A very simple RIS file parser

ris.py

""" Process RIS format following the standard at",
http://referencemanager.com/sites/rm/files/m/direct_export_ris.pdf """
import re

ALLOWED_TAGS = {"TY" : "Record start",
                "ER" : "Record end",
                "A2" : "Secondary author", 
                "A3" : "Tertiary Author",
                "A4" : "Subsidiary Author",
                "AB" : "Abstract", 
                "AD" : "Author Address",
                "AN" : "Accession Number",
                "AU" : "Author",
                "C1" : "Custom 1",
                "C2" : "Custom 2",
                "C3" : "Custom 3",
                "C4" : "Custom 4",
                "C5" : "Custom 5",
                "C6" : "Custom 6",
                "C7" : "Custom 7",
                "C8" : "Custom 8",
                "CA" : "Caption",
                "CN" : "Call Number",
                "CY" : "Place Published",
                "DA" : "Date",
                "DB" : "Name of Database",
                "DO" : "DOI",
                "DP" : "Database Provider",
                "ET" : "Edition",
                "J2" : "Alternate Title",
                "KW" : "Keywords",
                "L1" : "File Attachments",
                "L4" : "Figure",
                "LA" : "Language",
                "LB" : "Label",
                "IS" : "Number",
                "M3" : "Type of Work",
                "N1" : "Notes",
                "NV" : "Number of Volumes",
                "OP" : "Original Publication",
                "PB" : "Publisher",
                "PY" : "Year"}
REFERENCE_TYPES = {"ABST" : "Abstract", 
                   "ADVS" : "Audiovisual material", 
                   "ART" : "Art Work",
                   "BILL" : "Bill/Resolution",
                   "BOOK" : "Book, Whole",
                   "CASE" : "Case",
                   "CHAP" : "Book chapter",
                   "COMP" : "Computer program",
                   "CONF" : "Conference proceeding",
                   "CTLG" : "Catalog",
                   "DATA" : "Data file",
                   "ELEC" : "Electronic Citation",
                   "GEN" : "Generic", 
                   "HEAR" : "Hearing", 
                   "ICOMM" : "Internet Communication", 
                   "INPR" : "In Press", 
                   "JFULL" : "Journal (full)", 
                   "JOUR" : "Journal", 
                   "MAP" : "Map", 
                   "MGZN" : "Magazine article", 
                   "MPCT" : "Motion picture", 
                   "MUSIC" : "Music score", 
                   "NEWS" : "Newspaper", 
                   "PAMP" : "Pamphlet", 
                   "PAT" : "Patent", 
                   "PCOMM" : "Personal communication", 
                   "RPRT" : "Report", 
                   "SER" : "Serial (Book, Monograph)", 
                   "SLIDE" : "Slide", 
                   "SOUND" : "Sound recording", 
                   "STAT" : "Statute", 
                   "THES" : "Thesis/Dissertation", 
                   "UNBILl" : "Unenacted bill/resolution", 
                   "UNPB" : "Unpublished work", 
                   "VIDEO" : "Video recording"}
class RIS:
    """ RIS file structure """
    def __init__(self, in_file=None):
        """ Initialize and parse input """
        self.records = []
        if in_file:
            self.parse(in_file)
    def parse(self, in_file):
        """ Parse input file """
        self.current_tag = None
        self.current_record = None
        prog = re.compile("^([A-Z][A-Z0-9]) *- *(.*)")
        lines = []
        # Eliminate blank lines
        for line in in_file:
            line = line.strip()
            if len(line) > 0:
                lines.append(line)
        for line in lines:
            match = prog.match(line)
            if match:
                tag = match.groups()[0]
                field = match.groups()[1]
                self.process_field(tag, field)
            else:
                raise ValueError(line)
    def process_field(self, tag, field):
        """ Process RIS file field """
        if tag == "TY":
            self.current_record = {tag: field}
        elif tag == "ER":
            self.records.append(self.current_record)
            self.current_record = None
        elif tag in ["AU", "AD", "KW", "N1"]:
            if tag in self.current_record:
                self.current_record[tag].append(field)
            else:
                self.current_record[tag] = [field]
        else:
            if not tag in self.current_record:
                self.current_record[tag] = field
            else:
                error_str = "Duplicate tag: %s" % tag
                raise ValueError(error_str)

def main():
    """ Test the code """
    import pprint
    with open("collaborations.ris", "rt") as ris_file:
        ris = RIS(ris_file)
        pp = pprint.PrettyPrinter()
        pp.pprint(ris.records)

if __name__ == "__main__":
    main()