src/common/caldefn.c

/* Copyright (c) 1986 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  Store variable definitions.
 *
 *  7/1/85  Greg Ward
 *
 *  11/11/85  Added conditional compiles (OUTCHAN) for control output.
 *
 *  4/2/86  Added conditional compiles for function definitions (FUNCTION).
 *
 *  1/15/88  Added clock for caching of variable values.
 *
 *  11/16/88  Added VARDEF structure for hard linking.
 *
 *  5/31/90  Added conditional compile (REDEFW) for redefinition warning.
 *
 *  4/23/91  Added ':' defines for constant expressions (RCONST)
 */

#include  <stdio.h>

#include  <ctype.h>

#include  "calcomp.h"

#ifndef  NHASH
#define  NHASH          521             /* hash size (a prime!) */
#endif

#define  newnode()      (EPNODE *)ecalloc(1, sizeof(EPNODE))

extern char  *ecalloc(), *savestr();

static double  dvalue();

long  eclock = -1;                      /* value storage timer */

static VARDEF  *hashtbl[NHASH];         /* definition list */
static int  htndx;                      /* index for */         
static VARDEF  *htpos;                  /* ...dfirst() and */
#ifdef  OUTCHAN
static EPNODE  *ochpos;                 /* ...dnext */
static EPNODE  *outchan;
#endif

#ifdef  FUNCTION
EPNODE  *curfunc;
#define  dname(ep)      ((ep)->v.kid->type == SYM ? \
                        (ep)->v.kid->v.name : \
                        (ep)->v.kid->v.kid->v.name)
#else
#define  dname(ep)      ((ep)->v.kid->v.name)
#endif


fcompile(fname)                 /* get definitions from a file */
char  *fname;
{
    FILE  *fp;

    if (fname == NULL)
        fp = stdin;
    else if ((fp = fopen(fname, "r")) == NULL) {
        eputs(fname);
        eputs(": cannot open\n");
        quit(1);
    }
    initfile(fp, fname, 0);
    while (nextc != EOF)
        loaddefn();
    if (fname != NULL)
        fclose(fp);
}


scompile(str, fn, ln)           /* get definitions from a string */
char  *str;
char  *fn;
int  ln;
{
    initstr(str, fn, ln);
    while (nextc != EOF)
        loaddefn();
}


double
varvalue(vname)                 /* return a variable's value */
char  *vname;
{
    return(dvalue(vname, dlookup(vname)));
}


double
evariable(ep)                   /* evaluate a variable */
EPNODE  *ep;
{
    register VARDEF  *dp = ep->v.ln;

    return(dvalue(dp->name, dp->def));
}


varset(vname, assign, val)      /* set a variable's value */
char  *vname;
int  assign;
double  val;
{
    register EPNODE  *ep1, *ep2;
                                        /* check for quick set */
    if ((ep1 = dlookup(vname)) != NULL && ep1->v.kid->type == SYM) {
        ep2 = ep1->v.kid->sibling;
        if (ep2->type == NUM) {
            ep2->v.num = val;
            ep1->type = assign;
            return;
        }
    }
                                        /* hand build definition */
    ep1 = newnode();
    ep1->type = assign;
    ep2 = newnode();
    ep2->type = SYM;
    ep2->v.name = savestr(vname);
    addekid(ep1, ep2);
    ep2 = newnode();
    ep2->type = NUM;
    ep2->v.num = val;
    addekid(ep1, ep2);
    dremove(vname);
    dpush(ep1);
}


dclear(name)                    /* delete variable definitions of name */
char  *name;
{
    register EPNODE  *ep;

    while ((ep = dpop(name)) != NULL) {
        if (ep->type == ':') {
            dpush(ep);          /* don't clear constants */
            return;
        }
        epfree(ep);
    }
}


dremove(name)                   /* delete all definitions of name */
char  *name;
{
    register EPNODE  *ep;

    while ((ep = dpop(name)) != NULL)
        epfree(ep);
}


vardefined(name)        /* return non-zero if variable defined */
char  *name;
{
    register EPNODE  *dp;

    return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
}


#ifdef  OUTCHAN
chanout(cs)                     /* set output channels */
int  (*cs)();
{
    register EPNODE  *ep;

    for (ep = outchan; ep != NULL; ep = ep->sibling)
        (*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));

}
#endif


dclearall()                     /* clear all definitions */
{
    register int  i;
    register VARDEF  *vp;
    register EPNODE  *ep;

    for (i = 0; i < NHASH; i++)
        for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
            dremove(vp->name);
#ifdef  OUTCHAN
    for (ep = outchan; ep != NULL; ep = ep->sibling)
        epfree(ep);
    outchan = NULL;
#endif
}


EPNODE *
dlookup(name)                   /* look up a definition */
char  *name;
{
    register VARDEF  *vp;
    
    if ((vp = varlookup(name)) == NULL)
        return(NULL);
    return(vp->def);
}


VARDEF *
varlookup(name)                 /* look up a variable */
char  *name;
{
    register VARDEF  *vp;
    
    for (vp = hashtbl[hash(name)]; vp != NULL; vp = vp->next)
        if (!strcmp(vp->name, name))
            return(vp);
    return(NULL);
}


VARDEF *
varinsert(name)                 /* get a link to a variable */
char  *name;
{
    register VARDEF  *vp;
    int  hv;
    
    hv = hash(name);
    for (vp = hashtbl[hv]; vp != NULL; vp = vp->next)
        if (!strcmp(vp->name, name)) {
            vp->nlinks++;
            return(vp);
        }
    vp = (VARDEF *)emalloc(sizeof(VARDEF));
    vp->name = savestr(name);
    vp->nlinks = 1;
    vp->def = NULL;
    vp->lib = NULL;
    vp->next = hashtbl[hv];
    hashtbl[hv] = vp;
    return(vp);
}


varfree(ln)                             /* release link to variable */
register VARDEF  *ln;
{
    register VARDEF  *vp;
    int  hv;

    if (--ln->nlinks > 0)
        return;                         /* still active */

    hv = hash(ln->name);
    vp = hashtbl[hv];
    if (vp == ln)
        hashtbl[hv] = vp->next;
    else {
        while (vp->next != ln)          /* must be in list */
                vp = vp->next;
        vp->next = ln->next;
    }
    freestr(ln->name);
    efree((char *)ln);
}


EPNODE *
dfirst()                        /* return pointer to first definition */
{
    htndx = 0;
    htpos = NULL;
#ifdef  OUTCHAN
    ochpos = outchan;
#endif
    return(dnext());
}


EPNODE *
dnext()                         /* return pointer to next definition */
{
    register EPNODE  *ep;

    while (htndx < NHASH) {
        if (htpos == NULL)
                htpos = hashtbl[htndx++];
        while (htpos != NULL) {
            ep = htpos->def;
            htpos = htpos->next;
            if (ep != NULL)
                return(ep);
        }
    }
#ifdef  OUTCHAN
    if ((ep = ochpos) != NULL)
        ochpos = ep->sibling;
    return(ep);
#else
    return(NULL);
#endif
}


EPNODE *
dpop(name)                      /* pop a definition */
char  *name;
{
    register VARDEF  *vp;
    register EPNODE  *dp;
    
    if ((vp = varlookup(name)) == NULL || vp->def == NULL)
        return(NULL);
    dp = vp->def;
    vp->def = dp->sibling;
    varfree(vp);
    return(dp);
}


dpush(ep)                       /* push on a definition */
register EPNODE  *ep;
{
    register VARDEF  *vp;

    vp = varinsert(dname(ep));
    ep->sibling = vp->def;
    vp->def = ep;
}


#ifdef  OUTCHAN
addchan(sp)                     /* add an output channel assignment */
EPNODE  *sp;
{
    int  ch = sp->v.kid->v.chan;
    register EPNODE  *ep, *epl;

    for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
        if (ep->v.kid->v.chan >= ch) {
            if (epl != NULL)
                epl->sibling = sp;
            else
                outchan = sp;
            if (ep->v.kid->v.chan > ch)
                sp->sibling = ep;
            else {
                sp->sibling = ep->sibling;
                epfree(ep);
            }
            return;
        }
    if (epl != NULL)
        epl->sibling = sp;
    else
        outchan = sp;
    sp->sibling = NULL;

}
#endif


loaddefn()                      /* load next definition */
{
    register EPNODE  *ep;

    if (nextc == ';') {         /* empty statement */
        scan();
        return;
    }
#ifdef  OUTCHAN
    if (nextc == '$') {         /* channel assignment */
        ep = getchan();
        addchan(ep);
    } else
#endif
    {                           /* ordinary definition */
        ep = getdefn();
#ifdef  REDEFW
        if (dlookup(dname(ep)) != NULL) {
            dclear(dname(ep));
            wputs(dname(ep));
            if (dlookup(dname(ep)) == NULL)
                wputs(": redefined\n");
            else
                wputs(": redefined constant expression\n");
        }
#ifdef  FUNCTION
        else if (ep->v.kid->type == FUNC &&
                        liblookup(ep->v.kid->v.kid->v.name) != NULL) {
            wputs(ep->v.kid->v.kid->v.name);
            wputs(": redefined library function\n");
        }
#endif
#else
        dclear(dname(ep));
#endif
        dpush(ep);
    }
    if (nextc != EOF) {
        if (nextc != ';')
            syntax("';' expected");
        scan();
    }
}


EPNODE *
getdefn()                       /* A -> SYM = E1 */
                                /*      SYM : E1 */
                                /*      FUNC(SYM,..) = E1 */
                                /*      FUNC(SYM,..) : E1 */
{
    register EPNODE  *ep1, *ep2;

    if (!isalpha(nextc))
        syntax("illegal variable name");

    ep1 = newnode();
    ep1->type = SYM;
    ep1->v.name = savestr(getname());

#ifdef  FUNCTION
    if (nextc == '(') {
        ep2 = newnode();
        ep2->type = FUNC;
        addekid(ep2, ep1);
        ep1 = ep2;
        do {
            scan();
            if (!isalpha(nextc))
                syntax("illegal variable name");
            ep2 = newnode();
            ep2->type = SYM;
            ep2->v.name = savestr(getname());
            addekid(ep1, ep2);
        } while (nextc == ',');
        if (nextc != ')')
            syntax("')' expected");
        scan();
        curfunc = ep1;
    } else
        curfunc = NULL;
#endif

    if (nextc != '=' && nextc != ':')
        syntax("'=' or ':' expected");

    ep2 = newnode();
    ep2->type = nextc;
    scan();
    addekid(ep2, ep1);
#ifdef  RCONST
    if (
#ifdef  FUNCTION
            ep1->type == SYM &&
#endif
            ep2->type == ':')
        addekid(ep2, rconst(getE1()));
    else
#endif
    addekid(ep2, getE1());

    if (
#ifdef  FUNCTION
            ep1->type == SYM &&
#endif
            ep1->sibling->type != NUM) {
        ep1 = newnode();
        ep1->type = TICK;
        ep1->v.tick = -1;
        addekid(ep2, ep1);
        ep1 = newnode();
        ep1->type = NUM;
        addekid(ep2, ep1);
    }

    return(ep2);
}


#ifdef  OUTCHAN
EPNODE *
getchan()                       /* A -> $N = E1 */
{
    register EPNODE  *ep1, *ep2;

    if (nextc != '$')
        syntax("missing '$'");
    scan();

    ep1 = newnode();
    ep1->type = CHAN;
    ep1->v.chan = getinum();

    if (nextc != '=')
        syntax("'=' expected");
    scan();

    ep2 = newnode();
    ep2->type = '=';
    addekid(ep2, ep1);
    addekid(ep2, getE1());

    return(ep2);
}
#endif


/*
 *  The following routines are for internal use only:
 */


static double
dvalue(name, d)                 /* evaluate a variable */
char  *name;
EPNODE  *d;
{
    register EPNODE  *ep1, *ep2;
    
    if (d == NULL || d->v.kid->type != SYM) {
        eputs(name);
        eputs(": undefined variable\n");
        quit(1);
    }
    ep1 = d->v.kid->sibling;                    /* get expression */
    if (ep1->type == NUM)
        return(ep1->v.num);                     /* return if number */
    ep2 = ep1->sibling;                         /* check time */
    if (ep2->v.tick < 0 || ep2->v.tick < eclock) {
        ep2->v.tick = d->type == ':' ? 1L<<30 : eclock;
        ep2 = ep2->sibling;
        ep2->v.num = evalue(ep1);               /* needs new value */
    } else
        ep2 = ep2->sibling;                     /* else reuse old value */

    return(ep2->v.num);
}


static int
hash(s)                         /* hash a string */
register char  *s;
{
    register int  rval = 0;

    while (*s)
        rval += *s++;
    
    return(rval % NHASH);
}
Revision:	1.8
Committed:	Tue Apr 23 12:59:33 1991 UTC (33 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.7:	+52 -12 lines
Log Message:	added ':' definitions for constant expressions
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1986 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Store variable definitions.
9			*
10			* 7/1/85 Greg Ward
11			*
12			* 11/11/85 Added conditional compiles (OUTCHAN) for control output.
13			*
14			* 4/2/86 Added conditional compiles for function definitions (FUNCTION).
15			*
16			* 1/15/88 Added clock for caching of variable values.
17			*
18			* 11/16/88 Added VARDEF structure for hard linking.
19	greg	1.2	*
20			* 5/31/90 Added conditional compile (REDEFW) for redefinition warning.
21	greg	1.8	*
22			* 4/23/91 Added ':' defines for constant expressions (RCONST)
23	greg	1.1	*/
24
25			#include <stdio.h>
26
27			#include <ctype.h>
28
29			#include "calcomp.h"
30
31			#ifndef NHASH
32			#define NHASH 521 /* hash size (a prime!) */
33			#endif
34
35			#define newnode() (EPNODE *)ecalloc(1, sizeof(EPNODE))
36
37			extern char ecalloc(), savestr();
38
39	greg	1.3	static double dvalue();
40	greg	1.1
41			long eclock = -1; /* value storage timer */
42
43			static VARDEF hashtbl[NHASH]; / definition list */
44			static int htndx; /* index for */
45			static VARDEF htpos; / ...dfirst() and */
46			#ifdef OUTCHAN
47			static EPNODE ochpos; / ...dnext */
48			static EPNODE *outchan;
49			#endif
50
51			#ifdef FUNCTION
52			EPNODE *curfunc;
53			#define dname(ep) ((ep)->v.kid->type == SYM ? \
54			(ep)->v.kid->v.name : \
55			(ep)->v.kid->v.kid->v.name)
56			#else
57			#define dname(ep) ((ep)->v.kid->v.name)
58			#endif
59
60
61			fcompile(fname) /* get definitions from a file */
62			char *fname;
63			{
64			FILE *fp;
65
66			if (fname == NULL)
67			fp = stdin;
68			else if ((fp = fopen(fname, "r")) == NULL) {
69			eputs(fname);
70			eputs(": cannot open\n");
71			quit(1);
72			}
73	greg	1.4	initfile(fp, fname, 0);
74	greg	1.1	while (nextc != EOF)
75			loaddefn();
76			if (fname != NULL)
77			fclose(fp);
78			}
79
80
81	greg	1.4	scompile(str, fn, ln) /* get definitions from a string */
82	greg	1.1	char *str;
83	greg	1.4	char *fn;
84			int ln;
85	greg	1.1	{
86	greg	1.4	initstr(str, fn, ln);
87	greg	1.1	while (nextc != EOF)
88			loaddefn();
89			}
90
91
92			double
93			varvalue(vname) /* return a variable's value */
94			char *vname;
95			{
96			return(dvalue(vname, dlookup(vname)));
97			}
98
99
100			double
101			evariable(ep) /* evaluate a variable */
102			EPNODE *ep;
103			{
104			register VARDEF *dp = ep->v.ln;
105
106			return(dvalue(dp->name, dp->def));
107			}
108
109
110	greg	1.8	varset(vname, assign, val) /* set a variable's value */
111	greg	1.1	char *vname;
112	greg	1.8	int assign;
113	greg	1.1	double val;
114			{
115			register EPNODE ep1, ep2;
116			/* check for quick set */
117			if ((ep1 = dlookup(vname)) != NULL && ep1->v.kid->type == SYM) {
118			ep2 = ep1->v.kid->sibling;
119			if (ep2->type == NUM) {
120			ep2->v.num = val;
121	greg	1.8	ep1->type = assign;
122	greg	1.1	return;
123			}
124			}
125			/* hand build definition */
126			ep1 = newnode();
127	greg	1.8	ep1->type = assign;
128	greg	1.1	ep2 = newnode();
129			ep2->type = SYM;
130			ep2->v.name = savestr(vname);
131			addekid(ep1, ep2);
132			ep2 = newnode();
133			ep2->type = NUM;
134			ep2->v.num = val;
135			addekid(ep1, ep2);
136	greg	1.8	dremove(vname);
137	greg	1.1	dpush(ep1);
138			}
139
140
141	greg	1.8	dclear(name) /* delete variable definitions of name */
142	greg	1.1	char *name;
143			{
144			register EPNODE *ep;
145
146	greg	1.8	while ((ep = dpop(name)) != NULL) {
147			if (ep->type == ':') {
148			dpush(ep); /* don't clear constants */
149			return;
150			}
151			epfree(ep);
152			}
153			}
154
155
156			dremove(name) /* delete all definitions of name */
157			char *name;
158			{
159			register EPNODE *ep;
160
161	greg	1.1	while ((ep = dpop(name)) != NULL)
162			epfree(ep);
163			}
164
165
166			vardefined(name) /* return non-zero if variable defined */
167			char *name;
168			{
169			register EPNODE *dp;
170
171			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
172			}
173
174
175			#ifdef OUTCHAN
176	greg	1.6	chanout(cs) /* set output channels */
177			int (*cs)();
178	greg	1.1	{
179			register EPNODE *ep;
180
181			for (ep = outchan; ep != NULL; ep = ep->sibling)
182	greg	1.6	(*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
183	greg	1.1
184			}
185			#endif
186
187
188			dclearall() /* clear all definitions */
189			{
190			register int i;
191			register VARDEF *vp;
192			register EPNODE *ep;
193
194			for (i = 0; i < NHASH; i++)
195			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
196	greg	1.8	dremove(vp->name);
197	greg	1.1	#ifdef OUTCHAN
198			for (ep = outchan; ep != NULL; ep = ep->sibling)
199			epfree(ep);
200			outchan = NULL;
201			#endif
202			}
203
204
205			EPNODE *
206			dlookup(name) /* look up a definition */
207			char *name;
208			{
209			register VARDEF *vp;
210
211			if ((vp = varlookup(name)) == NULL)
212			return(NULL);
213			return(vp->def);
214			}
215
216
217			VARDEF *
218			varlookup(name) /* look up a variable */
219			char *name;
220			{
221			register VARDEF *vp;
222
223			for (vp = hashtbl[hash(name)]; vp != NULL; vp = vp->next)
224			if (!strcmp(vp->name, name))
225			return(vp);
226			return(NULL);
227			}
228
229
230			VARDEF *
231			varinsert(name) /* get a link to a variable */
232			char *name;
233			{
234			register VARDEF *vp;
235			int hv;
236
237			hv = hash(name);
238			for (vp = hashtbl[hv]; vp != NULL; vp = vp->next)
239			if (!strcmp(vp->name, name)) {
240			vp->nlinks++;
241			return(vp);
242			}
243			vp = (VARDEF *)emalloc(sizeof(VARDEF));
244			vp->name = savestr(name);
245			vp->nlinks = 1;
246			vp->def = NULL;
247			vp->lib = NULL;
248			vp->next = hashtbl[hv];
249			hashtbl[hv] = vp;
250			return(vp);
251			}
252
253
254			varfree(ln) /* release link to variable */
255			register VARDEF *ln;
256			{
257			register VARDEF *vp;
258			int hv;
259
260			if (--ln->nlinks > 0)
261			return; /* still active */
262
263			hv = hash(ln->name);
264			vp = hashtbl[hv];
265			if (vp == ln)
266			hashtbl[hv] = vp->next;
267			else {
268			while (vp->next != ln) /* must be in list */
269			vp = vp->next;
270			vp->next = ln->next;
271			}
272			freestr(ln->name);
273			efree((char *)ln);
274			}
275
276
277			EPNODE *
278			dfirst() /* return pointer to first definition */
279			{
280			htndx = 0;
281			htpos = NULL;
282			#ifdef OUTCHAN
283			ochpos = outchan;
284			#endif
285			return(dnext());
286			}
287
288
289			EPNODE *
290			dnext() /* return pointer to next definition */
291			{
292			register EPNODE *ep;
293
294			while (htndx < NHASH) {
295			if (htpos == NULL)
296			htpos = hashtbl[htndx++];
297			while (htpos != NULL) {
298			ep = htpos->def;
299			htpos = htpos->next;
300			if (ep != NULL)
301			return(ep);
302			}
303			}
304			#ifdef OUTCHAN
305			if ((ep = ochpos) != NULL)
306			ochpos = ep->sibling;
307			return(ep);
308			#else
309			return(NULL);
310			#endif
311			}
312
313
314			EPNODE *
315			dpop(name) /* pop a definition */
316			char *name;
317			{
318			register VARDEF *vp;
319			register EPNODE *dp;
320
321			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
322			return(NULL);
323			dp = vp->def;
324			vp->def = dp->sibling;
325			varfree(vp);
326			return(dp);
327			}
328
329
330			dpush(ep) /* push on a definition */
331			register EPNODE *ep;
332			{
333			register VARDEF *vp;
334
335			vp = varinsert(dname(ep));
336			ep->sibling = vp->def;
337			vp->def = ep;
338			}
339
340
341			#ifdef OUTCHAN
342			addchan(sp) /* add an output channel assignment */
343			EPNODE *sp;
344			{
345			int ch = sp->v.kid->v.chan;
346			register EPNODE ep, epl;
347
348			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
349			if (ep->v.kid->v.chan >= ch) {
350			if (epl != NULL)
351			epl->sibling = sp;
352			else
353			outchan = sp;
354			if (ep->v.kid->v.chan > ch)
355			sp->sibling = ep;
356			else {
357			sp->sibling = ep->sibling;
358			epfree(ep);
359			}
360			return;
361			}
362			if (epl != NULL)
363			epl->sibling = sp;
364			else
365			outchan = sp;
366			sp->sibling = NULL;
367
368			}
369			#endif
370
371
372			loaddefn() /* load next definition */
373			{
374			register EPNODE *ep;
375
376			if (nextc == ';') { /* empty statement */
377			scan();
378			return;
379			}
380			#ifdef OUTCHAN
381			if (nextc == '$') { /* channel assignment */
382			ep = getchan();
383			addchan(ep);
384			} else
385			#endif
386			{ /* ordinary definition */
387			ep = getdefn();
388	greg	1.2	#ifdef REDEFW
389			if (dlookup(dname(ep)) != NULL) {
390	greg	1.8	dclear(dname(ep));
391			wputs(dname(ep));
392			if (dlookup(dname(ep)) == NULL)
393	greg	1.2	wputs(": redefined\n");
394	greg	1.8	else
395			wputs(": redefined constant expression\n");
396	greg	1.2	}
397	greg	1.8	#ifdef FUNCTION
398			else if (ep->v.kid->type == FUNC &&
399			liblookup(ep->v.kid->v.kid->v.name) != NULL) {
400			wputs(ep->v.kid->v.kid->v.name);
401			wputs(": redefined library function\n");
402			}
403			#endif
404	greg	1.2	#else
405	greg	1.1	dclear(dname(ep));
406	greg	1.2	#endif
407	greg	1.1	dpush(ep);
408			}
409			if (nextc != EOF) {
410			if (nextc != ';')
411			syntax("';' expected");
412			scan();
413			}
414			}
415
416
417			EPNODE *
418			getdefn() /* A -> SYM = E1 */
419	greg	1.8	/* SYM : E1 */
420	greg	1.1	/* FUNC(SYM,..) = E1 */
421	greg	1.8	/* FUNC(SYM,..) : E1 */
422	greg	1.1	{
423			register EPNODE ep1, ep2;
424
425			if (!isalpha(nextc))
426			syntax("illegal variable name");
427
428			ep1 = newnode();
429			ep1->type = SYM;
430			ep1->v.name = savestr(getname());
431
432			#ifdef FUNCTION
433			if (nextc == '(') {
434			ep2 = newnode();
435			ep2->type = FUNC;
436			addekid(ep2, ep1);
437			ep1 = ep2;
438			do {
439			scan();
440			if (!isalpha(nextc))
441			syntax("illegal variable name");
442			ep2 = newnode();
443			ep2->type = SYM;
444			ep2->v.name = savestr(getname());
445			addekid(ep1, ep2);
446			} while (nextc == ',');
447			if (nextc != ')')
448			syntax("')' expected");
449			scan();
450			curfunc = ep1;
451			} else
452			curfunc = NULL;
453			#endif
454
455	greg	1.8	if (nextc != '=' && nextc != ':')
456			syntax("'=' or ':' expected");
457	greg	1.1
458			ep2 = newnode();
459	greg	1.8	ep2->type = nextc;
460			scan();
461	greg	1.1	addekid(ep2, ep1);
462	greg	1.8	#ifdef RCONST
463			if (
464			#ifdef FUNCTION
465			ep1->type == SYM &&
466			#endif
467			ep2->type == ':')
468			addekid(ep2, rconst(getE1()));
469			else
470			#endif
471	greg	1.1	addekid(ep2, getE1());
472
473	greg	1.7	if (
474	greg	1.1	#ifdef FUNCTION
475	greg	1.7	ep1->type == SYM &&
476	greg	1.1	#endif
477	greg	1.7	ep1->sibling->type != NUM) {
478	greg	1.1	ep1 = newnode();
479			ep1->type = TICK;
480			ep1->v.tick = -1;
481			addekid(ep2, ep1);
482			ep1 = newnode();
483			ep1->type = NUM;
484			addekid(ep2, ep1);
485			}
486
487			return(ep2);
488			}
489
490
491			#ifdef OUTCHAN
492			EPNODE *
493			getchan() /* A -> $N = E1 */
494			{
495			register EPNODE ep1, ep2;
496
497			if (nextc != '$')
498			syntax("missing '$'");
499			scan();
500
501			ep1 = newnode();
502			ep1->type = CHAN;
503			ep1->v.chan = getinum();
504
505			if (nextc != '=')
506			syntax("'=' expected");
507			scan();
508
509			ep2 = newnode();
510			ep2->type = '=';
511			addekid(ep2, ep1);
512			addekid(ep2, getE1());
513
514			return(ep2);
515			}
516			#endif
517
518
519
520			/*
521			* The following routines are for internal use only:
522			*/
523
524
525			static double
526			dvalue(name, d) /* evaluate a variable */
527			char *name;
528			EPNODE *d;
529			{
530			register EPNODE ep1, ep2;
531
532			if (d == NULL \|\| d->v.kid->type != SYM) {
533			eputs(name);
534			eputs(": undefined variable\n");
535			quit(1);
536			}
537			ep1 = d->v.kid->sibling; /* get expression */
538	greg	1.5	if (ep1->type == NUM)
539			return(ep1->v.num); /* return if number */
540	greg	1.1	ep2 = ep1->sibling; /* check time */
541			if (ep2->v.tick < 0 \|\| ep2->v.tick < eclock) {
542	greg	1.8	ep2->v.tick = d->type == ':' ? 1L<<30 : eclock;
543	greg	1.1	ep2 = ep2->sibling;
544	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
545	greg	1.1	} else
546	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
547	greg	1.1
548			return(ep2->v.num);
549			}
550
551
552			static int
553			hash(s) /* hash a string */
554			register char *s;
555			{
556			register int rval = 0;
557
558			while (*s)
559			rval += *s++;
560
561			return(rval % NHASH);
562			}