def scanNumber(self):
self.isDigit = False
self.wholePart = 0.0
self.fractionalPart = 0.0
self.fractionalMultiplier = 0.1
self.past_decimal = False
while self.EndExp is False and self.isDigitOrDecimal(self.CharNext):
if self.CharNext == '.':
if self.past_decimal:
raise CalcExceptions(
"badly formed number - multiple decimal points")
self.past_decimal = True
elif self.isDigitOrDecimal(self.CharNext):
self.isDigit = True
if self.past_decimal is False:
self.wholePart = int(self.wholePart) * 10 + int(
self.CharNext)
else:
self.fractionalPart += int(
self.CharNext) * self.fractionalMultiplier
self.fractionalMultiplier /= 10.0
self.advCursor()
if self.isDigit is False:
raise CalcExceptions(
"badly formed number - decimal point with no digits")
return self.wholePart + self.fractionalPart
def parse(self, tokens):
if len(tokens) == 1:
raise CalcExceptions("Parser received an empty token list.")
self.tokens = tokens
self.currentToken = self.tokens[0]
eTree = self.parseExpression()
if self.currentToken is not None:
raise CalcExceptions("Unconsumed tokens at end of expression.")
return eTree
def parseNumber(self):
if self.currentToken is None:
raise CalcExceptions(
'Reached end of tokens while expecting a number.')
if self.currentToken.getType() == TokenType.NUMBER_TOKEN:
value = self.currentToken.getValue()
self.consumeToken()
return expressionTree.NumberExpressionTree(value)
else:
raise CalcExceptions("Expected a number.")
def parseFactor(self):
if self.currentToken is None:
raise CalcExceptions(
'Reached end of tokens while expecting a number.')
factor = None
if self.currentToken.getType(
) == TokenType.PAREN_TOKEN and self.currentToken.getValue() == '(':
self.consumeToken()
factor = self.parseExpression()
if self.currentToken is None or self.currentToken.getValue(
) != ')':
raise CalcExceptions('Badly formed parenthesized expression.')
self.consumeToken()
elif self.currentToken.getType(
) == TokenType.OPERATOR_TOKEN and self.currentToken.getValue() == '~':
self.consumeToken()
subExpr = self.parseNumber()
factor = expressionTree.OperatorExpressionTree('~', None, subExpr)
else:
factor = self.parseNumber()
return factor