work.cpp

编译器

#include "PL.h"
#define stacksize 500
int main()
{
	cout<<"Please Enter So File Name?";
	cin>>fname;
	fin.open(fname);
	if(fin.is_open())
	{
		fa1.open("fa1.tmp");
		fa1<<"Input pl/0 file?"<<fname<<"\n";
		init();
		err = 0;
		cc = cx = ll = 0;
		ch = ' ';
		if(-1 != getsym())
		{
			fa.open("fa.tmp");
			if(-1==expression())
			{
				fa.close();
				fa1.close();
				fas.close();
				fin.close();
				cout<<endl;
				return 0;
			}
			listcode();
			fa.close();
			fa1.close();
			fas.close();
			if(sym != eql)
			{
				error(9);
			}
			if(err == 0)
			{
				
				fa2.open("fa2.tmp");
				interpret();
				fa2.close();
			}
			else
				cout<<"Errors in pl/0 program";
		}
	}
	return 0;
}
void init()
{
	int i;
	for(i = 0; i <= 255; i++)
	{
		ssym[i] = nul;
	}
	ssym['+']=plus;
	ssym['-']=minus;
	ssym['*']=times;
	ssym['/']=slash;
	ssym['(']=lparen;
	ssym[')']=rparen;
	ssym['=']=eql;
	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]),"int");
	strcpy(&(mnemonic[jmp][0]),"jmp");
	strcpy(&(mnemonic[jpc][0]),"jpc");
}

void error(int n)
{
	char space[81];
	memset(space,32,81);
	space[cc-1]=0;
//	printf("****%s!%d\n",space,n);
	cout<<"****"<<space<<"!"<<n<<endl;
	fa1<<"****"<<space<<"!"<<n<<endl;
	err++;
}

int getch()
{
	if(cc == ll)
	{
		if(fin.eof())
		{
			cout<<"program incomplete!\n";
			return -1;
		}
		ll=0;
		cc=0;
		cout<<cx<<' ';
		fa1<<cx<<' ';
		ch=' ';
		while(ch!=10)
		{
			//fscanf(fin,"%c",&ch))
			ch = fin.get();
			if(EOF == ch)
			{
				line[ll]=0;
				break;
			}
			cout<<ch;
			fa1<<ch;
			line[ll]=ch;
			ll++;
		}
		cout<<"\n";
		fa1<<"\n";
	}
	ch=line[cc];
	cc++;
	return 0;
}

int getsym()
{
	int k;
	while(ch==' ' || ch==10 || ch==9)
		getchdo;
	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
	{
		sym = ssym[ch];
		getchdo;
	}
	return 0;
}

int gen(enum fct x,int y,int z)
{
	if(cx >= cxmax)
	{
		cout<<"Program too long";
		return -1;
	}
	code[cx].f=x;
	code[cx].l=y;
	code[cx].a=z;
	cx++;
	return 0;
}

void listcode()
{
	for(int i=0; i<cx; i++)
	{
		cout<<i<<" "<<mnemonic[code[i].f]<<" "<<code[i].a<<endl;
		fa<<i<<" "<<mnemonic[code[i].f]<<" "<<code[i].a<<endl;
	}
}

int expression()
{

	enum symbol addop;
	
	if(sym==plus||sym==minus)
	{
		addop = sym;
		getsymdo;
		term();
		if(addop == minus)
			gendo(opr,0,1);
	}
	else
	{
		term();
	}
	
	while(sym==plus||sym==minus)
	{
		addop = sym;
		getsymdo;
		term();
		if(addop == plus)
		{
			gendo(opr,0,2);
		}
		else
		{
			gendo(opr,0,3);
		}
	}
	if(sym ==eql)
	{
		gen(opr,0,14);
	}
	return 0;
}

int term()
{
	enum symbol mulop;
	factor();
	while(sym==times || sym==slash)
	{
		mulop = sym;
		getsymdo;
		factor();
		if(mulop == times)
		{
			gendo(opr,0,4);
		}
		else
		{
			gendo(opr,0,5);
		}
	}
	return 0;
}

int factor()
{
	if(sym == number)
	{
		if(num > amax)
		{
			error(31);
			num = 0;
		}
		gen(lit,0,num);
		getsymdo;
	}
	else if(sym == lparen)
	{
		getsym();
		expression();
		if(sym == rparen)
			getsym();
		else
			error(22);
	}
	 
	
	return 0;
}

void interpret()
{
	struct instruction i;
	int s[stacksize];
	cout<<"start pl0\n";
	int t = 0;
	int p = 0;
	s[0]=s[1]=s[2]=0;
	do {
		i=code[p];
		p++;
		switch(i.f)
		{
			case lit:
				s[t] = i.a;
				t++;
				break;
			case opr:
				switch(i.a)
				{
					case 1:
						s[t-1] = -s[t-1];
						break;
					case 2:
						t--;
						s[t-1] = s[t-1] + s[t];
						break;
					case 3:
						t--;
						s[t-1] = s[t-1] - s[t];
						break;
					case 4:
						t--;
						s[t-1] = s[t-1] * s[t];
						break;
					case 5:
						t--;
						s[t-1] = s[t-1] / s[t];
						break;
					case 14:
						cout<<s[t-1]<<"\n";
						fa2<<s[t-1]<<"\n";
						t--;
						break;
				}
		}
	} while(t != 0);
}