set.c

pl0编译器,c语言环境下实现,PL/0语言编译程序采用以语法分析为核心、一遍扫描的编译方法。词法分析和代码生成作为独立的子程序供语法分析程序调用。程序供语法分析程序调用。

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include "set.h"

symset uniteset(symset s1, symset s2)
{
	symset s;
	snode* p;
	
	s = p = (snode*) malloc(sizeof(snode));
	
// added by yzhang 02-02-28
	s1 = s1->next; s2 = s2->next; 
// end add
	
	while (s1 && s2)
	{
		p->next = (snode*) malloc(sizeof(snode));
		p = p->next;
		if (s1->elem < s2->elem)
		{
			p->elem = s1->elem;
			s1 = s1->next;
		}
		else
		{
			p->elem = s2->elem;
			s2 = s2->next;
		}
	}
	
	if ( s2 )	s1 = s2;	//added by yzhang 02-02-28

	while (s1)
	{
		p->next = (snode*) malloc(sizeof(snode));
		p = p->next;
		p->elem = s1->elem;
		s1 = s1->next;
		
	}
/* deleted by yzhang	02-02-28
	while (s2)
	{
		p->next = (snode*) malloc(sizeof(snode));
		p = p->next;
		p->elem = s2->elem;
		s2 = s2->next;
	}
*/
	p->next = NULL;

	return s;
} // uniteset

void setinsert(symset s, int elem)
{
	snode* p = s;
	snode* q;

	while (p->next && p->next->elem < elem)
	{
		p = p->next;
	}
	
	q = (snode*) malloc(sizeof(snode));
	q->elem = elem;
	q->next = p->next;
	p->next = q;
} // setinsert

symset createset(int elem, .../* SYM_NULL */)
{
	va_list list;
	symset s;

	s = (snode*) malloc(sizeof(snode));
	s->next = NULL;

	va_start(list, elem);
	while (elem)
	{
		setinsert(s, elem);
		elem = va_arg(list, int);
	}
	va_end(list);
	return s;
} // createset

void destroyset(symset s)
{
	snode* p;

	while (s)
	{
		p = s;
		s = s->next;
		free(p);
	}
} // destroyset

int inset(int elem, symset s)
{
	s = s->next;
	while (s && s->elem < elem)
		s = s->next;

	if (s && s->elem == elem)
		return 1;
	else
		return 0;
} // inset

//added by yzhang 02-02-28
void showset(symset s)
{
	s = s->next;
	while (s ){
		printf("%d,", s->elem);
		s = s->next;
	}
	printf("\n");
} // showset


// EOF set.c