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- 增加 LambdaExpression 扩展方法 And/Or/Not 快速拼接表达式；

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28810
2019-06-20 17:56:07 +08:00
parent 06ff0a4da2
commit 3e8fed416d
11 changed files with 190 additions and 8 deletions
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98
FreeSql/Extensions/LambadaExpressionExtensions.cs Normal file
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@ -0,0 +1,98 @@
using FreeSql;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
namespace System.Linq.Expressions {
public static partial class LambadaExpressionExtensions {
/// <summary>
/// 使用 and 拼接两个 lambda 表达式
/// </summary>
/// <returns></returns>
public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> exp1, Expression<Func<T, bool>> exp2) => And(exp1, true, exp2);
/// <summary>
/// 使用 and 拼接两个 lambda 表达式
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="exp1"></param>
/// <param name="condition">true 时生效</param>
/// <param name="exp2"></param>
/// <returns></returns>
public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> exp1, bool condition, Expression<Func<T, bool>> exp2) {
if (condition == false) return exp1;
if (exp1 == null) return exp2;
if (exp2 == null) return exp1;
ParameterExpression newParameter = Expression.Parameter(typeof(T), "c");
NewExpressionVisitor visitor = new NewExpressionVisitor(newParameter);
var left = visitor.Replace(exp1.Body);
var right = visitor.Replace(exp2.Body);
var body = Expression.AndAlso(left, right);
return Expression.Lambda<Func<T, bool>>(body, newParameter);
}
/// <summary>
/// 使用 or 拼接两个 lambda 表达式
/// </summary>
/// <returns></returns>
public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> exp1, Expression<Func<T, bool>> exp2) => Or(exp1, true, exp2);
/// <summary>
/// 使用 or 拼接两个 lambda 表达式
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="exp1"></param>
/// <param name="condition">true 时生效</param>
/// <param name="exp2"></param>
/// <returns></returns>
public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> exp1, bool condition, Expression<Func<T, bool>> exp2) {
if (condition == false) return exp1;
if (exp1 == null) return exp2;
if (exp2 == null) return exp1;
ParameterExpression newParameter = Expression.Parameter(typeof(T), "c");
NewExpressionVisitor visitor = new NewExpressionVisitor(newParameter);
var left = visitor.Replace(exp1.Body);
var right = visitor.Replace(exp2.Body);
var body = Expression.OrElse(left, right);
return Expression.Lambda<Func<T, bool>>(body, newParameter);
}
/// <summary>
/// 将 lambda 表达式取反
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="exp"></param>
/// <param name="condition">true 时生效</param>
/// <returns></returns>
public static Expression<Func<T, bool>> Not<T>(this Expression<Func<T, bool>> exp, bool condition = true) {
if (condition == false) return exp;
if (exp == null) return null;
var candidateExpr = exp.Parameters[0];
var body = Expression.Not(exp.Body);
return Expression.Lambda<Func<T, bool>>(body, candidateExpr);
}
}
internal class NewExpressionVisitor : ExpressionVisitor {
public ParameterExpression _newParameter { get; private set; }
public NewExpressionVisitor(ParameterExpression param) {
this._newParameter = param;
}
public Expression Replace(Expression exp) {
return this.Visit(exp);
}
protected override Expression VisitParameter(ParameterExpression node) {
return this._newParameter;
}
}
}

2
FreeSql/FreeSql.csproj
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@ -2,7 +2,7 @@
<PropertyGroup>
<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
<Version>0.6.11</Version>
<Version>0.6.12</Version>
<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
<Authors>YeXiangQin</Authors>
<Description>FreeSql is the most convenient ORM in dotnet. It supports Mysql, Postgresql, SqlServer, Oracle and Sqlite.</Description>

41
FreeSql/FreeSql.xml
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@ -2349,6 +2349,47 @@
<param name="that"></param>
<returns></returns>
</member>
<member name="M:System.Linq.Expressions.LambadaExpressionExtensions.And``1(System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}},System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}})">
<summary>
使用 and 拼接两个 lambda 表达式
</summary>
<returns></returns>
</member>
<member name="M:System.Linq.Expressions.LambadaExpressionExtensions.And``1(System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}},System.Boolean,System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}})">
<summary>
使用 and 拼接两个 lambda 表达式
</summary>
<typeparam name="T"></typeparam>
<param name="exp1"></param>
<param name="condition">true 时生效</param>
<param name="exp2"></param>
<returns></returns>
</member>
<member name="M:System.Linq.Expressions.LambadaExpressionExtensions.Or``1(System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}},System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}})">
<summary>
使用 or 拼接两个 lambda 表达式
</summary>
<returns></returns>
</member>
<member name="M:System.Linq.Expressions.LambadaExpressionExtensions.Or``1(System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}},System.Boolean,System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}})">
<summary>
使用 or 拼接两个 lambda 表达式
</summary>
<typeparam name="T"></typeparam>
<param name="exp1"></param>
<param name="condition">true 时生效</param>
<param name="exp2"></param>
<returns></returns>
</member>
<member name="M:System.Linq.Expressions.LambadaExpressionExtensions.Not``1(System.Linq.Expressions.Expression{System.Func{``0,System.Boolean}},System.Boolean)">
<summary>
将 lambda 表达式取反
</summary>
<typeparam name="T"></typeparam>
<param name="exp"></param>
<param name="condition">true 时生效</param>
<returns></returns>
</member>
<member name="M:FreeUtil.NewMongodbId">
<summary>
生成类似Mongodb的ObjectId有序、不重复Guid