lix/src/libutil/args.hh
2019-02-11 11:55:25 +01:00

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#pragma once
#include <iostream>
#include <map>
#include <memory>
#include "util.hh"
namespace nix {
MakeError(UsageError, Error);
enum HashType : char;
class Args
{
public:
/* Parse the command line, throwing a UsageError if something goes
wrong. */
void parseCmdline(const Strings & cmdline);
virtual void printHelp(const string & programName, std::ostream & out);
virtual std::string description() { return ""; }
protected:
static const size_t ArityAny = std::numeric_limits<size_t>::max();
/* Flags. */
struct Flag
{
typedef std::shared_ptr<Flag> ptr;
std::string longName;
char shortName = 0;
std::string description;
Strings labels;
size_t arity = 0;
std::function<void(std::vector<std::string>)> handler;
std::string category;
};
std::map<std::string, Flag::ptr> longFlags;
std::map<char, Flag::ptr> shortFlags;
virtual bool processFlag(Strings::iterator & pos, Strings::iterator end);
virtual void printFlags(std::ostream & out);
/* Positional arguments. */
struct ExpectedArg
{
std::string label;
size_t arity; // 0 = any
bool optional;
std::function<void(std::vector<std::string>)> handler;
};
std::list<ExpectedArg> expectedArgs;
virtual bool processArgs(const Strings & args, bool finish);
std::set<std::string> hiddenCategories;
public:
class FlagMaker
{
Args & args;
Flag::ptr flag;
friend class Args;
FlagMaker(Args & args) : args(args), flag(std::make_shared<Flag>()) { };
public:
~FlagMaker();
FlagMaker & longName(const std::string & s) { flag->longName = s; return *this; };
FlagMaker & shortName(char s) { flag->shortName = s; return *this; };
FlagMaker & description(const std::string & s) { flag->description = s; return *this; };
FlagMaker & label(const std::string & l) { flag->arity = 1; flag->labels = {l}; return *this; };
FlagMaker & labels(const Strings & ls) { flag->arity = ls.size(); flag->labels = ls; return *this; };
FlagMaker & arity(size_t arity) { flag->arity = arity; return *this; };
FlagMaker & handler(std::function<void(std::vector<std::string>)> handler) { flag->handler = handler; return *this; };
FlagMaker & handler(std::function<void()> handler) { flag->handler = [handler](std::vector<std::string>) { handler(); }; return *this; };
FlagMaker & handler(std::function<void(std::string)> handler) {
flag->arity = 1;
flag->handler = [handler](std::vector<std::string> ss) { handler(std::move(ss[0])); };
return *this;
};
FlagMaker & category(const std::string & s) { flag->category = s; return *this; };
template<class T>
FlagMaker & dest(T * dest)
{
flag->arity = 1;
flag->handler = [=](std::vector<std::string> ss) { *dest = ss[0]; };
return *this;
};
template<class T>
FlagMaker & set(T * dest, const T & val)
{
flag->arity = 0;
flag->handler = [=](std::vector<std::string> ss) { *dest = val; };
return *this;
};
FlagMaker & mkHashTypeFlag(HashType * ht);
};
FlagMaker mkFlag();
/* Helper functions for constructing flags / positional
arguments. */
void mkFlag1(char shortName, const std::string & longName,
const std::string & label, const std::string & description,
std::function<void(std::string)> fun)
{
mkFlag()
.shortName(shortName)
.longName(longName)
.labels({label})
.description(description)
.arity(1)
.handler([=](std::vector<std::string> ss) { fun(ss[0]); });
}
void mkFlag(char shortName, const std::string & name,
const std::string & description, bool * dest)
{
mkFlag(shortName, name, description, dest, true);
}
template<class T>
void mkFlag(char shortName, const std::string & longName, const std::string & description,
T * dest, const T & value)
{
mkFlag()
.shortName(shortName)
.longName(longName)
.description(description)
.handler([=](std::vector<std::string> ss) { *dest = value; });
}
template<class I>
void mkIntFlag(char shortName, const std::string & longName,
const std::string & description, I * dest)
{
mkFlag<I>(shortName, longName, description, [=](I n) {
*dest = n;
});
}
template<class I>
void mkFlag(char shortName, const std::string & longName,
const std::string & description, std::function<void(I)> fun)
{
mkFlag()
.shortName(shortName)
.longName(longName)
.labels({"N"})
.description(description)
.arity(1)
.handler([=](std::vector<std::string> ss) {
I n;
if (!string2Int(ss[0], n))
throw UsageError("flag '--%s' requires a integer argument", longName);
fun(n);
});
}
/* Expect a string argument. */
void expectArg(const std::string & label, string * dest, bool optional = false)
{
expectedArgs.push_back(ExpectedArg{label, 1, optional, [=](std::vector<std::string> ss) {
*dest = ss[0];
}});
}
/* Expect 0 or more arguments. */
void expectArgs(const std::string & label, std::vector<std::string> * dest)
{
expectedArgs.push_back(ExpectedArg{label, 0, false, [=](std::vector<std::string> ss) {
*dest = std::move(ss);
}});
}
friend class MultiCommand;
};
/* A command is an argument parser that can be executed by calling its
run() method. */
struct Command : virtual Args
{
virtual std::string name() = 0;
virtual void prepare() { };
virtual void run() = 0;
struct Example
{
std::string description;
std::string command;
};
typedef std::list<Example> Examples;
virtual Examples examples() { return Examples(); }
void printHelp(const string & programName, std::ostream & out) override;
};
typedef std::map<std::string, ref<Command>> Commands;
/* An argument parser that supports multiple subcommands,
i.e. <command> <subcommand>. */
class MultiCommand : virtual Args
{
public:
Commands commands;
std::shared_ptr<Command> command;
MultiCommand(const std::vector<ref<Command>> & commands);
void printHelp(const string & programName, std::ostream & out) override;
bool processFlag(Strings::iterator & pos, Strings::iterator end) override;
bool processArgs(const Strings & args, bool finish) override;
};
Strings argvToStrings(int argc, char * * argv);
/* Helper function for rendering argument labels. */
std::string renderLabels(const Strings & labels);
/* Helper function for printing 2-column tables. */
typedef std::vector<std::pair<std::string, std::string>> Table2;
void printTable(std::ostream & out, const Table2 & table);
}