

@@ -0,0 +1,249 @@
+# frozen_string_literal: true
+
+# A pager is an `IO`-like object that accepts text and either prints it
+# immediately, prints it one page at a time, or streams it to an external
+# program to print one page at a time.
+class Pry
+  class Pager
+    class StopPaging < StandardError
+    end
+
+    attr_reader :pry_instance
+
+    def initialize(pry_instance)
+      @pry_instance = pry_instance
+    end
+
+    # Send the given text through the best available pager (if
+    # `Pry.config.pager` is enabled). If you want to send text through in
+    # chunks as you generate it, use `open` to get a writable object
+    # instead.
+    #
+    # @param [String] text
+    #   Text to run through a pager.
+    #
+    def page(text)
+      open do |pager|
+        pager << text
+      end
+    end
+
+    # Yields a pager object (`NullPager`, `SimplePager`, or `SystemPager`).
+    # All pagers accept output with `#puts`, `#print`, `#write`, and `#<<`.
+    def open
+      pager = best_available
+      yield pager
+    rescue StopPaging # rubocop:disable Lint/HandleExceptions
+    ensure
+      pager.close if pager
+    end
+
+    private
+
+    def enabled?
+      !!@enabled
+    end
+
+    attr_reader :output
+
+    # Return an instance of the "best" available pager class --
+    # `SystemPager` if possible, `SimplePager` if `SystemPager` isn't
+    # available, and `NullPager` if the user has disabled paging. All
+    # pagers accept output with `#puts`, `#print`, `#write`, and `#<<`. You
+    # must call `#close` when you're done writing output to a pager, and
+    # you must rescue `Pry::Pager::StopPaging`. These requirements can be
+    # avoided by using `.open` instead.
+    def best_available
+      if !pry_instance.config.pager
+        NullPager.new(pry_instance.output)
+      elsif !SystemPager.available? || Helpers::Platform.jruby?
+        SimplePager.new(pry_instance.output)
+      else
+        SystemPager.new(pry_instance.output)
+      end
+    end
+
+    # `NullPager` is a "pager" that actually just prints all output as it
+    # comes in. Used when `Pry.config.pager` is false.
+    class NullPager
+      def initialize(out)
+        @out = out
+      end
+
+      def puts(str)
+        print "#{str.chomp}\n"
+      end
+
+      def print(str)
+        write str
+      end
+      alias << print
+
+      def write(str)
+        @out.write str
+      end
+
+      def close; end
+
+      private
+
+      def height
+        @height ||= @out.height
+      end
+
+      def width
+        @width ||= @out.width
+      end
+    end
+
+    # `SimplePager` is a straightforward pure-Ruby pager. We use it on
+    # JRuby and when we can't find a usable external pager.
+    class SimplePager < NullPager
+      def initialize(*)
+        super
+        @tracker = PageTracker.new(height - 3, width)
+      end
+
+      def write(str)
+        str.lines.each do |line|
+          @out.print line
+          @tracker.record line
+
+          next unless @tracker.page?
+
+          @out.print "\n"
+          @out.print "\e[0m"
+          @out.print "<page break> --- Press enter to continue " \
+                     "( q<enter> to break ) --- <page break>\n"
+          raise StopPaging if Readline.readline("").chomp == "q"
+
+          @tracker.reset
+        end
+      end
+    end
+
+    # `SystemPager` buffers output until we're pretty sure it's at least a
+    # page long, then invokes an external pager and starts streaming output
+    # to it. If `#close` is called before then, it just prints out the
+    # buffered content.
+    class SystemPager < NullPager
+      def self.default_pager
+        pager = Pry::Env['PAGER'] || ''
+
+        # Default to less, and make sure less is being passed the correct
+        # options
+        pager = "less -R -F -X" if pager.strip.empty? || pager =~ /^less\b/
+
+        pager
+      end
+
+      @system_pager = nil
+
+      def self.available?
+        if @system_pager.nil?
+          @system_pager =
+            begin
+              pager_executable = default_pager.split(' ').first
+              if Helpers::Platform.windows? || Helpers::Platform.windows_ansi?
+                `where /Q #{pager_executable}`
+              else
+                `which #{pager_executable}`
+              end
+              $CHILD_STATUS.success?
+            rescue StandardError
+              false
+            end
+        else
+          @system_pager
+        end
+      end
+
+      def initialize(*)
+        super
+        @tracker = PageTracker.new(height, width)
+        @buffer  = ""
+        @pager   = nil
+      end
+
+      def write(str)
+        if invoked_pager?
+          write_to_pager str
+        else
+          @tracker.record str
+          @buffer += str
+
+          write_to_pager @buffer if @tracker.page?
+        end
+      rescue Errno::EPIPE
+        raise StopPaging
+      end
+
+      def close
+        if invoked_pager?
+          pager.close
+        else
+          @out.puts @buffer
+        end
+      end
+
+      private
+
+      def write_to_pager(text)
+        pager.write @out.decolorize_maybe(text)
+      end
+
+      def invoked_pager?
+        @pager
+      end
+
+      def pager
+        @pager ||= IO.popen(self.class.default_pager, 'w')
+      end
+    end
+
+    # `PageTracker` tracks output to determine whether it's likely to take
+    # up a whole page. This doesn't need to be super precise, but we can
+    # use it for `SimplePager` and to avoid invoking the system pager
+    # unnecessarily.
+    #
+    # One simplifying assumption is that we don't need `#page?` to return
+    # `true` on the basis of an incomplete line. Long lines should be
+    # counted as multiple lines, but we don't have to transition from
+    # `false` to `true` until we see a newline.
+    class PageTracker
+      def initialize(rows, cols)
+        @rows = rows
+        @cols = cols
+        reset
+      end
+
+      def record(str)
+        str.lines.each do |line|
+          if line.end_with? "\n"
+            @row += ((@col + line_length(line) - 1) / @cols) + 1
+            @col  = 0
+          else
+            @col += line_length(line)
+          end
+        end
+      end
+
+      def page?
+        @row >= @rows
+      end
+
+      def reset
+        @row = 0
+        @col = 0
+      end
+
+      private
+
+      # Approximation of the printable length of a given line, without the
+      # newline and without ANSI color codes.
+      def line_length(line)
+        line.chomp.gsub(/\e\[[\d;]*m/, '').length
+      end
+    end
+  end
+end