c10c61449f
Also, move a few free-standing functions into StoreAPI and Derivation. Also, introduce a non-nullable smart pointer, ref<T>, which is just a wrapper around std::shared_ptr ensuring that the pointer is never null. (For reference-counted values, this is better than passing a "T&", because the latter doesn't maintain the refcount. Usually, the caller will have a shared_ptr keeping the value alive, but that's not always the case, e.g., when passing a reference to a std::thread via std::bind.)
166 lines
3.3 KiB
C++
166 lines
3.3 KiB
C++
#pragma once
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#include "config.h"
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#include <string>
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#include <list>
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#include <set>
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#include <memory>
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#include <boost/format.hpp>
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/* Before 4.7, gcc's std::exception uses empty throw() specifiers for
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* its (virtual) destructor and what() in c++11 mode, in violation of spec
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*/
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#ifdef __GNUC__
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#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
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#define EXCEPTION_NEEDS_THROW_SPEC
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#endif
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#endif
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namespace nix {
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/* Inherit some names from other namespaces for convenience. */
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using std::string;
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using std::list;
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using std::set;
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using std::vector;
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using boost::format;
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struct FormatOrString
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{
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string s;
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FormatOrString(const string & s) : s(s) { };
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FormatOrString(const format & f) : s(f.str()) { };
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FormatOrString(const char * s) : s(s) { };
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};
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/* BaseError should generally not be caught, as it has Interrupted as
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a subclass. Catch Error instead. */
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class BaseError : public std::exception
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{
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protected:
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string prefix_; // used for location traces etc.
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string err;
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public:
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unsigned int status; // exit status
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BaseError(const FormatOrString & fs, unsigned int status = 1);
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#ifdef EXCEPTION_NEEDS_THROW_SPEC
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~BaseError() throw () { };
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const char * what() const throw () { return err.c_str(); }
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#else
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const char * what() const noexcept { return err.c_str(); }
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#endif
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const string & msg() const { return err; }
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const string & prefix() const { return prefix_; }
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BaseError & addPrefix(const FormatOrString & fs);
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};
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#define MakeError(newClass, superClass) \
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class newClass : public superClass \
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{ \
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public: \
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newClass(const FormatOrString & fs, unsigned int status = 1) : superClass(fs, status) { }; \
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};
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MakeError(Error, BaseError)
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class SysError : public Error
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{
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public:
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int errNo;
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SysError(const FormatOrString & fs);
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};
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typedef list<string> Strings;
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typedef set<string> StringSet;
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/* Paths are just strings. */
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typedef string Path;
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typedef list<Path> Paths;
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typedef set<Path> PathSet;
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typedef enum {
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lvlError = 0,
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lvlInfo,
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lvlTalkative,
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lvlChatty,
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lvlDebug,
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lvlVomit
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} Verbosity;
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/* A simple non-nullable reference-counted pointer. Actually a wrapper
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around std::shared_ptr that prevents non-null constructions. */
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template<typename T>
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class ref
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{
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private:
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std::shared_ptr<T> p;
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public:
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ref<T>(const ref<T> & r)
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: p(r.p)
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{ }
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explicit ref<T>(const std::shared_ptr<T> & p)
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: p(p)
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{
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if (!p)
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throw std::invalid_argument("null pointer cast to ref");
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}
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T* operator ->() const
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{
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return &*p;
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}
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T& operator *() const
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{
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return *p;
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}
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operator std::shared_ptr<T> ()
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{
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return p;
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}
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private:
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template<typename T2, typename... Args>
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friend ref<T2>
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make_ref(Args&&... args);
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template<typename T2, typename T3, typename... Args>
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friend ref<T2>
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make_ref(Args&&... args);
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};
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template<typename T, typename... Args>
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inline ref<T>
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make_ref(Args&&... args)
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{
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auto p = std::make_shared<T>(std::forward<Args>(args)...);
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return ref<T>(p);
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}
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template<typename T, typename T2, typename... Args>
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inline ref<T>
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make_ref(Args&&... args)
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{
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auto p = std::make_shared<T2>(std::forward<Args>(args)...);
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return ref<T>(p);
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}
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}
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