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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <memory>
#include <vespa/eval/eval/value.h>
#include <vespa/eval/eval/value_type.h>
namespace vespalib {
namespace eval {
/**
* Abstract wrapper of a typed constant value. The lifetime of the
* wrapper controls the lifetime of the underlying type and value as
* well.
**/
struct ConstantValue {
virtual const ValueType &type() const = 0;
virtual const Value &value() const = 0;
using UP = std::unique_ptr<ConstantValue>;
virtual ~ConstantValue() {}
};
class SimpleConstantValue : public ConstantValue {
private:
const Value::UP _value;
public:
SimpleConstantValue(Value::UP value) : _value(std::move(value)) {}
const ValueType &type() const override { return _value->type(); }
const Value &value() const override { return *_value; }
};
class BadConstantValue : public ConstantValue {
private:
const ValueType _type;
public:
BadConstantValue() : _type(ValueType::error_type()) {}
const ValueType &type() const override { return _type; }
const Value &value() const override { abort(); }
};
/**
* An abstract factory of constant values. The typical use-case for
* this will be to load constant values from file with a cache on top
* to share constants among users.
**/
struct ConstantValueFactory {
virtual ConstantValue::UP create(const vespalib::string &path, const vespalib::string &type) const = 0;
virtual ~ConstantValueFactory() {}
};
} // namespace vespalib::eval
} // namespace vespalib
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