python实现文法左递归的消除方法

import os
import tkinter as tk
import tkinter.messagebox
import tkinter.font as tf
zhuizhong = ""
wenfa = {"非左递归文法"}
xi_ = ""
huo = ""
window = tk.Tk()
window.title('消除左递归')
window.minsize(500,500)
#转换坐标显示形式为元组
def getIndex(text, pos):
return tuple(map(int, str.split(text.index(pos), ".")))
def zhijie(x,y):
if not len(y):
pass
else:
if x == y[0]:
wenfa.discard("非左递归文法")
#处理直接左递归
zuobian = y.split('|')
feizhongjie = []
zhongjie = []
for item in zuobian:
if x in item:
item = item[1:]
textt = str(item) + str(x) + "'"
feizhongjie.append(textt)
else:
text = str(item) + str(x) + "'"
zhongjie.append(text)
if not zhongjie:#处理A -  Ax的情况
zhongjie.append(str(x + "'"))
cheng = str(x) + " -  " + "|".join(zhongjie)
zi = str(x) + "'" + " -  " + "|".join(feizhongjie) + "|є"
text_output.insert('insert','直接左递归文法','tag1')
text_output.insert('insert','\n')
text_output.insert('insert',cheng,'tag2')
text_output.insert('insert','\n')
text_output.insert('insert',zi,'tag2')
'''
加上会判断输出非递归产生式，但会导致间接左递归不能删除多余产生式
else:
h ="不变： " + x + " -  " + y
text_output.insert('insert','非左递归文法','tag1')
text_output.insert('insert','\n')
text_output.insert('insert',h,'tag2')
'''
text_output.insert('insert','\n')
def zhijie2(x,y):
if not len(y):
pass
else:
if x == y[0]:
wenfa.discard("非左递归文法")
#处理直接左递归
zuobian = y.split('|')
feizhongjie = []
zhongjie = []
for item in zuobian:
if x in item:
item = item[1:]
textt = str(item) + str(x) + "'"
feizhongjie.append(textt)
else:
text = str(item) + str(x) + "'" 
zhongjie.append(text)
cheng = str(x) + " -  " + "|".join(zhongjie)
zi = str(x) + "'" + " -  " + "|".join(feizhongjie) + "|є"
text_output.insert('insert',"间接左递归文法",'tag1')
text_output.insert('insert','\n')
text_output.insert('insert',cheng,'tag2')
text_output.insert('insert','\n')
text_output.insert('insert',zi,'tag2')
text_output.insert('insert','\n')
def tihuan(xk,yi,yk):
yi_you = []
yi_wu =[]
yi_he = ""
yi_wuhe = ""
yi_zhong = ""
yi_feizhong = []
if xk in yi:
yk_replace = yk.split('|')
yi_fenjie = yi.split('|')#将含非终结与不含分开
for ba in yi_fenjie:
if xk in ba:
yi_you.append(ba)
else:
yi_wu.append(ba)
yi_he = "|".join(yi_you)
for item in yk_replace:
yi_zhong = yi_he.replace(xk,item)#替换
yi_feizhong.append(yi_zhong)
yi_wuhe = "|".join(yi_wu)#再合并
global zhuizhong
zhuizhong = "|".join(yi_feizhong) + "|" + yi_wuhe
#点击按钮后执行的函数
def changeString():
text_output.delete('1.0','end')
text = text_input.get('1.0','end')
text_list = list(text.split('\n'))#一行一行的拿文法
text_list.pop()
if not text_list[0]:
print(tkinter.messagebox.showerror(title = '出错了！',message='输入不能为空'))
else:
for cfg in text_list:
x,y = cfg.split('- ')#将文法左右分开
x = ''.join(x.split())#消除空格
y = ''.join(y.split())
if not (len(x) == 1 and x  = 'A' and x <= 'Z'):
pos = text_input.search(x, '1.0', stopindex="end")
result = tkinter.messagebox.showerror(title = '出错了！',
message='非上下文无关文法!坐标%s'%(getIndex(text_input, pos),))
# 返回值为：ok
print(result)
return 0
else:
zhijie(x,y)
for i in range(len(text_list)):
for k in range(i):
xi,yi = text_list[i].split('- ')
xi = ''.join(xi.split())#消除空格
yi = ''.join(yi.split())
xk,yk = text_list[k].split('- ')
xk = ''.join(xk.split())#消除空格
yk = ''.join(yk.split())
tihuan(xk,yi,yk)
tihuan(xk,zhuizhong,yk)
global xi_
xi_ = xi
zhijie2(xi_,zhuizhong)
for item in wenfa:
text_output.insert('insert',item,'tag1')  
#创建文本输入框和按钮
text_input = tk.Text(window, width=80, height=16)
text_output = tk.Text(window, width=80, height=20)
#简单样式
ft = tf.Font(family='微软雅黑',size=12)
text_output.tag_config("tag1",background="yellow",foreground="red",font=ft)
text_output.tag_config('tag2',font = ft)
#按钮
button = tk.Button(window,text="消除左递归",command=changeString,padx=32,pady=4,bd=4)
text_input.pack()
text_output.pack()
button.pack()
window.mainloop()