程序与技术分享：C++写一个简单的解析器（分析C语言）

该方案实现了一个分析C语言的词法分析+解析。

注意：

1.简单语法，部分秕。它可以在本文法的基础上进行扩展，此过程使用自上而下LL(1)语法。

2.自己主动能达到求First 集和 Follow 集。

3.处终结符外（有些硬编码的成分），终结符的文法能够自己定义，也就是说读者能够自己定义文法。

4.为方便理解。C语言的文法描写叙述写成中文。

5.程序将词法分析和语法分析结合起来。词法分析的结果作为语法分析的输入。

6.终于结果在控制台显示的有：词法分析、First集、Follow集、Select集，在preciateResult.txt 中写入了语法分析结果。在preciateTable.txt 中写入了预測分析表。

7.文法的词素之间必须有空格分开。

项目结构例如以下：

文法例如以下：

wenfa.txt:

-> ( ) { }

-> | $

-> describe

-> type

->

-> | $

->

->

-> id

-> 【 】 | $

-> ( ) | |

-> digit

->

->

-> | / | $

-> + | - | $

-> | $

->

-> = | $

-> | { }

->

-> , | $

-> , | $

->

-> | $

-> ;

-> | | | | $

->

-> = ; | ( ) ;

->

-> , | $

-> | |

-> string

-> for ( ; ) { }

->

-> | == | !=

->

-> ++ | --

-> if ( ) { }

-> else { } | $

-> return ;

词法分析头文件：

LexAnalysis.h

//LexAnalysis.h

#ifndef _LEXANALYSIS_H

#define _LEXANALYSIS_H

//keyword

#define AUTO 1

#define BREAK 2

#define CASE 3

#define CHAR 4

#define CONST 5

#define CONTINUE 6

#define DEFAULT 7

#define DO 8

#define DOUBLE 9

#define ELSE 10

#define ENUM 11

#define EXTERN 12

#define FLOAT 13

#define FOR 14

#define GOTO 15

#define IF 16

#define INT 17

#define LONG 18

#define REGISTER 19

#define RETURN 20

#define SHORT 21

#define SIGNED 22

#define SIZEOF 23

#define STATIC 24

#define STRUCT 25

#define SWITCH 26

#define TYPEDEF 27

#define UNION 28

#define UNSIGNED 29

#define VOID 30

#define VOLATILE 31

#define WHILE 32

#define KEY_DESC "keyword"

//标志符

#define IDENTIFER 40

#define IDENTIFER_DESC "标志符"

//常量

#define INT_VAL 51 //整形常量

#define CHAR_VAL 52 //字符常量

#define FLOAT_VAL 53 //浮点数常量

#define STRING_VAL 54 //双精度浮点数常量

#define MACRO_VAL 55 //宏常量

#define CONSTANT_DESC "常量"

//运算符

#define //代码效果参考：http://hnjlyzjd.com/xl/wz_24225.html

NOT 61 // !

#define BYTE_AND 62 //&

#define COMPLEMENT 63 // ~

#define BYTE_XOR 64 // ^

#define MUL 65 //

#define DIV 66// /

#define MOD 67 // %

#define ADD 68 // +

#define SUB 69 // -

#define LES_THAN 70 //

#define ASG 72 // =

#define ARROW 73 // ->

#define SELF_ADD 74 // ++

#define SELF_SUB 75 // --

#define LEFT_MOVE 76 // [

#define RIGHT_MOVE 77 // ]

#define LES_EQUAL 78 // =

#define EQUAL 80 // ==

#define NOT_EQUAL 81 // !=

#define AND 82 // &&

#define OR 83 // ||

#define COMPLETE_ADD 84 // +=

#define COMPLETE_SUB 85 // -=

#define COMPLETE_MUL 86 // =

#define COMPLETE_DIV 87 // /=

#define COMPLETE_BYTE_XOR 88 ////代码效果参考：http://hnjlyzjd.com/hw/wz_24223.html

^=

#define COMPLETE_BYTE_AND 89 // &=

#define COMPLETE_COMPLEMENT 90 // ~=

#define COMPLETE_MOD 91 //%=

#define BYTE_OR 92 // |

#define OPE_DESC "运算符"

//限界符

#define LEFT_BRA 100 // (

#define RIGHT_BRA 101 // )

#define LEFT_INDEX 102 // 【

#define RIGHT_INDEX 103 // 】

#define L_BOUNDER 104 // {

#define R_BOUNDER 105 // }

#define POINTER 106 // .

#define JING 107 // #

#define UNDERLINE 108 //

#define COMMA 109 // ,

#define SEMI 110 // ;

#define SIN_QUE 111 // '

#define DOU_QUE 112 // "

#define CLE_OPE_DESC "限界符"

#define NOTE1 120 // "//"凝视

#define NOTE2 121 // "//"凝视

#define NOTE_DESC "凝视"

#define HEADER 130 //头文件

#define HEADER_DESC "头文件"

//错误类型

#define FLOAT_ERROR "float表示错误"

#define FLOAT_ERROR_NUM 1

#define DOUBLE_ERROR "double表示错误"

#define DOUBLE_ERROR_NUM 2

#define NOTE_ERROR "凝视没有结束符"

#define NOTE_ERROR_NUM 3

#define STRING_ERROR "字符串常量没有结束符"

#define STRING_ERROR_NUM 4

#define CHARCONST_ERROR "字符常量没有结束符"

#define CHARCONST_ERROR_NUM 5

#define CHAR_ERROR "非法字符"

#define CHAR_ERROR_NUM 6

#define LEFT_BRA_ERROR "'('没有相应项"

#define LEFT_BRA_ERROR_NUM 7

#define RIGHT_BRA_ERROR "')'没有相应项"

#define RIGHT_BRA_ERROR_NUM 8

#define LEFT_INDEX_ERROR "'【'没有相应项"

#define LEFT_INDEX_ERROR_NUM 9

#define RIGHT_INDEX_ERROR "'】'没有相应项"

#define RIGHT_INDEX_ERROR_NUM 10

#define L_BOUNDER_ERROR "'{'没有相应项"

#define L_BOUNDER_ERROR_NUM 11

#define R_BOUNDER_ERROR "'}'没有相应项"

#define R_BOUNDER_ERROR_NUM 12

#define PRE_PROCESS_ERROR "预处理错误" //头文件或者宏定义错误

#define PRE_PROCESS_ERROR_NUM 13

#define _NULL "无"

#define DESCRIBE 4000

#define TYPE 4001

#define STRING 4002

#define DIGIT 4003

struct NormalNode

{

char content【30】;//内容

char describe【30】;//描写叙述

int type;//种别码

int addr;//入口地址

int line;//所在行数

NormalNode next;//下一个节点

};

void initKeyMapping();

void initOperMapping();

void initLimitMapping();

void initNode();

void createNewNode(char content,char descirbe,int type,int addr,int line);

void createNewError(char content,char descirbe,int type,int line);

int createNewIden(char content,char descirbe,int type,int addr,int line);

void printNodeLink();

void printErrorLink();

void printIdentLink();

int mystrlen(char word);

void preProcess(char word,int line);

void close();

int seekKey(char word);

void scanner();

void BraMappingError();

#endif

语法分析头文件：

SynAnalysis.h

//SynAnalysis.h

#ifndef _SYNANALYSIS_H

#define _SYNANALYSIS_H

#define GRAMMAR_ARROW 2000 //->

#define GRAMMAR_OR 2001 // |

#define GRAMMAR_NULL 2002 //空值

#define GRAMMAR_SPECIAL 2003 //特殊符号#

#define GRAMMAR_BASE 2010 //动态生成的基值

#define Stack_Size 5000

typedef struct

{

int elem【Stack_Size】;

int top;

} SeqStack;

void initGrammer();

int seekCodeNum(char word);

void ceshi();

void First();

void Follow();

void Select();

void MTable();

void Analysis();

#endif

词法分析Cpp文件：(与先前写过的一片博客相类似，改了部分)

LexAnalysis.cpp

//LexAnalysis.cpp

#include

#include

#include

#include

#include

#include

#include

#include "LexAnalysis.h"

using namespace std;

int leftSmall = 0;//左小括号

int rightSmall = 0;//右小括号

int leftMiddle = 0;//左中括号

int rightMiddle = 0;//右中括号

int leftBig = 0;//左大括号

int rightBig = 0;//右大括号

int lineBra【6】【1000】 = {0};//括号和行数的相应关系，第一维代表左右6种括号

int static_iden_number = 0;//模拟标志符的地址，自增

//Token节点

NormalNode normalHead;//首结点

//错误节点

struct ErrorNode

{

char content【30】;//错误内容

char describe【30】;//错误描写叙述

int type;

int line;//所在行数

ErrorNode next;//下一个节点

};

ErrorNode errorHead;//首节点

//标志符节点

struct IdentiferNode

{

char content【30】;//内容

char describe【30】;//描写叙述

int type;//种别码

int addr;//入口地址

int line;//所在行数

IdentiferNode next;//下一个节点

};

IdentiferNode idenHead;//首节点

vector

keyMap;

vector

operMap;

vector

limitMap;

//初始化C语言的keyword的集合

void initKeyMapping()

{

keyMap.clear();

keyMap.push_back(make_pair("auto",AUTO));

keyMap.push_back(make_pair("break",BREAK));

keyMap.push_back(make_pair("case",CASE));

keyMap.push_back(make_pair("char",CHAR));

keyMap.push_back(make_pair("const",CONST));

keyMap.push_back(make_pair("continue",CONTINUE));

keyMap.push_back(make_pair("default",DEFAULT));

keyMap.push_back(make_pair("do",DO));

keyMap.push_back(make_pair("double",DOUBLE));

keyMap.push_back(make_pair("else",ELSE));

keyMap.push_back(make_pair("enum",ENUM));

keyMap.push_back(make_pair("extern",EXTERN));

keyMap.push_back(make_pair("float",FLOAT));

keyMap.push_back(make_pair("for",FOR));

keyMap.push_back(make_pair("goto",GOTO));

keyMap.push_back(make_pair("if",IF));

keyMap.push_back(make_pair("int",INT));

keyMap.push_back(make_pair("long",LONG));

keyMap.push_back(make_pair("register",REGISTER));

keyMap.push_back(make_pair("return",RETURN));

keyMap.push_back(make_pair("short",SHORT));

keyMap.push_back(make_pair("signed",SIGNED));

keyMap.push_back(make_pair("sizeof",SIZEOF));

keyMap.push_back(make_pair("static",STATIC));

keyMap.push_back(make_pair("struct",STRUCT));

keyMap.push_back(make_pair("switch",SWITCH));

keyMap.push_back(make_pair("typedef",TYPEDEF));

keyMap.push_back(make_pair("union",UNION));

keyMap.push_back(make_pair("unsigned",UNSIGNED));

keyMap.push_back(make_pair("void",VOID));

keyMap.push_back(make_pair("volatile",VOLATILE));

keyMap.push_back(make_pair("while",WHILE));

keyMap.push_back(make_pair("describe",DESCRIBE));

keyMap.push_back(make_pair("type",TYPE));

keyMap.push_back(make_pair("string",STRING));

keyMap.push_back(make_pair("digit",DIGIT));

}

void initOperMapping()

{

operMap.clear();

operMap.push_back(make_pair("!",NOT));

operMap.push_back(make_pair("&",BYTE_AND));

operMap.push_back(make_pair("~",COMPLEMENT));

operMap.push_back(make_pair("^",BYTE_XOR));

operMap.push_back(make_pair("",MUL));

operMap.push_back(make_pair("/",DIV));

operMap.push_back(make_pair("%",MOD));

operMap.push_back(make_pair("+",ADD));

operMap.push_back(make_pair("-",SUB));

operMap.push_back(make_pair("",GRT_THAN));

operMap.push_back(make_pair("=",ASG));

operMap.push_back(make_pair("->",ARROW));

operMap.push_back(make_pair("++",SELF_ADD));

operMap.push_back(make_pair("--",SELF_SUB));

operMap.push_back(make_pair("[",LEFT_MOVE));

operMap.push_back(make_pair("]",RIGHT_MOVE));

operMap.push_back(make_pair("=",GRT_EQUAL));

operMap.push_back(make_pair("==",EQUAL));

operMap.push_back(make_pair("!=",NOT_EQUAL));

operMap.push_back(make_pair("&&",AND));

operMap.push_back(make_pair("||",OR));

operMap.push_back(make_pair("+=",COMPLETE_ADD));

operMap.push_back(make_pair("-=",COMPLETE_SUB));

operMap.push_back(make_pair("=",COMPLETE_MUL));

operMap.push_back(make_pair("/=",COMPLETE_DIV));

operMap.push_back(make_pair("^=",COMPLETE_BYTE_XOR));

operMap.push_back(make_pair("&=",COMPLETE_BYTE_AND));

operMap.push_back(make_pair("~=",COMPLETE_COMPLEMENT));

operMap.push_back(make_pair("%=",COMPLETE_MOD));

operMap.push_back(make_pair("|",BYTE_OR));

}

void initLimitMapping()

{

limitMap.clear();

limitMap.push_back(make_pair("(",LEFT_BRA));

limitMap.push_back(make_pair(")",RIGHT_BRA));

limitMap.push_back(make_pair("【",LEFT_INDEX));

limitMap.push_back(make_pair("】",RIGHT_INDEX));

limitMap.push_back(make_pair("{",L_BOUNDER));

limitMap.push_back(make_pair("}",R_BOUNDER));

limitMap.push_back(make_pair(".",POINTER));

limitMap.push_back(make_pair("#",JING));

limitMap.push_back(makepair("",UNDER_LINE));

limitMap.push_back(make_pair(",",COMMA));

limitMap.push_back(make_pair(";",SEMI));

limitMap.push_back(make_pair("'",SIN_QUE));

limitMap.push_back(make_pair("\"",DOU_QUE));

}

void initNode()

{

normalHead = new NormalNode();

strcpy(normalHead->content,"");

strcpy(normalHead->describe,"");

normalHead->type = -1;

normalHead->addr = -1;

normalHead->line = -1;

normalHead->next = NULL;

errorHead = new ErrorNode();

strcpy(errorHead->content,"");

strcpy(errorHead->describe,"");

errorHead->line = -1;

errorHead->next = NULL;

idenHead = new IdentiferNode();

strcpy(idenHead->content,"");

strcpy(idenHead->describe,"");

idenHead->type = -1;

idenHead->addr = -1;

idenHead->line = -1;

idenHead->next = NULL;

}

void createNewNode(char content,char descirbe,int type,int addr,int line)

{

NormalNode p = normalHead;

NormalNode temp = new NormalNode();

while(p->next!=NULL)

{

p = p->next;

}

strcpy(temp->content,content);

strcpy(temp->describe,descirbe);

temp->type = type;

temp->addr = addr;

temp->line = line;

temp->next = NULL;

p->next = temp;

}

void createNewError(char content,char descirbe,int type,int line)

{

ErrorNode p = errorHead;

ErrorNode temp = new ErrorNode();

strcpy(temp->content,content);

strcpy(temp->describe,descirbe);

temp->type = type;

temp->line = line;

temp->next = NULL;

while(p->next!=NULL)

{

p = p->next;

}

p->next = temp;

}

//返回值是新的标志符的入口地址

int createNewIden(char content,char descirbe,int type,int addr,int line)

{

IdentiferNode p = idenHead;

IdentiferNode temp = new IdentiferNode();

int flag = 0;

int addr_temp = -2;

while(p->next!=NULL)

{

if(strcmp(content,p->next->content) == 0)

{

flag = 1;

addr_temp = p->next->addr;

}

p = p->next;

}

if(flag == 0)

{

addr_temp = ++static_iden_number;//用自增来模拟入口地址

}

strcpy(temp->content,content);

strcpy(temp->describe,descirbe);

temp->type = type;

temp->addr = addr_temp;

temp->line = line;

temp->next = NULL;

p->next = temp;

return addr_temp;

}

void printNodeLink()

{

NormalNode p = normalHead;

p = p->next;

cout["*分析表**"[endl[endl;

cout[setw(30)["内容"[setw(10)["描写叙述"["\t"["种别码"["\t"["地址"["\t"["行号"[endl;

while(p!=NULL)

{

if(p->type == IDENTIFER)

{

cout[setw(30)[p->content[setw(10)[p->describe["\t"[p->type["\t"[p->addr["\t"[p->line[endl;

}

else

{

cout[setw(30)[p->content[setw(10)[p->describe["\t"[p->type["\t"["\t"[p->line[endl;

}

p = p->next;

}

cout[endl[endl;

}

/

错误种类：

1.float表示错误

2.double表示错误

3.凝视没有结束符

4.字符串常量没有结束符

5.字符常量没有结束符

6.非法字符

7.'('没有相应项

8.预处理错误

/

void printErrorLink()

{

ErrorNode p = errorHead;

p = p->next;

cout["**错误表**"[endl[endl;

cout[setw(10)["内容"[setw(30)["描写叙述"["\t"["类型"["\t"["行号"[endl;

while(p!=NULL)

{

cout[setw(10)[p->content[setw(30)[p->describe["\t"[p->type["\t"[p->line[endl;

p = p->next;

}

cout[endl[endl;

}

//标志符表，有反复部分。暂不考虑

void printIdentLink()

{

IdentiferNode p = idenHead;

p = p->next;

cout["**标志符表**"[endl[endl;

cout[setw(30)["内容"[setw(10)["描写叙述"["\t"["种别码"["\t"["地址"["\t"["行号"[endl;

while(p!=NULL)

{

cout[setw(30)[p->content[setw(10)[p->describe["\t"[p->type["\t"[p->addr["\t"[p->line[endl;

p = p->next;

}

cout[endl[endl;

}

int mystrlen(char word)

{

if(word == '\0')

{

return 0;

}

else

{

return 1+mystrlen(word+1);

}

}

//预处理，处理头文件和宏定义

void preProcess(char word,int line)

{

const char include_temp = "include";

const char define_temp = "define";

char p_include,p_define;

int flag = 0;

p_include = strstr(word,include_temp);

if(p_include!=NULL)

{

flag = 1;

int i;

for(i=7;;)

{

if((p_include+i) == ' ' || (p_include+i) == '\t')

{

i++;

}

else

{

break;

}

}

createNewNode(p_include+i,HEADER_DESC,HEADER,-1,line);

}

else

{

p_define = strstr(word,define_temp);

if(p_define!=NULL)

{

flag = 1;

int i;

for(i=7;;)

{

if((p_define+i) == ' ' || (p_define+i) == '\t')

{

i++;

}

else

{

break;

}

}

createNewNode(p_define+i,CONSTANT_DESC,MACRO_VAL,-1,line);

}

}

if(flag == 0)

{

createNewError(word,PRE_PROCESS_ERROR,PRE_PROCESS_ERROR_NUM,line);

}

}

void close()

{

//delete idenHead;

//delete errorHead;

//delete normalHead;

}

int seekKey(char word)

{

for(int i=0; i='A' && ch='a' && ch='A' && ch='a' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch='0' && ch')

{

createNewNode("->",OPE_DESC,ARROW,-1,line);

}

else if(ch == '-')

{

createNewNode("--",OPE_DESC,SELF_SUB,-1,line);

}

else if(ch == '=')

{

createNewNode("--",OPE_DESC,SELF_SUB,-1,line);

}

else

{

createNewNode("-",OPE_DESC,SUB,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理+开头的运算符

else if(ch == '+')

{

ch = fgetc(infile);

if(ch == '+')

{

createNewNode("++",OPE_DESC,SELF_ADD,-1,line);

}

else if(ch == '=')

{

createNewNode("+=",OPE_DESC,COMPLETE_ADD,-1,line);

}

else

{

createNewNode("+",OPE_DESC,ADD,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理开头的运算符

else if(ch == '')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("=",OPE_DESC,COMPLETE_MUL,-1,line);

}

else

{

createNewNode("",OPE_DESC,MUL,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理按^开头的运算符

else if(ch == '^')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("^=",OPE_DESC,COMPLETE_BYTE_XOR,-1,line);

}

else

{

createNewNode("^",OPE_DESC,BYTE_XOR,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理%开头的运算符

else if(ch == '%')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("%=",OPE_DESC,COMPLETE_MOD,-1,line);

}

else

{

createNewNode("%",OPE_DESC,MOD,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理&开头的运算符

else if(ch == '&')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("&=",OPE_DESC,COMPLETE_BYTE_AND,-1,line);

}

else if(ch == '&')

{

createNewNode("&&",OPE_DESC,AND,-1,line);

}

else

{

createNewNode("&",OPE_DESC,BYTE_AND,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理~开头的运算符

else if(ch == '~')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("~=",OPE_DESC,COMPLETE_COMPLEMENT,-1,line);

}

else

{

createNewNode("~",OPE_DESC,COMPLEMENT,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理!开头的运算符

else if(ch == '!')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("!=",OPE_DESC,NOT_EQUAL,-1,line);

}

else

{

createNewNode("!",OPE_DESC,NOT,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理<开头的运算符

else if(ch == '<')

{

ch = fgetc(infile);

if(ch == '<')

{

createNewNode("[",OPE_DESC,LEFT_MOVE,-1,line);

}

else if(ch == '=')

{

createNewNode("<=",OPE_DESC,LES_EQUAL,-1,line);

}

else

{

createNewNode("开头的运算符

else if(ch == '>')

{

ch = fgetc(infile);

if(ch == '>')

{

createNewNode("]",OPE_DESC,RIGHT_MOVE,-1,line);

}

else if(ch == '=')

{

createNewNode(">=",OPE_DESC,GRT_EQUAL,-1,line);

}

else

{

createNewNode(">",OPE_DESC,GRT_THAN,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

//处理|开头的运算符

else if(ch == '|')

{

ch = fgetc(infile);

if(ch == '|')

{

createNewNode("||",OPE_DESC,OR,-1,line);

}

else

{

createNewNode("|",OPE_DESC,BYTE_OR,-1,line);

fseek(infile,-1L,SEEK_CUR);

}

}

else if(ch == '=')

{

ch = fgetc(infile);

if(ch == '=')

{

createNewNode("==",OPE_DESC,EQUAL,