462421d345
This provides a pluggable mechanism for defining new fetchers. It adds
a builtin function 'fetchTree' that generalizes existing fetchers like
'fetchGit', 'fetchMercurial' and 'fetchTarball'. 'fetchTree' takes a
set of attributes, e.g.
fetchTree {
type = "git";
url = "https://example.org/repo.git";
ref = "some-branch";
rev = "abcdef...";
}
The existing fetchers are just wrappers around this. Note that the
input attributes to fetchTree are the same as flake input
specifications and flake lock file entries.
All fetchers share a common cache stored in
~/.cache/nix/fetcher-cache-v1.sqlite. This replaces the ad hoc caching
mechanisms in fetchGit and download.cc (e.g. ~/.cache/nix/{tarballs,git-revs*}).
This also adds support for Git worktrees (c169ea5904).
169 lines
3.6 KiB
C++
169 lines
3.6 KiB
C++
#pragma once
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#include "ref.hh"
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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 <map>
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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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/* A variadic template that does nothing. Useful to call a function
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for all variadic arguments but ignoring the result. */
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struct nop { template<typename... T> nop(T...) {} };
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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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/* A helper for formatting strings. ‘fmt(format, a_0, ..., a_n)’ is
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equivalent to ‘boost::format(format) % a_0 % ... %
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... a_n’. However, ‘fmt(s)’ is equivalent to ‘s’ (so no %-expansion
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takes place). */
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inline void formatHelper(boost::format & f)
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{
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}
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template<typename T, typename... Args>
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inline void formatHelper(boost::format & f, const T & x, const Args & ... args)
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{
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formatHelper(f % x, args...);
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}
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inline std::string fmt(const std::string & s)
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{
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return s;
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}
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inline std::string fmt(const char * s)
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{
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return s;
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}
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inline std::string fmt(const FormatOrString & fs)
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{
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return fs.s;
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}
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template<typename... Args>
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inline std::string fmt(const std::string & fs, const Args & ... args)
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{
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boost::format f(fs);
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f.exceptions(boost::io::all_error_bits ^ boost::io::too_many_args_bit);
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formatHelper(f, args...);
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return f.str();
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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 = 1; // exit status
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template<typename... Args>
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BaseError(unsigned int status, const Args & ... args)
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: err(fmt(args...))
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, status(status)
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{
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}
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template<typename... Args>
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BaseError(const Args & ... args)
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: err(fmt(args...))
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{
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}
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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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using superClass::superClass; \
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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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template<typename... Args>
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SysError(const Args & ... args)
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: Error(addErrno(fmt(args...)))
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{ }
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private:
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std::string addErrno(const std::string & s);
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};
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typedef list<string> Strings;
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typedef set<string> StringSet;
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typedef std::map<std::string, std::string> StringMap;
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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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/* Helper class to run code at startup. */
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template<typename T>
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struct OnStartup
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{
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OnStartup(T && t) { t(); }
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};
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}
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