process pass inline macro with empty text; invert extract logic

3 files changed, 16 insertions, 9 deletions

diff --git a/lib/asciidoctor.rb b/lib/asciidoctor.rb
index b4e0f7db..e4c3cbe7 100644
--- a/lib/asciidoctor.rb
+++ b/lib/asciidoctor.rb
@@ -971,7 +971,7 @@ module Asciidoctor
     #   $$text$$
     #   pass:quotes[text]
     #
-    PassInlineMacroRx = /(?:(?:(\\?)\[([^\]]+?)\])?(\\{0,2})(\+{2,3}|\$\$)(#{CC_ALL}*?)\4|(\\?)pass:([a-z,]*)\[(#{CC_ALL}*?[^\\])\])/m
+    PassInlineMacroRx = /(?:(?:(\\?)\[([^\]]+?)\])?(\\{0,2})(\+{2,3}|\$\$)(#{CC_ALL}*?)\4|(\\?)pass:([a-z,]*)\[(|#{CC_ALL}*?[^\\])\])/m
 
     # Matches an xref (i.e., cross-reference) inline macro, which may span multiple lines.
     #
diff --git a/lib/asciidoctor/substitutors.rb b/lib/asciidoctor/substitutors.rb
index 831ba7bf..ca505d14 100644
--- a/lib/asciidoctor/substitutors.rb
+++ b/lib/asciidoctor/substitutors.rb
@@ -167,14 +167,7 @@ module Substitutors
       m = $~
       preceding = nil
 
-      if (boundary = m[4]).nil_or_empty? # pass:[]
-        if m[6] == '\\'
-          # NOTE we don't look for nested pass:[] macros
-          next m[0][1..-1]
-        end
-
-        @passthroughs[pass_key = @passthroughs.size] = {:text => (unescape_brackets m[8]), :subs => (m[7].nil_or_empty? ? [] : (resolve_pass_subs m[7]))}
-      else # $$, ++ or +++
+      if (boundary = m[4]) # $$, ++, or +++
         # skip ++ in compat mode, handled as normal quoted text
         if compat_mode && boundary == '++'
           next m[2].nil_or_empty? ?
@@ -217,6 +210,13 @@ module Substitutors
         else
           @passthroughs[pass_key] = {:text => content, :subs => subs}
         end
+      else # pass:[]
+        if m[6] == '\\'
+          # NOTE we don't look for nested pass:[] macros
+          next m[0][1..-1]
+        end
+
+        @passthroughs[pass_key = @passthroughs.size] = {:text => (unescape_brackets m[8]), :subs => (m[7].nil_or_empty? ? [] : (resolve_pass_subs m[7]))}
       end
 
       %(#{preceding}#{PASS_START}#{pass_key}#{PASS_END})
diff --git a/test/substitutions_test.rb b/test/substitutions_test.rb
index 1e98670d..34e6f076 100644
--- a/test/substitutions_test.rb
+++ b/test/substitutions_test.rb
@@ -1360,6 +1360,13 @@ EOS
       assert_equal '<strong><html5></strong>', result
     end
 
+    test 'should allow content of inline pass macro to be empty' do
+      para = block_from_string 'pass:[]'
+      result = para.extract_passthroughs para.source
+      assert_equal 1, para.passthroughs.size
+      assert_equal '', para.restore_passthroughs(result)
+    end
+
     # NOTE placeholder is surrounded by text to prevent reader from stripping trailing boundary char (unique to test scenario)
     test 'restore inline passthroughs without subs' do
       para = block_from_string("some #{Asciidoctor::Substitutors::PASS_START}" + '0' + "#{Asciidoctor::Substitutors::PASS_END} to study")