cf.c

实现pl0词法分析,是用C语言来实现的了

#include<stdio.h>
#include"pl0.h"
#include"string.h"
#include<math.h>
#include<stdlib.h>
#define stacksize 500

int main()
{
	printf("input pl/0 file?");
    scanf("%s",fname);                     //输入文件名
	fin=fopen(fname,"r"); 
	if(fin)
	{
		init();
	    getsym();
	}
	else
	{
		printf("can't open file! \n");
	}
	printf("\n");
	return(0);
}



//初始化
void init()
{
	int i;
	//设置单字符符号
	for(i=0;i<=255;i++)
	{
		ssym[i]=nul;
	}
	ssym['+']=plus;
	ssym['-']=minus;
    ssym['*']=times;
    ssym['/']=slash;
    ssym['(']=lparen;
	ssym[')']=rparen;
	ssym['=']=eql;
	ssym[',']=comma;
	ssym['.']=period;
	ssym['#']=neq;
	ssym[';']=semicolon;
	//设置保留字名字，按照字母顺序，便于折半查找
	strcpy(&(word[0][0]),"begin");
	strcpy(&(word[1][0]),"call");
	strcpy(&(word[2][0]),"const");
	strcpy(&(word[3][0]),"do");
	strcpy(&(word[4][0]),"end");
	strcpy(&(word[5][0]),"if");
	strcpy(&(word[6][0]),"odd");
	strcpy(&(word[7][0]),"procedure");
	strcpy(&(word[8][0]),"read");
	strcpy(&(word[9][0]),"then");
	strcpy(&(word[10][0]),"var");
	strcpy(&(word[11][0]),"while");
	strcpy(&(word[12][0]),"write");
	strcpy(&(word[13][0]),"program");
	//设置保留字符号
	wsym[0]=beginsym;
	wsym[1]=callsym;
	wsym[2]=constsym;
	wsym[3]=dosym;
	wsym[4]=endsym;
	wsym[5]=ifsym;
	wsym[6]=oddsym;
	wsym[7]=procsym;
	wsym[8]=readsym;
	wsym[9]=thensym;
	wsym[10]=varsym;
	wsym[11]=whilesym;
	wsym[12]=writesym;
	wsym[13]=progsym;
	//设置指令名称
	strcpy(&(mnemonic[lit][0]),"lit");
	strcpy(&(mnemonic[opr][0]),"opr");
	strcpy(&(mnemonic[lod][0]),"lod");
	strcpy(&(mnemonic[sto][0]),"sto");
	strcpy(&(mnemonic[cal][0]),"cal");
	strcpy(&(mnemonic[inte][0]),"inte");
	strcpy(&(mnemonic[jmp][0]),"jmp");
	strcpy(&(mnemonic[jpc][0]),"jpc");
	//设置符号集
	for(i=0;i<symnum;i++)
	{
		declbegsys[i]=false;
		statbegsys[i]=false;
		facbegsys[i]=false;
	}
	//设置声明开始符号集
	declbegsys[constsym]=true;
	declbegsys[varsym]=true;
	declbegsys[procsym]=true;
	//设置语句开始符号集
	statbegsys[beginsym]=true;
	statbegsys[callsym]=true;
    statbegsys[ifsym]=true;
	statbegsys[whilesym]=true;
	//设置因子开始符号集
	facbegsys[ident]=true;
	facbegsys[number]=true;
	facbegsys[lparen]=true;
}

void error(int n)
{
	char space[81];
	memset(space,32,81);
	space[cc-1]=0;//出错时当前符号已经读完，所以cc-1
	printf("****%s!%d\n",space,n);
	fprintf(fa1,"****%s!%d\n",space,n);
	err++;
}

int getch()
{ 
    if(cc==ll)
	{
		if(feof(fin))
		{
			printf("program incomplete");
			return -1;
		}
		ll=0;
		cc=0;
		printf("%d",cx);
		fprintf(fa1,"%d",cx);
		ch=' ';
		while(ch!=10)
		{
			if(EOF==fscanf(fin,"%c",&ch))
			{
				line[ll]=0;
				break;
			}
			printf("%c",ch);
			fprintf(fa1,"%c",ch);
			line[ll]=ch;
			ll++;
		}
		printf("\n");
		fprintf(fa1,"\n");
	}
    ch=line[cc];
	cc=cc+1;
	return(0);
}
//词法分析，获取一个符号

int getsym()
{
	int i,j,k;
	while(ch==' ')
	{
		getchdo;
	}
	if(ch>='a'&&ch<='z')
	{
		k=0;
		do
		{
			if(k<al)//al=10
			{
				k=k+1;
				a[k]=ch;
			}
			getchdo;
		}while(ch>='a'&&ch<='z'||ch>='0'&&ch<='9');
		strcpy(id,a);
		a[k]=0;
		i=0;
		j=norw-1;
		do
		{
			k=(i+j)/2;
			if(strcmp(id,word[k])<=0)
			{
				j=k-1;
			}
			if(strcmp(id,word[k])>=0)
			{
				i=k+1;
			}
		}while(i<=j);
		if(i-1>j)
		{
			sym=wsym[k];
		}
		else
		{
			sym=ident;
		}
	}
	else
	{
		if(ch>='0'&&ch<='9')
		{
			k=0;
			num=0;
			sym=number;
			do
			{
				num=10*num+ch-'0';
				k++;
				getchdo;
			}while(ch>='0'&&ch<='9');
			k--;
			if(k>nmax)
			{
				error(30);
			}
		}
		else
		{
			if(ch==':')
			{
				getchdo;
				if(ch=='=')
				{
					sym=becomes;
					getchdo;
				}
				else
				{
					sym=nul;
				}
			}
			else
			{
				if(ch=='<')
				{
					getchdo;
					if(ch=='=')
					{
						sym=leq;
						getchdo;
					}
					else
					{
						sym=lss;
					}
				}
				else
				{
					if(ch=='>')
					{
						getchdo;
						if(ch=='=')
						{
							sym=geq;
							getchdo;
						}
						else
						{
							sym=gtr;
						}
					}
					else
					{
						sym=ssym[ch];
						//getchdo;
						//richard
						if(sym!=period)
						{
							getchdo;
						}
						//end richard
					}
				}
			}
		}
	}
	return(0);
}