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