Merge pull request #271 from brief/footnotes locally

Add PHP-Markdown style footnotes support

Conflicts:
	test/html_render_test.rb

CHANGELOG.md

@@ -20,6 +20,8 @@
 
 * Ensure nested code spans put in emphasis work correctly *Robin Dupret*
 
+* Add optional footnotes support *Ben Dolman, Adam Florin, microjo, brief*
+
 ## Version 2.3.0
 
 * Add a `:disable_indented_code_blocks` option *Dmitriy Kiriyenko*

README.markdown

@@ -101,6 +101,8 @@ would not be a valid header.
 * `:highlight`: parse highlights.
 `This is ==highlighted==`. It looks like this: `<mark>highlighted</mark>`
 
+* `:footnotes`: parse footnotes, PHP-Markdown style. A footnote works very much like a reference-style link: it consists of a  marker next to the text (e.g. `This is a sentence.[^1]`) and a footnote definition on its own line anywhere within the document (e.g. `[^1]: This is a footnote.`).
+
 Example:
 
 ~~~~~ ruby

ext/redcarpet/html.c

@@ -526,6 +526,60 @@ rndr_normal_text(struct buf *ob, const struct buf *text, void *opaque)
 		escape_html(ob, text->data, text->size);
 }
 
+static void
+rndr_footnotes(struct buf *ob, const struct buf *text, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	if (ob->size) bufputc(ob, '\n');
+
+	BUFPUTSL(ob, "<div class=\"footnotes\">\n");
+	bufputs(ob, USE_XHTML(options) ? "<hr/>\n" : "<hr>\n");
+	BUFPUTSL(ob, "<ol>\n");
+
+	if (text)
+		bufput(ob, text->data, text->size);
+
+	BUFPUTSL(ob, "\n</ol>\n</div>\n");
+}
+
+static void
+rndr_footnote_def(struct buf *ob, const struct buf *text, unsigned int num, void *opaque)
+{
+	size_t i = 0;
+	int pfound = 0;
+
+	/* insert anchor at the end of first paragraph block */
+	if (text) {
+		while ((i+3) < text->size) {
+			if (text->data[i++] != '<') continue;
+			if (text->data[i++] != '/') continue;
+			if (text->data[i++] != 'p' && text->data[i] != 'P') continue;
+			if (text->data[i] != '>') continue;
+			i -= 3;
+			pfound = 1;
+			break;
+		}
+	}
+
+	bufprintf(ob, "\n<li id=\"fn%d\">\n", num);
+	if (pfound) {
+		bufput(ob, text->data, i);
+		bufprintf(ob, "&nbsp;<a href=\"#fnref%d\" rev=\"footnote\">&#8617;</a>", num);
+		bufput(ob, text->data + i, text->size - i);
+	} else if (text) {
+		bufput(ob, text->data, text->size);
+	}
+	BUFPUTSL(ob, "</li>\n");
+}
+
+static int
+rndr_footnote_ref(struct buf *ob, unsigned int num, void *opaque)
+{
+	bufprintf(ob, "<sup id=\"fnref%d\"><a href=\"#fn%d\" rel=\"footnote\">%d</a></sup>", num, num, num);
+	return 1;
+}
+
 static void
 toc_header(struct buf *ob, const struct buf *text, int level, void *opaque)
 {
@@ -594,6 +648,8 @@ sdhtml_toc_renderer(struct sd_callbacks *callbacks, struct html_renderopt *optio
 		NULL,
 		NULL,
 		NULL,
+		rndr_footnotes,
+		rndr_footnote_def,
 
 		NULL,
 		rndr_codespan,
@@ -608,6 +664,7 @@ sdhtml_toc_renderer(struct sd_callbacks *callbacks, struct html_renderopt *optio
 		rndr_triple_emphasis,
 		rndr_strikethrough,
 		rndr_superscript,
+		rndr_footnote_ref,
 
 		NULL,
 		NULL,
@@ -637,6 +694,8 @@ sdhtml_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options,
 		rndr_table,
 		rndr_tablerow,
 		rndr_tablecell,
+		rndr_footnotes,
+		rndr_footnote_def,
 
 		rndr_autolink,
 		rndr_codespan,
@@ -651,6 +710,7 @@ sdhtml_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options,
 		rndr_triple_emphasis,
 		rndr_strikethrough,
 		rndr_superscript,
+		rndr_footnote_ref,
 
 		NULL,
 		rndr_normal_text,