/// <summary>
/// 生成指定类型的 Switch 代码块，使用差异位匹配算法。
/// </summary>
/// <typeparam name="T">指定类型</typeparam>
/// <param name="ilGen">ILGenerator IL 指令生成器</param>
/// <param name="emitLoadValue">生成加载 Switch 参数的指令的委托</param>
/// <param name="comparer">差异位比较器</param>
/// <param name="cases">case 标签块集合</param>
/// <param name="defaultLabel">默认标签块</param>
/// <param name="emitLoadItem">生成加载指定 Case 块值的指定的委托</param>
public static void DifferenceSwitch <T>(ILGenerator ilGen,
Action <ILGenerator> emitLoadValue,
Action <ILGenerator, T> emitLoadItem,
IDifferenceComparer <T> comparer,
CaseInfo <T>[] cases,
Label defaultLabel)
{
var lengthGroup = new LengthGroup <T>(cases, comparer);
if (lengthGroup.GetDepth() > DifferenceSwitchMaxDepth)
{
throw new ArgumentException("Groups too deep.");
}
var lengthCases = new CaseInfo <int> [lengthGroup.Groups.Count];
for (int i = 0; i < lengthCases.Length; i++)
{
lengthCases[i] = new CaseInfo <int>(lengthGroup.Groups[i].length, ilGen.DefineLabel())
{
Tag = lengthGroup.Groups[i].group
};
}
Switch(ilGen, (ilGen2) =>
{
emitLoadValue(ilGen2);
comparer.EmitGetLength(ilGen2);
}, lengthCases, defaultLabel);
DifferenceCasesProcess(ilGen, emitLoadValue, emitLoadItem, comparer, defaultLabel, lengthCases);
}
private static void DifferenceCasesProcess <TString>(
ILGenerator iLGen,
Action <ILGenerator> emitLoadValue,
Action <ILGenerator, TString> emitLoadItem,
IDifferenceComparer <TString> comparer,
Label defaultLabel,
CaseInfo <int>[] differenceCases)
{
foreach (var item in differenceCases)
{
iLGen.MarkLabel(item.Label);
if (item.Tag is SingleGroup <TString> singleGroup)
{
if (SwitchDoNotVerify)
{
iLGen.Branch(singleGroup.Value.Label);
}
else
{
emitLoadValue(iLGen);
emitLoadItem(iLGen, singleGroup.Value.Value);
comparer.EmitEquals(iLGen);
iLGen.BranchTrue(singleGroup.Value.Label);
iLGen.Branch(defaultLabel);
}
}
else if (item.Tag is DifferenceGroup <TString> differenceGroup)
{
var charCases = new CaseInfo <int> [differenceGroup.Groups.Count];
for (int i = 0; i < charCases.Length; i++)
{
charCases[i] = new CaseInfo <int>(differenceGroup.Groups[i].chr, iLGen.DefineLabel())
{
Tag = differenceGroup.Groups[i].group
};
}
Switch(iLGen, (ilGen2) =>
{
emitLoadValue(ilGen2);
ilGen2.LoadConstant(differenceGroup.Index);
comparer.EmitElementAt(iLGen);
}, charCases, defaultLabel);
DifferenceCasesProcess(iLGen, emitLoadValue, emitLoadItem, comparer, defaultLabel, charCases);
}
else
{
throw new NotSupportedException();
}
}
}
public BaseGroup(IDifferenceComparer <T> comparer, int sortToken)
{
Comparer = comparer;
SortToken = sortToken;
}
public SingleGroup(CaseInfo <T> value, IDifferenceComparer <T> comparer) : base(comparer, 1)
{
Value = value;
}
