Replaced SingleCharGroup.new('') with PlaceHolderGroup.new

This makes the intention of these slightly-hacky "placeholders" more obvious. For example, /\K/, /\A/, /(?i)/, /a b/x all require a "placeholder" for these groups, due to how the regexp parser works.

Author: Tom Lord

coverage/coverage-badge.png

@@ -48,6 +48,16 @@ def result
  end
  end
 
+ # Used as a workaround for when a grep is expected to be returned,
+ # but there are no results for the group.
+ # i.e. PlaceHolderGroup.new.result == '' == SingleCharGroup.new('').result
+ # (But using PlaceHolderGroup makes it clearer what the intention is!)
+ class PlaceHolderGroup
+ def result
+ [GroupResult.new('')]
+ end
+ end
+
  class CharGroup
  prepend GroupWithIgnoreCase
  def initialize(chars, ignorecase)

lib/regexp-examples/groups.rb

@@ -46,20 +46,20 @@ def parse_group(repeaters)
  group = parse_after_backslash_group
  when '^'
  if @current_position == 0
- group = parse_single_char_group('') # Ignore the "illegal" character
+ group = PlaceHolderGroup.new # Ignore the "illegal" character
  else
  raise IllegalSyntaxError, "Anchors ('#{next_char}') cannot be supported, as they are not regular"
  end
  when '$'
  if @current_position == (regexp_string.length - 1)
- group = parse_single_char_group('') # Ignore the "illegal" character
+ group = PlaceHolderGroup.new # Ignore the "illegal" character
  else
  raise IllegalSyntaxError, "Anchors ('#{next_char}') cannot be supported, as they are not regular"
  end
  when /[#\s]/
  if @extended
  parse_extended_whitespace
- group = parse_single_char_group('') # Ignore the whitespace/comment
+ group = PlaceHolderGroup.new # Ignore the whitespace/comment
  else
  group = parse_single_char_group(next_char)
  end
@@ -104,7 +104,7 @@ def parse_after_backslash_group
  @current_position += ($1.length + 2)
  raise UnsupportedSyntaxError, "Named properties ({\\p#{$1}}) are not yet supported"
  when next_char == 'K' # Keep (special lookbehind that CAN be supported safely!)
- group = parse_single_char_group('') # Ignore it
+ group = PlaceHolderGroup.new
  when next_char == 'R' # Linebreak
  group = CharGroup.new(["\r\n", "\n", "\v", "\f", "\r"], @ignorecase) # A bit hacky...
  when next_char == 'g' # Subexpression call
@@ -114,13 +114,13 @@ def parse_after_backslash_group
  raise IllegalSyntaxError, "Anchors ('\\#{next_char}') cannot be supported, as they are not regular"
  when next_char =~ /[AG]/ # Start of string
  if @current_position == 1
- group = parse_single_char_group('') # Ignore the "illegal" character
+ group = PlaceHolderGroup.new
  else
  raise IllegalSyntaxError, "Anchors ('\\#{next_char}') cannot be supported, as they are not regular"
  end
  when next_char =~ /[zZ]/ # End of string
  if @current_position == (regexp_string.length - 1)
- group = parse_single_char_group('') # Ignore the "illegal" character
+ group = PlaceHolderGroup.new
  else
  raise IllegalSyntaxError, "Anchors ('\\#{next_char}') cannot be supported, as they are not regular"
  end
@@ -186,7 +186,7 @@ def parse_multi_group
  if next_char == ':' # e.g. /(?i:subexpr)/
  @current_position += 1
  else
- return parse_single_char_group('')
+ return PlaceHolderGroup.new
  end
  when %w(! =).include?(match[2]) # e.g. /(?=lookahead)/, /(?!neglookahead)/
  raise IllegalSyntaxError, "Lookaheads are not regular; cannot generate examples"