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/*
 *	Macro control for make
 */

#include "h.h"

MACROP		macrohead;

MACROP
getmp(name)
char *			name;
{
	register MACROP	rp;

	for (rp = macrohead; rp; rp = rp->m_next)
		if (strcmp(name, rp->m_name) == 0)
			return rp;
	return NULL_MACROP;
}


char *
getmacro(name)
char *			name;
{
	MACROP		mp;

	if (mp = getmp(name))
		return mp->m_val;
	else
		return "";
}


MACROP
setmacro(name, val)
char *			name;
char *			val;
{
	register MACROP	rp;
	register char *		cp;


			/*  Replace macro definition if it exists  */
	for (rp = macrohead; rp; rp = rp->m_next)
		if (strcmp(name, rp->m_name) == 0)
		{
			free((char *)(rp->m_val));	/*  Free space from old  */
			break;
		}

	if (!rp)		/*  If not defined, allocate space for new  */
	{
		if ((rp = (MACROP)malloc(sizeof (MACRO))) == NULL_MACROP)
			fatal("No memory for macro");

		rp->m_next = macrohead;
		macrohead = rp;
		rp->m_flag = FALSE;

		if ((cp = malloc(strlen(name)+1)) == NULL_CHARP)
			fatal("No memory for macro");
		strcpy(cp, name);
		rp->m_name = cp;
	}

	if ((cp = malloc(strlen(val)+1)) == NULL_CHARP)
		fatal("No memory for macro");
	strcpy(cp, val);		/*  Copy in new value  */
	rp->m_val = cp;

	return rp;
}


/*
 *	Do the dirty work for expand
 */
void
doexp(to, from, len, buf)
char **			to;
char *			from;
int *			len;
char *			buf;
{
	register char *		rp;
	register char *		p;
	register char *		q;
	register MACROP	mp;


	rp = from;
	p = *to;
	while (*rp)
	{
		if ((*rp == '\\') && (*(rp+1) == 'n'))
		{	/* translate \n literal pair to single newline */
			*p++ = '\n';
			rp += 2;
			(*len)--;(*len)--;
		}
		else if (*rp != '$')
		{
			*p++ = *rp++;
			(*len)--;
		}
		else
		{
			q = buf;
			if (*++rp == '{')
				while (*++rp && *rp != '}')
					*q++ = *rp;
			else if (*rp == '(')
				while (*++rp && *rp != ')')
					*q++ = *rp;
			else if (!*rp)
			{
				*p++ = '$';
				break;
			}
			else
				*q++ = *rp;
			*q = '\0';
			if (*rp)
				rp++;
			if (!(mp = getmp(buf)))
				mp = setmacro(buf, "");
			if (mp->m_flag)
				fatal("Infinitely recursive macro %s", mp->m_name);
			mp->m_flag = TRUE;
			*to = p;
			doexp(to, mp->m_val, len, buf);
			p = *to;
			mp->m_flag = FALSE;
		}
		if (*len <= 0)
			error("Expanded line too line");
	}
	*p = '\0';
	*to = p;
}


/*
 *	Expand any macros in str.
 */
void
expand(str)
char *		str;
{
	static char		a[LZ];
	static char		b[LZ];
	char *			p = str;
	int			len = LZ-1;

	strcpy(a, str);
	doexp(&p, a, &len, b);
}