1 | /* |
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2 | * tclResolve.c -- |
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3 | * |
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4 | * Contains hooks for customized command/variable name resolution |
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5 | * schemes. These hooks allow extensions like [incr Tcl] to add their own |
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6 | * name resolution rules to the Tcl language. Rules can be applied to a |
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7 | * particular namespace, to the interpreter as a whole, or both. |
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8 | * |
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9 | * Copyright (c) 1998 Lucent Technologies, Inc. |
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10 | * |
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11 | * See the file "license.terms" for information on usage and redistribution of |
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12 | * this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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13 | * |
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14 | * RCS: @(#) $Id: tclResolve.c,v 1.9 2007/04/05 13:20:49 dkf Exp $ |
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15 | */ |
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16 | |
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17 | #include "tclInt.h" |
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18 | |
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19 | /* |
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20 | * Declarations for functions local to this file: |
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21 | */ |
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22 | |
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23 | static void BumpCmdRefEpochs(Namespace *nsPtr); |
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24 | |
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25 | /* |
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26 | *---------------------------------------------------------------------- |
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27 | * |
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28 | * Tcl_AddInterpResolvers -- |
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29 | * |
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30 | * Adds a set of command/variable resolution functions to an interpreter. |
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31 | * These functions are consulted when commands are resolved in |
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32 | * Tcl_FindCommand, and when variables are resolved in TclLookupVar and |
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33 | * LookupCompiledLocal. Each namespace may also have its own set of |
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34 | * resolution functions which take precedence over those for the |
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35 | * interpreter. |
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36 | * |
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37 | * When a name is resolved, it is handled as follows. First, the name is |
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38 | * passed to the resolution functions for the namespace. If not resolved, |
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39 | * the name is passed to each of the resolution functions added to the |
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40 | * interpreter. Finally, if still not resolved, the name is handled using |
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41 | * the default Tcl rules for name resolution. |
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42 | * |
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43 | * Results: |
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44 | * Returns pointers to the current name resolution functions in the |
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45 | * cmdProcPtr, varProcPtr and compiledVarProcPtr arguments. |
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46 | * |
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47 | * Side effects: |
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48 | * If a compiledVarProc is specified, this function bumps the |
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49 | * compileEpoch for the interpreter, forcing all code to be recompiled. |
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50 | * If a cmdProc is specified, this function bumps the cmdRefEpoch in all |
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51 | * namespaces, forcing commands to be resolved again using the new rules. |
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52 | * |
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53 | *---------------------------------------------------------------------- |
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54 | */ |
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55 | |
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56 | void |
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57 | Tcl_AddInterpResolvers( |
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58 | Tcl_Interp *interp, /* Interpreter whose name resolution rules are |
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59 | * being modified. */ |
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60 | CONST char *name, /* Name of this resolution scheme. */ |
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61 | Tcl_ResolveCmdProc *cmdProc,/* New function for command resolution. */ |
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62 | Tcl_ResolveVarProc *varProc,/* Function for variable resolution at |
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63 | * runtime. */ |
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64 | Tcl_ResolveCompiledVarProc *compiledVarProc) |
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65 | /* Function for variable resolution at compile |
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66 | * time. */ |
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67 | { |
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68 | Interp *iPtr = (Interp *) interp; |
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69 | ResolverScheme *resPtr; |
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70 | |
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71 | /* |
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72 | * Since we're adding a new name resolution scheme, we must force all code |
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73 | * to be recompiled to use the new scheme. If there are new compiled |
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74 | * variable resolution rules, bump the compiler epoch to invalidate |
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75 | * compiled code. If there are new command resolution rules, bump the |
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76 | * cmdRefEpoch in all namespaces. |
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77 | */ |
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78 | |
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79 | if (compiledVarProc) { |
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80 | iPtr->compileEpoch++; |
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81 | } |
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82 | if (cmdProc) { |
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83 | BumpCmdRefEpochs(iPtr->globalNsPtr); |
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84 | } |
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85 | |
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86 | /* |
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87 | * Look for an existing scheme with the given name. If found, then replace |
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88 | * its rules. |
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89 | */ |
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90 | |
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91 | for (resPtr=iPtr->resolverPtr ; resPtr!=NULL ; resPtr=resPtr->nextPtr) { |
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92 | if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) { |
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93 | resPtr->cmdResProc = cmdProc; |
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94 | resPtr->varResProc = varProc; |
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95 | resPtr->compiledVarResProc = compiledVarProc; |
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96 | return; |
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97 | } |
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98 | } |
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99 | |
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100 | /* |
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101 | * Otherwise, this is a new scheme. Add it to the FRONT of the linked |
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102 | * list, so that it overrides existing schemes. |
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103 | */ |
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104 | |
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105 | resPtr = (ResolverScheme *) ckalloc(sizeof(ResolverScheme)); |
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106 | resPtr->name = (char *) ckalloc((unsigned)(strlen(name) + 1)); |
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107 | strcpy(resPtr->name, name); |
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108 | resPtr->cmdResProc = cmdProc; |
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109 | resPtr->varResProc = varProc; |
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110 | resPtr->compiledVarResProc = compiledVarProc; |
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111 | resPtr->nextPtr = iPtr->resolverPtr; |
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112 | iPtr->resolverPtr = resPtr; |
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113 | } |
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114 | |
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115 | /* |
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116 | *---------------------------------------------------------------------- |
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117 | * |
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118 | * Tcl_GetInterpResolvers -- |
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119 | * |
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120 | * Looks for a set of command/variable resolution functions with the |
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121 | * given name in an interpreter. These functions are registered by |
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122 | * calling Tcl_AddInterpResolvers. |
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123 | * |
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124 | * Results: |
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125 | * If the name is recognized, this function returns non-zero, along with |
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126 | * pointers to the name resolution functions in the Tcl_ResolverInfo |
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127 | * structure. If the name is not recognized, this function returns zero. |
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128 | * |
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129 | * Side effects: |
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130 | * None. |
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131 | * |
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132 | *---------------------------------------------------------------------- |
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133 | */ |
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134 | |
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135 | int |
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136 | Tcl_GetInterpResolvers( |
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137 | Tcl_Interp *interp, /* Interpreter whose name resolution rules are |
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138 | * being queried. */ |
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139 | CONST char *name, /* Look for a scheme with this name. */ |
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140 | Tcl_ResolverInfo *resInfoPtr) |
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141 | /* Returns pointers to the functions, if |
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142 | * found */ |
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143 | { |
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144 | Interp *iPtr = (Interp *) interp; |
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145 | ResolverScheme *resPtr; |
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146 | |
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147 | /* |
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148 | * Look for an existing scheme with the given name. If found, then return |
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149 | * pointers to its functions. |
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150 | */ |
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151 | |
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152 | for (resPtr=iPtr->resolverPtr ; resPtr!=NULL ; resPtr=resPtr->nextPtr) { |
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153 | if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) { |
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154 | resInfoPtr->cmdResProc = resPtr->cmdResProc; |
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155 | resInfoPtr->varResProc = resPtr->varResProc; |
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156 | resInfoPtr->compiledVarResProc = resPtr->compiledVarResProc; |
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157 | return 1; |
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158 | } |
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159 | } |
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160 | |
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161 | return 0; |
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162 | } |
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163 | |
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164 | /* |
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165 | *---------------------------------------------------------------------- |
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166 | * |
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167 | * Tcl_RemoveInterpResolvers -- |
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168 | * |
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169 | * Removes a set of command/variable resolution functions previously |
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170 | * added by Tcl_AddInterpResolvers. The next time a command/variable name |
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171 | * is resolved, these functions won't be consulted. |
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172 | * |
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173 | * Results: |
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174 | * Returns non-zero if the name was recognized and the resolution scheme |
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175 | * was deleted. Returns zero otherwise. |
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176 | * |
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177 | * Side effects: |
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178 | * If a scheme with a compiledVarProc was deleted, this function bumps |
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179 | * the compileEpoch for the interpreter, forcing all code to be |
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180 | * recompiled. If a scheme with a cmdProc was deleted, this function |
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181 | * bumps the cmdRefEpoch in all namespaces, forcing commands to be |
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182 | * resolved again using the new rules. |
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183 | * |
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184 | *---------------------------------------------------------------------- |
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185 | */ |
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186 | |
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187 | int |
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188 | Tcl_RemoveInterpResolvers( |
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189 | Tcl_Interp *interp, /* Interpreter whose name resolution rules are |
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190 | * being modified. */ |
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191 | CONST char *name) /* Name of the scheme to be removed. */ |
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192 | { |
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193 | Interp *iPtr = (Interp *) interp; |
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194 | ResolverScheme **prevPtrPtr, *resPtr; |
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195 | |
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196 | /* |
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197 | * Look for an existing scheme with the given name. |
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198 | */ |
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199 | |
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200 | prevPtrPtr = &iPtr->resolverPtr; |
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201 | for (resPtr=iPtr->resolverPtr ; resPtr!=NULL ; resPtr=resPtr->nextPtr) { |
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202 | if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) { |
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203 | break; |
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204 | } |
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205 | prevPtrPtr = &resPtr->nextPtr; |
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206 | } |
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207 | |
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208 | /* |
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209 | * If we found the scheme, delete it. |
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210 | */ |
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211 | |
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212 | if (resPtr) { |
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213 | /* |
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214 | * If we're deleting a scheme with compiled variable resolution rules, |
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215 | * bump the compiler epoch to invalidate compiled code. If we're |
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216 | * deleting a scheme with command resolution rules, bump the |
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217 | * cmdRefEpoch in all namespaces. |
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218 | */ |
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219 | |
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220 | if (resPtr->compiledVarResProc) { |
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221 | iPtr->compileEpoch++; |
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222 | } |
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223 | if (resPtr->cmdResProc) { |
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224 | BumpCmdRefEpochs(iPtr->globalNsPtr); |
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225 | } |
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226 | |
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227 | *prevPtrPtr = resPtr->nextPtr; |
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228 | ckfree(resPtr->name); |
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229 | ckfree((char *) resPtr); |
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230 | |
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231 | return 1; |
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232 | } |
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233 | return 0; |
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234 | } |
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235 | |
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236 | /* |
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237 | *---------------------------------------------------------------------- |
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238 | * |
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239 | * BumpCmdRefEpochs -- |
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240 | * |
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241 | * This function is used to bump the cmdRefEpoch counters in the |
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242 | * specified namespace and all of its child namespaces. It is used |
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243 | * whenever name resolution schemes are added/removed from an |
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244 | * interpreter, to invalidate all command references. |
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245 | * |
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246 | * Results: |
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247 | * None. |
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248 | * |
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249 | * Side effects: |
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250 | * Bumps the cmdRefEpoch in the specified namespace and its children, |
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251 | * recursively. |
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252 | * |
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253 | *---------------------------------------------------------------------- |
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254 | */ |
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255 | |
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256 | static void |
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257 | BumpCmdRefEpochs( |
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258 | Namespace *nsPtr) /* Namespace being modified. */ |
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259 | { |
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260 | Tcl_HashEntry *entry; |
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261 | Tcl_HashSearch search; |
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262 | |
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263 | nsPtr->cmdRefEpoch++; |
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264 | |
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265 | for (entry = Tcl_FirstHashEntry(&nsPtr->childTable, &search); |
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266 | entry != NULL; entry = Tcl_NextHashEntry(&search)) { |
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267 | Namespace *childNsPtr = (Namespace *) Tcl_GetHashValue(entry); |
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268 | BumpCmdRefEpochs(childNsPtr); |
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269 | } |
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270 | TclInvalidateNsPath(nsPtr); |
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271 | } |
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272 | |
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273 | /* |
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274 | *---------------------------------------------------------------------- |
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275 | * |
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276 | * Tcl_SetNamespaceResolvers -- |
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277 | * |
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278 | * Sets the command/variable resolution functions for a namespace, |
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279 | * thereby changing the way that command/variable names are interpreted. |
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280 | * This allows extension writers to support different name resolution |
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281 | * schemes, such as those for object-oriented packages. |
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282 | * |
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283 | * Command resolution is handled by a function of the following type: |
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284 | * |
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285 | * typedef int (*Tcl_ResolveCmdProc)(Tcl_Interp *interp, |
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286 | * CONST char *name, Tcl_Namespace *context, |
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287 | * int flags, Tcl_Command *rPtr); |
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288 | * |
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289 | * Whenever a command is executed or Tcl_FindCommand is invoked within |
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290 | * the namespace, this function is called to resolve the command name. If |
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291 | * this function is able to resolve the name, it should return the status |
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292 | * code TCL_OK, along with the corresponding Tcl_Command in the rPtr |
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293 | * argument. Otherwise, the function can return TCL_CONTINUE, and the |
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294 | * command will be treated under the usual name resolution rules. Or, it |
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295 | * can return TCL_ERROR, and the command will be considered invalid. |
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296 | * |
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297 | * Variable resolution is handled by two functions. The first is called |
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298 | * whenever a variable needs to be resolved at compile time: |
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299 | * |
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300 | * typedef int (*Tcl_ResolveCompiledVarProc)(Tcl_Interp *interp, |
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301 | * CONST char *name, Tcl_Namespace *context, |
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302 | * Tcl_ResolvedVarInfo *rPtr); |
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303 | * |
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304 | * If this function is able to resolve the name, it should return the |
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305 | * status code TCL_OK, along with variable resolution info in the rPtr |
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306 | * argument; this info will be used to set up compiled locals in the call |
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307 | * frame at runtime. The function may also return TCL_CONTINUE, and the |
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308 | * variable will be treated under the usual name resolution rules. Or, it |
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309 | * can return TCL_ERROR, and the variable will be considered invalid. |
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310 | * |
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311 | * Another function is used whenever a variable needs to be resolved at |
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312 | * runtime but it is not recognized as a compiled local. (For example, |
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313 | * the variable may be requested via Tcl_FindNamespaceVar.) This function |
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314 | * has the following type: |
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315 | * |
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316 | * typedef int (*Tcl_ResolveVarProc)(Tcl_Interp *interp, |
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317 | * CONST char *name, Tcl_Namespace *context, |
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318 | * int flags, Tcl_Var *rPtr); |
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319 | * |
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320 | * This function is quite similar to the compile-time version. It returns |
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321 | * the same status codes, but if variable resolution succeeds, this |
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322 | * function returns a Tcl_Var directly via the rPtr argument. |
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323 | * |
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324 | * Results: |
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325 | * Nothing. |
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326 | * |
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327 | * Side effects: |
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328 | * Bumps the command epoch counter for the namespace, invalidating all |
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329 | * command references in that namespace. Also bumps the resolver epoch |
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330 | * counter for the namespace, forcing all code in the namespace to be |
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331 | * recompiled. |
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332 | * |
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333 | *---------------------------------------------------------------------- |
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334 | */ |
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335 | |
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336 | void |
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337 | Tcl_SetNamespaceResolvers( |
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338 | Tcl_Namespace *namespacePtr,/* Namespace whose resolution rules are being |
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339 | * modified. */ |
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340 | Tcl_ResolveCmdProc *cmdProc,/* Function for command resolution */ |
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341 | Tcl_ResolveVarProc *varProc,/* Function for variable resolution at |
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342 | * run-time */ |
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343 | Tcl_ResolveCompiledVarProc *compiledVarProc) |
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344 | /* Function for variable resolution at compile |
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345 | * time. */ |
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346 | { |
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347 | Namespace *nsPtr = (Namespace *) namespacePtr; |
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348 | |
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349 | /* |
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350 | * Plug in the new command resolver, and bump the epoch counters so that |
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351 | * all code will have to be recompiled and all commands will have to be |
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352 | * resolved again using the new policy. |
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353 | */ |
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354 | |
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355 | nsPtr->cmdResProc = cmdProc; |
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356 | nsPtr->varResProc = varProc; |
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357 | nsPtr->compiledVarResProc = compiledVarProc; |
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358 | |
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359 | nsPtr->cmdRefEpoch++; |
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360 | nsPtr->resolverEpoch++; |
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361 | TclInvalidateNsPath(nsPtr); |
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362 | } |
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363 | |
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364 | /* |
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365 | *---------------------------------------------------------------------- |
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366 | * |
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367 | * Tcl_GetNamespaceResolvers -- |
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368 | * |
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369 | * Returns the current command/variable resolution functions for a |
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370 | * namespace. By default, these functions are NULL. New functions can be |
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371 | * installed by calling Tcl_SetNamespaceResolvers, to provide new name |
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372 | * resolution rules. |
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373 | * |
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374 | * Results: |
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375 | * Returns non-zero if any name resolution functions have been assigned |
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376 | * to this namespace; also returns pointers to the functions in the |
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377 | * Tcl_ResolverInfo structure. Returns zero otherwise. |
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378 | * |
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379 | * Side effects: |
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380 | * None. |
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381 | * |
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382 | *---------------------------------------------------------------------- |
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383 | */ |
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384 | |
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385 | int |
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386 | Tcl_GetNamespaceResolvers( |
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387 | Tcl_Namespace *namespacePtr,/* Namespace whose resolution rules are being |
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388 | * modified. */ |
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389 | Tcl_ResolverInfo *resInfoPtr) |
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390 | /* Returns: pointers for all name resolution |
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391 | * functions assigned to this namespace. */ |
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392 | { |
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393 | Namespace *nsPtr = (Namespace *) namespacePtr; |
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394 | |
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395 | resInfoPtr->cmdResProc = nsPtr->cmdResProc; |
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396 | resInfoPtr->varResProc = nsPtr->varResProc; |
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397 | resInfoPtr->compiledVarResProc = nsPtr->compiledVarResProc; |
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398 | |
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399 | if (nsPtr->cmdResProc != NULL || nsPtr->varResProc != NULL || |
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400 | nsPtr->compiledVarResProc != NULL) { |
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401 | return 1; |
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402 | } |
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403 | return 0; |
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404 | } |
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405 | |
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406 | /* |
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407 | * Local Variables: |
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408 | * mode: c |
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409 | * c-basic-offset: 4 |
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410 | * fill-column: 78 |
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411 | * End: |
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412 | */ |
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