src/common/caldefn.c

#ifndef lint
static const char       RCSid[] = "$Id: caldefn.c,v 2.16 2003/06/07 12:50:20 schorsch Exp $";
#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(                       /* 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(               /* get definitions from a string */
        char  *str,
        char  *fn,
        int  ln
)
{
    initstr(str, fn, ln);
    while (nextc != EOF)
        getstatement();
}


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


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

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


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

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


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

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


char *
setcontext(                     /* 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(            /* push on another context */
        char  *ctx
)
{
    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(void)                        /* 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(               /* get qualified name */
        register char  *nam,
        int  lvl
)
{
    static char  nambuf[RMAXWORD+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+RMAXWORD)
                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+RMAXWORD)
            goto toolong;
        *cp++ = *cpp++;
    }
toolong:
    *cp = '\0';
    return(nambuf);             /* return qualified name */
}


int
incontext(                      /* 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(                        /* set output channels */
        void  (*cs)(int n, double v)
)
{
    register EPNODE  *ep;

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

}


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


VARDEF *
varlookup(                      /* 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(                      /* 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(                      /* 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(                                /* 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(void)                    /* return pointer to first definition */
{
    htndx = 0;
    htpos = NULL;
    ochpos = outchan;
    return(dnext());
}


EPNODE *
dnext(void)                             /* 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(                   /* 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(                  /* push on a definition */
        char  *nm,
        register EPNODE  *ep
)
{
    register VARDEF  *vp;

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


void
addchan(                        /* 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(void)                      /* 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(void)
        /* 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(void)                   /* 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(                 /* 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:	2.17
Committed:	Thu Jul 3 22:41:44 2003 UTC (20 years, 9 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.16:	+4 -4 lines
Log Message:	Reduced compile problems on Windows.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.17	static const char RCSid[] = "$Id: caldefn.c,v 2.16 2003/06/07 12:50:20 schorsch Exp $";
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	schorsch	2.16	fcompile( /* get definitions from a file */
70			char *fname
71			)
72	greg	1.1	{
73			FILE *fp;
74
75			if (fname == NULL)
76			fp = stdin;
77			else if ((fp = fopen(fname, "r")) == NULL) {
78			eputs(fname);
79			eputs(": cannot open\n");
80			quit(1);
81			}
82	greg	1.4	initfile(fp, fname, 0);
83	greg	1.1	while (nextc != EOF)
84	greg	1.13	getstatement();
85	greg	1.1	if (fname != NULL)
86			fclose(fp);
87			}
88
89
90	greg	2.12	void
91	schorsch	2.16	scompile( /* get definitions from a string */
92			char *str,
93			char *fn,
94			int ln
95			)
96	greg	1.1	{
97	greg	1.4	initstr(str, fn, ln);
98	greg	1.1	while (nextc != EOF)
99	greg	1.13	getstatement();
100	greg	1.1	}
101
102
103			double
104	schorsch	2.16	varvalue( /* return a variable's value */
105			char *vname
106			)
107	greg	1.1	{
108			return(dvalue(vname, dlookup(vname)));
109			}
110
111
112			double
113	schorsch	2.16	evariable( /* evaluate a variable */
114			EPNODE *ep
115			)
116	greg	1.1	{
117			register VARDEF *dp = ep->v.ln;
118
119			return(dvalue(dp->name, dp->def));
120			}
121
122
123	greg	2.12	void
124	schorsch	2.16	varset( /* set a variable's value */
125			char *vname,
126			int assign,
127			double val
128			)
129	greg	1.1	{
130	greg	1.13	char *qname;
131	greg	1.1	register EPNODE ep1, ep2;
132	greg	1.13	/* get qualified name */
133			qname = qualname(vname, 0);
134	greg	1.1	/* check for quick set */
135	greg	1.13	if ((ep1 = dlookup(qname)) != NULL && ep1->v.kid->type == SYM) {
136	greg	1.1	ep2 = ep1->v.kid->sibling;
137			if (ep2->type == NUM) {
138			ep2->v.num = val;
139	greg	1.8	ep1->type = assign;
140	greg	1.1	return;
141			}
142			}
143			/* hand build definition */
144			ep1 = newnode();
145	greg	1.8	ep1->type = assign;
146	greg	1.1	ep2 = newnode();
147			ep2->type = SYM;
148			ep2->v.name = savestr(vname);
149			addekid(ep1, ep2);
150			ep2 = newnode();
151			ep2->type = NUM;
152			ep2->v.num = val;
153			addekid(ep1, ep2);
154	greg	1.13	dremove(qname);
155			dpush(qname, ep1);
156	greg	1.1	}
157
158
159	greg	2.12	void
160	schorsch	2.16	dclear( /* delete variable definitions of name */
161			char *name
162			)
163	greg	1.1	{
164			register EPNODE *ep;
165
166	greg	1.8	while ((ep = dpop(name)) != NULL) {
167			if (ep->type == ':') {
168	greg	1.13	dpush(name, ep); /* don't clear constants */
169	greg	1.8	return;
170			}
171			epfree(ep);
172			}
173			}
174
175
176	greg	2.12	void
177	schorsch	2.16	dremove( /* delete all definitions of name */
178			char *name
179			)
180	greg	1.8	{
181			register EPNODE *ep;
182
183	greg	1.1	while ((ep = dpop(name)) != NULL)
184			epfree(ep);
185			}
186
187
188	greg	2.12	int
189	schorsch	2.16	vardefined( /* return non-zero if variable defined */
190			char *name
191			)
192	greg	1.1	{
193			register EPNODE *dp;
194
195			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
196			}
197
198
199	greg	1.13	char *
200	schorsch	2.16	setcontext( /* set a new context path */
201			register char *ctx
202			)
203	greg	1.13	{
204			register char *cpp;
205
206			if (ctx == NULL)
207			return(context); /* just asking */
208	greg	2.6	while (*ctx == CNTXMARK)
209			ctx++; /* skip past marks */
210	greg	1.13	if (!*ctx) {
211	greg	2.6	context[0] = '\0'; /* empty means clear context */
212	greg	1.13	return(context);
213			}
214	greg	2.6	cpp = context; /* start context with mark */
215			*cpp++ = CNTXMARK;
216			do { /* carefully copy new context */
217	greg	2.11	if (cpp >= context+MAXCNTX)
218	greg	1.18	break; /* just copy what we can */
219	greg	1.13	if (isid(*ctx))
220			cpp++ = ctx++;
221			else {
222			*cpp++ = '_'; ctx++;
223			}
224			} while (*ctx);
225	greg	2.6	while (cpp[-1] == CNTXMARK) /* cannot end in context mark */
226			cpp--;
227	greg	1.13	*cpp = '\0';
228	greg	2.6	return(context);
229			}
230
231
232			char *
233	schorsch	2.16	pushcontext( /* push on another context */
234			char *ctx
235			)
236	greg	2.6	{
237	greg	2.11	char oldcontext[MAXCNTX+1];
238	greg	2.6	register int n;
239
240			strcpy(oldcontext, context); /* save old context */
241			setcontext(ctx); /* set new context */
242			n = strlen(context); /* tack on old */
243	greg	2.11	if (n+strlen(oldcontext) > MAXCNTX) {
244			strncpy(context+n, oldcontext, MAXCNTX-n);
245			context[MAXCNTX] = '\0';
246	greg	2.6	} else
247			strcpy(context+n, oldcontext);
248			return(context);
249			}
250
251
252			char *
253	schorsch	2.16	popcontext(void) /* pop off top context */
254	greg	2.6	{
255			register char cp1, cp2;
256
257			if (!context[0]) /* nothing left to pop */
258			return(context);
259			cp2 = context; /* find mark */
260			while (++cp2 && cp2 != CNTXMARK)
261			;
262			cp1 = context; /* copy tail to front */
263			while (cp1++ = cp2++)
264			;
265	greg	1.13	return(context);
266			}
267
268
269			char *
270	schorsch	2.16	qualname( /* get qualified name */
271			register char *nam,
272			int lvl
273			)
274	greg	1.13	{
275	schorsch	2.17	static char nambuf[RMAXWORD+1];
276	greg	1.17	register char cp = nambuf, cpp;
277			/* check for explicit local */
278	greg	1.15	if (*nam == CNTXMARK)
279	greg	1.17	if (lvl > 0) /* only action is to refuse search */
280			return(NULL);
281			else
282			nam++;
283			else if (nam == nambuf) /* check for repeat call */
284			return(lvl > 0 ? NULL : nam);
285	greg	1.13	/* copy name to static buffer */
286			while (*nam) {
287	schorsch	2.17	if (cp >= nambuf+RMAXWORD)
288	greg	1.13	goto toolong;
289	greg	1.17	cp++ = nam++;
290	greg	1.13	}
291	greg	1.17	/* check for explicit global */
292			if (cp > nambuf && cp[-1] == CNTXMARK) {
293	greg	1.13	if (lvl > 0)
294	greg	1.17	return(NULL);
295			*--cp = '\0';
296			return(nambuf); /* already qualified */
297			}
298			cpp = context; /* else skip the requested levels */
299			while (lvl-- > 0) {
300			if (!*cpp)
301			return(NULL); /* return NULL if past global level */
302			while (++cpp && cpp != CNTXMARK)
303			;
304			}
305	greg	1.13	while (cpp) { / copy context to static buffer */
306	schorsch	2.17	if (cp >= nambuf+RMAXWORD)
307	greg	1.13	goto toolong;
308			cp++ = cpp++;
309			}
310	greg	1.18	toolong:
311	greg	1.13	*cp = '\0';
312			return(nambuf); /* return qualified name */
313			}
314
315
316	greg	2.12	int
317	schorsch	2.16	incontext( /* is qualified name in current context? */
318			register char *qn
319			)
320	greg	1.14	{
321	greg	2.9	if (!context[0]) /* global context accepts all */
322			return(1);
323	greg	1.14	while (qn && qn != CNTXMARK) /* find context mark */
324	greg	1.19	qn++;
325	greg	1.14	return(!strcmp(qn, context));
326			}
327
328
329	greg	2.12	void
330	schorsch	2.16	chanout( /* set output channels */
331			void (*cs)(int n, double v)
332			)
333	greg	1.1	{
334			register EPNODE *ep;
335
336			for (ep = outchan; ep != NULL; ep = ep->sibling)
337	greg	1.6	(*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
338	greg	1.1
339			}
340
341
342	greg	2.12	void
343	schorsch	2.16	dcleanup( /* clear definitions (0->vars,1->output,2->consts) */
344			int lvl
345			)
346	greg	1.1	{
347			register int i;
348			register VARDEF *vp;
349			register EPNODE *ep;
350	greg	1.14	/* if context is global, clear all */
351	greg	1.1	for (i = 0; i < NHASH; i++)
352			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
353	greg	2.9	if (incontext(vp->name))
354	greg	1.14	if (lvl >= 2)
355			dremove(vp->name);
356			else
357			dclear(vp->name);
358	greg	1.12	if (lvl >= 1) {
359	greg	1.9	for (ep = outchan; ep != NULL; ep = ep->sibling)
360			epfree(ep);
361			outchan = NULL;
362			}
363	greg	1.1	}
364
365
366			EPNODE *
367	schorsch	2.16	dlookup( /* look up a definition */
368			char *name
369			)
370	greg	1.1	{
371			register VARDEF *vp;
372
373			if ((vp = varlookup(name)) == NULL)
374	greg	2.4	return(NULL);
375	greg	1.1	return(vp->def);
376			}
377
378
379			VARDEF *
380	schorsch	2.16	varlookup( /* look up a variable */
381			char *name
382			)
383	greg	1.1	{
384	greg	2.4	int lvl = 0;
385	greg	1.13	register char *qname;
386	greg	1.1	register VARDEF *vp;
387	greg	2.4	/* find most qualified match */
388	greg	1.13	while ((qname = qualname(name, lvl++)) != NULL)
389			for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
390			if (!strcmp(vp->name, qname))
391			return(vp);
392	greg	1.1	return(NULL);
393			}
394
395
396			VARDEF *
397	schorsch	2.16	varinsert( /* get a link to a variable */
398			char *name
399			)
400	greg	1.1	{
401			register VARDEF *vp;
402	greg	2.4	int hv;
403	greg	1.1
404	greg	1.13	if ((vp = varlookup(name)) != NULL) {
405			vp->nlinks++;
406			return(vp);
407			}
408	greg	2.3	vp = (VARDEF *)emalloc(sizeof(VARDEF));
409			vp->lib = liblookup(name);
410			if (vp->lib == NULL) /* if name not in library */
411	greg	1.16	name = qualname(name, 0); /* use fully qualified version */
412	greg	1.1	hv = hash(name);
413			vp->name = savestr(name);
414			vp->nlinks = 1;
415			vp->def = NULL;
416			vp->next = hashtbl[hv];
417			hashtbl[hv] = vp;
418			return(vp);
419			}
420	greg	2.2
421
422	greg	2.12	void
423	schorsch	2.16	libupdate( /* update library links */
424			char *fn
425			)
426	greg	2.2	{
427			register int i;
428			register VARDEF *vp;
429			/* if fn is NULL then relink all */
430			for (i = 0; i < NHASH; i++)
431			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
432			if (vp->lib != NULL \|\| fn == NULL \|\| !strcmp(fn, vp->name))
433			vp->lib = liblookup(vp->name);
434			}
435	greg	1.1
436
437	greg	2.12	void
438	schorsch	2.16	varfree( /* release link to variable */
439			register VARDEF *ln
440			)
441	greg	1.1	{
442			register VARDEF *vp;
443	greg	2.4	int hv;
444	greg	1.1
445			if (--ln->nlinks > 0)
446	greg	2.4	return; /* still active */
447	greg	1.1
448			hv = hash(ln->name);
449			vp = hashtbl[hv];
450			if (vp == ln)
451	greg	2.4	hashtbl[hv] = vp->next;
452	greg	1.1	else {
453	greg	2.4	while (vp->next != ln) /* must be in list */
454			vp = vp->next;
455			vp->next = ln->next;
456	greg	1.1	}
457			freestr(ln->name);
458			efree((char *)ln);
459			}
460
461
462			EPNODE *
463	schorsch	2.16	dfirst(void) /* return pointer to first definition */
464	greg	1.1	{
465			htndx = 0;
466			htpos = NULL;
467			ochpos = outchan;
468			return(dnext());
469			}
470
471
472			EPNODE *
473	schorsch	2.16	dnext(void) /* return pointer to next definition */
474	greg	1.1	{
475			register EPNODE *ep;
476	greg	1.19	register char *nm;
477	greg	1.1
478			while (htndx < NHASH) {
479	greg	2.4	if (htpos == NULL)
480			htpos = hashtbl[htndx++];
481			while (htpos != NULL) {
482			ep = htpos->def;
483	greg	1.19	nm = htpos->name;
484	greg	2.4	htpos = htpos->next;
485			if (ep != NULL && incontext(nm))
486			return(ep);
487			}
488	greg	1.1	}
489			if ((ep = ochpos) != NULL)
490	greg	2.4	ochpos = ep->sibling;
491	greg	1.1	return(ep);
492			}
493
494
495			EPNODE *
496	schorsch	2.16	dpop( /* pop a definition */
497			char *name
498			)
499	greg	1.1	{
500			register VARDEF *vp;
501			register EPNODE *dp;
502
503			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
504	greg	2.4	return(NULL);
505	greg	1.1	dp = vp->def;
506			vp->def = dp->sibling;
507			varfree(vp);
508			return(dp);
509			}
510
511
512	greg	2.12	void
513	schorsch	2.16	dpush( /* push on a definition */
514			char *nm,
515			register EPNODE *ep
516			)
517	greg	1.1	{
518			register VARDEF *vp;
519
520	greg	1.13	vp = varinsert(nm);
521	greg	1.1	ep->sibling = vp->def;
522			vp->def = ep;
523			}
524
525
526	greg	2.12	void
527	schorsch	2.16	addchan( /* add an output channel assignment */
528			EPNODE *sp
529			)
530	greg	1.1	{
531	greg	2.4	int ch = sp->v.kid->v.chan;
532	greg	1.1	register EPNODE ep, epl;
533
534			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
535			if (ep->v.kid->v.chan >= ch) {
536			if (epl != NULL)
537			epl->sibling = sp;
538			else
539			outchan = sp;
540			if (ep->v.kid->v.chan > ch)
541			sp->sibling = ep;
542			else {
543			sp->sibling = ep->sibling;
544			epfree(ep);
545			}
546			return;
547			}
548			if (epl != NULL)
549			epl->sibling = sp;
550			else
551			outchan = sp;
552			sp->sibling = NULL;
553
554			}
555
556
557	greg	2.12	void
558	schorsch	2.16	getstatement(void) /* get next statement */
559	greg	1.1	{
560			register EPNODE *ep;
561	greg	1.13	char *qname;
562	greg	1.16	register VARDEF *vdef;
563	greg	1.1
564			if (nextc == ';') { /* empty statement */
565			scan();
566			return;
567			}
568	greg	2.12	if (esupport&E_OUTCHAN &&
569			nextc == '$') { /* channel assignment */
570	greg	1.1	ep = getchan();
571			addchan(ep);
572	greg	2.12	} else { /* ordinary definition */
573	greg	1.1	ep = getdefn();
574	greg	1.13	qname = qualname(dname(ep), 0);
575	greg	2.12	if (esupport&E_REDEFW && (vdef = varlookup(qname)) != NULL)
576	greg	2.7	if (vdef->def != NULL && epcmp(ep, vdef->def)) {
577	greg	1.16	wputs(qname);
578			if (vdef->def->type == ':')
579			wputs(": redefined constant expression\n");
580			else
581			wputs(": redefined\n");
582	greg	2.12	} else if (ep->v.kid->type == FUNC && vdef->lib != NULL) {
583	greg	1.16	wputs(qname);
584			wputs(": definition hides library function\n");
585			}
586	greg	1.10	if (ep->type == ':')
587	greg	1.13	dremove(qname);
588	greg	1.10	else
589	greg	1.13	dclear(qname);
590			dpush(qname, ep);
591	greg	1.1	}
592			if (nextc != EOF) {
593			if (nextc != ';')
594			syntax("';' expected");
595			scan();
596			}
597			}
598
599
600			EPNODE *
601	schorsch	2.16	getdefn(void)
602			/* A -> SYM = E1 */
603			/* SYM : E1 */
604			/* FUNC(SYM,..) = E1 */
605			/* FUNC(SYM,..) : E1 */
606	greg	1.1	{
607			register EPNODE ep1, ep2;
608
609	greg	1.18	if (!isalpha(nextc) && nextc != CNTXMARK)
610	greg	1.1	syntax("illegal variable name");
611
612			ep1 = newnode();
613			ep1->type = SYM;
614			ep1->v.name = savestr(getname());
615
616	greg	2.12	if (esupport&E_FUNCTION && nextc == '(') {
617	greg	1.1	ep2 = newnode();
618			ep2->type = FUNC;
619			addekid(ep2, ep1);
620			ep1 = ep2;
621			do {
622			scan();
623			if (!isalpha(nextc))
624			syntax("illegal variable name");
625			ep2 = newnode();
626			ep2->type = SYM;
627			ep2->v.name = savestr(getname());
628			addekid(ep1, ep2);
629			} while (nextc == ',');
630			if (nextc != ')')
631			syntax("')' expected");
632			scan();
633			curfunc = ep1;
634	greg	2.10	}
635	greg	1.1
636	greg	1.8	if (nextc != '=' && nextc != ':')
637			syntax("'=' or ':' expected");
638	greg	1.1
639			ep2 = newnode();
640	greg	1.8	ep2->type = nextc;
641			scan();
642	greg	1.1	addekid(ep2, ep1);
643			addekid(ep2, getE1());
644
645	greg	2.12	if (ep1->type == SYM && ep1->sibling->type != NUM) {
646	greg	1.1	ep1 = newnode();
647			ep1->type = TICK;
648	greg	2.8	ep1->v.tick = 0;
649	greg	1.1	addekid(ep2, ep1);
650			ep1 = newnode();
651			ep1->type = NUM;
652			addekid(ep2, ep1);
653			}
654	greg	2.10	curfunc = NULL;
655	greg	1.1
656			return(ep2);
657			}
658
659
660			EPNODE *
661	schorsch	2.16	getchan(void) /* A -> $N = E1 */
662	greg	1.1	{
663			register EPNODE ep1, ep2;
664
665			if (nextc != '$')
666			syntax("missing '$'");
667			scan();
668
669			ep1 = newnode();
670			ep1->type = CHAN;
671			ep1->v.chan = getinum();
672
673			if (nextc != '=')
674			syntax("'=' expected");
675			scan();
676
677			ep2 = newnode();
678			ep2->type = '=';
679			addekid(ep2, ep1);
680			addekid(ep2, getE1());
681
682			return(ep2);
683			}
684
685
686
687			/*
688			* The following routines are for internal use only:
689			*/
690
691
692			static double
693	schorsch	2.16	dvalue( /* evaluate a variable */
694			char *name,
695			EPNODE *d
696			)
697	greg	1.1	{
698			register EPNODE ep1, ep2;
699
700			if (d == NULL \|\| d->v.kid->type != SYM) {
701			eputs(name);
702			eputs(": undefined variable\n");
703			quit(1);
704			}
705			ep1 = d->v.kid->sibling; /* get expression */
706	greg	1.5	if (ep1->type == NUM)
707			return(ep1->v.num); /* return if number */
708	greg	1.1	ep2 = ep1->sibling; /* check time */
709	greg	2.12	if (eclock >= MAXCLOCK)
710			eclock = 1; /* wrap clock counter */
711			if (ep2->v.tick < MAXCLOCK &&
712			ep2->v.tick == 0 \| ep2->v.tick != eclock) {
713			ep2->v.tick = d->type == ':' ? MAXCLOCK : eclock;
714	greg	1.1	ep2 = ep2->sibling;
715	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
716	greg	1.1	} else
717	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
718	greg	1.1
719			return(ep2->v.num);
720			}