We store the lines we’re working on as objects of class Line. These contain the text of the line, along with a flag indicating the line type, and an indentation level.
INFINITY = 9999
LINE_TYPES = [ :BLANK, :HEADING, :LIST, :PARAGRAPH, :RULE, :VERBATIM, ]
The indentation nesting level
A prefix or parameter. For LIST lines, this is the text that introduced the list item (the label)
A flag. For list lines, this is the type of the list
the number of leading spaces
true if this line has been deleted from the list of lines