1 |
/* $Header: /cvsroot/esrg/sfesrg/esrgpcpj/shared/tcl_base/tcllink.c,v 1.1.1.1 2001/06/13 04:42:27 dtashley Exp $ */
|
2 |
|
3 |
/*
|
4 |
* tclLink.c --
|
5 |
*
|
6 |
* This file implements linked variables (a C variable that is
|
7 |
* tied to a Tcl variable). The idea of linked variables was
|
8 |
* first suggested by Andreas Stolcke and this implementation is
|
9 |
* based heavily on a prototype implementation provided by
|
10 |
* him.
|
11 |
*
|
12 |
* Copyright (c) 1993 The Regents of the University of California.
|
13 |
* Copyright (c) 1994-1997 Sun Microsystems, Inc.
|
14 |
*
|
15 |
* See the file "license.terms" for information on usage and redistribution
|
16 |
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
17 |
*
|
18 |
* RCS: @(#) $Id: tcllink.c,v 1.1.1.1 2001/06/13 04:42:27 dtashley Exp $
|
19 |
*/
|
20 |
|
21 |
#include "tclInt.h"
|
22 |
|
23 |
/*
|
24 |
* For each linked variable there is a data structure of the following
|
25 |
* type, which describes the link and is the clientData for the trace
|
26 |
* set on the Tcl variable.
|
27 |
*/
|
28 |
|
29 |
typedef struct Link {
|
30 |
Tcl_Interp *interp; /* Interpreter containing Tcl variable. */
|
31 |
char *varName; /* Name of variable (must be global). This
|
32 |
* is needed during trace callbacks, since
|
33 |
* the actual variable may be aliased at
|
34 |
* that time via upvar. */
|
35 |
char *addr; /* Location of C variable. */
|
36 |
int type; /* Type of link (TCL_LINK_INT, etc.). */
|
37 |
union {
|
38 |
int i;
|
39 |
double d;
|
40 |
} lastValue; /* Last known value of C variable; used to
|
41 |
* avoid string conversions. */
|
42 |
int flags; /* Miscellaneous one-bit values; see below
|
43 |
* for definitions. */
|
44 |
} Link;
|
45 |
|
46 |
/*
|
47 |
* Definitions for flag bits:
|
48 |
* LINK_READ_ONLY - 1 means errors should be generated if Tcl
|
49 |
* script attempts to write variable.
|
50 |
* LINK_BEING_UPDATED - 1 means that a call to Tcl_UpdateLinkedVar
|
51 |
* is in progress for this variable, so
|
52 |
* trace callbacks on the variable should
|
53 |
* be ignored.
|
54 |
*/
|
55 |
|
56 |
#define LINK_READ_ONLY 1
|
57 |
#define LINK_BEING_UPDATED 2
|
58 |
|
59 |
/*
|
60 |
* Forward references to procedures defined later in this file:
|
61 |
*/
|
62 |
|
63 |
static char * LinkTraceProc _ANSI_ARGS_((ClientData clientData,
|
64 |
Tcl_Interp *interp, char *name1, char *name2,
|
65 |
int flags));
|
66 |
static char * StringValue _ANSI_ARGS_((Link *linkPtr,
|
67 |
char *buffer));
|
68 |
|
69 |
/*
|
70 |
*----------------------------------------------------------------------
|
71 |
*
|
72 |
* Tcl_LinkVar --
|
73 |
*
|
74 |
* Link a C variable to a Tcl variable so that changes to either
|
75 |
* one causes the other to change.
|
76 |
*
|
77 |
* Results:
|
78 |
* The return value is TCL_OK if everything went well or TCL_ERROR
|
79 |
* if an error occurred (the interp's result is also set after
|
80 |
* errors).
|
81 |
*
|
82 |
* Side effects:
|
83 |
* The value at *addr is linked to the Tcl variable "varName",
|
84 |
* using "type" to convert between string values for Tcl and
|
85 |
* binary values for *addr.
|
86 |
*
|
87 |
*----------------------------------------------------------------------
|
88 |
*/
|
89 |
|
90 |
int
|
91 |
Tcl_LinkVar(interp, varName, addr, type)
|
92 |
Tcl_Interp *interp; /* Interpreter in which varName exists. */
|
93 |
char *varName; /* Name of a global variable in interp. */
|
94 |
char *addr; /* Address of a C variable to be linked
|
95 |
* to varName. */
|
96 |
int type; /* Type of C variable: TCL_LINK_INT, etc.
|
97 |
* Also may have TCL_LINK_READ_ONLY
|
98 |
* OR'ed in. */
|
99 |
{
|
100 |
Link *linkPtr;
|
101 |
char buffer[TCL_DOUBLE_SPACE];
|
102 |
int code;
|
103 |
|
104 |
linkPtr = (Link *) ckalloc(sizeof(Link));
|
105 |
linkPtr->interp = interp;
|
106 |
linkPtr->varName = (char *) ckalloc((unsigned) (strlen(varName) + 1));
|
107 |
strcpy(linkPtr->varName, varName);
|
108 |
linkPtr->addr = addr;
|
109 |
linkPtr->type = type & ~TCL_LINK_READ_ONLY;
|
110 |
if (type & TCL_LINK_READ_ONLY) {
|
111 |
linkPtr->flags = LINK_READ_ONLY;
|
112 |
} else {
|
113 |
linkPtr->flags = 0;
|
114 |
}
|
115 |
if (Tcl_SetVar(interp, varName, StringValue(linkPtr, buffer),
|
116 |
TCL_GLOBAL_ONLY|TCL_LEAVE_ERR_MSG) == NULL) {
|
117 |
ckfree(linkPtr->varName);
|
118 |
ckfree((char *) linkPtr);
|
119 |
return TCL_ERROR;
|
120 |
}
|
121 |
code = Tcl_TraceVar(interp, varName, TCL_GLOBAL_ONLY|TCL_TRACE_READS
|
122 |
|TCL_TRACE_WRITES|TCL_TRACE_UNSETS, LinkTraceProc,
|
123 |
(ClientData) linkPtr);
|
124 |
if (code != TCL_OK) {
|
125 |
ckfree(linkPtr->varName);
|
126 |
ckfree((char *) linkPtr);
|
127 |
}
|
128 |
return code;
|
129 |
}
|
130 |
|
131 |
/*
|
132 |
*----------------------------------------------------------------------
|
133 |
*
|
134 |
* Tcl_UnlinkVar --
|
135 |
*
|
136 |
* Destroy the link between a Tcl variable and a C variable.
|
137 |
*
|
138 |
* Results:
|
139 |
* None.
|
140 |
*
|
141 |
* Side effects:
|
142 |
* If "varName" was previously linked to a C variable, the link
|
143 |
* is broken to make the variable independent. If there was no
|
144 |
* previous link for "varName" then nothing happens.
|
145 |
*
|
146 |
*----------------------------------------------------------------------
|
147 |
*/
|
148 |
|
149 |
void
|
150 |
Tcl_UnlinkVar(interp, varName)
|
151 |
Tcl_Interp *interp; /* Interpreter containing variable to unlink. */
|
152 |
char *varName; /* Global variable in interp to unlink. */
|
153 |
{
|
154 |
Link *linkPtr;
|
155 |
|
156 |
linkPtr = (Link *) Tcl_VarTraceInfo(interp, varName, TCL_GLOBAL_ONLY,
|
157 |
LinkTraceProc, (ClientData) NULL);
|
158 |
if (linkPtr == NULL) {
|
159 |
return;
|
160 |
}
|
161 |
Tcl_UntraceVar(interp, varName,
|
162 |
TCL_GLOBAL_ONLY|TCL_TRACE_READS|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
|
163 |
LinkTraceProc, (ClientData) linkPtr);
|
164 |
ckfree(linkPtr->varName);
|
165 |
ckfree((char *) linkPtr);
|
166 |
}
|
167 |
|
168 |
/*
|
169 |
*----------------------------------------------------------------------
|
170 |
*
|
171 |
* Tcl_UpdateLinkedVar --
|
172 |
*
|
173 |
* This procedure is invoked after a linked variable has been
|
174 |
* changed by C code. It updates the Tcl variable so that
|
175 |
* traces on the variable will trigger.
|
176 |
*
|
177 |
* Results:
|
178 |
* None.
|
179 |
*
|
180 |
* Side effects:
|
181 |
* The Tcl variable "varName" is updated from its C value,
|
182 |
* causing traces on the variable to trigger.
|
183 |
*
|
184 |
*----------------------------------------------------------------------
|
185 |
*/
|
186 |
|
187 |
void
|
188 |
Tcl_UpdateLinkedVar(interp, varName)
|
189 |
Tcl_Interp *interp; /* Interpreter containing variable. */
|
190 |
char *varName; /* Name of global variable that is linked. */
|
191 |
{
|
192 |
Link *linkPtr;
|
193 |
char buffer[TCL_DOUBLE_SPACE];
|
194 |
int savedFlag;
|
195 |
|
196 |
linkPtr = (Link *) Tcl_VarTraceInfo(interp, varName, TCL_GLOBAL_ONLY,
|
197 |
LinkTraceProc, (ClientData) NULL);
|
198 |
if (linkPtr == NULL) {
|
199 |
return;
|
200 |
}
|
201 |
savedFlag = linkPtr->flags & LINK_BEING_UPDATED;
|
202 |
linkPtr->flags |= LINK_BEING_UPDATED;
|
203 |
Tcl_SetVar(interp, linkPtr->varName, StringValue(linkPtr, buffer),
|
204 |
TCL_GLOBAL_ONLY);
|
205 |
linkPtr->flags = (linkPtr->flags & ~LINK_BEING_UPDATED) | savedFlag;
|
206 |
}
|
207 |
|
208 |
/*
|
209 |
*----------------------------------------------------------------------
|
210 |
*
|
211 |
* LinkTraceProc --
|
212 |
*
|
213 |
* This procedure is invoked when a linked Tcl variable is read,
|
214 |
* written, or unset from Tcl. It's responsible for keeping the
|
215 |
* C variable in sync with the Tcl variable.
|
216 |
*
|
217 |
* Results:
|
218 |
* If all goes well, NULL is returned; otherwise an error message
|
219 |
* is returned.
|
220 |
*
|
221 |
* Side effects:
|
222 |
* The C variable may be updated to make it consistent with the
|
223 |
* Tcl variable, or the Tcl variable may be overwritten to reject
|
224 |
* a modification.
|
225 |
*
|
226 |
*----------------------------------------------------------------------
|
227 |
*/
|
228 |
|
229 |
static char *
|
230 |
LinkTraceProc(clientData, interp, name1, name2, flags)
|
231 |
ClientData clientData; /* Contains information about the link. */
|
232 |
Tcl_Interp *interp; /* Interpreter containing Tcl variable. */
|
233 |
char *name1; /* First part of variable name. */
|
234 |
char *name2; /* Second part of variable name. */
|
235 |
int flags; /* Miscellaneous additional information. */
|
236 |
{
|
237 |
Link *linkPtr = (Link *) clientData;
|
238 |
int changed;
|
239 |
char buffer[TCL_DOUBLE_SPACE];
|
240 |
char *value, **pp, *result;
|
241 |
Tcl_Obj *objPtr;
|
242 |
|
243 |
/*
|
244 |
* If the variable is being unset, then just re-create it (with a
|
245 |
* trace) unless the whole interpreter is going away.
|
246 |
*/
|
247 |
|
248 |
if (flags & TCL_TRACE_UNSETS) {
|
249 |
if (flags & TCL_INTERP_DESTROYED) {
|
250 |
ckfree(linkPtr->varName);
|
251 |
ckfree((char *) linkPtr);
|
252 |
} else if (flags & TCL_TRACE_DESTROYED) {
|
253 |
Tcl_SetVar(interp, linkPtr->varName, StringValue(linkPtr, buffer),
|
254 |
TCL_GLOBAL_ONLY);
|
255 |
Tcl_TraceVar(interp, linkPtr->varName, TCL_GLOBAL_ONLY
|
256 |
|TCL_TRACE_READS|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
|
257 |
LinkTraceProc, (ClientData) linkPtr);
|
258 |
}
|
259 |
return NULL;
|
260 |
}
|
261 |
|
262 |
/*
|
263 |
* If we were invoked because of a call to Tcl_UpdateLinkedVar, then
|
264 |
* don't do anything at all. In particular, we don't want to get
|
265 |
* upset that the variable is being modified, even if it is
|
266 |
* supposed to be read-only.
|
267 |
*/
|
268 |
|
269 |
if (linkPtr->flags & LINK_BEING_UPDATED) {
|
270 |
return NULL;
|
271 |
}
|
272 |
|
273 |
/*
|
274 |
* For read accesses, update the Tcl variable if the C variable
|
275 |
* has changed since the last time we updated the Tcl variable.
|
276 |
*/
|
277 |
|
278 |
if (flags & TCL_TRACE_READS) {
|
279 |
switch (linkPtr->type) {
|
280 |
case TCL_LINK_INT:
|
281 |
case TCL_LINK_BOOLEAN:
|
282 |
changed = *(int *)(linkPtr->addr) != linkPtr->lastValue.i;
|
283 |
break;
|
284 |
case TCL_LINK_DOUBLE:
|
285 |
changed = *(double *)(linkPtr->addr) != linkPtr->lastValue.d;
|
286 |
break;
|
287 |
case TCL_LINK_STRING:
|
288 |
changed = 1;
|
289 |
break;
|
290 |
default:
|
291 |
return "internal error: bad linked variable type";
|
292 |
}
|
293 |
if (changed) {
|
294 |
Tcl_SetVar(interp, linkPtr->varName, StringValue(linkPtr, buffer),
|
295 |
TCL_GLOBAL_ONLY);
|
296 |
}
|
297 |
return NULL;
|
298 |
}
|
299 |
|
300 |
/*
|
301 |
* For writes, first make sure that the variable is writable. Then
|
302 |
* convert the Tcl value to C if possible. If the variable isn't
|
303 |
* writable or can't be converted, then restore the varaible's old
|
304 |
* value and return an error. Another tricky thing: we have to save
|
305 |
* and restore the interpreter's result, since the variable access
|
306 |
* could occur when the result has been partially set.
|
307 |
*/
|
308 |
|
309 |
if (linkPtr->flags & LINK_READ_ONLY) {
|
310 |
Tcl_SetVar(interp, linkPtr->varName, StringValue(linkPtr, buffer),
|
311 |
TCL_GLOBAL_ONLY);
|
312 |
return "linked variable is read-only";
|
313 |
}
|
314 |
value = Tcl_GetVar(interp, linkPtr->varName, TCL_GLOBAL_ONLY);
|
315 |
if (value == NULL) {
|
316 |
/*
|
317 |
* This shouldn't ever happen.
|
318 |
*/
|
319 |
return "internal error: linked variable couldn't be read";
|
320 |
}
|
321 |
|
322 |
objPtr = Tcl_GetObjResult(interp);
|
323 |
Tcl_IncrRefCount(objPtr);
|
324 |
Tcl_ResetResult(interp);
|
325 |
result = NULL;
|
326 |
|
327 |
switch (linkPtr->type) {
|
328 |
case TCL_LINK_INT:
|
329 |
if (Tcl_GetInt(interp, value, &linkPtr->lastValue.i) != TCL_OK) {
|
330 |
Tcl_SetObjResult(interp, objPtr);
|
331 |
Tcl_SetVar(interp, linkPtr->varName,
|
332 |
StringValue(linkPtr, buffer), TCL_GLOBAL_ONLY);
|
333 |
result = "variable must have integer value";
|
334 |
goto end;
|
335 |
}
|
336 |
*(int *)(linkPtr->addr) = linkPtr->lastValue.i;
|
337 |
break;
|
338 |
case TCL_LINK_DOUBLE:
|
339 |
if (Tcl_GetDouble(interp, value, &linkPtr->lastValue.d)
|
340 |
!= TCL_OK) {
|
341 |
Tcl_SetObjResult(interp, objPtr);
|
342 |
Tcl_SetVar(interp, linkPtr->varName,
|
343 |
StringValue(linkPtr, buffer), TCL_GLOBAL_ONLY);
|
344 |
result = "variable must have real value";
|
345 |
goto end;
|
346 |
}
|
347 |
*(double *)(linkPtr->addr) = linkPtr->lastValue.d;
|
348 |
break;
|
349 |
case TCL_LINK_BOOLEAN:
|
350 |
if (Tcl_GetBoolean(interp, value, &linkPtr->lastValue.i)
|
351 |
!= TCL_OK) {
|
352 |
Tcl_SetObjResult(interp, objPtr);
|
353 |
Tcl_SetVar(interp, linkPtr->varName,
|
354 |
StringValue(linkPtr, buffer), TCL_GLOBAL_ONLY);
|
355 |
result = "variable must have boolean value";
|
356 |
goto end;
|
357 |
}
|
358 |
*(int *)(linkPtr->addr) = linkPtr->lastValue.i;
|
359 |
break;
|
360 |
case TCL_LINK_STRING:
|
361 |
pp = (char **)(linkPtr->addr);
|
362 |
if (*pp != NULL) {
|
363 |
ckfree(*pp);
|
364 |
}
|
365 |
*pp = (char *) ckalloc((unsigned) (strlen(value) + 1));
|
366 |
strcpy(*pp, value);
|
367 |
break;
|
368 |
default:
|
369 |
return "internal error: bad linked variable type";
|
370 |
}
|
371 |
end:
|
372 |
Tcl_DecrRefCount(objPtr);
|
373 |
return result;
|
374 |
}
|
375 |
|
376 |
/*
|
377 |
*----------------------------------------------------------------------
|
378 |
*
|
379 |
* StringValue --
|
380 |
*
|
381 |
* Converts the value of a C variable to a string for use in a
|
382 |
* Tcl variable to which it is linked.
|
383 |
*
|
384 |
* Results:
|
385 |
* The return value is a pointer to a string that represents
|
386 |
* the value of the C variable given by linkPtr.
|
387 |
*
|
388 |
* Side effects:
|
389 |
* None.
|
390 |
*
|
391 |
*----------------------------------------------------------------------
|
392 |
*/
|
393 |
|
394 |
static char *
|
395 |
StringValue(linkPtr, buffer)
|
396 |
Link *linkPtr; /* Structure describing linked variable. */
|
397 |
char *buffer; /* Small buffer to use for converting
|
398 |
* values. Must have TCL_DOUBLE_SPACE
|
399 |
* bytes or more. */
|
400 |
{
|
401 |
char *p;
|
402 |
|
403 |
switch (linkPtr->type) {
|
404 |
case TCL_LINK_INT:
|
405 |
linkPtr->lastValue.i = *(int *)(linkPtr->addr);
|
406 |
TclFormatInt(buffer, linkPtr->lastValue.i);
|
407 |
return buffer;
|
408 |
case TCL_LINK_DOUBLE:
|
409 |
linkPtr->lastValue.d = *(double *)(linkPtr->addr);
|
410 |
Tcl_PrintDouble((Tcl_Interp *) NULL, linkPtr->lastValue.d, buffer);
|
411 |
return buffer;
|
412 |
case TCL_LINK_BOOLEAN:
|
413 |
linkPtr->lastValue.i = *(int *)(linkPtr->addr);
|
414 |
if (linkPtr->lastValue.i != 0) {
|
415 |
return "1";
|
416 |
}
|
417 |
return "0";
|
418 |
case TCL_LINK_STRING:
|
419 |
p = *(char **)(linkPtr->addr);
|
420 |
if (p == NULL) {
|
421 |
return "NULL";
|
422 |
}
|
423 |
return p;
|
424 |
}
|
425 |
|
426 |
/*
|
427 |
* This code only gets executed if the link type is unknown
|
428 |
* (shouldn't ever happen).
|
429 |
*/
|
430 |
|
431 |
return "??";
|
432 |
}
|
433 |
|
434 |
|
435 |
/* $History: tcllink.c $
|
436 |
*
|
437 |
* ***************** Version 1 *****************
|
438 |
* User: Dtashley Date: 1/02/01 Time: 1:33a
|
439 |
* Created in $/IjuScripter, IjuConsole/Source/Tcl Base
|
440 |
* Initial check-in.
|
441 |
*/
|
442 |
|
443 |
/* End of TCLLINK.C */ |