protected static TDelegate BuildDeserializeDelegateExpressions <TDelegate, TReturn>(ParameterExpression inputExpression, Expression nameSpanExpression)
{
var nameSpan = Expression.Variable(typeof(ReadOnlySpan <TSymbol>), "nameSpan");
var returnValue = Expression.Variable(typeof(TReturn), "returnValue");
var lengthParameter = Expression.Variable(typeof(int), "length");
var endOfBlockLabel = Expression.Label();
var assignNameSpan = Expression.Assign(nameSpan, nameSpanExpression);
var lengthExpression = Expression.Assign(lengthParameter, Expression.PropertyOrField(nameSpan, "Length"));
var byteNameSpan = Expression.Variable(typeof(ReadOnlySpan <byte>), "byteNameSpan");
var parameters = new List <ParameterExpression> {
nameSpan, lengthParameter, returnValue
};
if (typeof(TSymbol) == typeof(char))
{
var asBytesMethodInfo = FindGenericMethod(typeof(MemoryMarshal), nameof(MemoryMarshal.AsBytes), BindingFlags.Public | BindingFlags.Static,
typeof(char), typeof(ReadOnlySpan <>));
nameSpanExpression = Expression.Call(null, asBytesMethodInfo, assignNameSpan);
assignNameSpan = Expression.Assign(byteNameSpan, nameSpanExpression);
parameters.Add(byteNameSpan);
}
else
{
byteNameSpan = nameSpan;
}
var memberInfos = new List <JsonMemberInfo>();
var dict = new Dictionary <string, TReturn>();
foreach (var name in Enum.GetNames(typeof(T)))
{
var formattedValue = GetFormattedValue(name);
memberInfos.Add(new JsonMemberInfo(name, typeof(T), null, formattedValue, false, true, false, null, null));
var value = Enum.Parse(typeof(T), name);
dict.Add(name, (TReturn)Convert.ChangeType(value, typeof(TReturn)));
}
Expression MatchExpressionFunctor(JsonMemberInfo memberInfo)
{
var enumValue = dict[memberInfo.MemberName];
return(Expression.Assign(returnValue, Expression.Constant(enumValue)));
}
var returnTarget = Expression.Label(returnValue.Type);
var returnLabel = Expression.Label(returnTarget, returnValue);
var expressions = new List <Expression>
{
assignNameSpan,
lengthExpression,
MemberComparisonBuilder.Build <TSymbol>(memberInfos, 0, lengthParameter, byteNameSpan, endOfBlockLabel, MatchExpressionFunctor),
Expression.Throw(Expression.Constant(new InvalidOperationException())),
Expression.Label(endOfBlockLabel),
returnLabel
};
var blockExpression = Expression.Block(parameters, expressions);
var lambdaExpression =
Expression.Lambda <TDelegate>(blockExpression, inputExpression);
return(lambdaExpression.Compile());
}
/// <summary>
/// Creates the deserializer for both utf8 and utf16
/// There should not be a large difference between utf8 and utf16 besides member names
/// </summary>
protected static DeserializeDelegate <T, TSymbol> BuildDeserializeDelegate <T, TSymbol, TResolver>()
where TResolver : IJsonFormatterResolver <TSymbol, TResolver>, new() where TSymbol : struct
{
var resolver = StandardResolvers.GetResolver <TSymbol, TResolver>();
var objectDescription = resolver.GetObjectDescription <T>();
var memberInfos = objectDescription.Where(a => a.CanWrite).ToList();
var readerParameter = Expression.Parameter(typeof(JsonReader <TSymbol>).MakeByRefType(), "reader");
// can't deserialize abstract and only support interfaces based on IEnumerable<T> (this includes, IList, IReadOnlyList, IDictionary et al.)
foreach (var memberInfo in memberInfos)
{
var memberType = memberInfo.MemberType;
if (memberType.IsAbstract)
{
if (memberType.TryGetTypeOfGenericInterface(typeof(IEnumerable <>), out _))
{
continue;
}
return(Expression
.Lambda <DeserializeDelegate <T, TSymbol> >(Expression.Block(
Expression.Throw(Expression.Constant(new NotSupportedException($"{typeof(T).Name} contains abstract members."))),
Expression.Default(typeof(T))),
readerParameter).Compile());
}
}
if (typeof(T).IsAbstract)
{
return(Expression.Lambda <DeserializeDelegate <T, TSymbol> >(Expression.Default(typeof(T)), readerParameter).Compile());
}
if (memberInfos.Count == 0)
{
Expression createExpression = null;
if (typeof(T).IsClass)
{
var ci = typeof(T).GetConstructor(Type.EmptyTypes);
if (ci != null)
{
createExpression = Expression.New(ci);
}
}
if (createExpression == null)
{
createExpression = Expression.Default(typeof(T));
}
return(Expression.Lambda <DeserializeDelegate <T, TSymbol> >(createExpression, readerParameter).Compile());
}
var returnValue = Expression.Variable(typeof(T), "result");
MethodInfo nameSpanMethodInfo;
MethodInfo tryReadEndObjectMethodInfo;
MethodInfo beginObjectOrThrowMethodInfo;
if (typeof(TSymbol) == typeof(char))
{
nameSpanMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .ReadUtf16NameSpan));
tryReadEndObjectMethodInfo =
FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .TryReadUtf16IsEndObjectOrValueSeparator));
beginObjectOrThrowMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .ReadUtf16BeginObjectOrThrow));
}
else if (typeof(TSymbol) == typeof(byte))
{
nameSpanMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .ReadUtf8NameSpan));
tryReadEndObjectMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .TryReadUtf8IsEndObjectOrValueSeparator));
beginObjectOrThrowMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .ReadUtf8BeginObjectOrThrow));
}
else
{
throw new NotSupportedException();
}
// We need to decide during generation if we handle constructors or normal member assignment, the difference is done in the functor below
Func <JsonMemberInfo, Expression> matchExpressionFunctor;
Expression[] constructorParameterExpresssions = null;
if (objectDescription.Constructor != null)
{
// If we want to use the constructor we serialize into an array of variables internally and then create the object from that
var dict = objectDescription.ConstructorMapping;
constructorParameterExpresssions = new Expression[dict.Count];
foreach (var valueTuple in dict)
{
constructorParameterExpresssions[valueTuple.Value.Index] = Expression.Variable(valueTuple.Value.Type);
}
matchExpressionFunctor = memberInfo =>
{
var element = dict[memberInfo.MemberName];
var formatter = resolver.GetFormatter(memberInfo);
var formatterType = formatter.GetType();
var fieldInfo = formatterType.GetField("Default", BindingFlags.Static | BindingFlags.Public);
return(Expression.Assign(constructorParameterExpresssions[element.Index],
Expression.Call(Expression.Field(null, fieldInfo),
FindPublicInstanceMethod(formatterType, "Deserialize", readerParameter.Type.MakeByRefType()),
readerParameter)));
};
}
else
{
// The normal assign to member type
matchExpressionFunctor = memberInfo =>
{
var formatter = resolver.GetFormatter(memberInfo);
var formatterType = formatter.GetType();
var fieldInfo = formatterType.GetField("Default", BindingFlags.Static | BindingFlags.Public);
return(Expression.Assign(Expression.PropertyOrField(returnValue, memberInfo.MemberName),
Expression.Call(Expression.Field(null, fieldInfo),
FindPublicInstanceMethod(formatterType, "Deserialize", readerParameter.Type.MakeByRefType()),
readerParameter)));
};
}
var nameSpan = Expression.Variable(typeof(ReadOnlySpan <TSymbol>), "nameSpan");
var lengthParameter = Expression.Variable(typeof(int), "length");
var endOfBlockLabel = Expression.Label();
var nameSpanExpression = Expression.Call(readerParameter, nameSpanMethodInfo);
var assignNameSpan = Expression.Assign(nameSpan, nameSpanExpression);
var lengthExpression = Expression.Assign(lengthParameter, Expression.PropertyOrField(nameSpan, "Length"));
var byteNameSpan = Expression.Variable(typeof(ReadOnlySpan <byte>), "byteNameSpan");
var parameters = new List <ParameterExpression> {
nameSpan, lengthParameter
};
if (typeof(TSymbol) == typeof(char))
{
// For utf16 we need to convert the attribute name to bytes to feed it to the matching logic
Expression <Action> functor = () => MemoryMarshal.AsBytes(new ReadOnlySpan <char>());
var asBytesMethodInfo = (functor.Body as MethodCallExpression).Method;
nameSpanExpression = Expression.Call(null, asBytesMethodInfo, assignNameSpan);
assignNameSpan = Expression.Assign(byteNameSpan, nameSpanExpression);
parameters.Add(byteNameSpan);
}
else
{
byteNameSpan = nameSpan;
}
MethodInfo skipNextMethodInfo;
if (typeof(TSymbol) == typeof(char))
{
skipNextMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .SkipNextUtf16Segment));
}
else if (typeof(TSymbol) == typeof(byte))
{
skipNextMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .SkipNextUtf8Segment));
}
else
{
throw new NotSupportedException();
}
var expressions = new List <Expression>
{
assignNameSpan,
lengthExpression,
MemberComparisonBuilder.Build <TSymbol>(memberInfos, 0, lengthParameter, byteNameSpan, endOfBlockLabel, matchExpressionFunctor),
Expression.Call(readerParameter, skipNextMethodInfo),
Expression.Label(endOfBlockLabel),
};
var ifBlock = Expression.Block(parameters, expressions);
var countExpression = Expression.Parameter(typeof(int), "count");
var abortExpression = Expression.IsTrue(Expression.Call(readerParameter, tryReadEndObjectMethodInfo, countExpression));
var readBeginObject = Expression.Call(readerParameter, beginObjectOrThrowMethodInfo);
var loopAbort = Expression.Label(typeof(void));
var returnTarget = Expression.Label(returnValue.Type);
Expression block;
if (objectDescription.Constructor != null)
{
var blockParameters = new List <ParameterExpression> {
returnValue, countExpression
};
// ReSharper disable AssignNullToNotNullAttribute
blockParameters.AddRange(constructorParameterExpresssions.OfType <ParameterExpression>());
// ReSharper restore AssignNullToNotNullAttribute
block = Expression.Block(blockParameters, readBeginObject,
Expression.Loop(
Expression.IfThenElse(abortExpression, Expression.Break(loopAbort),
ifBlock), loopAbort
),
Expression.Assign(returnValue, Expression.New(objectDescription.Constructor, constructorParameterExpresssions)),
Expression.Label(returnTarget, returnValue)
);
}
else
{
block = Expression.Block(new[] { returnValue, countExpression }, readBeginObject,
Expression.Assign(returnValue, Expression.New(returnValue.Type)),
Expression.Loop(
Expression.IfThenElse(abortExpression, Expression.Break(loopAbort),
ifBlock), loopAbort
),
Expression.Label(returnTarget, returnValue)
);
}
var lambda = Expression.Lambda <DeserializeDelegate <T, TSymbol> >(block, readerParameter);
return(lambda.Compile());
}
/// <summary>
/// Not sure if it's useful to build something like the automaton from the compelxformatter here
/// </summary>
private static DeserializeDelegate BuildDeserializeDelegate()
{
var readerParameter = Expression.Parameter(typeof(JsonReader <TSymbol>).MakeByRefType(), "reader");
MethodInfo nameSpanMethodInfo;
if (typeof(TSymbol) == typeof(char))
{
nameSpanMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .ReadUtf16StringSpan));
}
else if (typeof(TSymbol) == typeof(byte))
{
nameSpanMethodInfo = FindPublicInstanceMethod(readerParameter.Type, nameof(JsonReader <TSymbol> .ReadUtf8StringSpan));
}
else
{
throw new NotSupportedException();
}
var returnValue = Expression.Variable(typeof(T), "returnValue");
var nameSpan = Expression.Variable(typeof(ReadOnlySpan <TSymbol>), "nameSpan");
var lengthParameter = Expression.Variable(typeof(int), "length");
var endOfBlockLabel = Expression.Label();
var nameSpanExpression = Expression.Call(readerParameter, nameSpanMethodInfo);
var assignNameSpan = Expression.Assign(nameSpan, nameSpanExpression);
var lengthExpression = Expression.Assign(lengthParameter, Expression.PropertyOrField(nameSpan, "Length"));
var byteNameSpan = Expression.Variable(typeof(ReadOnlySpan <byte>), "byteNameSpan");
var parameters = new List <ParameterExpression> {
nameSpan, lengthParameter, returnValue
};
if (typeof(TSymbol) == typeof(char))
{
Expression <Action> functor = () => MemoryMarshal.AsBytes(new ReadOnlySpan <char>());
var asBytesMethodInfo = (functor.Body as MethodCallExpression).Method;
nameSpanExpression = Expression.Call(null, asBytesMethodInfo, assignNameSpan);
assignNameSpan = Expression.Assign(byteNameSpan, nameSpanExpression);
parameters.Add(byteNameSpan);
}
else
{
byteNameSpan = nameSpan;
}
var memberInfos = new List <JsonMemberInfo>();
var dict = new Dictionary <string, T>();
foreach (var value in Enum.GetValues(typeof(T)))
{
var formattedValue = GetFormattedValue(value);
memberInfos.Add(new JsonMemberInfo(value.ToString(), typeof(T), null, formattedValue, false, true, false, null));
dict.Add(value.ToString(), (T)value);
}
Expression MatchExpressionFunctor(JsonMemberInfo memberInfo)
{
var enumValue = dict[memberInfo.MemberName];
return(Expression.Assign(returnValue, Expression.Constant(enumValue)));
}
var returnTarget = Expression.Label(returnValue.Type);
var returnLabel = Expression.Label(returnTarget, returnValue);
var expressions = new List <Expression>
{
assignNameSpan,
lengthExpression,
MemberComparisonBuilder.Build <TSymbol>(memberInfos, 0, lengthParameter, byteNameSpan, endOfBlockLabel, MatchExpressionFunctor),
Expression.Throw(Expression.Constant(new InvalidOperationException())),
Expression.Label(endOfBlockLabel),
returnLabel
};
var blockExpression = Expression.Block(parameters, expressions);
var lambdaExpression =
Expression.Lambda <DeserializeDelegate>(blockExpression, readerParameter);
return(lambdaExpression.Compile());
}
