lix/src/libexpr/common-opts.cc
Eelco Dolstra 62a6eeb1f3 Make the Nix search path declarative
Nix search path lookups like <nixpkgs> are now desugared to ‘findFile
nixPath <nixpkgs>’, where ‘findFile’ is a new primop. Thus you can
override the search path simply by saying

  let
    nixPath = [ { prefix = "nixpkgs"; path = "/my-nixpkgs"; } ];
  in ... <nixpkgs> ...

In conjunction with ‘scopedImport’ (commit
c273c15cb1), the Nix search path can be
propagated across imports, e.g.

  let

    overrides = {
      nixPath = [ ... ] ++ builtins.nixPath;
      import = fn: scopedImport overrides fn;
      scopedImport = attrs: fn: scopedImport (overrides // attrs) fn;
      builtins = builtins // overrides;
    };

  in scopedImport overrides ./nixos
2014-05-26 17:02:22 +02:00

58 lines
1.3 KiB
C++

#include "common-opts.hh"
#include "../libmain/shared.hh"
#include "util.hh"
namespace nix {
bool parseOptionArg(const string & arg, Strings::iterator & i,
const Strings::iterator & argsEnd, EvalState & state,
Bindings & autoArgs)
{
if (arg != "--arg" && arg != "--argstr") return false;
UsageError error(format("`%1%' requires two arguments") % arg);
if (i == argsEnd) throw error;
string name = *i++;
if (i == argsEnd) throw error;
string value = *i++;
/* !!! check for duplicates! */
Value * v = state.allocValue();
autoArgs.push_back(Attr(state.symbols.create(name), v));
if (arg == "--arg")
state.mkThunk_(*v, state.parseExprFromString(value, absPath(".")));
else
mkString(*v, value);
autoArgs.sort(); // !!! inefficient
return true;
}
bool parseSearchPathArg(const string & arg, Strings::iterator & i,
const Strings::iterator & argsEnd, Strings & searchPath)
{
if (arg != "-I") return false;
if (i == argsEnd) throw UsageError(format("`%1%' requires an argument") % arg);;
searchPath.push_back(*i++);
return true;
}
Path lookupFileArg(EvalState & state, string s)
{
if (s.size() > 2 && s.at(0) == '<' && s.at(s.size() - 1) == '>') {
Path p = s.substr(1, s.size() - 2);
return state.findFile(p);
} else
return absPath(s);
}
}