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namespace System.Web.UI.WebControls {
/// <summary>
/// This class tracks the values of SelectMethod parameters of ModelDataSourceView that use a custom value provider across multiple page requests.
/// </summary>
internal sealed class MethodParameterValue : IStateManager {
private MethodParametersDictionary _owner;
private bool _tracking;
private StateBag _viewState;
private static readonly string s_valueViewStateKey = "ParameterValue";
/// <devdoc>
/// Tells the Parameter the dictionary it belongs to
/// </devdoc>
internal void SetOwner(MethodParametersDictionary owner) {
_owner = owner;
}
/// <devdoc>
/// Raises the ParameterChanged event.
/// </devdoc>
private void OnParameterChanged() {
if (_owner != null) {
_owner.CallOnParametersChanged();
}
}
internal void UpdateValue(object newValue) {
object oldValue = ViewState[s_valueViewStateKey];
ViewState[s_valueViewStateKey] = newValue;
if ((newValue == null && oldValue != null) || (newValue != null && !newValue.Equals(oldValue))) {
OnParameterChanged();
}
}
/// <devdoc>
/// Indicates whether the MethodParameter is tracking view state.
/// </devdoc>
private bool IsTrackingViewState {
get {
return _tracking;
}
}
/// <devdoc>
/// Indicates a dictionary of state information that allows you to save and restore
/// the state of a MethodParameter across multiple requests for the same page.
/// </devdoc>
private StateBag ViewState {
get {
if (_viewState == null) {
_viewState = new StateBag();
if (_tracking)
_viewState.TrackViewState();
}
return _viewState;
}
}
/// <devdoc>
/// Loads view state.
/// </devdoc>
private void LoadViewState(object savedState) {
if (savedState != null) {
ViewState.LoadViewState(savedState);
}
}
/// <devdoc>
/// Saves view state.
/// </devdoc>
private object SaveViewState() {
return (_viewState != null) ? _viewState.SaveViewState() : null;
}
/// <devdoc>
/// Tells the MethodParameter to start tracking property changes.
/// </devdoc>
private void TrackViewState() {
_tracking = true;
if (_viewState != null) {
_viewState.TrackViewState();
}
}
#region Implementation of IStateManager
bool IStateManager.IsTrackingViewState {
get {
return IsTrackingViewState;
}
}
void IStateManager.LoadViewState(object savedState) {
LoadViewState(savedState);
}
object IStateManager.SaveViewState() {
return SaveViewState();
}
void IStateManager.TrackViewState() {
TrackViewState();
}
#endregion
}
}
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