43 lines
2.1 KiB
C#
43 lines
2.1 KiB
C#
namespace LeanCloud.Storage.Internal {
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/// <summary>
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/// A AVFieldOperation represents a modification to a value in a AVObject.
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/// For example, setting, deleting, or incrementing a value are all different kinds of
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/// AVFieldOperations. AVFieldOperations themselves can be considered to be
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/// immutable.
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/// </summary>
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public interface IAVFieldOperation {
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/// <summary>
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/// Converts the AVFieldOperation to a data structure that can be converted to JSON and sent to
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/// LeanCloud as part of a save operation.
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/// </summary>
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/// <returns>An object to be JSONified.</returns>
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object Encode();
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/// <summary>
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/// Returns a field operation that is composed of a previous operation followed by
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/// this operation. This will not mutate either operation. However, it may return
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/// <code>this</code> if the current operation is not affected by previous changes.
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/// For example:
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/// {increment by 2}.MergeWithPrevious({set to 5}) -> {set to 7}
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/// {set to 5}.MergeWithPrevious({increment by 2}) -> {set to 5}
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/// {add "foo"}.MergeWithPrevious({delete}) -> {set to ["foo"]}
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/// {delete}.MergeWithPrevious({add "foo"}) -> {delete} /// </summary>
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/// <param name="previous">The most recent operation on the field, or null if none.</param>
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/// <returns>A new AVFieldOperation or this.</returns>
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IAVFieldOperation MergeWithPrevious(IAVFieldOperation previous);
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/// <summary>
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/// Returns a new estimated value based on a previous value and this operation. This
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/// value is not intended to be sent to LeanCloud, but it is used locally on the client to
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/// inspect the most likely current value for a field.
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///
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/// The key and object are used solely for AVRelation to be able to construct objects
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/// that refer back to their parents.
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/// </summary>
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/// <param name="oldValue">The previous value for the field.</param>
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/// <param name="key">The key that this value is for.</param>
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/// <returns>The new value for the field.</returns>
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object Apply(object oldValue, string key);
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}
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}
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