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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "value.h"
namespace vespalib::eval {
/**
* Tagging interface used as return type from factories before
* downcasting to actual builder with specialized cell type.
**/
struct ValueBuilderBase {
virtual ~ValueBuilderBase() = default;
};
/**
* Interface used to build a value one dense subspace at a
* time. Enables decoupling of what the value should contain from how
* to store the value.
**/
template <typename T>
struct ValueBuilder : ValueBuilderBase {
// add a dense subspace for the given address (label for all
// mapped dimensions in canonical order). Note that previously
// returned subspaces will be invalidated when new subspaces are
// added. Also note that adding the same subspace multiple times
// is not allowed.
virtual ArrayRef<T> add_subspace(ConstArrayRef<vespalib::stringref> addr) = 0;
// add a dense subspace for the given address where labels are
// specified by shared string repo ids. Note that the caller is
// responsible for making sure the ids are valid 'long enough'.
virtual ArrayRef<T> add_subspace(ConstArrayRef<string_id> addr) = 0;
// convenience function to add a subspace with an empty address
ArrayRef<T> add_subspace() { return add_subspace(ConstArrayRef<string_id>()); }
// Given the ownership of the builder itself, produce the newly
// created value. This means that builders can only be used once,
// it also means values can build themselves.
virtual std::unique_ptr<Value> build(std::unique_ptr<ValueBuilder> self) = 0;
};
/**
* Factory able to create appropriate value builders. We do not really
* care about the full mathematical type here, but it needs to be
* passed since it is exposed in the value api. The expected number of
* subspaces is also passed since it enables the builder to pre-size
* internal structures appropriately. Note that since we are not able
* to have virtual templated functions we need to cast the created
* builder. With interoperability between all values.
**/
struct ValueBuilderFactory {
private:
template <typename T>
std::unique_ptr<ValueBuilder<T>> create_value_builder(const ValueType &type, bool transient,
size_t num_mapped_dims_in, size_t subspace_size_in, size_t expected_subspaces) const
{
assert(check_cell_type<T>(type.cell_type()));
auto base = create_value_builder_base(type, transient, num_mapped_dims_in, subspace_size_in, expected_subspaces);
auto *builder = static_cast<ValueBuilder<T>*>(base.get());
base.release();
return std::unique_ptr<ValueBuilder<T>>(builder);
}
public:
template <typename T>
std::unique_ptr<ValueBuilder<T>> create_value_builder(const ValueType &type,
size_t num_mapped_dims_in, size_t subspace_size_in, size_t expected_subspaces) const
{
return create_value_builder<T>(type, false, num_mapped_dims_in, subspace_size_in, expected_subspaces);
}
template <typename T>
std::unique_ptr<ValueBuilder<T>> create_transient_value_builder(const ValueType &type,
size_t num_mapped_dims_in, size_t subspace_size_in, size_t expected_subspaces) const
{
return create_value_builder<T>(type, true, num_mapped_dims_in, subspace_size_in, expected_subspaces);
}
template <typename T>
std::unique_ptr<ValueBuilder<T>> create_value_builder(const ValueType &type) const
{
return create_value_builder<T>(type, false, type.count_mapped_dimensions(), type.dense_subspace_size(), 1);
}
std::unique_ptr<Value> copy(const Value &value) const;
virtual ~ValueBuilderFactory() = default;
protected:
virtual std::unique_ptr<ValueBuilderBase> create_value_builder_base(const ValueType &type, bool transient,
size_t num_mapped_dims_in, size_t subspace_size_in, size_t expected_subspaces) const = 0;
};
}
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