LL(1)语法分析

最新推荐文章于 2025-06-11 13:50:45 发布

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最新推荐文章于 2025-06-11 13:50:45 发布 · 4.1k 阅读

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LL(1)语法分析是一种自顶向下的方法，用于确定输入串的最左推导。通过构造first集合和follow集合来创建LL(1)分析表，进而实现对输入串的解析。文中涉及文法规则并提到了程序实现细节，参考自《龙书》的4.4.4节。

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LL（1）文法分析是自顶向下的分析方法，也可以被看作是输入串的最左推导过程，LL（1）中1的意思就是可以根据可以根据当前输入串中的一个字符来判断是由哪一个产生式产生。

下面给出文法：

E->Te

e->Ate | # (#代表空集)

T->Ft

t->MFt | #

F->i | (E)

i-> 0|1|2|...|9

A->+|-

M->*|/

首先要构造first集合与follow集合，根据集合做出LL（1）分析表

然后将分析表存到程序中，给定输入的串，来输出最左推导的过程，算法在龙书的4.4.4节

下面给出程序：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <stack>

using namespace std;

#define MAX 100
char c[8]={'i','(','+','-','*','/',')','#'};
char w[7]={'E','e','T','t','F','A','M'};
char mapp[7][8][5]=     {"Te","Te","%","%","%","%","%","%",
                        "%","%","ATe","ATe","%","%","#","#",
                        "Ft","Ft","%","%","%","%","%","%",
                        "%","%","#","#","MFt","MFt","#","#",
                        "i","(E)","%","%","%","%","%","%",
                        "%","%","+","