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1 using System;
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2 using System.Collections.Generic;
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3 using System.Linq;
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4 using System.Linq.Expressions;
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5 using System.Reflection;
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6 using System.Reflection.Emit;
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7
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8 namespace BLToolkit.Emit
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9 {
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10 /// <summary>
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11 /// Creates and compiles types instances and methods using expressions, IL code generation
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12 /// </summary>
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13 /// <remarks>
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14 /// Inspired from:
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15 /// http://abhi.dcmembers.com/blog/2009/03/25/lambda-based-reflection-vs-normal-reflection-vs-direct-call-4/
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16 /// </remarks>
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17 public static class FunctionFactory
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18 {
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19 #region Delegates
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20
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21 public delegate object GenericGetter(object target);
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22
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23 public delegate void GenericSetter(object target, object value);
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24
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25 #endregion
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26
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27 #region Nested type: Il
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28
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29 public static class Il
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30 {
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31 public static object CreateInstance(Type type)
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32 {
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33 InstantiateObjectHandler instantiateObjectHandler =
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34 DynamicMethodCompiler.CreateInstantiateObjectHandler(type);
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35
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36 return instantiateObjectHandler();
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37 }
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38
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39 public static T CreateInstance<T>()
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40 {
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41 return (T) CreateInstance(typeof (T));
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42 }
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43
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44 public static SetHandler CreateSetHandler(Type type, string property)
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45 {
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46 PropertyInfo propertyInfo = type.GetProperty(property);
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47 return CreateSetHandler(type, propertyInfo);
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48 }
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49
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50 public static SetHandler CreateSetHandler(Type type, PropertyInfo propertyInfo)
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51 {
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52 SetHandler setHandler = DynamicMethodCompiler.CreateSetHandler(type, propertyInfo);
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53 return setHandler;
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54 }
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55
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56 public static SetHandler CreateSetHandler<T>(string property)
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57 {
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58 return CreateSetHandler(typeof (T), property);
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59 }
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60
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61 public static GetHandler CreateGetHandler(Type type, PropertyInfo propertyInfo)
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62 {
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63 GetHandler getHandler = DynamicMethodCompiler.CreateGetHandler(type, propertyInfo);
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64 return getHandler;
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65 }
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66
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67 public static GetHandler CreateGetHandler<T>(PropertyInfo propertyInfo)
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68 {
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69 return CreateGetHandler(typeof (T), propertyInfo);
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70 }
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71
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72 public static GetHandler CreateGetHandler<T>(string property)
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73 {
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74 PropertyInfo propertyInfo = typeof (T).GetProperty(property);
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75 return CreateGetHandler<T>(propertyInfo);
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76 }
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77
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78 ///
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79 /// Creates a dynamic setter for the property
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80 ///
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81 public static GenericSetter CreateSetMethod(PropertyInfo propertyInfo)
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82 {
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83 /*
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84 * If there's no setter return null
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85 */
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86 MethodInfo setMethod = propertyInfo.GetSetMethod();
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87 if (setMethod == null)
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88 return null;
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89
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90 /*
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91 * Create the dynamic method
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92 */
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93 var arguments = new Type[2];
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94 arguments[0] = arguments[1] = typeof (object);
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95
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96 var setter = new DynamicMethod(
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97 String.Concat("_Set", propertyInfo.Name, "_"),
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98 typeof (void), arguments, propertyInfo.DeclaringType);
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99 ILGenerator generator = setter.GetILGenerator();
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100 generator.Emit(OpCodes.Ldarg_0);
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101 generator.Emit(OpCodes.Castclass, propertyInfo.DeclaringType);
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102 generator.Emit(OpCodes.Ldarg_1);
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103
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104 if (propertyInfo.PropertyType.IsClass)
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105 generator.Emit(OpCodes.Castclass, propertyInfo.PropertyType);
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106 else
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107 generator.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);
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108
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109 generator.EmitCall(OpCodes.Callvirt, setMethod, null);
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110 generator.Emit(OpCodes.Ret);
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111
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112 /*
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113 * Create the delegate and return it
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114 */
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115 return (GenericSetter) setter.CreateDelegate(typeof (GenericSetter));
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116 }
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117
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118 ///
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119 /// Creates a dynamic getter for the property
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120 ///
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121 public static GenericGetter CreateGetMethod(PropertyInfo propertyInfo)
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122 {
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123 /*
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124 * If there's no getter return null
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125 */
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126 MethodInfo getMethod = propertyInfo.GetGetMethod();
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127 if (getMethod == null)
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128 return null;
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129
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130 /*
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131 * Create the dynamic method
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132 */
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133 var arguments = new Type[1];
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134 arguments[0] = typeof (object);
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135
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136 var getter = new DynamicMethod(
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137 String.Concat("_Get", propertyInfo.Name, "_"),
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138 typeof (object), arguments, propertyInfo.DeclaringType);
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139
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140 ILGenerator generator = getter.GetILGenerator();
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141 generator.DeclareLocal(typeof (object));
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142 generator.Emit(OpCodes.Ldarg_0);
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143 generator.Emit(OpCodes.Castclass, propertyInfo.DeclaringType);
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144 generator.EmitCall(OpCodes.Callvirt, getMethod, null);
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145
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146 if (!propertyInfo.PropertyType.IsClass)
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147 generator.Emit(OpCodes.Box, propertyInfo.PropertyType);
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148
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149 generator.Emit(OpCodes.Ret);
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150
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151 /*
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152 * Create the delegate and return it
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153 */
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154 return (GenericGetter) getter.CreateDelegate(typeof (GenericGetter));
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155 }
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156 }
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157
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158 #endregion
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159
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160 #region Nested type: Lambda
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161
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162 public static class Lambda
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163 {
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164 public static T CreateInstance<T>()
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165 {
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166 return InstanceCreator<T>.CreateInstance();
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167 }
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168
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169 public static List<T> CreateListInstance<T>()
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170 {
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171 return InstanceCreator<T>.CreateListInstance();
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172 }
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173
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174 public static Action<T, TValue> BuildSet<T, TValue>(string property)
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175 {
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176 string[] props = property.Split('.');
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177 Type type = typeof (T);
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178 ParameterExpression arg = Expression.Parameter(type, "x");
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179 ParameterExpression valArg = Expression.Parameter(typeof (TValue), "val");
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180 Expression expr = arg;
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181 foreach (string prop in props.Take(props.Length - 1))
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182 {
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183 // use reflection (not ComponentModel) to mirror LINQ
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184 PropertyInfo pi = type.GetProperty(prop);
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185 expr = Expression.Property(expr, pi);
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186 type = pi.PropertyType;
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187 }
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188 // final property set...
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189 PropertyInfo finalProp = type.GetProperty(props.Last());
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190 MethodInfo setter = finalProp.GetSetMethod();
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191 expr = Expression.Call(expr, setter, valArg);
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192 return Expression.Lambda<Action<T, TValue>>(expr, arg, valArg).Compile();
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193 }
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194
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195 public static Func<T, TValue> BuildGet<T, TValue>(string property)
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196 {
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197 string[] props = property.Split('.');
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198 Type type = typeof (T);
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199 ParameterExpression arg = Expression.Parameter(type, "x");
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200 Expression expr = arg;
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201 foreach (string prop in props)
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202 {
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203 // use reflection (not ComponentModel) to mirror LINQ
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204 PropertyInfo pi = type.GetProperty(prop);
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205 expr = Expression.Property(expr, pi);
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206 type = pi.PropertyType;
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207 }
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208 return Expression.Lambda<Func<T, TValue>>(expr, arg).Compile();
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209 }
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210
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211 /// <summary>
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212 /// Creates a compiled delegate function for the specified type and method name
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213 /// </summary>
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214 /// <typeparam name="TFunc">Delegate Func to create</typeparam>
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215 /// <param name="obj">Constant to get method from</param>
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216 /// <param name="methodName">Method to examine</param>
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217 /// <returns>Delegate function of the specified methodname</returns>
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218 public static TFunc CreateFunc<TFunc>(object obj, string methodName)
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219 {
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220 var args = new List<ParameterExpression>();
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221
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222 Type targetType = obj.GetType();
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223 MethodInfo minfo = targetType.GetMethod(methodName,
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224 BindingFlags.Instance | BindingFlags.Public |
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225 BindingFlags.SetProperty);
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226
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227 if (minfo != null)
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228 {
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229 ConstantExpression target = Expression.Constant(obj);
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230 foreach (ParameterInfo arg in minfo.GetParameters())
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231 args.Add(Expression.Parameter(arg.ParameterType, arg.Name));
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232 MethodCallExpression methodinvokeExpression = Expression.Call(target, minfo, args.ToArray());
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233 Expression<TFunc> lambda = Expression.Lambda<TFunc>(methodinvokeExpression, args.ToArray());
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234
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235 //now the following Lambda is created:
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236 // (TArg1, TArg2) => obj.MethodName(TArg1, TArg2);
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237
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238 return lambda.Compile();
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239 }
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240 return default(TFunc);
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241 }
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242
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243 /// <summary>
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244 /// Creates a compiled delegate function using expressions,
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245 /// the first Func{TObject,TReturn} parameter must be the constant to be passed in
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246 /// </summary>
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247 /// <typeparam name="TFunc">Delegate Func to create</typeparam>
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248 /// <param name="targetType">Type of constant to pass in to the Func</param>
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249 /// <param name="methodName">Method to examine</param>
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250 /// <returns>Delegate function of the specified methodname</returns>
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251 /// <example>
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252 /// The function Func{TType,TArg1,TArg2} with a method name of "CallMe" would create the following
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253 /// lambda:
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254 /// <code>
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255 /// (TType, TArg1, TArg2) => TType.CallMe(TArg1, TArg2);
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256 /// </code>
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257 /// </example>
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258 public static TFunc CreateFunc<TFunc>(Type targetType, string methodName)
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259 {
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260 var args = new List<ParameterExpression>();
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261 MethodInfo minfo = targetType.GetMethod(methodName,
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262 BindingFlags.Instance | BindingFlags.Public |
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263 BindingFlags.SetProperty);
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264
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265 if (minfo != null)
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266 {
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267 Type objectType = typeof (TFunc).GetGenericArguments().First();
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268 ParameterExpression targetParam = Expression.Parameter(objectType, "a");
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269
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270 if (!targetType.IsAssignableFrom(objectType))
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271 throw new InvalidCastException(string.Format("{0} cannot be cast to {1}", targetType.Name,
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272 objectType.Name));
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273
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274 UnaryExpression target = Expression.Convert(targetParam, targetType);
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275 foreach (ParameterInfo arg in minfo.GetParameters())
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276 args.Add(Expression.Parameter(arg.ParameterType, arg.Name));
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277
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278 MethodCallExpression methodinvokeExpression = Expression.Call(target, minfo, args.ToArray());
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279 Expression<TFunc> lambda = Expression.Lambda<TFunc>(methodinvokeExpression,
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280 new[] {targetParam}.Concat(args));
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281
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282 //now the following Lambda is created:
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283 // (a, TArg1, TArg2) => a.MethodName(TArg1, TArg2);
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284
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285 return lambda.Compile();
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286 }
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287 return default(TFunc);
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288 }
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289
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290 #region Nested type: InstanceCreator
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291
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292 private static class InstanceCreator<T>
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293 {
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294 public static readonly Func<T> CreateInstance =
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295 Expression.Lambda<Func<T>>(Expression.New(typeof (T))).Compile();
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296
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297 public static readonly Func<List<T>> CreateListInstance =
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298 Expression.Lambda<Func<List<T>>>(Expression.New(typeof(List<T>))).Compile();
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299 }
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300
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301 #endregion
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302 }
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303
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304 #endregion
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305
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306 #region Nested type: Remote
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307
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308 public static class Remote
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309 {
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310 public static T CreateInstance<T>()
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311 {
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312 return Activator.CreateInstance<T>();
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313 }
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314
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315 public static object CreateInstance(Type type)
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316 {
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317 return Activator.CreateInstance(type);
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318 }
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319 }
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320
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321 #endregion
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322 }
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323 } |
