src/common/caldefn.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#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
 *
 *  5/17/2001  Fixed clock counter wrapping behavior
 *
 *  2/19/03     Eliminated conditional compiles in favor of esupport extern.
 */

#include "copyright.h"

#include  <stdio.h>

#include  <string.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))

static double  dvalue();

#define  MAXCLOCK       (1L<<31)        /* clock wrap value */

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

#define  MAXCNTX        1023            /* maximum context length */

static char  context[MAXCNTX+1];        /* current context path */

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

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


void
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);
}


void
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));
}


void
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);
}


void
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);
    }
}


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

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


int
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+MAXCNTX)
            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[MAXCNTX+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) > MAXCNTX) {
        strncpy(context+n, oldcontext, MAXCNTX-n);
        context[MAXCNTX] = '\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 */
}


int
incontext(qn)                   /* is qualified name in current context? */
register char  *qn;
{
    if (!context[0])                    /* global context accepts all */
        return(1);
    while (*qn && *qn != CNTXMARK)      /* find context mark */
        qn++;
    return(!strcmp(qn, context));
}


void
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));

}


void
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 (incontext(vp->name))
                if (lvl >= 2)
                    dremove(vp->name);
                else
                    dclear(vp->name);
    if (lvl >= 1) {
        for (ep = outchan; ep != NULL; ep = ep->sibling)
            epfree(ep);
        outchan = NULL;
    }
}


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));
    vp->lib = liblookup(name);
    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);
}


void
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);
}


void
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;
    ochpos = outchan;
    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);
        }
    }
    if ((ep = ochpos) != NULL)
        ochpos = ep->sibling;
    return(ep);
}


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);
}


void
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;
}


void
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;

}


void
getstatement()                  /* get next statement */
{
    register EPNODE  *ep;
    char  *qname;
    register VARDEF  *vdef;

    if (nextc == ';') {         /* empty statement */
        scan();
        return;
    }
    if (esupport&E_OUTCHAN &&
                nextc == '$') {         /* channel assignment */
        ep = getchan();
        addchan(ep);
    } else {                            /* ordinary definition */
        ep = getdefn();
        qname = qualname(dname(ep), 0);
        if (esupport&E_REDEFW && (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");
            } else if (ep->v.kid->type == FUNC && vdef->lib != NULL) {
                wputs(qname);
                wputs(": definition hides library function\n");
            }
        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());

    if (esupport&E_FUNCTION && 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;
    }

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

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

    if (ep1->type == SYM && ep1->sibling->type != NUM) {
        ep1 = newnode();
        ep1->type = TICK;
        ep1->v.tick = 0;
        addekid(ep2, ep1);
        ep1 = newnode();
        ep1->type = NUM;
        addekid(ep2, ep1);
    }
    curfunc = NULL;

    return(ep2);
}


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);
}


/*
 *  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 (eclock >= MAXCLOCK)
        eclock = 1;                             /* wrap clock counter */
    if (ep2->v.tick < MAXCLOCK &&
                ep2->v.tick == 0 | ep2->v.tick != eclock) {
        ep2->v.tick = d->type == ':' ? MAXCLOCK : 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:	2.13
Committed:	Tue Feb 25 02:47:21 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.12:	+1 -56 lines
Log Message:	Replaced inline copyright notice with #include "copyright.h"
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.12	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5			* Store variable definitions.
6			*
7			* 7/1/85 Greg Ward
8			*
9			* 11/11/85 Added conditional compiles (OUTCHAN) for control output.
10			*
11			* 4/2/86 Added conditional compiles for function definitions (FUNCTION).
12			*
13			* 1/15/88 Added clock for caching of variable values.
14			*
15			* 11/16/88 Added VARDEF structure for hard linking.
16	greg	1.2	*
17			* 5/31/90 Added conditional compile (REDEFW) for redefinition warning.
18	greg	1.8	*
19	greg	1.10	* 4/23/91 Added ':' assignment for constant expressions
20	greg	1.13	*
21			* 8/7/91 Added optional context path to append to variable names
22	greg	2.12	*
23			* 5/17/2001 Fixed clock counter wrapping behavior
24			*
25			* 2/19/03 Eliminated conditional compiles in favor of esupport extern.
26			*/
27
28	greg	2.13	#include "copyright.h"
29	greg	1.1
30			#include <stdio.h>
31
32	greg	2.12	#include <string.h>
33
34	greg	1.1	#include <ctype.h>
35
36			#include "calcomp.h"
37
38	greg	2.4	#ifndef NHASH
39			#define NHASH 521 /* hash size (a prime!) */
40	greg	1.1	#endif
41
42	greg	2.5	#define hash(s) (shash(s)%NHASH)
43
44	greg	2.4	#define newnode() (EPNODE *)ecalloc(1, sizeof(EPNODE))
45	greg	1.1
46	greg	2.12	static double dvalue();
47	greg	1.1
48	greg	2.12	#define MAXCLOCK (1L<<31) /* clock wrap value */
49	greg	1.1
50	greg	2.8	unsigned long eclock = 0; /* value storage timer */
51	greg	1.1
52	greg	2.11	#define MAXCNTX 1023 /* maximum context length */
53	greg	1.13
54	greg	2.11	static char context[MAXCNTX+1]; /* current context path */
55
56	greg	1.1	static VARDEF hashtbl[NHASH]; / definition list */
57			static int htndx; /* index for */
58			static VARDEF htpos; / ...dfirst() and */
59			static EPNODE ochpos; / ...dnext */
60			static EPNODE *outchan;
61
62	greg	2.10	EPNODE *curfunc = NULL;
63	greg	2.4	#define dname(ep) ((ep)->v.kid->type == SYM ? \
64	greg	1.1	(ep)->v.kid->v.name : \
65			(ep)->v.kid->v.kid->v.name)
66
67
68	greg	2.12	void
69	greg	1.1	fcompile(fname) /* get definitions from a file */
70			char *fname;
71			{
72			FILE *fp;
73
74			if (fname == NULL)
75			fp = stdin;
76			else if ((fp = fopen(fname, "r")) == NULL) {
77			eputs(fname);
78			eputs(": cannot open\n");
79			quit(1);
80			}
81	greg	1.4	initfile(fp, fname, 0);
82	greg	1.1	while (nextc != EOF)
83	greg	1.13	getstatement();
84	greg	1.1	if (fname != NULL)
85			fclose(fp);
86			}
87
88
89	greg	2.12	void
90	greg	1.4	scompile(str, fn, ln) /* get definitions from a string */
91	greg	1.1	char *str;
92	greg	1.4	char *fn;
93			int ln;
94	greg	1.1	{
95	greg	1.4	initstr(str, fn, ln);
96	greg	1.1	while (nextc != EOF)
97	greg	1.13	getstatement();
98	greg	1.1	}
99
100
101			double
102			varvalue(vname) /* return a variable's value */
103			char *vname;
104			{
105			return(dvalue(vname, dlookup(vname)));
106			}
107
108
109			double
110			evariable(ep) /* evaluate a variable */
111	greg	2.4	EPNODE *ep;
112	greg	1.1	{
113			register VARDEF *dp = ep->v.ln;
114
115			return(dvalue(dp->name, dp->def));
116			}
117
118
119	greg	2.12	void
120	greg	1.8	varset(vname, assign, val) /* set a variable's value */
121	greg	1.1	char *vname;
122	greg	1.8	int assign;
123	greg	2.4	double val;
124	greg	1.1	{
125	greg	1.13	char *qname;
126	greg	1.1	register EPNODE ep1, ep2;
127	greg	1.13	/* get qualified name */
128			qname = qualname(vname, 0);
129	greg	1.1	/* check for quick set */
130	greg	1.13	if ((ep1 = dlookup(qname)) != NULL && ep1->v.kid->type == SYM) {
131	greg	1.1	ep2 = ep1->v.kid->sibling;
132			if (ep2->type == NUM) {
133			ep2->v.num = val;
134	greg	1.8	ep1->type = assign;
135	greg	1.1	return;
136			}
137			}
138			/* hand build definition */
139			ep1 = newnode();
140	greg	1.8	ep1->type = assign;
141	greg	1.1	ep2 = newnode();
142			ep2->type = SYM;
143			ep2->v.name = savestr(vname);
144			addekid(ep1, ep2);
145			ep2 = newnode();
146			ep2->type = NUM;
147			ep2->v.num = val;
148			addekid(ep1, ep2);
149	greg	1.13	dremove(qname);
150			dpush(qname, ep1);
151	greg	1.1	}
152
153
154	greg	2.12	void
155	greg	1.8	dclear(name) /* delete variable definitions of name */
156	greg	1.1	char *name;
157			{
158			register EPNODE *ep;
159
160	greg	1.8	while ((ep = dpop(name)) != NULL) {
161			if (ep->type == ':') {
162	greg	1.13	dpush(name, ep); /* don't clear constants */
163	greg	1.8	return;
164			}
165			epfree(ep);
166			}
167			}
168
169
170	greg	2.12	void
171	greg	1.8	dremove(name) /* delete all definitions of name */
172			char *name;
173			{
174			register EPNODE *ep;
175
176	greg	1.1	while ((ep = dpop(name)) != NULL)
177			epfree(ep);
178			}
179
180
181	greg	2.12	int
182	greg	1.1	vardefined(name) /* return non-zero if variable defined */
183			char *name;
184			{
185			register EPNODE *dp;
186
187			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
188			}
189
190
191	greg	1.13	char *
192			setcontext(ctx) /* set a new context path */
193			register char *ctx;
194			{
195			register char *cpp;
196
197			if (ctx == NULL)
198			return(context); /* just asking */
199	greg	2.6	while (*ctx == CNTXMARK)
200			ctx++; /* skip past marks */
201	greg	1.13	if (!*ctx) {
202	greg	2.6	context[0] = '\0'; /* empty means clear context */
203	greg	1.13	return(context);
204			}
205	greg	2.6	cpp = context; /* start context with mark */
206			*cpp++ = CNTXMARK;
207			do { /* carefully copy new context */
208	greg	2.11	if (cpp >= context+MAXCNTX)
209	greg	1.18	break; /* just copy what we can */
210	greg	1.13	if (isid(*ctx))
211			cpp++ = ctx++;
212			else {
213			*cpp++ = '_'; ctx++;
214			}
215			} while (*ctx);
216	greg	2.6	while (cpp[-1] == CNTXMARK) /* cannot end in context mark */
217			cpp--;
218	greg	1.13	*cpp = '\0';
219	greg	2.6	return(context);
220			}
221
222
223			char *
224			pushcontext(ctx) /* push on another context */
225			char *ctx;
226			{
227			extern char strncpy(), strcpy();
228	greg	2.11	char oldcontext[MAXCNTX+1];
229	greg	2.6	register int n;
230
231			strcpy(oldcontext, context); /* save old context */
232			setcontext(ctx); /* set new context */
233			n = strlen(context); /* tack on old */
234	greg	2.11	if (n+strlen(oldcontext) > MAXCNTX) {
235			strncpy(context+n, oldcontext, MAXCNTX-n);
236			context[MAXCNTX] = '\0';
237	greg	2.6	} else
238			strcpy(context+n, oldcontext);
239			return(context);
240			}
241
242
243			char *
244			popcontext() /* pop off top context */
245			{
246			register char cp1, cp2;
247
248			if (!context[0]) /* nothing left to pop */
249			return(context);
250			cp2 = context; /* find mark */
251			while (++cp2 && cp2 != CNTXMARK)
252			;
253			cp1 = context; /* copy tail to front */
254			while (cp1++ = cp2++)
255			;
256	greg	1.13	return(context);
257			}
258
259
260			char *
261			qualname(nam, lvl) /* get qualified name */
262			register char *nam;
263			int lvl;
264			{
265	greg	2.4	static char nambuf[MAXWORD+1];
266	greg	1.17	register char cp = nambuf, cpp;
267			/* check for explicit local */
268	greg	1.15	if (*nam == CNTXMARK)
269	greg	1.17	if (lvl > 0) /* only action is to refuse search */
270			return(NULL);
271			else
272			nam++;
273			else if (nam == nambuf) /* check for repeat call */
274			return(lvl > 0 ? NULL : nam);
275	greg	1.13	/* copy name to static buffer */
276			while (*nam) {
277	greg	1.18	if (cp >= nambuf+MAXWORD)
278	greg	1.13	goto toolong;
279	greg	1.17	cp++ = nam++;
280	greg	1.13	}
281	greg	1.17	/* check for explicit global */
282			if (cp > nambuf && cp[-1] == CNTXMARK) {
283	greg	1.13	if (lvl > 0)
284	greg	1.17	return(NULL);
285			*--cp = '\0';
286			return(nambuf); /* already qualified */
287			}
288			cpp = context; /* else skip the requested levels */
289			while (lvl-- > 0) {
290			if (!*cpp)
291			return(NULL); /* return NULL if past global level */
292			while (++cpp && cpp != CNTXMARK)
293			;
294			}
295	greg	1.13	while (cpp) { / copy context to static buffer */
296	greg	1.18	if (cp >= nambuf+MAXWORD)
297	greg	1.13	goto toolong;
298			cp++ = cpp++;
299			}
300	greg	1.18	toolong:
301	greg	1.13	*cp = '\0';
302			return(nambuf); /* return qualified name */
303			}
304
305
306	greg	2.12	int
307	greg	1.14	incontext(qn) /* is qualified name in current context? */
308			register char *qn;
309			{
310	greg	2.9	if (!context[0]) /* global context accepts all */
311			return(1);
312	greg	1.14	while (qn && qn != CNTXMARK) /* find context mark */
313	greg	1.19	qn++;
314	greg	1.14	return(!strcmp(qn, context));
315			}
316
317
318	greg	2.12	void
319	greg	1.6	chanout(cs) /* set output channels */
320			int (*cs)();
321	greg	1.1	{
322			register EPNODE *ep;
323
324			for (ep = outchan; ep != NULL; ep = ep->sibling)
325	greg	1.6	(*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
326	greg	1.1
327			}
328
329
330	greg	2.12	void
331	greg	1.12	dcleanup(lvl) /* clear definitions (0->vars,1->output,2->consts) */
332	greg	1.10	int lvl;
333	greg	1.1	{
334			register int i;
335			register VARDEF *vp;
336			register EPNODE *ep;
337	greg	1.14	/* if context is global, clear all */
338	greg	1.1	for (i = 0; i < NHASH; i++)
339			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
340	greg	2.9	if (incontext(vp->name))
341	greg	1.14	if (lvl >= 2)
342			dremove(vp->name);
343			else
344			dclear(vp->name);
345	greg	1.12	if (lvl >= 1) {
346	greg	1.9	for (ep = outchan; ep != NULL; ep = ep->sibling)
347			epfree(ep);
348			outchan = NULL;
349			}
350	greg	1.1	}
351
352
353			EPNODE *
354			dlookup(name) /* look up a definition */
355			char *name;
356			{
357			register VARDEF *vp;
358
359			if ((vp = varlookup(name)) == NULL)
360	greg	2.4	return(NULL);
361	greg	1.1	return(vp->def);
362			}
363
364
365			VARDEF *
366			varlookup(name) /* look up a variable */
367			char *name;
368			{
369	greg	2.4	int lvl = 0;
370	greg	1.13	register char *qname;
371	greg	1.1	register VARDEF *vp;
372	greg	2.4	/* find most qualified match */
373	greg	1.13	while ((qname = qualname(name, lvl++)) != NULL)
374			for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
375			if (!strcmp(vp->name, qname))
376			return(vp);
377	greg	1.1	return(NULL);
378			}
379
380
381			VARDEF *
382			varinsert(name) /* get a link to a variable */
383			char *name;
384			{
385			register VARDEF *vp;
386	greg	2.4	int hv;
387	greg	1.1
388	greg	1.13	if ((vp = varlookup(name)) != NULL) {
389			vp->nlinks++;
390			return(vp);
391			}
392	greg	2.3	vp = (VARDEF *)emalloc(sizeof(VARDEF));
393			vp->lib = liblookup(name);
394			if (vp->lib == NULL) /* if name not in library */
395	greg	1.16	name = qualname(name, 0); /* use fully qualified version */
396	greg	1.1	hv = hash(name);
397			vp->name = savestr(name);
398			vp->nlinks = 1;
399			vp->def = NULL;
400			vp->next = hashtbl[hv];
401			hashtbl[hv] = vp;
402			return(vp);
403			}
404	greg	2.2
405
406	greg	2.12	void
407	greg	2.2	libupdate(fn) /* update library links */
408			char *fn;
409			{
410			register int i;
411			register VARDEF *vp;
412			/* if fn is NULL then relink all */
413			for (i = 0; i < NHASH; i++)
414			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
415			if (vp->lib != NULL \|\| fn == NULL \|\| !strcmp(fn, vp->name))
416			vp->lib = liblookup(vp->name);
417			}
418	greg	1.1
419
420	greg	2.12	void
421	greg	1.1	varfree(ln) /* release link to variable */
422	greg	2.4	register VARDEF *ln;
423	greg	1.1	{
424			register VARDEF *vp;
425	greg	2.4	int hv;
426	greg	1.1
427			if (--ln->nlinks > 0)
428	greg	2.4	return; /* still active */
429	greg	1.1
430			hv = hash(ln->name);
431			vp = hashtbl[hv];
432			if (vp == ln)
433	greg	2.4	hashtbl[hv] = vp->next;
434	greg	1.1	else {
435	greg	2.4	while (vp->next != ln) /* must be in list */
436			vp = vp->next;
437			vp->next = ln->next;
438	greg	1.1	}
439			freestr(ln->name);
440			efree((char *)ln);
441			}
442
443
444			EPNODE *
445			dfirst() /* return pointer to first definition */
446			{
447			htndx = 0;
448			htpos = NULL;
449			ochpos = outchan;
450			return(dnext());
451			}
452
453
454			EPNODE *
455			dnext() /* return pointer to next definition */
456			{
457			register EPNODE *ep;
458	greg	1.19	register char *nm;
459	greg	1.1
460			while (htndx < NHASH) {
461	greg	2.4	if (htpos == NULL)
462			htpos = hashtbl[htndx++];
463			while (htpos != NULL) {
464			ep = htpos->def;
465	greg	1.19	nm = htpos->name;
466	greg	2.4	htpos = htpos->next;
467			if (ep != NULL && incontext(nm))
468			return(ep);
469			}
470	greg	1.1	}
471			if ((ep = ochpos) != NULL)
472	greg	2.4	ochpos = ep->sibling;
473	greg	1.1	return(ep);
474			}
475
476
477			EPNODE *
478			dpop(name) /* pop a definition */
479			char *name;
480			{
481			register VARDEF *vp;
482			register EPNODE *dp;
483
484			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
485	greg	2.4	return(NULL);
486	greg	1.1	dp = vp->def;
487			vp->def = dp->sibling;
488			varfree(vp);
489			return(dp);
490			}
491
492
493	greg	2.12	void
494	greg	1.13	dpush(nm, ep) /* push on a definition */
495			char *nm;
496	greg	2.4	register EPNODE *ep;
497	greg	1.1	{
498			register VARDEF *vp;
499
500	greg	1.13	vp = varinsert(nm);
501	greg	1.1	ep->sibling = vp->def;
502			vp->def = ep;
503			}
504
505
506	greg	2.12	void
507	greg	1.1	addchan(sp) /* add an output channel assignment */
508	greg	2.4	EPNODE *sp;
509	greg	1.1	{
510	greg	2.4	int ch = sp->v.kid->v.chan;
511	greg	1.1	register EPNODE ep, epl;
512
513			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
514			if (ep->v.kid->v.chan >= ch) {
515			if (epl != NULL)
516			epl->sibling = sp;
517			else
518			outchan = sp;
519			if (ep->v.kid->v.chan > ch)
520			sp->sibling = ep;
521			else {
522			sp->sibling = ep->sibling;
523			epfree(ep);
524			}
525			return;
526			}
527			if (epl != NULL)
528			epl->sibling = sp;
529			else
530			outchan = sp;
531			sp->sibling = NULL;
532
533			}
534
535
536	greg	2.12	void
537	greg	1.13	getstatement() /* get next statement */
538	greg	1.1	{
539			register EPNODE *ep;
540	greg	1.13	char *qname;
541	greg	1.16	register VARDEF *vdef;
542	greg	1.1
543			if (nextc == ';') { /* empty statement */
544			scan();
545			return;
546			}
547	greg	2.12	if (esupport&E_OUTCHAN &&
548			nextc == '$') { /* channel assignment */
549	greg	1.1	ep = getchan();
550			addchan(ep);
551	greg	2.12	} else { /* ordinary definition */
552	greg	1.1	ep = getdefn();
553	greg	1.13	qname = qualname(dname(ep), 0);
554	greg	2.12	if (esupport&E_REDEFW && (vdef = varlookup(qname)) != NULL)
555	greg	2.7	if (vdef->def != NULL && epcmp(ep, vdef->def)) {
556	greg	1.16	wputs(qname);
557			if (vdef->def->type == ':')
558			wputs(": redefined constant expression\n");
559			else
560			wputs(": redefined\n");
561	greg	2.12	} else if (ep->v.kid->type == FUNC && vdef->lib != NULL) {
562	greg	1.16	wputs(qname);
563			wputs(": definition hides library function\n");
564			}
565	greg	1.10	if (ep->type == ':')
566	greg	1.13	dremove(qname);
567	greg	1.10	else
568	greg	1.13	dclear(qname);
569			dpush(qname, ep);
570	greg	1.1	}
571			if (nextc != EOF) {
572			if (nextc != ';')
573			syntax("';' expected");
574			scan();
575			}
576			}
577
578
579			EPNODE *
580			getdefn() /* A -> SYM = E1 */
581	greg	1.8	/* SYM : E1 */
582	greg	2.4	/* FUNC(SYM,..) = E1 */
583	greg	1.8	/* FUNC(SYM,..) : E1 */
584	greg	1.1	{
585			register EPNODE ep1, ep2;
586
587	greg	1.18	if (!isalpha(nextc) && nextc != CNTXMARK)
588	greg	1.1	syntax("illegal variable name");
589
590			ep1 = newnode();
591			ep1->type = SYM;
592			ep1->v.name = savestr(getname());
593
594	greg	2.12	if (esupport&E_FUNCTION && nextc == '(') {
595	greg	1.1	ep2 = newnode();
596			ep2->type = FUNC;
597			addekid(ep2, ep1);
598			ep1 = ep2;
599			do {
600			scan();
601			if (!isalpha(nextc))
602			syntax("illegal variable name");
603			ep2 = newnode();
604			ep2->type = SYM;
605			ep2->v.name = savestr(getname());
606			addekid(ep1, ep2);
607			} while (nextc == ',');
608			if (nextc != ')')
609			syntax("')' expected");
610			scan();
611			curfunc = ep1;
612	greg	2.10	}
613	greg	1.1
614	greg	1.8	if (nextc != '=' && nextc != ':')
615			syntax("'=' or ':' expected");
616	greg	1.1
617			ep2 = newnode();
618	greg	1.8	ep2->type = nextc;
619			scan();
620	greg	1.1	addekid(ep2, ep1);
621			addekid(ep2, getE1());
622
623	greg	2.12	if (ep1->type == SYM && ep1->sibling->type != NUM) {
624	greg	1.1	ep1 = newnode();
625			ep1->type = TICK;
626	greg	2.8	ep1->v.tick = 0;
627	greg	1.1	addekid(ep2, ep1);
628			ep1 = newnode();
629			ep1->type = NUM;
630			addekid(ep2, ep1);
631			}
632	greg	2.10	curfunc = NULL;
633	greg	1.1
634			return(ep2);
635			}
636
637
638			EPNODE *
639			getchan() /* A -> $N = E1 */
640			{
641			register EPNODE ep1, ep2;
642
643			if (nextc != '$')
644			syntax("missing '$'");
645			scan();
646
647			ep1 = newnode();
648			ep1->type = CHAN;
649			ep1->v.chan = getinum();
650
651			if (nextc != '=')
652			syntax("'=' expected");
653			scan();
654
655			ep2 = newnode();
656			ep2->type = '=';
657			addekid(ep2, ep1);
658			addekid(ep2, getE1());
659
660			return(ep2);
661			}
662
663
664
665			/*
666			* The following routines are for internal use only:
667			*/
668
669
670			static double
671			dvalue(name, d) /* evaluate a variable */
672			char *name;
673	greg	2.4	EPNODE *d;
674	greg	1.1	{
675			register EPNODE ep1, ep2;
676
677			if (d == NULL \|\| d->v.kid->type != SYM) {
678			eputs(name);
679			eputs(": undefined variable\n");
680			quit(1);
681			}
682			ep1 = d->v.kid->sibling; /* get expression */
683	greg	1.5	if (ep1->type == NUM)
684			return(ep1->v.num); /* return if number */
685	greg	1.1	ep2 = ep1->sibling; /* check time */
686	greg	2.12	if (eclock >= MAXCLOCK)
687			eclock = 1; /* wrap clock counter */
688			if (ep2->v.tick < MAXCLOCK &&
689			ep2->v.tick == 0 \| ep2->v.tick != eclock) {
690			ep2->v.tick = d->type == ':' ? MAXCLOCK : eclock;
691	greg	1.1	ep2 = ep2->sibling;
692	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
693	greg	1.1	} else
694	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
695	greg	1.1
696			return(ep2->v.num);
697			}