using System.Collections.Concurrent;
using System.Linq.Expressions;
using System.Reflection;
namespace Serein.Flow.Tool
{
///
/// 对于实例创建的表达式树反射
///
public static class ExpressionHelper
{
///
/// 缓存表达式树反射方法
///
private static ConcurrentDictionary Cache { get; } = new ConcurrentDictionary();
public static List GetCacheKey()
{
return [.. Cache.Keys];
}
#region 基于类型的表达式反射构建委托
#region 属性、字段的委托创建(表达式反射)
///
/// 动态获取属性值
///
public static Delegate PropertyGetter(Type type, string propertyName)
{
string cacheKey = $"{type.FullName}.{propertyName}.Getter";
return Cache.GetOrAdd(cacheKey, _ => CreateGetterDelegate(type, propertyName));
}
///
/// 动态获取属性值
///
private static Delegate CreateGetterDelegate(Type type, string propertyName)
{
var parameter = Expression.Parameter(typeof(object), "instance");
var property = Expression.Property(Expression.Convert(parameter, type), propertyName);
var lambda = Expression.Lambda(Expression.Convert(property, typeof(object)), parameter);
return lambda.Compile();
}
///
/// 动态设置属性值
///
public static Delegate PropertySetter(Type type, string propertyName)
{
string cacheKey = $"{type.FullName}.{propertyName}.Setter";
return Cache.GetOrAdd(cacheKey, _ => CreateSetterDelegate(type, propertyName));
}
///
/// 动态设置属性值
///
private static Delegate CreateSetterDelegate(Type type, string propertyName)
{
var parameter = Expression.Parameter(typeof(object), "instance");
var value = Expression.Parameter(typeof(object), "value");
var property = Expression.Property(Expression.Convert(parameter, type), propertyName);
var assign = Expression.Assign(property, Expression.Convert(value, property.Type));
var lambda = Expression.Lambda(assign, parameter, value);
return lambda.Compile();
}
///
/// 动态获取字段值
///
public static Delegate FieldGetter(Type type, string fieldName)
{
string cacheKey = $"{type.FullName}.{fieldName}.FieldGetter";
return Cache.GetOrAdd(cacheKey, _ => CreateFieldGetterDelegate(type, fieldName));
}
///
/// 动态获取字段值
///
private static Delegate CreateFieldGetterDelegate(Type type, string fieldName)
{
var parameter = Expression.Parameter(typeof(object), "instance");
var field = Expression.Field(Expression.Convert(parameter, type), fieldName);
var lambda = Expression.Lambda(Expression.Convert(field, typeof(object)), parameter);
return lambda.Compile();
}
///
/// 动态设置字段值
///
public static Delegate FieldSetter(Type type, string fieldName)
{
string cacheKey = $"{type.FullName}.{fieldName}.FieldSetter";
return Cache.GetOrAdd(cacheKey, _ => CreateFieldSetterDelegate(type, fieldName));
}
///
/// 动态设置字段值
///
private static Delegate CreateFieldSetterDelegate(Type type, string fieldName)
{
var parameter = Expression.Parameter(typeof(object), "instance");
var value = Expression.Parameter(typeof(object), "value");
var field = Expression.Field(Expression.Convert(parameter, type), fieldName);
var assign = Expression.Assign(field, Expression.Convert(value, field.Type));
var lambda = Expression.Lambda(assign, parameter, value);
return lambda.Compile();
}
#endregion
///
/// 表达式树构建无参数,无返回值方法
///
public static Delegate MethodCaller(Type type, MethodInfo methodInfo)
{
string cacheKey = $"{type.FullName}.{methodInfo.Name}.MethodCaller";
return Cache.GetOrAdd(cacheKey, _ => CreateMethodCallerDelegate(type, methodInfo));
}
///
/// 表达式树构建无参数,无返回值方法
///
private static Delegate CreateMethodCallerDelegate(Type type, MethodInfo methodInfo)
{
var parameter = Expression.Parameter(typeof(object), "instance");
var methodCall = Expression.Call(Expression.Convert(parameter, type), methodInfo);
var lambda = Expression.Lambda(methodCall, parameter);
// Action