X-Git-Url: https://git.plutz.net/?p=cgilite;a=blobdiff_plain;f=markdown.awk;h=e63541bebfa78ffc70053ca23a1d94ff6b586c66;hp=134002db06d363a977d8318c38b02ca7cf6ccd9a;hb=76805496f22af93204e2c6225f2e4f32902bcf2b;hpb=3d2264ce0ed3d74b084531e364e27e5427ac1cf4

diff --git a/markdown.awk b/markdown.awk
index 134002d..e63541b 100755
--- a/markdown.awk
+++ b/markdown.awk
@@ -4,26 +4,23 @@
 # EXPERIMENTAL Markdown processor with minimal dependencies.
 # Meant to support all features of John Grubers basic Markdown
 # + a number of common extensions, mostly inspired by Pandoc Markdown
-#
-# ToDo:
-# - HTML processing / escaping (according to environment flag)
-# - em-dashes and arrows
 
 # Supported Features / TODO:
 # ==========================
-# [x] done    [ ] todo    [-] not planned    [?] unsure
+# [x] done    [ ] todo    [-] not planned    ? unsure
 #
 # Basic Markdown - Block elements:
 # -------------------------------
 # - [x] Paragraphs
-#   - [ ] Double space line breaks
+#   - [x] Double space line breaks
 # - [x] Proper block element nesting
 # - [x] Headings
 # - [x] ATX-Style Headings
 # - [x] Blockquotes
 # - [x] Lists (ordered, unordered)
 # - [x] Code blocks (using indention)
-# - [ ] Horizontal rules
+# - [x] Horizontal rules
+# - [x] Verbatim HTML block (disabled by default)
 #
 # Basic Markdown - Inline elements:
 # ---------------------------------
@@ -31,42 +28,49 @@
 # - [x] Reference style links
 # - [x] Emphasis *em*/**strong** (*Asterisk*, _Underscore_)
 # - [x] `code`, also ``code containing `backticks` ``
-# - [ ] Images / reference style images
+# - [x] Images / reference style images
 # - [x] <automatic links>
 # - [x] backslash escapes
+# - [x] Verbatim HTML inline (disabled by default)
+# - [x] HTML escaping
+#
+# NOTE: Set the environment variable MD_HTML=true to enable verbatim HTML
 #
 # Extensions - Block elements:
 # ----------------------------
-# - [?] Heading identifiers (phpmarkdown, pandoc)
-# - [x] Fenced code blocks (phpmarkdown, pandoc)
-#   - [-] Fenced code attributes
+# -  ?  Heading identifiers (php md, pandoc)
+# - [x] Automatic heading identifiers (custom)
+# - [x] Fenced code blocks (php md, pandoc)
+#   - [x] Fenced code attributes
 # - [ ] Tables
-#   - [?] Simple table (pandoc)
-#   - [?] Multiline table (pandoc)
-#   - [?] Grid table (pandoc)
-#   - [?] Pipe table (phpmarkdown, pandoc)
+#   -  ?  Simple table (pandoc)
+#   -  ?  Multiline table (pandoc)
+#   -  ?  Grid table (pandoc)
+#   -  ?  Pipe table (php md pandoc)
 # - [x] Line blocks (pandoc)
-# - [ ] Task lists (pandoc)
-# - [ ] Definition lists (phpmarkdown, pandoc)
+# - [x] Task lists (pandoc)
+# - [ ] Definition lists (php md, pandoc)
 # - [-] Numbered example lists (pandoc)
 # - [-] Metadata blocks (pandoc)
-# - [-] Fenced Divs (pandoc)
+# - [x] Metadata blocks (custom)
+# - [x] Fenced Divs (pandoc)
 #
 # Extensions - Inline elements:
 # ----------------------------
-# - [ ] Ignore embedded_underscores (phpmarkdown, pandoc)
+# - [x] Ignore embedded_underscores (php md, pandoc)
 # - [x] ~~strikeout~~ (pandoc)
 # - [x] ^Superscript^ ~Subscript~ (pandoc)
 # - [-] Bracketed spans (pandoc)
 #   - [-] Inline attributes (pandoc)
 # - [-] TEX-Math (pandoc)
-# - [?] Footnotes (phpmarkdown)
-# - [?] Abbreviations (phpmarkdown)
-# - [?] "Curly quotes" (smartypants)
+# -  ?  Footnotes (php md)
+# -  ?  Abbreviations (php md)
+# -  ?  "Curly quotes" (smartypants)
 # - [ ] em-dashes (--) (smartypants old)
-# - [?] ... three-dot ellipsis (smartypants)
+# -  ?  ... three-dot ellipsis (smartypants)
 # - [-] en-dash (smartypants)
 # - [ ] Automatic em-dash / en-dash
+# - [ ] Automatic -> Arrows <-
 
 function debug(text) { printf "\n---\n%s\n---\n", text > "/dev/stderr"; }
 
@@ -81,7 +85,7 @@ function HTML ( text ) {
 }
 
 function inline( line, LOCAL, len, code, href, guard ) {
-  nu = "(\\\\\\\\|\\\\[^\\\\]|[^\\\\_])*"    # not underline (except when escaped)
+  nu = "(\\\\\\\\|\\\\[^\\\\]|[^\\\\_]|_[[:alnum:]])*"    # not underline (except when escaped)
   na = "(\\\\\\\\|\\\\[^\\\\]|[^\\\\\\*])*"  # not asterisk (except when escaped)
   ieu =  "_([^_[:space:]]|[^_[:space:]]" nu "[^_[:space:]])_"                 # inner <em> (underline)
   isu = "__([^_[:space:]]|[^_[:space:]]" nu "[^_[:space:]])__"                # inner <strong> (underline)
@@ -95,6 +99,10 @@ function inline( line, LOCAL, len, code, href, guard ) {
   } else if ( line ~ /^\\[]\\`\*_\{\}\(\)#\+-\.![]/) {
     return substr(line, 2, 1) inline( substr(line, 3) );
 
+  # hard brakes
+  } else if ( match(line, /^  \n/) ) {
+    return "<br />\n" inline( substr(line, RLENGTH + 1) );
+
   #  ``code spans``
   } else if ( match( line, /^`+/) ) {
     len = RLENGTH
@@ -115,12 +123,18 @@ function inline( line, LOCAL, len, code, href, guard ) {
     href = HTML( substr( line, 2, len - 2) );
     return "<a href=\"" href "\">" href "</a>" inline( substr( line, len + 1) );
 
+  # quick link email
+  } else if ( match( line, /^<[a-zA-Z0-9.!#$%&'\''*+\/=?^_`{|}~-]+@[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*>/ ) ) {
+    len = RLENGTH;
+    href = HTML( substr( line, 2, len - 2) );
+    return "<a href=\"mailto:" href "\">" href "</a>" inline( substr( line, len + 1) );
+
   # inline links
-  } else if ( match(line, /^\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/) ) {
+  } else if ( match(line, /^\[([^]]+)\]\(([^"\)]+)([[:space:]]+"([^"]+)")?\)/) ) {
     len = RLENGTH;
-    text  = gensub(/^\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/, "\\1", "g", line);
-    href  = gensub(/^\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/, "\\2", "g", line);
-    title = gensub(/^\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/, "\\4", "g", line);
+    text  = gensub(/^\[([^]]+)\]\(([^"\)]+)([[:space:]]+"([^"]+)")?\)/, "\\1", 1, substr(line, 1, len) );
+    href  = gensub(/^\[([^]]+)\]\(([^"\)]+)([[:space:]]+"([^"]+)")?\)/, "\\2", 1, substr(line, 1, len) );
+    title = gensub(/^\[([^]]+)\]\(([^"\)]+)([[:space:]]+"([^"]+)")?\)/, "\\4", 1, substr(line, 1, len) );
     if ( title ) {
       return "<a href=\"" HTML(href) "\" title=\"" HTML(title) "\">" inline( text ) "</a>" inline( substr( line, len + 1) );
     } else {
@@ -130,15 +144,41 @@ function inline( line, LOCAL, len, code, href, guard ) {
   # reference style links
   } else if ( match(line, /^\[([^]]+)\] ?\[([^]]*)\]/ ) ) {
     len = RLENGTH;
-    text = gensub(/^\[([^\n]+)\] ?\[([^\n]*)\].*/, "\\1", 1, line);
-      id = gensub(/^\[([^\n]+)\] ?\[([^\n]*)\].*/, "\\2", 1, line);
+    text = gensub(/^\[([^\n]+)\] ?\[([^\n]*)\].*/, "\\1", 1, substr(line, 1, len) );
+      id = gensub(/^\[([^\n]+)\] ?\[([^\n]*)\].*/, "\\2", 1, substr(line, 1, len) );
+    if ( ! id ) id = text;
+    if ( rl_href[id] && rl_title[id] ) {
+      return "<a href=\"" HTML(rl_href[id]) "\" title=\"" HTML(rl_title[id]) "\">" inline(text) "</a>" inline( substr( line, len + 1) );
+    } else if ( rl_href[id] ) {
+      return "<a href=\"" HTML(rl_href[id]) "\">" inline(text) "</a>" inline( substr( line, len + 1) );
+    } else {
+      return "" HTML(substr(line, 1, len)) inline( substr(line, len + 1) );
+    }
+
+  # inline images
+  } else if ( match(line, /^!\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/) ) {
+    len = RLENGTH;
+    text  = gensub(/^!\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/, "\\1", "g", substr(line, 1, len) );
+    href  = gensub(/^!\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/, "\\2", "g", substr(line, 1, len) );
+    title = gensub(/^!\[([^]]+)\]\(([^"\)]+)([ \t]+"([^"]+)")?\)/, "\\4", "g", substr(line, 1, len) );
+    if ( title ) {
+      return "<img src=\"" HTML(href) "\" alt=\"" HTML(text) "\" title=\"" HTML(title) "\" />" inline( substr( line, len + 1) );
+    } else {
+      return "<img src=\"" HTML(href) "\" alt=\"" HTML(text) "\" />" inline( substr( line, len + 1) );
+    }
+
+  # reference style images
+  } else if ( match(line, /^!\[([^]]+)\] ?\[([^]]*)\]/ ) ) {
+    len = RLENGTH;
+    text = gensub(/^!\[([^\n]+)\] ?\[([^\n]*)\].*/, "\\1", 1, substr(line, 1, len) );
+      id = gensub(/^!\[([^\n]+)\] ?\[([^\n]*)\].*/, "\\2", 1, substr(line, 1, len) );
     if ( ! id ) id = text;
     if ( rl_href[id] && rl_title[id] ) {
-      return "<a href=\"" rl_href[id] "\" title=\"" rl_title[id] "\">" inline(text) "</a>" inline( substr( line, len + 1) );
+      return "<img src=\"" HTML(rl_href[id]) "\" alt=\"" HTML(text) "\" title=\"" HTML(rl_title[id]) "\" />" inline( substr( line, len + 1) );
     } else if ( rl_href[id] ) {
-      return "<a href=\"" rl_href[id] "\">" inline(text) "</a>" inline( substr( line, len + 1) );
+      return "<img src=\"" HTML(rl_href[id]) "\" alt=\"" HTML(text) "\" />" inline( substr( line, len + 1) );
     } else {
-      return "" substr(line, 1, len) inline( substr(line, len + 1) );
+      return "" HTML(substr(line, 1, len)) inline( substr(line, len + 1) );
     }
 
   #  ~~strikeout~~ (pandoc)
@@ -156,37 +196,98 @@ function inline( line, LOCAL, len, code, href, guard ) {
     len = RLENGTH;
     return "<sub>" inline( substr( line, 2, len - 2 ) ) "</sub>" inline( substr( line, len + 1 ) );
 
-  #  __strong__
-  } else if ( match(line, "^__(([^_[:space:]]|" ieu ")|([^_[:space:]]|" ieu ")(" nu "|" ieu ")*([^_[:space:]]|" ieu "))__") ) {
+  # ignore embedded underscores (pandoc, php md)
+  } else if ( match(line, "^[[:alnum:]](__|_)") ) {
+    return HTML(substr( line, 1, RLENGTH)) inline( substr(line, RLENGTH + 1) );
+
+  #  __strong__$
+  } else if ( match(line, "^__(([^_[:space:]]|" ieu ")|([^_[:space:]]|" ieu ")(" nu "|" ieu ")*([^_[:space:]]|" ieu "))__$") ) {
     len = RLENGTH;
     return "<strong>" inline( substr( line, 3, len - 4 ) ) "</strong>" inline( substr( line, len + 1 ) );
 
+  #  __strong__
+  } else if ( match(line, "^__(([^_[:space:]]|" ieu ")|([^_[:space:]]|" ieu ")(" nu "|" ieu ")*([^_[:space:]]|" ieu "))__[[:space:][:punct:]]") ) {
+    len = RLENGTH;
+    return "<strong>" inline( substr( line, 3, len - 5 ) ) "</strong>" inline( substr( line, len) );
+
   #  **strong**
   } else if ( match(line, "^\\*\\*(([^\\*[:space:]]|" iea ")|([^\\*[:space:]]|" iea ")(" na "|" iea ")*([^\\*[:space:]]|" iea "))\\*\\*") ) {
     len = RLENGTH;
     return "<strong>" inline( substr( line, 3, len - 4 ) ) "</strong>" inline( substr( line, len + 1 ) );
 
-  #  _em_
-  } else if ( match(line, "^_(([^_[:space:]]|" isu ")|([^_[:space:]]|" isu ")(" nu "|" isu ")*([^_[:space:]]|" isu "))_") ) {
+  #  _em_$
+  } else if ( match(line, "^_(([^_[:space:]]|" isu ")|([^_[:space:]]|" isu ")(" nu "|" isu ")*([^_[:space:]]|" isu "))_$") ) {
     len = RLENGTH;
     return "<em>" inline( substr( line, 2, len - 2 ) ) "</em>" inline( substr( line, len + 1 ) );
 
+  #  _em_
+  } else if ( match(line, "^_(([^_[:space:]]|" isu ")|([^_[:space:]]|" isu ")(" nu "|" isu ")*([^_[:space:]]|" isu "))_[[:space:][:punct:]]") ) {
+    len = RLENGTH;
+    return "<em>" inline( substr( line, 2, len - 3 ) ) "</em>" inline( substr( line, len ) );
+
   #  *em*
   } else if ( match(line, "^\\*(([^\\*[:space:]]|" isa ")|([^\\*[:space:]]|" isa ")(" na "|" isa ")*([^\\*[:space:]]|" isa "))\\*") ) {
     len = RLENGTH;
     return "<em>" inline( substr( line, 2, len - 2 ) ) "</em>" inline( substr( line, len + 1 ) );
 
+  # Macros
+  } else if ( AllowMacros && match( line, /^<<([^>]|>[^>])+>>/) ) {
+    len = RLENGTH;
+    return macro( substr( line, 3, len - 4 ) ) inline(substr(line, len + 1));
+
+  # Verbatim inline HTML
+  } else if ( AllowHTML && match( line, /^(<!--([^-]|-[^-]|--[^>])*-->|<\?([^\?]|\?[^>])*\?>|<![A-Z][^>]*>|<!\[CDATA\[([^\]]|\][^\]]|\]\][^>])*\]\]>|<\/[A-Za-z][A-Za-z0-9-]*[[:space:]]*>|<[A-Za-z][A-Za-z0-9-]*([[:space:]]+[A-Za-z_:][A-Za-z0-9_\.:-]*([[:space:]]*=[[:space:]]*([[:space:]"'=<>`]+|"[^"]*"|'[^']*'))?)*[[:space:]]*\/?>)/) ) {
+    len = RLENGTH;
+    return substr( line, 1, len) inline(substr(line, len + 1));
+
+  # Literal HTML entities
+  } else if ( match( line, /^&([a-zA-Z]{2,32}|#[0-9]{1,7}|#[xX][0-9a-fA-F]{1,6});/) ) {
+    len = RLENGTH;
+    return substr( line, 1, len ) inline(substr(line, len + 1));
+
+  # Escape lone HTML character
+  } else if ( match( line, /^[&<>"']/) ) {
+    return HTML(substr(line, 1, 1)) inline(substr(line, 2));
+
   #  continue walk over string
   } else {
     return substr(line, 1, 1) inline( substr(line, 2) );
   }
 }
 
-function _block( block, LOCAL, st, len, hlvl, htxt, guard, code, indent ) {
+function _block( block, LOCAL, st, len, hlvl, htxt, guard, code, indent, attrib ) {
   gsub( /^\n+|\n+$/, "", block );
 
   if ( block == "" ) {
     return "";
+
+  # HTML #2 #3 #4 $5
+  } else if ( AllowHTML && match( block, /(^|\n) ? ? ?(<!--([^-]|-[^-]|--[^>])*(-->|$)|<\?([^\?]|\?[^>])*(\?>|$)|<![A-Z][^>]*(>|$)|<!\[CDATA\[([^\]]|\][^\]]|\]\][^>])*(\]\]>|$))/) ) {
+    len = RLENGTH; st = RSTART;
+    return _block(substr(block, 1, st - 1)) substr(block, st, len) _block(substr(block, st + len));
+
+  # HTML #6
+  } else if ( AllowHTML && match( tolower(block), /(^|\n) ? ? ?<\/?(address|article|aside|base|basefont|blockquote|body|caption|center|col|colgroup|dd|details|dialog|dir|div|dl|dt|fieldset|figcaption|figure|footer|form|frame|frameset|h[123456]|head|header|hr|html|iframe|legend|li|link|main|menu|menuitem|nav|noframes|ol|optgroup|option|p|param|section|source|summary|table|tbody|td|tfoot|th|thead|title|tr|track|ul)([[:space:]\n>]|\/>)([^\n]|\n[ \t]*[^\n])*(\n[[:space:]]*\n|$)/) ) {
+    len = RLENGTH; st = RSTART;
+    return _block(substr(block, 1, st - 1)) substr(block, st, len) _block(substr(block, st + len));
+
+  # HTML #1
+  } else if ( AllowHTML && match( tolower(block), /(^|\n) ? ? ?<(script|pre|style)([[:space:]\n>]).*(<\/script>|<\/pre>|<\/style>|$)/) ) {
+    len = RLENGTH; st = RSTART;
+    match( tolower(substr(block, st, len)), /(<\/script>|<\/pre>|<\/style>)/);
+    len = RSTART + RLENGTH;
+    return _block(substr(block, 1, st - 1)) substr(block, st, len) _block(substr(block, st + len));
+
+  # HTML #7
+  } else if ( AllowHTML && match( block, /^ ? ? ?(<\/[A-Za-z][A-Za-z0-9-]*[[:space:]]*>|<[A-Za-z][A-Za-z0-9-]*([[:space:]]+[A-Za-z_:][A-Za-z0-9_\.:-]*([[:space:]]*=[[:space:]]*([[:space:]"'=<>`]+|"[^"]*"|'[^']*'))?)*[[:space:]]*\/?>)([[:space:]]*\n)([^\n]|\n[ \t]*[^\n])*(\n[[:space:]]*\n|$)/) ) {
+    len = RLENGTH; st = RSTART;
+    return substr(block, st, len) _block(substr(block, st + len));
+
+  # Metadata (custom, block starting with %something)
+  # Metadata is ignored but can be interpreted externally
+  } else if ( match(block, /^%[a-zA-Z]+([[:space:]][^\n]*)?(\n|$)(%[a-zA-Z]+([[:space:]][^\n]*)?(\n|$)|%([[:space:]][^\n]*)?(\n|$)|[ \t]+[^\n[:space:]][^\n]*(\n|$))*/) ) {
+    len = RLENGTH; st = RSTART;
+    return  _block( substr( block, len + 1) );
  
   # Blockquote (leading >)
   } else if ( match( block, /^> /) ) {
@@ -214,13 +315,34 @@ function _block( block, LOCAL, st, len, hlvl, htxt, guard, code, indent ) {
     return "<pre><code>" HTML( code ) "</code></pre>\n" \
            _block( substr( block, len + 1 ) );
 
+  # Fenced Divs (pandoc, custom)
+  } else if ( match( block, /^(:::+)/ ) ) {
+    guard = substr( block, 1, RLENGTH );
+    code = gensub(/^[^\n]+\n/, "", 1, block);
+    attrib = gensub(/^:::+[ \t]*\{?[ \t]*([^\}\n]*)\}?[ \t]*\n.*$/, "\\1", 1, block);
+    gsub(/[^a-zA-Z0-9_-]+/, " ", attrib);
+    gsub(/(^ | $)/, "", attrib);
+    if ( match(code, "(^|\n)" guard "+(\n|$)" ) ) {
+      len = RLENGTH; st = RSTART;
+      return "<div class=\"" attrib "\">" _block( substr(code, 1, st - 1) ) "</div>\n" \
+             _block( substr( code, st + len ) );
+    } else {
+      match( block, /(^|\n)[[:space:]]*(\n|$)/ ) || match( block, /$/ );
+      len = RLENGTH; st = RSTART;
+      return "<p>" inline( substr(block, 1, st - 1) ) "</p>\n" \
+             _block( substr(block, st + len) );
+    }
+
   # Fenced Code Block (pandoc)
   } else if ( match( block, /^(~~~+|```+)/ ) ) {
     guard = substr( block, 1, RLENGTH );
     code = gensub(/^[^\n]+\n/, "", 1, block);
+    attrib = gensub(/^:::+[ \t]*\{?[ \t]*([^\}\n]*)\}?[ \t]*\n.*$/, "\\1", 1, block);
+    gsub(/[^a-zA-Z0-9_-]+/, " ", attrib);
+    gsub(/(^ | $)/, "", attrib);
     if ( match(code, "(^|\n)" guard "+(\n|$)" ) ) {
       len = RLENGTH; st = RSTART;
-      return "<pre><code>" HTML( substr(code, 1, st - 1) ) "</code></pre>\n" \
+      return "<pre><code class=\"" attrib "\">" HTML( substr(code, 1, st - 1) ) "</code></pre>\n" \
              _block( substr( code, st + len ) );
     } else {
       match( block, /(^|\n)[[:space:]]*(\n|$)/ ) || match( block, /$/ );
@@ -256,29 +378,41 @@ function _block( block, LOCAL, st, len, hlvl, htxt, guard, code, indent ) {
   # First Order Heading
   } else if ( match( block, /^[^\n]+\n===+(\n|$)/ ) ) {
     len = RLENGTH;
-    return "<h1>" inline( gensub( /\n.*$/, "", "g", block ) ) "</h1>\n\n" \
+    HL[1]++; HL[2] = 0; HL[3] = 0; HL[4] = 0; HL[5] = 0; HL[6] = 0;
+    return "<h1 id=\"" HL[1] " - " HTML(gensub( /\n.*$/, "", "g", block )) "\">" inline( gensub( /\n.*$/, "", "g", block ) ) "</h1>\n\n" \
            _block( substr( block, len + 1 ) );
 
   # Second Order Heading
   } else if ( match( block, /^[^\n]+\n---+(\n|$)/ ) ) {
     len = RLENGTH;
-    return "<h2>" inline( gensub( /\n.*$/, "", "g", block ) ) "</h2>\n\n" \
+    HL[2]++; HL[3] = 0; HL[4] = 0; HL[5] = 0; HL[6] = 0;
+    return "<h2 id=\"" HL[1] "." HL[2] " - " HTML(gensub( /\n.*$/, "", "g", block )) "\">" inline( gensub( /\n.*$/, "", "g", block ) ) "</h2>\n\n" \
            _block( substr( block, len + 1) );
 
   # Nth Order Heading
-  } else if ( match( block, /^#{1,6}[[:space:]]*[^\n]+([[:space:]]*#*)(\n|$)/ ) ) {
+  } else if ( match( block, /^#{1,6}[ \t]*[^\n]+([ \t]*#*)(\n|$)/ ) ) {
     len = RLENGTH;
     hlvl = length( gensub( /^(#{1,6}).*$/, "\\1", "g", block ) );
-    htxt = gensub( /[[:space:]]*#*$/, "", "1", gensub( /^#{1,6}[[:space:]]*([^\n]+)([[:space:]]*#*)\n.*$/, "\\1", "g", block ) )
-    return "<h" hlvl ">" inline( htxt ) "</h" hlvl ">\n\n" \
+    htxt = gensub(/^#{1,6}[ \t]*(([^ \t\n]+|[ \t]+[^ \t\n#]|[ \t]+#+[^\n#])+)([ \t]*#*)(\n.*)?$/, "\\1", 1, block);
+    HL[hlvl]++; for ( n = hlvl + 1; n < 7; n++) { HL[n] = 0;}
+    hid = HL[1]; for ( n = 2; n <= hlvl; n++) { hid = hid "." HL[n] ; }
+    return "<h" hlvl " id=\"" hid " - " HTML(htxt) "\">" inline( htxt ) "</h" hlvl ">\n\n" \
            _block( substr( block, len + 1) );
 
-  # Plain paragraph
-  } else {
-    match( block, /(^|\n)[[:space:]]*(\n|$)/ ) || match( block, /$/ );
+  # Split paragraphs
+  } else if ( match( block, /(^|\n)[[:space:]]*(\n|$)/) ) {
     len = RLENGTH; st = RSTART;
-    return "<p>" inline( substr(block, 1, st - 1) ) "</p>\n" \
+    return _block( substr(block, 1, st - 1) ) "\n" \
            _block( substr(block, st + len) );
+
+  # Horizontal rule
+  } else if ( match( block, /(^|\n) ? ? ?((\* *){3,}|(- *){3,}|(_ *){3,})($|\n)/) ) {
+    len = RLENGTH; st = RSTART;
+    return _block(substr(block, 1, st - 1)) "<hr />\n" _block(substr(block, st + len));
+
+  # Plain paragraph
+  } else {
+    return "<p>" inline(block) "</p>\n";
   }
 }
 
@@ -305,15 +439,25 @@ function _list( block, last, LOCAL, p) {
     sub( /<\/p>\n/, "", p );
   }
   sub( /\n$/, "", p );
+
+  # Task List (pandoc)
+       if ( p ~ /^\[ \].*/ )       { p = "<input type=checkbox disabled />" substr(p, 4); }
+  else if ( p ~ /^\[[xX]\].*/ )    { p = "<input type=checkbox disabled checked />" substr(p, 4); }
+  else if ( p ~ /^<p>\[ \].*/ )    { p = "<p><input type=checkbox disabled />" substr(p, 7); }
+  else if ( p ~ /^<p>\[[xX]\].*/ ) { p = "<p><input type=checkbox disabled checked />" substr(p, 7); }
   return "<li>" p "</li>\n" _list( block, last );
 }
 
 BEGIN {
   # Global Vars
   file = ""; rl_href[""] = ""; rl_title[""] = "";
+  if (ENVIRON["MD_HTML"] == "true") { AllowHTML = "true"; }
+  HL[1] = 0; HL[2] = 0; HL[3] = 0; HL[4] = 0; HL[5] = 0; HL[6] = 0;
 
   # Buffering of full file ist necessary, e.g. to find reference links
   while (getline) { file = file $0 "\n"; }
+  # Clean up MS-DOS line breaks
+  gsub(/\r\n/, "\n", file);
 
   # Fill array of reference links
   f = file; rl_id;