From c012b0a5338059d884eaf65f6d80c4f31143cf0a Mon Sep 17 00:00:00 2001
From: Niklas Fasching <niklas.fasching@gmail.com>
Date: Sun, 16 Dec 2018 23:21:26 +0100
Subject: [PATCH] Add support for ": example" elements

---
 org/document.go          |  3 +++
 org/example.go           | 26 ++++++++++++++++++++++++++
 org/html.go              | 13 +++++++++++++
 org/org.go               | 10 ++++++++++
 org/testdata/blocks.html |  8 ++++++++
 org/testdata/blocks.org  |  6 ++++++
 org/testdata/lists.html  |  6 ++++++
 org/testdata/lists.org   |  3 +++
 8 files changed, 75 insertions(+)
 create mode 100644 org/example.go

diff --git a/org/document.go b/org/document.go
index 6a62d79..ffe56de 100644
--- a/org/document.go
+++ b/org/document.go
@@ -49,6 +49,7 @@ var lexFns = []lexFn{
 	lexHorizontalRule,
 	lexKeywordOrComment,
 	lexFootnoteDefinition,
+	lexExample,
 	lexText,
 }
 
@@ -169,6 +170,8 @@ func (d *Document) parseOne(i int, stop stopFn) (consumed int, node Node) {
 		consumed, node = d.parseBlock(i, stop)
 	case "text":
 		consumed, node = d.parseParagraph(i, stop)
+	case "example":
+		consumed, node = d.parseExample(i, stop)
 	case "horizontalRule":
 		consumed, node = d.parseHorizontalRule(i, stop)
 	case "comment":
diff --git a/org/example.go b/org/example.go
new file mode 100644
index 0000000..9d716f3
--- /dev/null
+++ b/org/example.go
@@ -0,0 +1,26 @@
+package org
+
+import (
+	"regexp"
+)
+
+type Example struct {
+	Children []Node
+}
+
+var exampleLineRegexp = regexp.MustCompile(`^(\s*): (.*)`)
+
+func lexExample(line string) (token, bool) {
+	if m := exampleLineRegexp.FindStringSubmatch(line); m != nil {
+		return token{"example", len(m[1]), m[2], m}, true
+	}
+	return nilToken, false
+}
+
+func (d *Document) parseExample(i int, parentStop stopFn) (int, Node) {
+	example, start := Example{}, i
+	for ; !parentStop(d, i) && d.tokens[i].kind == "example"; i++ {
+		example.Children = append(example.Children, Text{d.tokens[i].content})
+	}
+	return i - start, example
+}
diff --git a/org/html.go b/org/html.go
index 6f60db0..5b88d20 100644
--- a/org/html.go
+++ b/org/html.go
@@ -88,6 +88,8 @@ func (w *HTMLWriter) writeNodes(ns ...Node) {
 
 		case Paragraph:
 			w.writeParagraph(n)
+		case Example:
+			w.writeExample(n)
 		case HorizontalRule:
 			w.writeHorizontalRule(n)
 		case Text:
@@ -264,6 +266,17 @@ func (w *HTMLWriter) writeParagraph(p Paragraph) {
 	w.WriteString("\n</p>\n")
 }
 
+func (w *HTMLWriter) writeExample(e Example) {
+	w.WriteString(`<pre class="example">` + "\n")
+	if len(e.Children) != 0 {
+		for _, n := range e.Children {
+			w.writeNodes(n)
+			w.WriteString("\n")
+		}
+	}
+	w.WriteString("\n</pre>\n")
+}
+
 func (w *HTMLWriter) writeHorizontalRule(h HorizontalRule) {
 	w.WriteString("<hr>\n")
 }
diff --git a/org/org.go b/org/org.go
index df99a93..ab8306f 100644
--- a/org/org.go
+++ b/org/org.go
@@ -76,6 +76,8 @@ func (w *OrgWriter) writeNodes(ns ...Node) {
 
 		case Paragraph:
 			w.writeParagraph(n)
+		case Example:
+			w.writeExample(n)
 		case HorizontalRule:
 			w.writeHorizontalRule(n)
 		case Text:
@@ -171,6 +173,14 @@ func (w *OrgWriter) writeParagraph(p Paragraph) {
 	w.WriteString("\n")
 }
 
+func (w *OrgWriter) writeExample(e Example) {
+	for _, n := range e.Children {
+		w.WriteString(w.indent + ":" + " ")
+		w.writeNodes(n)
+		w.WriteString("\n")
+	}
+}
+
 func (w *OrgWriter) writeKeyword(k Keyword) {
 	w.WriteString(w.indent + fmt.Sprintf("#+%s: %s\n", k.Key, k.Value))
 }
diff --git a/org/testdata/blocks.html b/org/testdata/blocks.html
index b90c498..5160801 100644
--- a/org/testdata/blocks.html
+++ b/org/testdata/blocks.html
@@ -27,6 +27,14 @@ multiple lines including
 empty lines!
 
 it also has multiple parameters
+
+note that /inline/ *markup* ignored
+</pre>
+<pre class="example">
+examples like this
+are also supported
+note that /inline/ *markup* ignored
+
 </pre>
 <blockquote>
 <p>
diff --git a/org/testdata/blocks.org b/org/testdata/blocks.org
index bbb4390..1ed1c7e 100644
--- a/org/testdata/blocks.org
+++ b/org/testdata/blocks.org
@@ -21,8 +21,14 @@ multiple lines including
 empty lines!
 
 it also has multiple parameters
+
+note that /inline/ *markup* ignored
 #+END_EXAMPLE
 
+: examples like this
+: are also supported
+: note that /inline/ *markup* ignored
+
 #+BEGIN_QUOTE
 Mongodb is *webscale*. (source: [[http://www.mongodb-is-web-scale.com/][mongodb-is-web-scale]])
 
diff --git a/org/testdata/lists.html b/org/testdata/lists.html
index bae58c4..fdc0d24 100644
--- a/org/testdata/lists.html
+++ b/org/testdata/lists.html
@@ -84,5 +84,11 @@ and text with an empty line in between as well!
 <p>
 unordered list item 4
 </p>
+<pre class="example">
+with an example
+
+that spans multiple lines
+
+</pre>
 </li>
 </ul>
diff --git a/org/testdata/lists.org b/org/testdata/lists.org
index 54211db..8c16479 100644
--- a/org/testdata/lists.org
+++ b/org/testdata/lists.org
@@ -18,3 +18,6 @@
 
      and text with an empty line in between as well!
 - unordered list item 4
+  : with an example
+  : 
+  : that spans multiple lines