def analyze_term(self, overlookSet):
downOverlookSet = overlookSet[:]
V_term = VN.create(const.TERM)
factor = self.analyze_factor(overlookSet)
V_term.append(factor)
while self.pointer.isStarOperator():
star = self.pointer
self.getsym()
factor = self.analyze_factor(overlookSet)
V_term.append(star).append(factor)
self.emit(Instruction.create(star))
# 此处结束后没有检查！！！直接返回
return self.checkEmpty(V_term)
def analyze_condition(self, overlookSet = [const.R_BRACE]):
downOverlookSet = overlookSet[:]
V_condition = VN.create(const.CONDITION)
expression = self.analyze_expression(overlookSet)
V_condition.append(expression)
if self.pointer.isRelationOperator():
relationOperator = self.pointer
V_condition.append(relationOperator)
self.getsym()
V_condition.append(self.analyze_expression(overlookSet))
# 结束后将逻辑运算符入栈
self.emit(Instruction.create(relationOperator))
# 这里结束后没有检查，直接返回
return self.checkEmpty(V_condition)
def analyze_expression(self, overlookSet):
downOverlookSet = overlookSet[:]
V_expression = VN.create(const.EXPRESSION)
plus = False
# 如果开头就有符号，那么肯定是 -x 或者 +x ，默认操作数为0
if self.pointer.isPlusOperator():
plus = self.pointer
V_expression.append(plus)
self.getsym()
# 操作数 0 入栈
self.emit(Instruction(Instruction.LOC, '0', False))
term = self.analyze_term(overlookSet)
# 如果有操作符，那么生成加或减指令
self.emit(Instruction.create(plus))
V_expression.append(term)
while self.pointer.isPlusOperator():
plus = self.pointer
self.getsym()
term = self.analyze_term(overlookSet)
V_expression.append(plus).append(term)
self.emit(Instruction.create(plus))
# 此处结束后没有检查！！！直接返回
return self.checkEmpty(V_expression)