/// <summary>
/// 实例。
/// </summary>
/// <param name="constant">常量。</param>
public ICaseHandler Case(ConstantAst constant)
{
if (constant is null)
{
throw new ArgumentNullException(nameof(constant));
}
IPrivateCaseHandler handler;
switch (switchValueKind)
{
case MySwitchValueKind.Arithmetic when IsArithmetic(constant.RuntimeType):
handler = new SwitchCaseArithmeticAst(constant, RuntimeType);
break;
case MySwitchValueKind.RuntimeType:
throw new AstException("当前流程控制为类型转换，请使用“{Case(VariableAst variable)}”方法处理！");
case MySwitchValueKind.Equality:
var types = new Type[2] {
switchValueType, constant.RuntimeType
};
MethodInfo comparison = switchValueType.GetMethod("op_Equality", BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic, null, types, null);
if (comparison is null && !EmitUtils.AreEquivalent(switchValueType, constant.RuntimeType))
{
comparison = constant.RuntimeType.GetMethod("op_Equality", BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic, null, types, null);
}
if (comparison is null && switchValueType.IsAssignableFrom(typeof(IEquatable <>).MakeGenericType(constant.RuntimeType)))
{
comparison = switchValueType.GetMethod("Equals", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null, new Type[] { constant.RuntimeType }, null);
}
if (comparison is null)
{
throw new InvalidOperationException($"未找到“{constant.RuntimeType}”和“{switchValueType}”有效的比较函数!");
}
handler = new SwitchCaseEqualityAst(constant, comparison, RuntimeType);
break;
default:
throw new NotSupportedException();
}
switchCases.Add(handler);
return(handler);
}
public SwitchCaseArithmeticAst(ConstantAst constant, Type returnType) : base(returnType)
{
this.constant = constant;
}
public SwitchCase(ConstantAst value, AstExpression body)
{
Value = value;
Body = body;
}
public SwitchCaseEqualityAst(ConstantAst constant, MethodInfo comparison, Type returnType) : base(returnType)
{
this.constant = constant;
this.comparison = comparison;
}