Convert a txt file to html file

$ python txt2html.py < input.txt > output.html

1. Support *emphasis*

   Rule: r'\*(.+?)\*'

2. Support url

   Rule: r'(http://[\.a-zA-Z/]+)'

3. Support email

   Rule: r'[\.a-zA-Z]+@[\.a-zA-Z]+[a-zA-Z]+'

1. Support title

   Rule: First heading

2. Support heading

   Rule: A block with no \n with less than 70 characters and the last charater is not :

3. Support list

   Rule: A consecutive array of list items

4. Support list items

   Rule: A block starting with -(hyphen)

5. Support paragraph

   Rule: A block that is not marked down as a heading/title or list/list items

Token: block, lines

util: to break things into block and lines (lexemes)

Syntax Rules: rules (conditions) and filters (regex)

rules: syntax rules for block-level token, e.g.: list, list item, title, heading, paragraph, etc.

filters: syntax rules for within-block elements, e.g.: email, url, emphasis, etc.

Semantics: How to interpret each rule on a block

handlers: handle rule action and filter, using visitor pattern

parser: Assemble rules and filters

1. Debug framework
2. Refactor filter to a standalone class
3. Populate more rules and filters
4. Potential Extension: Markdown for table and table item
5. Potential Extension: Support more markup language (Markdown, XML, YAML, etc)