"""CSV parsing and writing. [Copied from PyPy https://bitbucket-assetroot.s3.amazonaws.com/pypy/pypy/1400171824.19/641/_csv.py?Signature=cc%2Bc8m06cBMbsxt2e15XXXUDACk%3D&Expires=1404136251&AWSAccessKeyId=0EMWEFSGA12Z1HF1TZ82 and adapted to Python 3 syntax for Brython] This module provides classes that assist in the reading and writing of Comma Separated Value (CSV) files, and implements the interface described by PEP 305. Although many CSV files are simple to parse, the format is not formally defined by a stable specification and is subtle enough that parsing lines of a CSV file with something like line.split(\",\") is bound to fail. The module supports three basic APIs: reading, writing, and registration of dialects. DIALECT REGISTRATION: Readers and writers support a dialect argument, which is a convenient handle on a group of settings. When the dialect argument is a string, it identifies one of the dialects previously registered with the module. If it is a class or instance, the attributes of the argument are used as the settings for the reader or writer: class excel: delimiter = ',' quotechar = '\"' escapechar = None doublequote = True skipinitialspace = False lineterminator = '\\r\\n' quoting = QUOTE_MINIMAL SETTINGS: * quotechar - specifies a one-character string to use as the quoting character. It defaults to '\"'. * delimiter - specifies a one-character string to use as the field separator. It defaults to ','. * skipinitialspace - specifies how to interpret whitespace which immediately follows a delimiter. It defaults to False, which means that whitespace immediately following a delimiter is part of the following field. * lineterminator - specifies the character sequence which should terminate rows. * quoting - controls when quotes should be generated by the writer. It can take on any of the following module constants: csv.QUOTE_MINIMAL means only when required, for example, when a field contains either the quotechar or the delimiter csv.QUOTE_ALL means that quotes are always placed around fields. csv.QUOTE_NONNUMERIC means that quotes are always placed around fields which do not parse as integers or floating point numbers. csv.QUOTE_NONE means that quotes are never placed around fields. * escapechar - specifies a one-character string used to escape the delimiter when quoting is set to QUOTE_NONE. * doublequote - controls the handling of quotes inside fields. When True, two consecutive quotes are interpreted as one during read, and when writing, each quote character embedded in the data is written as two quotes. """ __version__ = "1.0" QUOTE_MINIMAL, QUOTE_ALL, QUOTE_NONNUMERIC, QUOTE_NONE = range(4) _dialects = {} _field_limit = 128 * 1024 # max parsed field size class Error(Exception): pass class Dialect(object): """CSV dialect The Dialect type records CSV parsing and generation options.""" __slots__ = ["_delimiter", "_doublequote", "_escapechar", "_lineterminator", "_quotechar", "_quoting", "_skipinitialspace", "_strict"] def __new__(cls, dialect, **kwargs): for name in kwargs: if '_' + name not in Dialect.__slots__: raise TypeError("unexpected keyword argument '%s'" % (name,)) if dialect is not None: if isinstance(dialect, str): dialect = get_dialect(dialect) # Can we reuse this instance? if (isinstance(dialect, Dialect) and all(value is None for value in kwargs.values())): return dialect self = object.__new__(cls) def set_char(x): if x is None: return None if isinstance(x, str) and len(x) <= 1: return x raise TypeError("%r must be a 1-character string" % (name,)) def set_str(x): if isinstance(x, str): return x raise TypeError("%r must be a string" % (name,)) def set_quoting(x): if x in range(4): return x raise TypeError("bad 'quoting' value") attributes = {"delimiter": (',', set_char), "doublequote": (True, bool), "escapechar": (None, set_char), "lineterminator": ("\r\n", set_str), "quotechar": ('"', set_char), "quoting": (QUOTE_MINIMAL, set_quoting), "skipinitialspace": (False, bool), "strict": (False, bool), } # Copy attributes notset = object() for name in Dialect.__slots__: name = name[1:] value = notset if name in kwargs: value = kwargs[name] elif dialect is not None: value = getattr(dialect, name, notset) # mapping by name: (default, converter) if value is notset: value = attributes[name][0] if name == 'quoting' and not self.quotechar: value = QUOTE_NONE else: converter = attributes[name][1] if converter: value = converter(value) setattr(self, '_' + name, value) if not self.delimiter: raise TypeError("delimiter must be set") if self.quoting != QUOTE_NONE and not self.quotechar: raise TypeError("quotechar must be set if quoting enabled") if not self.lineterminator: raise TypeError("lineterminator must be set") return self delimiter = property(lambda self: self._delimiter) doublequote = property(lambda self: self._doublequote) escapechar = property(lambda self: self._escapechar) lineterminator = property(lambda self: self._lineterminator) quotechar = property(lambda self: self._quotechar) quoting = property(lambda self: self._quoting) skipinitialspace = property(lambda self: self._skipinitialspace) strict = property(lambda self: self._strict) def _call_dialect(dialect_inst, kwargs): return Dialect(dialect_inst, **kwargs) def register_dialect(name, dialect=None, **kwargs): """Create a mapping from a string name to a dialect class. dialect = csv.register_dialect(name, dialect)""" if not isinstance(name, str): raise TypeError("dialect name must be a string or unicode") dialect = _call_dialect(dialect, kwargs) _dialects[name] = dialect def unregister_dialect(name): """Delete the name/dialect mapping associated with a string name.\n csv.unregister_dialect(name)""" try: del _dialects[name] except KeyError: raise Error("unknown dialect") def get_dialect(name): """Return the dialect instance associated with name. dialect = csv.get_dialect(name)""" try: return _dialects[name] except KeyError: raise Error("unknown dialect") def list_dialects(): """Return a list of all know dialect names names = csv.list_dialects()""" return list(_dialects) class Reader(object): """CSV reader Reader objects are responsible for reading and parsing tabular data in CSV format.""" (START_RECORD, START_FIELD, ESCAPED_CHAR, IN_FIELD, IN_QUOTED_FIELD, ESCAPE_IN_QUOTED_FIELD, QUOTE_IN_QUOTED_FIELD, EAT_CRNL) = range(8) def __init__(self, iterator, dialect=None, **kwargs): self.dialect = _call_dialect(dialect, kwargs) # null characters are not allowed to be in the string so we can use # it as a fall back self._delimiter = self.dialect.delimiter if self.dialect.delimiter else '\0' self._quotechar = self.dialect.quotechar if self.dialect.quotechar else '\0' self._escapechar = self.dialect.escapechar if self.dialect.escapechar else '\0' self._doublequote = self.dialect.doublequote self._quoting = self.dialect.quoting self._skipinitialspace = self.dialect.skipinitialspace self._strict = self.dialect.strict self.input_iter = iter(iterator) self.line_num = 0 self._parse_reset() def _parse_reset(self): self.field = '' self.fields = [] self.state = self.START_RECORD self.numeric_field = False def __iter__(self): return self def __next__(self): self._parse_reset() while True: try: line = next(self.input_iter) except StopIteration: # End of input OR exception if len(self.field) > 0: raise Error("newline inside string") raise self.line_num += 1 if '\0' in line: raise Error("line contains NULL byte") self._parse_process_char(line) self._parse_eol() if self.state == self.START_RECORD: break fields = self.fields self.fields = [] return fields def _parse_process_char(self, line): pos = 0 while pos < len(line): if self.state == self.IN_FIELD: # in unquoted field and have already found one character when starting the field pos2 = pos while pos2 < len(line): if line[pos2] == '\n' or line[pos2] == '\r': # end of line - return [fields] if pos2 > pos: self._parse_add_str(line[pos:pos2]) pos = pos2 self._parse_save_field() self.state = self.EAT_CRNL break elif line[pos2] == self._escapechar[0]: # possible escaped character if pos2 > pos: self._parse_add_str(line[pos:pos2]) pos = pos2 self.state = self.ESCAPED_CHAR break elif line[pos2] == self._delimiter[0]: # save field - wait for new field if pos2 > pos: self._parse_add_str(line[pos:pos2]) pos = pos2 self._parse_save_field() self.state = self.START_FIELD break # normal character - save in field pos2 += 1 else: if pos2 > pos: self._parse_add_str(line[pos:pos2]) pos = pos2 continue elif self.state == self.START_RECORD: if line[pos] == '\n' or line[pos] == '\r': self.state = self.EAT_CRNL else: self.state = self.START_FIELD # restart process continue elif self.state == self.START_FIELD: if line[pos] == '\n' or line[pos] == '\r': # save empty field - return [fields] self._parse_save_field() self.state = self.EAT_CRNL elif (line[pos] == self._quotechar[0] and self._quoting != QUOTE_NONE): # start quoted field self.state = self.IN_QUOTED_FIELD elif line[pos] == self._escapechar[0]: # possible escaped character self.state = self.ESCAPED_CHAR elif self._skipinitialspace and line[pos] == ' ': # ignore space at start of field pass elif line[pos] == self._delimiter[0]: # save empty field self._parse_save_field() else: # begin new unquoted field if self._quoting == QUOTE_NONNUMERIC: self.numeric_field = True self.state = self.IN_FIELD continue elif self.state == self.ESCAPED_CHAR: self._parse_add_char(line[pos]) self.state = self.IN_FIELD elif self.state == self.IN_QUOTED_FIELD: if line[pos] == self._escapechar: # possible escape character self.state = self.ESCAPE_IN_QUOTED_FIELD elif (line[pos] == self._quotechar and self._quoting != QUOTE_NONE): if self._doublequote: # doublequote; " represented by "" self.state = self.QUOTE_IN_QUOTED_FIELD else: #end of quote part of field self.state = self.IN_FIELD else: # normal character - save in field self._parse_add_char(line[pos]) elif self.state == self.ESCAPE_IN_QUOTED_FIELD: self._parse_add_char(line[pos]) self.state = self.IN_QUOTED_FIELD elif self.state == self.QUOTE_IN_QUOTED_FIELD: # doublequote - seen a quote in a quoted field if (line[pos] == self._quotechar and self._quoting != QUOTE_NONE): # save "" as " self._parse_add_char(line[pos]) self.state = self.IN_QUOTED_FIELD elif line[pos] == self._delimiter[0]: # save field - wait for new field self._parse_save_field() self.state = self.START_FIELD elif line[pos] == '\r' or line[pos] == '\n': # end of line - return [fields] self._parse_save_field() self.state = self.EAT_CRNL elif not self._strict: self._parse_add_char(line[pos]) self.state = self.IN_FIELD else: raise Error("'%c' expected after '%c'" % (self._delimiter, self._quotechar)) elif self.state == self.EAT_CRNL: if line[pos] == '\r' or line[pos] == '\n': pass else: raise Error("new-line character seen in unquoted field - " "do you need to open the file " "in universal-newline mode?") else: raise RuntimeError("unknown state: %r" % (self.state,)) pos += 1 def _parse_eol(self): if self.state == self.EAT_CRNL: self.state = self.START_RECORD elif self.state == self.START_RECORD: # empty line - return [] pass elif self.state == self.IN_FIELD: # in unquoted field # end of line - return [fields] self._parse_save_field() self.state = self.START_RECORD elif self.state == self.START_FIELD: # save empty field - return [fields] self._parse_save_field() self.state = self.START_RECORD elif self.state == self.ESCAPED_CHAR: self._parse_add_char('\n') self.state = self.IN_FIELD elif self.state == self.IN_QUOTED_FIELD: pass elif self.state == self.ESCAPE_IN_QUOTED_FIELD: self._parse_add_char('\n') self.state = self.IN_QUOTED_FIELD elif self.state == self.QUOTE_IN_QUOTED_FIELD: # end of line - return [fields] self._parse_save_field() self.state = self.START_RECORD else: raise RuntimeError("unknown state: %r" % (self.state,)) def _parse_save_field(self): field, self.field = self.field, '' if self.numeric_field: self.numeric_field = False field = float(field) self.fields.append(field) def _parse_add_char(self, c): if len(self.field) + 1 > _field_limit: raise Error("field larget than field limit (%d)" % (_field_limit)) self.field += c def _parse_add_str(self, s): if len(self.field) + len(s) > _field_limit: raise Error("field larget than field limit (%d)" % (_field_limit)) self.field += s class Writer(object): """CSV writer Writer objects are responsible for generating tabular data in CSV format from sequence input.""" def __init__(self, file, dialect=None, **kwargs): if not (hasattr(file, 'write') and callable(file.write)): raise TypeError("argument 1 must have a 'write' method") self.writeline = file.write self.dialect = _call_dialect(dialect, kwargs) def _join_reset(self): self.rec = [] self.num_fields = 0 def _join_append(self, field, quoted, quote_empty): dialect = self.dialect # If this is not the first field we need a field separator if self.num_fields > 0: self.rec.append(dialect.delimiter) if dialect.quoting == QUOTE_NONE: need_escape = tuple(dialect.lineterminator) + ( dialect.escapechar, # escapechar always first dialect.delimiter, dialect.quotechar) else: for c in tuple(dialect.lineterminator) + ( dialect.delimiter, dialect.escapechar): if c and c in field: quoted = True need_escape = () if dialect.quotechar in field: if dialect.doublequote: field = field.replace(dialect.quotechar, dialect.quotechar * 2) quoted = True else: need_escape = (dialect.quotechar,) for c in need_escape: if c and c in field: if not dialect.escapechar: raise Error("need to escape, but no escapechar set") field = field.replace(c, dialect.escapechar + c) # If field is empty check if it needs to be quoted if field == '' and quote_empty: if dialect.quoting == QUOTE_NONE: raise Error("single empty field record must be quoted") quoted = 1 if quoted: field = dialect.quotechar + field + dialect.quotechar self.rec.append(field) self.num_fields += 1 def writerow(self, row): dialect = self.dialect try: rowlen = len(row) except TypeError: raise Error("sequence expected") # join all fields in internal buffer self._join_reset() for field in row: quoted = False if dialect.quoting == QUOTE_NONNUMERIC: try: float(field) except: quoted = True # This changed since 2.5: # quoted = not isinstance(field, (int, long, float)) elif dialect.quoting == QUOTE_ALL: quoted = True if field is None: self._join_append("", quoted, rowlen == 1) else: self._join_append(str(field), quoted, rowlen == 1) # add line terminator self.rec.append(dialect.lineterminator) self.writeline(''.join(self.rec)) def writerows(self, rows): for row in rows: self.writerow(row) def reader(*args, **kwargs): """ csv_reader = reader(iterable [, dialect='excel'] [optional keyword args]) for row in csv_reader: process(row) The "iterable" argument can be any object that returns a line of input for each iteration, such as a file object or a list. The optional \"dialect\" parameter is discussed below. The function also accepts optional keyword arguments which override settings provided by the dialect. The returned object is an iterator. Each iteration returns a row of the CSV file (which can span multiple input lines)""" return Reader(*args, **kwargs) def writer(*args, **kwargs): """ csv_writer = csv.writer(fileobj [, dialect='excel'] [optional keyword args]) for row in sequence: csv_writer.writerow(row) [or] csv_writer = csv.writer(fileobj [, dialect='excel'] [optional keyword args]) csv_writer.writerows(rows) The \"fileobj\" argument can be any object that supports the file API.""" return Writer(*args, **kwargs) undefined = object() def field_size_limit(limit=undefined): """Sets an upper limit on parsed fields. csv.field_size_limit([limit]) Returns old limit. If limit is not given, no new limit is set and the old limit is returned""" global _field_limit old_limit = _field_limit if limit is not undefined: if not isinstance(limit, (int, long)): raise TypeError("int expected, got %s" % (limit.__class__.__name__,)) _field_limit = limit return old_limit