Python实现LR1文法的完整实例代码

一、使用步骤

 1.引入库（安装Python环境、PyQt、PyQt-tools)

from PyQt5 import QtCore, QtGui, QtWidgets
import sys
import datetime
from PyQt5.QtGui import QStandardItemModel, QStandardItem
from PyQt5.QtWidgets import QHeaderView
from collections import defaultdict
import numpy as np

2.全局变量

#text = "E -> E + T \nE -> T\nT -> T * F\nT -> F\nF ->(E)\nF -> i"
#text = "S -> BB\nB -> aB\nB -> b"
my_dict = defaultdict(list)#记录各个终结符的产生式
my_dicts = defaultdict(list)#代表每组项目，暂时存储
VNT = []
VT = set([])
MAX = 50 #生成最多的项目集个数
Inum = 0 #记录项目集的个数
end = [] #记录，上一个状态数，通过的字符，下一个状态数[最终结果]
numset = []#列表，修订状态数 
endstate = [] #最终存储项目集镞 [最终结果]
guiyue = [] #记录每条文法

3.完整代码

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'LR1.ui'
#
# Created by: PyQt5 UI code generator 5.15.1
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again. Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets
import sys
import datetime
from PyQt5.QtGui import QStandardItemModel, QStandardItem
from PyQt5.QtWidgets import QHeaderView
from collections import defaultdict
import numpy as np
#text = "E -> E + T \nE -> T\nT -> T * F\nT -> F\nF ->(E)\nF -> i"
#text = "S -> BB\nB -> aB\nB -> b"
my_dict = defaultdict(list)#记录各个终结符的产生式
my_dicts = defaultdict(list)#代表每组项目，暂时存储
VNT = []
VT = set([])
MAX = 50 #生成最多的项目集个数
Inum = 0 #记录项目集的个数
end = [] #记录，上一个状态数，通过的字符，下一个状态数[最终结果]
numset = []#列表，修订状态数 
endstate = [] #最终存储项目集镞 [最终结果]
guiyue = [] #记录每条文法
def isTerminal(c): # 若c介于A-Z之间则认为是非终结符(注意添加 self参数)
  if c < 'A' or c > 'Z':
   return True
  else:
   return False
def SplitText(text): # 把文法中E->A|B 切分为E->A和E->B
 mytext = ""
 for i in text:
  if(i != ' '):#删除字符串的空格
   mytext += i;
 i = mytext.split('\n')
 guiyue.append(text[0]+"'->"+text[0])
 for j in i:
  if(VNT.count(j[0])==0):#没出现过的终结符
   VNT.append(j[0]) 
  for k in range(1,len(j)):
   if(j[k]=='-' and j[k+1]=='>'):
    k = k+2
    break
  guiyue.append(j)
  my_dict[j[0]].append(j[k:])
def getFirst(mylist):#计算目标字符串的Frist集
 Zlist = []
 for i in mylist:
  if(i not in VNT):
   Zlist.append(i)
   return Zlist
  else:
   for j in my_dict[i]: #遍历非终结符的产生式
    #print(j)
    if(j[0] == i):
     continue
    time = 0
    for ch in j:
     if(ch not in VNT):
      Zlist.append(ch)
      break
     else:
      Firstlist = getFirst(ch)#递归得到Frist集
      if 'ε' in Firstlist: # Firstlist其实是指一个list
        time += 1
      else:
       for vi in Firstlist:
        Zlist.append(vi)
    if(time == len(j)):
     Zlist.append('ε')
   return Zlist

def getSymbol(mystr):#根据Frist集得到下一个状态的展望符
 for i in range(0,len(mystr)):
  if(mystr[i] =='.'):
   mylist = list(mystr[i+2:])
   break
 Zlist = ['#']
 if(mylist[0]==','):
  mylist = mylist[1:]
 if(mylist[0]=='#'):
  VT.add('#')
  return Zlist
 a = getFirst(mylist)
 VT.update(set(a))
 return a #存储展望符
#print(getSymbol('E->.E+T,#'))#验证展望符是否正确

def CLOSURE(mystr,num): #用于项目集内容的补充
 my_dicts[num].append(mystr) #先加上它本身
 zhanwang = getSymbol(mystr)#再计算展望符
 for i in range(0,len(mystr)):
  if(mystr[i] =='.'):
   ch = mystr[i+1]
 if(ch in VNT):
  for j in range(0,len(my_dict[ch])):
   ch2 = my_dict[ch][j]
   for k in range(0,len(zhanwang)):
    mystr = ch+"->."+ch2+","+zhanwang[k]
    if(my_dicts[num].count(mystr)==0):
     my_dicts[num].append(mystr)
    if(ch2[0] in VNT):
     for ss in my_dict[ch2[0]]:
      zhanwangs = getSymbol(mystr)
      for kk in range(0,len(zhanwangs)):
       mystr2 = ch2[0]+"->."+ss+","+zhanwangs[kk]
       if(my_dicts[num].count(mystr2)==0):
        CLOSURE(mystr2,num)
   
 else:
  return
def deleteI(delnum): #删除重复状态
 for i in delnum:
  del my_dicts[i]
 
def DFA(mynum):
 newstr = [] 
 command = dict()
 global Inum
 for fs in my_dicts[mynum]: #用字典存储 目标字符和状态集序号
  for i in range(0,len(fs)):
   if(fs[i]=='.'):
    if(fs[i+1]==','):
     break
    else:
     if(newstr.count(fs[i+1])==0):
      newstr.append(fs[i+1])
      Inum += 1
      command[fs[i+1]] = Inum   
 for fs in my_dicts[mynum]:
  for i in range(0,len(fs)):
   if(fs[i]=='.'):
    if(fs[i+1]==','):
     break
    else:
     mynums = command[fs[i+1]]
     s1 = list(fs)
     s1[i] = s1[i+1]
     s1[i+1]='.'
     sq = ''.join(s1) #巧妙实现字符串的替换
     CLOSURE(sq,mynums) #生成新的状态集
 #print(command)
 delnum = []
 for key,value in command.items():
  for j in range(0,value):
   if(set(my_dicts[j]) == set(my_dicts[value])):
    command[key] = j #修改状态序号
    delnum.append(value)
 #print(delnum)
 deleteI(delnum)
 for key,value in command.items():
  #print(mynum,'(',key,')->',value)
  end.append([mynum,key,value])
  numset.append(mynum)
  numset.append(value) #利用集合特性，修订状态数     

class Ui_Form(object):
 def setupUi(self, Form):
  Form.setObjectName("Form")
  Form.resize(994, 824)
  self.textBrowser = QtWidgets.QTextBrowser(Form)
  self.textBrowser.setGeometry(QtCore.QRect(520, 770, 461, 51))
  self.textBrowser.setObjectName("textBrowser")
  self.textBrowser_2 = QtWidgets.QTextBrowser(Form)
  self.textBrowser_2.setGeometry(QtCore.QRect(25, 771, 421, 41))
  self.textBrowser_2.setObjectName("textBrowser_2")
  self.label = QtWidgets.QLabel(Form)
  self.label.setGeometry(QtCore.QRect(460, 770, 51, 41))
  self.label.setObjectName("label")
  self.tabWidget = QtWidgets.QTabWidget(Form)
  self.tabWidget.setGeometry(QtCore.QRect(20, 240, 941, 521))
  self.tabWidget.setObjectName("tabWidget")
  self.First = QtWidgets.QWidget()
  self.First.setAccessibleName("")
  self.First.setObjectName("First")
  self.tableView = QtWidgets.QTableView(self.First)
  self.tableView.setGeometry(QtCore.QRect(10, 10, 911, 471))
  self.tableView.setObjectName("tableView")
  self.tabWidget.addTab(self.First, "")
  self.Analyse = QtWidgets.QWidget()
  self.Analyse.setObjectName("Analyse")
  self.tableView_2 = QtWidgets.QTableView(self.Analyse)
  self.tableView_2.setGeometry(QtCore.QRect(10, 10, 911, 471))
  self.tableView_2.setObjectName("tableView_2")
  self.tabWidget.addTab(self.Analyse, "")
  self.Process = QtWidgets.QWidget()
  self.Process.setObjectName("Process")
  self.tableView_3 = QtWidgets.QTableView(self.Process)
  self.tableView_3.setGeometry(QtCore.QRect(10, 10, 911, 471))
  self.tableView_3.setObjectName("tableView_3")
  self.tabWidget.addTab(self.Process, "")
  self.States = QtWidgets.QWidget()
  self.States.setObjectName("States")
  self.textBrowser_3 = QtWidgets.QTextBrowser(self.States)
  self.textBrowser_3.setGeometry(QtCore.QRect(10, 10, 911, 471))
  self.textBrowser_3.setObjectName("textBrowser_3")
  self.tabWidget.addTab(self.States, "")
  self.label_2 = QtWidgets.QLabel(Form)
  self.label_2.setGeometry(QtCore.QRect(40, 10, 51, 41))
  self.label_2.setObjectName("label_2")
  self.textEdit = QtWidgets.QTextEdit(Form)
  self.textEdit.setGeometry(QtCore.QRect(33, 46, 441, 181))
  self.textEdit.setObjectName("textEdit")
  self.textEdit.setText("E -> E + T \nE -> T\nT -> T * F\nT -> F\nF ->(E)\nF -> i")
 #初始化，编译原理测试数据
  #self.textEdit.setText("S -> BB\nB -> aB\nB -> b")
  self.lineEdit = QtWidgets.QLineEdit(Form)
  self.lineEdit.setGeometry(QtCore.QRect(640, 200, 271, 41))
  self.lineEdit.setObjectName("lineEdit")
  self.lineEdit.setText("i*i+i#")
 #初始化，编译原理测试数据
  self.label_3 = QtWidgets.QLabel(Form)
  self.label_3.setGeometry(QtCore.QRect(550, 200, 81, 41))
  self.label_3.setObjectName("label_3")
  self.pushButton = QtWidgets.QPushButton(Form)
  self.pushButton.setGeometry(QtCore.QRect(650, 110, 251, 71))
  self.pushButton.setObjectName("pushButton")
  self.pushButton.clicked.connect(self.Runs) # 将按钮与函数Runs()绑定,启动主程序
  self.retranslateUi(Form)
  self.tabWidget.setCurrentIndex(0)
  QtCore.QMetaObject.connectSlotsByName(Form)

 def retranslateUi(self, Form):
  _translate = QtCore.QCoreApplication.translate
  Form.setWindowTitle(_translate("Form", "LR(1)文法"))
  self.label.setText(_translate("Form", "分 析："))
  self.tabWidget.setTabText(self.tabWidget.indexOf(self.First), _translate("Form", "FIRST集"))
  self.tabWidget.setTabText(self.tabWidget.indexOf(self.Analyse), _translate("Form", "分 析 表"))
  self.tabWidget.setTabText(self.tabWidget.indexOf(self.Process), _translate("Form", "分 析 过 程"))
  self.tabWidget.setTabText(self.tabWidget.indexOf(self.States), _translate("Form", "项 目 集 族"))
  self.label_2.setText(_translate("Form", "文 法："))
  self.label_3.setText(_translate("Form", "输 入 框"))
  self.pushButton.setText(_translate("Form", "运 行 程 序"))
 def Runs(self):
  global VNT,VT,numset,Inum,endstate,guiyue,my_dict,my_dicts,end#初始化
  Inum = 0 #记录项目集的个数
  my_dict = defaultdict(list)#记录各个终结符的产生式
  my_dicts = defaultdict(list)#代表每组项目，暂时存储
  VNT = []
  VT = set([])
  end = [] #记录，上一个状态数，通过的字符，下一个状态数
  numset = []#列表，修订状态数 [最终结果]
  endstate = [] #最终存储项目集镞 [最终结果]
  guiyue = [] #记录每条文法
  times = datetime.datetime.now()
  times_str = times.strftime('  %Y-%m-%d %H:%M:%S')
  self.textBrowser_2.setText('运 行 时 间：'+times_str)
  text = self.textEdit.toPlainText()
  SplitText(text)#1 处理文法
  input0 = text[0]+"'->."+text[0]+',#' #输入第一个项目
  CLOSURE(input0,0) #2 生成I0项目集
  for i in range(0,MAX):
   DFA(i)
  numset = list(set(numset))#3 消除重复元素
  for i in end:#4 修订状态过程
   i[0] = numset.index(i[0])
   i[2] = numset.index(i[2])
  for i in range(0,len(my_dicts)):
   if my_dicts[i] != []:
    endstate.append(my_dicts[i])#5 将修订后的项目集族写入新的列表
  #将项目集族写入图形界面
  self.textBrowser_3.setText("\t\t\tLR(1)项 目 集 族\n")
  j = 0
  for i in endstate:
   self.textBrowser_3.append('I'+str(j)+': '+str(i)+'\n')
   j += 1
  #将Frist集写入图形界面
  self.model = QStandardItemModel(len(VNT), 5)
  label_y = []
  for s in VNT:
   label_y.append(s)
  self.model.setVerticalHeaderLabels(label_y)
  for row in range(len(VNT)):
    flist = [VNT[row]]#First集要输入一个列表
    Flist = list(set(getFirst(flist)))
    for column in range(len(Flist)):
     item = QStandardItem(Flist[column])
     self.model.setItem(row, column, item)
  self.tableView.horizontalHeader().setStretchLastSection(True)
  self.tableView.horizontalHeader().setSectionResizeMode(QHeaderView.Stretch)
  self.tableView.setModel(self.model)
  #构造分析表，写入图形界面
  VT.discard('#')
  VT = list(VT) #先删除#
  VT.append('#')#想让#在ACTION表最后一列
  label_x = ['状 态']+VT+VNT
  self.model2 = QStandardItemModel(len(endstate),len(VNT)+len(VT))
  self.model2.setHorizontalHeaderLabels(label_x)
  label_y = []
  for i in range(0,len(endstate)):
   label_y.append(str(i))
  self.model2.setVerticalHeaderLabels(label_y)
  ACTION = [['0'] * len(VT) for i in range(len(endstate))] #存储分析表内容，为分析过程做准备
  GOTO = [['0'] * len(VNT) for i in range(len(endstate))]
  for q in end: #移进动作
   if(q[1] not in VNT):
    ss = 's'+str(q[2])
    ACTION[int(q[0])][VT.index(q[1])] = ss
   else:
    ss = str(q[2])
    GOTO[int(q[0])][VNT.index(q[1])] = ss
   item = QStandardItem(ss)
   self.model2.setItem(int(q[0]),label_x.index(q[1]),item)
  endstr = text[0]+"'->"+text[0]+'.,#' #终结标志
  for i in range(len(endstate)):#规约动作
   for j in range(len(endstate[i])):
    for k in range(len(endstate[i][j])):
     if(endstate[i][j][k]=='.'):
      if(endstate[i][j][k+1]== ','):
       #print(guiyue)
       ii = guiyue.index(endstate[i][j][:k])
       item = QStandardItem("r"+str(ii))
       ACTION[i][VT.index(endstate[i][j][k+2])] = "r"+str(ii)
       self.model2.setItem(i,label_x.index(endstate[i][j][k+2]),item)
   if(endstate[i][0] == endstr):
    item = QStandardItem("acc")#结束
    self.model2.setItem(i,label_x.index('#'),item)    
  self.tableView_2.horizontalHeader().setStretchLastSection(True)
  self.tableView_2.horizontalHeader().setSectionResizeMode(QHeaderView.Stretch)
  self.tableView_2.setModel(self.model2)
  self.model3 = QStandardItemModel(32,4)
  #print(ACTION)
  #print(GOTO)
  mystate = [0]#状 态
  stack = '#' #符 号
  inputstr = self.lineEdit.text()#输 入 串
  label_x = ['状 态', '符 号', '输 入 串', '动 作']
  self.model3.setHorizontalHeaderLabels(label_x)
  tabnum = 0
  while(1):
   self.model3.setItem(tabnum,0,QStandardItem(str(mystate)))
   self.model3.setItem(tabnum,1,QStandardItem(stack))
   self.model3.setItem(tabnum,2,QStandardItem(inputstr))
   tabnum += 1
   if(inputstr[0] not in VT):
    self.textBrowser.setText('报 错！')
   else:
    ch = ACTION[mystate[-1]][VT.index(inputstr[0])]#读取action值
   if(ch =='r0'):#本质就是acc
    self.textBrowser.setText('分 析 成 功！')
    break
   if(ch == '0'):
    self.textBrowser.setText('报 错！')
    break
   if(ch[0] == 's'):
    mystate.append(int(ch[1:]))#状态加一个
    stack += inputstr[0]#移进
    inputstr = inputstr[1:]#相当于删除第一个元素
   if(ch[0] == 'r'):
    gylist = guiyue[int(ch[1:])].split('->')
    g1 = str(gylist[1])[::-1]
    g0 = str(gylist[0])[::-1]
    gstack = stack[::-1]#逆序解决规约问题
    gstack = gstack.replace(g1,g0,1)
    stack = gstack[::-1]#完成规约任务
    strlen = len(gylist[1]) #计算长度
    for i in range(strlen):
     mystate.pop()#连续出栈
    mystate.append(int(GOTO [mystate[-1]] [VNT.index(gylist[0])] ))
  self.tableView_3.horizontalHeader().setStretchLastSection(True)
  self.tableView_3.horizontalHeader().setSectionResizeMode(QHeaderView.Stretch)
  self.tableView_3.setModel(self.model3)
if __name__ == "__main__":
 app = QtWidgets.QApplication(sys.argv)
 Form = QtWidgets.QWidget()
 ui = Ui_Form()
 ui.setupUi(Form)
 Form.show()
 sys.exit(app.exec_())

4.运行结果截图

5.学会自己看注释

6.用数据代码，为我爱的世界添砖加瓦

到此这篇关于Python实现LR1文法的文章就介绍到这了,更多相关Python实现LR1文法内容请搜索猪先飞以前的文章或继续浏览下面的相关文章希望大家以后多多支持猪先飞！