Re: [Pyparsing] A newbie w/nested structures

[Paul M. <pa...@al...>]

Tim -

First of all, this is a very ambitious parser to start with, so don't be
discouraged.  It is a recursive grammar, which is also a more advanced
parser to start with.

Here are some suggestions on getting started:
- pick a part of the sample ADL (I would suggest working section by section)
- develop a simple BNF for this grammar

Here is a sample parser for the ontology section.  It is a recursive
example, defining a valueDef that is defined in terms of component
valueDefs.  It also shows the comment format, and the mechanism for skipping
comments.  I hope this sample gives you a jump start on a more complete ADL
parser.

-- Paul


from pyparsing import *

LT,GT,EQ,LPAR,RPAR,LBRK,RBRK,BAR,QUOT,SEMI = map(Suppress,"<>=()[]|';")
upper = srange("[A-Z]")
lower = upper.lower()
attrName = Word(lower,alphanums+"_")

key = attrName | (LBRK+quotedString+RBRK)
quotedString.setParseAction(removeQuotes)

valueDef = Forward()
valueDef << ( key + EQ + LT + ZeroOrMore( Group(valueDef | quotedString )) +
GT )
ontologySection = "ontology" + valueDef

comment = "--" + restOfLine
ontologySection.ignore(comment)

sample = """
ontology
	term_definitions = <
		["en"] = <
			items = <
				["at0000"] = <
					description = <"Generic reporting
composition in response to a request for information or testing">
					text = <"Report">
				>
				["at0001"] = <
					description = <"@ internal @">
					text = <"Tree">
				>
				["at0002"] = <
					description = <"Information about
the request">
					text = <"Request details">
				>
				["at0003"] = <
					description = <"Identification of
the request">
					text = <"Request identifier">
				>
				["at0004"] = <
					description = <"Information about
the requesting clinician">
					text = <"Requesting clinician">
				>
				["at0005"] = <
					description = <"The date of the
request">
					text = <"Date of request">
				>
				["at0006"] = <
					description = <"Details of the
report">
					text = <"Report details">
				>
				["at0007"] = <
					description = <"Identification
information about the report">
					text = <"Report identifier">
				>
				["at0008"] = <
					description = <"Collection of
parties who have been copied the report">
					text = <"Copies to">
				>
				["at0009"] = <
					description = <"Details of the
parties to whom the copies have been copied">
					text = <"Copied party details">
				>
				["at0010"] = <
					description = <"Collection of
parties who have been referred to generate the report">
					text = <"Referrals">
				>
				["at0011"] = <
					description = <"Details of the
parties to whom the specimen or findings have been referred for special
testing or elaboration">
					text = <"Referred party details">
				>
				["at0012"] = <
					description = <"Details for
contacting requesting clinician">
					text = <"Contact details of
requesting clinician">
				>
				["at0013"] = <
					description = <"The date and time
the report was officially issued">
					text = <"Date/time report issued">
				>
				["at0014"] = <
					description = <"The status of the
report">
					text = <"Status">
				>
				["at0015"] = <
					description = <"This report is the
final report">
					text = <"Final">
				>
				["at0016"] = <
					description = <"This report is an
interim report and a final or further interim report is to be expected">
					text = <"Interim">
				>
				["at0017"] = <
					description = <"This report is
supplementary to a previous report">
					text = <"Supplementary">
				>
				["at0018"] = <
					description = <"This report is a
correction or amendment of a previous report">
					text = <"Corrected/amended">
				>
			>
		>
	>
"""

res = ontologySection.parseString(sample)
from pprint import pprint
pprint( res.asList() )