Simple demonstration of using pyparsing's indentedBlock recursively
pyparsing, python
Solution
This is a bit old, but here's a partial answer:
from pyparsing import *
COMMENT = pythonStyleComment
OPCOMMENT = Optional(COMMENT)
IDENT = Word(alphas, alphanums + '_')
attribute = IDENT + Suppress(':') + Word(alphanums) + OPCOMMENT
element = Suppress('-') + IDENT + OPCOMMENT
elementBlock = Forward()
blockContent = attribute|elementBlock|COMMENT
elementBlock << element + Optional(indentedBlock(blockContent, [1]))
I've assumed that elements can contain both attributes and elements in arbitrary order. `elementBlock` will parse the whole tree.
It showcases the use of `indentedBlock` so, to make it short, it doesn't allow for comments outside the tree, and it will accept only one root element (not a problem for XML...)
About `indentStack`: it keeps a list of the current number of indented levels and the last element of the list shows the current indent column. As the documentation points out, all the statements on a grammar with nested blocks using indentation should share the same list. As there's only one, I've just created it straight in the call to `indentedBlock`.
I leave turning the result into XML as an exercise for the reader :-P
Problem
I am trying to use `indentedBlock` in pyparsing (which looks awesome to me) to dissect some nested indentations, but am struggling a bit with comprehending its description in the API reference (or the more specific examples under http://pyparsing.wikispaces.com or the mentioning in How do I parse indents and dedents with pyparsing?). Could someone please point me to a concise demonstration or explanation of how to use `indentedBlock` recursively, or maybe provide one here? E.g., how would we convert something YAMLish like... ``` - a1_el - b1_el x1_attr: 1 x2_attr: 2 - b2_el - c1_el # I am a comment - b3_el x1_attr: 1 ``` ...into some XML representation such as ... ``` <a1_el> <b1_el x1_attr="1" x2_attr="2"/> <b2_el> <c1_el/><!-- I am a comment --> </b2_el> <b3_el x1_attr="1"/> </a1_el> ``` ...with `indentedBlock`? (Also: In what practical situations would I need the different otpions for the `indentStack` parameter?). Thanks a lot!