/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="NullSchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// is a <see cref="NullSchema" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is NullSchema)
{
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
return(JsonDeserializerBuilderCaseResult.FromExpression(
Expression.Block(
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.Null)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.Null })))),
Expression.Default(type))));
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonNullDeserializerBuilderCase)} can only be applied to {nameof(NullSchema)}s.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="TimestampLogicalType" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// has a <see cref="TimestampLogicalType" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <exception cref="UnsupportedSchemaException">
/// Thrown when <paramref name="schema" /> is not a <see cref="LongSchema" /> or when
/// <paramref name="schema" /> does not have a <see cref="MicrosecondTimestampLogicalType" />
/// or a <see cref="MillisecondTimestampLogicalType" />.
/// </exception>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <see cref="DateTime" /> cannot be converted to <paramref name="type" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema.LogicalType is TimestampLogicalType)
{
if (schema is not LongSchema)
{
throw new UnsupportedSchemaException(schema);
}
Expression epoch = Expression.Constant(Epoch);
Expression factor;
if (schema.LogicalType is MicrosecondTimestampLogicalType)
{
factor = Expression.Constant(TimeSpan.TicksPerMillisecond / 1000);
}
else if (schema.LogicalType is MillisecondTimestampLogicalType)
{
factor = Expression.Constant(TimeSpan.TicksPerMillisecond);
}
else
{
throw new UnsupportedSchemaException(schema);
}
var getInt64 = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetInt64), Type.EmptyTypes);
Expression expression = Expression.Call(context.Reader, getInt64);
var addTicks = typeof(DateTime)
.GetMethod(nameof(DateTime.AddTicks));
try
{
// return Epoch.AddTicks(value * factor);
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(
Expression.Call(epoch, addTicks, Expression.Multiply(expression, factor)),
type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {schema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonTimestampDeserializerBuilderCase)} can only be applied schemas with a {nameof(TimestampLogicalType)}.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="BytesSchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// is a <see cref="BytesSchema" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <see cref="T:System.Byte[]" /> cannot be converted to <paramref name="type" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is BytesSchema bytesSchema)
{
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
var getString = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetString), Type.EmptyTypes);
var getBytes = typeof(Encoding)
.GetMethod(nameof(Encoding.GetBytes), new[] { typeof(string) });
try
{
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(
Expression.Block(
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.String)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.String })))),
Expression.Call(
Expression.Constant(JsonEncoding.Bytes),
getBytes,
Expression.Call(context.Reader, getString))),
type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {bytesSchema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonBytesDeserializerBuilderCase)} can only be applied to {nameof(BytesSchema)}s.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="LongSchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// is a <see cref="LongSchema" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <see cref="long" /> cannot be converted to <paramref name="type" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is LongSchema longSchema)
{
var getInt64 = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetInt64), Type.EmptyTypes);
try
{
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(Expression.Call(context.Reader, getInt64), type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {longSchema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonLongDeserializerBuilderCase)} can only be applied to {nameof(LongSchema)}s.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="DecimalLogicalType" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// has a <see cref="DecimalLogicalType" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <exception cref="UnsupportedSchemaException">
/// Thrown when <paramref name="schema" /> is not a <see cref="BytesSchema" /> or a
/// <see cref="FixedSchema "/>.
/// </exception>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <see cref="decimal" /> cannot be converted to <paramref name="type" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema.LogicalType is DecimalLogicalType decimalLogicalType)
{
var precision = decimalLogicalType.Precision;
var scale = decimalLogicalType.Scale;
var bytes = Expression.Variable(typeof(byte[]));
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
var getString = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetString), Type.EmptyTypes);
var getBytes = typeof(Encoding)
.GetMethod(nameof(Encoding.GetBytes), new[] { typeof(string) });
var getUnexpectedSizeException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedSizeException));
Expression expression;
if (schema is BytesSchema)
{
expression = Expression.Block(
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.String)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.String })))),
Expression.Assign(
bytes,
Expression.Call(
Expression.Constant(JsonEncoding.Bytes),
getBytes,
Expression.Call(context.Reader, getString))),
bytes);
}
else if (schema is FixedSchema fixedSchema)
{
expression = Expression.Block(
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.String)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.String })))),
Expression.Assign(
bytes,
Expression.Call(
Expression.Constant(JsonEncoding.Bytes),
getBytes,
Expression.Call(context.Reader, getString))),
Expression.IfThen(
Expression.NotEqual(
Expression.ArrayLength(bytes),
Expression.Constant(fixedSchema.Size)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedSizeException,
context.Reader,
Expression.Constant(fixedSchema.Size),
Expression.ArrayLength(bytes)))),
bytes);
}
else
{
throw new UnsupportedSchemaException(schema);
}
// declare variables for in-place transformation:
var remainder = Expression.Variable(typeof(BigInteger));
var divide = typeof(BigInteger)
.GetMethod(nameof(BigInteger.DivRem), new[] { typeof(BigInteger), typeof(BigInteger), typeof(BigInteger).MakeByRefType() });
var integerConstructor = typeof(BigInteger)
.GetConstructor(new[] { typeof(byte[]) });
var reverse = typeof(Array)
.GetMethod(nameof(Array.Reverse), new[] { typeof(Array) });
// var bytes = ...;
//
// // BigInteger is little-endian, so reverse:
// Array.Reverse(bytes);
//
// var whole = BigInteger.DivRem(new BigInteger(bytes), BigInteger.Pow(10, scale), out var remainder);
// var fraction = (decimal)remainder / (decimal)Math.Pow(10, scale);
//
// return whole + fraction;
expression = Expression.Block(
new[] { bytes, remainder },
Expression.Assign(bytes, expression),
Expression.Call(null, reverse, bytes),
Expression.Add(
Expression.ConvertChecked(
Expression.Call(
null,
divide,
Expression.New(integerConstructor, bytes),
Expression.Constant(BigInteger.Pow(10, scale)),
remainder),
typeof(decimal)),
Expression.Divide(
Expression.ConvertChecked(remainder, typeof(decimal)),
Expression.Constant((decimal)Math.Pow(10, scale)))));
try
{
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(expression, type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {schema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonDecimalDeserializerBuilderCase)} can only be applied schemas with a {nameof(DecimalLogicalType)}.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for an <see cref="ArraySchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="type" />
/// is an enumerable type and <paramref name="schema" /> is an <see cref="ArraySchema" />;
/// an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" /> otherwise.
/// </returns>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <paramref name="type" /> is not assignable from any supported array or
/// collection <see cref="Type" /> and does not have a constructor that can be used to
/// instantiate it.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is ArraySchema arraySchema)
{
var enumerableType = GetEnumerableType(type);
if (enumerableType is not null || type == typeof(object))
{
// support dynamic mapping:
var itemType = enumerableType ?? typeof(object);
var instantiateCollection = BuildIntermediateCollection(type, itemType);
var readItem = DeserializerBuilder
.BuildExpression(itemType, arraySchema.Item, context);
var collection = Expression.Parameter(instantiateCollection.Type);
var loop = Expression.Label();
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
var read = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.Read), Type.EmptyTypes);
var add = collection.Type.GetMethod("Add", new[] { readItem.Type });
Expression expression = Expression.Block(
new[] { collection },
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.StartArray)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.StartArray })))),
Expression.Assign(collection, instantiateCollection),
Expression.Loop(
Expression.Block(
Expression.Call(context.Reader, read),
Expression.IfThen(
Expression.Equal(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.EndArray)),
Expression.Break(loop)),
Expression.Call(collection, add, readItem)),
loop),
collection);
if (!type.IsAssignableFrom(expression.Type) && GetCollectionConstructor(type) is ConstructorInfo constructor)
{
expression = Expression.New(constructor, expression);
}
try
{
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(expression, type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {arraySchema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedTypeException(type, $"{nameof(JsonArrayDeserializerBuilderCase)} can only be applied to enumerable types.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="DurationLogicalType" />.
/// </summary>
/// <returns>
/// A successful result if <paramref name="type" /> the schema’s logical type is a
/// <see cref="DurationLogicalType" />; an unsuccessful result otherwise.
/// </returns>
/// <exception cref="UnsupportedSchemaException">
/// Thrown when the schema is not a <see cref="FixedSchema" /> with size 12 and logical
/// type <see cref="DurationLogicalType" />.
/// </exception>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <see cref="TimeSpan" /> cannot be converted to <paramref name="type" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema.LogicalType is DurationLogicalType)
{
if (!(schema is FixedSchema fixedSchema && fixedSchema.Size == 12))
{
throw new UnsupportedSchemaException(schema);
}
var bytes = Expression.Parameter(typeof(byte[]));
var copy = typeof(Array)
.GetMethod(nameof(Array.Copy), new[] { typeof(Array), typeof(int), typeof(Array), typeof(int), typeof(int) });
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
var getString = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetString), Type.EmptyTypes);
var getBytes = typeof(Encoding)
.GetMethod(nameof(Encoding.GetBytes), new[] { typeof(string) });
var getUnexpectedSizeException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedSizeException));
var reverse = typeof(Array)
.GetMethod(nameof(Array.Reverse), new[] { typeof(Array) });
var toUInt32 = typeof(BitConverter)
.GetMethod(nameof(BitConverter.ToUInt32), new[] { typeof(byte[]), typeof(int) });
Expression Read(Expression offset)
{
var component = Expression.Variable(typeof(byte[]));
var expressions = new List <Expression>
{
Expression.Assign(
component,
Expression.NewArrayBounds(typeof(byte), Expression.Constant(4))),
Expression.Call(null, copy, bytes, offset, component, Expression.Constant(0), Expression.ArrayLength(component)),
};
if (!BitConverter.IsLittleEndian)
{
expressions.Add(Expression.Call(null, reverse, Expression.Convert(component, typeof(Array))));
}
expressions.Add(component);
return(Expression.ConvertChecked(
Expression.Call(
null,
toUInt32,
Expression.Block(
new[] { component },
expressions),
Expression.Constant(0)),
typeof(long)));
}
var exceptionConstructor = typeof(OverflowException)
.GetConstructor(new[] { typeof(string) });
var timeSpanConstructor = typeof(TimeSpan)
.GetConstructor(new[] { typeof(long) });
try
{
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(
Expression.Block(
new[] { bytes },
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.String)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.String })))),
Expression.Assign(
bytes,
Expression.Call(
Expression.Constant(JsonEncoding.Bytes),
getBytes,
Expression.Call(context.Reader, getString))),
Expression.IfThen(
Expression.NotEqual(
Expression.ArrayLength(bytes),
Expression.Constant(fixedSchema.Size)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedSizeException,
context.Reader,
Expression.Constant(fixedSchema.Size),
Expression.ArrayLength(bytes)))),
Expression.IfThen(
Expression.NotEqual(Read(Expression.Constant(0)), Expression.Constant(0L)),
Expression.Throw(
Expression.New(
exceptionConstructor,
Expression.Constant("Durations containing months cannot be accurately deserialized to a TimeSpan.")))),
Expression.New(
timeSpanConstructor,
Expression.AddChecked(
Expression.MultiplyChecked(Read(Expression.Constant(4)), Expression.Constant(TimeSpan.TicksPerDay)),
Expression.MultiplyChecked(Read(Expression.Constant(8)), Expression.Constant(TimeSpan.TicksPerMillisecond))))),
type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {schema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonDurationDeserializerBuilderCase)} can only be applied schemas with a {nameof(DurationLogicalType)}.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="MapSchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="type" />
/// is a dictionary type and <paramref name="schema" /> is a <see cref="MapSchema" />; an
/// unsuccessful <see cref="JsonDeserializerBuilderCaseResult" /> otherwise.
/// </returns>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <paramref name="type" /> is not assignable from any supported dictionary
/// <see cref="Type" /> and does not have a constructor that can be used to instantiate it.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is MapSchema mapSchema)
{
var dictionaryTypes = GetDictionaryTypes(type);
if (dictionaryTypes is not null || type == typeof(object))
{
// support dynamic mapping:
var keyType = dictionaryTypes?.Key ?? typeof(string);
var valueType = dictionaryTypes?.Value ?? typeof(object);
var instantiateDictionary = BuildIntermediateDictionary(type, keyType, valueType);
var readKey = DeserializerBuilder
.BuildExpression(keyType, new StringSchema(), context);
var readValue = DeserializerBuilder
.BuildExpression(valueType, mapSchema.Value, context);
var dictionary = Expression.Parameter(instantiateDictionary.Type);
var key = Expression.Parameter(readKey.Type);
var loop = Expression.Label();
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
var read = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.Read), Type.EmptyTypes);
var add = dictionary.Type.GetMethod("Add", new[] { readKey.Type, readValue.Type });
Expression expression = Expression.Block(
new[] { dictionary },
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.StartObject)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.StartObject })))),
Expression.Assign(dictionary, instantiateDictionary),
Expression.Loop(
Expression.Block(
new[] { key },
Expression.Call(context.Reader, read),
Expression.IfThen(
Expression.Equal(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.EndObject)),
Expression.Break(loop)),
Expression.Assign(key, readKey),
Expression.Call(context.Reader, read),
Expression.Call(dictionary, add, key, readValue)),
loop),
dictionary);
if (!type.IsAssignableFrom(expression.Type) && GetDictionaryConstructor(type) is ConstructorInfo constructor)
{
expression = Expression.New(constructor, expression);
}
try
{
return(JsonDeserializerBuilderCaseResult.FromExpression(
BuildConversion(expression, type)));
}
catch (InvalidOperationException exception)
{
throw new UnsupportedTypeException(type, $"Failed to map {mapSchema} to {type}.", exception);
}
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedTypeException(type, $"{nameof(JsonMapDeserializerBuilderCase)} can only be applied to dictionary types.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for an <see cref="EnumSchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// is an <see cref="EnumSchema" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <paramref name="type" /> is an enum type without a matching member for each
/// symbol in <paramref name="schema" /> or when <see cref="string" /> cannot be converted
/// to <paramref name="type" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is EnumSchema enumSchema)
{
var getString = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetString), Type.EmptyTypes);
Expression expression = Expression.Call(context.Reader, getString);
var underlying = Nullable.GetUnderlyingType(type) ?? type;
// enum fields will always be public static, so no need to expose binding flags:
var fields = underlying.GetFields(BindingFlags.Public | BindingFlags.Static);
// find a match for each enum in the schema:
var cases = underlying.IsEnum
? enumSchema.Symbols
.Select(symbol =>
{
var match = fields.SingleOrDefault(field => IsMatch(symbol, field));
if (enumSchema.Default != null)
{
match ??= fields.SingleOrDefault(field => IsMatch(enumSchema.Default, field));
}
if (match == null)
{
throw new UnsupportedTypeException(type, $"{type} has no value that matches {symbol} and no default value is defined.");
}
return(Expression.SwitchCase(
BuildConversion(Expression.Constant(Enum.Parse(underlying, match.Name)), type),
Expression.Constant(symbol)));
})
: enumSchema.Symbols
.Select(symbol =>
{
return(Expression.SwitchCase(
BuildConversion(Expression.Constant(symbol), type),
Expression.Constant(symbol)));
});
var position = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenStartIndex))
.GetGetMethod();
var exceptionConstructor = typeof(InvalidEncodingException)
.GetConstructor(new[] { typeof(long), typeof(string), typeof(Exception) });
// generate a switch on the symbol:
return(JsonDeserializerBuilderCaseResult.FromExpression(
Expression.Switch(
expression,
Expression.Throw(
Expression.New(
exceptionConstructor,
Expression.Property(context.Reader, position),
Expression.Constant($"Invalid enum symbol."),
Expression.Constant(null, typeof(Exception))),
type),
cases.ToArray())));
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonEnumDeserializerBuilderCase)} can only be applied to {nameof(EnumSchema)}s.")));
}
}
/// <summary>
/// Builds a <see cref="JsonDeserializer{T}" /> for a <see cref="UnionSchema" />.
/// </summary>
/// <returns>
/// A successful <see cref="JsonDeserializerBuilderCaseResult" /> if <paramref name="schema" />
/// is a <see cref="UnionSchema" />; an unsuccessful <see cref="JsonDeserializerBuilderCaseResult" />
/// otherwise.
/// </returns>
/// <exception cref="UnsupportedSchemaException">
/// Thrown when <paramref name="schema" /> has no <see cref="UnionSchema.Schemas" />.
/// </exception>
/// <exception cref="UnsupportedTypeException">
/// Thrown when <paramref name="type" /> cannot be mapped to each <see cref="Schema" /> in
/// <paramref name="schema" />.
/// </exception>
/// <inheritdoc />
public virtual JsonDeserializerBuilderCaseResult BuildExpression(Type type, Schema schema, JsonDeserializerBuilderContext context)
{
if (schema is UnionSchema unionSchema)
{
if (unionSchema.Schemas.Count < 1)
{
throw new UnsupportedSchemaException(schema, "A deserializer cannot be built for an empty union.");
}
var tokenType = typeof(Utf8JsonReader)
.GetProperty(nameof(Utf8JsonReader.TokenType));
var getUnexpectedTokenException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnexpectedTokenException));
var read = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.Read), Type.EmptyTypes);
var getString = typeof(Utf8JsonReader)
.GetMethod(nameof(Utf8JsonReader.GetString), Type.EmptyTypes);
var getUnknownUnionMemberException = typeof(JsonExceptionHelper)
.GetMethod(nameof(JsonExceptionHelper.GetUnknownUnionMemberException));
var schemas = unionSchema.Schemas.ToList();
var candidates = schemas.Where(s => s is not NullSchema).ToList();
var @null = schemas.Find(s => s is NullSchema);
var cases = candidates.Select(child =>
{
var selected = SelectType(type, child);
return(Expression.SwitchCase(
BuildConversion(
Expression.Block(
Expression.Call(context.Reader, read),
DeserializerBuilder.BuildExpression(selected, child, context)),
type),
Expression.Constant(GetSchemaName(child))));
}).ToArray();
var value = Expression.Parameter(type);
Expression expression = Expression.Block(
new[] { value },
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.StartObject)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.StartObject })))),
Expression.Call(context.Reader, read),
Expression.Assign(
value,
Expression.Switch(
Expression.Call(context.Reader, getString),
Expression.Throw(
Expression.Call(
null,
getUnknownUnionMemberException,
context.Reader),
type),
cases)),
Expression.Call(context.Reader, read),
Expression.IfThen(
Expression.NotEqual(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.EndObject)),
Expression.Throw(
Expression.Call(
null,
getUnexpectedTokenException,
context.Reader,
Expression.Constant(new[] { JsonTokenType.EndObject })))),
value);
if (@null != null)
{
var selected = SelectType(type, @null);
var underlying = Nullable.GetUnderlyingType(selected);
if (selected.IsValueType && underlying == null)
{
throw new UnsupportedTypeException(type, $"A deserializer for a union containing {typeof(NullSchema)} cannot be built for {selected}.");
}
expression = Expression.Condition(
Expression.Equal(
Expression.Property(context.Reader, tokenType),
Expression.Constant(JsonTokenType.Null)),
BuildConversion(
DeserializerBuilder.BuildExpression(selected, @null, context),
type),
expression);
}
return(JsonDeserializerBuilderCaseResult.FromExpression(expression));
}
else
{
return(JsonDeserializerBuilderCaseResult.FromException(new UnsupportedSchemaException(schema, $"{nameof(JsonUnionDeserializerBuilderCase)} can only be applied to {nameof(UnionSchema)}s.")));
}
}