yap-6.3/os/pl-read.c

#include "pl-incl.h"
#include "pl-ctype.h"
#include "pl-utf8.h"
#include "pl-dtoa.h"
#include "pl-umap.c"			/* Unicode map */

#include "pl-read.h"			/* read structure */

/**
 *  @defgroup ReadTerm Read Term from Streams
 *  @ingroup  InputOutput
 * @{
 */

static bool
isStringStream(IOSTREAM *s)
{ return s->functions == &Sstringfunctions;
}



void
init_read_data(ReadData _PL_rd, IOSTREAM *in ARG_LD)
{  CACHE_REGS
	memset(_PL_rd, 0, sizeof(*_PL_rd));	/* optimise! */

_PL_rd->magic = RD_MAGIC;
_PL_rd->varnames = 0;
_PL_rd->module = Yap_GetModuleEntry(CurrentModule);
_PL_rd->exception = PL_new_term_ref();
rb.stream = in;
_PL_rd->has_exception = 0;
_PL_rd->module = MODULE_parse;
_PL_rd->flags  = _PL_rd->module->flags; /* change for options! */
_PL_rd->styleCheck = debugstatus.styleCheck;
_PL_rd->on_error = ATOM_error;
_PL_rd->backquoted_string = truePrologFlag(PLFLAG_BACKQUOTED_STRING);
}

void
free_read_data(ReadData _PL_rd)
{
}

static int
read_term(term_t t, ReadData _PL_rd ARG_LD)
{
	return Yap_read_term(t, rb.stream, _PL_rd);
}


static void	  addUTF8Buffer(Buffer b, int c);

static void
addUTF8Buffer(Buffer b, int c)
{ if ( c >= 0x80 )
{ char buf[6];
char *p, *end;

end = utf8_put_char(buf, c);
for(p=buf; p<end; p++)
{ addBuffer(b, *p&0xff, char);
}
} else
{ addBuffer(b, c, char);
}
}

/*******************************
 *     UNICODE CLASSIFIERS      *
 *******************************/

#define CharTypeW(c, t, w) \
		((unsigned)(c) <= 0xff ? (_PL_char_types[(unsigned)(c)] t) \
				: (uflagsW(c) & (w)))

#define PlBlankW(c)     CharTypeW(c, == SP, U_SEPARATOR)
#define PlUpperW(c)     CharTypeW(c, == UC, U_UPPERCASE)
#define PlIdStartW(c)   (c <= 0xff ? (isLower(c)||isUpper(c)||c=='_') \
		: uflagsW(c) & U_ID_START)
#define PlIdContW(c)    CharTypeW(c, >= UC, U_ID_CONTINUE)
#define PlSymbolW(c)    CharTypeW(c, == SY, U_SYMBOL)
#define PlPunctW(c)     CharTypeW(c, == PU, 0)
#define PlSoloW(c)      CharTypeW(c, == SO, U_OTHER)
#define PlInvalidW(c)   (uflagsW(c) == 0)

int
f_is_prolog_var_start(wint_t c)
{ return PlIdStartW(c) && (PlUpperW(c) || c == '_');
}

int
f_is_prolog_atom_start(wint_t c)
{ return PlIdStartW(c) != 0;
}

int
f_is_prolog_identifier_continue(wint_t c)
{ return PlIdContW(c) || c == '_';
}

int
f_is_prolog_symbol(wint_t c)
{ return PlSymbolW(c) != 0;
}

int
unicode_separator(pl_wchar_t c)
{ return PlBlankW(c);
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
	FALSE	return false
	TRUE	redo
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static int
reportReadError(ReadData rd)
{ if ( rd->on_error == ATOM_error )
	return PL_raise_exception(rd->exception);
if ( rd->on_error != ATOM_quiet )
	printMessage(ATOM_error, PL_TERM, rd->exception);
PL_clear_exception();

if ( rd->on_error == ATOM_dec10 )
	return TRUE;

return FALSE;
}


/* static int */
/* reportSingletons(ReadData rd, singletons, Atom amod, Atom aname, UInt arity) */
/* {  */
/*   printMessage(ATOM_warning, PL_FUNCTOR_CHARS,  */
/* 	       "singletons", 2, */
/* 	       PL_TERM, singletons,  */
/* 	       PL_TERM, mod, */
/* 	       PL_FUNCTOR_divide2, */
/* 	       PL_ATOM, name, */
/* 	       PL_INT, arity); */

/*   return FALSE; */
/* } */


/********************************
 *           RAW READING         *
 *********************************/


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Scan the input, give prompts when necessary and return a char *  holding
a  stripped  version of the next term.  Contiguous white space is mapped
on a single space, block and % ... \n comment  is  deleted.   Memory  is
claimed automatically en enlarged if necessary.

(char *) NULL is returned on a syntax error.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define syntaxError(what, rd) { errorWarning(what, 0, rd); fail; }

static term_t
makeErrorTerm(const char *id_str, term_t id_term, ReadData _PL_rd)
{ GET_LD
	term_t ex, loc=0;			/* keep compiler happy */
unsigned char const *s, *ll = NULL;
int rc = TRUE;

if ( !(ex = PL_new_term_ref()) ||
		!(loc = PL_new_term_ref()) )
	rc = FALSE;

if ( rc && !id_term )
{ if ( !(id_term=PL_new_term_ref()) ||
		!PL_put_atom_chars(id_term, id_str) )
	rc = FALSE;
}

if ( rc )
	rc = PL_unify_term(ex,
			PL_FUNCTOR, FUNCTOR_error2,
			PL_FUNCTOR, FUNCTOR_syntax_error1,
			PL_TERM, id_term,
			PL_TERM, loc);

source_char_no += last_token_start - rdbase;
for(s=rdbase; s<last_token_start; s++)
{ if ( *s == '\n' )
{ source_line_no++;
ll = s+1;
}
}

if ( ll )
{ int lp = 0;

for(s = ll; s<last_token_start; s++)
{ switch(*s)
{ case '\b':
	if ( lp > 0 ) lp--;
	break;
case '\t':
	lp |= 7;
default:
	lp++;
}
}

source_line_pos = lp;
}

if ( rc )
{ if ( ReadingSource )			/* reading a file */
{ rc = PL_unify_term(loc,
		PL_FUNCTOR, FUNCTOR_file4,
		PL_ATOM, source_file_name,
		PL_INT, source_line_no,
		PL_INT, source_line_pos,
		PL_INT64, source_char_no);
} else if ( isStringStream(rb.stream) )
{ size_t pos;

pos = utf8_strlen((char *)rdbase, last_token_start-rdbase);

rc = PL_unify_term(loc,
		PL_FUNCTOR, FUNCTOR_string2,
		PL_UTF8_STRING, rdbase,
		PL_INT, (int)pos);
} else				/* any stream */
{ term_t stream;

if ( !(stream=PL_new_term_ref()) ||
		!PL_unify_stream_or_alias(stream, rb.stream) ||
		!PL_unify_term(loc,
				PL_FUNCTOR, FUNCTOR_stream4,
				PL_TERM, stream,
				PL_INT, source_line_no,
				PL_INT, source_line_pos,
				PL_INT64, source_char_no) )
	rc = FALSE;
}
}

return (rc ? ex : (term_t)0);
}



static bool
errorWarning(const char *id_str, term_t id_term, ReadData _PL_rd)
{ GET_LD
	term_t ex;

LD->exception.processing = TRUE;	/* allow using spare stack */

ex = makeErrorTerm(id_str, id_term, _PL_rd);

if ( _PL_rd )
{ _PL_rd->has_exception = TRUE;
if ( ex )
	PL_put_term(_PL_rd->exception, ex);
else
	PL_put_term(_PL_rd->exception, exception_term);
} else
{ if ( ex )
	PL_raise_exception(ex);
}

fail;
}



static void
clearBuffer(ReadData _PL_rd)
{ if (rb.size == 0)
{ rb.base = rb.fast;
rb.size = sizeof(rb.fast);
}
rb.end = rb.base + rb.size;
rdbase = rb.here = rb.base;

_PL_rd->posp = rdbase;
_PL_rd->posi = 0;
}


static void
growToBuffer(int c, ReadData _PL_rd)
{ if ( rb.base == rb.fast )		/* intptr_t clause: jump to use malloc() */
{ rb.base = PL_malloc(FASTBUFFERSIZE * 2);
memcpy(rb.base, rb.fast, FASTBUFFERSIZE);
} else
	rb.base = PL_realloc(rb.base, rb.size*2);

DEBUG(8, Sdprintf("Reallocated read buffer at %ld\n", (intptr_t) rb.base));
_PL_rd->posp = rdbase = rb.base;
rb.here = rb.base + rb.size;
rb.size *= 2;
rb.end  = rb.base + rb.size;
_PL_rd->posi = 0;

*rb.here++ = c;
}


static inline void
addByteToBuffer(int c, ReadData _PL_rd)
{ c &= 0xff;

if ( rb.here >= rb.end )
	growToBuffer(c, _PL_rd);
else
	*rb.here++ = c;
}


static void
addToBuffer(int c, ReadData _PL_rd)
{ if ( c <= 0x7f )
{ addByteToBuffer(c, _PL_rd);
} else
{ char buf[10];
char *s, *e;

e = utf8_put_char(buf, c);
for(s=buf; s<e; s++)
	addByteToBuffer(*s, _PL_rd);
}
}



#if __YAP_PROLOG__
void
Yap_setCurrentSourceLocation( void *rd )
{
	GET_LD
	setCurrentSourceLocation(rd PASS_LD);
}
#endif


static inline int
getchr__(ReadData _PL_rd)
{ int c = Sgetcode(rb.stream);

if ( !_PL_rd->char_conversion_table || c < 0 || c >= 256 )
	return c;

return _PL_rd->char_conversion_table[c];
}


#define getchr()  getchr__(_PL_rd)
#define getchrq() Sgetcode(rb.stream)

#define ensure_space(c) { if ( something_read && \
		(c == '\n' || !isBlank(rb.here[-1])) ) \
	addToBuffer(c, _PL_rd); \
}
#define set_start_line { if ( !something_read ) \
		{ setCurrentSourceLocation(_PL_rd PASS_LD); \
		something_read++; \
		} \
}





#ifdef O_QUASIQUOTATIONS
/** '$qq_open'(+QQRange, -Stream) is det.

Opens a quasi-quoted memory range.

@arg QQRange is a term '$quasi_quotation'(ReadData, Start, Length)
@arg Stream  is a UTF-8 encoded string, whose position indication
	     reflects the location in the real file.
 */

static
PRED_IMPL("$qq_open", 2, qq_open, 0)
{ PRED_LD

	if ( PL_is_functor(A1, FUNCTOR_dquasi_quotation3) )
	{ void *ptr;
	char * start;
	size_t len;
	term_t arg = PL_new_term_ref();
	IOSTREAM *s;

	if ( PL_get_arg(1, A1, arg) && PL_get_pointer_ex(arg, &ptr) &&
			PL_get_arg(2, A1, arg) && PL_get_intptr(arg, (intptr_t *)&start) &&
			PL_get_arg(3, A1, arg) && PL_get_intptr(arg, (intptr_t *)&len) )
	{  //source_location pos;
		if ( (s=Sopenmem(&start, &len, "r")) )
			s->encoding = ENC_UTF8;

		return PL_unify_stream(A2, s);
	}
	} else
		PL_type_error("read_context", A1);

return FALSE;
}


static int
parse_quasi_quotations(ReadData _PL_rd ARG_LD)
{ if ( _PL_rd->qq_tail )
{ term_t av;
int rc;

if ( !PL_unify_nil(_PL_rd->qq_tail) )
	return FALSE;

if ( !_PL_rd->quasi_quotations )
{ if ( (av = PL_new_term_refs(2)) &&
		PL_put_term(av+0, _PL_rd->qq) &&
#if __YAP_PROLOG__
		PL_put_atom(av+1, YAP_SWIAtomFromAtom(_PL_rd->module->AtomOfME)) &&
#else
		PL_put_atom(av+1, _PL_rd->module->name) &&
#endif
		PL_cons_functor_v(av, FUNCTOR_dparse_quasi_quotations2, av) )
{ term_t ex;
rc = callProlog(MODULE_system, av+0, PL_Q_CATCH_EXCEPTION, &ex);
if ( rc )
	return TRUE;
_PL_rd->exception = ex;
_PL_rd->has_exception = TRUE;
}
return FALSE;
} else
	return TRUE;
} else if ( _PL_rd->quasi_quotations )	/* user option, but no quotes */
{ return PL_unify_nil(_PL_rd->quasi_quotations);
} else
	return TRUE;
}


#endif /*O_QUASIQUOTATIONS*/




#define rawSyntaxError(what) { addToBuffer(EOS, _PL_rd); \
		rdbase = rb.base, last_token_start = rb.here-1; \
		syntaxError(what, _PL_rd); \
}

static int
raw_read_quoted(int q, ReadData _PL_rd)
{ int newlines = 0;
int c;

addToBuffer(q, _PL_rd);
while((c=getchrq()) != EOF && c != q)
{ if ( c == '\\' && DO_CHARESCAPE )
{ int base;
addToBuffer(c, _PL_rd);

switch( (c=getchrq()) )
{ case EOF:
	goto eofinstr;
case 'u':			/* \uXXXX */
case 'U':			/* \UXXXXXXXX */
	addToBuffer(c, _PL_rd);
	continue;
case 'x':			/* \xNN\ */
	addToBuffer(c, _PL_rd);
	c = getchrq();
	if ( c == EOF )
		goto eofinstr;
	if ( digitValue(16, c) >= 0 )
	{ base = 16;
	addToBuffer(c, _PL_rd);

	xdigits:
	c = getchrq();
	while( digitValue(base, c) >= 0 )
	{ addToBuffer(c, _PL_rd);
	c = getchrq();
	}
	}
	if ( c == EOF )
		goto eofinstr;
	addToBuffer(c, _PL_rd);
	if ( c == q )
		return TRUE;
	continue;
default:
	addToBuffer(c, _PL_rd);
	if ( digitValue(8, c) >= 0 )	/* \NNN\ */
	{ base = 8;
	goto xdigits;
	} else if ( c == '\n' )	/* \<newline> */
	{ c = getchrq();
	if ( c == EOF )
		goto eofinstr;
	addToBuffer(c, _PL_rd);
	if ( c == q )
		return TRUE;
	}
	continue;			/* \symbolic-control-char */
}
} else if (c == '\n' &&
		newlines++ > MAXNEWLINES &&
		(_PL_rd->styleCheck & LONGATOM_CHECK))
{ rawSyntaxError("long_string");
}
addToBuffer(c, _PL_rd);
}
if (c == EOF)
{ eofinstr:
	rawSyntaxError("end_of_file_in_string");
}
addToBuffer(c, _PL_rd);

return TRUE;
}


static int
add_comment(Buffer b, IOPOS *pos, ReadData _PL_rd ARG_LD)
{ term_t head = PL_new_term_ref();

assert(_PL_rd->comments);
if ( !PL_unify_list(_PL_rd->comments, head, _PL_rd->comments) )
	return FALSE;
if ( pos )
{ if ( !PL_unify_term(head,
		PL_FUNCTOR, FUNCTOR_minus2,
		PL_FUNCTOR, FUNCTOR_stream_position4,
		PL_INT64, pos->charno,
		PL_INT, pos->lineno,
		PL_INT, pos->linepos,
		PL_INT, 0,
		PL_UTF8_STRING, baseBuffer(b, char)) )
	return FALSE;
} else
{ if ( !PL_unify_term(head,
		PL_FUNCTOR, FUNCTOR_minus2,
		ATOM_minus,
		PL_UTF8_STRING, baseBuffer(b, char)) )
	return FALSE;
}

PL_reset_term_refs(head);
return TRUE;
}


static void
setErrorLocation(IOPOS *pos, ReadData _PL_rd)
{ if ( pos )
{ GET_LD

	source_char_no = pos->charno;
source_line_pos = pos->linepos;
source_line_no = pos->lineno;
}
rb.here = rb.base+1;			/* see rawSyntaxError() */
}


static unsigned char *
raw_read2(ReadData _PL_rd ARG_LD)
{ int c;
bool something_read = FALSE;
bool dotseen = FALSE;
IOPOS pbuf;					/* comment start */
IOPOS *pos;

clearBuffer(_PL_rd);				/* clear input buffer */
_PL_rd->strictness = truePrologFlag(PLFLAG_ISO);
source_line_no = -1;

for(;;)
{ c = getchr();

handle_c:
switch(c)
{ case EOF:
	if ( isStringStream(rb.stream) ) /* do not require '. ' when */
	{ addToBuffer(' ', _PL_rd);     /* reading from a string */
	addToBuffer('.', _PL_rd);
	addToBuffer(' ', _PL_rd);
	addToBuffer(EOS, _PL_rd);
	return rb.base;
	}
	if (something_read)
	{ if ( dotseen )		/* term.<EOF> */
	{ if ( rb.here - rb.base == 1 )
		rawSyntaxError("end_of_clause");
	ensure_space(' ');
	addToBuffer(EOS, _PL_rd);
	return rb.base;
	}
	rawSyntaxError("end_of_file");
	}
	if ( Sfpasteof(rb.stream) )
	{ term_t stream;

	LD->exception.processing = TRUE;
	stream = PL_new_term_ref();
	PL_unify_stream_or_alias(stream, rb.stream);
	PL_error(NULL, 0, NULL, ERR_PERMISSION,
			ATOM_input, ATOM_past_end_of_stream, stream);
	return NULL;
	}
	set_start_line;
	strcpy((char *)rb.base, "end_of_file. ");
	rb.here = rb.base + 14;
	return rb.base;
case '/': if ( rb.stream->position )
{ pbuf = *rb.stream->position;
pbuf.charno--;
pbuf.linepos--;
pos = &pbuf;
} else
	pos = NULL;

c = getchr();
if ( c == '*' )
{ int last;
int level = 1;
union {
	tmp_buffer ctmpbuf;
	buffer tmpbuf;
} u;
Buffer cbuf;

if ( _PL_rd->comments )
{ initBuffer(&u.ctmpbuf);
cbuf = &u.tmpbuf;
addUTF8Buffer(cbuf, '/');
addUTF8Buffer(cbuf, '*');
} else
{ cbuf = NULL;
}

if ((last = getchr()) == EOF)
{ if ( cbuf )
	discardBuffer(cbuf);
setErrorLocation(pos, _PL_rd);
rawSyntaxError("end_of_file_in_block_comment");
}
if ( cbuf )
	addUTF8Buffer(cbuf, last);

if ( something_read )
{ addToBuffer(' ', _PL_rd);	/* positions */
addToBuffer(' ', _PL_rd);
addToBuffer(last == '\n' ? last : ' ', _PL_rd);
}

for(;;)
{ c = getchr();

if ( cbuf )
	addUTF8Buffer(cbuf, c);

switch( c )
{ case EOF:
	if ( cbuf )
		discardBuffer(cbuf);
	setErrorLocation(pos, _PL_rd);
	rawSyntaxError("end_of_file_in_block_comment");
#ifndef __YAP_PROLOG__
	/* YAP does not support comment levels in original scanner */
case '*':
	if ( last == '/' )
		level++;
	break;
#endif
case '/':
	if ( last == '*' &&
			(--level == 0 || _PL_rd->strictness) )
	{ if ( cbuf )
	{ addUTF8Buffer(cbuf, EOS);
	if ( !add_comment(cbuf, pos, _PL_rd PASS_LD) )
	{ discardBuffer(cbuf);
	return FALSE;
	}
	discardBuffer(cbuf);
	}
	c = ' ';
	goto handle_c;
	}
	break;
}
if ( something_read )
	addToBuffer(c == '\n' ? c : ' ', _PL_rd);
last = c;
}
} else
{ set_start_line;
addToBuffer('/', _PL_rd);
if ( isSymbolW(c) )
{ while( c != EOF && isSymbolW(c) &&
		!(c == '`' && _PL_rd->backquoted_string) )
{ addToBuffer(c, _PL_rd);
c = getchr();
}
}
dotseen = FALSE;
goto handle_c;
}
case '%': if ( something_read )
	addToBuffer(' ', _PL_rd);
if ( _PL_rd->comments )
{ union {
	tmp_buffer ctmpbuf;
	buffer uctmpbuf;
} u;
Buffer cbuf;

if ( rb.stream->position )
{ pbuf = *rb.stream->position;
pbuf.charno--;
pbuf.linepos--;
pos = &pbuf;
} else
	pos = NULL;

initBuffer(&u.ctmpbuf);
cbuf = (Buffer)&u.uctmpbuf;
addUTF8Buffer(cbuf, '%');

for(;;)
{ while((c=getchr()) != EOF && c != '\n')
{ addUTF8Buffer(cbuf, c);
if ( something_read )		/* record positions */
	addToBuffer(' ', _PL_rd);
}
if ( c == '\n' )
{ int c2 = Speekcode(rb.stream);

if ( c2 == '%' )
{ if ( something_read )
{ addToBuffer(c, _PL_rd);
addToBuffer(' ', _PL_rd);
}
addUTF8Buffer(cbuf, c);
c = Sgetcode(rb.stream);
assert(c==c2);
addUTF8Buffer(cbuf, c);
continue;
}
}
break;
}
addUTF8Buffer(cbuf, EOS);
if ( !add_comment(cbuf, pos, _PL_rd PASS_LD) )
{ discardBuffer(cbuf);
return FALSE;
}
discardBuffer(cbuf);
} else
{ while((c=getchr()) != EOF && c != '\n')
{ if ( something_read )		/* record positions */
	addToBuffer(' ', _PL_rd);
}
}
goto handle_c;		/* is the newline */
case '\'': if ( rb.here > rb.base && isDigit(rb.here[-1]) )
{ cucharp bs = &rb.here[-1];

if ( bs > rb.base && isDigit(bs[-1]) )
	bs--;
if ( bs > rb.base && isSign(bs[-1]) )
	bs--;

if ( bs == rb.base || !PlIdContW(bs[-1]) )
{ int base;

if ( isSign(bs[0]) )
	bs++;
base = atoi((char*)bs);

if ( base <= 36 )
{ if ( base == 0 )			/* 0'<c> */
{ addToBuffer(c, _PL_rd);
{ if ( (c=getchr()) != EOF )
{ addToBuffer(c, _PL_rd);
if ( c == '\\' ) 		/* 0'\<c> */
{ if ( (c=getchr()) != EOF )
	addToBuffer(c, _PL_rd);
} else if ( c == '\'' ) 	/* 0'' */
{ if ( (c=getchr()) != EOF )
{ if ( c == '\'' )
	addToBuffer(c, _PL_rd);
else
	goto handle_c;
}
}
break;
}
rawSyntaxError("end_of_file");
}
} else
{ int c2 = Speekcode(rb.stream);

if ( c2 != EOF )
{ if ( digitValue(base, c2) >= 0 )
{ addToBuffer(c, _PL_rd);
c = Sgetcode(rb.stream);
addToBuffer(c, _PL_rd);
dotseen = FALSE;
break;
}
goto sqatom;
}
rawSyntaxError("end_of_file");
}
}
}
}

sqatom:
set_start_line;
if ( !raw_read_quoted(c, _PL_rd) )
	fail;
dotseen = FALSE;
break;
case '"':	set_start_line;
if ( !raw_read_quoted(c, _PL_rd) )
	fail;
dotseen = FALSE;
break;
case '.': addToBuffer(c, _PL_rd);
set_start_line;
dotseen++;
c = getchr();
if ( isSymbolW(c) )
{ while( c != EOF && isSymbolW(c) &&
		!(c == '`' && _PL_rd->backquoted_string) )
{ addToBuffer(c, _PL_rd);
c = getchr();
}
dotseen = FALSE;
}
goto handle_c;
case '`': if ( _PL_rd->backquoted_string )
{ set_start_line;
if ( !raw_read_quoted(c, _PL_rd) )
	fail;
dotseen = FALSE;
break;
}
/*FALLTHROUGH*/
default:	if ( c < 0xff )
{ switch(_PL_char_types[c])
{ case SP:
case CT:
	blank:
	if ( dotseen )
	{ if ( rb.here - rb.base == 1 )
		rawSyntaxError("end_of_clause");
	ensure_space(c);
	addToBuffer(EOS, _PL_rd);
	return rb.base;
	}
do
{ if ( something_read ) /* positions, \0 --> ' ' */
	addToBuffer(c ? c : ' ', _PL_rd);
else
	ensure_space(c);
c = getchr();
} while( c != EOF && PlBlankW(c) );
goto handle_c;
case SY:
	set_start_line;
	do
	{ addToBuffer(c, _PL_rd);
	c = getchr();
	if ( c == '`' && _PL_rd->backquoted_string )
		break;
	} while( c != EOF && c <= 0xff && isSymbol(c) );
	/* TBD: wide symbols? */
	dotseen = FALSE;
	goto handle_c;
case LC:
case UC:
	set_start_line;
	do
	{ addToBuffer(c, _PL_rd);
	c = getchr();
	} while( c != EOF && PlIdContW(c) );
	dotseen = FALSE;
	goto handle_c;
default:
	addToBuffer(c, _PL_rd);
	dotseen = FALSE;
	set_start_line;
}
} else			/* > 255 */
{ if ( PlIdStartW(c) )
{ set_start_line;
do
{ addToBuffer(c, _PL_rd);
c = getchr();
} while( c != EOF && PlIdContW(c) );
dotseen = FALSE;
goto handle_c;
} else if ( PlBlankW(c) )
{ goto blank;
} else
{ addToBuffer(c, _PL_rd);
dotseen = FALSE;
set_start_line;
}
}
}
}
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Raw reading returns a string in  UTF-8   notation  of the a Prolog term.
Comment inside the term is  replaced  by   spaces  or  newline to ensure
proper reconstruction of source locations. Comment   before  the term is
skipped.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static unsigned char *
raw_read(ReadData _PL_rd, unsigned char **endp ARG_LD)
{ unsigned char *s;

if ( (rb.stream->flags & SIO_ISATTY) && Sfileno(rb.stream) >= 0 )
{ ttybuf tab;

PushTty(rb.stream, &tab, TTY_SAVE);		/* make sure tty is sane */
PopTty(rb.stream, &ttytab, FALSE);
s = raw_read2(_PL_rd PASS_LD);
PopTty(rb.stream, &tab, TRUE);
} else
{ s = raw_read2(_PL_rd PASS_LD);
}

if ( endp )
	*endp = _PL_rd->_rb.here;

return s;
}

static void
callCommentHook(term_t comments, term_t tpos, term_t term)
{ GET_LD
	fid_t fid;
term_t av;

if ( (fid = PL_open_foreign_frame()) &&
		(av = PL_new_term_refs(3)) )
{ qid_t qid;

PL_put_term(av+0, comments);
PL_put_term(av+1, tpos);
PL_put_term(av+2, term);

if ( (qid = PL_open_query(NULL, PL_Q_NODEBUG|PL_Q_CATCH_EXCEPTION,
		(predicate_t)PredCommentHook, av)) )
{ term_t ex;

if ( !PL_next_solution(qid) && (ex=PL_exception(qid)) )
	printMessage(ATOM_error, PL_TERM, ex);

PL_close_query(qid);
}
PL_discard_foreign_frame(fid);
}
}



/********************************
 *       PROLOG CONNECTION       *
 *********************************/

static unsigned char *
backSkipUTF8(unsigned const char *start, unsigned const char *end, int *chr)
{ const unsigned char *s;

for(s=end-1 ; s>start && ( *s&0x80 ); s--)
	;
utf8_get_char((char*)s, chr);

return (unsigned char *)s;
}


static unsigned char *
backSkipBlanks(const unsigned char *start, const unsigned char *end)
{ const unsigned char *s;

for( ; end > start; end = s)
{ unsigned char *e;
int chr;

for(s=end-1 ; s>start && ISUTF8_CB(*s); s--)
	;
e = (unsigned char*)utf8_get_char((char*)s, &chr);
assert(e == end);
if ( !PlBlankW(chr) )
	return (unsigned char*)end;
}

return (unsigned char *)start;
}

static inline ucharp
skipSpaces(cucharp in)
{ int chr;
ucharp s;

for( ; *in; in=s)
{ s = utf8_get_uchar(in, &chr);

if ( !PlBlankW(chr) )
	return (ucharp)in;
}

return (ucharp)in;
}



word
pl_raw_read2(term_t from, term_t term)
{ GET_LD
	unsigned char *s, *e, *t2, *top;
read_data rd;
word rval;
IOSTREAM *in;
int chr;
PL_chars_t txt;

if ( !getTextInputStream(from, &in) )
	fail;

init_read_data(&rd, in PASS_LD);
if ( !(s = raw_read(&rd, &e PASS_LD)) )
{ rval = PL_raise_exception(rd.exception);
goto out;
}

/* strip the input from blanks */
top = backSkipBlanks(s, e-1);
t2 = backSkipUTF8(s, top, &chr);
if ( chr == '.' )
	top = backSkipBlanks(s, t2);
/* watch for "0' ." */
if ( top < e && top-2 >= s && top[-1] == '\'' && top[-2] == '0' )
	top++;
*top = EOS;
s = skipSpaces(s);

txt.text.t    = (char*)s;
txt.length    = top-s;
txt.storage   = PL_CHARS_HEAP;
txt.encoding  = ENC_UTF8;
txt.canonical = FALSE;

rval = PL_unify_text(term, 0, &txt, PL_ATOM);
 LD->read_varnames = rd.varnames;

out:
free_read_data(&rd);
if ( Sferror(in) )
	return streamStatus(in);
else
	PL_release_stream(in);

return rval;
}


static int
unify_read_term_position(term_t tpos ARG_LD)
{ if ( tpos && source_line_no > 0 )
{ return PL_unify_term(tpos,
		PL_FUNCTOR, FUNCTOR_stream_position4,
		PL_INT64, source_char_no,
		PL_INT, source_line_no,
		PL_INT, source_line_pos,
		PL_INT64, source_byte_no);
} else
{ return TRUE;
}
}

static const opt_spec read_clause_options[] =
{ { ATOM_variable_names,    OPT_TERM },
		{ ATOM_term_position,     OPT_TERM },
		{ ATOM_subterm_positions, OPT_TERM },
		{ ATOM_process_comment,   OPT_BOOL },
		{ ATOM_comments,          OPT_TERM },
		{ ATOM_syntax_errors,     OPT_ATOM },
		{ NULL_ATOM,              0 }
};


/** read_clause(+Stream:stream, -Clause:clause, +Options:list)

Like read_term/3, but uses current compiler options.

Options:
 * variable_names(-Names)
 * process_comment(+Boolean)
 * comments(-List)
 * syntax_errors(+Atom)
 * term_position(-Position)
 * subterm_positions(-Layout)
 */
static int
read_clause(IOSTREAM *s, term_t term, term_t options ARG_LD)
{
	read_data rd;
	int rval;
	fid_t fid;
	term_t tpos = 0;
	term_t comments = 0;
	term_t opt_comments = 0;
	int process_comment;
	atom_t syntax_errors = ATOM_dec10;

	{
		OPCODE ophook = PredCommentHook->OpcodeOfPred;
		if (ophook == UNDEF_OPCODE || ophook == FAIL_OPCODE)
			process_comment = FALSE;
		else
			process_comment = TRUE;
	}
	if ( !(fid=PL_open_foreign_frame()) )
		return FALSE;

	retry:
	init_read_data(&rd, s PASS_LD);

	if ( options &&
			!scan_options(options, 0, ATOM_read_option, read_clause_options,
					&rd.varnames,
					&tpos,
					&rd.subtpos,
					&process_comment,
					&opt_comments,
					&syntax_errors) )
	{ PL_close_foreign_frame(fid);
	return FALSE;
	}

	if ( opt_comments )
	{ comments = PL_new_term_ref();
	} else if ( process_comment )
	{ if ( !tpos )
		tpos = PL_new_term_ref();
	comments = PL_new_term_ref();
	}

	REGS_FROM_LD
	rd.module = Yap_GetModuleEntry( LOCAL_SourceModule );
	if ( comments )
		rd.comments = PL_copy_term_ref(comments);
	rd.on_error = syntax_errors;
	rd.singles = rd.styleCheck & SINGLETON_CHECK ? 1 : 0;
	if ( (rval=read_term(term, &rd PASS_LD)) &&
			(!tpos || (rval=unify_read_term_position(tpos PASS_LD))) )
	{
		PredEntry *ap;
                LD->read_varnames = rd.varnames;

		if (rd.singles) {
			// warning, singletons([X=_A],f(X,Y,Z), pos).
			printMessage(ATOM_warning,
					PL_FUNCTOR_CHARS, "singletons", 3,
					PL_TERM, rd.singles,
					PL_TERM, term,
					PL_TERM, tpos );
		}
		ap = Yap_PredFromClause( Yap_GetFromSlot(term)  PASS_REGS);
		if (rd.styleCheck & (DISCONTIGUOUS_STYLE|MULTIPLE_CHECK) && ap != NULL ) {
			if ( rd.styleCheck & (DISCONTIGUOUS_STYLE) && Yap_discontiguous( ap  PASS_REGS) ) {
				printMessage(ATOM_warning,
						PL_FUNCTOR_CHARS, "discontiguous", 2,
						PL_TERM, term,
						PL_TERM, tpos );
			}
			if (  rd.styleCheck & (MULTIPLE_CHECK) &&  Yap_multiple( ap  PASS_REGS) ) {
				printMessage(ATOM_warning,
						PL_FUNCTOR_CHARS, "multiple", 3,
						PL_TERM, term,
						PL_TERM, tpos,
						PL_ATOM, YAP_SWIAtomFromAtom(ap->src.OwnerFile) );
			}
		}
		if ( rd.comments &&
				(rval = PL_unify_nil(rd.comments)) )
		{ if ( opt_comments )
			rval = PL_unify(opt_comments, comments);
		else if ( !PL_get_nil(comments) )
			callCommentHook(comments, tpos, term);
		}
	} else
	{ if ( rd.has_exception && reportReadError(&rd) )
	{ PL_rewind_foreign_frame(fid);
	free_read_data(&rd);
	goto retry;
	}
	}
	free_read_data(&rd);

	return rval;
}


static
PRED_IMPL("read_clause", 3, read_clause, 0)
{ PRED_LD
	int rc;
IOSTREAM *s;

if ( !getTextInputStream(A1, &s) )
	return FALSE;
rc = read_clause(s, A2, A3 PASS_LD);
if ( Sferror(s) )
	return streamStatus(s);
else
	PL_release_stream(s);

return rc;
}


word
pl_raw_read(term_t term)
{ return pl_raw_read2(0, term);
}


static const opt_spec read_term_options[] =
{ { ATOM_variable_names,    OPT_TERM },
		{ ATOM_variables,         OPT_TERM },
		{ ATOM_singletons,        OPT_TERM },
		{ ATOM_term_position,     OPT_TERM },
  //  		{ ATOM_subterm_positions, OPT_TERM },
		{ ATOM_character_escapes, OPT_BOOL },
		{ ATOM_double_quotes,	    OPT_ATOM },
		{ ATOM_module,	    OPT_ATOM },
		{ ATOM_syntax_errors,     OPT_ATOM },
		{ ATOM_backquoted_string, OPT_BOOL },
		{ ATOM_comments,	    OPT_TERM },
		{ ATOM_process_comment,   OPT_BOOL },
#ifdef O_QUASIQUOTATIONS
		{ ATOM_quasi_quotations,  OPT_TERM },
#endif
		{ ATOM_cycles,	    OPT_BOOL },
		{ NULL_ATOM,		    0 }
};


static foreign_t
read_term_from_stream(IOSTREAM *s, term_t term, term_t options ARG_LD)
{ term_t tpos = 0;
term_t comments = 0;
term_t opt_comments = 0;
int process_comment;
int rval;
atom_t w;
read_data rd;
int charescapes = -1;
atom_t dq = NULL_ATOM;
atom_t mname = NULL_ATOM;
fid_t fid = PL_open_foreign_frame();

if (!fid)
	return FALSE;
retry:
 init_read_data(&rd, s PASS_LD);

if ( !scan_options(options, 0, ATOM_read_option, read_term_options,
		&rd.varnames,
		&rd.variables,
		&rd.singles,
		&tpos,
		   //		&rd.subtpos,
		&charescapes,
		&dq,
		&mname,
		&rd.on_error,
		&rd.backquoted_string,
		&opt_comments,
		&process_comment,
#ifdef O_QUASIQUOTATIONS
		&rd.quasi_quotations,
#endif
		&rd.cycles) ) {
	PL_discard_foreign_frame(fid);
	free_read_data(&rd);
	return FALSE;
}

// yap specific, do not call process comment if undefined
if (process_comment) {
	OPCODE ophook = PredCommentHook->OpcodeOfPred;
	if (ophook == UNDEF_OPCODE || ophook == FAIL_OPCODE)
		process_comment = FALSE;
}

if ( opt_comments )
{ comments = PL_new_term_ref();
} else if ( process_comment )
{ if ( !tpos )
	tpos = PL_new_term_ref();
comments = PL_new_term_ref();
}

if ( mname )
{ rd.module = lookupModule(mname);
rd.flags  = rd.module->flags;
}

if ( charescapes != -1 )
{ if ( charescapes )
	set(&rd, M_CHARESCAPE);
else
	clear(&rd, M_CHARESCAPE);
}
if ( dq )
{ if ( !setDoubleQuotes(dq, &rd.flags) )
	return FALSE;
}
if ( rd.singles && PL_get_atom(rd.singles, &w) && w == ATOM_warning)
	rd.singles = 1;

if ( comments )
	rd.comments = PL_copy_term_ref(comments);

rval = read_term(term, &rd PASS_LD);
if ( Sferror(s) ) {
	free_read_data(&rd);
	return FALSE;
}
 LD->read_varnames = rd.varnames;
#ifdef O_QUASIQUOTATIONS
 if ( rval )
	rval = parse_quasi_quotations(&rd PASS_LD);
#endif
if ( rval )
{ if ( tpos )
	rval = unify_read_term_position(tpos PASS_LD);
if (rval) {
	if ( opt_comments )
		rval = PL_unify(opt_comments, comments);
	else if (comments && !PL_get_nil(comments) )
		callCommentHook(comments, tpos, term);
}
} else {
	if ( rd.has_exception && reportReadError(&rd) )
	{ PL_rewind_foreign_frame(fid);
	free_read_data(&rd);
	goto retry;
	}
}
free_read_data(&rd);

return rval;
}


/** @pred  read_term(+ _Stream_,- _T_,+ _Options_) is iso

Reads term  _T_ from stream  _Stream_ with execution controlled by the
same options as read_term/2.


*/
static
PRED_IMPL("read_term", 3, read_term, PL_FA_ISO)
{ PRED_LD
	IOSTREAM *s;

if ( getTextInputStream(A1, &s) )
{ if ( read_term_from_stream(s, A2, A3 PASS_LD) )
	return PL_release_stream(s);
if ( Sferror(s) )
	return streamStatus(s);
PL_release_stream(s);
return FALSE;
}

return FALSE;
}

/** read_term(-Term, +Options) is det.
 */


/** @pred read_term(- _T_,+ _Options_) is iso


Reads term  _T_ from the current input stream with execution
controlled by the following options:

+ comments(- _Comments_)

    Unify _Comments_ with a list of string terms including comments before
and within the term.

+ module( + _Module_)

    Read term using _Module_ as source module.

+ quasi_quotations(-List)

    Unify _List_ with the quasi-quotations present in the term.

+ term_position(- _Position_)

    Unify  _Position_ with a term describing the position of the stream
at the start of parse. Use stream_position_data/3 to obtain extra
information.

+ singletons(- _Names_)

    Unify  _Names_ with a list of the form  _Name=Var_, where
 _Name_ is the name of a non-anonymous singleton variable in the
original term, and `Var` is the variable's representation in
YAP.
The variables occur in left-to-right traversal order.

+ syntax_errors(+ _Val_)

    Control action to be taken after syntax errors. See yap_flag/2
for detailed information.

+ variables(- _Names_)

     Unify  _Names_ with a list of the form  _Name=Var_, where  _Name_ is
the name of a non-anonymous variable in the original term, and  _Var_
is the variable's representation in YAP.
The variables occur in left-to-right traversal order.


*/
static
PRED_IMPL("read_term", 2, read_term, PL_FA_ISO)
{ PRED_LD
	IOSTREAM *s;

if ( getTextInputStream(0, &s) )
{ if ( read_term_from_stream(s, A1, A2 PASS_LD) )
	return PL_release_stream(s);
if ( Sferror(s) )
	return streamStatus(s);
PL_release_stream(s);
return FALSE;
}

return FALSE;
}


/*******************************
 *	   TERM <->ATOM		*
 *******************************/

static int
atom_to_term(term_t atom, term_t term, term_t bindings)
{ GET_LD
  PL_chars_t txt;

if ( !bindings && PL_is_variable(atom) ) /* term_to_atom(+, -) */
  { char buf[1024];
  size_t bufsize = sizeof(buf);
  int rval;
  char *s = buf;
  IOSTREAM *stream;
  PL_chars_t txt;

  stream = Sopenmem(&s, &bufsize, "w");
  stream->encoding = ENC_UTF8;
  PL_write_term(stream, term, 1200, PL_WRT_QUOTED);
  Sflush(stream);

  txt.text.t = s;
  txt.length = bufsize;
  txt.storage = PL_CHARS_HEAP;
  txt.encoding = ENC_UTF8;
  txt.canonical = FALSE;
  rval = PL_unify_text(atom, 0, &txt, PL_ATOM);

  Sclose(stream);
  if ( s != buf )
    Sfree(s);

  return rval;
  }

if ( PL_get_text(atom, &txt, CVT_ALL|CVT_EXCEPTION) )
  { GET_LD
    read_data rd;
  int rval;
  IOSTREAM *stream;
  source_location oldsrc = LD->read_source;

  stream = Sopen_text(&txt, "r");

  init_read_data(&rd, stream PASS_LD);
  if ( bindings && (PL_is_variable(bindings) || PL_is_list(bindings)) )
    rd.varnames = bindings;
  else if ( bindings )
    return PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_list, bindings);

  if ( !(rval = read_term(term, &rd PASS_LD)) && rd.has_exception )
    rval = PL_raise_exception(rd.exception);
  free_read_data(&rd);
  Sclose(stream);
  LD->read_source = oldsrc;

  //   getchar();
  return rval;
  }

fail;
}

Term
Yap_StringToTerm(const char *s, size_t len, term_t bindings)
{ GET_LD;
  read_data rd;
  int rval;
  IOSTREAM *stream;
  source_location oldsrc = LD->read_source;

  stream = Sopen_string(0, (char *)s, strlen( s ),  "r");

init_read_data(&rd, stream PASS_LD);
rd.varnames = bindings;
term_t tt = Yap_NewSlots(1);

if ( !(rval = read_term(tt, &rd PASS_LD)) && rd.has_exception ) {
  rval = PL_raise_exception(rd.exception);
  return 0L;
}
free_read_data(&rd);
Sclose(stream);
LD->read_source = oldsrc;

//   getchar();
return Yap_GetFromSlot( tt);
}

/** @pred atom_to_term(+ _Atom_, - _Term_, - _Bindings_)


Use  _Atom_ as input to read_term/2 using the option `variable_names` and return the read term in  _Term_ and the variable bindings in  _Bindings_.  _Bindings_ is a list of `Name = Var` couples, thus providing access to the actual variable names. See also read_term/2. If Atom has no valid syntax, a syntax_error exception is raised.


*/
static
PRED_IMPL("atom_to_term", 3, atom_to_term, 0)
{ return atom_to_term(A1, A2, A3);
}


static
PRED_IMPL("term_to_atom", 2, term_to_atom, 0)
{ return atom_to_term(A2, A1, 0);
}

static
PRED_IMPL("$context_variables", 1, context_variables, 0)
{   CACHE_REGS
    if ( LOCAL_VarNames == (CELL)0 )
      return Yap_unify( TermNil, ARG1);
    return Yap_unify( LOCAL_VarNames, ARG1);
}

static
PRED_IMPL("$set_source", 2, set_source, 0)
{
  GET_LD
  atom_t at;
  term_t a = PL_new_term_ref();

  if (!PL_get_atom(A1, &at))
    return FALSE;
  source_file_name = at;
  if (!PL_get_arg(1, A2, a) || !PL_get_int64(a, &source_char_no) ||
      !PL_get_arg(2, A2, a) || !PL_get_long(a, &source_line_no) ||
      !PL_get_arg(3, A2, a) || !PL_get_long(a, &source_line_pos) ||
      !PL_get_arg(4, A2, a) || !PL_get_int64(a, &source_byte_no) ) {
    return FALSE;
  }
  return TRUE;
}

int
PL_chars_to_term(const char *s, term_t t)
{ GET_LD
	read_data rd;
  int rval;
IOSTREAM *stream = Sopen_string(NULL, (char *)s, -1, "r");
source_location oldsrc = LD->read_source;

init_read_data(&rd, stream PASS_LD);
PL_put_variable(t);
if ( !(rval = read_term(t, &rd PASS_LD)) && rd.has_exception )
	PL_put_term(t, rd.exception);
 LOCAL_VarNames = rd.varnames;
   free_read_data(&rd);
Sclose(stream);
LD->read_source = oldsrc;

return rval;
}

/*******************************
 *      PUBLISH PREDICATES	*
 *******************************/

BeginPredDefs(read)
PRED_DEF("read_term",		  3, read_term,		  PL_FA_ISO)
PRED_DEF("read_term",		  2, read_term,		  PL_FA_ISO)
PRED_DEF("read_clause",         3, read_clause,         0)
PRED_DEF("atom_to_term", 3, atom_to_term, 0)
PRED_DEF("term_to_atom", 2, term_to_atom, 0)
PRED_DEF("$context_variables", 1, context_variables, 0)
PRED_DEF("$set_source",  2, set_source, 0)
#ifdef O_QUASIQUOTATIONS
PRED_DEF("$qq_open",            2, qq_open,             0)
#endif
EndPredDefs

//! @}