编译原理：语法分析3-LR分析器

要求

代码

#语法分析，LR分析器
import pandas as pd
data={'id':['s5',' ',' ',' ','s5',' ','s5','s5',' ',' ',' ',' '],
      '+':[' ','s6','r2','r4',' ','r6',' ',' ','s6','r1','r3','r5'],
      '*':[' ',' ','s7','r4',' ','r6',' ',' ',' ','s7','r3','r5'],
      '(':['s4',' ',' ',' ','s4',' ','s4','s4',' ',' ',' ',' ',],
      ')':[' ',' ','r2','r4',' ','r6',' ',' ','s11','r1','r3','r5'],
      '$':[' ','acc','r2','r4',' ','r6',' ',' ',' ','r1','r3','r5'],
      'E':['1',' ',' ',' ','8',' ',' ',' ',' ',' ',' ',' '],
      'T':['2',' ',' ',' ','2',' ','9',' ',' ',' ',' ',' ',],
      'F':['3',' ',' ',' ','3',' ','3','10',' ',' ',' ',' ']}
SLR=pd.DataFrame(data,index=['0','1','2','3','4','5','6','7','8','9','10','11'])#SLR分析表
grammer=[' ','E→E+T','E→T','T→T*F','T→F','F→(E)','F→id']#文法的各个产生式
stk='0'#用字符串模拟栈
sub=""   #当前待处理记号被处理后的输入
def nextToken():#获取下一个词法记号
    global sub
    if(sub[0:2]=="id"):
         sub=sub[2:]
         return "id"
    else:
        s=sub[0:1]
        sub=sub[1:]
        return s
def showNextToken():#查看下一个词法记号
    global sub
    if (sub[0:2] == "id"):
        return "id"
    else:
        s = sub[0:1]
        return s
def top():#获取栈顶元素
    global stk
    if(stk[-2:]=='10'or stk[-2:]=='id' or stk[-2:]=='11'):
        return stk[-2:]
    else:
        return stk[-1:]
def pop():#弹出栈顶元素
    global stk
    if(stk[-2:]=='id'or stk[-2:]=='10'or stk[-2:]=='11'):
        stk=stk[:-2];
    else:
        stk=stk[:-1]
def push(s):#产生式→右边的逆序入栈
    global stk
    stk=stk+s
def rightlenth(s):#计算产生式→右边的长度
    index=s.find('→')
    ss=s[index+1:]
    if ss=='id':
        return 1
    else:
        return len(s[index+1:])
def leftPro(s):#计算产生式→左边的非终结符
    index = s.find('→')
    return s[:index]
def handle(t,head):#分析程序
    global SLR
    global stk
    action=SLR[head][t]
    #print("head=",head,'t=',t,"action=",action,end="  ")
    if action=='acc':
        print("%-10s"%stk,"%+9s"%sub,'    接受')
        return True
    else:
        if action[0]=='s':#要移进
            print("%-10s"%stk,"%+9s"%sub,"    移进")
            push(nextToken())
            push(action[1:])
        elif action[0]=='r':#要归约
            production=grammer[ord(action[1:])-ord('0')]
            print("%-10s"%stk,"%+9s"%sub,"    按",production,"归约")
            lenth=rightlenth(production)
            for i in range(lenth*2):
                pop()
            t=top()
            left=leftPro(production)
            push(left)
            push(SLR[left][t])
        else:#出错
            print("%-10s"%stk,"%+9s"%sub,end='')
            print("     error",end=',  ')
            print('多输入了一个',head)
            head=nextToken()
        return False
if __name__=='__main__':
    print("---------------------------------------")
    sub=input()
    sub+='$'
    print("---------------------------------------")
    print("%-8s"%"栈","%+8s"%"输入","    动作")
    while(True):
        b=handle(top(),showNextToken())
        if b==True:
            break
    print("---------------------------------------")

输入输出

• 有一定的错误处理功能，可以试试输入 idid+id 或者id**id