这太容易了。我做了以下便利包装。它们的结构使您可以从定义方法或表达式的源代码片段构造程序集,并使用DynamicDemanager的帮助方法按名称调用它们。
该代码根据需要编译,以响应调用。添加更多方法将导致下次调用时自动重新编译。
您只提供一个方法体。如果您不想返回一个值,那么返回空值,并且不需要使用invokeMethod返回的对象。
如果你在商业代码中使用这个,请帮我一个忙,并赞扬我的工作。这个库中真正的宝石是调用支持。获取要编译的代码不是问题,而是调用。当您有一个可变长度的参数列表时,要让反射正确匹配方法签名是非常困难的。这就是存在dynamicbase的原因:编译器解析此显式声明的基类的方法绑定,使我们能够访问正确的vmt。从那里开始,所有的东西都洗出来了。
我还应该指出,这种功能使您的桌面应用程序容易受到脚本注入攻击。您应该非常注意检查脚本的源代码,或者降低生成的程序集运行时所处的信任级别。
动态基础
using System.Reflection;
namespace Dynamo
{
public abstract class DynamicBase
{
public bool EvaluateCondition(string methodName, params object[] p)
{
methodName = string.Format("__dm_{0}", methodName);
BindingFlags flags = BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic;
return (bool)GetType().InvokeMember(methodName, flags, null, this, p);
}
public object InvokeMethod(string methodName, params object[] p)
{
BindingFlags flags = BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic;
return GetType().InvokeMember(methodName, flags, null, this, p);
}
public double Transform(string functionName, params object[] p)
{
functionName = string.Format("__dm_{0}", functionName);
BindingFlags flags = BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic;
return (double)GetType().InvokeMember(functionName, flags, null, this, p);
}
}
}
动态需求管理器.cs
using System;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Diagnostics;
using System.Reflection;
using System.Text;
using Microsoft.CSharp;
namespace Dynamo
{
public static class DynamicCodeManager
{
#region internal statics and constants
static Dictionary<string, string> _conditionSnippet = new Dictionary<string, string>();
static Dictionary<string, string> _methodSnippet = new Dictionary<string, string>();
static string CodeStart = "using System;\r\nusing System.Collections.Generic;\r\n//using System.Linq;\r\nusing System.Text;\r\nusing System.Data;\r\nusing System.Reflection;\r\nusing System.CodeDom.Compiler;\r\nusing Microsoft.CSharp;\r\nnamespace Dynamo\r\n{\r\n public class Dynamic : DynamicBase\r\n {\r\n";
static string DynamicConditionPrefix = "__dm_";
static string ConditionTemplate = " bool {0}{1}(params object[] p) {{ return {2}; }}\r\n";
static string MethodTemplate = " object {0}(params object[] p) {{\r\n{1}\r\n }}\r\n";
static string CodeEnd = " }\r\n}";
static List<string> _references = new List<string>("System.dll,System.dll,System.Data.dll,System.Xml.dll,mscorlib.dll,System.Windows.Forms.dll".Split(new char[] { ',' }));
static Assembly _assembly = null;
#endregion
public static Assembly Assembly { get { return DynamicCodeManager._assembly; } }
#region manage snippets
public static void Clear()
{
_methodSnippet.Clear();
_conditionSnippet.Clear();
_assembly = null;
}
public static void Clear(string name)
{
if (_conditionSnippet.ContainsKey(name))
{
_assembly = null;
_conditionSnippet.Remove(name);
}
else if (_methodSnippet.ContainsKey(name))
{
_assembly = null;
_methodSnippet.Remove(name);
}
}
public static void AddCondition(string conditionName, string booleanExpression)
{
if (_conditionSnippet.ContainsKey(conditionName))
throw new InvalidOperationException(string.Format("There is already a condition called '{0}'", conditionName));
StringBuilder src = new StringBuilder(CodeStart);
src.AppendFormat(ConditionTemplate, DynamicConditionPrefix, conditionName, booleanExpression);
src.Append(CodeEnd);
Compile(src.ToString()); //if the condition is invalid an exception will occur here
_conditionSnippet[conditionName] = booleanExpression;
_assembly = null;
}
public static void AddMethod(string methodName, string methodSource)
{
if (_methodSnippet.ContainsKey(methodName))
throw new InvalidOperationException(string.Format("There is already a method called '{0}'", methodName));
if (methodName.StartsWith(DynamicConditionPrefix))
throw new InvalidOperationException(string.Format("'{0}' is not a valid method name because the '{1}' prefix is reserved for internal use with conditions", methodName, DynamicConditionPrefix));
StringBuilder src = new StringBuilder(CodeStart);
src.AppendFormat(MethodTemplate, methodName, methodSource);
src.Append(CodeEnd);
Trace.TraceError("SOURCE\r\n{0}", src);
Compile(src.ToString()); //if the condition is invalid an exception will occur here
_methodSnippet[methodName] = methodSource;
_assembly = null;
}
#endregion
#region use snippets
public static object InvokeMethod(string methodName, params object[] p)
{
DynamicBase _dynamicMethod = null;
if (_assembly == null)
{
Compile();
_dynamicMethod = _assembly.CreateInstance("Dynamo.Dynamic") as DynamicBase;
}
return _dynamicMethod.InvokeMethod(methodName, p);
}
public static bool Evaluate(string conditionName, params object[] p)
{
DynamicBase _dynamicCondition = null;
if (_assembly == null)
{
Compile();
_dynamicCondition = _assembly.CreateInstance("Dynamo.Dynamic") as DynamicBase;
}
return _dynamicCondition.EvaluateCondition(conditionName, p);
}
public static double Transform(string functionName, params object[] p)
{
DynamicBase _dynamicCondition = null;
if (_assembly == null)
{
Compile();
_dynamicCondition = _assembly.CreateInstance("Dynamo.Dynamic") as DynamicBase;
}
return _dynamicCondition.Transform(functionName, p);
}
#endregion
#region support routines
public static string ProduceConditionName(Guid conditionId)
{
StringBuilder cn = new StringBuilder();
foreach (char c in conditionId.ToString().ToCharArray()) if (char.IsLetterOrDigit(c)) cn.Append(c);
string conditionName = cn.ToString();
return string.Format("_dm_{0}",cn);
}
private static void Compile()
{
if (_assembly == null)
{
StringBuilder src = new StringBuilder(CodeStart);
foreach (KeyValuePair<string, string> kvp in _conditionSnippet)
src.AppendFormat(ConditionTemplate, DynamicConditionPrefix, kvp.Key, kvp.Value);
foreach (KeyValuePair<string, string> kvp in _methodSnippet)
src.AppendFormat(MethodTemplate, kvp.Key, kvp.Value);
src.Append(CodeEnd);
Trace.TraceError("SOURCE\r\n{0}", src);
_assembly = Compile(src.ToString());
}
}
private static Assembly Compile(string sourceCode)
{
CompilerParameters cp = new CompilerParameters();
cp.ReferencedAssemblies.AddRange(_references.ToArray());
cp.ReferencedAssemblies.Add(Assembly.GetExecutingAssembly().ManifestModule.FullyQualifiedName);
cp.CompilerOptions = "/target:library /optimize";
cp.GenerateExecutable = false;
cp.GenerateInMemory = true;
CompilerResults cr = (new CSharpCodeProvider()).CompileAssemblyFromSource(cp, sourceCode);
if (cr.Errors.Count > 0) throw new CompilerException(cr.Errors);
return cr.CompiledAssembly;
}
#endregion
public static bool HasItem(string methodName)
{
return _conditionSnippet.ContainsKey(methodName) || _methodSnippet.ContainsKey(methodName);
}
}
}
