Libraries: Add LibMarkdown

Libraries/LibMarkdown/MDList.cpp

@@ -0,0 +1,89 @@
+#include <AK/StringBuilder.h>
+#include <LibMarkdown/MDList.h>
+
+String MDList::render_to_html() const
+{
+    StringBuilder builder;
+
+    const char* tag = m_is_ordered ? "ol" : "ul";
+    builder.appendf("<%s>", tag);
+
+    for (auto& item : m_items) {
+        builder.append("<li>");
+        builder.append(item.render_to_html());
+        builder.append("</li>\n");
+    }
+
+    builder.appendf("</%s>\n", tag);
+
+    return builder.build();
+}
+
+String MDList::render_for_terminal() const
+{
+    StringBuilder builder;
+
+    int i = 0;
+    for (auto& item : m_items) {
+        builder.append("  ");
+        if (m_is_ordered)
+            builder.appendf("%d. ", ++i);
+        else
+            builder.append("* ");
+        builder.append(item.render_for_terminal());
+        builder.append("\n");
+    }
+    builder.append("\n");
+
+    return builder.build();
+}
+
+bool MDList::parse(Vector<StringView>::ConstIterator& lines)
+{
+    bool first = true;
+    while (true) {
+        if (lines.is_end())
+            break;
+        const StringView& line = *lines;
+        if (line.is_empty())
+            break;
+
+        bool appears_unordered = false;
+        int offset = 0;
+        if (line.length() > 2)
+            if (line[1] == ' ' && (line[0] == '*' || line[0] == '-')) {
+                appears_unordered = true;
+                offset = 2;
+            }
+
+        bool appears_ordered = false;
+        for (int i = 0; i < 10 && i < line.length(); i++) {
+            char ch = line[i];
+            if ('0' <= ch && ch <= '9')
+                continue;
+            if (ch == '.' || ch == ')')
+                if (i + 1 < line.length() && line[i + 1] == ' ') {
+                    appears_ordered = true;
+                    offset = i + 1;
+                }
+            break;
+        }
+
+        ASSERT(!(appears_unordered && appears_ordered));
+        if (!appears_unordered && !appears_ordered)
+            return false;
+        if (first)
+            m_is_ordered = appears_ordered;
+        else if (m_is_ordered != appears_ordered)
+            return false;
+
+        first = false;
+        MDText text;
+        bool success = text.parse(line.substring_view(offset, line.length() - offset));
+        ASSERT(success);
+        m_items.append(move(text));
+        ++lines;
+    }
+
+    return !first;
+}