29 lines
1.1 KiB
C#
29 lines
1.1 KiB
C#
using System;
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using System.Linq;
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using System.Linq.Expressions;
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namespace DJ.Helper
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{
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public static class PredicateBuilder
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{
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public static Expression<Func<T, bool>> True<T> () { return f => true; }
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public static Expression<Func<T, bool>> False<T> () { return f => false; }
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public static Expression<Func<T, bool>> Or<T> (this Expression<Func<T, bool>> expr1,
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Expression<Func<T, bool>> expr2)
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{
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var invokedExpr = Expression.Invoke (expr2, expr1.Parameters.Cast<Expression> ());
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return Expression.Lambda<Func<T, bool>>
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(Expression.OrElse (expr1.Body, invokedExpr), expr1.Parameters);
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}
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public static Expression<Func<T, bool>> And<T> (this Expression<Func<T, bool>> expr1,
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Expression<Func<T, bool>> expr2)
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{
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var invokedExpr = Expression.Invoke (expr2, expr1.Parameters.Cast<Expression> ());
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return Expression.Lambda<Func<T, bool>>
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(Expression.AndAlso (expr1.Body, invokedExpr), expr1.Parameters);
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}
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}
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}
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