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1 | office | 1 | /** |
2 | * @file NCDObject.h |
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3 | * @author Ambroz Bizjak <ambrop7@gmail.com> |
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4 | * |
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5 | * @section LICENSE |
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6 | * |
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7 | * Redistribution and use in source and binary forms, with or without |
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8 | * modification, are permitted provided that the following conditions are met: |
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9 | * 1. Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * 2. Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * 3. Neither the name of the author nor the |
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15 | * names of its contributors may be used to endorse or promote products |
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16 | * derived from this software without specific prior written permission. |
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17 | * |
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18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND |
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19 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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20 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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21 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
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22 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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23 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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24 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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25 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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27 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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28 | */ |
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29 | |||
30 | #ifndef BADVPN_NCDOBJECT_H |
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31 | #define BADVPN_NCDOBJECT_H |
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32 | |||
33 | #include <stddef.h> |
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34 | |||
35 | #include <misc/debug.h> |
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36 | #include <structure/LinkedList0.h> |
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37 | #include <ncd/NCDVal_types.h> |
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38 | #include <ncd/NCDStringIndex.h> |
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39 | #include <ncd/static_strings.h> |
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40 | |||
41 | /** |
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42 | * Represents an NCD object. |
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43 | * Objects expose the following functionalities: |
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44 | * - resolving variables by name, |
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45 | * - resolving objects by name, |
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46 | * - provide information for calling method-like statements. |
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47 | * |
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48 | * The NCDObject structure must not be stored persistently; it is only |
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49 | * valid at the time it was obtained, and any change of state in the |
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50 | * execution of the NCD program may render the object invalid. |
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51 | * However, the structure does not contain any resources, and can freely |
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52 | * be passed around by value. |
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53 | */ |
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54 | typedef struct NCDObject_s NCDObject; |
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55 | |||
56 | /** |
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57 | * Serves as an anchor point for NCDObjRef weak references. |
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58 | * A callback produces the temporary NCDObject values on demand. |
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59 | */ |
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60 | typedef struct NCDPersistentObj_s NCDPersistentObj; |
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61 | |||
62 | /** |
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63 | * A weak reference to an NCDPersistentObj. |
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64 | * This means that the existence of a reference does not prevent |
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65 | * the NCDPersistentObj from going away, rather when it goes away |
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66 | * the NCDObjRef becomes a broken reference - any further |
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67 | * dereference operations will fail "gracefully". |
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68 | */ |
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69 | typedef struct NCDObjRef_s NCDObjRef; |
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70 | |||
71 | /** |
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72 | * Callback function for variable resolution requests. |
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73 | * |
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74 | * @param obj const pointer to the NCDObject this is being called for. |
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75 | * {@link NCDObject_DataPtr} and {@link NCDObject_DataInt} can be |
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76 | * used to retrieve state information which was passed to |
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77 | * {@link NCDObject_Build} or {@link NCDObject_BuildFull}. |
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78 | * @param name name of the variable being resolved, in form of an {@link NCDStringIndex} |
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79 | * string identifier |
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80 | * @param mem pointer to the memory object where the resulting value should be |
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81 | * constructed |
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82 | * @param out_value If the variable exists, *out_value should be set to the value |
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83 | * reference to the result value. If the variable exists but there |
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84 | * was an error constructing the value, should be set to an |
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85 | * invalid value reference. Can be modified even if the variable |
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86 | * does not exist. |
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87 | * @return 1 if the variable exists, 0 if not |
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88 | */ |
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89 | typedef int (*NCDObject_func_getvar) (const NCDObject *obj, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out_value); |
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90 | |||
91 | /** |
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92 | * Callback function for object resolution requests. |
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93 | * |
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94 | * @param obj const pointer to the NCDObject this is being called for. |
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95 | * {@link NCDObject_DataPtr} and {@link NCDObject_DataInt} can be |
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96 | * used to retrieve state information which was passed to |
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97 | * {@link NCDObject_Build} or {@link NCDObject_BuildFull}. |
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98 | * @param name name of the object being resolved, in form of an {@link NCDStringIndex} |
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99 | * string identifier |
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100 | * @param out_object If the object exists, *out_object should be set to the result |
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101 | * object. Can be modified even if the object does not exist. |
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102 | * @return 1 if the object exists, 0 if not |
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103 | */ |
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104 | typedef int (*NCDObject_func_getobj) (const NCDObject *obj, NCD_string_id_t name, NCDObject *out_object); |
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105 | |||
106 | /** |
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107 | * A callback of NCDPersistentObj which produces the corresponding temporary |
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108 | * NCDObject value. |
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109 | */ |
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110 | typedef NCDObject (*NCDPersistentObj_func_retobj) (NCDPersistentObj const *pobj); |
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111 | |||
112 | struct NCDObject_s { |
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113 | NCD_string_id_t type; |
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114 | int data_int; |
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115 | void *data_ptr; |
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116 | void *method_user; |
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117 | NCDObject_func_getvar func_getvar; |
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118 | NCDObject_func_getobj func_getobj; |
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119 | NCDPersistentObj *pobj; |
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120 | }; |
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121 | |||
122 | struct NCDPersistentObj_s { |
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123 | NCDPersistentObj_func_retobj func_retobj; |
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124 | LinkedList0 refs_list; |
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125 | }; |
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126 | |||
127 | struct NCDObjRef_s { |
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128 | NCDPersistentObj *pobj; |
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129 | LinkedList0Node refs_list_node; |
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130 | }; |
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131 | |||
132 | /** |
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133 | * Basic object construction function. |
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134 | * This is equivalent to calling {@link NCDObject_BuildFull} with data_int=0, |
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135 | * method_user=data_ptr and pobj=NULL. See that function for detailed documentation. |
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136 | */ |
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137 | NCDObject NCDObject_Build (NCD_string_id_t type, void *data_ptr, NCDObject_func_getvar func_getvar, NCDObject_func_getobj func_getobj); |
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138 | |||
139 | /** |
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140 | * Constructs an {@link NCDObject} structure. |
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141 | * This is the full version where all supported parameters have to be provided. |
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142 | * In most cases, {@link NCDObject_Build} will suffice. |
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143 | * |
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144 | * @param type type of the object for the purpose of calling method-like statements |
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145 | * on the object, in form of an {@link NCDStringIndex} string identifier. |
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146 | * May be set to -1 if the object has no methods. |
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147 | * @param data_ptr state-keeping pointer which can be restored from callbacks using |
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148 | * {@link NCDObject_DataPtr} |
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149 | * @param data_int state-keeping integer which can be restored from callbacks using |
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150 | * {@link NCDObject_DataInt} |
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151 | * @param method_user state-keeping pointer to be passed to new method-like statements |
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152 | * created using this object. The value of this argument will be |
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153 | * available as params->method_user within the {@link NCDModule_func_new2} |
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154 | * module backend callback. |
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155 | * @param func_getvar callback for resolving variables within the object. This must not |
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156 | * be NULL; if the object exposes no variables, pass {@link NCDObject_no_getvar}. |
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157 | * @param func_getobj callback for resolving objects within the object. This must not |
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158 | * be NULL; if the object exposes no objects, pass {@link NCDObject_no_getobj}. |
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159 | * @param pobj pointer to an NCDPersistentObj, serving as a reference anchor for this |
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160 | * object. NULL if references are not supported by the object. |
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161 | * @return an NCDObject structure encapsulating the information given |
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162 | */ |
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163 | NCDObject NCDObject_BuildFull (NCD_string_id_t type, void *data_ptr, int data_int, void *method_user, NCDObject_func_getvar func_getvar, NCDObject_func_getobj func_getobj, NCDPersistentObj *pobj); |
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164 | |||
165 | /** |
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166 | * Returns the 'type' attribute; see {@link NCDObject_BuildFull}. |
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167 | */ |
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168 | NCD_string_id_t NCDObject_Type (const NCDObject *o); |
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169 | |||
170 | /** |
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171 | * Returns the 'data_ptr' attribute; see {@link NCDObject_BuildFull}. |
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172 | */ |
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173 | void * NCDObject_DataPtr (const NCDObject *o); |
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174 | |||
175 | /** |
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176 | * Returns the 'data_int' attribute; see {@link NCDObject_BuildFull}. |
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177 | */ |
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178 | int NCDObject_DataInt (const NCDObject *o); |
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179 | |||
180 | /** |
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181 | * Returns the 'method_user' attribute; see {@link NCDObject_BuildFull}. |
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182 | */ |
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183 | void * NCDObject_MethodUser (const NCDObject *o); |
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184 | |||
185 | /** |
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186 | * Attempts to resolve a variable within the object. |
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187 | * This just calls {@link NCDObject_func_getvar}, but also has some assertions to detect |
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188 | * incorrect behavior of the callback. |
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189 | */ |
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190 | int NCDObject_GetVar (const NCDObject *o, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out_value) WARN_UNUSED; |
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191 | |||
192 | /** |
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193 | * Attempts to resolve an object within the object. |
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194 | * This just calls {@link NCDObject_func_getobj}, but also has some assertions to detect |
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195 | * incorrect behavior of the callback. |
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196 | */ |
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197 | int NCDObject_GetObj (const NCDObject *o, NCD_string_id_t name, NCDObject *out_object) WARN_UNUSED; |
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198 | |||
199 | /** |
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200 | * Returns a pointer to the NCDPersistentObj pointer for this |
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201 | * object (if any). |
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202 | */ |
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203 | NCDPersistentObj * NCDObject_Pobj (const NCDObject *o); |
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204 | |||
205 | /** |
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206 | * Resolves a variable expression starting with this object. |
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207 | * A variable expression is usually represented in dotted form, |
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208 | * e.g. object1.object2.variable (for a named variable) or object1.object2.object3 |
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209 | * (for an empty string variable). This function however receives the expression |
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210 | * as an array of string identifiers. |
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211 | * |
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212 | * Consult the implementation for exact semantics of variable expression resolution. |
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213 | * |
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214 | * @param o object to start the resolution with |
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215 | * @param names pointer to an array of names for the resolution. May be NULL if num_names is 0. |
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216 | * @param num_names number in names in the array |
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217 | * @param mem pointer to the memory object where the resulting value |
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218 | * should be constructed |
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219 | * @param out_value If the variable exists, *out_value will be set to the value |
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220 | * reference to the result value. If the variable exists but there |
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221 | * was an error constructing the value, will be set to an |
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222 | * invalid value reference. May be modified even if the variable |
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223 | * does not exist. |
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224 | * @return 1 if the variable exists, 0 if not |
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225 | */ |
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226 | int NCDObject_ResolveVarExprCompact (const NCDObject *o, const NCD_string_id_t *names, size_t num_names, NCDValMem *mem, NCDValRef *out_value) WARN_UNUSED; |
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227 | |||
228 | /** |
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229 | * Resolves an object expression starting with this object. |
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230 | * An object expression is usually represented in dotted form, |
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231 | * e.g. object1.object2.object3. This function however receives the expression |
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232 | * as an array of string identifiers. |
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233 | * |
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234 | * Consult the implementation for exact semantics of object expression resolution. |
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235 | * |
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236 | * @param o object to start the resolution with |
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237 | * @param names pointer to an array of names for the resolution. May be NULL if num_names is 0. |
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238 | * @param num_names number in names in the array |
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239 | * @param out_object If the object exists, *out_object will be set to the result |
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240 | * object. May be modified even if the object does not exist. |
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241 | * @return 1 if the object exists, 0 if not |
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242 | */ |
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243 | int NCDObject_ResolveObjExprCompact (const NCDObject *o, const NCD_string_id_t *names, size_t num_names, NCDObject *out_object) WARN_UNUSED; |
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244 | |||
245 | /** |
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246 | * Returns 0. This can be used as a dummy variable resolution callback. |
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247 | */ |
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248 | int NCDObject_no_getvar (const NCDObject *obj, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out_value); |
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249 | |||
250 | /** |
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251 | * Returns 0. This can be used as a dummy object resolution callback. |
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252 | */ |
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253 | int NCDObject_no_getobj (const NCDObject *obj, NCD_string_id_t name, NCDObject *out_object); |
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254 | |||
255 | /** |
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256 | * Initializes an NCDPersistentObj, an anchor point for NCDObjRef |
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257 | * refrences. |
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258 | * |
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259 | * @param func_retobj callback for producing NCDObject temporary objects |
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260 | */ |
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261 | void NCDPersistentObj_Init (NCDPersistentObj *o, NCDPersistentObj_func_retobj func_retobj); |
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262 | |||
263 | /** |
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264 | * Frees the NCDPersistentObj. |
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265 | * This breaks any NCDObjRef references referencing this object. |
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266 | * This means that any further NCDObjRef_Deref calls on those |
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267 | * references will fail. |
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268 | */ |
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269 | void NCDPersistentObj_Free (NCDPersistentObj *o); |
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270 | |||
271 | /** |
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272 | * Initializes an object reference. |
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273 | * |
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274 | * @param pobj the NCDPersistentObj for the reference, or NULL to make |
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275 | * a broken reference |
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276 | */ |
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277 | void NCDObjRef_Init (NCDObjRef *o, NCDPersistentObj *pobj); |
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278 | |||
279 | /** |
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280 | * Frees the object reference. |
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281 | */ |
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282 | void NCDObjRef_Free (NCDObjRef *o); |
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283 | |||
284 | /** |
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285 | * Dereferences the object reference. |
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286 | * Note that the refernce will be broken if the originally |
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287 | * reference NCDPersistentObj was freed. |
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288 | * |
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289 | * @param res on success, *res will be set to the resulting NCDObject |
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290 | * @return 1 on success, 0 on failure (broken reference) |
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291 | */ |
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292 | int NCDObjRef_Deref (NCDObjRef *o, NCDObject *res) WARN_UNUSED; |
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293 | |||
294 | #endif |