116 lines
4.8 KiB
C#
116 lines
4.8 KiB
C#
/*******************************************************************************
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* Copyright © 2016 WaterCloud.Framework 版权所有
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* Author: WaterCloud
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* Description: WaterCloud快速开发平台
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* Website：
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*********************************************************************************/
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Linq.Expressions;
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using System.Reflection;
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namespace WaterCloud.Code
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{
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public static partial class ExtLinq
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{
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public static Expression Property(this Expression expression, string propertyName)
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{
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return Expression.Property(expression, propertyName);
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}
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public static Expression AndAlso(this Expression left, Expression right)
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{
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return Expression.AndAlso(left, right);
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}
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public static Expression Call(this Expression instance, string methodName, params Expression[] arguments)
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{
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return Expression.Call(instance, instance.Type.GetMethod(methodName), arguments);
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}
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public static Expression GreaterThan(this Expression left, Expression right)
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{
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return Expression.GreaterThan(left, right);
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}
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public static Expression<T> ToLambda<T>(this Expression body, params ParameterExpression[] parameters)
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{
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return Expression.Lambda<T>(body, parameters);
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}
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public static Expression<Func<T, bool>> True<T>() { return param => true; }
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public static Expression<Func<T, bool>> False<T>() { return param => false; }
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public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
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{
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return first.Compose(second, Expression.AndAlso);
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}
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public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
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{
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return first.Compose(second, Expression.OrElse);
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}
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public static Expression<T> Compose<T>(this Expression<T> first, Expression<T> second, Func<Expression, Expression, Expression> merge)
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{
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var map = first.Parameters
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.Select((f, i) => new { f, s = second.Parameters[i] })
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.ToDictionary(p => p.s, p => p.f);
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var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);
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return Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
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}
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private class ParameterRebinder : ExpressionVisitor
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{
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readonly Dictionary<ParameterExpression, ParameterExpression> map;
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/// <summary>
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/// Initializes a new instance of the <see cref="ParameterRebinder"/> class.
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/// </summary>
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/// <param name="map">The map.</param>
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ParameterRebinder(Dictionary<ParameterExpression, ParameterExpression> map)
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{
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this.map = map ?? new Dictionary<ParameterExpression, ParameterExpression>();
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}
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/// <summary>
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/// Replaces the parameters.
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/// </summary>
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/// <param name="map">The map.</param>
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/// <param name="exp">The exp.</param>
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/// <returns>Expression</returns>
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public static Expression ReplaceParameters(Dictionary<ParameterExpression, ParameterExpression> map, Expression exp)
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{
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return new ParameterRebinder(map).Visit(exp);
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}
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protected override Expression VisitParameter(ParameterExpression p)
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{
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ParameterExpression replacement;
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if (map.TryGetValue(p, out replacement))
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{
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p = replacement;
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}
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return base.VisitParameter(p);
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}
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}
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public static ParameterExpression CreateLambdaParam<T>(string name)
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{
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return Expression.Parameter(typeof(T), name);
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}
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/// <summary>
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/// 创建完整的lambda
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/// </summary>
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public static LambdaExpression GenerateLambda(this ParameterExpression param, Expression body)
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{
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//c=>c.XXX=="XXX"
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return Expression.Lambda(body, param);
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}
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public static Expression<Func<T, bool>> GenerateTypeLambda<T>(this ParameterExpression param, Expression body)
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{
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return (Expression<Func<T, bool>>)(param.GenerateLambda(body));
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}
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public static Expression Or(this Expression expression, Expression expressionRight)
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{
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return Expression.Or(expression, expressionRight);
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}
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public static Expression And(this Expression expression, Expression expressionRight)
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{
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return Expression.And(expression, expressionRight);
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}
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}
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}
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