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24 lines
545 B
C++
24 lines
545 B
C++
#pragma once
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#include "store-api.hh"
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namespace nix {
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/**
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* Helper to try downcasting a Store with a nice method if it fails.
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*
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* This is basically an alternative to the user-facing part of
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* Store::unsupported that allows us to still have a nice message but
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* better interface design.
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*/
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template<typename T>
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T & require(Store & store)
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{
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auto * castedStore = dynamic_cast<T *>(&store);
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if (!castedStore)
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throw UsageError("%s not supported by store '%s'", T::operationName, store.getUri());
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return *castedStore;
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}
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}
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