M block.go → block.go

@@ -13,7 +13,10 @@ //
 
 package blackfriday
 
-import "bytes"
+import (
+	"bytes"
+	"unicode"
+)
 
 // Parse block-level data.
 // Note: this function and many that it calls assume that
@@ -223,6 +226,9 @@ for end > 0 && data[end-1] == ' ' {
 		end--
 	}
 	if end > i {
+		if id == "" && p.flags&EXTENSION_AUTO_HEADER_IDS != 0 {
+			id = createSanitizedAnchorName(string(data[i:end]))
+		}
 		work := func() bool {
 			p.inline(out, data[i:end])
 			return true
@@ -1267,7 +1273,13 @@ pp.inline(o, d)
 						return true
 					}
 				}(out, p, data[prev:eol])
-				p.r.Header(out, work, level, "")
+
+				id := ""
+				if p.flags&EXTENSION_AUTO_HEADER_IDS != 0 {
+					id = createSanitizedAnchorName(string(data[prev:eol]))
+				}
+
+				p.r.Header(out, work, level, id)
 
 				// find the end of the underline
 				for data[i] != '\n' {
@@ -1313,3 +1325,16 @@ 
 	p.renderParagraph(out, data[:i])
 	return i
 }
+
+func createSanitizedAnchorName(text string) string {
+	var anchorName []rune
+	for _, r := range []rune(text) {
+		switch {
+		case r == ' ':
+			anchorName = append(anchorName, '-')
+		case unicode.IsLetter(r) || unicode.IsNumber(r):
+			anchorName = append(anchorName, unicode.ToLower(r))
+		}
+	}
+	return string(anchorName)
+}

M block_test.go → block_test.go

@@ -237,6 +237,48 @@ }
 	doTestsBlock(t, tests, EXTENSION_HEADER_IDS)
 }
 
+func TestPrefixAutoHeaderIdExtension(t *testing.T) {
+	var tests = []string{
+		"# Header 1\n",
+		"<h1 id=\"header-1\">Header 1</h1>\n",
+
+		"# Header 1   \n",
+		"<h1 id=\"header-1\">Header 1</h1>\n",
+
+		"## Header 2\n",
+		"<h2 id=\"header-2\">Header 2</h2>\n",
+
+		"### Header 3\n",
+		"<h3 id=\"header-3\">Header 3</h3>\n",
+
+		"#### Header 4\n",
+		"<h4 id=\"header-4\">Header 4</h4>\n",
+
+		"##### Header 5\n",
+		"<h5 id=\"header-5\">Header 5</h5>\n",
+
+		"###### Header 6\n",
+		"<h6 id=\"header-6\">Header 6</h6>\n",
+
+		"####### Header 7\n",
+		"<h6 id=\"-header-7\"># Header 7</h6>\n",
+
+		"Hello\n# Header 1\nGoodbye\n",
+		"<p>Hello</p>\n\n<h1 id=\"header-1\">Header 1</h1>\n\n<p>Goodbye</p>\n",
+
+		"* List\n# Header\n* List\n",
+		"<ul>\n<li><p>List</p>\n\n<h1 id=\"header\">Header</h1></li>\n\n<li><p>List</p></li>\n</ul>\n",
+
+		"* List\n#Header\n* List\n",
+		"<ul>\n<li><p>List</p>\n\n<h1 id=\"header\">Header</h1></li>\n\n<li><p>List</p></li>\n</ul>\n",
+
+		"*   List\n    * Nested list\n    # Nested header\n",
+		"<ul>\n<li><p>List</p>\n\n<ul>\n<li><p>Nested list</p>\n\n" +
+			"<h1 id=\"nested-header\">Nested header</h1></li>\n</ul></li>\n</ul>\n",
+	}
+	doTestsBlock(t, tests, EXTENSION_AUTO_HEADER_IDS)
+}
+
 func TestUnderlineHeaders(t *testing.T) {
 	var tests = []string{
 		"Header 1\n========\n",
@@ -285,6 +327,50 @@ "Double underline\n=====\n=====\n",
 		"<h1>Double underline</h1>\n\n<p>=====</p>\n",
 	}
 	doTestsBlock(t, tests, 0)
+}
+
+func TestUnderlineHeadersAutoIDs(t *testing.T) {
+	var tests = []string{
+		"Header 1\n========\n",
+		"<h1 id=\"header-1\">Header 1</h1>\n",
+
+		"Header 2\n--------\n",
+		"<h2 id=\"header-2\">Header 2</h2>\n",
+
+		"A\n=\n",
+		"<h1 id=\"a\">A</h1>\n",
+
+		"B\n-\n",
+		"<h2 id=\"b\">B</h2>\n",
+
+		"Paragraph\nHeader\n=\n",
+		"<p>Paragraph</p>\n\n<h1 id=\"header\">Header</h1>\n",
+
+		"Header\n===\nParagraph\n",
+		"<h1 id=\"header\">Header</h1>\n\n<p>Paragraph</p>\n",
+
+		"Header\n===\nAnother header\n---\n",
+		"<h1 id=\"header\">Header</h1>\n\n<h2 id=\"another-header\">Another header</h2>\n",
+
+		"   Header\n======\n",
+		"<h1 id=\"header\">Header</h1>\n",
+
+		"Header with *inline*\n=====\n",
+		"<h1 id=\"header-with-inline\">Header with <em>inline</em></h1>\n",
+
+		"Paragraph\n\n\n\n\nHeader\n===\n",
+		"<p>Paragraph</p>\n\n<h1 id=\"header\">Header</h1>\n",
+
+		"Trailing space \n====        \n\n",
+		"<h1 id=\"trailing-space\">Trailing space</h1>\n",
+
+		"Trailing spaces\n====        \n\n",
+		"<h1 id=\"trailing-spaces\">Trailing spaces</h1>\n",
+
+		"Double underline\n=====\n=====\n",
+		"<h1 id=\"double-underline\">Double underline</h1>\n\n<p>=====</p>\n",
+	}
+	doTestsBlock(t, tests, EXTENSION_AUTO_HEADER_IDS)
 }
 
 func TestHorizontalRule(t *testing.T) {

M markdown.go → markdown.go

@@ -41,6 +41,7 @@ EXTENSION_FOOTNOTES                              // Pandoc-style footnotes
 	EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK             // No need to insert an empty line to start a (code, quote, order list, unorder list)block
 	EXTENSION_HEADER_IDS                             // specify header IDs  with {#id}
 	EXTENSION_TITLEBLOCK                             // Titleblock ala pandoc
+	EXTENSION_AUTO_HEADER_IDS                        // Create the header ID from the text
 
 	commonHtmlFlags = 0 |
 		HTML_USE_XHTML |