Simple Markdown parser.

Parse just a tiny subset of Markdown, to basically collapse
multiple whitespace and do paragraphs only after two newlines.
Also one-level, unordered lists are supported. The output can
be eg. directly forwarded to canvas::Text.

simgear/misc/CMakeLists.txt

@@ -5,6 +5,7 @@ set(HEADERS
     CSSBorder.hxx
     ListDiff.hxx
     ResourceManager.hxx
+    SimpleMarkdown.hxx
     SVGpreserveAspectRatio.hxx
     interpolator.hxx
     make_new.hxx
@@ -23,6 +24,7 @@ set(HEADERS
 set(SOURCES
     CSSBorder.cxx
     ResourceManager.cxx
+    SimpleMarkdown.cxx
     SVGpreserveAspectRatio.cxx
     interpolator.cxx
     sg_dir.cxx
@@ -65,6 +67,11 @@ target_link_libraries(test_path ${TEST_LIBS})
 
 endif(ENABLE_TESTS)
 
+add_boost_test(SimpleMarkdown
+  SOURCES SimpleMarkdown_test.cxx
+  LIBRARIES ${TEST_LIBS}
+)
+
 add_boost_test(SVGpreserveAspectRatio
   SOURCES SVGpreserveAspectRatio_test.cxx
   LIBRARIES ${TEST_LIBS}

simgear/misc/SimpleMarkdown.cxx

@@ -0,0 +1,104 @@
+// Really simple markdown parser
+//
+// Copyright (C) 2014  Thomas Geymayer <tomgey@gmail.com>
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU Library General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
+
+#include "SimpleMarkdown.hxx"
+
+namespace simgear
+{
+
+  // White space
+  static bool isSpace(const char c)
+  {
+    return c == ' ' || c == '\t';
+  }
+  
+  // Unordered list item
+  static bool isULItem(const char c)
+  {
+    return c == '*' || c == '+' || c == '-';
+  }
+
+  //----------------------------------------------------------------------------
+  std::string SimpleMarkdown::parse(const std::string& src)
+  {
+    std::string out;
+
+    int num_space = 0,
+        num_newline = 0;
+    bool line_empty = true;
+
+    for( std::string::const_iterator it = src.begin();
+                                     it != src.end();
+                                   ++it )
+    {
+      if( isSpace(*it) )
+      {
+        ++num_space;
+      }
+      else if( *it == '\n' )
+      {
+        // Two or more whitespace at end of line -> line break
+        if( !line_empty && num_space >= 2 )
+        {
+          out.push_back('\n');
+          line_empty = true;
+        }
+
+        ++num_newline;
+        num_space = 0;
+      }
+      else
+      {
+        // Remove all new lines before first printable character
+        if( out.empty() )
+          num_newline = 0;
+
+        // Two or more new lines (aka. at least one empty line) -> new paragraph
+        if( num_newline >= 2 )
+        {
+          out.append("\n\n");
+
+          line_empty = true;
+          num_newline = 0;
+        }
+
+        // Replace unordered list item markup at begin of line with bullet
+        // (TODO multilevel lists, indent multiple lines, etc.)
+        if( (line_empty || num_newline) && isULItem(*it) )
+        {
+          if( num_newline < 2 )
+            out.push_back('\n');
+          out.append("\xE2\x80\xA2");
+        }
+        else
+        {
+          // Collapse multiple whitespace
+          if( !line_empty && (num_space || num_newline) )
+            out.push_back(' ');
+          out.push_back(*it);
+        }
+
+        line_empty = false;
+        num_space = 0;
+        num_newline = 0;
+      }
+    }
+    return out;
+  }
+
+} // namespace simgear

simgear/misc/SimpleMarkdown.hxx

@@ -0,0 +1,39 @@
+///@file Really simple markdown parser
+//
+// Copyright (C) 2014  Thomas Geymayer <tomgey@gmail.com>
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU Library General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
+
+#ifndef SIMPLE_MARKDOWN_HXX_
+#define SIMPLE_MARKDOWN_HXX_
+
+#include <string>
+
+namespace simgear
+{
+  /**
+   * Really simple mardown parser. Currently just paragraphs, new lines and
+   * one level of unordered lists are supported.
+   *
+   * @see http://en.wikipedia.org/wiki/Markdown
+   */
+  class SimpleMarkdown
+  {
+    public:
+      static std::string parse(const std::string& src);
+  };
+} // namespace simgear
+
+#endif /* SIMPLE_MARKDOWN_HXX_ */

simgear/misc/SimpleMarkdown_test.cxx

@@ -0,0 +1,34 @@
+/// Unit tests for simple markdown parser
+#define BOOST_TEST_MODULE misc
+#include <BoostTestTargetConfig.h>
+
+#include "SimpleMarkdown.hxx"
+
+BOOST_AUTO_TEST_CASE( basic_markdown )
+{
+  std::string const src(
+    "  \n"
+    "\n"
+    "blub\n"
+    "* \tlist item\n"
+    "*  another\t item\n"
+    "\n"
+    "test blubt\n"
+    " aha  \n"
+    "asd\n"
+    "  * 2nd list, another   item\n"
+    "  * 2nd list, one more..."
+  );
+  std::string const out(
+    "blub\n"
+    "\xE2\x80\xA2 list item\n"
+    "\xE2\x80\xA2 another item\n"
+    "\n"
+    "test blubt aha\n"
+    "asd\n"
+    "\xE2\x80\xA2 2nd list, another item\n"
+    "\xE2\x80\xA2 2nd list, one more..."
+  );
+
+  BOOST_CHECK_EQUAL(simgear::SimpleMarkdown::parse(src), out);
+}