match atx section title more efficiently

2 files changed, 15 insertions, 15 deletions

diff --git a/lib/asciidoctor.rb b/lib/asciidoctor.rb
index 7de5b39a..5d566f16 100644
--- a/lib/asciidoctor.rb
+++ b/lib/asciidoctor.rb
@@ -621,23 +621,23 @@ module Asciidoctor
 
     ## Section titles
 
-    # Matches a single-line (Atx-style) section title.
+    # Matches an Atx (single-line) section title.
     #
     # Examples
     #
     #   == Foo
-    #   # ^ a level 1 (h2) section title
+    #   // ^ a level 1 (h2) section title
     #
     #   == Foo ==
-    #   # ^ also a level 1 (h2) section title
+    #   // ^ also a level 1 (h2) section title
     #
-    # match[1] is the delimiter, whose length determines the level
-    # match[2] is the title itself
-    # match[3] is an inline anchor, which becomes the section id
-    AtxSectionTitleRx = /^(=={0,5}|#\#{0,5})[ \t]+(.+?)(?:[ \t]+\1)?$/
+    AtxSectionTitleRx = /^(=={0,5})[ \t]+(.+?)(?:[ \t]+\1)?$/
 
-    # Matches the restricted section name for a two-line (Setext-style) section title.
-    # The name cannot begin with a dot and has at least one alphanumeric character.
+    # Matches an extended Atx section title that includes support for the Markdown variant.
+    ExtAtxSectionTitleRx = /^(=={0,5}|#\#{0,5})[ \t]+(.+?)(?:[ \t]+\1)?$/
+
+    # Matches the title only (first line) of an Setext (two-line) section title.
+    # The title cannot begin with a dot and must have at least one alphanumeric character.
     SetextSectionTitleRx = /^((?=.*#{CG_WORD}+.*)[^.].*?)$/
 
     # Matches an anchor (i.e., id + optional reference text) inside a section title.
diff --git a/lib/asciidoctor/parser.rb b/lib/asciidoctor/parser.rb
index 8a0c87a4..775b0790 100644
--- a/lib/asciidoctor/parser.rb
+++ b/lib/asciidoctor/parser.rb
@@ -1651,10 +1651,10 @@ class Parser
     is_single_line_section_title?(line1) || (line2.nil_or_empty? ? nil : is_two_line_section_title?(line1, line2))
   end
 
-  def self.is_single_line_section_title?(line1)
-    if (line1.start_with?('=') || (Compliance.markdown_syntax && line1.start_with?('#'))) && AtxSectionTitleRx =~ line1
-    #if line1.start_with?('=', '#') && AtxSectionTitleRx =~ line1 && (line1.start_with?('=') || Compliance.markdown_syntax)
-      # NOTE level is 1 less than number of line markers
+  # NOTE level is 1 less than number of line markers
+  def self.is_single_line_section_title?(line)
+    if Compliance.markdown_syntax ? ((line.start_with? '=', '#') && ExtAtxSectionTitleRx =~ line) :
+        ((line.start_with? '=') && AtxSectionTitleRx =~ line)
       $1.length - 1
     end
   end
@@ -1714,8 +1714,8 @@ class Parser
     sect_id = sect_reftext = nil
     line1 = reader.read_line
 
-    #if line1.start_with?('=', '#') && AtxSectionTitleRx =~ line1 && (line1.start_with?('=') || Compliance.markdown_syntax)
-    if (line1.start_with?('=') || (Compliance.markdown_syntax && line1.start_with?('#'))) && AtxSectionTitleRx =~ line1
+    if Compliance.markdown_syntax ? ((line1.start_with? '=', '#') && ExtAtxSectionTitleRx =~ line1) :
+        ((line1.start_with? '=') && AtxSectionTitleRx =~ line1)
       # NOTE level is 1 less than number of line markers
       sect_level, sect_title, single_line = $1.length - 1, $2, true
       if sect_title.end_with?(']]') && InlineSectionAnchorRx =~ sect_title && !$1 # escaped