def analyze_sentenceWhile(self, overlookSet = [const.R_BRACE]):
downOverlookSet = [const.R_BRACE]
self.overlookSetAdd(downOverlookSet, const.R_PARENTHESIS)
V_sentenceWhile = VN.create(const.SENTENCE_LOOP)
V_sentenceWhile.append(self.pointer)
self.getsym()
whileBRInstruction = None
whileHeadLab = Instruction.generateLab()
if self.pointer.isL_Parenthesis():
V_sentenceWhile.append(self.pointer)
self.getsym()
# 为while头部设置lab标签
self.instructionStream.setLab(whileHeadLab)
V_sentenceWhile.append(self.analyze_condition(downOverlookSet))
if self.pointer.isR_Parenthesis():
V_sentenceWhile.append(self.pointer)
self.getsym()
# 条件分析结束后加入BRF指令
whileBRInstruction = Instruction(Instruction.BRF, Instruction.generateLab())
self.instructionStream.append(whileBRInstruction)
V_sentenceWhile.append(self.analyze_sentence(overlookSet))
# while中的语句分析结束后，加入BR指令，直接跳转回while头部
self.emit(Instruction(Instruction.BR, whileHeadLab))
else:
self.error(Error.GA_MISS_R_PARENTHESIS)
self.overlookToMarks(downOverlookSet)
else:
self.error(Error.GA_MISS_L_PARENTHESIS, self.pointer.previous)
self.overlookToMarks(downOverlookSet)
# while分析结束后，在其后的第一条语句添加lab标记
if whileBRInstruction:
self.instructionStream.setLab(whileBRInstruction.operator)
return self.checkEmpty(V_sentenceWhile)
def analyze_sentenceIf(self, overlookSet = [const.R_BRACE]):
downOverlookSet = overlookSet[:]
self.overlookSetAdd(downOverlookSet, const.R_PARENTHESIS)
self.overlookSetAdd(downOverlookSet, const.ELSE)
ifSentenceOverlookSet = overlookSet[:]
self.overlookSetAdd(ifSentenceOverlookSet, const.ELSE)
V_sentenceIf = VN.create(const.SENTENCE_CONDITION)
V_sentenceIf.append(self.pointer)
self.getsym()
if self.pointer.isL_Parenthesis():
V_sentenceIf.append(self.pointer)
self.getsym()
V_sentenceIf.append(self.analyze_condition(downOverlookSet))
if self.pointer.isR_Parenthesis():
# 分析完条件，加入比较跳转指令
headBRFInstruction = Instruction(Instruction.BRF, Instruction.generateLab())
self.emit(headBRFInstruction)
V_sentenceIf.append(self.pointer)
self.getsym()
if not self.pointer.isR_Else():
V_sentenceIf.append(self.analyze_sentence(ifSentenceOverlookSet))
else:
self.error(Error.GA_MISS_SENTENCE, self.pointer.previous, 'Gramma Analysis Error: A sentence between IF and ELSE is expected.')
if self.pointer.isR_Else():
V_sentenceIf.append(self.pointer)
self.getsym()
# 在if标记后的语句分析结束后，Else分析开始前,添加一条BR指令，
# 用于跳转到Else分析结束后的第一条指令
# 如果没有else部分，这条指令不存在
headBRInstruction = Instruction(Instruction.BR, Instruction.generateLab())
self.emit(headBRInstruction)
# if标记之后的语句分析结束后，加入lab标记，
# 使得在Else分析出的语句中的第一条语句获得lab标记
self.instructionStream.setLab(headBRFInstruction.operator)
V_sentenceIf.append(self.analyze_sentence(overlookSet))
# 对于存在Else分析的情况，在Else结束后的第一条语句后面添加BR标记
self.instructionStream.setLab(headBRInstruction.operator)
else:
# if标记之后的语句分析结束后，加入lab标记，
# 在没有else标记的情况下，if分析后的第一条语句也要加入lab标记
self.instructionStream.setLab(headBRFInstruction.operator)
else :
self.error(Error.GA_MISS_R_PARENTHESIS)
self.overlookToMarks(overlookSet)
else:
self.error(Error.GA_MISS_L_PARENTHESIS, self.pointer.previous)
self.overlookToMarks(overlookSet)
return V_sentenceIf