编译原理实验二语法分析程序设计与实现

最新推荐文章于 2024-11-14 23:02:33 发布

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最新推荐文章于 2024-11-14 23:02:33 发布 · 1.6w 阅读

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该实验旨在通过SLR1方法设计和实现一个语法分析程序，对算术表达式的简化子集进行语法检查。实验内容包括设计程序流程，构建分析表，处理正确和错误的输入表达式。程序需展示每步分析过程，输出分析结果或错误信息。

一、实验目的

任选一种有代表性的语法分析方法，如算符优先法、递归下降法、LL(1)、SLR(1)、LR(1)等，通过设计、编制、调试实现一个典型的语法分析程序，对实验一所得扫描器提供的单词序列进行语法检查和结构分析，实现并进一步掌握常用的语法分析方法。

二、基本实验内容与要求

选择对各种常见高级程序设计语言都较为通用的语法结构——算术表达式的一个简化子集——作为分析对象，根据如下描述其语法结构的 BNF 定义G2[<算术表达式>]，任选一种学过的语法分析方法，针对运算对象为无符号常数和变量的四则运算，设计并实现一个语法分析程序。

G2[<算术表达式>]： <算术表达式> → <项> | <算术表达式>+<项> | <算术表达式>-<项> <项> → <因式> |<项><因式> | <项>/<因式> <因式> → <运算对象> | (<算术表达式>)
若将语法范畴<算术表达式>、<项>、<因式>和<运算对象>分别用 E、T、F 和 i 代表，则 G2 可写成：
G2[E]：E → T | E+T | E-T T → F | TF | T/F F → i | (E)

输入：由实验一输出的单词串，例如：UCON，PL，UCON，MU，ID ······
输出：若输入源程序中的符号串是给定文法的句子，则输出“RIGHT”，并且给出每一步分析过程；若不是句子，即输入串有错误，则输出“ERROR”，并且显示分析至此所得的中间结果，如分析栈、符号栈中的信息等，以及必要的出错说明信息。
要求:
1、确定语法分析程序的流程图，同时考虑相应的数据结构，编写一个语法分析源程序。
2、将词法、语法分析合在一起构成一个完整的程序，并调试成功。3、供测试的例子应包括符合语法规则的语句，及分析程序能判别的若干错例。对于所输入的字符串，不论对错，都应有明确的信息输出。

采用SLR1分析方法，首先将给定文法的SLR1分析表手工画出，存入到程序中，然后进行语法分析程序的实现。
在这里插入图片描述

四、源程序

#include <iostream>
#include <string>
#include <iomanip>
#include <cstring>
#include <fstream>
#include <stdio.h>
#include <cassert>
#include <vector>
//#define _CRT_SECURE_NO_WARNINGS
using namespace std;
/*
begin	BEGIN	1
end		END		2
if		IF		3
then	THEN	4
else	ELSE	5
while	WHILE	6
do		DO		7
标识符	ID		8
浮点常数UCON	9
<		LT		10
<=		LE		11
==		EQ		12
<>		NE		13
>		GT		14
>=		GE		15
=		IS		16
+		PL		17
-		MI		18
*		MU		19
/		DI		20
(		LP		21  新增加的左括号
)		RP		22  新增加的右括号
*/


const char* table1[] = {
   
    " ","begin","end","if","then","else","while","do" };
const char* table2[] = {
   
    " ","BEGIN","END","IF","THEN","ELSE","WHILE","DO","ID","UCON","LT","LE","EQ","NE","GT","GE","IS","PL","MI","MU","DI","LP","RP" };
char TOKEN[20];//用来依次存放一个单词词文中的各个字符。
char str[50];//存放词法分析后的表达式，将输入的表达式转变成只含有i和运算符的表达式
int len = 0;//词法分析后表达式的长度

//action表   char vt[8] = { '(',')','+','-','*','/','i','#' };
string action[16][8] = {
   
    {
   
   "s4","null","null" ,"null" ,"null","null","s5" , "null" },
					{
   
   "null","null","s6","s7","null","null","null","acc"},
					{
   
   "null","r3","r3","r3","s8","s9","null","r3"} ,
					{
   
   "null","r6","r6","r6","r6","r6","null","r6"},
					{
   
   "s4","null","null","null","null","null","s5","null"},
					{
   
   "null","r8","r8","r8","r8","r8","null","r8"},
					{
   
   "s4","null","null","null","null","null","s5","null"},
					{
   
   "s4","null","null","null","null","null","s5","null"},
					{
   
   "s4","null","null","null","null","null","s5","null"},
					{
   
   "s4","null","null","null","null","null","s5","null"},
					{
   
   "null","s15","s6","s7","null","null","null","null"} ,
					{
   
   "null","r1","r1","r1","s8","s9","null","r1"},
					{
   
   "null","r2","r2","r2","s8","s9","null","r2"} ,
					{
   
   "null","r4","r4","r4","r4","r4","null","r4"} ,
					{
   
   "null","r5","r5","r5","r5","r5","null","r5"} ,
					{
   
   "null","r7","r7","r7","r7","r7","null","r7"} };
//go表 char vn[3] = { 'E','T','F' };
int go[16][3]