macro.c

lcc,一个可变目标c语言编译器的源码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "cpp.h"

/*
 * do a macro definition.  tp points to the name being defined in the line
 */
void
dodefine(Tokenrow *trp)
{
	Token *tp;
	Nlist *np;
	Tokenrow *def, *args;

	tp = trp->tp+1;
	if (tp>=trp->lp || tp->type!=NAME) {
		error(ERROR, "#defined token is not a name");
		return;
	}
	np = lookup(tp, 1);
	if (np->flag&ISUNCHANGE) {
		error(ERROR, "#defined token %t can't be redefined", tp);
		return;
	}
	/* collect arguments */
	tp += 1;
	args = NULL;
	if (tp<trp->lp && tp->type==LP && tp->wslen==0) {
		/* macro with args */
		int narg = 0;
		tp += 1;
		args = new(Tokenrow);
		maketokenrow(2, args);
		if (tp->type!=RP) {
			int err = 0;
			for (;;) {
				Token *atp;
				if (tp->type!=NAME) {
					err++;
					break;
				}
				if (narg>=args->max)
					growtokenrow(args);
				for (atp=args->bp; atp<args->lp; atp++)
					if (atp->len==tp->len
					 && strncmp((char*)atp->t, (char*)tp->t, tp->len)==0)
						error(ERROR, "Duplicate macro argument");
				*args->lp++ = *tp;
				narg++;
				tp += 1;
				if (tp->type==RP)
					break;
				if (tp->type!=COMMA) {
					err++;
					break;
				}
				tp += 1;
			}
			if (err) {
				error(ERROR, "Syntax error in macro parameters");
				return;
			}
		}
		tp += 1;
	}
	trp->tp = tp;
	if (((trp->lp)-1)->type==NL)
		trp->lp -= 1;
	def = normtokenrow(trp);
	if (np->flag&ISDEFINED) {
		if (comparetokens(def, np->vp)
		 || (np->ap==NULL) != (args==NULL)
		 || np->ap && comparetokens(args, np->ap))
			error(ERROR, "Macro redefinition of %t", trp->bp+2);
	}
	if (args) {
		Tokenrow *tap;
		tap = normtokenrow(args);
		dofree(args->bp);
		args = tap;
	}
	np->ap = args;
	np->vp = def;
	np->flag |= ISDEFINED;
}

/*
 * Definition received via -D or -U
 */
void
doadefine(Tokenrow *trp, int type)
{
	Nlist *np;
	static unsigned char one[] = "1";
	static Token onetoken[1] = {{ NUMBER, 0, 0, 0, 1, one }};
	static Tokenrow onetr = { onetoken, onetoken, onetoken+1, 1 };

	trp->tp = trp->bp;
	if (type=='U') {
		if (trp->lp-trp->tp != 2 || trp->tp->type!=NAME)
			goto syntax;
		if ((np = lookup(trp->tp, 0)) == NULL)
			return;
		np->flag &= ~ISDEFINED;
		return;
	}
	if (trp->tp >= trp->lp || trp->tp->type!=NAME)
		goto syntax;
	np = lookup(trp->tp, 1);
	np->flag |= ISDEFINED;
	trp->tp += 1;
	if (trp->tp >= trp->lp || trp->tp->type==END) {
		np->vp = &onetr;
		return;
	}
	if (trp->tp->type!=ASGN)
		goto syntax;
	trp->tp += 1;
	if ((trp->lp-1)->type == END)
		trp->lp -= 1;
	np->vp = normtokenrow(trp);
	return;
syntax:
	error(FATAL, "Illegal -D or -U argument %r", trp);
}
			
/*
 * Do macro expansion in a row of tokens.
 * Flag is NULL if more input can be gathered.
 */
void
expandrow(Tokenrow *trp, char *flag)
{
	Token *tp;
	Nlist *np;

	if (flag)
		setsource(flag, NULL, "");
	for (tp = trp->tp; tp<trp->lp; ) {
		if (tp->type!=NAME
		 || quicklook(tp->t[0], tp->len>1?tp->t[1]:0)==0
		 || (np = lookup(tp, 0))==NULL
		 || (np->flag&(ISDEFINED|ISMAC))==0
		 || tp->hideset && checkhideset(tp->hideset, np)) {
			tp++;
			continue;
		}
		trp->tp = tp;
		if (np->val==KDEFINED) {
			tp->type = DEFINED;
			if ((tp+1)<trp->lp && (tp+1)->type==NAME)
				(tp+1)->type = NAME1;
			else if ((tp+3)<trp->lp && (tp+1)->type==LP
			 && (tp+2)->type==NAME && (tp+3)->type==RP)
				(tp+2)->type = NAME1;
			else
				error(ERROR, "Incorrect syntax for `defined'");
			tp++;
			continue;
		}
		if (np->flag&ISMAC)
			builtin(trp, np->val);
		else {
			expand(trp, np);
		}
		tp = trp->tp;
	}
	if (flag)
		unsetsource();
}

/*
 * Expand the macro whose name is np, at token trp->tp, in the tokenrow.
 * Return trp->tp at the first token next to be expanded
 * (ordinarily the beginning of the expansion)
 */
void
expand(Tokenrow *trp, Nlist *np)
{
	Tokenrow ntr;
	int ntokc, narg, i;
	Token *tp;
	Tokenrow *atr[NARG+1];
	int hs;

	copytokenrow(&ntr, np->vp);		/* copy macro value */
	if (np->ap==NULL)			/* parameterless */
		ntokc = 1;
	else {
		ntokc = gatherargs(trp, atr, &narg);
		if (narg<0) {			/* not actually a call (no '(') */
			/* gatherargs has already pushed trp->tr to the next token */
			return;
		}
		if (narg != rowlen(np->ap)) {
			error(ERROR, "Disagreement in number of macro arguments");
			trp->tp->hideset = newhideset(trp->tp->hideset, np);
			trp->tp += ntokc;
			return;
		}
		substargs(np, &ntr, atr);	/* put args into replacement */
		for (i=0; i<narg; i++) {
			dofree(atr[i]->bp);
			dofree(atr[i]);
		}
	}
	doconcat(&ntr);				/* execute ## operators */
	hs = newhideset(trp->tp->hideset, np);
	for (tp=ntr.bp; tp<ntr.lp; tp++) {	/* distribute hidesets */
		if (tp->type==NAME) {
			if (tp->hideset==0)
				tp->hideset = hs;
			else
				tp->hideset = unionhideset(tp->hideset, hs);
		}
	}
	ntr.tp = ntr.bp;
	insertrow(trp, ntokc, &ntr);
	trp->tp -= rowlen(&ntr);
	dofree(ntr.bp);
	return;
}	

/*
 * Gather an arglist, starting in trp with tp pointing at the macro name.
 * Return total number of tokens passed, stash number of args found.
 * trp->tp is not changed relative to the tokenrow.
 */
int
gatherargs(Tokenrow *trp, Tokenrow **atr, int *narg)
{
	int parens = 1;
	int ntok = 0;
	Token *bp, *lp;
	Tokenrow ttr;
	int ntokp;
	int needspace;

	*narg = -1;			/* means that there is no macro call */
	/* look for the ( */
	for (;;) {
		trp->tp++;
		ntok++;
		if (trp->tp >= trp->lp) {
			gettokens(trp, 0);
			if ((trp->lp-1)->type==END) {
				trp->lp -= 1;
				trp->tp -= ntok;
				return ntok;
			}
		}
		if (trp->tp->type==LP)
			break;
		if (trp->tp->type!=NL)
			return ntok;
	}
	*narg = 0;
	ntok++;
	ntokp = ntok;
	trp->tp++;
	/* search for the terminating ), possibly extending the row */
	needspace = 0;
	while (parens>0) {
		if (trp->tp >= trp->lp)
			gettokens(trp, 0);
		if (needspace) {
			needspace = 0;
			makespace(trp);
		}
		if (trp->tp->type==END) {
			trp->lp -= 1;
			trp->tp -= ntok;
			error(ERROR, "EOF in macro arglist");
			return ntok;
		}
		if (trp->tp->type==NL) {
			trp->tp += 1;
			adjustrow(trp, -1);
			trp->tp -= 1;
			makespace(trp);
			needspace = 1;
			continue;
		}
		if (trp->tp->type==LP)
			parens++;
		else if (trp->tp->type==RP)
			parens--;
		trp->tp++;
		ntok++;
	}
	trp->tp -= ntok;
	/* Now trp->tp won't move underneath us */
	lp = bp = trp->tp+ntokp;
	for (; parens>=0; lp++) {
		if (lp->type == LP) {
			parens++;
			continue;
		}
		if (lp->type==RP)
			parens--;
		if (lp->type==DSHARP)
			lp->type = DSHARP1;	/* ## not special in arg */
		if (lp->type==COMMA && parens==0 || parens<0 && (lp-1)->type!=LP) {
			if (*narg>=NARG-1)
				error(FATAL, "Sorry, too many macro arguments");
			ttr.bp = ttr.tp = bp;
			ttr.lp = lp;
			atr[(*narg)++] = normtokenrow(&ttr);
			bp = lp+1;
		}
	}
	return ntok;
}

/*
 * substitute the argument list into the replacement string
 *  This would be simple except for ## and #
 */
void
substargs(Nlist *np, Tokenrow *rtr, Tokenrow **atr)
{
	Tokenrow tatr;
	Token *tp;
	int ntok, argno;

	for (rtr->tp=rtr->bp; rtr->tp<rtr->lp; ) {
		if (rtr->tp->type==SHARP) {	/* string operator */
			tp = rtr->tp;
			rtr->tp += 1;
			if ((argno = lookuparg(np, rtr->tp))<0) {
				error(ERROR, "# not followed by macro parameter");
				continue;
			}
			ntok = 1 + (rtr->tp - tp);
			rtr->tp = tp;
			insertrow(rtr, ntok, stringify(atr[argno]));
			continue;
		}
		if (rtr->tp->type==NAME
		 && (argno = lookuparg(np, rtr->tp)) >= 0) {
			if ((rtr->tp+1)->type==DSHARP
			 || rtr->tp!=rtr->bp && (rtr->tp-1)->type==DSHARP)
				insertrow(rtr, 1, atr[argno]);
			else {
				copytokenrow(&tatr, atr[argno]);
				expandrow(&tatr, "<macro>");
				insertrow(rtr, 1, &tatr);
				dofree(tatr.bp);
			}
			continue;
		}
		rtr->tp++;
	}
}

/*
 * Evaluate the ## operators in a tokenrow
 */
void
doconcat(Tokenrow *trp)
{
	Token *ltp, *ntp;
	Tokenrow ntr;
	int len;

	for (trp->tp=trp->bp; trp->tp<trp->lp; trp->tp++) {
		if (trp->tp->type==DSHARP1)
			trp->tp->type = DSHARP;
		else if (trp->tp->type==DSHARP) {
			char tt[128];
			ltp = trp->tp-1;
			ntp = trp->tp+1;
			if (ltp<trp->bp || ntp>=trp->lp) {
				error(ERROR, "## occurs at border of replacement");
				continue;
			}
			len = ltp->len + ntp->len;
			strncpy((char*)tt, (char*)ltp->t, ltp->len);
			strncpy((char*)tt+ltp->len, (char*)ntp->t, ntp->len);
			tt[len] = '\0';
			setsource("<##>", NULL, tt);
			maketokenrow(3, &ntr);
			gettokens(&ntr, 1);
			unsetsource();
			if (ntr.lp-ntr.bp!=2 || ntr.bp->type==UNCLASS)
				error(WARNING, "Bad token %r produced by ##", &ntr);
			ntr.lp = ntr.bp+1;
			trp->tp = ltp;
			makespace(&ntr);
			insertrow(trp, (ntp-ltp)+1, &ntr);
			dofree(ntr.bp);
			trp->tp--;
		}
	}
}

/*
 * tp is a potential parameter name of macro mac;
 * look it up in mac's arglist, and if found, return the
 * corresponding index in the argname array.  Return -1 if not found.
 */
int
lookuparg(Nlist *mac, Token *tp)
{
	Token *ap;

	if (tp->type!=NAME || mac->ap==NULL)
		return -1;
	for (ap=mac->ap->bp; ap<mac->ap->lp; ap++) {
		if (ap->len==tp->len && strncmp((char*)ap->t,(char*)tp->t,ap->len)==0)
			return ap - mac->ap->bp;
	}
	return -1;
}

/*
 * Return a quoted version of the tokenrow (from # arg)
 */
#define	STRLEN	512
Tokenrow *
stringify(Tokenrow *vp)
{
	static Token t = { STRING };
	static Tokenrow tr = { &t, &t, &t+1, 1 };
	Token *tp;
	uchar s[STRLEN];
	uchar *sp = s, *cp;
	int i, instring;

	*sp++ = '"';
	for (tp = vp->bp; tp < vp->lp; tp++) {
		instring = tp->type==STRING || tp->type==CCON;
		if (sp+2*tp->len >= &s[STRLEN-10]) {
			error(ERROR, "Stringified macro arg is too long");
			break;
		}
		if (tp->wslen && (tp->flag&XPWS)==0)
			*sp++ = ' ';
		for (i=0, cp=tp->t; i<tp->len; i++) {	
			if (instring && (*cp=='"' || *cp=='\\'))
				*sp++ = '\\';
			*sp++ = *cp++;
		}
	}
	*sp++ = '"';
	*sp = '\0';
	sp = s;
	t.len = strlen((char*)sp);
	t.t = newstring(sp, t.len, 0);
	return &tr;
}

/*
 * expand a builtin name
 */
void
builtin(Tokenrow *trp, int biname)
{
	char *op;
	Token *tp;
	Source *s;

	tp = trp->tp;
	trp->tp++;
	/* need to find the real source */
	s = cursource;
	while (s && s->fd==NULL)
		s = s->next;
	if (s==NULL)
		s = cursource;
	/* most are strings */
	tp->type = STRING;
	if (tp->wslen) {
		*outp++ = ' ';
		tp->wslen = 1;
	}
	op = outp;
	*op++ = '"';
	switch (biname) {

	case KLINENO:
		tp->type = NUMBER;
		op = outnum(op-1, s->line);
		break;

	case KFILE: {
		char *src = s->filename;
		while ((*op++ = *src++) != 0)
			if (src[-1] == '\\')
				*op++ = '\\';
		op--;
		break;
		}

	case KDATE:
		strncpy(op, curtime+4, 7);
		strncpy(op+7, curtime+20, 4);
		op += 11;
		break;

	case KTIME:
		strncpy(op, curtime+11, 8);
		op += 8;
		break;

	default:
		error(ERROR, "cpp botch: unknown internal macro");
		return;
	}
	if (tp->type==STRING)
		*op++ = '"';
	tp->t = (uchar*)outp;
	tp->len = op - outp;
	outp = op;
}