Support earlier than Ruby 2.4

Remove String#match? and heredoc with ">>~".

Author: aycabta

lib/rdoc/parser/ripper_state_lex.rb

@@ -479,7 +479,7 @@ def get_squashed_tk
 
   private def retrieve_heredoc_info(tk)
     name = tk[:text].gsub(/\A<<[-~]?(['"`]?)(.+)\1\z/, '\2')
-    indent = tk[:text].match?(/\A<<[-~]/)
+    indent = tk[:text] =~ /\A<<[-~]/
     [name, indent]
   end
 

lib/rdoc/parser/ruby.rb

@@ -1666,15 +1666,15 @@ def parse_statements(container, single = NORMAL, current_method = nil,
           past_tokens = @read.size > 1 ? @read[0..-2] : []
           nl_position = 0
           past_tokens.reverse.each_with_index do |read_tk, i|
-            if read_tk.match?(/^\n$/) then
+            if read_tk =~ /^\n$/ then
               nl_position = (past_tokens.size - 1) - i
               break
-            elsif read_tk.match?(/^#.*\n$/) then
+            elsif read_tk =~ /^#.*\n$/ then
               nl_position = ((past_tokens.size - 1) - i) + 1
               break
             end
           end
-          comment_only_line = past_tokens[nl_position..-1].all?{ |c| c.match?(/^\s+$/) }
+          comment_only_line = past_tokens[nl_position..-1].all?{ |c| c =~ /^\s+$/ }
           unless comment_only_line then
             tk = get_tk
           end

test/test_rdoc_parser_ruby.rb

@@ -2587,15 +2587,15 @@ def test_parse_statements_postfix_if_after_heredocbeg
     util_parser <<RUBY
 class Foo
   def blah()
-    <<~EOM if true
+    <<-EOM if true
     EOM
   end
 end
 RUBY
 
     expected = <<EXPTECTED
   <span class="ruby-keyword">def</span> <span class="ruby-identifier">blah</span>()
-    <span class="ruby-identifier">&lt;&lt;~EOM</span> <span class="ruby-keyword">if</span> <span class="ruby-keyword">true</span>
+    <span class="ruby-identifier">&lt;&lt;-EOM</span> <span class="ruby-keyword">if</span> <span class="ruby-keyword">true</span>
 <span class="ruby-value"></span><span class="ruby-identifier">    EOM</span>
   <span class="ruby-keyword">end</span>
 EXPTECTED
@@ -2608,7 +2608,7 @@ def blah()
 
     blah = foo.method_list.first
     markup_code = blah.markup_code.sub(/^.*\n/, '')
-    assert_equal markup_code, expected
+    assert_equal expected, markup_code
   end
 
   def test_parse_statements_method_oneliner_with_regexp