old.cpp

为了实现的编译程序实用

#include "stdio.h"
#include "string.h"

#define VALWORDNUM 35 //单词数
#define WORDLEN 20    //单词最大长度
#define BUFLEN 1024   //缓冲区长度

typedef struct {
	char val[5];         //种别
	char word[15];   //单词
}VAL_WORD;

//单词种别表
VAL_WORD val_word[VALWORDNUM] =
{   
	{"1",  "PROGRAM"},{"2", "CONST"},{"3",        "VAR"},{"4","INTEGER"},{"5", "LONG"},	
	{"6","PROCEDURE"},{"7",    "IF"},{"8",       "THEN"},{"9",  "WHILE"},{"10",  "DO"},	
	{"11",    "READ"},{"12","WRITE"},{"13",     "BEGIN"},{"14",   "END"},{"15", "ODD"},	
	{"16",       "+"},{"17",    "-"},{"18",         "*"},{"19",     "/"},{"20",   "="},
	{"21",      "<>"},{"22",    "<"},{"23",        "<="},{"24",     ">"},{"25",  ">="},
	{"26",       "."},{"27",    ","},{"28",         ";"},{"29",     ":"},{"30",  ":="},
	{"31",       "("},{"32",    ")"},{"33","无符号整数"},{"34","标识符"},{"35",   "#"}	 	 
};

char sourcefile[20] =  "source.pas" ;
char lexicalfile[20] = "lexical.dc" ;

void proprocess(char filename[],char buf[])//预处理
{
    FILE *fp;
	int i = 0;
	char oldchar='\0', curchar;
	bool incomment = false;
	fp = fopen(filename,"rb");
	while(!feof(fp)&&fread(&curchar,sizeof(char),1,fp)==1){
		switch(incomment){
			case false ://注释外
				if(oldchar=='/'&&curchar=='*'){//进入注释
					i--;
					incomment=true;
				}
				else {
					if(oldchar=='\\'&&curchar=='\n')i--;  //续行
					else{
						if(curchar=='\t'||curchar=='\n'||curchar==13)curchar=' ';
						if(curchar!=' '||(curchar==' '&&oldchar!=' '))buf[i++]=curchar;
					}
				}
				break;
			case true:
				if(oldchar=='*' && curchar=='/')incomment=false;//离开注释
			    break;
		}
		oldchar=curchar;
	}
	buf[i]='#';
}
void concat(char word[],char c)//拼接单词
{
	for(int i=0;word[i]!='\0';i++);
	word[i++]=c;
	word[i]='\0';
}

char* getval(char word[])//获取单词种别
{
	for(int i=0;i<VALWORDNUM;i++)
		if(strcmp(val_word[i].word,word)==0)return val_word[i].val;
	return "0";
}
void error()
{
	printf("错误!\n");
}
VAL_WORD lexical(char buf[])
{
	VAL_WORD v={"\0","\0"};
	static int i=0;
	char word[WORDLEN] = {'\0'};
	while(buf[i]==' ')i++;
    //标识符
	if((buf[i]>='A'&&buf[i]<'Z')){
		while((buf[i]>='A'&&buf[i]<'Z')||(buf[i]>='0'&&buf[i]<'9'))
			concat(word,buf[i++]);
		strcpy(v.val,getval(word));
		if(strcmp(v.val,"0")==0)strcpy(v.val,"34");
		strcpy(v.word,word);
		return v;
	}
    //无符号整数
	if(buf[i]>='0'&&buf[i]<'9'){
		while(buf[i]>='0'&&buf[i]<'9')concat(word,buf[i++]);
		strcpy(v.val,getval(word));
		if(strcmp(v.val,"0")==0)strcpy(v.val,"33");
	    strcpy(v.word,word);
		return v;
	}
	//其他
	switch(buf[i]){
		case '+':strcpy(v.word,"+");break;
		case '-':strcpy(v.word,"-");break;
		case '*':strcpy(v.word,"*");break;
		case '/':strcpy(v.word,"/");break;
		case '=':strcpy(v.word,"=");break;
		case '<':if(buf[i+1]=='>'){strcpy(v.word,"<>");i++;}
			     else if(buf[i+1]=='='){strcpy(v.word,"<=");i++;}
				 else strcpy(v.word,"<");
				 break;
		case '>':if(buf[i+1]=='='){strcpy(v.word,">=");i++;}
				 strcpy(v.word,">");
				 break;
		case '.':strcpy(v.word,".");break;
		case ',':strcpy(v.word,",");break;
		case ';':strcpy(v.word,";");break;
		case ':':if(buf[i+1]=='='){strcpy(v.word,":=");i++;}
			     strcpy(v.word,":");
				 break;
		case '(':strcpy(v.word,"(");break;
	    case ')':strcpy(v.word,")");break;
		case '#':strcpy(v.word,"#");break;
		default:strcpy(v.val,"0");
			    error();
				break;
	}
	i++;
	strcpy(v.val,getval(v.word));
	return v;
}

void main()
{
    FILE *fp;
	VAL_WORD v={0," "};
	char buf[BUFLEN]={'\0'};
	printf(">>>>>  分析正在进行中....\n\n");
	
	proprocess(sourcefile,buf);
	printf("%s\n\n",buf);
	fp = fopen(lexicalfile,"wb");
	while(strcmp(v.word,"#")!=0){
		v=lexical(buf);
		printf("%5s%15s\n",v.val,v.word);
		fwrite(&v.val,sizeof(int),1,fp);
		fwrite(&v.word,15*sizeof(char),1,fp);
	}
	fclose(fp);
	printf("\n\n>>>>>  分析成功!\n\n");
}