实验4-LR(1)分析法.doc
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河南工业大学实验报告
课程名称编译原理_实验项目实验四LR
(1)分析法
院系____信息科学与工程学院____专业班级计科F1402班
姓名苏朋辉学号201416010211
指导老师侯惠芳日期2017.5.6
批改日期成绩
一.实验目的
1.掌握LR
(1)分析法的基本原理
2.掌握LR
(1)分析表的构造方法
3.掌握LR
(1)驱动程序的构造方法
二.实验内容及要求
构造LR
(1)分析程序,利用它进行语法分析,判断给出的符号串是否为该文法识别的句子,了解LR(K)分析方法是严格的从左向右扫描,和自底向上的语法分析方法。
根据某一文法编制调试LR
(1)分析程序,以便对任意输入的符号串进行分析。
本次实验的目的主要是加深对LR
(1)分析法的理解。
程序输入/输出示例:
对下列文法,用LR
(1)分析法对任意输入的符号串进行分析:
(1)E->E+T
(2)E->E—T
(3)T->T*F
(4)T->T/F
(5)F->(E)
(6)F->i
输出的格式如下:
(1)LR
(1)分析程序,编制人:
姓名,学号,班级
(2)输入一以#结束的符号串(包括+—*/()i#):
在此位置输入符号串
(3)输出过程如下:
步骤
状态栈
符号栈
剩余输入串
动作
1
0
#
i+i*i#
移进
(4)输入符号串为非法符号串(或者为合法符号串)
备注:
(1)在“所用产生式”一列中如果对应有推导则写出所用产生式;如果为匹配终结符则写明匹配的终结符;如分析异常出错则写为“分析出错”;若成功结束则写为“分析成功”。
(2)在此位置输入符号串为用户自行输入的符号串。
注意:
1.表达式中允许使用运算符(+-*/)、分割符(括号)、字符i,结束符#;
2.如果遇到错误的表达式,应输出错误提示信息(该信息越详细越好);
3.对学有余力的同学,测试用的表达式事先放在文本文件中,一行存放一个表达式,同时以分号分割。
同时将预期的输出结果写在另一个文本文件中,以便和输出进行对照;
4.可采用的其它的文法。
三.实验过程
3.1代码如下:
#include
#include
#include
#include
usingnamespacestd;
//初始化预测分析表
stringaction[12][6]={
{"s5","error","error","s4","error","error"},
{"error","s6","error","error","error","acc"},
{"error","r2","s7","error","r2","r2"},
{"error","r4","r4","error","r4","r4"},
{"s5","error","error","s4","error","error"},
{"error","r6","r6","error","r6","r6"},
{"s5","error","error","s4","error","error"},
{"s5","error","error","s4","error","error"},
{"error","s6","error","error","s11","error"},
{"error","r1","r7","error","r1","r1"},
{"error","r3","r3","error","r3","r3"},
{"error","r5","r5","error","r5","r5"}
};
stringgo[12][3]={
{"1","2","3"},
{"error","error","error"},
{"error","error","error"},
{"error","error","error"},
{"8","2","3"},
{"error","error","error"},
{"error","9","3"},
{"error","error","10"},
{"error","error","error"},
{"error","error","error"},
{"error","error","error"},
{"error","error","error"},
};
charVt[6]={'i','+','*','(',')','#'};//终结符表
stringLR[6]={"E->E+T","E->T","T->T*F","T->F","F->(E)","F->i"};//LR文法
stackS;//状态栈
stackX;//符号栈
charinput[10];//输入字符
intnum(strings){//判断字符串中的数字
inti;
stringstr="";
for(intj=0;j{
if(s[j]>='0'&&s[j]<='9')str=str+s[j];
}
i=atoi(str.c_str());
returni;
}
voidpreview(char*c)
{
for(intj=0;c[j]!
='#';j++)
cout< cout<}
voidprint(inti,char*c)//剩余输入串的输出
{
for(intj=i;c[j-1]!
='#';j++)
cout< cout<<'\t';
}
intsame(chara){//用于查找终结符
for(inti=0;i<6;i++){
if(a==Vt[i])
returni;
}
return-1;
}
voidanalyse(){//**********分析程序
boolflag=true;//循环条件控制
intstep=1,point=0,state=0;//步骤、指针、状态
charch1,ch2;
intm,n,l;//用于判断终结符,分析表,表达式右部的长度
stringstr1;//用于判断对应分析表中的符号
stringstr2="#",str3="0";//记录符号栈的所有元素
cout<<"姓名:
苏朋辉学号:
201416010211班级:
计科F1402班"< cout<<"请输入要规约的字符串,并以#号结束:
"< cin>>input;
cout<<"您输入的字符串为:
";
preview(input);
X.push('#');
S.push(0);
cout<<"步骤"<<'\t'<<"状态栈"<<'\t'<<"符号栈"<<'\t'<<"输入串"<<'\t'<<"动作"< cout< print(point,input);
cout<<"初始化"< while(flag){//************进入循环
state=S.top();
ch1=input[point];
m=same(ch1);
str1=action[state][m];
//***********移进动作
if(str1[0]=='s'){
n=num(str1);
S.push(n);
X.push(ch1);
str2=str2+ch1;
ch2=n+48;
str3=str3+ch2;
point++;
cout< print(point,input);
cout<'<<"移进"< }
elseif(str1[0]=='r'){//**********归约动作
n=num(str1);
l=LR[n-1].length()-3;
for(inti=1;i<=l;i++)
{
S.pop();
str3=str3.substr(0,str3.length()-1);
X.pop();
str2=str2.substr(0,str2.length()-1);
}
X.push(LR[n-1][0]);
str2=str2+LR[n-1][0];
state=S.top();
if(LR[n-1][0]=='E')
{
S.push(num(go[state][0]));
ch2=num(go[state][0])+48;
str3=str3+ch2;
}
elseif(LR[n-1][0]=='T')
{
S.push(num(go[state][1]));
ch2=num(go[state][1])+48;
str3=str3+ch2;
}
elseif(LR[n-1][0]=='F')
{
S.push(num(go[state][2]));
ch2=num(go[state][2])+48;
str3=str3+ch2;
}
cout< print(point,input);
cout<'< }
//*********出错
elseif(str1=="error"){
cout<<"Error!
\n"<<"程序错误,分析结束!
"< flag=false;
}