79 lines
2.4 KiB
C#
79 lines
2.4 KiB
C#
namespace System
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{
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internal struct ParamsArray
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{
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// Sentinel fixed-length arrays eliminate the need for a "count" field keeping this
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// struct down to just 4 fields. These are only used for their "Length" property,
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// that is, their elements are never set or referenced.
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private static readonly object[] oneArgArray = new object[1];
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private static readonly object[] twoArgArray = new object[2];
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private static readonly object[] threeArgArray = new object[3];
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private readonly object arg0;
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private readonly object arg1;
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private readonly object arg2;
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// After construction, the first three elements of this array will never be accessed
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// because the indexer will retrieve those values from arg0, arg1, and arg2.
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private readonly object[] args;
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public ParamsArray(object arg0)
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{
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this.arg0 = arg0;
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this.arg1 = null;
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this.arg2 = null;
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// Always assign this.args to make use of its "Length" property
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this.args = oneArgArray;
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}
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public ParamsArray(object arg0, object arg1)
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{
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this.arg0 = arg0;
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this.arg1 = arg1;
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this.arg2 = null;
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// Always assign this.args to make use of its "Length" property
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this.args = twoArgArray;
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}
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public ParamsArray(object arg0, object arg1, object arg2)
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{
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this.arg0 = arg0;
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this.arg1 = arg1;
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this.arg2 = arg2;
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// Always assign this.args to make use of its "Length" property
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this.args = threeArgArray;
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}
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public ParamsArray(object[] args)
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{
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int len = args.Length;
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this.arg0 = len > 0 ? args[0] : null;
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this.arg1 = len > 1 ? args[1] : null;
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this.arg2 = len > 2 ? args[2] : null;
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this.args = args;
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}
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public int Length
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{
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get { return this.args.Length; }
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}
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public object this[int index]
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{
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get { return index == 0 ? this.arg0 : GetAtSlow(index); }
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}
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private object GetAtSlow(int index)
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{
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if (index == 1)
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return this.arg1;
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if (index == 2)
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return this.arg2;
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return this.args[index];
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}
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}
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}
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