Parsing for character literals

Parse to single-character string.
Tests included

lib/parser.rb

@@ -88,6 +88,19 @@ def pop_token(input)
               # Official Scheme valid identifiers:
               # when /\A([A-Za-z!\$%&\*\.\/:<=>\?@\^_~][A-Za-z0-9!\$%&\*\+\-\.\/:<=>\?@\^_~]*)/ # symbol
               # when /\A([^-0-9\. \n\)][^ \n\)]*)/
+            when /\A#\\(.)/ # Character literal
+              char = Regexp.last_match[1]
+              input[0 ... 2] = ''
+              if input[0 ... 5] == 'space'
+                input[0 ... 5] = ''
+                char = ' '
+              elsif input[0 ... 7] == 'newline'
+                input[0 ... 7] = ''
+                char = "\n"
+              else
+                input[0 ... 1] = ''
+              end
+              return char
             when /\A([^ \n\)]+)/ # symbols
               # puts "#{Regexp.last_match[1]} - #{@@lines}"
               # cannot begin with a character that may begin a number

test/test_parser.rb

@@ -106,13 +106,14 @@ def test_explicitly_positive_floats
     assert_parses_to "+0.10", 0.1
   end
 
-#   def test_character_literals
-#     assert_parses_to "#\e", "e"
-#     assert_parses_to "#\A", "A"
-#     assert_parses_to "#\(", "("
-#     assert_parses_to "#\space", ' '
-#     assert_parses_to "#\newline", "\n"
-#   end
+   def test_character_literals
+     # must escape ruby string with backslask
+     assert_parses_to "#\\e", "e"
+     assert_parses_to "#\\A", "A"
+     assert_parses_to "#\\(", "("
+     assert_parses_to "#\\space", ' '
+     assert_parses_to "#\\newline", "\n"
+   end
 
   def test_quote
     assert_parses_to "'foo", [:quote.sym, :foo.sym]