italicparser: Add first version

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

include/maddy/italicparser.h

@@ -0,0 +1,50 @@
+/*
+ * This project is licensed under the MIT license. For more information see the
+ * LICENSE file.
+ */
+#pragma once
+
+// -----------------------------------------------------------------------------
+
+#include <string>
+#include <regex>
+
+#include "maddy/lineparser.h"
+
+// -----------------------------------------------------------------------------
+
+namespace maddy {
+
+// -----------------------------------------------------------------------------
+
+/**
+ * ItalicParser
+ *
+ * @class
+ */
+class ItalicParser : public LineParser
+{
+public:
+  /**
+   * Parse
+   *
+   * From Markdown: `text *text*`
+   *
+   * To HTML: `text <i>text</i>`
+   *
+   * @method
+   * @param {std::string&} line The line to interpret
+   * @return {void}
+   */
+  void
+  Parse(std::string& line) override
+  {
+    std::regex re("(?!.*`.*|.*<code>.*)\\*(?!.*`.*|.*<\\/code>.*)([^\\*]*)\\*(?!.*`.*|.*<\\/code>.*)");
+    static std::string replacement = "<i>$1</i>";
+    line = std::regex_replace(line, re, replacement);
+  }
+}; // class ItalicParser
+
+// -----------------------------------------------------------------------------
+
+} // namespace maddy