y2.c

unix v7是最后一个广泛发布的研究型UNIX版本

			case '\'': val = '\''; break;
			case '"': val = '"'; break;
			case '\\': val = '\\'; break;
			default: error( "invalid escape" );
				}
			}
		else if( s[2] <= '7' && s[2]>='0' ){ /* \nnn sequence */
			if( s[3]<'0' || s[3] > '7' || s[4]<'0' ||
				s[4]>'7' || s[5] != '\0' ) error("illegal \\nnn construction" );
			val = 64*s[2] + 8*s[3] + s[4] - 73*'0';
			if( val == 0 ) error( "'\\000' is illegal" );
			}
		}
	else {
		val = extval++;
		}
	tokset[ntokens].value = val;
	toklev[ntokens] = 0;
	return( ntokens );
	}

defout(){ /* write out the defines (at the end of the declaration section) */

	register int i, c;
	register char *cp;

	for( i=ndefout; i<=ntokens; ++i ){

		cp = tokset[i].name;
		if( *cp == ' ' ) ++cp;  /* literals */

		for( ; (c= *cp)!='\0'; ++cp ){

			if( islower(c) || isupper(c) || isdigit(c) || c=='_' );  /* VOID */
			else goto nodef;
			}

		fprintf( ftable, "# define %s %d\n", tokset[i].name, tokset[i].value );
		if( fdefine != NULL ) fprintf( fdefine, "# define %s %d\n", tokset[i].name, tokset[i].value );

	nodef:	;
		}

	ndefout = ntokens+1;

	}

char *
cstash( s ) register char *s; {
	char *temp;

	temp = cnamp;
	do {
		if( cnamp >= &cnames[cnamsz] ) error("too many characters in id's and literals" );
		else *cnamp++ = *s;
		}  while ( *s++ );
	return( temp );
	}

gettok() {
	register i, base;
	static int peekline; /* number of '\n' seen in lookahead */
	register c, match, reserve;

begin:
	reserve = 0;
	lineno += peekline;
	peekline = 0;
	c = getc(finput);
	while( c==' ' || c=='\n' || c=='\t' || c=='\f' ){
		if( c == '\n' ) ++lineno;
		c=getc(finput);
		}
	if( c == '/' ){ /* skip comment */
		lineno += skipcom();
		goto begin;
		}

	switch(c){

	case EOF:
		return(ENDFILE);
	case '{':
		ungetc( c, finput );
		return( '=' );  /* action ... */
	case '<':  /* get, and look up, a type name (union member name) */
		i = 0;
		while( (c=getc(finput)) != '>' && c>=0 && c!= '\n' ){
			tokname[i] = c;
			if( ++i >= NAMESIZE ) --i;
			}
		if( c != '>' ) error( "unterminated < ... > clause" );
		tokname[i] = '\0';
		for( i=1; i<=ntypes; ++i ){
			if( !strcmp( typeset[i], tokname ) ){
				numbval = i;
				return( TYPENAME );
				}
			}
		typeset[numbval = ++ntypes] = cstash( tokname );
		return( TYPENAME );

	case '"':	
	case '\'':
		match = c;
		tokname[0] = ' ';
		i = 1;
		for(;;){
			c = getc(finput);
			if( c == '\n' || c == EOF )
				error("illegal or missing ' or \"" );
			if( c == '\\' ){
				c = getc(finput);
				tokname[i] = '\\';
				if( ++i >= NAMESIZE ) --i;
				}
			else if( c == match ) break;
			tokname[i] = c;
			if( ++i >= NAMESIZE ) --i;
			}
		break;

	case '%':
	case '\\':

		switch(c=getc(finput)) {

		case '0':	return(TERM);
		case '<':	return(LEFT);
		case '2':	return(BINARY);
		case '>':	return(RIGHT);
		case '%':
		case '\\':	return(MARK);
		case '=':	return(PREC);
		case '{':	return(LCURLY);
		default:	reserve = 1;
			}

	default:

		if( isdigit(c) ){ /* number */
			numbval = c-'0' ;
			base = (c=='0') ? 8 : 10 ;
			for( c=getc(finput); isdigit(c) ; c=getc(finput) ){
				numbval = numbval*base + c - '0';
				}
			ungetc( c, finput );
			return(NUMBER);
			}
		else if( islower(c) || isupper(c) || c=='_' || c=='.' || c=='$' ){
			i = 0;
			while( islower(c) || isupper(c) || isdigit(c) || c=='_' || c=='.' || c=='$' ){
				tokname[i] = c;
				if( reserve && isupper(c) ) tokname[i] += 'a'-'A';
				if( ++i >= NAMESIZE ) --i;
				c = getc(finput);
				}
			}
		else return(c);

		ungetc( c, finput );
		}

	tokname[i] = '\0';

	if( reserve ){ /* find a reserved word */
		if( !strcmp(tokname,"term")) return( TERM );
		if( !strcmp(tokname,"token")) return( TERM );
		if( !strcmp(tokname,"left")) return( LEFT );
		if( !strcmp(tokname,"nonassoc")) return( BINARY );
		if( !strcmp(tokname,"binary")) return( BINARY );
		if( !strcmp(tokname,"right")) return( RIGHT );
		if( !strcmp(tokname,"prec")) return( PREC );
		if( !strcmp(tokname,"start")) return( START );
		if( !strcmp(tokname,"type")) return( TYPEDEF );
		if( !strcmp(tokname,"union")) return( UNION );
		error("invalid escape, or illegal reserved word: %s", tokname );
		}

	/* look ahead to distinguish IDENTIFIER from C_IDENTIFIER */

	c = getc(finput);
	while( c==' ' || c=='\t'|| c=='\n' || c=='\f' || c== '/' ) {
		if( c == '\n' ) ++peekline;
		else if( c == '/' ){ /* look for comments */
			peekline += skipcom();
			}
		c = getc(finput);
		}
	if( c == ':' ) return( C_IDENTIFIER );
	ungetc( c, finput );
	return( IDENTIFIER );
}

fdtype( t ){ /* determine the type of a symbol */
	register v;
	if( t >= NTBASE ) v = nontrst[t-NTBASE].tvalue;
	else v = TYPE( toklev[t] );
	if( v <= 0 ) error( "must specify type for %s", (t>=NTBASE)?nontrst[t-NTBASE].name:
			tokset[t].name );
	return( v );
	}

chfind( t, s ) register char *s; {
	int i;

	if (s[0]==' ')t=0;
	TLOOP(i){
		if(!strcmp(s,tokset[i].name)){
			return( i );
			}
		}
	NTLOOP(i){
		if(!strcmp(s,nontrst[i].name)) {
			return( i+NTBASE );
			}
		}
	/* cannot find name */
	if( t>1 )
		error( "%s should have been defined earlier", s );
	return( defin( t, s ) );
	}

cpyunion(){
	/* copy the union declaration to the output, and the define file if present */

	int level, c;
	fprintf( ftable, "\n# line %d \"%s\"\n", lineno, infile );
	fprintf( ftable, "typedef union " );
	if( fdefine ) fprintf( fdefine, "\ntypedef union " );

	level = 0;
	for(;;){
		if( (c=getc(finput)) < 0 ) error( "EOF encountered while processing %%union" );
		putc( c, ftable );
		if( fdefine ) putc( c, fdefine );

		switch( c ){

		case '\n':
			++lineno;
			break;

		case '{':
			++level;
			break;

		case '}':
			--level;
			if( level == 0 ) { /* we are finished copying */
				fprintf( ftable, " YYSTYPE;\n" );
				if( fdefine ) fprintf( fdefine, " YYSTYPE;\nextern YYSTYPE yylval;\n" );
				return;
				}
			}
		}
	}

cpycode(){ /* copies code between \{ and \} */

	int c;
	c = getc(finput);
	if( c == '\n' ) {
		c = getc(finput);
		lineno++;
		}
	fprintf( ftable, "\n# line %d \"%s\"\n", lineno, infile );
	while( c>=0 ){
		if( c=='\\' )
			if( (c=getc(finput)) == '}' ) return;
			else putc('\\', ftable );
		if( c=='%' )
			if( (c=getc(finput)) == '}' ) return;
			else putc('%', ftable );
		putc( c , ftable );
		if( c == '\n' ) ++lineno;
		c = getc(finput);
		}
	error("eof before %%}" );
	}

skipcom(){ /* skip over comments */
	register c, i=0;  /* i is the number of lines skipped */

	/* skipcom is called after reading a / */

	if( getc(finput) != '*' ) error( "illegal comment" );
	c = getc(finput);
	while( c != EOF ){
		while( c == '*' ){
			if( (c=getc(finput)) == '/' ) return( i );
			}
		if( c == '\n' ) ++i;
		c = getc(finput);
		}
	error( "EOF inside comment" );
	/* NOTREACHED */
	}

cpyact(offset){ /* copy C action to the next ; or closing } */
	int brac, c, match, j, s, tok;

	fprintf( faction, "\n# line %d \"%s\"\n", lineno, infile );

	brac = 0;

loop:
	c = getc(finput);
swt:
	switch( c ){

case ';':
		if( brac == 0 ){
			putc( c , faction );
			return;
			}
		goto lcopy;

case '{':
		brac++;
		goto lcopy;

case '$':
		s = 1;
		tok = -1;
		c = getc(finput);
		if( c == '<' ){ /* type description */
			ungetc( c, finput );
			if( gettok() != TYPENAME ) error( "bad syntax on $<ident> clause" );
			tok = numbval;
			c = getc(finput);
			}
		if( c == '$' ){
			fprintf( faction, "yyval");
			if( ntypes ){ /* put out the proper tag... */
				if( tok < 0 ) tok = fdtype( *prdptr[nprod] );
				fprintf( faction, ".%s", typeset[tok] );
				}
			goto loop;
			}
		if( c == '-' ){
			s = -s;
			c = getc(finput);
			}
		if( isdigit(c) ){
			j=0;
			while( isdigit(c) ){
				j= j*10+c-'0';
				c = getc(finput);
				}

			j = j*s - offset;
			if( j > 0 ){
				error( "Illegal use of $%d", j+offset );
				}

			fprintf( faction, "yypvt[-%d]", -j );
			if( ntypes ){ /* put out the proper tag */
				if( j+offset <= 0 && tok < 0 ) error( "must specify type of $%d", j+offset );
				if( tok < 0 ) tok = fdtype( prdptr[nprod][j+offset] );
				fprintf( faction, ".%s", typeset[tok] );
				}
			goto swt;
			}
		putc( '$' , faction );
		if( s<0 ) putc('-', faction );
		goto swt;

case '}':
		if( --brac ) goto lcopy;
		putc( c, faction );
		return;


case '/':	/* look for comments */
		putc( c , faction );
		c = getc(finput);
		if( c != '*' ) goto swt;

		/* it really is a comment */

		putc( c , faction );
		c = getc(finput);
		while( c != EOF ){
			while( c=='*' ){
				putc( c , faction );
				if( (c=getc(finput)) == '/' ) goto lcopy;
				}
			putc( c , faction );
			if( c == '\n' )++lineno;
			c = getc(finput);
			}
		error( "EOF inside comment" );

case '\'':	/* character constant */
		match = '\'';
		goto string;

case '"':	/* character string */
		match = '"';

	string:

		putc( c , faction );
		while( c=getc(finput) ){

			if( c=='\\' ){
				putc( c , faction );
				c=getc(finput);
				if( c == '\n' ) ++lineno;
				}
			else if( c==match ) goto lcopy;
			else if( c=='\n' ) error( "newline in string or char. const." );
			putc( c , faction );
			}
		error( "EOF in string or character constant" );

case EOF:
		error("action does not terminate" );

case '\n':	++lineno;
		goto lcopy;

		}

lcopy:
	putc( c , faction );
	goto loop;
	}