lexer.rb: no dedent strings in middle

* ext/ripper/lib/ripper/lexer.rb (on_heredoc_dedent): dedent only
  strings at the beginning, not strings in middle.
  [ruby-core:83343] [Bug #14027]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60212 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/ripper/lib/ripper/lexer.rb

@@ -98,7 +98,7 @@ class Ripper
       ignored_sp = []
       heredoc = @buf.last
       heredoc.each_with_index do |e, i|
-        if Elem === e and e.event == :on_tstring_content
+        if Elem === e and e.event == :on_tstring_content and e.pos[1].zero?
           tok = e.tok.dup if w > 0 and /\A\s/ =~ e.tok
           if (n = dedent_string(e.tok, w)) > 0
             if e.tok.empty?

test/ripper/test_lexer.rb

@@ -51,4 +51,23 @@ class TestRipper::Lexer < Test::Unit::TestCase
     ]
     assert_equal expect, Ripper.lex(src).map {|e| e[1]}
   end
+
+  def test_space_after_expr_in_heredoc
+    src = <<~'E'
+    <<~B
+     #{1} a
+    B
+    E
+    expect = %I[
+      on_heredoc_beg
+      on_nl
+      on_ignored_sp
+      on_embexpr_beg
+      on_int
+      on_embexpr_end
+      on_tstring_content
+      on_heredoc_end
+    ]
+    assert_equal expect, Ripper.lex(src).map {|e| e[1]}
+  end
 end