def parseUnit(units, conversions, tokens, overwrite=False):
"""
Convert the next series of tokens into a unit
@param units: a map of unit symbols to unit objects to be modified
@param conversions: a map of unit symbols to scale factors to be modified
@param tokens: a list of tokens
"""
baseUnitMap = {}
# Handle base unit
sym = UC_Utils.parseSymbol(tokens)
if not overwrite and (sym in units):
raise UC_Common.FileFormatError(
f"Duplicate definition of unit '{sym}'")
# Handle derived unit
nextToken = UC_Utils.getNextToken(tokens)
if nextToken == UC_Common.MAP_DELIMITER:
scaleFactor = UC_Utils.parseFloat(tokens)
UC_Utils.getNextToken(tokens, UC_Common.SEP_DELIMITER)
baseUnitMap = parseBaseUnitMap(tokens)
conversions[sym] = scaleFactor
# Handle other tokens
elif nextToken != UC_Common.END_DELIMITER:
raise UC_Common.FileFormatError(
f"Expected delimiter; received '{nextToken}'")
# Create unit
units[sym] = UC_Unit.Unit(sym, baseUnitMap)
def parsePrefixMapping(prefixes, tokens, base, overwrite=False):
"""
Convert the next series of tokens into a prefix-exponent pair
@param prefixes: the prefix-exponent map to modify
@param tokens: a list of tokens
@param base: the base for the exponent
"""
prefix = UC_Utils.getNextToken(tokens)
if not overwrite and (prefix in prefixes):
raise UC_Common.FileFormatError(
f"Duplicate definition of prefix '{prefix}'")
prefixes[prefix] = (base, Decimal(UC_Utils.parseInt(tokens)))