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##############################################################################
# Name: csv.py
# Purpose: Implementation of CSV parser in arpeggio.
# Author: Igor R. Dejanovic <igor DOT dejanovic AT gmail DOT com>
# Copyright: (c) 2014 Igor R. Dejanovic <igor DOT dejanovic AT gmail DOT com>
# License: MIT License
##############################################################################
from __future__ import unicode_literals
import pprint
import os
from arpeggio import *
from arpeggio import RegExMatch as _
def record(): return field, ZeroOrMore(",", field)
def field(): return [quoted_field, field_content]
def quoted_field(): return '"', field_content_quoted, '"'
def field_content(): return _(r'([^,\n])+')
def field_content_quoted(): return _(r'(("")|([^"]))+')
def csvfile(): return OneOrMore([record, '\n']), EOF
class CSVVisitor(PTNodeVisitor):
def visit_field(self, node, children):
value = children[0]
try:
return float(value)
except:
pass
try:
return int(value)
except:
return value
def visit_record(self, node, children):
# record is a list of fields. The children nodes are fields so just
# transform it to list.
return list(children)
def visit_csvfile(self, node, children):
# We are not interested in newlines so we will filter them.
return [x for x in children if x!='\n']
def main(debug=False):
# First we will make a parser - an instance of the CVS parser model.
# Parser model is given in the form of python constructs therefore we
# are using ParserPython class.
# Skipping of whitespace will be done only for tabs and spaces. Newlines
# have semantics in csv files. They are used to separate records.
parser = ParserPython(csvfile, ws='\t ', debug=debug)
# Creating parse tree out of textual input
current_dir = os.path.dirname(__file__)
test_data = open(os.path.join(current_dir, 'test_data.csv'), 'r').read()
parse_tree = parser.parse(test_data)
# Create list of lists using visitor
csv_content = visit_parse_tree(parse_tree, CSVVisitor())
print("This is a list of lists with the data from CSV file.")
pp = pprint.PrettyPrinter(indent=4)
pp.pprint(csv_content)
if __name__ == "__main__":
# In debug mode dot (graphviz) files for parser model
# and parse tree will be created for visualization.
# Checkout current folder for .dot files.
main(debug=True)
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