编译实验语法分析.docx

1、编译实验语法分析语法分析器实验报告院 系： 专 业： 小组成员： 学 号： 日 期： 一、实验目的根据给出的文法编制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。二、实验内容对已给语言文法，构造LR(1)分析表，编制语法分析程序，要求将错误信息输出到语法错误文件中，并输出分析句子的过程（显示栈的内容）LR（1）分析法的功能 ：LR（1）分析法的功能是利用LR（1）分析表，对输入符号串自下而上的分析过程。 LR（1）分析表的构造及分析过程。三实验文法 := . := := const ; | := = | , = := var ; | :=

2、 | , := procedure ; ; | := := | call | begin end | if then | while do | := | ; := odd | := = | | | = := | | := + | - := | := * | / := | | ( ) 注意： (1) 表示空串。. (2) 和 分别表示标识符和数。 简化0 PP1 PB2 BVS3 VaL;4 V5 Li6 LL,i7 Si_E8 SbTe9 SfDtS10 SwDdS11 S12 TS13 TT;S14 DERE15 Ri17 En18 E (E)P B V S E L T D Ravar bb

3、egin eend _:= I Fif Tthen Wwhile ddo n 空串的文法:实验环境：Microsoft Windows 7Microsoft Visual Studio 2010实验原理:构造LR（1）项集族的方法Setofltems CLOSURE(I) repeat for （I中的每个项AB，a for(G中的每个产生式B) for（FIRST（a）中的每个终结符号b） 将B，b加入到集合I中； Until不能向I中加入更多的项； return ISetofltems GOTO (I,X) 将J初始化为空集；for（I中的每一个项AX，a ） 将项AX，a加入到集合J中；

4、return CLOSURE(J)：Void items(G) 将C初始化为 CLOSURE( S S，$)； repeat for（C中的每一个项集I） for（每一个文法符号X） if（GOTO（I,X）非空且不在C中） 将GOTO（I，X）加入C中；until 不再有新的项集加入到C中；语法分析表： 实验流程图:实验结果：输入：beginwhile ab do b:=cend.输出：输入：beginwhile ab do b:=cend.输出：心得体会：完成本次实验，我们首先要根据题目中给出的文法，构造LR(1)项集族，之后构造LR(1)语法分析表。题目中给出的是pascal语言版的文法

5、，实验开始时我们也稍微学习了一下pascal语言的风格和定义方法。开发的C程序，把构造好的LR(1)语法分析表存入，用数组模拟栈的功能。对词法分析输出的语句，语法分析中，模拟字符的入栈，之后匹配语法分析表匹配出相应的ACTION动作，分析是移入操作还是归约操作。当为移入操作时需要更新栈中栈顶符号和栈顶状态号；当为归约操作时，要根据相应的产生式，把产生式右边的字符弹出栈，出栈字符的个数要根据产生式的长度来判断，状态号的出栈个数也要匹配出栈字符的个数。同时归约之后，要把产生式左边的终结符入栈，终结符入栈之后还要进行GOTO跳转。所谓的入栈操作就是数组的个数增加操作，出栈操作就是数组的减法操作。当时

6、栈操作是从栈顶开始的，所以每一个数组的最后一位（栈顶）要十分明确的处理好，以免发生模拟入栈、出栈错误。关键代码：class actionspublic: char action;/记录s或r等 int num;/记录下标act8030;void fenxibiao() int i = 0, j ; /先全部赋值为e,代表错误 for(i = 0; i = 78; i +) for(j = 0; j = 24; j +) actij.action = e; act00.action = s , act00.num = 4; act01.action = r , act01.num = 4; ac

7、t04.action = r , act04.num = 4; act05.action = r , act05.num = 4; act07.action = r , act07.num = 4; act015.action = r , act015.num = 4; act016.action = , act016.num = 1; act017.action = , act017.num = 2; act018.action = , act018.num = 3; act115.action = a , act115.num = 100; /a代表接收状态 act215.action =

8、 r , act215.num = 1; act31.action = s , act31.num = 7; act34.action = s , act34.num = 6; act35.action = s , act35.num = 8; act37.action = s , act37.num = 9; act315.action = r , act315.num = 11; act319.action = , act319.num = 5; act44.action = s , act44.num = 11; act421.action = , act421.num = 10; ac

9、t515.action = r , act515.num = 2; act63.action = s , act63.num = 12; act71.action = s , act71.num = 16; act72.action = r , act72.num = 11; act74.action = s , act74.num = 15; act75.action = s , act75.num = 17; act77.action = s , act77.num = 18; act710.action = r , act70.num = 11; act719.action = , ac

10、t719.num = 14; act722.action = , act722.num = 13; act84.action = s , act84.num = 21; act812.action = s , act812.num = 23; act814.action = s , act814.num = 22; act820.action = , act820.num = 20; act823.action = , act823.num = 19; act94.action = s , act94.num = 21; act912.action = s , act912.num = 23;

11、 act914.action = s , act914.num = 22; act920.action = , act920.num = 25; act923.action = , act923.num = 24; act109.action = s , act109.num = 27; act1010.action = s , act1010.num = 26; act119.action = r , act119.num = 5; act1110.action = r , act1110.num = 5; act124.action = s , act124.num = 29; act12

12、12.action = s , act1212.num = 31; act1214.action = s , act1214.num = 30; act1220.action = , act1220.num = 28; act132.action = s , act132.num = 32; act1310.action = s , act1310.num = 33; act142.action = r , act142.num = 12; act1410.action = r , act1410.num = 12; act153.action = s , act153.num = 34; a

13、ct161.action = s , act161.num = 16; act162.action = r , act162.num = 11; act164.action = s , act164.num = 15; act165.action = s , act165.num = 17; act167.action = s , act167.num = 18; act1610.action = r , act160.num = 11; act1619.action = , act1619.num = 14; act1622.action = , act1622.num = 35; act1

14、74.action = s , act174.num = 21; act1712.action = s , act1712.num = 23; act1714.action = s , act1714.num = 22; act1720.action = , act1720.num = 20; act1723.action = , act1723.num = 36; act184.action = s , act184.num = 21; act1812.action = s , act1812.num = 23; act1814.action = s , act1814.num = 22;

15、act1820.action = , act1820.num = 25; act1823.action = , act1823.num = 37; act196.action = s , act196.num = 38; act2011.action = s , act2011.num = 40; act2024.action = , act2024.num = 39; act2111.action = r , act2111.num = 16; act2211.action = r , act2211.num = 17; act234.action = s , act234.num = 42

16、; act2312.action = s , act2312.num = 44; act2314.action = s , act2314.num = 43; act2320.action = , act2320.num = 41; act246.action = s , act246.num = 45; act2511.action = s , act2511.num = 40; act2524.action = , act2524.num = 46; act261.action = r , act261.num = 3; act264.action = r , act264.num = 3

17、; act265.action = r , act265.num = 3; act267.action = r , act267.num = 3; act2615.action = r , act2615.num = 3; act274.action = s , act274.num = 47; act2815.action = r , act2815.num = 7; act2915.action = r , act2915.num = 16; act3015.action = r , act3015.num = 17; act314.action = s , act314.num = 42

18、; act3112.action = s , act3112.num = 44; act3114.action = s , act3114.num = 43; act3120.action = , act3120.num = 48; act3215.action = r , act3215.num = 8; act331.action = s , act331.num = 16; act332.action = r , act332.num = 11; act334.action = s , act334.num = 15; act335.action = s , act335.num = 1

19、7; act337.action = s , act337.num = 18; act3310.action = r , act330.num = 11; act3319.action = , act3319.num = 49; act3315.action = r , act3315.num = 28; act344.action = s , act344.num = 51; act3412.action = s , act3412.num = 53; act3414.action = s , act3414.num = 52; act3420.action = , act3420.num

20、= 50; act352.action = s , act352.num = 54; act3510.action = s , act3510.num = 33; act366.action = s , act366.num = 55; act378.action = s , act378.num = 56; act381.action = s , act381.num = 7; act384.action = s , act384.num = 6; act385.action = s , act385.num = 8; act387.action = s , act387.num = 9;

21、act3815.action = r , act3815.num = 11; act3819.action = , act3819.num = 57; act394.action = s , act394.num = 59; act3912.action = s , act3912.num = 61; act3914.action = s , act3914.num = 60; act3920.action = , act3920.num = 58; act404.action = r , act404.num = 15; act4012.action = r , act4012.num =

22、15; act4014.action = r , act4014.num = 15; act4113.action = s , act4113.num = 62; act4213.action = r , act4213.num = 16; act4313.action = r , act4313.num = 17; act444.action = s , act444.num = 42; act4412.action = s , act4412.num = 44; act4414.action = s , act4414.num = 43; act4420.action = , act4420.num = 62; act451.action = s , act451.num = 7; act454.action = s , act454.num = 6; act455.action = s , act455.num = 8; act457.action = s , act457.num = 9; act4515.action = r , act4515.num = 11; act4519.action = , act4519.num = 64; act464