eldritch horrorsandjade
b0d7a81613
clangd broke because it can't look through symlinks. compile_commands manipulation does not fix it, clangd configuration does not fix it, a vfs overlay does not fix it, and while a combination of those can fix it with a bind mount in place that's just too cursed to even consider clangd bug: https://github.com/llvm/llvm-project/issues/116877 Change-Id: I8e3e8489548eb3a7aa65ac9d12a5ec8abf814aec
70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
#pragma once
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/// @file String view that can be either owned or borrowed.
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#include <variant>
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#include <string>
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#include <string_view>
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/**
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* This wants to be a little bit like rust's Cow type.
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* Some parts of the evaluator benefit greatly from being able to reuse
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* existing allocations for strings, but have to be able to also use
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* newly allocated storage for values.
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*
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* We do not define implicit conversions, even with ref qualifiers,
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* since those can easily become ambiguous to the reader and can degrade
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* into copying behaviour we want to avoid.
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*/
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class BackedStringView {
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private:
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std::variant<std::string, std::string_view> data;
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/**
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* Needed to introduce a temporary since operator-> must return
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* a pointer. Without this we'd need to store the view object
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* even when we already own a string.
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*/
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class Ptr {
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private:
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std::string_view view;
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public:
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Ptr(std::string_view view): view(view) {}
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const std::string_view * operator->() const { return &view; }
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};
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public:
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BackedStringView(std::string && s): data(std::move(s)) {}
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BackedStringView(std::string_view sv): data(sv) {}
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template<size_t N>
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BackedStringView(const char (& lit)[N]): data(std::string_view(lit)) {}
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BackedStringView(const BackedStringView &) = delete;
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BackedStringView & operator=(const BackedStringView &) = delete;
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/**
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* We only want move operations defined since the sole purpose of
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* this type is to avoid copies.
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*/
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BackedStringView(BackedStringView && other) = default;
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BackedStringView & operator=(BackedStringView && other) = default;
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bool isOwned() const
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{
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return std::holds_alternative<std::string>(data);
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}
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std::string toOwned() &&
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{
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return isOwned()
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? std::move(std::get<std::string>(data))
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: std::string(std::get<std::string_view>(data));
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}
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std::string_view operator*() const
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{
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return isOwned()
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? std::get<std::string>(data)
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: std::get<std::string_view>(data);
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}
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Ptr operator->() const { return Ptr(**this); }
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};
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