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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2009 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* token stream routines
*/
#include <ast.h>
#include <tok.h>
#define FLG_RESTORE 01 /* restore string on close */
#define FLG_NEWLINE 02 /* return newline token next */
typedef struct Tok_s /* token stream state */
{
union
{
char* end; /* end ('\0') of last token */
struct Tok_s* nxt; /* next in free list */
} ptr;
char chr; /* replace *end with this */
char flg; /* FLG_* */
} Tok_t;
static Tok_t* freelist;
/*
* open a new token stream on s
* if f==0 then string is not restored
*/
char*
tokopen(register char* s, int f)
{
register Tok_t* p;
if (p = freelist)
freelist = freelist->ptr.nxt;
else if (!(p = newof(0, Tok_t, 1, 0)))
return 0;
p->chr = *(p->ptr.end = s);
p->flg = f ? FLG_RESTORE : 0;
return (char*)p;
}
/*
* close a token stream
* restore the string to its original state
*/
void
tokclose(char* u)
{
register Tok_t* p = (Tok_t*)u;
if (p->flg == FLG_RESTORE && *p->ptr.end != p->chr)
*p->ptr.end = p->chr;
p->ptr.nxt = freelist;
freelist = p;
}
/*
* return next space separated token
* "\n" is returned as a token
* 0 returned when no tokens remain
* "..." and '...' quotes are honored with \ escapes
*/
char*
tokread(char* u)
{
register Tok_t* p = (Tok_t*)u;
register char* s;
register char* r;
register int q;
register int c;
/*
* restore string on each call
*/
if (!p->chr)
return 0;
s = p->ptr.end;
switch (p->flg)
{
case FLG_NEWLINE:
p->flg = 0;
return "\n";
case FLG_RESTORE:
if (*s != p->chr)
*s = p->chr;
break;
default:
if (!*s)
s++;
break;
}
/*
* skip leading space
*/
while (*s == ' ' || *s == '\t')
s++;
if (!*s)
{
p->ptr.end = s;
p->chr = 0;
return 0;
}
/*
* find the end of this token
*/
r = s;
q = 0;
for (;;)
switch (c = *r++)
{
case '\n':
if (!q)
{
if (s == (r - 1))
{
if (!p->flg)
{
p->ptr.end = r;
return "\n";
}
r++;
}
else if (!p->flg)
p->flg = FLG_NEWLINE;
}
/*FALLTHROUGH*/
case ' ':
case '\t':
if (q)
break;
/*FALLTHROUGH*/
case 0:
if (s == --r)
{
p->ptr.end = r;
p->chr = 0;
}
else
{
p->chr = *(p->ptr.end = r);
if (*r)
*r = 0;
}
return s;
case '\\':
if (*r)
r++;
break;
case '"':
case '\'':
if (c == q)
q = 0;
else if (!q)
q = c;
break;
}
}
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