Add Reline as a fallback library for Readline

* lib/reine.rb, lib/reline/*: Reline is a readline stdlib compatible
  library.
* lib/readline.rb: Readline uses a fallback to Reline when ext/readline
  doesn't exist.
* tool/sync_default_gems.rb: add ruby/reline as a default gem.
* appveyor.yml: add "set RELINE_TEST_ENCODING=Windows-31J" for test suit
  of Reline, and add "--exclude readline" to "nmake test-all" on Visual
  Studio builds because of strange behavior.
* spec/ruby/library/readline/spec_helper.rb: skip Reline as with
  RbReadline.

appveyor.yml

@@ -63,9 +63,10 @@ for:
     - if not "%GEMS_FOR_TEST%" == "" \usr\bin\gem install --no-document %GEMS_FOR_TEST%
   test_script:
     - set /a JOBS=%NUMBER_OF_PROCESSORS%
+    - set RELINE_TEST_ENCODING=Windows-31J
     - nmake -l "TESTOPTS=-v -q" btest
     - nmake -l "TESTOPTS=-v -q" test-basic
-    - nmake -l "TESTOPTS=-q --subprocess-timeout-scale=3.0 --excludes=../test/excludes/_appveyor -j%JOBS% --exclude win32ole --exclude test_bignum --exclude test_syntax --exclude test_open-uri --exclude test_bundled_ca --exclude test_gc_compact" test-all
+    - nmake -l "TESTOPTS=-q --subprocess-timeout-scale=3.0 --excludes=../test/excludes/_appveyor -j%JOBS% --exclude readline --exclude win32ole --exclude test_bignum --exclude test_syntax --exclude test_open-uri --exclude test_bundled_ca --exclude test_gc_compact" test-all
     # separately execute tests without -j which may crash worker with -j.
     - nmake -l "TESTOPTS=-v --subprocess-timeout-scale=3.0 --excludes=../test/excludes/_appveyor" test-all TESTS="../test/win32ole ../test/ruby/test_bignum.rb ../test/ruby/test_syntax.rb ../test/open-uri/test_open-uri.rb ../test/rubygems/test_bundled_ca.rb ../test/ruby/test_gc_compact.rb"
     - nmake -l test-spec MSPECOPT=-fs # not using `-j` because sometimes `mspec -j` silently dies on Windows
@@ -108,6 +109,7 @@ for:
     - mingw32-make DESTDIR=../install install-nodoc
     - if not "%GEMS_FOR_TEST%" == "" ..\install\bin\gem install --no-document %GEMS_FOR_TEST%
   test_script:
+    - set RELINE_TEST_ENCODING=Windows-31J
     - mingw32-make test
     - mingw32-make test-all TESTOPTS="--retry --job-status=normal --show-skip --subprocess-timeout-scale=1.5 --excludes=../ruby/test/excludes/_appveyor -j %JOBS% --exclude win32ole --exclude test_open-uri --exclude test_gc_compact"
     # separately execute tests without -j which may crash worker with -j.

lib/readline.rb

@@ -0,0 +1,6 @@
+begin
+  require 'readline.so'
+rescue LoadError
+  require 'reline'
+  Readline = Reline
+end

lib/reline.rb

@@ -0,0 +1,197 @@
+require 'io/console'
+require 'reline/version'
+require 'reline/config'
+require 'reline/key_actor'
+require 'reline/key_stroke'
+require 'reline/line_editor'
+
+module Reline
+  extend self
+  FILENAME_COMPLETION_PROC = nil
+  USERNAME_COMPLETION_PROC = nil
+  HISTORY = Array.new
+
+  if RUBY_PLATFORM =~ /mswin|mingw/
+    IS_WINDOWS = true
+  else
+    IS_WINDOWS = false
+  end
+
+  CursorPos = Struct.new(:x, :y)
+
+  class << self
+    attr_accessor :basic_quote_characters
+    attr_accessor :completer_quote_characters
+    attr_accessor :completer_word_break_characters
+    attr_reader :completion_append_character
+    attr_accessor :completion_case_fold
+    attr_accessor :filename_quote_characters
+    attr_writer :input
+    attr_writer :output
+  end
+
+  @@ambiguous_width = nil
+  @@config = nil
+
+  @basic_quote_characters = '"\''
+  # TODO implement below
+  #@completer_quote_characters
+  #@completion_append_character
+  #@completion_case_fold
+  #@filename_quote_characters
+  def self.completion_append_character=(val)
+    if val.nil?
+      @completion_append_character = nil
+    elsif val.size == 1
+      @completion_append_character = val
+    elsif val.size > 1
+      @completion_append_character = val[0]
+    else
+      @completion_append_character = val
+    end
+  end
+
+  @@basic_word_break_characters = " \t\n`><=;|&{("
+  def self.basic_word_break_characters
+    @@basic_word_break_characters
+  end
+  def self.basic_word_break_characters=(v)
+    @@basic_word_break_characters = v
+  end
+
+  @@completer_word_break_characters = @@basic_word_break_characters.dup
+
+  @@completion_proc = nil
+  def self.completion_proc
+    @@completion_proc
+  end
+  def self.completion_proc=(p)
+    @@completion_proc = p
+  end
+
+  @@dig_perfect_match_proc = nil
+  def self.dig_perfect_match_proc
+    @@dig_perfect_match_proc
+  end
+  def self.dig_perfect_match_proc=(p)
+    @@dig_perfect_match_proc = p
+  end
+
+  if IS_WINDOWS
+    require 'reline/windows'
+  else
+    require 'reline/ansi'
+  end
+
+  def retrieve_completion_block(line, byte_pointer)
+    break_regexp = /[#{Regexp.escape(@@basic_word_break_characters)}]/
+    before_pointer = line.byteslice(0, byte_pointer)
+    break_point = before_pointer.rindex(break_regexp)
+    if break_point
+      preposing = before_pointer[0..(break_point)]
+      block = before_pointer[(break_point + 1)..-1]
+    else
+      preposing = ''
+      block = before_pointer
+    end
+    postposing = line.byteslice(byte_pointer, line.bytesize)
+    [preposing, block, postposing]
+  end
+
+  def readmultiline(prompt = '', add_hist = false, &confirm_multiline_termination)
+    if block_given?
+      inner_readline(prompt, add_hist, true, &confirm_multiline_termination)
+    else
+      inner_readline(prompt, add_hist, true)
+    end
+
+    if add_hist and @line_editor.whole_buffer and @line_editor.whole_buffer.chomp.size > 0
+      Reline::HISTORY << @line_editor.whole_buffer
+    end
+
+    @line_editor.whole_buffer
+  end
+
+  def readline(prompt = '', add_hist = false)
+    inner_readline(prompt, add_hist, false)
+
+    if add_hist and @line_editor.line and @line_editor.line.chomp.size > 0
+      Reline::HISTORY << @line_editor.line.chomp
+    end
+
+    @line_editor.line
+  end
+
+  def inner_readline(prompt, add_hist, multiline, &confirm_multiline_termination)
+    if @@config.nil?
+      @@config = Reline::Config.new
+      @@config.read
+    end
+    otio = prep
+
+    may_req_ambiguous_char_width
+    @line_editor = Reline::LineEditor.new(@@config, prompt)
+    if multiline
+      @line_editor.multiline_on
+      if block_given?
+        @line_editor.confirm_multiline_termination_proc = confirm_multiline_termination
+      end
+    end
+    @line_editor.completion_proc = @@completion_proc
+    @line_editor.dig_perfect_match_proc = @@dig_perfect_match_proc
+    @line_editor.retrieve_completion_block = method(:retrieve_completion_block)
+    @line_editor.rerender
+
+    if IS_WINDOWS
+      config = {
+        key_mapping: {
+          [224, 72] => :ed_prev_history,    # ↑
+          [224, 80] => :ed_next_history,    # ↓
+          [224, 77] => :ed_next_char,       # →
+          [224, 75] => :ed_prev_char        # ←
+        }
+      }
+    else
+      config = {
+        key_mapping: {
+          [27, 91, 65] => :ed_prev_history,    # ↑
+          [27, 91, 66] => :ed_next_history,    # ↓
+          [27, 91, 67] => :ed_next_char,       # →
+          [27, 91, 68] => :ed_prev_char        # ←
+        }
+      }
+    end
+
+    key_stroke = Reline::KeyStroke.new(config)
+    begin
+      while c = getc
+        key_stroke.input_to!(c)&.then { |inputs|
+          inputs.each { |c|
+            @line_editor.input_key(c)
+            @line_editor.rerender
+          }
+        }
+        break if @line_editor.finished?
+      end
+      Reline.move_cursor_column(0)
+    rescue StandardError => e
+      deprep(otio)
+      raise e
+    end
+
+    deprep(otio)
+  end
+
+  def may_req_ambiguous_char_width
+    return if @@ambiguous_width
+    Reline.move_cursor_column(0)
+    print "\u{25bd}"
+    @@ambiguous_width = Reline.cursor_pos.x
+    Reline.move_cursor_column(0)
+    Reline.erase_after_cursor
+  end
+
+  def self.ambiguous_width
+    @@ambiguous_width
+  end
+end

lib/reline/ansi.rb

@@ -0,0 +1,87 @@
+module Reline
+  def getc
+    c = nil
+    until c
+      return nil if @line_editor.finished?
+      result = select([$stdin], [], [], 0.1)
+      next if result.nil?
+      c = $stdin.read(1)
+    end
+    c.ord
+  end
+
+  def self.get_screen_size
+    $stdin.winsize
+  end
+
+  def self.set_screen_size(rows, columns)
+    $stdin.winsize = [rows, columns]
+    self
+  end
+
+  def self.cursor_pos
+    res = ''
+    $stdin.raw do |stdin|
+      $stdout << "\e[6n"
+      $stdout.flush
+      while (c = stdin.getc) != 'R'
+        res << c if c
+      end
+    end
+    m = res.match(/(?<row>\d+);(?<column>\d+)/)
+    CursorPos.new(m[:column].to_i - 1, m[:row].to_i - 1)
+  end
+
+  def self.move_cursor_column(x)
+    print "\e[#{x + 1}G"
+  end
+
+  def self.move_cursor_up(x)
+    if x > 0
+      print "\e[#{x}A" if x > 0
+    elsif x < 0
+      move_cursor_down(-x)
+    end
+  end
+
+  def self.move_cursor_down(x)
+    if x > 0
+      print "\e[#{x}B" if x > 0
+    elsif x < 0
+      move_cursor_up(-x)
+    end
+  end
+
+  def self.erase_after_cursor
+    print "\e[K"
+  end
+
+  def self.scroll_down(x)
+    return if x.zero?
+    print "\e[#{x}S"
+  end
+
+  def self.clear_screen
+    print "\e[2J"
+    print "\e[1;1H"
+  end
+
+  def prep
+    int_handle = Signal.trap('INT', 'IGNORE')
+    otio = `stty -g`.chomp
+    setting = ' -echo -icrnl cbreak'
+    if (`stty -a`.scan(/-parenb\b/).first == '-parenb')
+      setting << ' pass8'
+    end
+    setting << ' -ixoff'
+    `stty #{setting}`
+    Signal.trap('INT', int_handle)
+    otio
+  end
+
+  def deprep(otio)
+    int_handle = Signal.trap('INT', 'IGNORE')
+    `stty #{otio}`
+    Signal.trap('INT', int_handle)
+  end
+end