private Expression ProcessFieldElement(
Expression state,
ParameterExpression requiredFields,
IEnumerable <TransformSchemaPair> transforms)
{
var requiredIndex = 0;
// start from the expression to handle unknown element (will be executed at the end of the if/else chain)
Expression body = Expression.Block(
Reader.Skip(),
Expression.Assign(state, Expression.Constant(State.InsideStructElement)));
// if there are transform/schema pairs for base structs, process their fields as well into the expression
foreach (var pair in transforms)
{
var index = 0;
var structDef = pair.Schema.StructDef;
foreach (var field in pair.Transform.Fields)
{
var fieldDef = structDef.fields[index++];
Debug.Assert(field.Id == fieldDef.id);
var parser = new SimpleXmlParser <R>(this, pair.Schema.GetFieldSchema(fieldDef));
// process field - and set the state to expect to see the field element's end
var handleField = new List <Expression>
{
field.Value(parser, Expression.Constant(fieldDef.type.id)),
Expression.Assign(state, Expression.Constant(State.AtFieldEndElement))
};
if (fieldDef.metadata.modifier == Modifier.Required)
{
handleField.Add(RequiredFields.Mark(requiredFields, requiredIndex++));
}
body = Expression.IfThenElse(
NodeNameEquals(fieldDef.metadata.name, structDef.metadata.GetXmlNamespace()),
Expression.Block(handleField),
body);
}
}
return(body);
}
Expression ProcessField(ParameterExpression requiredFields, IEnumerable <TransformSchemaPair> transforms)
{
// unknown fields are skipped (read past the unknown PropertyName then skip the value)
Expression body = Expression.Block(
Reader.Read(),
SkipValue());
var requiredIndex = 0;
foreach (var pair in transforms)
{
var currentSchema = pair.Schema;
var currentTransform = pair.Transform;
var structDef = currentSchema.StructDef;
var index = 0;
foreach (var field in currentTransform.Fields)
{
var fieldDef = structDef.fields[index++];
Debug.Assert(field.Id == fieldDef.id);
var parser = new SimpleJsonParser <R>(this, currentSchema.GetFieldSchema(fieldDef));
// chain ifs on field name to handle the value on the right field handler
var handleField = field.Value(parser, Expression.Constant(fieldDef.type.id));
if (fieldDef.metadata.modifier == Modifier.Required)
{
handleField = Expression.Block(RequiredFields.Mark(requiredFields, requiredIndex++), handleField);
}
string name;
body = Expression.IfThenElse(
PropertyNameEquals(fieldDef.metadata.attributes.TryGetValue(
SimpleJsonWriter.NameAttribute, out name) ? name : fieldDef.metadata.name),
Expression.Block(Read(), handleField),
body);
}
}
return(body);
}