md_tw.py: Add Text Wrap classes (derived from mistune' classes).

* md_tw.py (TWBlockLexer, TWInlineLexer, TWRenderer)
(TWMarkdown): New classes.
* tests/data/paragraphs-with-inline-wrapped.md: New file.
* tests/data/paragraphs-with-inline.md: New file.
* tests/data/paragraphs-wrapped.md: New file.
* tests/data/paragraphs.md: New file.
* tests/test_md_tw.py (TestTWBlockLexer, TestTWInlineLexer,
  TestTWRenderer, TestTWMarkdown)
  (TestTextWrapParagraphs): New test classes.

1 files changed, 91 insertions, 0 deletions

diff --git a/md_tw.py b/md_tw.py
index 312e249..9ebe609 100644
--- a/md_tw.py
+++ b/md_tw.py
@@ -18,5 +18,96 @@
 #   along with markdown-textwrap (see COPYING).  If not, see
 #   <http://www.gnu.org/licenses/>.
 
+import textwrap
+
+from mistune import BlockLexer, InlineLexer, Renderer, Markdown
+
+
+class TWBlockLexer(BlockLexer):
+    """Text Wrap Block level lexer for block grammars."""
+
+    def __init__(self, rules=None, **kwargs):
+        super(TWBlockLexer, self).__init__(rules, **kwargs)
+
+        self.default_rules = ['paragraph', 'text']
+
+
+class TWInlineLexer(InlineLexer):
+    """Text Wrap Inline level lexer for inline gramars."""
+
+    def __init__(self, renderer, rules=None, **kwargs):
+        super(TWInlineLexer, self).__init__(renderer, rules, **kwargs)
+
+        # No inline rules.
+        self.default_rules = []
+
+    def output(self, text, rules=None):
+        # Don't parse inline text.
+        return text
+
+
+class TWRenderer(Renderer):
+    """Text Wrap Renderer."""
+
+    def __init__(self, **kwargs):
+        super(TWRenderer, self).__init__(**kwargs)
+
+        # Initalize textwrap.TextWrapper class
+        self.tw = textwrap.TextWrapper(
+            width=kwargs.get('tw_width', 72)
+        )
+
+
+    def _tw_set_options(self, **kwargs):
+        """
+        Set options for the local textwrap.TextWrapper instance.
+        """
+        # Recognized options.
+        opts = [
+            'width',
+            'initial_indent',
+            'subsequent_indent',
+            'drop_whitespace'
+        ]
+
+        for opt, val in kwargs.items():
+            if not opt in opts:
+                continue
+
+            # Set option
+            setattr(self.tw, opt, val)
+
+
+    def _tw_fill(self, text, **kwargs):
+        """Wrap text.
+        """
+        self._tw_set_options(**kwargs)
+        return self.tw.fill(text)
+
+
+    def paragraph(self, text):
+        return '\n{}\n'.format(self._tw_fill(text))
+
+
+class TWMarkdown(Markdown):
+    """Text Wrap Markdown parser.
+    """
+
+    def __init__(self, **kwargs):
+        renderer = TWRenderer(**kwargs)
+
+        super(TWMarkdown, self).__init__(
+            renderer,
+            TWInlineLexer,
+            TWBlockLexer
+        )
+
+    def parse(self, text):
+        out = super(TWMarkdown, self).parse(text)
+
+        # Strip newline at the beginning.
+        return out.lstrip('\n')
+
+
 def main():
     print('USAGE: md_tw 72 file.md file2.md [...]')