src/common/caldefn.c

/* Copyright (c) 1991 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 ':' assignment for constant expressions
 *
 *  8/7/91  Added optional context path to append to variable names
 */

#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(), *strcpy();

static double  dvalue();

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

static char  context[MAXWORD];          /* current context path */

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)
        getstatement();
    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)
        getstatement();
}


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;
{
    char  *qname;
    register EPNODE  *ep1, *ep2;
                                        /* get qualified name */
    qname = qualname(vname, 0);
                                        /* check for quick set */
    if ((ep1 = dlookup(qname)) != 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(qname);
    dpush(qname, ep1);
}


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

    while ((ep = dpop(name)) != NULL) {
        if (ep->type == ':') {
            dpush(name, 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);
}


char *
setcontext(ctx)                 /* set a new context path */
register char  *ctx;
{
    register char  *cpp;

    if (ctx == NULL)
        return(context);                /* just asking */
    if (!*ctx) {
        context[0] = '\0';              /* clear context */
        return(context);
    }
    cpp = context;                      /* else copy it (carefully!) */
    if (*ctx != CNTXMARK)
        *cpp++ = CNTXMARK;              /* make sure there's a mark */
    do {
        if (cpp >= context+MAXWORD-1) {
            *cpp = '\0';
            wputs(context);
            wputs(": context path too long\n");
            return(NULL);
        }
        if (isid(*ctx))
            *cpp++ = *ctx++;
        else {
            *cpp++ = '_'; ctx++;
        }
    } while (*ctx);
    *cpp = '\0';
    return(context);
}


char *
qualname(nam, lvl)              /* get qualified name */
register char  *nam;
int  lvl;
{
    static char  nambuf[MAXWORD];
    register char  *cp = nambuf, *cpp = context;
                                /* check for explicit global */
    if (*nam == CNTXMARK)
        return(lvl > 0 ? NULL : nam+1);
                                /* check for repeat call */
    if (nam == nambuf)
        return(lvl > 0 ? NULL : nambuf);
                                /* copy name to static buffer */
    while (*nam) {
        if (cp >= nambuf+MAXWORD-1)
                goto toolong;
        if ((*cp++ = *nam++) == CNTXMARK)
            cpp = NULL;         /* flag a qualified name */
    }
    if (cpp == NULL) {
        if (lvl > 0)
            return(NULL);               /* no higher level */
        if (cp[-1] == CNTXMARK) {
            cp--; cpp = context;        /* current context explicitly */
        } else
            cpp = "";                   /* else fully qualified */
    } else                      /* else skip the requested levels */
        while (lvl-- > 0) {
            if (!*cpp)
                return(NULL);   /* return NULL if past global level */
            while (*++cpp && *cpp != CNTXMARK)
                ;
        }
    while (*cpp) {              /* copy context to static buffer */
        if (cp >= nambuf+MAXWORD-1)
            goto toolong;
        *cp++ = *cpp++;
    }
    *cp = '\0';
    return(nambuf);             /* return qualified name */
toolong:
    *cp = '\0';
    eputs(nambuf);
    eputs(": name too long\n");
    quit(1);
}


incontext(qn)                   /* is qualified name in current context? */
register char  *qn;
{
    while (*qn && *qn != CNTXMARK)      /* find context mark */
        ;
    return(!strcmp(qn, context));
}


#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


dcleanup(lvl)           /* clear definitions (0->vars,1->output,2->consts) */
int  lvl;
{
    register int  i;
    register VARDEF  *vp;
    register EPNODE  *ep;
                                /* if context is global, clear all */
    for (i = 0; i < NHASH; i++)
        for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
            if (!context[0] || incontext(vp->name))
                if (lvl >= 2)
                    dremove(vp->name);
                else
                    dclear(vp->name);
#ifdef  OUTCHAN
    if (lvl >= 1) {
        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;
{
    int  lvl = 0;
    register char  *qname;
    register VARDEF  *vp;
                                /* find most qualified match */
    while ((qname = qualname(name, lvl++)) != NULL)
        for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
            if (!strcmp(vp->name, qname))
                return(vp);
    return(NULL);
}


VARDEF *
varinsert(name)                 /* get a link to a variable */
char  *name;
{
    register VARDEF  *vp;
    int  hv;
    
    if ((vp = varlookup(name)) != NULL) {
        vp->nlinks++;
        return(vp);
    }
    name = qualname(name, 0);           /* use fully qualified name */
    hv = hash(name);
    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(nm, ep)                   /* push on a definition */
char  *nm;
register EPNODE  *ep;
{
    register VARDEF  *vp;

    vp = varinsert(nm);
    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


getstatement()                  /* get next statement */
{
    register EPNODE  *ep;
    char  *qname;
    EPNODE  *lastdef;

    if (nextc == ';') {         /* empty statement */
        scan();
        return;
    }
#ifdef  OUTCHAN
    if (nextc == '$') {         /* channel assignment */
        ep = getchan();
        addchan(ep);
    } else
#endif
    {                           /* ordinary definition */
        ep = getdefn();
        qname = qualname(dname(ep), 0);
#ifdef  REDEFW
        if ((lastdef = dlookup(qname)) != NULL) {
            wputs(qname);
            if (lastdef->type == ':')
                wputs(": redefined constant expression\n");
            else
                wputs(": redefined\n");
        }
#ifdef  FUNCTION
        else if (ep->v.kid->type == FUNC && liblookup(qname) != NULL) {
            wputs(qname);
            wputs(": definition hides library function\n");
        }
#endif
#endif
        if (ep->type == ':')
            dremove(qname);
        else
            dclear(qname);
        dpush(qname, 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);
    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:	1.15
Committed:	Thu Aug 8 12:28:30 1991 UTC (32 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.14:	+3 -0 lines
Log Message:	added explicit global id's starting with context mark
#	User	Rev	Content
1	greg	1.9	/* Copyright (c) 1991 Regents of the University of California */
2	greg	1.1
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	greg	1.10	* 4/23/91 Added ':' assignment for constant expressions
23	greg	1.13	*
24			* 8/7/91 Added optional context path to append to variable names
25	greg	1.1	*/
26
27			#include <stdio.h>
28
29			#include <ctype.h>
30
31			#include "calcomp.h"
32
33			#ifndef NHASH
34			#define NHASH 521 /* hash size (a prime!) */
35			#endif
36
37			#define newnode() (EPNODE *)ecalloc(1, sizeof(EPNODE))
38
39	greg	1.13	extern char ecalloc(), savestr(), *strcpy();
40	greg	1.1
41	greg	1.3	static double dvalue();
42	greg	1.1
43			long eclock = -1; /* value storage timer */
44
45	greg	1.13	static char context[MAXWORD]; /* current context path */
46
47	greg	1.1	static VARDEF hashtbl[NHASH]; / definition list */
48			static int htndx; /* index for */
49			static VARDEF htpos; / ...dfirst() and */
50			#ifdef OUTCHAN
51			static EPNODE ochpos; / ...dnext */
52			static EPNODE *outchan;
53			#endif
54
55			#ifdef FUNCTION
56			EPNODE *curfunc;
57			#define dname(ep) ((ep)->v.kid->type == SYM ? \
58			(ep)->v.kid->v.name : \
59			(ep)->v.kid->v.kid->v.name)
60			#else
61			#define dname(ep) ((ep)->v.kid->v.name)
62			#endif
63
64
65			fcompile(fname) /* get definitions from a file */
66			char *fname;
67			{
68			FILE *fp;
69
70			if (fname == NULL)
71			fp = stdin;
72			else if ((fp = fopen(fname, "r")) == NULL) {
73			eputs(fname);
74			eputs(": cannot open\n");
75			quit(1);
76			}
77	greg	1.4	initfile(fp, fname, 0);
78	greg	1.1	while (nextc != EOF)
79	greg	1.13	getstatement();
80	greg	1.1	if (fname != NULL)
81			fclose(fp);
82			}
83
84
85	greg	1.4	scompile(str, fn, ln) /* get definitions from a string */
86	greg	1.1	char *str;
87	greg	1.4	char *fn;
88			int ln;
89	greg	1.1	{
90	greg	1.4	initstr(str, fn, ln);
91	greg	1.1	while (nextc != EOF)
92	greg	1.13	getstatement();
93	greg	1.1	}
94
95
96			double
97			varvalue(vname) /* return a variable's value */
98			char *vname;
99			{
100			return(dvalue(vname, dlookup(vname)));
101			}
102
103
104			double
105			evariable(ep) /* evaluate a variable */
106			EPNODE *ep;
107			{
108			register VARDEF *dp = ep->v.ln;
109
110			return(dvalue(dp->name, dp->def));
111			}
112
113
114	greg	1.8	varset(vname, assign, val) /* set a variable's value */
115	greg	1.1	char *vname;
116	greg	1.8	int assign;
117	greg	1.1	double val;
118			{
119	greg	1.13	char *qname;
120	greg	1.1	register EPNODE ep1, ep2;
121	greg	1.13	/* get qualified name */
122			qname = qualname(vname, 0);
123	greg	1.1	/* check for quick set */
124	greg	1.13	if ((ep1 = dlookup(qname)) != NULL && ep1->v.kid->type == SYM) {
125	greg	1.1	ep2 = ep1->v.kid->sibling;
126			if (ep2->type == NUM) {
127			ep2->v.num = val;
128	greg	1.8	ep1->type = assign;
129	greg	1.1	return;
130			}
131			}
132			/* hand build definition */
133			ep1 = newnode();
134	greg	1.8	ep1->type = assign;
135	greg	1.1	ep2 = newnode();
136			ep2->type = SYM;
137			ep2->v.name = savestr(vname);
138			addekid(ep1, ep2);
139			ep2 = newnode();
140			ep2->type = NUM;
141			ep2->v.num = val;
142			addekid(ep1, ep2);
143	greg	1.13	dremove(qname);
144			dpush(qname, ep1);
145	greg	1.1	}
146
147
148	greg	1.8	dclear(name) /* delete variable definitions of name */
149	greg	1.1	char *name;
150			{
151			register EPNODE *ep;
152
153	greg	1.8	while ((ep = dpop(name)) != NULL) {
154			if (ep->type == ':') {
155	greg	1.13	dpush(name, ep); /* don't clear constants */
156	greg	1.8	return;
157			}
158			epfree(ep);
159			}
160			}
161
162
163			dremove(name) /* delete all definitions of name */
164			char *name;
165			{
166			register EPNODE *ep;
167
168	greg	1.1	while ((ep = dpop(name)) != NULL)
169			epfree(ep);
170			}
171
172
173			vardefined(name) /* return non-zero if variable defined */
174			char *name;
175			{
176			register EPNODE *dp;
177
178			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
179			}
180
181
182	greg	1.13	char *
183			setcontext(ctx) /* set a new context path */
184			register char *ctx;
185			{
186			register char *cpp;
187
188			if (ctx == NULL)
189			return(context); /* just asking */
190			if (!*ctx) {
191			context[0] = '\0'; /* clear context */
192			return(context);
193			}
194			cpp = context; /* else copy it (carefully!) */
195			if (*ctx != CNTXMARK)
196			cpp++ = CNTXMARK; / make sure there's a mark */
197			do {
198			if (cpp >= context+MAXWORD-1) {
199			*cpp = '\0';
200			wputs(context);
201			wputs(": context path too long\n");
202			return(NULL);
203			}
204			if (isid(*ctx))
205			cpp++ = ctx++;
206			else {
207			*cpp++ = '_'; ctx++;
208			}
209			} while (*ctx);
210			*cpp = '\0';
211			return(context);
212			}
213
214
215			char *
216			qualname(nam, lvl) /* get qualified name */
217			register char *nam;
218			int lvl;
219			{
220			static char nambuf[MAXWORD];
221			register char cp = nambuf, cpp = context;
222	greg	1.15	/* check for explicit global */
223			if (*nam == CNTXMARK)
224			return(lvl > 0 ? NULL : nam+1);
225	greg	1.13	/* check for repeat call */
226			if (nam == nambuf)
227			return(lvl > 0 ? NULL : nambuf);
228			/* copy name to static buffer */
229			while (*nam) {
230			if (cp >= nambuf+MAXWORD-1)
231			goto toolong;
232			if ((cp++ = nam++) == CNTXMARK)
233			cpp = NULL; /* flag a qualified name */
234			}
235			if (cpp == NULL) {
236			if (lvl > 0)
237			return(NULL); /* no higher level */
238			if (cp[-1] == CNTXMARK) {
239			cp--; cpp = context; /* current context explicitly */
240			} else
241			cpp = ""; /* else fully qualified */
242			} else /* else skip the requested levels */
243			while (lvl-- > 0) {
244			if (!*cpp)
245			return(NULL); /* return NULL if past global level */
246			while (++cpp && cpp != CNTXMARK)
247			;
248			}
249			while (cpp) { / copy context to static buffer */
250			if (cp >= nambuf+MAXWORD-1)
251			goto toolong;
252			cp++ = cpp++;
253			}
254			*cp = '\0';
255			return(nambuf); /* return qualified name */
256			toolong:
257			*cp = '\0';
258	greg	1.14	eputs(nambuf);
259			eputs(": name too long\n");
260			quit(1);
261	greg	1.13	}
262
263
264	greg	1.14	incontext(qn) /* is qualified name in current context? */
265			register char *qn;
266			{
267			while (qn && qn != CNTXMARK) /* find context mark */
268			;
269			return(!strcmp(qn, context));
270			}
271
272
273	greg	1.1	#ifdef OUTCHAN
274	greg	1.6	chanout(cs) /* set output channels */
275			int (*cs)();
276	greg	1.1	{
277			register EPNODE *ep;
278
279			for (ep = outchan; ep != NULL; ep = ep->sibling)
280	greg	1.6	(*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
281	greg	1.1
282			}
283			#endif
284
285
286	greg	1.12	dcleanup(lvl) /* clear definitions (0->vars,1->output,2->consts) */
287	greg	1.10	int lvl;
288	greg	1.1	{
289			register int i;
290			register VARDEF *vp;
291			register EPNODE *ep;
292	greg	1.14	/* if context is global, clear all */
293	greg	1.1	for (i = 0; i < NHASH; i++)
294			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
295	greg	1.14	if (!context[0] \|\| incontext(vp->name))
296			if (lvl >= 2)
297			dremove(vp->name);
298			else
299			dclear(vp->name);
300	greg	1.1	#ifdef OUTCHAN
301	greg	1.12	if (lvl >= 1) {
302	greg	1.9	for (ep = outchan; ep != NULL; ep = ep->sibling)
303			epfree(ep);
304			outchan = NULL;
305			}
306	greg	1.1	#endif
307			}
308
309
310			EPNODE *
311			dlookup(name) /* look up a definition */
312			char *name;
313			{
314			register VARDEF *vp;
315
316			if ((vp = varlookup(name)) == NULL)
317			return(NULL);
318			return(vp->def);
319			}
320
321
322			VARDEF *
323			varlookup(name) /* look up a variable */
324			char *name;
325			{
326	greg	1.13	int lvl = 0;
327			register char *qname;
328	greg	1.1	register VARDEF *vp;
329	greg	1.13	/* find most qualified match */
330			while ((qname = qualname(name, lvl++)) != NULL)
331			for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
332			if (!strcmp(vp->name, qname))
333			return(vp);
334	greg	1.1	return(NULL);
335			}
336
337
338			VARDEF *
339			varinsert(name) /* get a link to a variable */
340			char *name;
341			{
342			register VARDEF *vp;
343			int hv;
344
345	greg	1.13	if ((vp = varlookup(name)) != NULL) {
346			vp->nlinks++;
347			return(vp);
348			}
349			name = qualname(name, 0); /* use fully qualified name */
350	greg	1.1	hv = hash(name);
351			vp = (VARDEF *)emalloc(sizeof(VARDEF));
352			vp->name = savestr(name);
353			vp->nlinks = 1;
354			vp->def = NULL;
355			vp->lib = NULL;
356			vp->next = hashtbl[hv];
357			hashtbl[hv] = vp;
358			return(vp);
359			}
360
361
362			varfree(ln) /* release link to variable */
363			register VARDEF *ln;
364			{
365			register VARDEF *vp;
366			int hv;
367
368			if (--ln->nlinks > 0)
369			return; /* still active */
370
371			hv = hash(ln->name);
372			vp = hashtbl[hv];
373			if (vp == ln)
374			hashtbl[hv] = vp->next;
375			else {
376			while (vp->next != ln) /* must be in list */
377			vp = vp->next;
378			vp->next = ln->next;
379			}
380			freestr(ln->name);
381			efree((char *)ln);
382			}
383
384
385			EPNODE *
386			dfirst() /* return pointer to first definition */
387			{
388			htndx = 0;
389			htpos = NULL;
390			#ifdef OUTCHAN
391			ochpos = outchan;
392			#endif
393			return(dnext());
394			}
395
396
397			EPNODE *
398			dnext() /* return pointer to next definition */
399			{
400			register EPNODE *ep;
401
402			while (htndx < NHASH) {
403			if (htpos == NULL)
404			htpos = hashtbl[htndx++];
405			while (htpos != NULL) {
406			ep = htpos->def;
407			htpos = htpos->next;
408			if (ep != NULL)
409			return(ep);
410			}
411			}
412			#ifdef OUTCHAN
413			if ((ep = ochpos) != NULL)
414			ochpos = ep->sibling;
415			return(ep);
416			#else
417			return(NULL);
418			#endif
419			}
420
421
422			EPNODE *
423			dpop(name) /* pop a definition */
424			char *name;
425			{
426			register VARDEF *vp;
427			register EPNODE *dp;
428
429			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
430			return(NULL);
431			dp = vp->def;
432			vp->def = dp->sibling;
433			varfree(vp);
434			return(dp);
435			}
436
437
438	greg	1.13	dpush(nm, ep) /* push on a definition */
439			char *nm;
440	greg	1.1	register EPNODE *ep;
441			{
442			register VARDEF *vp;
443
444	greg	1.13	vp = varinsert(nm);
445	greg	1.1	ep->sibling = vp->def;
446			vp->def = ep;
447			}
448
449
450			#ifdef OUTCHAN
451			addchan(sp) /* add an output channel assignment */
452			EPNODE *sp;
453			{
454			int ch = sp->v.kid->v.chan;
455			register EPNODE ep, epl;
456
457			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
458			if (ep->v.kid->v.chan >= ch) {
459			if (epl != NULL)
460			epl->sibling = sp;
461			else
462			outchan = sp;
463			if (ep->v.kid->v.chan > ch)
464			sp->sibling = ep;
465			else {
466			sp->sibling = ep->sibling;
467			epfree(ep);
468			}
469			return;
470			}
471			if (epl != NULL)
472			epl->sibling = sp;
473			else
474			outchan = sp;
475			sp->sibling = NULL;
476
477			}
478			#endif
479
480
481	greg	1.13	getstatement() /* get next statement */
482	greg	1.1	{
483			register EPNODE *ep;
484	greg	1.13	char *qname;
485	greg	1.10	EPNODE *lastdef;
486	greg	1.1
487			if (nextc == ';') { /* empty statement */
488			scan();
489			return;
490			}
491			#ifdef OUTCHAN
492			if (nextc == '$') { /* channel assignment */
493			ep = getchan();
494			addchan(ep);
495			} else
496			#endif
497			{ /* ordinary definition */
498			ep = getdefn();
499	greg	1.13	qname = qualname(dname(ep), 0);
500	greg	1.2	#ifdef REDEFW
501	greg	1.13	if ((lastdef = dlookup(qname)) != NULL) {
502			wputs(qname);
503	greg	1.10	if (lastdef->type == ':')
504			wputs(": redefined constant expression\n");
505			else
506	greg	1.2	wputs(": redefined\n");
507			}
508	greg	1.8	#ifdef FUNCTION
509	greg	1.13	else if (ep->v.kid->type == FUNC && liblookup(qname) != NULL) {
510			wputs(qname);
511	greg	1.11	wputs(": definition hides library function\n");
512	greg	1.8	}
513			#endif
514	greg	1.2	#endif
515	greg	1.10	if (ep->type == ':')
516	greg	1.13	dremove(qname);
517	greg	1.10	else
518	greg	1.13	dclear(qname);
519			dpush(qname, ep);
520	greg	1.1	}
521			if (nextc != EOF) {
522			if (nextc != ';')
523			syntax("';' expected");
524			scan();
525			}
526			}
527
528
529			EPNODE *
530			getdefn() /* A -> SYM = E1 */
531	greg	1.8	/* SYM : E1 */
532	greg	1.1	/* FUNC(SYM,..) = E1 */
533	greg	1.8	/* FUNC(SYM,..) : E1 */
534	greg	1.1	{
535			register EPNODE ep1, ep2;
536
537			if (!isalpha(nextc))
538			syntax("illegal variable name");
539
540			ep1 = newnode();
541			ep1->type = SYM;
542			ep1->v.name = savestr(getname());
543
544			#ifdef FUNCTION
545			if (nextc == '(') {
546			ep2 = newnode();
547			ep2->type = FUNC;
548			addekid(ep2, ep1);
549			ep1 = ep2;
550			do {
551			scan();
552			if (!isalpha(nextc))
553			syntax("illegal variable name");
554			ep2 = newnode();
555			ep2->type = SYM;
556			ep2->v.name = savestr(getname());
557			addekid(ep1, ep2);
558			} while (nextc == ',');
559			if (nextc != ')')
560			syntax("')' expected");
561			scan();
562			curfunc = ep1;
563			} else
564			curfunc = NULL;
565			#endif
566
567	greg	1.8	if (nextc != '=' && nextc != ':')
568			syntax("'=' or ':' expected");
569	greg	1.1
570			ep2 = newnode();
571	greg	1.8	ep2->type = nextc;
572			scan();
573	greg	1.1	addekid(ep2, ep1);
574			addekid(ep2, getE1());
575
576	greg	1.7	if (
577	greg	1.1	#ifdef FUNCTION
578	greg	1.7	ep1->type == SYM &&
579	greg	1.1	#endif
580	greg	1.7	ep1->sibling->type != NUM) {
581	greg	1.1	ep1 = newnode();
582			ep1->type = TICK;
583			ep1->v.tick = -1;
584			addekid(ep2, ep1);
585			ep1 = newnode();
586			ep1->type = NUM;
587			addekid(ep2, ep1);
588			}
589
590			return(ep2);
591			}
592
593
594			#ifdef OUTCHAN
595			EPNODE *
596			getchan() /* A -> $N = E1 */
597			{
598			register EPNODE ep1, ep2;
599
600			if (nextc != '$')
601			syntax("missing '$'");
602			scan();
603
604			ep1 = newnode();
605			ep1->type = CHAN;
606			ep1->v.chan = getinum();
607
608			if (nextc != '=')
609			syntax("'=' expected");
610			scan();
611
612			ep2 = newnode();
613			ep2->type = '=';
614			addekid(ep2, ep1);
615			addekid(ep2, getE1());
616
617			return(ep2);
618			}
619			#endif
620
621
622
623			/*
624			* The following routines are for internal use only:
625			*/
626
627
628			static double
629			dvalue(name, d) /* evaluate a variable */
630			char *name;
631			EPNODE *d;
632			{
633			register EPNODE ep1, ep2;
634
635			if (d == NULL \|\| d->v.kid->type != SYM) {
636			eputs(name);
637			eputs(": undefined variable\n");
638			quit(1);
639			}
640			ep1 = d->v.kid->sibling; /* get expression */
641	greg	1.5	if (ep1->type == NUM)
642			return(ep1->v.num); /* return if number */
643	greg	1.1	ep2 = ep1->sibling; /* check time */
644			if (ep2->v.tick < 0 \|\| ep2->v.tick < eclock) {
645	greg	1.8	ep2->v.tick = d->type == ':' ? 1L<<30 : eclock;
646	greg	1.1	ep2 = ep2->sibling;
647	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
648	greg	1.1	} else
649	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
650	greg	1.1
651			return(ep2->v.num);
652			}
653
654
655			static int
656			hash(s) /* hash a string */
657			register char *s;
658			{
659			register int rval = 0;
660
661			while (*s)
662			rval += *s++;
663
664			return(rval % NHASH);
665			}