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namespace System.Web.UI.WebControls.Expressions {
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Linq.Expressions;
using System.Web.Resources;
using System.Web.UI;
using System.Web.UI.WebControls;
public class RangeExpression : ParameterDataSourceExpression {
public string DataField {
get {
return (string)ViewState["DataField"] ?? String.Empty;
}
set {
ViewState["DataField"] = value;
}
}
public RangeType MinType {
get {
object o = ViewState["MinType"];
return o != null ? (RangeType)o : RangeType.None;
}
set {
ViewState["MinType"] = value;
}
}
public RangeType MaxType {
get {
object o = ViewState["MaxType"];
return o != null ? (RangeType)o : RangeType.None;
}
set {
ViewState["MaxType"] = value;
}
}
internal virtual new IOrderedDictionary GetValues() {
return Parameters.GetValues(Context, Owner);
}
public override IQueryable GetQueryable(IQueryable source) {
if (source == null) {
return null;
}
if (String.IsNullOrEmpty(DataField)) {
throw new InvalidOperationException(AtlasWeb.Expressions_DataFieldRequired);
}
IOrderedDictionary values = GetValues();
ParameterExpression parameterExpression = Expression.Parameter(source.ElementType, String.Empty);
Expression properyExpression = ExpressionHelper.GetValue(ExpressionHelper.CreatePropertyExpression(parameterExpression, DataField));
if (MinType == RangeType.None && MaxType == RangeType.None) {
throw new InvalidOperationException(AtlasWeb.RangeExpression_RangeTypeMustBeSpecified);
}
Expression minExpression = null;
Expression maxExpression = null;
if (MinType != RangeType.None) {
if (values.Count == 0) {
throw new InvalidOperationException(AtlasWeb.RangeExpression_MinimumValueRequired);
}
if (values[0] != null) {
minExpression = GetMinRangeExpression(properyExpression, values[0], MinType);
}
}
if (MaxType != RangeType.None) {
if (values.Count == 0 || ((minExpression != null) && (values.Count == 1))) {
throw new InvalidOperationException(AtlasWeb.RangeExpression_MaximumValueRequired);
}
object maxValue = minExpression == null ? values[0] : values[1];
if (maxValue != null) {
maxExpression = GetMaxRangeExpression(properyExpression, maxValue, MaxType);
}
}
if ((maxExpression == null) && (minExpression == null)) {
return null;
}
Expression rangeExpression = CreateRangeExpressionBody(minExpression, maxExpression);
return ExpressionHelper.Where(source, Expression.Lambda(rangeExpression, parameterExpression));
}
private static Expression GetMinRangeExpression(Expression propertyExpression, object value, RangeType rangeType) {
ConstantExpression constantValue = Expression.Constant(ExpressionHelper.BuildObjectValue(value, propertyExpression.Type));
switch (rangeType) {
case RangeType.Exclusive:
return Expression.GreaterThan(propertyExpression, constantValue);
case RangeType.None:
return null;
case RangeType.Inclusive:
return Expression.GreaterThanOrEqual(propertyExpression, constantValue);
default:
Debug.Fail("shouldn't get here!");
return null;
}
}
private static Expression GetMaxRangeExpression(Expression propertyExpression, object value, RangeType rangeType) {
ConstantExpression constantValue = Expression.Constant(ExpressionHelper.BuildObjectValue(value, propertyExpression.Type));
switch (rangeType) {
case RangeType.Exclusive:
return Expression.LessThan(propertyExpression, constantValue);
case RangeType.None:
return null;
case RangeType.Inclusive:
return Expression.LessThanOrEqual(propertyExpression, constantValue);
default:
Debug.Fail("shouldn't get here!");
return null;
}
}
private static Expression CreateRangeExpressionBody(Expression minExpression, Expression maxExpression) {
if (minExpression == null && maxExpression == null) {
return null;
}
if (minExpression == null) {
return maxExpression;
}
if (maxExpression == null) {
return minExpression;
}
return Expression.AndAlso(minExpression, maxExpression);
}
}
}
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