1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System;
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23 | using System.Reflection;
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24 | using System.Reflection.Emit;
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25 |
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26 | namespace HeuristicLab.Persistence {
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27 |
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28 | /// <summary>
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29 | /// Encapsulation and abstraction for access a data member of an object
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30 | /// regardless of it being a property or field. Additionally a
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31 | /// default value and an alternate name can be specified.
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32 | /// </summary>
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33 | public sealed class DataMemberAccessor {
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34 |
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35 | #region fields
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36 |
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37 | /// <summary>
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38 | /// The function to get the value of the data member.
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39 | /// </summary>
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40 | public readonly Func<object, object> Get;
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41 |
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42 | /// <summary>
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43 | /// The function to set the value of the data member.
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44 | /// </summary>
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45 | public readonly Action<object, object> Set;
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46 |
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47 | /// <summary>
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48 | /// The name of the data member.
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49 | /// </summary>
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50 | public readonly string Name;
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51 |
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52 | /// <summary>
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53 | /// The default value of the data member, can remain <c>null</c>
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54 | /// if no default value. If left null, this will also leave the
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55 | /// default value for value types (e.g. 0 for <c>int</c>).
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56 | /// </summary>
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57 | public readonly object DefaultValue;
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58 |
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59 | #endregion
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60 |
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61 | #region constructors
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62 |
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63 | /// <summary>
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64 | /// Create a <see cref="DataMemberAccessor"/> from a FieldInfo or
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65 | /// PropertyInfo for the give object.
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66 | /// </summary>
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67 | /// <param name="memberInfo">The member info.</param>
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68 | /// <param name="name">The name.</param>
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69 | /// <param name="defaultvalue">The defaultvalue.</param>
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70 | public DataMemberAccessor(MemberInfo memberInfo, string name, object defaultvalue) {
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71 | Get = GenerateGetter(memberInfo);
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72 | Set = GenerateSetter(memberInfo);
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73 | Name = name;
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74 | DefaultValue = defaultvalue;
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75 | }
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76 |
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77 | /// <summary>
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78 | /// Create an empty accessor that just encapsulates an object
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79 | /// without access.
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80 | /// </summary>
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81 | public DataMemberAccessor() {
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82 | Name = null;
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83 | DefaultValue = null;
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84 | Get = Id;
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85 | }
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86 |
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87 | /// <summary>
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88 | /// Create an empty accessor that just encapsulates an object
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89 | /// without access.
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90 | /// </summary>
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91 | /// <param name="name">The object's name.</param>
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92 | public DataMemberAccessor(string name) {
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93 | Name = name;
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94 | DefaultValue = null;
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95 | Get = Id;
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96 | }
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97 |
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98 | /// <summary>
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99 | /// Initializes a new instance of the <see cref="DataMemberAccessor"/> class using the
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100 | /// getter and setter from an exisiting instance but with a new name and default value.
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101 | /// </summary>
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102 | /// <param name="dma">The existing DataMemberAccessor.</param>
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103 | /// <param name="name">The new name.</param>
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104 | /// <param name="defaultValue">The new default value.</param>
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105 | public DataMemberAccessor(DataMemberAccessor dma, string name, object defaultValue) {
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106 | Get = dma.Get;
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107 | Set = dma.Set;
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108 | this.Name = name;
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109 | this.DefaultValue = defaultValue;
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110 | }
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111 |
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112 | #endregion
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113 |
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114 | #region auxiliary methods
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115 |
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116 | /// <summary>
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117 | /// Returns a <see cref="System.String"/> that represents this instance.
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118 | /// </summary>
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119 | /// <returns>
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120 | /// A <see cref="System.String"/> that represents this instance.
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121 | /// </returns>
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122 | public override string ToString() {
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123 | return String.Format("DataMemberAccessor({0}, {1}, {2}, {3})",
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124 | Name,
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125 | DefaultValue ?? "<null>",
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126 | Get.Method, Set.Method);
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127 | }
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128 |
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129 | /// <summary>
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130 | /// The identity function
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131 | /// </summary>
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132 | /// <param name="o">An object.</param>
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133 | /// <returns>its argument o unmodified.</returns>
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134 | public static object Id(object o) {
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135 | return o;
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136 | }
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137 |
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138 | #endregion
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139 |
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140 | #region static methods (code generators)
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141 |
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142 | /// <summary>
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143 | /// Generate a getter for the given field or property
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144 | /// </summary>
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145 | /// <param name="memberInfo">The member info.</param>
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146 | /// <returns></returns>
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147 | public static Func<object, object> GenerateGetter(MemberInfo memberInfo) {
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148 | if (memberInfo.MemberType == MemberTypes.Field) {
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149 | FieldInfo fieldInfo = (FieldInfo)memberInfo;
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150 | return GenerateFieldGetter(fieldInfo);
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151 | } else if (memberInfo.MemberType == MemberTypes.Property) {
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152 | return GeneratePropertyGetter((PropertyInfo)memberInfo);
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153 | } else {
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154 | throw new PersistenceException(
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155 | "The Storable attribute can only be applied to fields and properties.");
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156 | }
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157 | }
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158 |
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159 | /// <summary>
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160 | /// Generates a setter for the given field or property.
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161 | /// </summary>
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162 | /// <param name="memberInfo">The member info.</param>
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163 | /// <returns></returns>
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164 | public static Action<object, object> GenerateSetter(MemberInfo memberInfo) {
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165 | if (memberInfo.MemberType == MemberTypes.Field) {
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166 | FieldInfo fieldInfo = (FieldInfo)memberInfo;
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167 | return GenerateFieldSetter(fieldInfo);
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168 | } else if (memberInfo.MemberType == MemberTypes.Property) {
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169 | return GeneratePropertySetter((PropertyInfo)memberInfo);
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170 | } else {
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171 | throw new PersistenceException(
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172 | "The Storable attribute can only be applied to fields and properties.");
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173 | }
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174 | }
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175 |
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176 | /// <summary>
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177 | /// Generates a dynamically compiled getter to access fields (even private ones).
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178 | /// </summary>
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179 | /// <param name="fieldInfo">The field info.</param>
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180 | /// <returns>A Func<object, object></returns>
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181 | public static Func<object, object> GenerateFieldGetter(FieldInfo fieldInfo) {
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182 | DynamicMethod dm = new DynamicMethod("", typeof(object), new Type[] { typeof(object) }, fieldInfo.DeclaringType, true);
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183 | ILGenerator ilgen = dm.GetILGenerator();
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184 | ilgen.Emit(OpCodes.Ldarg_0);
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185 | ilgen.Emit(OpCodes.Castclass, fieldInfo.DeclaringType);
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186 | ilgen.Emit(OpCodes.Ldfld, fieldInfo);
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187 | ilgen.Emit(OpCodes.Box, fieldInfo.FieldType);
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188 | ilgen.Emit(OpCodes.Ret);
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189 | return (Func<object, object>)dm.CreateDelegate(typeof(Func<object, object>));
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190 | }
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191 |
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192 | /// <summary>
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193 | /// Generates a dynamically compiled setter to access fields (even private ones).
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194 | /// </summary>
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195 | /// <param name="fieldInfo">The field info.</param>
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196 | /// <returns>An Action<object, object%gt;</returns>
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197 | public static Action<object, object> GenerateFieldSetter(FieldInfo fieldInfo) {
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198 | DynamicMethod dm = new DynamicMethod("", null, new Type[] { typeof(object), typeof(object) }, fieldInfo.DeclaringType, true);
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199 | ILGenerator ilgen = dm.GetILGenerator();
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200 | ilgen.Emit(OpCodes.Ldarg_0);
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201 | ilgen.Emit(OpCodes.Castclass, fieldInfo.DeclaringType);
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202 | ilgen.Emit(OpCodes.Ldarg_1);
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203 | ilgen.Emit(OpCodes.Unbox_Any, fieldInfo.FieldType);
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204 | ilgen.Emit(OpCodes.Stfld, fieldInfo);
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205 | ilgen.Emit(OpCodes.Ret);
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206 | return (Action<object, object>)dm.CreateDelegate(typeof(Action<object, object>));
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207 | }
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208 |
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209 | /// <summary>
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210 | /// Generates a dynamically compiled getter to access properties (even private ones).
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211 | /// </summary>
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212 | /// <param name="propertyInfo">The property info.</param>
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213 | /// <returns>A Func<object, object></returns>
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214 | public static Func<object, object> GeneratePropertyGetter(PropertyInfo propertyInfo) {
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215 | MethodInfo getter = propertyInfo.GetGetMethod(true);
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216 | if (getter == null)
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217 | return null;
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218 | DynamicMethod dm = new DynamicMethod("", typeof(object), new Type[] { typeof(object) }, propertyInfo.DeclaringType, true);
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219 | ILGenerator ilgen = dm.GetILGenerator();
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220 | ilgen.Emit(OpCodes.Ldarg_0);
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221 | ilgen.Emit(OpCodes.Castclass, propertyInfo.DeclaringType);
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222 | ilgen.Emit(OpCodes.Callvirt, getter);
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223 | ilgen.Emit(OpCodes.Box, propertyInfo.PropertyType);
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224 | ilgen.Emit(OpCodes.Ret);
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225 | return (Func<object, object>)dm.CreateDelegate(typeof(Func<object, object>));
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226 | }
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227 |
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228 | /// <summary>
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229 | /// Generates a dynamically compiled setter to access properties (even private ones).
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230 | /// </summary>
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231 | /// <param name="propertyInfo">The property info.</param>
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232 | /// <returns>An Action<object, object%gt;</returns>
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233 | public static Action<object, object> GeneratePropertySetter(PropertyInfo propertyInfo) {
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234 | MethodInfo setter = propertyInfo.GetSetMethod(true);
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235 | if (setter == null)
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236 | return null;
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237 | DynamicMethod dm = new DynamicMethod("", null, new Type[] { typeof(object), typeof(object) }, propertyInfo.DeclaringType, true);
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238 | ILGenerator ilgen = dm.GetILGenerator();
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239 | ilgen.Emit(OpCodes.Ldarg_0);
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240 | ilgen.Emit(OpCodes.Castclass, propertyInfo.DeclaringType);
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241 | ilgen.Emit(OpCodes.Ldarg_1);
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242 | ilgen.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);
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243 | ilgen.Emit(OpCodes.Callvirt, setter);
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244 | ilgen.Emit(OpCodes.Ret);
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245 | return (Action<object, object>)dm.CreateDelegate(typeof(Action<object, object>));
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246 | }
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247 |
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248 | #endregion
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249 | }
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250 |
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251 | } |
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