src/common/caldefn.c

/* Copyright (c) 1992 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  hash(s)        (shash(s)%NHASH)

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

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

static double  dvalue();

unsigned long  eclock = 0;              /* value storage timer */

static char  context[MAXWORD+1];        /* 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 */
    while (*ctx == CNTXMARK)
        ctx++;                          /* skip past marks */
    if (!*ctx) {
        context[0] = '\0';              /* empty means clear context */
        return(context);
    }
    cpp = context;                      /* start context with mark */
    *cpp++ = CNTXMARK;
    do {                                /* carefully copy new context */
        if (cpp >= context+MAXWORD)
            break;                      /* just copy what we can */
        if (isid(*ctx))
            *cpp++ = *ctx++;
        else {
            *cpp++ = '_'; ctx++;
        }
    } while (*ctx);
    while (cpp[-1] == CNTXMARK)         /* cannot end in context mark */
        cpp--;
    *cpp = '\0';
    return(context);
}


char *
pushcontext(ctx)                /* push on another context */
char  *ctx;
{
    extern char  *strncpy(), *strcpy();
    char  oldcontext[MAXWORD+1];
    register int  n;

    strcpy(oldcontext, context);        /* save old context */
    setcontext(ctx);                    /* set new context */
    n = strlen(context);                /* tack on old */
    if (n+strlen(oldcontext) > MAXWORD) {
        strncpy(context+n, oldcontext, MAXWORD-n);
        context[MAXWORD] = '\0';
    } else
        strcpy(context+n, oldcontext);
    return(context);
}


char *
popcontext()                    /* pop off top context */
{
    register char  *cp1, *cp2;

    if (!context[0])                    /* nothing left to pop */
        return(context);
    cp2 = context;                      /* find mark */
    while (*++cp2 && *cp2 != CNTXMARK)
        ;
    cp1 = context;                      /* copy tail to front */
    while (*cp1++ = *cp2++)
        ;
    return(context);
}


char *
qualname(nam, lvl)              /* get qualified name */
register char  *nam;
int  lvl;
{
    static char  nambuf[MAXWORD+1];
    register char  *cp = nambuf, *cpp;
                                /* check for explicit local */
    if (*nam == CNTXMARK)
        if (lvl > 0)            /* only action is to refuse search */
            return(NULL);
        else
            nam++;
    else if (nam == nambuf)     /* check for repeat call */
        return(lvl > 0 ? NULL : nam);
                                /* copy name to static buffer */
    while (*nam) {
        if (cp >= nambuf+MAXWORD)
                goto toolong;
        *cp++ = *nam++;
    }
                                /* check for explicit global */
    if (cp > nambuf && cp[-1] == CNTXMARK) {
        if (lvl > 0)
            return(NULL);
        *--cp = '\0';
        return(nambuf);         /* already qualified */
    }
    cpp = context;              /* 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)
            goto toolong;
        *cp++ = *cpp++;
    }
toolong:
    *cp = '\0';
    return(nambuf);             /* return qualified name */
}


incontext(qn)                   /* is qualified name in current context? */
register char  *qn;
{
    while (*qn && *qn != CNTXMARK)      /* find context mark */
        qn++;
    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);
    }
    vp = (VARDEF *)emalloc(sizeof(VARDEF));
#ifdef  FUNCTION
    vp->lib = liblookup(name);
#else
    vp->lib = NULL;
#endif
    if (vp->lib == NULL)                /* if name not in library */
        name = qualname(name, 0);       /* use fully qualified version */
    hv = hash(name);
    vp->name = savestr(name);
    vp->nlinks = 1;
    vp->def = NULL;
    vp->next = hashtbl[hv];
    hashtbl[hv] = vp;
    return(vp);
}


#ifdef  FUNCTION
libupdate(fn)                   /* update library links */
char  *fn;
{
    register int  i;
    register VARDEF  *vp;
                                        /* if fn is NULL then relink all */
    for (i = 0; i < NHASH; i++)
        for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
            if (vp->lib != NULL || fn == NULL || !strcmp(fn, vp->name))
                vp->lib = liblookup(vp->name);
}
#endif


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;
    register char  *nm;

    while (htndx < NHASH) {
        if (htpos == NULL)
                htpos = hashtbl[htndx++];
        while (htpos != NULL) {
            ep = htpos->def;
            nm = htpos->name;
            htpos = htpos->next;
            if (ep != NULL && incontext(nm))
                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;
    register VARDEF  *vdef;

    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 ((vdef = varlookup(qname)) != NULL)
            if (vdef->def != NULL && epcmp(ep, vdef->def)) {
                wputs(qname);
                if (vdef->def->type == ':')
                    wputs(": redefined constant expression\n");
                else
                    wputs(": redefined\n");
            }
#ifdef  FUNCTION
            else if (ep->v.kid->type == FUNC && vdef->lib != 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) && nextc != CNTXMARK)
        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 = 0;
        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 == ':' ? ~0L : eclock;
        ep2 = ep2->sibling;
        ep2->v.num = evalue(ep1);               /* needs new value */
    } else
        ep2 = ep2->sibling;                     /* else reuse old value */

    return(ep2->v.num);
}
Revision:	2.8
Committed:	Fri Feb 17 18:34:42 1995 UTC (29 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.7:	+4 -4 lines
Log Message:	fixed potential bug in eclock tracking
#	User	Rev	Content
1	greg	2.4	/* Copyright (c) 1992 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	greg	2.4	#ifndef NHASH
34			#define NHASH 521 /* hash size (a prime!) */
35	greg	1.1	#endif
36
37	greg	2.5	#define hash(s) (shash(s)%NHASH)
38
39	greg	2.4	#define newnode() (EPNODE *)ecalloc(1, sizeof(EPNODE))
40	greg	1.1
41	greg	2.4	extern char ecalloc(), emalloc(), savestr(), strcpy();
42	greg	1.1
43	greg	1.3	static double dvalue();
44	greg	1.1
45	greg	2.8	unsigned long eclock = 0; /* value storage timer */
46	greg	1.1
47	greg	1.18	static char context[MAXWORD+1]; /* current context path */
48	greg	1.13
49	greg	1.1	static VARDEF hashtbl[NHASH]; / definition list */
50			static int htndx; /* index for */
51			static VARDEF htpos; / ...dfirst() and */
52	greg	2.4	#ifdef OUTCHAN
53	greg	1.1	static EPNODE ochpos; / ...dnext */
54			static EPNODE *outchan;
55			#endif
56
57	greg	2.4	#ifdef FUNCTION
58			EPNODE *curfunc;
59			#define dname(ep) ((ep)->v.kid->type == SYM ? \
60	greg	1.1	(ep)->v.kid->v.name : \
61			(ep)->v.kid->v.kid->v.name)
62			#else
63	greg	2.4	#define dname(ep) ((ep)->v.kid->v.name)
64	greg	1.1	#endif
65
66
67			fcompile(fname) /* get definitions from a file */
68			char *fname;
69			{
70			FILE *fp;
71
72			if (fname == NULL)
73			fp = stdin;
74			else if ((fp = fopen(fname, "r")) == NULL) {
75			eputs(fname);
76			eputs(": cannot open\n");
77			quit(1);
78			}
79	greg	1.4	initfile(fp, fname, 0);
80	greg	1.1	while (nextc != EOF)
81	greg	1.13	getstatement();
82	greg	1.1	if (fname != NULL)
83			fclose(fp);
84			}
85
86
87	greg	1.4	scompile(str, fn, ln) /* get definitions from a string */
88	greg	1.1	char *str;
89	greg	1.4	char *fn;
90			int ln;
91	greg	1.1	{
92	greg	1.4	initstr(str, fn, ln);
93	greg	1.1	while (nextc != EOF)
94	greg	1.13	getstatement();
95	greg	1.1	}
96
97
98			double
99			varvalue(vname) /* return a variable's value */
100			char *vname;
101			{
102			return(dvalue(vname, dlookup(vname)));
103			}
104
105
106			double
107			evariable(ep) /* evaluate a variable */
108	greg	2.4	EPNODE *ep;
109	greg	1.1	{
110			register VARDEF *dp = ep->v.ln;
111
112			return(dvalue(dp->name, dp->def));
113			}
114
115
116	greg	1.8	varset(vname, assign, val) /* set a variable's value */
117	greg	1.1	char *vname;
118	greg	1.8	int assign;
119	greg	2.4	double val;
120	greg	1.1	{
121	greg	1.13	char *qname;
122	greg	1.1	register EPNODE ep1, ep2;
123	greg	1.13	/* get qualified name */
124			qname = qualname(vname, 0);
125	greg	1.1	/* check for quick set */
126	greg	1.13	if ((ep1 = dlookup(qname)) != NULL && ep1->v.kid->type == SYM) {
127	greg	1.1	ep2 = ep1->v.kid->sibling;
128			if (ep2->type == NUM) {
129			ep2->v.num = val;
130	greg	1.8	ep1->type = assign;
131	greg	1.1	return;
132			}
133			}
134			/* hand build definition */
135			ep1 = newnode();
136	greg	1.8	ep1->type = assign;
137	greg	1.1	ep2 = newnode();
138			ep2->type = SYM;
139			ep2->v.name = savestr(vname);
140			addekid(ep1, ep2);
141			ep2 = newnode();
142			ep2->type = NUM;
143			ep2->v.num = val;
144			addekid(ep1, ep2);
145	greg	1.13	dremove(qname);
146			dpush(qname, ep1);
147	greg	1.1	}
148
149
150	greg	1.8	dclear(name) /* delete variable definitions of name */
151	greg	1.1	char *name;
152			{
153			register EPNODE *ep;
154
155	greg	1.8	while ((ep = dpop(name)) != NULL) {
156			if (ep->type == ':') {
157	greg	1.13	dpush(name, ep); /* don't clear constants */
158	greg	1.8	return;
159			}
160			epfree(ep);
161			}
162			}
163
164
165			dremove(name) /* delete all definitions of name */
166			char *name;
167			{
168			register EPNODE *ep;
169
170	greg	1.1	while ((ep = dpop(name)) != NULL)
171			epfree(ep);
172			}
173
174
175			vardefined(name) /* return non-zero if variable defined */
176			char *name;
177			{
178			register EPNODE *dp;
179
180			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
181			}
182
183
184	greg	1.13	char *
185			setcontext(ctx) /* set a new context path */
186			register char *ctx;
187			{
188			register char *cpp;
189
190			if (ctx == NULL)
191			return(context); /* just asking */
192	greg	2.6	while (*ctx == CNTXMARK)
193			ctx++; /* skip past marks */
194	greg	1.13	if (!*ctx) {
195	greg	2.6	context[0] = '\0'; /* empty means clear context */
196	greg	1.13	return(context);
197			}
198	greg	2.6	cpp = context; /* start context with mark */
199			*cpp++ = CNTXMARK;
200			do { /* carefully copy new context */
201	greg	1.18	if (cpp >= context+MAXWORD)
202			break; /* just copy what we can */
203	greg	1.13	if (isid(*ctx))
204			cpp++ = ctx++;
205			else {
206			*cpp++ = '_'; ctx++;
207			}
208			} while (*ctx);
209	greg	2.6	while (cpp[-1] == CNTXMARK) /* cannot end in context mark */
210			cpp--;
211	greg	1.13	*cpp = '\0';
212	greg	2.6	return(context);
213			}
214
215
216			char *
217			pushcontext(ctx) /* push on another context */
218			char *ctx;
219			{
220			extern char strncpy(), strcpy();
221			char oldcontext[MAXWORD+1];
222			register int n;
223
224			strcpy(oldcontext, context); /* save old context */
225			setcontext(ctx); /* set new context */
226			n = strlen(context); /* tack on old */
227			if (n+strlen(oldcontext) > MAXWORD) {
228			strncpy(context+n, oldcontext, MAXWORD-n);
229			context[MAXWORD] = '\0';
230			} else
231			strcpy(context+n, oldcontext);
232			return(context);
233			}
234
235
236			char *
237			popcontext() /* pop off top context */
238			{
239			register char cp1, cp2;
240
241			if (!context[0]) /* nothing left to pop */
242			return(context);
243			cp2 = context; /* find mark */
244			while (++cp2 && cp2 != CNTXMARK)
245			;
246			cp1 = context; /* copy tail to front */
247			while (cp1++ = cp2++)
248			;
249	greg	1.13	return(context);
250			}
251
252
253			char *
254			qualname(nam, lvl) /* get qualified name */
255			register char *nam;
256			int lvl;
257			{
258	greg	2.4	static char nambuf[MAXWORD+1];
259	greg	1.17	register char cp = nambuf, cpp;
260			/* check for explicit local */
261	greg	1.15	if (*nam == CNTXMARK)
262	greg	1.17	if (lvl > 0) /* only action is to refuse search */
263			return(NULL);
264			else
265			nam++;
266			else if (nam == nambuf) /* check for repeat call */
267			return(lvl > 0 ? NULL : nam);
268	greg	1.13	/* copy name to static buffer */
269			while (*nam) {
270	greg	1.18	if (cp >= nambuf+MAXWORD)
271	greg	1.13	goto toolong;
272	greg	1.17	cp++ = nam++;
273	greg	1.13	}
274	greg	1.17	/* check for explicit global */
275			if (cp > nambuf && cp[-1] == CNTXMARK) {
276	greg	1.13	if (lvl > 0)
277	greg	1.17	return(NULL);
278			*--cp = '\0';
279			return(nambuf); /* already qualified */
280			}
281			cpp = context; /* else skip the requested levels */
282			while (lvl-- > 0) {
283			if (!*cpp)
284			return(NULL); /* return NULL if past global level */
285			while (++cpp && cpp != CNTXMARK)
286			;
287			}
288	greg	1.13	while (cpp) { / copy context to static buffer */
289	greg	1.18	if (cp >= nambuf+MAXWORD)
290	greg	1.13	goto toolong;
291			cp++ = cpp++;
292			}
293	greg	1.18	toolong:
294	greg	1.13	*cp = '\0';
295			return(nambuf); /* return qualified name */
296			}
297
298
299	greg	1.14	incontext(qn) /* is qualified name in current context? */
300			register char *qn;
301			{
302			while (qn && qn != CNTXMARK) /* find context mark */
303	greg	1.19	qn++;
304	greg	1.14	return(!strcmp(qn, context));
305			}
306
307
308	greg	2.4	#ifdef OUTCHAN
309	greg	1.6	chanout(cs) /* set output channels */
310			int (*cs)();
311	greg	1.1	{
312			register EPNODE *ep;
313
314			for (ep = outchan; ep != NULL; ep = ep->sibling)
315	greg	1.6	(*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
316	greg	1.1
317			}
318			#endif
319
320
321	greg	1.12	dcleanup(lvl) /* clear definitions (0->vars,1->output,2->consts) */
322	greg	1.10	int lvl;
323	greg	1.1	{
324			register int i;
325			register VARDEF *vp;
326			register EPNODE *ep;
327	greg	1.14	/* if context is global, clear all */
328	greg	1.1	for (i = 0; i < NHASH; i++)
329			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
330	greg	1.14	if (!context[0] \|\| incontext(vp->name))
331			if (lvl >= 2)
332			dremove(vp->name);
333			else
334			dclear(vp->name);
335	greg	2.4	#ifdef OUTCHAN
336	greg	1.12	if (lvl >= 1) {
337	greg	1.9	for (ep = outchan; ep != NULL; ep = ep->sibling)
338			epfree(ep);
339			outchan = NULL;
340			}
341	greg	1.1	#endif
342			}
343
344
345			EPNODE *
346			dlookup(name) /* look up a definition */
347			char *name;
348			{
349			register VARDEF *vp;
350
351			if ((vp = varlookup(name)) == NULL)
352	greg	2.4	return(NULL);
353	greg	1.1	return(vp->def);
354			}
355
356
357			VARDEF *
358			varlookup(name) /* look up a variable */
359			char *name;
360			{
361	greg	2.4	int lvl = 0;
362	greg	1.13	register char *qname;
363	greg	1.1	register VARDEF *vp;
364	greg	2.4	/* find most qualified match */
365	greg	1.13	while ((qname = qualname(name, lvl++)) != NULL)
366			for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
367			if (!strcmp(vp->name, qname))
368			return(vp);
369	greg	1.1	return(NULL);
370			}
371
372
373			VARDEF *
374			varinsert(name) /* get a link to a variable */
375			char *name;
376			{
377			register VARDEF *vp;
378	greg	2.4	int hv;
379	greg	1.1
380	greg	1.13	if ((vp = varlookup(name)) != NULL) {
381			vp->nlinks++;
382			return(vp);
383			}
384	greg	2.3	vp = (VARDEF *)emalloc(sizeof(VARDEF));
385	greg	2.4	#ifdef FUNCTION
386	greg	2.3	vp->lib = liblookup(name);
387	greg	1.16	#else
388	greg	2.3	vp->lib = NULL;
389	greg	1.16	#endif
390	greg	2.3	if (vp->lib == NULL) /* if name not in library */
391	greg	1.16	name = qualname(name, 0); /* use fully qualified version */
392	greg	1.1	hv = hash(name);
393			vp->name = savestr(name);
394			vp->nlinks = 1;
395			vp->def = NULL;
396			vp->next = hashtbl[hv];
397			hashtbl[hv] = vp;
398			return(vp);
399			}
400	greg	2.2
401
402	greg	2.4	#ifdef FUNCTION
403	greg	2.2	libupdate(fn) /* update library links */
404			char *fn;
405			{
406			register int i;
407			register VARDEF *vp;
408			/* if fn is NULL then relink all */
409			for (i = 0; i < NHASH; i++)
410			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
411			if (vp->lib != NULL \|\| fn == NULL \|\| !strcmp(fn, vp->name))
412			vp->lib = liblookup(vp->name);
413			}
414			#endif
415	greg	1.1
416
417			varfree(ln) /* release link to variable */
418	greg	2.4	register VARDEF *ln;
419	greg	1.1	{
420			register VARDEF *vp;
421	greg	2.4	int hv;
422	greg	1.1
423			if (--ln->nlinks > 0)
424	greg	2.4	return; /* still active */
425	greg	1.1
426			hv = hash(ln->name);
427			vp = hashtbl[hv];
428			if (vp == ln)
429	greg	2.4	hashtbl[hv] = vp->next;
430	greg	1.1	else {
431	greg	2.4	while (vp->next != ln) /* must be in list */
432			vp = vp->next;
433			vp->next = ln->next;
434	greg	1.1	}
435			freestr(ln->name);
436			efree((char *)ln);
437			}
438
439
440			EPNODE *
441			dfirst() /* return pointer to first definition */
442			{
443			htndx = 0;
444			htpos = NULL;
445	greg	2.4	#ifdef OUTCHAN
446	greg	1.1	ochpos = outchan;
447			#endif
448			return(dnext());
449			}
450
451
452			EPNODE *
453			dnext() /* return pointer to next definition */
454			{
455			register EPNODE *ep;
456	greg	1.19	register char *nm;
457	greg	1.1
458			while (htndx < NHASH) {
459	greg	2.4	if (htpos == NULL)
460			htpos = hashtbl[htndx++];
461			while (htpos != NULL) {
462			ep = htpos->def;
463	greg	1.19	nm = htpos->name;
464	greg	2.4	htpos = htpos->next;
465			if (ep != NULL && incontext(nm))
466			return(ep);
467			}
468	greg	1.1	}
469	greg	2.4	#ifdef OUTCHAN
470	greg	1.1	if ((ep = ochpos) != NULL)
471	greg	2.4	ochpos = ep->sibling;
472	greg	1.1	return(ep);
473			#else
474			return(NULL);
475			#endif
476			}
477
478
479			EPNODE *
480			dpop(name) /* pop a definition */
481			char *name;
482			{
483			register VARDEF *vp;
484			register EPNODE *dp;
485
486			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
487	greg	2.4	return(NULL);
488	greg	1.1	dp = vp->def;
489			vp->def = dp->sibling;
490			varfree(vp);
491			return(dp);
492			}
493
494
495	greg	1.13	dpush(nm, ep) /* push on a definition */
496			char *nm;
497	greg	2.4	register EPNODE *ep;
498	greg	1.1	{
499			register VARDEF *vp;
500
501	greg	1.13	vp = varinsert(nm);
502	greg	1.1	ep->sibling = vp->def;
503			vp->def = ep;
504			}
505
506
507	greg	2.4	#ifdef OUTCHAN
508	greg	1.1	addchan(sp) /* add an output channel assignment */
509	greg	2.4	EPNODE *sp;
510	greg	1.1	{
511	greg	2.4	int ch = sp->v.kid->v.chan;
512	greg	1.1	register EPNODE ep, epl;
513
514			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
515			if (ep->v.kid->v.chan >= ch) {
516			if (epl != NULL)
517			epl->sibling = sp;
518			else
519			outchan = sp;
520			if (ep->v.kid->v.chan > ch)
521			sp->sibling = ep;
522			else {
523			sp->sibling = ep->sibling;
524			epfree(ep);
525			}
526			return;
527			}
528			if (epl != NULL)
529			epl->sibling = sp;
530			else
531			outchan = sp;
532			sp->sibling = NULL;
533
534			}
535			#endif
536
537
538	greg	1.13	getstatement() /* get next statement */
539	greg	1.1	{
540			register EPNODE *ep;
541	greg	1.13	char *qname;
542	greg	1.16	register VARDEF *vdef;
543	greg	1.1
544			if (nextc == ';') { /* empty statement */
545			scan();
546			return;
547			}
548	greg	2.4	#ifdef OUTCHAN
549	greg	1.1	if (nextc == '$') { /* channel assignment */
550			ep = getchan();
551			addchan(ep);
552			} else
553			#endif
554			{ /* ordinary definition */
555			ep = getdefn();
556	greg	1.13	qname = qualname(dname(ep), 0);
557	greg	2.4	#ifdef REDEFW
558	greg	1.16	if ((vdef = varlookup(qname)) != NULL)
559	greg	2.7	if (vdef->def != NULL && epcmp(ep, vdef->def)) {
560	greg	1.16	wputs(qname);
561			if (vdef->def->type == ':')
562			wputs(": redefined constant expression\n");
563			else
564			wputs(": redefined\n");
565			}
566	greg	2.4	#ifdef FUNCTION
567	greg	1.16	else if (ep->v.kid->type == FUNC && vdef->lib != NULL) {
568			wputs(qname);
569			wputs(": definition hides library function\n");
570			}
571	greg	1.8	#endif
572	greg	1.2	#endif
573	greg	1.10	if (ep->type == ':')
574	greg	1.13	dremove(qname);
575	greg	1.10	else
576	greg	1.13	dclear(qname);
577			dpush(qname, ep);
578	greg	1.1	}
579			if (nextc != EOF) {
580			if (nextc != ';')
581			syntax("';' expected");
582			scan();
583			}
584			}
585
586
587			EPNODE *
588			getdefn() /* A -> SYM = E1 */
589	greg	1.8	/* SYM : E1 */
590	greg	2.4	/* FUNC(SYM,..) = E1 */
591	greg	1.8	/* FUNC(SYM,..) : E1 */
592	greg	1.1	{
593			register EPNODE ep1, ep2;
594
595	greg	1.18	if (!isalpha(nextc) && nextc != CNTXMARK)
596	greg	1.1	syntax("illegal variable name");
597
598			ep1 = newnode();
599			ep1->type = SYM;
600			ep1->v.name = savestr(getname());
601
602	greg	2.4	#ifdef FUNCTION
603	greg	1.1	if (nextc == '(') {
604			ep2 = newnode();
605			ep2->type = FUNC;
606			addekid(ep2, ep1);
607			ep1 = ep2;
608			do {
609			scan();
610			if (!isalpha(nextc))
611			syntax("illegal variable name");
612			ep2 = newnode();
613			ep2->type = SYM;
614			ep2->v.name = savestr(getname());
615			addekid(ep1, ep2);
616			} while (nextc == ',');
617			if (nextc != ')')
618			syntax("')' expected");
619			scan();
620			curfunc = ep1;
621			} else
622			curfunc = NULL;
623			#endif
624
625	greg	1.8	if (nextc != '=' && nextc != ':')
626			syntax("'=' or ':' expected");
627	greg	1.1
628			ep2 = newnode();
629	greg	1.8	ep2->type = nextc;
630			scan();
631	greg	1.1	addekid(ep2, ep1);
632			addekid(ep2, getE1());
633
634	greg	1.7	if (
635	greg	2.4	#ifdef FUNCTION
636			ep1->type == SYM &&
637	greg	1.1	#endif
638	greg	1.7	ep1->sibling->type != NUM) {
639	greg	1.1	ep1 = newnode();
640			ep1->type = TICK;
641	greg	2.8	ep1->v.tick = 0;
642	greg	1.1	addekid(ep2, ep1);
643			ep1 = newnode();
644			ep1->type = NUM;
645			addekid(ep2, ep1);
646			}
647
648			return(ep2);
649			}
650
651
652	greg	2.4	#ifdef OUTCHAN
653	greg	1.1	EPNODE *
654			getchan() /* A -> $N = E1 */
655			{
656			register EPNODE ep1, ep2;
657
658			if (nextc != '$')
659			syntax("missing '$'");
660			scan();
661
662			ep1 = newnode();
663			ep1->type = CHAN;
664			ep1->v.chan = getinum();
665
666			if (nextc != '=')
667			syntax("'=' expected");
668			scan();
669
670			ep2 = newnode();
671			ep2->type = '=';
672			addekid(ep2, ep1);
673			addekid(ep2, getE1());
674
675			return(ep2);
676			}
677			#endif
678
679
680
681			/*
682			* The following routines are for internal use only:
683			*/
684
685
686			static double
687			dvalue(name, d) /* evaluate a variable */
688			char *name;
689	greg	2.4	EPNODE *d;
690	greg	1.1	{
691			register EPNODE ep1, ep2;
692
693			if (d == NULL \|\| d->v.kid->type != SYM) {
694			eputs(name);
695			eputs(": undefined variable\n");
696			quit(1);
697			}
698			ep1 = d->v.kid->sibling; /* get expression */
699	greg	1.5	if (ep1->type == NUM)
700			return(ep1->v.num); /* return if number */
701	greg	1.1	ep2 = ep1->sibling; /* check time */
702	greg	2.8	if (ep2->v.tick == 0 \|\| ep2->v.tick < eclock) {
703			ep2->v.tick = d->type == ':' ? ~0L : eclock;
704	greg	1.1	ep2 = ep2->sibling;
705	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
706	greg	1.1	} else
707	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
708	greg	1.1
709			return(ep2->v.num);
710			}