def Expression_ST(self): # 7. Expression = ["+"|"-"] Term {("+"|"-") Term}
tmpStartPos = self.curPos
op = None
zero_num_node = Node.Number(None, 0, tmpStartPos, tmpStartPos,
self.myErrHandler)
if self.current.Type == "keyword" and self.current.Value_Str in [
"+", "-"
]:
op = self.match(["+", "-"])
ret_node = self.Term_ST()
tmpEndPos = self.curPos - 1
if op == "-":
if isinstance(ret_node, Node.Number):
ret_node = self.Constant_Folding(op, zero_num_node, ret_node,
tmpStartPos, tmpEndPos,
self.myErrHandler)
else:
ret_node = Node.Binary(op, zero_num_node, ret_node,
tmpStartPos, tmpEndPos,
self.myErrHandler)
while self.current.Type == "keyword" and self.current.Value_Str in [
"+", "-"
]:
op = self.match(["+", "-"])
Right_node = self.Term_ST()
tmpEndPos = self.curPos - 1
if isinstance(ret_node, Node.Number) and isinstance(
Right_node, Node.Number): # Constant folding
ret_node = self.Constant_Folding(op, ret_node, Right_node,
tmpStartPos, tmpEndPos,
self.myErrHandler)
else:
ret_node = Node.Binary(op, ret_node, Right_node, tmpStartPos,
tmpEndPos, self.myErrHandler)
return ret_node
def Term_ST(self): # 8. Term = Factor {("*"|"DIV"|"MOD") Factor}
tmpStartPos = self.curPos
ret_node = self.Factor_ST()
while self.current.Type == "keyword" and self.current.Value_Str in [
"*", "DIV", "MOD"
]:
op = self.match(["*", "DIV", "MOD"])
Right_node = self.Factor_ST()
tmpEndPos = self.curPos - 1
if isinstance(ret_node, Node.Number) and isinstance(
Right_node, Node.Number): # Constant folding
ret_node = self.Constant_Folding(op, ret_node, Right_node,
tmpStartPos, tmpEndPos,
self.myErrHandler)
else:
ret_node = Node.Binary(op, ret_node, Right_node, tmpStartPos,
tmpEndPos, self.myErrHandler)
return ret_node