Make "nix-build -A <derivation>.<output>" do the right thing

For example, given a derivation with outputs "out", "man" and "bin":

  $ nix-build -A pkg

produces ./result pointing to the "out" output;

  $ nix-build -A pkg.man

produces ./result-man pointing to the "man" output;

  $ nix-build -A pkg.all

produces ./result, ./result-man and ./result-bin;

  $ nix-build -A pkg.all -A pkg2

produces ./result, ./result-man, ./result-bin and ./result-2.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index e0a4f43c0bb8..1551ae28a81a 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -252,4 +252,21 @@ Hash hashDerivationModulo(StoreAPI & store, Derivation drv)
 }
 
 
+DrvPathWithOutputs parseDrvPathWithOutputs(const string & s)
+{
+    size_t n = s.find("!");
+    return n == s.npos
+        ? DrvPathWithOutputs(s, std::set<string>())
+        : DrvPathWithOutputs(string(s, 0, n), tokenizeString<std::set<string> >(string(s, n + 1), ","));
+}
+
+
+Path makeDrvPathWithOutputs(const Path & drvPath, std::set<string> outputs)
+{
+    return outputs.empty()
+        ? drvPath
+        : drvPath + "!" + concatStringsSep(",", outputs);
+}
+
+
 }