Expression Struct(IParser parser, RuntimeSchema schema, bool isBase)
{
var metadata = schema.HasValue ? Expression.Constant(schema.StructDef.metadata) : noMetadata;
var baseSchema = schema.HasBase ? schema.GetBaseSchema() : RuntimeSchema.Empty;
return(parser.Apply(new Transform(
Begin: () => isBase ? writer.WriteBaseBegin(metadata) : writer.WriteStructBegin(metadata),
End: () => isBase ? writer.WriteBaseEnd() : writer.WriteStructEnd(),
Fields: schema.HasValue ?
from field in schema.StructDef.fields
select new Field(
Id: field.id,
Value: (fieldParser, fieldType) =>
Expression.Block(
writer.WriteFieldBegin(fieldType, field.id, field.metadata),
Value(fieldParser, fieldType, schema.GetFieldSchema(field)),
writer.WriteFieldEnd()),
Omitted: () => writer.WriteFieldOmitted(field.type.id, field.id, field.metadata)) :
null,
UnknownField: (fieldParser, fieldType, fieldId) =>
Expression.Block(
writer.WriteFieldBegin(fieldType, fieldId, noMetadata),
Value(fieldParser, fieldType),
writer.WriteFieldEnd()),
Base: baseParser =>
baseSchema.HasValue ? Struct(baseParser, baseSchema, isBase: true) : Expression.Empty(),
UnknownEnd: () => writer.WriteBaseEnd())));
}
public Expression Apply(ITransform transform)
{
Debug.Assert(schema.IsStruct);
var body = new List <Expression>
{
transform.Begin
};
if (schema.HasBase)
{
body.Add(transform.Base(new UntaggedParser <R>(this, schema.GetBaseSchema())));
}
// Performs left outer join of schema fields with transform fields.
// The result contains entry for each schema field. For fields not handled
// by the transform default to Skip.
body.AddRange(
from fieldDef in schema.StructDef.fields
join transfromField in transform.Fields on fieldDef.id equals transfromField.Id into fields
from knownField in fields.DefaultIfEmpty()
select Field(transform, fieldDef, knownField));
body.Add(transform.End);
return(Expression.Block(body));
}
public Expression Apply(ITransform transform)
{
pairs.Add(new TransformSchemaPair(transform, schema));
if (schema.HasBase)
{
schema = schema.GetBaseSchema();
transform.Base(this);
}
return(Expression.Empty());
}