def extract(cls, value: str) -> SymbologyIdentifier:
"""Extract the Symbology Identifier from the given value.
Args:
value: The string to extract a Symbology Identifier from.
Returns:
Metadata about the extracted Symbology Identifier.
Raises:
ParseError: If the parsing fails.o
"""
if not value.startswith("]"):
raise ParseError(
f"Failed to get Symbology Identifier from {value!r}. "
"No initial ']' flag character found."
)
try:
symbology = Symbology(value[1])
except ValueError:
raise ParseError(
f"Failed to get Symbology Identifier from {value!r}. "
f"{value[1]!r} is not a recognized code character."
)
if symbology == Symbology.SYSTEM_EXPANSION:
modifiers_length = int(value[2]) + 1
else:
modifiers_length = 1
modifiers = value[2 : 2 + modifiers_length]
value = f"]{symbology.value}{modifiers}"
gs1_symbology: Optional[GS1Symbology]
try:
gs1_symbology = GS1Symbology(f"{symbology.value}{modifiers}")
except ValueError:
gs1_symbology = None
return cls(
value=value,
symbology=symbology,
modifiers=modifiers,
gs1_symbology=gs1_symbology,
)
def parse(
value: str,
*,
rcn_region: Optional[RcnRegion] = None,
separator_chars: Iterable[str] = DEFAULT_SEPARATOR_CHARS,
) -> ParseResult:
"""Identify data format and parse data.
The current strategy is:
1. If Symbology Identifier prefix indicates a GTIN or GS1 Message,
attempt to parse and validate as that.
2. Else, if not Symbology Identifier, attempt to parse with all parsers.
Args:
value: The data to classify and parse.
rcn_region: The geographical region whose rules should be used to
interpret Restricted Circulation Numbers (RCN).
Needed to extract e.g. variable weight/price from GTIN.
separator_chars: Characters used in place of the FNC1 symbol.
Defaults to `<GS>` (ASCII value 29).
If variable-length fields in the middle of the message are
not terminated with a separator character, the parser might
greedily consume the rest of the message.
Returns:
A data class depending upon what type of data is parsed.
Raises:
ParseError: If parsing of the data fails.
"""
value = value.strip()
config = ParseConfig(
rcn_region=rcn_region,
separator_chars=separator_chars,
)
result = ParseResult(value=value)
# Extract Symbology Identifier
if value.startswith("]"):
result.symbology_identifier = SymbologyIdentifier.extract(value)
value = value[len(result.symbology_identifier) :]
# Select parsers
queue: ParseQueue = []
if result.symbology_identifier is not None:
if result.symbology_identifier.gs1_symbology in GS1Symbology.with_gtin():
queue.append((_parse_gtin, value))
if (
result.symbology_identifier.gs1_symbology
in GS1Symbology.with_ai_element_strings()
):
queue.append((_parse_gs1_message, value))
if not queue:
# If we're not able to select a subset based on Symbology Identifiers,
# run all parsers on the full value.
queue = [
(_parse_gs1_message, value),
(_parse_gtin, value),
(_parse_sscc, value),
(_parse_upc, value),
]
# Work through queue of parsers and the values to run them on. Any parser may
# add additional work to the queue. Only the first result for a field is kept.
while queue:
(parse_func, val) = queue.pop(0)
parse_func(val, config=config, queue=queue, result=result)
if result._has_result():
return result
else:
raise ParseError(f"Failed to parse {value!r}:\n{result._get_errors_list()}")
def test_gs1_symbology_with_ai_element_strings() -> None:
assert GS1Symbology.EAN_13 not in GS1Symbology.with_ai_element_strings()
assert GS1Symbology.GS1_128 in GS1Symbology.with_ai_element_strings()
def test_gs1_symbology_enum() -> None:
assert GS1Symbology("C1") == GS1Symbology.GS1_128
def test_gs1_symbology_with_gtin() -> None:
assert GS1Symbology.EAN_13 in GS1Symbology.with_gtin()
# Even though GS1-128 can contain a GTIN,
# it cannot be parsed with a pure GTIN parser.
assert GS1Symbology.GS1_128 not in GS1Symbology.with_gtin()
def parse(
value: str,
*,
rcn_region: Optional[RcnRegion] = None,
separator_chars: Iterable[str] = DEFAULT_SEPARATOR_CHARS,
) -> ParseResult:
"""Identify data format and parse data.
The current strategy is:
1. If Symbology Identifier prefix indicates a GTIN or GS1 Message,
attempt to parse and validate as that.
2. Else, if not Symbology Identifier, attempt to parse with all parsers.
Args:
value: The data to classify and parse.
rcn_region: The geographical region whose rules should be used to
interpret Restricted Circulation Numbers (RCN).
Needed to extract e.g. variable weight/price from GTIN.
separator_chars: Characters used in place of the FNC1 symbol.
Defaults to `<GS>` (ASCII value 29).
If variable-length fields in the middle of the message are
not terminated with a separator character, the parser might
greedily consume the rest of the message.
Returns:
A data class depending upon what type of data is parsed.
Raises:
ParseError: If parsing of the data fails.
"""
value = value.strip()
result = ParseResult(value=value)
# Extract Symbology Identifier
if value.startswith("]"):
result.symbology_identifier = SymbologyIdentifier.extract(value)
value = value[len(result.symbology_identifier):]
# Select parsers
parsers: List[ParserType] = []
if result.symbology_identifier is not None:
if (result.symbology_identifier.gs1_symbology
in GS1Symbology.with_gtin()):
parsers.append(Gtin)
if (result.symbology_identifier.gs1_symbology
in GS1Symbology.with_ai_element_strings()):
parsers.append(GS1Message)
if not parsers:
# If we're not able to select a subset based on Symbology Identifiers,
# run all parsers in the default order.
parsers = [Gtin, Sscc, GS1Message]
# Run all parsers in order
for parser in parsers:
if parser == Gtin:
try:
result.gtin = Gtin.parse(value, rcn_region=rcn_region)
except ParseError as exc:
result.gtin_error = str(exc)
if parser == Sscc:
try:
result.sscc = Sscc.parse(value)
except ParseError as exc:
result.sscc_error = str(exc)
if parser == GS1Message:
try:
result.gs1_message = GS1Message.parse(
value,
rcn_region=rcn_region,
separator_chars=separator_chars,
)
except ParseError as exc:
result.gs1_message_error = str(exc)
else:
ai_00 = result.gs1_message.get(ai="00")
if ai_00 is not None:
# GS1 Message contains an SSCC
result.sscc = ai_00.sscc
# Clear error from parsing full value a SSCC.
result.sscc_error = None
ai_01 = result.gs1_message.get(ai="01")
if ai_01 is not None:
# GS1 Message contains a GTIN.
result.gtin = ai_01.gtin
# Clear error from parsing full value as GTIN.
result.gtin_error = None
if result._has_result():
return result
else:
raise ParseError(
f"Failed to parse {value!r}:\n{result._get_errors_list()}")