CSV example.

examples/csv.py

+##############################################################################
+# 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 arpeggio import *
+from arpeggio.export import PMDOTExport, PTDOTExport
+from arpeggio import RegExMatch as _
+
+def newline():                  return _(r'\n+')
+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(ZeroOrMore(newline), record, OneOrMore(newline)), EndOfFile
+
+
+if __name__ == "__main__":
+
+    test_data = '''
+Unquoted test, "Quoted test", 23234, One Two Three, "343456.45"
+
+Unquoted test 2, "Quoted test 2", 23234, One Two Three, "343456.45"
+Unquoted test 3, "Quoted test 3", 23234, One Two Three, "343456.45"
+    '''
+
+    try:
+        # First we will make a parser - an instance of the calc 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 ', reduce_tree=True, debug=True)
+
+        # Then we export it to a dot file in order to visualise it. This is
+        # particularly handy for debugging purposes.
+        # We can make a jpg out of it using dot (part of graphviz) like this:
+        # dot -O -Tpng calc_parse_tree_model.dot
+        PMDOTExport().exportFile(parser.parser_model,
+                                 "csv_parse_tree_model.dot")
+
+        # Creating parse tree out of textual input
+        parse_tree = parser.parse(test_data)
+
+        # Then we export it to a dot file in order to visualise it.
+        # dot -O -Tpng calc_parse_tree.dot
+        PTDOTExport().exportFile(parse_tree,
+                                 "csv_parse_tree.dot")
+
+    except NoMatch, e:
+        print "Expected %s at position %s." % (e.value, str(e.parser.pos_to_linecol(e.position)))