#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#undef DEBUG

#define iofail() do { perror(pname); exit(EXIT_FAILURE); } while (0)
#define iofailn(e) do { errno=(e); perror(pname); exit(EXIT_FAILURE); } while (0)

struct sym {
	struct sym *succ;
	char *sym,*val;
	} *symt;
char *pname;

#define WHITE(c) ((c)==' '||(c)=='\t')

static char *getsym(char *s)
{
struct sym *sm=symt;
#ifdef DEBUG
	fprintf(stderr,"getsym(\"%s\")\n",s);
#endif
	while (sm) {
		if (!strcmp(sm->sym,s)) {
#ifdef DEBUG
			fputs("getsym() - OK",stderr);
#endif
			return(sm->val);
			}
		sm=sm->succ;
		}
#ifdef DEBUG
	fputs("getsym() - NOT FOUND",stderr);
#endif
	return(NULL);
}

static void addsym(char *sym,char *val)
{
size_t syml;
struct sym *sm=malloc(sizeof(*sm)+(syml=strlen(sym)+1)+strlen(val)+1);
#ifdef DEBUG
	fprintf(stderr,"addsym(\"%s\",\"%s\")\n",sym,val);
#endif
	if (!sm) iofail();
	sm->succ=symt;
	symt=sm;
	strcpy(symt->val=strcpy(symt->sym=(char *)sm+sizeof(*sm),sym)+syml,val);
#ifdef DEBUG
	fputs("addsym() end\n",stderr);
#endif
}

static char *strip(char *s)
{
char *s2;
#ifdef DEBUG
	fprintf(stderr,"strip(\"%s\")\n",s);
#endif
	while (WHITE(*s)) s++;
	for (s2=s;*s2;s2++); s2--;
	while (s2>=s&&WHITE(*s2)) s2--;
	*(s2+1)='\0';
#ifdef DEBUG
	fprintf(stderr,"strip()==\"%s\"\n",s);
#endif
	return(s);
}

static char *quote(char **sp)
{
char *s=*sp,*s2;
	while (WHITE(*s)) s++;
	if (*s++!='"') return(NULL);
	s2=s;
	while (*s&&*s!='"') s++;
	if (!*s) return(NULL);
	*s++='\0'; *sp=s;
	return(s2);
}

int eval(char *s,char *buf,int bs)
{
#ifdef DEBUG
	fprintf(stderr,"eval(\"%s\")\n",s);
#endif
	for (;;) {
		while (*s&&*s!='$'&&bs) bs--,*buf++=*s++;
		if (!bs) return(0);
		if (!*s) {
			*buf++='\0';
#ifdef DEBUG
			fputs("eval() end\n",stderr);
#endif
			return(1);
			}
		if (*++s=='(') {
char *smn=++s,*sym;
			while (*s&&*s!=')') s++;
			if (!*s) return(0);
			*s++='\0';
			if ((sym=getsym(smn))) {
				while (*sym&&bs) bs--,*buf++=*sym++;
				if (!bs) return(0);
				}
			}
		else *buf++='$';
		}
}

int main(int argc,char **argv)
{
char line[512],outt[sizeof(line)],*s;
char *c1,*c2,cn1[512],cn2[sizeof(cn1)];
int lins,run=1,cdpos,proc,i;
	if ((pname=rindex(*argv,'/'))) pname++;
	else pname=*argv;
	puts("\
##############################################################\n\
### This file was created automatically by gmk2mk utility. ###\n\
### PLEASE DON'T EDIT THIS FILE, edit GNUmakefile instead. ###\n\
##############################################################\n");
	while (fgets(line,sizeof(line),stdin)) {
		if (line[(lins=strlen(line))-1]=='\n') line[--lins]='\0';
		strcpy(outt,line);
		cdpos=1;
		for (i=0;i<lins;i++)
			if (line[i]=='"') cdpos=!cdpos;
			else if (cdpos&&line[i]=='#') {
				line[lins=i]='\0';
				break;
				}
		proc=1;
		if (!strncmp(line,"ifeq ",5)) {
			cdpos=5;
valcond:
			proc=0; s=&line[cdpos];
			if ((c1=quote(&s))) if ((c2=quote(&s))) {
				while (WHITE(*s)) s++;
				if (!*s&&eval(c1,cn1,sizeof(cn1))&&eval(c2,cn2,sizeof(cn2))) {
					i=strcmp(cn1,cn2);
					run=(!i&&cdpos==5)||(!!i&&cdpos==6);
					}
				}
			}
		else if (!strncmp(line,"ifneq ",6)) {
			cdpos=6;
			goto valcond;
			}
		else if (!strncmp(line,"ifdef ",6)) {
			run=!!getsym(strip(&line[6]));
			proc=0;
			}
		else if (!strncmp(line,"ifndef ",7)) {
			run=!getsym(strip(&line[7]));
			proc=0;
			}
		else if (!strncmp(line,"else",4)) {
			run=!run;
			proc=0;
			}
		else if (!strncmp(line,"endif",5)) {
			run=1;
			proc=0;
			}
		if (!run||!proc) putchar('#');
		else {
			for (i=0;i<lins;i++)
				if (line[i]=='=') {
					line[i++]='\0';
					if (eval(strip(&line[i]),cn1,sizeof(cn1))) {
						addsym(strip(line),cn1);
						}
					break;
					}
			}
		puts(outt);
		}
	return(EXIT_SUCCESS);
}