parser.y

unix v7是最后一个广泛发布的研究型UNIX版本

%token CHAR CCL NCCL STR DELIM SCON ITER NEWE NULLS
%left SCON '/' NEWE
%left '|'
%left '$' '^'
%left CHAR CCL NCCL '(' '.' STR NULLS
%left ITER
%left CAT
%left '*' '+' '?'

%{
# include "ldefs.c"
%}
%%
%{
int i;
int j,k;
int g;
char *p;
%}
acc	:	lexinput
	={	
# ifdef DEBUG
		if(debug) sect2dump();
# endif
	}
	;
lexinput:	defns delim prods end
	|	defns delim end
	={
		if(!funcflag)phead2();
		funcflag = TRUE;
	}
	| error
	={
# ifdef DEBUG
		if(debug) {
			sect1dump();
			sect2dump();
			}
# endif
		}
	;
end:		delim | ;
defns:	defns STR STR
	={	scopy($2,dp);
		def[dptr] = dp;
		dp =+ slength($2) + 1;
		scopy($3,dp);
		subs[dptr++] = dp;
		if(dptr >= DEFSIZE)
			error("Too many definitions");
		dp =+ slength($3) + 1;
		if(dp >= dchar+DEFCHAR)
			error("Definitions too long");
		subs[dptr]=def[dptr]=0;	/* for lookup - require ending null */
	}
	|
	;
delim:	DELIM
	={
# ifdef DEBUG
		if(sect == DEFSECTION && debug) sect1dump();
# endif
		sect++;
		}
	;
prods:	prods pr
	={	$$ = mn2(RNEWE,$1,$2);
		}
	|	pr
	={	$$ = $1;}
	;
pr:	r NEWE
	={
		if(divflg == TRUE)
			i = mn1(S1FINAL,casecount);
		else i = mn1(FINAL,casecount);
		$$ = mn2(RCAT,$1,i);
		divflg = FALSE;
		casecount++;
		}
	| error NEWE
	={
# ifdef DEBUG
		if(debug) sect2dump();
# endif
		}
r:	CHAR
	={	$$ = mn0($1); }
	| STR
	={
		p = $1;
		i = mn0(*p++);
		while(*p)
			i = mn2(RSTR,i,*p++);
		$$ = i;
		}
	| '.'
	={	symbol['\n'] = 0;
		if(psave == FALSE){
			p = ccptr;
			psave = ccptr;
			for(i=1;i<'\n';i++){
				symbol[i] = 1;
				*ccptr++ = i;
				}
			for(i='\n'+1;i<NCH;i++){
				symbol[i] = 1;
				*ccptr++ = i;
				}
			*ccptr++ = 0;
			if(ccptr > ccl+CCLSIZE)
				error("Too many large character classes");
			}
		else
			p = psave;
		$$ = mn1(RCCL,p);
		cclinter(1);
		}
	| CCL
	={	$$ = mn1(RCCL,$1); }
	| NCCL
	={	$$ = mn1(RNCCL,$1); }
	| r '*'
	={	$$ = mn1(STAR,$1); }
	| r '+'
	={	$$ = mn1(PLUS,$1); }
	| r '?'
	={	$$ = mn1(QUEST,$1); }
	| r '|' r
	={	$$ = mn2(BAR,$1,$3); }
	| r r %prec CAT
	={	$$ = mn2(RCAT,$1,$2); }
	| r '/' r
	={	if(!divflg){
			j = mn1(S2FINAL,-casecount);
			i = mn2(RCAT,$1,j);
			$$ = mn2(DIV,i,$3);
			}
		else {
			$$ = mn2(RCAT,$1,$3);
			warning("Extra slash removed");
			}
		divflg = TRUE;
		}
	| r ITER ',' ITER '}'
	={	if($2 > $4){
			i = $2;
			$2 = $4;
			$4 = i;
			}
		if($4 <= 0)
			warning("Iteration range must be positive");
		else {
			j = $1;
			for(k = 2; k<=$2;k++)
				j = mn2(RCAT,j,dupl($1));
			for(i = $2+1; i<=$4; i++){
				g = dupl($1);
				for(k=2;k<=i;k++)
					g = mn2(RCAT,g,dupl($1));
				j = mn2(BAR,j,g);
				}
			$$ = j;
			}
	}
	| r ITER '}'
	={
		if($2 < 0)warning("Can't have negative iteration");
		else if($2 == 0) $$ = mn0(RNULLS);
		else {
			j = $1;
			for(k=2;k<=$2;k++)
				j = mn2(RCAT,j,dupl($1));
			$$ = j;
			}
		}
	| r ITER ',' '}'
	={
				/* from n to infinity */
		if($2 < 0)warning("Can't have negative iteration");
		else if($2 == 0) $$ = mn1(STAR,$1);
		else if($2 == 1)$$ = mn1(PLUS,$1);
		else {		/* >= 2 iterations minimum */
			j = $1;
			for(k=2;k<$2;k++)
				j = mn2(RCAT,j,dupl($1));
			k = mn1(PLUS,dupl($1));
			$$ = mn2(RCAT,j,k);
			}
		}
	| SCON r
	={	$$ = mn2(RSCON,$2,$1); }
	| '^' r
	={	$$ = mn1(CARAT,$2); }
	| r '$'
	={	i = mn0('\n');
		if(!divflg){
			j = mn1(S2FINAL,-casecount);
			k = mn2(RCAT,$1,j);
			$$ = mn2(DIV,k,i);
			}
		else $$ = mn2(RCAT,$1,i);
		divflg = TRUE;
		}
	| '(' r ')'
	={	$$ = $2; }
	|	NULLS
	={	$$ = mn0(RNULLS); }
	;
%%
yylex(){
	register char *p;
	register int c, i;
	char  *t, *xp;
	int n, j, k, x;
	static int sectbegin;
	static char token[TOKENSIZE];
	static int iter;

# ifdef DEBUG
	yylval = 0;
# endif

	if(sect == DEFSECTION) {		/* definitions section */
		while(!eof) {
			if(prev == '\n'){		/* next char is at beginning of line */
				getl(p=buf);
				switch(*p){
				case '%':
					switch(c= *(p+1)){
					case '%':
						lgate();
						if(!ratfor)fprintf(fout,"# ");
						fprintf(fout,"define YYNEWLINE %d\n",ctable['\n']);
						if(!ratfor)fprintf(fout,"yylex(){\nint nstr; extern int yyprevious;\n");
						sectbegin = TRUE;
						i = treesize*(sizeof(*name)+sizeof(*left)+
							sizeof(*right)+sizeof(*nullstr)+sizeof(*parent))+ALITTLEEXTRA;
						c = myalloc(i,1);
						if(c == 0)
							error("Too little core for parse tree");
						p = c;
						cfree(p,i,1);
						name = myalloc(treesize,sizeof(*name));
						left = myalloc(treesize,sizeof(*left));
						right = myalloc(treesize,sizeof(*right));
						nullstr = myalloc(treesize,sizeof(*nullstr));
						parent = myalloc(treesize,sizeof(*parent));
						if(name == 0 || left == 0 || right == 0 || parent == 0 || nullstr == 0)
							error("Too little core for parse tree");
						return(freturn(DELIM));
					case 'p': case 'P':	/* has overridden number of positions */
						while(*p && !digit(*p))p++;
						maxpos = siconv(p);
# ifdef DEBUG
						if (debug) printf("positions (%%p) now %d\n",maxpos);
# endif
						if(report == 2)report = 1;
						continue;
					case 'n': case 'N':	/* has overridden number of states */
						while(*p && !digit(*p))p++;
						nstates = siconv(p);
# ifdef DEBUG
						if(debug)printf( " no. states (%%n) now %d\n",nstates);
# endif
						if(report == 2)report = 1;
						continue;
					case 'e': case 'E':		/* has overridden number of tree nodes */
						while(*p && !digit(*p))p++;
						treesize = siconv(p);
# ifdef DEBUG
						if (debug) printf("treesize (%%e) now %d\n",treesize);
# endif
						if(report == 2)report = 1;
						continue;
					case 'o': case 'O':
						while (*p && !digit(*p))p++;
						outsize = siconv(p);
						if (report ==2) report=1;
						continue;
					case 'a': case 'A':		/* has overridden number of transitions */
						while(*p && !digit(*p))p++;
						if(report == 2)report = 1;
						ntrans = siconv(p);
# ifdef DEBUG
						if (debug)printf("N. trans (%%a) now %d\n",ntrans);
# endif
						continue;
					case 'k': case 'K': /* overriden packed char classes */
						while (*p && !digit(*p))p++;
						if (report==2) report=1;
						cfree(pchar, pchlen, sizeof(*pchar));
						pchlen = siconv(p);
# ifdef DEBUG
						if (debug) printf( "Size classes (%%k) now %d\n",pchlen);
# endif
						pchar=pcptr=myalloc(pchlen, sizeof(*pchar));
						continue;
					case 't': case 'T': 	/* character set specifier */
						ZCH = atoi(p+2);
						if (ZCH < NCH) ZCH = NCH;
						if (ZCH > 2*NCH) error("ch table needs redeclaration");
						chset = TRUE;
						for(i = 0; i<ZCH; i++)
							ctable[i] = 0;
						while(getl(p) && scomp(p,"%T") != 0 && scomp(p,"%t") != 0){
							if((n = siconv(p)) <= 0 || n > ZCH){
								warning("Character value %d out of range",n);
								continue;
								}
							while(!space(*p) && *p) p++;
							while(space(*p)) p++;
							t = p;
							while(*t){
								c = ctrans(&t);
								if(ctable[c]){
									if (printable(c))
										warning("Character '%c' used twice",c);
									else
										warning("Character %o used twice",c);
									}
								else ctable[c] = n;
								t++;
								}
							p = buf;
							}
						{
						char chused[2*NCH]; int kr;
						for(i=0; i<ZCH; i++)
							chused[i]=0;
						for(i=0; i<NCH; i++)
							chused[ctable[i]]=1;
						for(kr=i=1; i<NCH; i++)
							if (ctable[i]==0)
								{
								while (chused[kr] == 0)
									kr++;
								ctable[i]=kr;
								chused[kr]=1;
								}
						}
						lgate();
						continue;
					case 'r': case 'R':
						c = 'r';
					case 'c': case 'C':
						if(lgatflg)
							error("Too late for language specifier");
						ratfor = (c == 'r');
						continue;
					case '{':
						lgate();
						while(getl(p) && scomp(p,"%}") != 0)
							fprintf(fout, "%s\n",p);
						if(p[0] == '%') continue;