lex.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

		quote = *i;
		*j = MYQUOTE; /* special marker */
		for(;;)
			{
			if(++i > lastch)
				{
				err("unbalanced quotes; closing quote supplied");
				break;
				}
			if(*i == quote)
				if(i<lastch && i[1]==quote) ++i;
				else break;
			else if(*i=='\\' && i<lastch)
				switch(*++i)
					{
					case 't':
						*i = '\t'; break;
					case 'b':
						*i = '\b'; break;
					case 'n':
						*i = '\n'; break;
					case 'f':
						*i = '\f'; break;
					case 'v':
						*i = '\v'; break;
					case '0':
						*i = '\0'; break;
					default:
						break;
					}
			*++j = *i;
			}
		j[1] = MYQUOTE;
		j += 2;
		prvstr = j;
		}
	else if( (*i=='h' || *i=='H')  && j>prvstr)	/* test for Hollerith strings */
		{
		if( ! isdigit(j[-1])) goto copychar;
		nh = j[-1] - '0';
		ten = 10;
		j1 = prvstr - 1;
		if (j1<j-5) j1=j-5;
		for(j0=j-2 ; j0>j1; -- j0)
			{
			if( ! isdigit(*j0 ) ) break;
			nh += ten * (*j0-'0');
			ten*=10;
			}
		if(j0 <= j1) goto copychar;
/* a hollerith must be preceded by a punctuation mark.
   '*' is possible only as repetition factor in a data statement
   not, in particular, in character*2h
*/

		if( !(*j0=='*'&&s[0]=='d') && *j0!='/' && *j0!='(' &&
			*j0!=',' && *j0!='=' && *j0!='.')
				goto copychar;
		if(i+nh > lastch)
			{
			erri("%dH too big", nh);
			nh = lastch - i;
			}
		j0[1] = MYQUOTE; /* special marker */
		j = j0 + 1;
		while(nh-- > 0)
			{
			if(*++i == '\\')
				switch(*++i)
					{
					case 't':
						*i = '\t'; break;
					case 'b':
						*i = '\b'; break;
					case 'n':
						*i = '\n'; break;
					case 'f':
						*i = '\f'; break;
					case '0':
						*i = '\0'; break;
					default:
						break;
					}
			*++j = *i;
			}
		j[1] = MYQUOTE;
		j+=2;
		prvstr = j;
		}
	else	{
		if(*i == '(') ++parlev;
		else if(*i == ')') --parlev;
		else if(parlev == 0)
			if(*i == '=') expeql = 1;
			else if(*i == ',') expcom = 1;
copychar:		/*not a string or space -- copy, shifting case if necessary */
		if(shiftcase && isupper(*i))
			*j++ = tolower(*i);
		else	*j++ = *i;
		}
	}
lastch = j - 1;
nextch = s;
}

LOCAL analyz()
{
register char *i;

	if(parlev != 0)
		{
		err("unbalanced parentheses, statement skipped");
		stkey = SUNKNOWN;
		return;
		}
	if(nextch+2<=lastch && nextch[0]=='i' && nextch[1]=='f' && nextch[2]=='(')
		{
/* assignment or if statement -- look at character after balancing paren */
		parlev = 1;
		for(i=nextch+3 ; i<=lastch; ++i)
			if(*i == (MYQUOTE))
				{
				while(*++i != MYQUOTE)
					;
				}
			else if(*i == '(')
				++parlev;
			else if(*i == ')')
				{
				if(--parlev == 0)
					break;
				}
		if(i >= lastch)
			stkey = SLOGIF;
		else if(i[1] == '=')
			stkey = SLET;
		else if( isdigit(i[1]) )
			stkey = SARITHIF;
		else	stkey = SLOGIF;
		if(stkey != SLET)
			nextch += 2;
		}
	else if(expeql) /* may be an assignment */
		{
		if(expcom && nextch<lastch &&
			nextch[0]=='d' && nextch[1]=='o')
				{
				stkey = SDO;
				nextch += 2;
				}
		else	stkey = SLET;
		}
/* otherwise search for keyword */
	else	{
		stkey = getkwd();
		if(stkey==SGOTO && lastch>=nextch)
			if(nextch[0]=='(')
				stkey = SCOMPGOTO;
			else if(isalpha(nextch[0]))
				stkey = SASGOTO;
		}
	parlev = 0;
}



LOCAL getkwd()
{
register char *i, *j;
register struct Keylist *pk, *pend;
int k;

if(! isalpha(nextch[0]) )
	return(SUNKNOWN);
k = nextch[0] - 'a';
if(pk = keystart[k])
	for(pend = keyend[k] ; pk<=pend ; ++pk )
		{
		i = pk->keyname;
		j = nextch;
		while(*++i==*++j && *i!='\0')
			;
		if(*i=='\0' && j<=lastch+1)
			{
			nextch = j;
#ifdef ONLY66
			if(no66flag && pk->notinf66)
				errstr("Not a Fortran 66 keyword: %s",
					pk->keyname);
#endif
			return(pk->keyval);
			}
		}
return(SUNKNOWN);
}



initkey()
{
extern struct Keylist keys[];
register struct Keylist *p;
register int i,j;

for(i = 0 ; i<26 ; ++i)
	keystart[i] = NULL;

for(p = keys ; p->keyname ; ++p)
	{
	j = p->keyname[0] - 'a';
	if(keystart[j] == NULL)
		keystart[j] = p;
	keyend[j] = p;
	}
}

LOCAL gettok()
{
int havdot, havexp, havdbl;
int radix, val;
extern struct Punctlist puncts[];
struct Punctlist *pp;
extern struct Fmtlist fmts[];
extern struct Dotlist dots[];
struct Dotlist *pd;

char *i, *j, *n1, *p;

	if(*nextch == (MYQUOTE))
		{
		++nextch;
		p = token;
		while(*nextch != MYQUOTE)
			*p++ = *nextch++;
		++nextch;
		toklen = p - token;
		*p = '\0';
		return (SHOLLERITH);
		}
/*
	if(stkey == SFORMAT)
		{
		for(pf = fmts; pf->fmtchar; ++pf)
			{
			if(*nextch == pf->fmtchar)
				{
				++nextch;
				if(pf->fmtval == SLPAR)
					++parlev;
				else if(pf->fmtval == SRPAR)
					--parlev;
				return(pf->fmtval);
				}
			}
		if( isdigit(*nextch) )
			{
			p = token;
			*p++ = *nextch++;
			while(nextch<=lastch && isdigit(*nextch) )
				*p++ = *nextch++;
			toklen = p - token;
			*p = '\0';
			if(nextch<=lastch && *nextch=='p')
				{
				++nextch;
				return(SSCALE);
				}
			else	return(SICON);
			}
		if( isalpha(*nextch) )
			{
			p = token;
			*p++ = *nextch++;
			while(nextch<=lastch &&
				(*nextch=='.' || isdigit(*nextch) || isalpha(*nextch) ))
					*p++ = *nextch++;
			toklen = p - token;
			*p = '\0';
			return(SFIELD);
			}
		goto badchar;
		}
/* Not a format statement */

if(needkwd)
	{
	needkwd = 0;
	return( getkwd() );
	}

	for(pp=puncts; pp->punchar; ++pp)
		if(*nextch == pp->punchar)
			{
			if( (*nextch=='*' || *nextch=='/') &&
				nextch<lastch && nextch[1]==nextch[0])
					{
					if(*nextch == '*')
						val = SPOWER;
					else	val = SCONCAT;
					nextch+=2;
					}
			else	{
				val = pp->punval;
				if(val==SLPAR)
					++parlev;
				else if(val==SRPAR)
					--parlev;
				++nextch;
				}
			return(val);
			}
	if(*nextch == '.')
		if(nextch >= lastch) goto badchar;
		else if(isdigit(nextch[1])) goto numconst;
		else	{
			for(pd=dots ; (j=pd->dotname) ; ++pd)
				{
				for(i=nextch+1 ; i<=lastch ; ++i)
					if(*i != *j) break;
					else if(*i != '.') ++j;
					else	{
						nextch = i+1;
						return(pd->dotval);
						}
				}
			goto badchar;
			}
	if( isalpha(*nextch) )
		{
		p = token;
		*p++ = *nextch++;
		while(nextch<=lastch)
			if( isalpha(*nextch) || isdigit(*nextch) )
				*p++ = *nextch++;
			else break;
		toklen = p - token;
		*p = '\0';
		if(inioctl && nextch<=lastch && *nextch=='=')
			{
			++nextch;
			return(SNAMEEQ);
			}
		if(toklen>8 && eqn(8,token,"function") && isalpha(token[8]) &&
			nextch<lastch && nextch[0]=='(' &&
			(nextch[1]==')' | isalpha(nextch[1])) )
				{
				nextch -= (toklen - 8);
				return(SFUNCTION);
				}
		if(toklen > VL)
			{
			char buff[30];
			sprintf(buff, "name %s too long, truncated to %d",
				token, VL);
			err(buff);
			toklen = VL;
			token[VL] = '\0';
			}
		if(toklen==1 && *nextch==MYQUOTE)
			{
			switch(token[0])
				{
				case 'z':  case 'Z':
				case 'x':  case 'X':
					radix = 16; break;
				case 'o':  case 'O':
					radix = 8; break;
				case 'b':  case 'B':
					radix = 2; break;
				default:
					err("bad bit identifier");
					return(SNAME);
				}
			++nextch;
			for(p = token ; *nextch!=MYQUOTE ; )
				if ( *nextch == BLANK || *nextch == '\t')
					nextch++;
				else
					{
					if (isupper(*nextch))
						*nextch = tolower(*nextch);
					if (hextoi(*p++ = *nextch++) >= radix)
						{
						err("invalid binary character");
						break;
						}
					}
			++nextch;
			toklen = p - token;
			return( radix==16 ? SHEXCON :
				(radix==8 ? SOCTCON : SBITCON) );
			}
		return(SNAME);
		}
	if( ! isdigit(*nextch) ) goto badchar;
numconst:
	havdot = NO;
	havexp = NO;
	havdbl = NO;
	for(n1 = nextch ; nextch<=lastch ; ++nextch)
		{
		if(*nextch == '.')
			if(havdot) break;
			else if(nextch+2<=lastch && isalpha(nextch[1])
				&& isalpha(nextch[2]))
					break;
			else	havdot = YES;
		else if( !intonly && (*nextch=='d' || *nextch=='e') )
			{
			p = nextch;
			havexp = YES;
			if(*nextch == 'd')
				havdbl = YES;
			if(nextch<lastch)
				if(nextch[1]=='+' || nextch[1]=='-')
					++nextch;
			if( (nextch >= lastch) || ! isdigit(*++nextch) )
				{
				nextch = p;
				havdbl = havexp = NO;
				break;
				}
			for(++nextch ;
				nextch<=lastch && isdigit(*nextch);
				++nextch);
			break;
			}
		else if( ! isdigit(*nextch) )
			break;
		}
	p = token;
	i = n1;
	while(i < nextch)
		*p++ = *i++;
	toklen = p - token;
	*p = '\0';
	if(havdbl) return(SDCON);
	if(havdot || havexp) return( dblflag ? SDCON : SRCON);
	return(SICON);
badchar:
	s[0] = *nextch++;
	return(SUNKNOWN);
}

/* KEYWORD AND SPECIAL CHARACTER TABLES
*/

struct Punctlist puncts[ ] =
	{
	'(', SLPAR,
	')', SRPAR,
	'=', SEQUALS,
	',', SCOMMA,
	'+', SPLUS,
	'-', SMINUS,
	'*', SSTAR,
	'/', SSLASH,
	'$', SCURRENCY,
	':', SCOLON,
	0, 0 } ;

/*
LOCAL struct Fmtlist  fmts[ ] =
	{
	'(', SLPAR,
	')', SRPAR,
	'/', SSLASH,
	',', SCOMMA,
	'-', SMINUS,
	':', SCOLON,
	0, 0 } ;
*/

LOCAL struct Dotlist  dots[ ] =
	{
	"and.", SAND, 
	"or.", SOR, 
	"not.", SNOT, 
	"true.", STRUE, 
	"false.", SFALSE, 
	"eq.", SEQ, 
	"ne.", SNE, 
	"lt.", SLT, 
	"le.", SLE, 
	"gt.", SGT, 
	"ge.", SGE, 
	"neqv.", SNEQV, 
	"eqv.", SEQV, 
	0, 0 } ;

LOCAL struct Keylist  keys[ ] =
	{
	 	{ "assign",  SASSIGN  },
	 	{ "automatic",  SAUTOMATIC, YES  },
	 	{ "backspace",  SBACKSPACE  },
	 	{ "blockdata",  SBLOCK  },
	 	{ "call",  SCALL  },
	 	{ "character",  SCHARACTER, YES  },
	 	{ "close",  SCLOSE, YES  },
	 	{ "common",  SCOMMON  },
	 	{ "complex",  SCOMPLEX  },
	 	{ "continue",  SCONTINUE  },
	 	{ "data",  SDATA  },
	 	{ "dimension",  SDIMENSION  },
	 	{ "doubleprecision",  SDOUBLE  },
	 	{ "doublecomplex", SDCOMPLEX, YES  },
	 	{ "elseif",  SELSEIF, YES  },
	 	{ "else",  SELSE, YES  },
	 	{ "endfile",  SENDFILE  },
	 	{ "endif",  SENDIF, YES  },
	 	{ "end",  SEND  },
	 	{ "entry",  SENTRY, YES  },
	 	{ "equivalence",  SEQUIV  },
	 	{ "external",  SEXTERNAL  },
	 	{ "format",  SFORMAT  },
	 	{ "function",  SFUNCTION  },
	 	{ "goto",  SGOTO  },
	 	{ "implicit",  SIMPLICIT, YES  },
	 	{ "include",  SINCLUDE, YES  },
	 	{ "inquire",  SINQUIRE, YES  },
	 	{ "intrinsic",  SINTRINSIC, YES  },
	 	{ "integer",  SINTEGER  },
	 	{ "logical",  SLOGICAL  },
#ifdef NAMELIST
		{ "namelist", SNAMELIST, YES },
#endif
		{ "none", SUNDEFINED, YES },
	 	{ "open",  SOPEN, YES  },
	 	{ "parameter",  SPARAM, YES  },
	 	{ "pause",  SPAUSE  },
	 	{ "print",  SPRINT  },
	 	{ "program",  SPROGRAM, YES  },
	 	{ "punch",  SPUNCH, YES  },
	 	{ "read",  SREAD  },
	 	{ "real",  SREAL  },
	 	{ "return",  SRETURN  },
	 	{ "rewind",  SREWIND  },
	 	{ "save",  SSAVE, YES  },
	 	{ "static",  SSTATIC, YES  },
	 	{ "stop",  SSTOP  },
	 	{ "subroutine",  SSUBROUTINE  },
	 	{ "then",  STHEN, YES  },
	 	{ "undefined", SUNDEFINED, YES  },
	 	{ "write",  SWRITE  },
			{ 0, 0 }
	};