lix-releng-staging/src/nix/command.hh
Eelco Dolstra bbe97dff8b Make the Store API more type-safe
Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.

Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.

Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).
2019-12-10 22:06:05 +01:00

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#pragma once
#include "args.hh"
#include "common-eval-args.hh"
#include "path.hh"
namespace nix {
extern std::string programPath;
struct Value;
class Bindings;
class EvalState;
struct Pos;
class Store;
/* A command that requires a Nix store. */
struct StoreCommand : virtual Command
{
StoreCommand();
void run() override;
ref<Store> getStore();
virtual ref<Store> createStore();
virtual void run(ref<Store>) = 0;
private:
std::shared_ptr<Store> _store;
};
struct Buildable
{
std::optional<StorePath> drvPath;
std::map<std::string, StorePath> outputs;
};
typedef std::vector<Buildable> Buildables;
struct Installable
{
virtual ~Installable() { }
virtual std::string what() = 0;
virtual Buildables toBuildables()
{
throw Error("argument '%s' cannot be built", what());
}
Buildable toBuildable();
virtual Value * toValue(EvalState & state)
{
throw Error("argument '%s' cannot be evaluated", what());
}
};
struct SourceExprCommand : virtual Args, StoreCommand, MixEvalArgs
{
Path file;
SourceExprCommand();
/* Return a value representing the Nix expression from which we
are installing. This is either the file specified by --file,
or an attribute set constructed from $NIX_PATH, e.g. { nixpkgs
= import ...; bla = import ...; }. */
Value * getSourceExpr(EvalState & state);
ref<EvalState> getEvalState();
private:
std::shared_ptr<EvalState> evalState;
Value * vSourceExpr = 0;
};
enum RealiseMode { Build, NoBuild, DryRun };
/* A command that operates on a list of "installables", which can be
store paths, attribute paths, Nix expressions, etc. */
struct InstallablesCommand : virtual Args, SourceExprCommand
{
std::vector<std::shared_ptr<Installable>> installables;
InstallablesCommand()
{
expectArgs("installables", &_installables);
}
void prepare() override;
virtual bool useDefaultInstallables() { return true; }
private:
std::vector<std::string> _installables;
};
/* A command that operates on exactly one "installable" */
struct InstallableCommand : virtual Args, SourceExprCommand
{
std::shared_ptr<Installable> installable;
InstallableCommand()
{
expectArg("installable", &_installable);
}
void prepare() override;
private:
std::string _installable;
};
/* A command that operates on zero or more store paths. */
struct StorePathsCommand : public InstallablesCommand
{
private:
bool recursive = false;
bool all = false;
protected:
RealiseMode realiseMode = NoBuild;
public:
StorePathsCommand(bool recursive = false);
using StoreCommand::run;
virtual void run(ref<Store> store, std::vector<StorePath> storePaths) = 0;
void run(ref<Store> store) override;
bool useDefaultInstallables() override { return !all; }
};
/* A command that operates on exactly one store path. */
struct StorePathCommand : public InstallablesCommand
{
using StoreCommand::run;
virtual void run(ref<Store> store, const StorePath & storePath) = 0;
void run(ref<Store> store) override;
};
/* A helper class for registering commands globally. */
struct RegisterCommand
{
static Commands * commands;
RegisterCommand(const std::string & name,
std::function<ref<Command>()> command)
{
if (!commands) commands = new Commands;
commands->emplace(name, command);
}
};
template<class T>
static RegisterCommand registerCommand(const std::string & name)
{
return RegisterCommand(name, [](){ return make_ref<T>(); });
}
std::shared_ptr<Installable> parseInstallable(
SourceExprCommand & cmd, ref<Store> store, const std::string & installable,
bool useDefaultInstallables);
Buildables build(ref<Store> store, RealiseMode mode,
std::vector<std::shared_ptr<Installable>> installables);
std::set<StorePath> toStorePaths(ref<Store> store, RealiseMode mode,
std::vector<std::shared_ptr<Installable>> installables);
StorePath toStorePath(ref<Store> store, RealiseMode mode,
std::shared_ptr<Installable> installable);
std::set<StorePath> toDerivations(ref<Store> store,
std::vector<std::shared_ptr<Installable>> installables,
bool useDeriver = false);
/* Helper function to generate args that invoke $EDITOR on
filename:lineno. */
Strings editorFor(const Pos & pos);
}