110 lines
3.8 KiB
C#
110 lines
3.8 KiB
C#
namespace System.Web.UI.WebControls.Expressions {
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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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internal static class ExpressionHelper {
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public static Expression GetValue(Expression exp) {
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Type realType = GetUnderlyingType(exp.Type);
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if (realType == exp.Type) {
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return exp;
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}
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return Expression.Convert(exp, realType);
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}
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public static Type GetUnderlyingType(Type type) {
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// Get the type from Nullable types
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if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>)) {
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return type.GetGenericArguments()[0];
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}
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return type;
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}
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public static object BuildObjectValue(object value, Type type) {
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return System.Web.UI.WebControls.DataSourceHelper.BuildObjectValue(value, type, String.Empty);
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}
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public static Expression CreatePropertyExpression(Expression parameterExpression, string propertyName) {
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if (parameterExpression == null) {
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return null;
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}
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if (String.IsNullOrEmpty(propertyName)) {
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return null;
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}
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Expression propExpression = null;
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string[] props = propertyName.Split('.');
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foreach (var p in props) {
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if (propExpression == null) {
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propExpression = Expression.PropertyOrField(parameterExpression, p);
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}
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else {
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propExpression = Expression.PropertyOrField(propExpression, p);
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}
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}
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return propExpression;
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}
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public static IQueryable Where(this IQueryable source, LambdaExpression lambda) {
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return Call(source, "Where", lambda, source.ElementType);
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}
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public static IQueryable Call(this IQueryable source, string queryMethod, Type[] genericArgs, params Expression[] arguments) {
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if (source == null) {
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throw new ArgumentNullException("source");
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}
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return source.Provider.CreateQuery(
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Expression.Call(
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typeof(Queryable), queryMethod,
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genericArgs,
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arguments));
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}
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public static IQueryable Call(this IQueryable source, string queryableMethod, LambdaExpression lambda, params Type[] genericArgs) {
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if (source == null) {
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throw new ArgumentNullException("source");
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}
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return source.Provider.CreateQuery(
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Expression.Call(
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typeof(Queryable), queryableMethod,
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genericArgs,
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source.Expression, Expression.Quote(lambda)));
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}
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public static Expression Or(IEnumerable<Expression> expressions) {
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Expression orExpression = null;
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foreach (Expression e in expressions) {
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if (e == null) {
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continue;
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}
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if (orExpression == null) {
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orExpression = e;
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}
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else {
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orExpression = Expression.OrElse(orExpression, e);
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}
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}
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return orExpression;
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}
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public static Expression And(IEnumerable<Expression> expressions) {
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Expression andExpression = null;
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foreach (Expression e in expressions) {
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if (e == null) {
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continue;
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}
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if (andExpression == null) {
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andExpression = e;
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}
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else {
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andExpression = Expression.AndAlso(andExpression, e);
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}
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}
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return andExpression;
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}
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}
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}
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