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 |
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6 | * their own name resolution rules to the Tcl language. Rules can |
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7 | * be applied to a particular namespace, to the interpreter as a |
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8 | * whole, or both. |
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9 | * |
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10 | * Copyright (c) 1998 Lucent Technologies, Inc. |
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11 | * |
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12 | * See the file "license.terms" for information on usage and redistribution |
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13 | * of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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14 | * |
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15 | * RCS: @(#) $Id: tclResolve.c,v 1.1 2008-06-04 13:58:10 demin Exp $ |
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16 | */ |
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17 | |
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18 | #include "tclInt.h" |
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19 | |
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20 | /* |
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21 | * Declarations for procedures local to this file: |
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22 | */ |
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23 | |
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24 | static void BumpCmdRefEpochs _ANSI_ARGS_((Namespace *nsPtr)); |
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25 | |
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26 | |
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27 | /* |
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28 | *---------------------------------------------------------------------- |
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29 | * |
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30 | * Tcl_AddInterpResolvers -- |
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31 | * |
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32 | * Adds a set of command/variable resolution procedures to an |
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33 | * interpreter. These procedures are consulted when commands |
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34 | * are resolved in Tcl_FindCommand, and when variables are |
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35 | * resolved in TclLookupVar and LookupCompiledLocal. Each |
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36 | * namespace may also have its own set of resolution procedures |
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37 | * which take precedence over those for the interpreter. |
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38 | * |
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39 | * When a name is resolved, it is handled as follows. First, |
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40 | * the name is passed to the resolution procedures for the |
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41 | * namespace. If not resolved, the name is passed to each of |
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42 | * the resolution procedures added to the interpreter. Finally, |
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43 | * if still not resolved, the name is handled using the default |
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44 | * Tcl rules for name resolution. |
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45 | * |
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46 | * Results: |
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47 | * Returns pointers to the current name resolution procedures |
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48 | * in the cmdProcPtr, varProcPtr and compiledVarProcPtr |
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49 | * arguments. |
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50 | * |
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51 | * Side effects: |
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52 | * If a compiledVarProc is specified, this procedure bumps the |
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53 | * compileEpoch for the interpreter, forcing all code to be |
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54 | * recompiled. If a cmdProc is specified, this procedure bumps |
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55 | * the cmdRefEpoch in all namespaces, forcing commands to be |
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56 | * resolved again using the new rules. |
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57 | * |
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58 | *---------------------------------------------------------------------- |
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59 | */ |
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60 | |
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61 | void |
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62 | Tcl_AddInterpResolvers(interp, name, cmdProc, varProc, compiledVarProc) |
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63 | |
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64 | Tcl_Interp *interp; /* Interpreter whose name resolution |
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65 | * rules are being modified. */ |
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66 | char *name; /* Name of this resolution scheme. */ |
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67 | Tcl_ResolveCmdProc *cmdProc; /* New procedure for command |
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68 | * resolution */ |
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69 | Tcl_ResolveVarProc *varProc; /* Procedure for variable resolution |
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70 | * at runtime */ |
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71 | Tcl_ResolveCompiledVarProc *compiledVarProc; |
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72 | /* Procedure for variable resolution |
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73 | * at compile time. */ |
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74 | { |
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75 | Interp *iPtr = (Interp*)interp; |
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76 | ResolverScheme *resPtr; |
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77 | |
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78 | /* |
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79 | * Since we're adding a new name resolution scheme, we must force |
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80 | * all code to be recompiled to use the new scheme. If there |
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81 | * are new compiled variable resolution rules, bump the compiler |
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82 | * epoch to invalidate compiled code. If there are new command |
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83 | * resolution rules, bump the cmdRefEpoch in all namespaces. |
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84 | */ |
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85 | if (compiledVarProc) { |
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86 | iPtr->compileEpoch++; |
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87 | } |
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88 | if (cmdProc) { |
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89 | BumpCmdRefEpochs(iPtr->globalNsPtr); |
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90 | } |
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91 | |
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92 | /* |
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93 | * Look for an existing scheme with the given name. If found, |
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94 | * then replace its rules. |
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95 | */ |
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96 | for (resPtr = iPtr->resolverPtr; resPtr != NULL; resPtr = resPtr->nextPtr) { |
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97 | if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) { |
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98 | resPtr->cmdResProc = cmdProc; |
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99 | resPtr->varResProc = varProc; |
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100 | resPtr->compiledVarResProc = compiledVarProc; |
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101 | return; |
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102 | } |
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103 | } |
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104 | |
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105 | /* |
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106 | * Otherwise, this is a new scheme. Add it to the FRONT |
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107 | * of the linked list, so that it overrides existing schemes. |
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108 | */ |
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109 | resPtr = (ResolverScheme *) ckalloc(sizeof(ResolverScheme)); |
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110 | resPtr->name = (char*)ckalloc((unsigned)(strlen(name)+1)); |
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111 | strcpy(resPtr->name, name); |
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112 | resPtr->cmdResProc = cmdProc; |
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113 | resPtr->varResProc = varProc; |
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114 | resPtr->compiledVarResProc = compiledVarProc; |
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115 | resPtr->nextPtr = iPtr->resolverPtr; |
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116 | iPtr->resolverPtr = resPtr; |
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117 | } |
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118 | |
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119 | /* |
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120 | *---------------------------------------------------------------------- |
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121 | * |
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122 | * Tcl_GetInterpResolvers -- |
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123 | * |
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124 | * Looks for a set of command/variable resolution procedures with |
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125 | * the given name in an interpreter. These procedures are |
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126 | * registered by calling Tcl_AddInterpResolvers. |
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127 | * |
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128 | * Results: |
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129 | * If the name is recognized, this procedure returns non-zero, |
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130 | * along with pointers to the name resolution procedures in |
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131 | * the Tcl_ResolverInfo structure. If the name is not recognized, |
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132 | * this procedure returns zero. |
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133 | * |
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134 | * Side effects: |
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135 | * None. |
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136 | * |
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137 | *---------------------------------------------------------------------- |
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138 | */ |
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139 | |
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140 | int |
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141 | Tcl_GetInterpResolvers(interp, name, resInfoPtr) |
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142 | |
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143 | Tcl_Interp *interp; /* Interpreter whose name resolution |
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144 | * rules are being queried. */ |
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145 | char *name; /* Look for a scheme with this name. */ |
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146 | Tcl_ResolverInfo *resInfoPtr; /* Returns pointers to the procedures, |
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147 | * if found */ |
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148 | { |
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149 | Interp *iPtr = (Interp*)interp; |
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150 | ResolverScheme *resPtr; |
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151 | |
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152 | /* |
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153 | * Look for an existing scheme with the given name. If found, |
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154 | * then return pointers to its procedures. |
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155 | */ |
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156 | for (resPtr = iPtr->resolverPtr; resPtr != NULL; resPtr = resPtr->nextPtr) { |
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157 | if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) { |
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158 | resInfoPtr->cmdResProc = resPtr->cmdResProc; |
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159 | resInfoPtr->varResProc = resPtr->varResProc; |
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160 | resInfoPtr->compiledVarResProc = resPtr->compiledVarResProc; |
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161 | return 1; |
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162 | } |
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163 | } |
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164 | |
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165 | return 0; |
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166 | } |
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167 | |
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168 | /* |
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169 | *---------------------------------------------------------------------- |
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170 | * |
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171 | * Tcl_RemoveInterpResolvers -- |
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172 | * |
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173 | * Removes a set of command/variable resolution procedures |
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174 | * previously added by Tcl_AddInterpResolvers. The next time |
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175 | * a command/variable name is resolved, these procedures |
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176 | * won't be consulted. |
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177 | * |
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178 | * Results: |
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179 | * Returns non-zero if the name was recognized and the |
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180 | * resolution scheme was deleted. Returns zero otherwise. |
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181 | * |
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182 | * Side effects: |
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183 | * If a scheme with a compiledVarProc was deleted, this procedure |
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184 | * bumps the compileEpoch for the interpreter, forcing all code |
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185 | * to be recompiled. If a scheme with a cmdProc was deleted, |
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186 | * this procedure bumps the cmdRefEpoch in all namespaces, |
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187 | * forcing commands to be resolved again using the new rules. |
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188 | * |
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189 | *---------------------------------------------------------------------- |
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190 | */ |
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191 | |
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192 | int |
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193 | Tcl_RemoveInterpResolvers(interp, name) |
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194 | |
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195 | Tcl_Interp *interp; /* Interpreter whose name resolution |
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196 | * rules are being modified. */ |
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197 | char *name; /* Name of the scheme to be removed. */ |
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198 | { |
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199 | Interp *iPtr = (Interp*)interp; |
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200 | ResolverScheme **prevPtrPtr, *resPtr; |
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201 | |
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202 | /* |
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203 | * Look for an existing scheme with the given name. |
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204 | */ |
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205 | prevPtrPtr = &iPtr->resolverPtr; |
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206 | for (resPtr = iPtr->resolverPtr; resPtr != NULL; resPtr = resPtr->nextPtr) { |
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207 | if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) { |
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208 | break; |
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209 | } |
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210 | prevPtrPtr = &resPtr->nextPtr; |
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211 | } |
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212 | |
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213 | /* |
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214 | * If we found the scheme, delete it. |
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215 | */ |
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216 | if (resPtr) { |
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217 | /* |
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218 | * If we're deleting a scheme with compiled variable resolution |
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219 | * rules, bump the compiler epoch to invalidate compiled code. |
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220 | * If we're deleting a scheme with command resolution rules, |
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221 | * bump the cmdRefEpoch in all namespaces. |
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222 | */ |
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223 | if (resPtr->compiledVarResProc) { |
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224 | iPtr->compileEpoch++; |
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225 | } |
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226 | if (resPtr->cmdResProc) { |
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227 | BumpCmdRefEpochs(iPtr->globalNsPtr); |
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228 | } |
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229 | |
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230 | *prevPtrPtr = resPtr->nextPtr; |
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231 | ckfree(resPtr->name); |
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232 | ckfree((char *) resPtr); |
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233 | |
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234 | return 1; |
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235 | } |
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236 | return 0; |
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237 | } |
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238 | |
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239 | /* |
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240 | *---------------------------------------------------------------------- |
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241 | * |
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242 | * BumpCmdRefEpochs -- |
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243 | * |
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244 | * This procedure is used to bump the cmdRefEpoch counters in |
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245 | * the specified namespace and all of its child namespaces. |
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246 | * It is used whenever name resolution schemes are added/removed |
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247 | * from an interpreter, to invalidate all command references. |
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248 | * |
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249 | * Results: |
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250 | * None. |
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251 | * |
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252 | * Side effects: |
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253 | * Bumps the cmdRefEpoch in the specified namespace and its |
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254 | * children, recursively. |
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255 | * |
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256 | *---------------------------------------------------------------------- |
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257 | */ |
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258 | |
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259 | static void |
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260 | BumpCmdRefEpochs(nsPtr) |
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261 | Namespace *nsPtr; /* Namespace being modified. */ |
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262 | { |
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263 | Tcl_HashEntry *entry; |
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264 | Tcl_HashSearch search; |
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265 | Namespace *childNsPtr; |
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266 | |
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267 | nsPtr->cmdRefEpoch++; |
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268 | |
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269 | for (entry = Tcl_FirstHashEntry(&nsPtr->childTable, &search); |
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270 | entry != NULL; |
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271 | entry = Tcl_NextHashEntry(&search)) { |
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272 | |
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273 | childNsPtr = (Namespace *) Tcl_GetHashValue(entry); |
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274 | BumpCmdRefEpochs(childNsPtr); |
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275 | } |
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276 | } |
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277 | |
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278 | |
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279 | /* |
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280 | *---------------------------------------------------------------------- |
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281 | * |
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282 | * Tcl_SetNamespaceResolvers -- |
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283 | * |
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284 | * Sets the command/variable resolution procedures for a namespace, |
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285 | * thereby changing the way that command/variable names are |
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286 | * interpreted. This allows extension writers to support different |
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287 | * name resolution schemes, such as those for object-oriented |
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288 | * packages. |
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289 | * |
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290 | * Command resolution is handled by a procedure of the following |
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291 | * type: |
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292 | * |
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293 | * typedef int (Tcl_ResolveCmdProc) _ANSI_ARGS_(( |
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294 | * Tcl_Interp* interp, char* name, Tcl_Namespace *context, |
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295 | * int flags, Tcl_Command *rPtr)); |
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296 | * |
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297 | * Whenever a command is executed or Tcl_FindCommand is invoked |
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298 | * within the namespace, this procedure is called to resolve the |
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299 | * command name. If this procedure is able to resolve the name, |
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300 | * it should return the status code TCL_OK, along with the |
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301 | * corresponding Tcl_Command in the rPtr argument. Otherwise, |
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302 | * the procedure can return TCL_CONTINUE, and the command will |
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303 | * be treated under the usual name resolution rules. Or, it can |
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304 | * return TCL_ERROR, and the command will be considered invalid. |
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305 | * |
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306 | * Variable resolution is handled by two procedures. The first |
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307 | * is called whenever a variable needs to be resolved at compile |
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308 | * time: |
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309 | * |
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310 | * typedef int (Tcl_ResolveCompiledVarProc) _ANSI_ARGS_(( |
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311 | * Tcl_Interp* interp, char* name, Tcl_Namespace *context, |
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312 | * Tcl_ResolvedVarInfo *rPtr)); |
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313 | * |
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314 | * If this procedure is able to resolve the name, it should return |
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315 | * the status code TCL_OK, along with variable resolution info in |
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316 | * the rPtr argument; this info will be used to set up compiled |
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317 | * locals in the call frame at runtime. The procedure may also |
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318 | * return TCL_CONTINUE, and the variable will be treated under |
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319 | * the usual name resolution rules. Or, it can return TCL_ERROR, |
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320 | * and the variable will be considered invalid. |
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321 | * |
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322 | * Another procedure is used whenever a variable needs to be |
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323 | * resolved at runtime but it is not recognized as a compiled local. |
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324 | * (For example, the variable may be requested via |
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325 | * Tcl_FindNamespaceVar.) This procedure has the following type: |
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326 | * |
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327 | * typedef int (Tcl_ResolveVarProc) _ANSI_ARGS_(( |
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328 | * Tcl_Interp* interp, char* name, Tcl_Namespace *context, |
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329 | * int flags, Tcl_Var *rPtr)); |
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330 | * |
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331 | * This procedure is quite similar to the compile-time version. |
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332 | * It returns the same status codes, but if variable resolution |
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333 | * succeeds, this procedure returns a Tcl_Var directly via the |
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334 | * rPtr argument. |
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335 | * |
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336 | * Results: |
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337 | * Nothing. |
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338 | * |
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339 | * Side effects: |
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340 | * Bumps the command epoch counter for the namespace, invalidating |
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341 | * all command references in that namespace. Also bumps the |
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342 | * resolver epoch counter for the namespace, forcing all code |
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343 | * in the namespace to be recompiled. |
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344 | * |
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345 | *---------------------------------------------------------------------- |
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346 | */ |
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347 | |
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348 | void |
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349 | Tcl_SetNamespaceResolvers(namespacePtr, cmdProc, varProc, compiledVarProc) |
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350 | Tcl_Namespace *namespacePtr; /* Namespace whose resolution rules |
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351 | * are being modified. */ |
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352 | Tcl_ResolveCmdProc *cmdProc; /* Procedure for command resolution */ |
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353 | Tcl_ResolveVarProc *varProc; /* Procedure for variable resolution |
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354 | * at runtime */ |
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355 | Tcl_ResolveCompiledVarProc *compiledVarProc; |
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356 | /* Procedure for variable resolution |
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357 | * at compile time. */ |
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358 | { |
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359 | Namespace *nsPtr = (Namespace*)namespacePtr; |
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360 | |
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361 | /* |
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362 | * Plug in the new command resolver, and bump the epoch counters |
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363 | * so that all code will have to be recompiled and all commands |
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364 | * will have to be resolved again using the new policy. |
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365 | */ |
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366 | nsPtr->cmdResProc = cmdProc; |
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367 | nsPtr->varResProc = varProc; |
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368 | nsPtr->compiledVarResProc = compiledVarProc; |
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369 | |
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370 | nsPtr->cmdRefEpoch++; |
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371 | nsPtr->resolverEpoch++; |
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372 | } |
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373 | |
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374 | /* |
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375 | *---------------------------------------------------------------------- |
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376 | * |
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377 | * Tcl_GetNamespaceResolvers -- |
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378 | * |
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379 | * Returns the current command/variable resolution procedures |
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380 | * for a namespace. By default, these procedures are NULL. |
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381 | * New procedures can be installed by calling |
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382 | * Tcl_SetNamespaceResolvers, to provide new name resolution |
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383 | * rules. |
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384 | * |
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385 | * Results: |
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386 | * Returns non-zero if any name resolution procedures have been |
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387 | * assigned to this namespace; also returns pointers to the |
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388 | * procedures in the Tcl_ResolverInfo structure. Returns zero |
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389 | * otherwise. |
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390 | * |
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391 | * Side effects: |
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392 | * None. |
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393 | * |
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394 | *---------------------------------------------------------------------- |
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395 | */ |
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396 | |
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397 | int |
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398 | Tcl_GetNamespaceResolvers(namespacePtr, resInfoPtr) |
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399 | |
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400 | Tcl_Namespace *namespacePtr; /* Namespace whose resolution rules |
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401 | * are being modified. */ |
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402 | Tcl_ResolverInfo *resInfoPtr; /* Returns: pointers for all |
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403 | * name resolution procedures |
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404 | * assigned to this namespace. */ |
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405 | { |
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406 | Namespace *nsPtr = (Namespace*)namespacePtr; |
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407 | |
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408 | resInfoPtr->cmdResProc = nsPtr->cmdResProc; |
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409 | resInfoPtr->varResProc = nsPtr->varResProc; |
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410 | resInfoPtr->compiledVarResProc = nsPtr->compiledVarResProc; |
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411 | |
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412 | if (nsPtr->cmdResProc != NULL || |
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413 | nsPtr->varResProc != NULL || |
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414 | nsPtr->compiledVarResProc != NULL) { |
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415 | return 1; |
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416 | } |
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417 | return 0; |
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418 | } |
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