kc3-lang/md4c

diff --git a/md2html/md2html.c b/md2html/md2html.c
index 16f1beb..f631fae 100644
--- a/md2html/md2html.c
+++ b/md2html/md2html.c
@@ -198,6 +198,7 @@ static const option cmdline_options[] = {
     { "fverbatim-entities",          0,  'E', OPTION_ARG_NONE },
     { "fpermissive-atx-headers",     0,  'A', OPTION_ARG_NONE },
     { "fpermissive-url-autolinks",   0,  'U', OPTION_ARG_NONE },
+    { "fpermissive-www-autolinks",   0,  '.', OPTION_ARG_NONE },
     { "fpermissive-email-autolinks", 0,  '@', OPTION_ARG_NONE },
     { "fpermissive-autolinks",       0,  'V', OPTION_ARG_NONE },
     { "fno-indented-code",           0,  'I', OPTION_ARG_NONE },
@@ -238,10 +239,13 @@ usage(void)
         "                       Allow ATX headers without delimiting space\n"
         "      --fpermissive-url-autolinks\n"
         "                       Allow URL autolinks without '<', '>'\n"
+        "      --fpermissive-www-autolinks\n"
+        "                       Allow WWW autolinks without any scheme (e.g. 'www.example.com')\n"
         "      --fpermissive-email-autolinks  \n"
         "                       Allow e-mail autolinks without '<', '>' and 'mailto:'\n"
         "      --fpermissive-autolinks\n"
-        "                       Same as --fpermissive-url-autolinks --fpermissive-email-autolinks\n"
+        "                       Same as --fpermissive-url-autolinks --fpermissive-www-autolinks\n"
+        "                       --fpermissive-email-autolinks\n"
         "      --fno-indented-code\n"
         "                       Disable indented code blocks\n"
         "      --fno-html-blocks\n"
@@ -293,6 +297,7 @@ cmdline_callback(int opt, char const* value, void* data)
         case 'H':   parser_flags |= MD_FLAG_NOHTML; break;
         case 'W':   parser_flags |= MD_FLAG_COLLAPSEWHITESPACE; break;
         case 'U':   parser_flags |= MD_FLAG_PERMISSIVEURLAUTOLINKS; break;
+        case '.':   parser_flags |= MD_FLAG_PERMISSIVEWWWAUTOLINKS; break;
         case '@':   parser_flags |= MD_FLAG_PERMISSIVEEMAILAUTOLINKS; break;
         case 'V':   parser_flags |= MD_FLAG_PERMISSIVEAUTOLINKS; break;
         case 'T':   parser_flags |= MD_FLAG_TABLES; break;
diff --git a/md4c/md4c.c b/md4c/md4c.c
index 3681503..ce7cd8d 100644
--- a/md4c/md4c.c
+++ b/md4c/md4c.c
@@ -2154,8 +2154,9 @@ md_free_link_ref_defs(MD_CTX* ctx)
  *  '[': Maybe start of link label or link text.
  *  '!': Equivalent of '[' for image.
  *  ']': Maybe end of link label or link text.
- *  ':': Maybe permissive URL auto-link (needs MD_FLAG_PERMISSIVEURLAUTOLINKS).
  *  '@': Maybe permissive e-mail auto-link (needs MD_FLAG_PERMISSIVEEMAILAUTOLINKS).
+ *  ':': Maybe permissive URL auto-link (needs MD_FLAG_PERMISSIVEURLAUTOLINKS).
+ *  '.': Maybe permissive WWW auto-link (needs MD_FLAG_PERMISSIVEWWWAUTOLINKS).
  *  'D': Dummy mark, it reserves a space for splitting a previous mark
  *       (e.g. emphasis) or to make more space for storing some special data
  *       related to the preceding mark (e.g. link).
@@ -2414,11 +2415,14 @@ md_build_mark_char_map(MD_CTX* ctx)
     if(ctx->r.flags & MD_FLAG_STRIKETHROUGH)
         ctx->mark_char_map['~'] = 1;
 
+    if(ctx->r.flags & MD_FLAG_PERMISSIVEEMAILAUTOLINKS)
+        ctx->mark_char_map['@'] = 1;
+
     if(ctx->r.flags & MD_FLAG_PERMISSIVEURLAUTOLINKS)
         ctx->mark_char_map[':'] = 1;
 
-    if(ctx->r.flags & MD_FLAG_PERMISSIVEEMAILAUTOLINKS)
-        ctx->mark_char_map['@'] = 1;
+    if(ctx->r.flags & MD_FLAG_PERMISSIVEWWWAUTOLINKS)
+        ctx->mark_char_map['.'] = 1;
 
     if(ctx->r.flags & MD_FLAG_TABLES)
         ctx->mark_char_map['|'] = 1;
@@ -2613,6 +2617,20 @@ md_collect_marks(MD_CTX* ctx, const MD_LINE* lines, int n_lines, int table_mode)
                 continue;
             }
 
+            /* A potential permissive e-mail autolink. */
+            if(ch == _T('@')) {
+                if(line->beg + 1 <= off  &&  ISALNUM(off-1)  &&
+                    off + 3 < line->end  &&  ISALNUM(off+1))
+                {
+                    PUSH_MARK(ch, off, off+1, MD_MARK_POTENTIAL_OPENER);
+                    /* Push a dummy as a reserve for a closer. */
+                    PUSH_MARK('D', off, off, 0);
+                }
+
+                off++;
+                continue;
+            }
+
             /* A potential permissive URL autolink. */
             if(ch == _T(':')) {
                 static struct {
@@ -2624,8 +2642,7 @@ md_collect_marks(MD_CTX* ctx, const MD_LINE* lines, int n_lines, int table_mode)
                     /* In the order from the most frequently used, arguably. */
                     { _T("http"), 4,    _T("//"), 2 },
                     { _T("https"), 5,   _T("//"), 2 },
-                    { _T("mailto"), 6,  NULL, 0 },
-                    { _T("ftp"), 3,     _T("//"), 2 },
+                    { _T("ftp"), 3,     _T("//"), 2 }
                 };
                 int scheme_index;
 
@@ -2636,7 +2653,7 @@ md_collect_marks(MD_CTX* ctx, const MD_LINE* lines, int n_lines, int table_mode)
                     const SZ suffix_size = scheme_map[scheme_index].suffix_size;
 
                     if(line->beg + scheme_size <= off  &&  md_ascii_eq(STR(off-scheme_size), scheme, scheme_size)  &&
-                        (line->beg + scheme_size == off || ISWHITESPACE(off-scheme_size-1))  &&
+                        (line->beg + scheme_size == off || ISWHITESPACE(off-scheme_size-1) || ISANYOF(off-scheme_size-1, _T("*_~([")))  &&
                         off + 1 + suffix_size < line->end  &&  md_ascii_eq(STR(off+1), suffix, suffix_size))
                     {
                         PUSH_MARK(ch, off-scheme_size, off+1+suffix_size, MD_MARK_POTENTIAL_OPENER);
@@ -2651,14 +2668,17 @@ md_collect_marks(MD_CTX* ctx, const MD_LINE* lines, int n_lines, int table_mode)
                 continue;
             }
 
-            /* A potential permissive e-mail autolink. */
-            if(ch == _T('@')) {
-                if(line->beg + 1 <= off  &&  ISALNUM(off-1)  &&
-                    off + 3 < line->end  &&  ISALNUM(off+1))
+            /* A potential permissive WWW autolink. */
+            if(ch == _T('.')) {
+                if(line->beg + 3 <= off  &&  md_ascii_eq(STR(off-3), _T("www"), 3)  &&
+                    (line->beg + 3 == off || ISWHITESPACE(off-4) || ISANYOF(off-4, _T("*_~([")))  &&
+                    off + 1 < line_end)
                 {
-                    PUSH_MARK(ch, off, off+1, MD_MARK_POTENTIAL_OPENER);
+                    PUSH_MARK(ch, off-3, off+1, MD_MARK_POTENTIAL_OPENER);
                     /* Push a dummy as a reserve for a closer. */
                     PUSH_MARK('D', off, off, 0);
+                    off++;
+                    continue;
                 }
 
                 off++;
@@ -3285,38 +3305,63 @@ static void
 md_analyze_permissive_url_autolink(MD_CTX* ctx, int mark_index)
 {
     MD_MARK* opener = &ctx->marks[mark_index];
-    int closer_index;
-    MD_MARK* closer;
+    int closer_index = mark_index + 1;
+    MD_MARK* closer = &ctx->marks[mark_index + 1];
+    MD_MARK* next_resolved_mark;
     OFF off = opener->end;
+    int seen_dot = FALSE;
+    int seen_underscore_or_hyphen[2] = { FALSE, FALSE };
 
-    if(off < ctx->size && ISALNUM(off))
-        off++;
-    else
+    /* Check for domain. */
+    while(off < ctx->size) {
+        if(ISALNUM(off)) {
+            off++;
+        } else if(CH(off) == _T('.')) {
+            seen_dot = TRUE;
+            seen_underscore_or_hyphen[0] = seen_underscore_or_hyphen[1];
+            seen_underscore_or_hyphen[1] = FALSE;
+            off++;
+        } else if(ISANYOF2(off, _T('-'), _T('_'))) {
+            seen_underscore_or_hyphen[1] = TRUE;
+            off++;
+        } else {
+            break;
+        }
+    }
+
+    if(off <= opener->end || !seen_dot || seen_underscore_or_hyphen[0] || seen_underscore_or_hyphen[1])
         return;
 
-    while(1) {
-        while(off < ctx->size && (ISALNUM(off) || CH(off) == _T('/')))
-            off++;
+    /* Check for path. */
+    next_resolved_mark = closer + 1;
+    while(next_resolved_mark->ch == 'D' || !(next_resolved_mark->flags & MD_MARK_RESOLVED))
+        next_resolved_mark++;
+    while(off < next_resolved_mark->beg  &&  CH(off) != _T('<')  &&  !ISWHITESPACE(off)  &&  !ISNEWLINE(off))
+        off++;
 
-        /* We need to be relatively careful to not include too much into the URL.
-         * Consider e.g. a dot or question mark:
-         *   "Go to http://example.com." versus "http://example.com.uk"
-         *   "Do you know http://zombo.com?" versus "http://example.com/?page=2"
-         * Therefore we include some named punctuation characters only if they
-         * are immediately followed by alnum char.
-         */
-        if(off + 1 < ctx->size && ISANYOF(off, _T("@.?=&%+-_#")) && ISALNUM(off+1))
-            off += 2;
-        else
-            break;
+    /* Path validation. */
+    if(ISANYOF(off-1, _T("?!.,:*_~)"))) {
+        if(CH(off-1) != _T(')')) {
+            off--;
+        } else {
+            int parenthesis_balance = 0;
+            OFF tmp;
+
+            for(tmp = opener->end; tmp < off; tmp++) {
+                if(CH(tmp) == _T('('))
+                    parenthesis_balance++;
+                else if(CH(tmp) == _T(')'))
+                    parenthesis_balance--;
+            }
+
+            if(parenthesis_balance < 0)
+                off--;
+        }
     }
 
     /* Ok. Lets call it auto-link. Adapt opener and create closer to zero
      * length so all the contents becomes the link text. */
-    closer_index = mark_index + 1;
-    closer = &ctx->marks[closer_index];
     MD_ASSERT(closer->ch == 'D');
-
     opener->end = opener->beg;
     closer->ch = opener->ch;
     closer->beg = off;
@@ -3436,6 +3481,7 @@ md_analyze_marks(MD_CTX* ctx, const MD_LINE* lines, int n_lines, OFF beg, OFF en
             case '*':   md_analyze_asterisk(ctx, i); break;
             case '_':   md_analyze_underscore(ctx, i); break;
             case '~':   md_analyze_tilde(ctx, i); break;
+            case '.':   /* Pass through. */
             case ':':   md_analyze_permissive_url_autolink(ctx, i); break;
             case '@':   md_analyze_permissive_email_autolink(ctx, i); break;
         }
@@ -3494,7 +3540,7 @@ abort:
 static void
 md_analyze_link_contents(MD_CTX* ctx, const MD_LINE* lines, int n_lines, OFF beg, OFF end)
 {
-    md_analyze_marks(ctx, lines, n_lines, beg, end, _T("*_~@:"));
+    md_analyze_marks(ctx, lines, n_lines, beg, end, _T("*_~@:."));
     ASTERISK_OPENERS.head = -1;
     ASTERISK_OPENERS.tail = -1;
     UNDERSCORE_OPENERS.head = -1;
@@ -3645,16 +3691,19 @@ md_process_inlines(MD_CTX* ctx, const MD_LINE* lines, int n_lines)
 
                 case '@':       /* Permissive e-mail autolink. */
                 case ':':       /* Permissive URL autolink. */
+                case '.':       /* Permissive WWW autolink. */
                 {
                     const MD_MARK* opener = ((mark->flags & MD_MARK_OPENER) ? mark : &ctx->marks[mark->prev]);
                     const MD_MARK* closer = &ctx->marks[opener->next];
                     const CHAR* dest = STR(opener->end);
                     SZ dest_size = closer->beg - opener->end;
 
-                    if(opener->ch == '@') {
+                    if(opener->ch == '@' || opener->ch == '.') {
                         dest_size += 7;
                         MD_TEMP_BUFFER(dest_size * sizeof(CHAR));
-                        memcpy(ctx->buffer, _T("mailto:"), 7 * sizeof(CHAR));
+                        memcpy(ctx->buffer,
+                                (opener->ch == '@' ? _T("mailto:") : _T("http://")),
+                                7 * sizeof(CHAR));
                         memcpy(ctx->buffer + 7, dest, (dest_size-7) * sizeof(CHAR));
                         dest = ctx->buffer;
                     }
diff --git a/md4c/md4c.h b/md4c/md4c.h
index a58cc74..cd578ca 100644
--- a/md4c/md4c.h
+++ b/md4c/md4c.h
@@ -262,13 +262,15 @@ typedef struct MD_SPAN_IMG_DETAIL {
 #define MD_FLAG_PERMISSIVEATXHEADERS        0x0002  /* Do not require space in ATX headers ( ###header ) */
 #define MD_FLAG_PERMISSIVEURLAUTOLINKS      0x0004  /* Recognize URLs as autolinks even without '<', '>' */
 #define MD_FLAG_PERMISSIVEEMAILAUTOLINKS    0x0008  /* Recognize e-mails as autolinks even without '<', '>' and 'mailto:' */
-#define MD_FLAG_PERMISSIVEAUTOLINKS         (MD_FLAG_PERMISSIVEURLAUTOLINKS | MD_FLAG_PERMISSIVEEMAILAUTOLINKS)
 #define MD_FLAG_NOINDENTEDCODEBLOCKS        0x0010  /* Disable indented code blocks. (Only fenced code works.) */
 #define MD_FLAG_NOHTMLBLOCKS                0x0020  /* Disable raw HTML blocks. */
 #define MD_FLAG_NOHTMLSPANS                 0x0040  /* Disable raw HTML (inline). */
-#define MD_FLAG_NOHTML                      (MD_FLAG_NOHTMLBLOCKS | MD_FLAG_NOHTMLSPANS)
 #define MD_FLAG_TABLES                      0x0100  /* Enable tables extension. */
 #define MD_FLAG_STRIKETHROUGH               0x0200  /* Enable strikethrough extension. */
+#define MD_FLAG_PERMISSIVEWWWAUTOLINKS      0x0400  /* Enable WWW autolinks (even without any scheme prefix, if they begin with 'www.') */
+
+#define MD_FLAG_PERMISSIVEAUTOLINKS         (MD_FLAG_PERMISSIVEEMAILAUTOLINKS | MD_FLAG_PERMISSIVEURLAUTOLINKS | MD_FLAG_PERMISSIVEWWWAUTOLINKS)
+#define MD_FLAG_NOHTML                      (MD_FLAG_NOHTMLBLOCKS | MD_FLAG_NOHTMLSPANS)
 
 /* Convenient sets of flags corresponding to well-known Markdown dialects.
  * Note we may only support subset of features of the referred dialect.
diff --git a/scripts/run-tests.sh b/scripts/run-tests.sh
index 8dd42be..72bc75c 100755
--- a/scripts/run-tests.sh
+++ b/scripts/run-tests.sh
@@ -34,5 +34,6 @@ $PYTHON "$TEST_DIR/spec_tests.py" -s "$TEST_DIR/coverage.txt" -p "$PROGRAM"
 # Test various extensions and deviations from the specifications:
 $PYTHON "$TEST_DIR/spec_tests.py" -s "$TEST_DIR/permissive-email-autolinks.txt" -p "$PROGRAM --fpermissive-email-autolinks"
 $PYTHON "$TEST_DIR/spec_tests.py" -s "$TEST_DIR/permissive-url-autolinks.txt" -p "$PROGRAM --fpermissive-url-autolinks"
+$PYTHON "$TEST_DIR/spec_tests.py" -s "$TEST_DIR/permissive-www-autolinks.txt" -p "$PROGRAM --fpermissive-www-autolinks"
 $PYTHON "$TEST_DIR/spec_tests.py" -s "$TEST_DIR/tables.txt" -p "$PROGRAM --ftables"
 $PYTHON "$TEST_DIR/spec_tests.py" -s "$TEST_DIR/strikethrough.txt" -p "$PROGRAM --fstrikethrough"
diff --git a/test/permissive-url-autolinks.txt b/test/permissive-url-autolinks.txt
index 4b42f95..000a86f 100644
--- a/test/permissive-url-autolinks.txt
+++ b/test/permissive-url-autolinks.txt
@@ -22,8 +22,7 @@ Homepage: https://github.com/mity/md4c
 ````````````````````````````````
 
 But this permissive autolink feature can work only for very widely used URL
-schemes, in alphabetical order `ftp:`, `http:`, `https:` and `mailto:`,
-so this is not an permissive autolink.
+schemes, in alphabetical order `ftp:`, `http:`, `https:`.
 
 That's why this is not a permissive autolink:
 
@@ -33,12 +32,8 @@ ssh://root@example.com
 <p>ssh://root@example.com</p>
 ````````````````````````````````
 
-As certain characters (`.`, `?`, `=`, `&`, `%`, `+`, `-`, `_`, `#`, `@`) can collide
-with a normal text flow, they are not recognized as part of the URL unless another
-alphanumeric character immediately follows.
-
-Therefore the question mark in this question is not part of the autolink's
-contents:
+The same rules for path validation as for permissivve WWW autolinks apply.
+Therefore the final question mark here is not part of the autolink:
 
 ```````````````````````````````` example
 Have you ever visited http://www.zombo.com?
@@ -54,19 +49,16 @@ http://www.bing.com/search?q=md4c
 <p><a href="http://www.bing.com/search?q=md4c">http://www.bing.com/search?q=md4c</a></p>
 ````````````````````````````````
 
-Please note that e-mail addresses without the `mailto:` scheme are not permissive URL
-autolinks, but MD4C implements another extension `MD_FLAG_PERMISSIVEEMAILAUTOLINKS`
-which can be used to enable that too.
+And finally one complex example:
 
 ```````````````````````````````` example
-mailto:john.doe@example.com
-.
-<p><a href="mailto:john.doe@example.com">mailto:john.doe@example.com</a></p>
-````````````````````````````````
+http://commonmark.org
 
-```````````````````````````````` example
-john.doe@example.com
+(Visit https://encrypted.google.com/search?q=Markup+(business))
+
+Anonymous FTP is available at ftp://foo.bar.baz.
 .
-<p>john.doe@example.com</p>
+<p><a href="http://commonmark.org">http://commonmark.org</a></p>
+<p>(Visit <a href="https://encrypted.google.com/search?q=Markup+(business)">https://encrypted.google.com/search?q=Markup+(business)</a>)</p>
+<p>Anonymous FTP is available at <a href="ftp://foo.bar.baz">ftp://foo.bar.baz</a>.</p>
 ````````````````````````````````
-
diff --git a/test/permissive-www-autolinks.txt b/test/permissive-www-autolinks.txt
new file mode 100644
index 0000000..ec076c3
--- /dev/null
+++ b/test/permissive-www-autolinks.txt
@@ -0,0 +1,92 @@
+
+# Permissive WWW Autolinks
+
+With the flag `MD_FLAG_PERMISSIVEWWWAUTOLINKS`, MD4C enables recognition of
+autolinks starting with `www.`, even if they do not exactly follow the syntax
+of autolink as specified in CommonMark specification.
+
+These do not have to be enclosed in `<` and `>`, and they even do not need
+any preceding scheme specification.
+
+The WWW autolink will be recognized when a valid domain is found.
+
+A valid domain consists of the text `www.`, followed by alphanumeric characters,
+nderscores (`_`), hyphens (`-`) and periods (`.`). There must be at least one
+period, and no underscores may be present in the last two segments of the domain.
+
+The scheme `http` will be inserted automatically:
+
+```````````````````````````````` example
+www.commonmark.org
+.
+<p><a href="http://www.commonmark.org">www.commonmark.org</a></p>
+````````````````````````````````
+
+After a valid domain, zero or more non-space non-`<` characters may follow:
+
+```````````````````````````````` example
+Visit www.commonmark.org/help for more information.
+.
+<p>Visit <a href="http://www.commonmark.org/help">www.commonmark.org/help</a> for more information.</p>
+````````````````````````````````
+
+We then apply extended autolink path validation as follows:
+
+Trailing punctuation (specifically, `?`, `!`, `.`, `,`, `:`, `*`, `_`, and `~`)
+will not be considered part of the autolink, though they may be included in the
+interior of the link:
+
+```````````````````````````````` example
+Visit www.commonmark.org.
+
+Visit www.commonmark.org/a.b.
+.
+<p>Visit <a href="http://www.commonmark.org">www.commonmark.org</a>.</p>
+<p>Visit <a href="http://www.commonmark.org/a.b">www.commonmark.org/a.b</a>.</p>
+````````````````````````````````
+
+When an autolink ends in `)`, we scan the entire autolink for the total number
+of parentheses.  If there is a greater number of closing parentheses than
+opening ones, we don't consider the last character part of the autolink, in
+order to facilitate including an autolink inside a parenthesis:
+
+```````````````````````````````` example
+www.google.com/search?q=Markup+(business)
+
+(www.google.com/search?q=Markup+(business))
+.
+<p><a href="http://www.google.com/search?q=Markup+(business)">www.google.com/search?q=Markup+(business)</a></p>
+<p>(<a href="http://www.google.com/search?q=Markup+(business)">www.google.com/search?q=Markup+(business)</a>)</p>
+````````````````````````````````
+
+This check is only done when the link ends in a closing parentheses `)`, so if
+the only parentheses are in the interior of the autolink, no special rules are
+applied:
+
+```````````````````````````````` example
+www.google.com/search?q=(business))+ok
+.
+<p><a href="http://www.google.com/search?q=(business))+ok">www.google.com/search?q=(business))+ok</a></p>
+````````````````````````````````
+
+If an autolink ends in a semicolon (`;`), we check to see if it appears to
+resemble an [entity reference][entity references]; if the preceding text is `&`
+followed by one or more alphanumeric characters.  If so, it is excluded from
+the autolink:
+
+```````````````````````````````` example
+www.google.com/search?q=commonmark&hl=en
+
+www.google.com/search?q=commonmark&hl;
+.
+<p><a href="http://www.google.com/search?q=commonmark&hl=en">www.google.com/search?q=commonmark&amp;hl=en</a></p>
+<p><a href="http://www.google.com/search?q=commonmark">www.google.com/search?q=commonmark</a>&amp;hl;</p>
+````````````````````````````````
+
+`<` immediately ends an autolink.
+
+```````````````````````````````` example
+www.commonmark.org/he<lp
+.
+<p><a href="http://www.commonmark.org/he">www.commonmark.org/he</a>&lt;lp</p>
+````````````````````````````````