optionally allow Reddit-style spoiler delimiters

QuietMisdreavus · QuietMisdreavus · commit dce9a9b973fb · 2021-12-29T12:28:56.000-07:00
diff --git a/api_test/main.c b/api_test/main.c
@@ -1455,6 +1455,74 @@ static void render_spoiler(test_batch_runner *runner) {
            "  </paragraph>\n"
            "</document>\n", "rendering spoilers without proper delimiters should appear correctly");
   }
+  {
+    static const char markdown[] = "we have some >!incorrectly spicy text!< here";
+    cmark_parser_feed(parser, markdown, sizeof(markdown) - 1);
+
+    cmark_node *doc = cmark_parser_finish(parser);
+    char *xml = cmark_render_xml(doc, CMARK_OPT_DEFAULT);
+    STR_EQ(runner, xml, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+           "<!DOCTYPE document SYSTEM \"CommonMark.dtd\">\n"
+           "<document xmlns=\"http://commonmark.org/xml/1.0\">\n"
+           "  <paragraph>\n"
+           "    <text xml:space=\"preserve\">we have some &gt;!incorrectly spicy text!&lt; here</text>\n"
+           "  </paragraph>\n"
+           "</document>\n", "rendering spoilers without proper delimiters should appear correctly");
+  }
+}
+
+static void render_spoiler_reddit(test_batch_runner *runner) {
+  cmark_gfm_core_extensions_ensure_registered();
+
+  cmark_parser *parser = cmark_parser_new(CMARK_OPT_SPOILER_REDDIT_STYLE);
+  cmark_parser_attach_syntax_extension(parser, cmark_find_syntax_extension("spoiler"));
+
+  {
+    static const char markdown[] = "we have some >!spicy text!< here";
+    cmark_parser_feed(parser, markdown, sizeof(markdown) - 1);
+
+    cmark_node *doc = cmark_parser_finish(parser);
+    char *xml = cmark_render_xml(doc, CMARK_OPT_DEFAULT);
+    STR_EQ(runner, xml, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+           "<!DOCTYPE document SYSTEM \"CommonMark.dtd\">\n"
+           "<document xmlns=\"http://commonmark.org/xml/1.0\">\n"
+           "  <paragraph>\n"
+           "    <text xml:space=\"preserve\">we have some </text>\n"
+           "    <spoiler>\n"
+           "      <text xml:space=\"preserve\">spicy text</text>\n"
+           "    </spoiler>\n"
+           "    <text xml:space=\"preserve\"> here</text>\n"
+           "  </paragraph>\n"
+           "</document>\n", "rendering spoilers should appear correctly");
+  }
+  {
+    static const char markdown[] = "we have some !non-spicy text! here";
+    cmark_parser_feed(parser, markdown, sizeof(markdown) - 1);
+
+    cmark_node *doc = cmark_parser_finish(parser);
+    char *xml = cmark_render_xml(doc, CMARK_OPT_DEFAULT);
+    STR_EQ(runner, xml, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+           "<!DOCTYPE document SYSTEM \"CommonMark.dtd\">\n"
+           "<document xmlns=\"http://commonmark.org/xml/1.0\">\n"
+           "  <paragraph>\n"
+           "    <text xml:space=\"preserve\">we have some !non-spicy text! here</text>\n"
+           "  </paragraph>\n"
+           "</document>\n", "rendering spoilers without proper delimiters should appear correctly");
+  }
+  {
+    static const char markdown[] = "we have some ||incorrectly spicy text|| here";
+    cmark_parser_feed(parser, markdown, sizeof(markdown) - 1);
+
+    cmark_node *doc = cmark_parser_finish(parser);
+    char *xml = cmark_render_xml(doc, CMARK_OPT_DEFAULT);
+    STR_EQ(runner, xml, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+           "<!DOCTYPE document SYSTEM \"CommonMark.dtd\">\n"
+           "<document xmlns=\"http://commonmark.org/xml/1.0\">\n"
+           "  <paragraph>\n"
+           "    <text xml:space=\"preserve\">we have some ||incorrectly spicy text|| here</text>\n"
+           "  </paragraph>\n"
+           "</document>\n", "rendering spoilers without proper delimiters should appear correctly");
+  }
 }
 
 int main() {
diff --git a/bin/main.c b/bin/main.c
@@ -64,6 +64,9 @@ void print_usage() {
          "                                  instead of align attributes.\n");
   printf("  --full-info-string              Include remainder of code block info\n"
          "                                  string in a separate attribute.\n");
+  printf("  --spoiler-reddit-style          Use Reddit-style spoiler delimiters,\n"
+         "                                  i.e. >!spoilertext!< instead of\n"
+         "                                  ||spoilertext||\n");
   printf("  --help, -h       Print usage information\n");
   printf("  --version        Print version\n");
 }
@@ -185,6 +188,8 @@ int main(int argc, char *argv[]) {
       options |= CMARK_OPT_VALIDATE_UTF8;
     } else if (strcmp(argv[i], "--liberal-html-tag") == 0) {
       options |= CMARK_OPT_LIBERAL_HTML_TAG;
+    } else if (strcmp(argv[i], "--spoiler-reddit-style") == 0) {
+      options |= CMARK_OPT_SPOILER_REDDIT_STYLE;
     } else if ((strcmp(argv[i], "--help") == 0) ||
                (strcmp(argv[i], "-h") == 0)) {
       print_usage();
diff --git a/extensions/spoiler.c b/extensions/spoiler.c
@@ -11,25 +11,74 @@ static cmark_node *match(cmark_syntax_extension *self, cmark_parser *parser,
   int left_flanking, right_flanking, punct_before, punct_after, delims;
   char buffer[101];
 
-  if (character != '|')
-    return NULL;
-
-  delims = cmark_inline_parser_scan_delimiters(
-      inline_parser, sizeof(buffer) - 1, '|',
-      &left_flanking,
-      &right_flanking, &punct_before, &punct_after);
-
-  memset(buffer, '|', delims);
-  buffer[delims] = 0;
-
-  res = cmark_node_new_with_mem(CMARK_NODE_TEXT, parser->mem);
-  cmark_node_set_literal(res, buffer);
-  res->start_line = res->end_line = cmark_inline_parser_get_line(inline_parser);
-  res->start_column = cmark_inline_parser_get_column(inline_parser) - delims;
-
-  if ((left_flanking || right_flanking) && (delims == 2)) {
-    cmark_inline_parser_push_delimiter(inline_parser, character, left_flanking,
-                                       right_flanking, res);
+  if ((parser->options & CMARK_OPT_SPOILER_REDDIT_STYLE)) {
+    // Reddit-style spoilers - flanked by angle brackets and exclamation marks,
+    // e.g. >!this is a spoiler!<
+    int pos = cmark_inline_parser_get_offset(inline_parser);
+    char *txt = NULL;
+    bool opener = false;
+    bool closer = false;
+    if (cmark_inline_parser_peek_at(inline_parser, pos) == '>' &&
+        cmark_inline_parser_peek_at(inline_parser, pos + 1) == '!') {
+      txt = ">!";
+      opener = true;
+    } else if (cmark_inline_parser_peek_at(inline_parser, pos) == '!' &&
+               cmark_inline_parser_peek_at(inline_parser, pos + 1) == '<') {
+      txt = "!<";
+      closer = true;
+    }
+
+    if (opener && pos > 0 && !cmark_isspace(cmark_inline_parser_peek_at(inline_parser, pos - 1))) {
+      opener = false;
+    }
+
+    if (closer) {
+      cmark_chunk *chunk = cmark_inline_parser_get_chunk(inline_parser);
+      bufsize_t len = chunk->len;
+      if (pos + 2 < len && !cmark_isspace(cmark_inline_parser_peek_at(inline_parser, pos + 2))) {
+        closer = false;
+      }
+    }
+
+    if ((!opener && !closer) || !txt)
+      return NULL;
+
+    res = cmark_node_new_with_mem(CMARK_NODE_TEXT, parser->mem);
+    cmark_node_set_literal(res, txt);
+    res->start_line = cmark_inline_parser_get_line(inline_parser);
+    res->start_column = cmark_inline_parser_get_column(inline_parser);
+
+    cmark_inline_parser_set_offset(inline_parser, pos + 2);
+
+    res->end_line = cmark_inline_parser_get_line(inline_parser);
+    res->end_column = cmark_inline_parser_get_column(inline_parser);
+
+    // Set the character for this delimiter to `!`, since it's a heterogenous
+    // delimiter and the delimiter API assumes single repeated characters.
+    cmark_inline_parser_push_delimiter(inline_parser, '!', opener, closer, res);
+  } else {
+    // Discord-style spoilers - flanked on both sides by two pipes,
+    // e.g. ||this is a spoiler||
+    if (character != '|')
+      return NULL;
+
+    delims = cmark_inline_parser_scan_delimiters(
+        inline_parser, sizeof(buffer) - 1, '|',
+        &left_flanking,
+        &right_flanking, &punct_before, &punct_after);
+
+    memset(buffer, '|', delims);
+    buffer[delims] = 0;
+
+    res = cmark_node_new_with_mem(CMARK_NODE_TEXT, parser->mem);
+    cmark_node_set_literal(res, buffer);
+    res->start_line = res->end_line = cmark_inline_parser_get_line(inline_parser);
+    res->start_column = cmark_inline_parser_get_column(inline_parser) - delims;
+
+    if ((left_flanking || right_flanking) && (delims == 2)) {
+      cmark_inline_parser_push_delimiter(inline_parser, character, left_flanking,
+                                         right_flanking, res);
+    }
   }
 
   return res;
@@ -95,7 +144,16 @@ static int can_contain(cmark_syntax_extension *extension, cmark_node *node,
 static void commonmark_render(cmark_syntax_extension *extension,
                               cmark_renderer *renderer, cmark_node *node,
                               cmark_event_type ev_type, int options) {
-  renderer->out(renderer, node, "||", false, LITERAL);
+  if (options & CMARK_OPT_SPOILER_REDDIT_STYLE) {
+    bool entering = (ev_type == CMARK_EVENT_ENTER);
+    if (entering) {
+      renderer->out(renderer, node, ">!", false, LITERAL);
+    } else {
+      renderer->out(renderer, node, "!<", false, LITERAL);
+    }
+  } else {
+    renderer->out(renderer, node, "||", false, LITERAL);
+  }
 }
 
 static void html_render(cmark_syntax_extension *extension,
@@ -109,12 +167,6 @@ static void html_render(cmark_syntax_extension *extension,
   }
 }
 
-static void plaintext_render(cmark_syntax_extension *extension,
-                             cmark_renderer *renderer, cmark_node *node,
-                             cmark_event_type ev_type, int options) {
-  renderer->out(renderer, node, "~", false, LITERAL);
-}
-
 cmark_syntax_extension *create_spoiler_extension(void) {
   cmark_syntax_extension *ext = cmark_syntax_extension_new("spoiler");
   cmark_llist *special_chars = NULL;
@@ -123,14 +175,17 @@ cmark_syntax_extension *create_spoiler_extension(void) {
   cmark_syntax_extension_set_can_contain_func(ext, can_contain);
   cmark_syntax_extension_set_commonmark_render_func(ext, commonmark_render);
   cmark_syntax_extension_set_html_render_func(ext, html_render);
-  cmark_syntax_extension_set_plaintext_render_func(ext, plaintext_render);
+  cmark_syntax_extension_set_plaintext_render_func(ext, commonmark_render);
   CMARK_NODE_SPOILER = cmark_syntax_extension_add_node(1);
 
   cmark_syntax_extension_set_match_inline_func(ext, match);
   cmark_syntax_extension_set_inline_from_delim_func(ext, insert);
 
   cmark_mem *mem = cmark_get_default_mem_allocator();
   special_chars = cmark_llist_append(mem, special_chars, (void *)'|');
+  special_chars = cmark_llist_append(mem, special_chars, (void *)'>');
+  special_chars = cmark_llist_append(mem, special_chars, (void *)'<');
+  special_chars = cmark_llist_append(mem, special_chars, (void *)'!');
   cmark_syntax_extension_set_special_inline_chars(ext, special_chars);
 
   cmark_syntax_extension_set_emphasis(ext, 1);
diff --git a/src/include/cmark-gfm.h b/src/include/cmark-gfm.h
@@ -780,6 +780,11 @@ char *cmark_render_latex_with_mem(cmark_node *root, int options, int width, cmar
  */
 #define CMARK_OPT_PRESERVE_WHITESPACE ((1 << 19) | CMARK_OPT_INLINE_ONLY)
 
+/** Parse spoiler text with Reddit-style delimiters (`>!this is a spoiler!<`). Without
+ * this option, spoilers are parsed with Discord-style delimiters (`||this is a spoiler||`).
+ */
+#define CMARK_OPT_SPOILER_REDDIT_STYLE (1 << 20)
+
 /**
  * ## Version information
  */
diff --git a/test/spec.txt b/test/spec.txt
@@ -7752,6 +7752,15 @@ Spoiler alert: ||Hello, world!||
 <p>Spoiler alert: <span class="spoiler">Hello, world!</span></p>
 ````````````````````````````````
 
+The `spoiler` extension also optionally allows alternate "Reddit-style" delimiters,
+which use angle brackets and exclamation marks to mark spoiler text:
+
+```````````````````````````````` example disabled
+Spoiler alert: >!Hello, world!!<
+.
+<p>Spoiler alert: <span class="spoiler">Hello, world!</span></p>
+````````````````````````````````
+
 </div>
 
 ## Links
