128 lines
2.6 KiB
C++
128 lines
2.6 KiB
C++
#pragma once
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#include <boost/format.hpp>
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#include <string>
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#include "ansicolor.hh"
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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 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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template<class F>
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FormatOrString(const F & 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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template<class F>
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inline void formatHelper(F & f)
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{
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}
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template<class F, typename T, typename... Args>
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inline void formatHelper(F & 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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// -----------------------------------------------------------------------------
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// format function for hints in errors. same as fmt, except templated values
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// are always in yellow.
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template <class T>
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struct yellowify
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{
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yellowify(T &s) : value(s) {}
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T &value;
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};
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template <class T>
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std::ostream& operator<<(std::ostream &out, const yellowify<T> &y)
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{
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return out << ANSI_YELLOW << y.value << ANSI_NORMAL;
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}
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class hintformat
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{
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public:
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hintformat(const string &format) :fmt(format)
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{
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fmt.exceptions(boost::io::all_error_bits ^ boost::io::too_many_args_bit);
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}
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template<class T>
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hintformat& operator%(const T &value)
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{
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fmt % yellowify(value);
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return *this;
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}
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hintformat(const hintformat &hf)
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: fmt(hf.fmt)
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{}
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std::string str() const
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{
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return fmt.str();
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}
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template <typename U>
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friend class AddHint;
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private:
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format fmt;
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};
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std::ostream& operator<<(std::ostream &os, const hintformat &hf);
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template<typename... Args>
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inline hintformat hintfmt(const std::string & fs, const Args & ... args)
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{
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hintformat f(fs);
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formatHelper(f, args...);
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return f;
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}
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}
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