wroclaw-git-backups/nix
1
0
Fork 0
mirror of https://github.com/NixOS/nix synced 2025-06-26 11:41:15 +02:00
Code Activity

Make the Derived Path family of types inductive for dynamic derivations

Browse source 
We want to be able to write down `foo.drv^bar.drv^baz`:
`foo.drv^bar.drv` is the dynamic derivation (since it is itself a
derivation output, `bar.drv` from `foo.drv`).

To that end, we create `Single{Derivation,BuiltPath}` types, that are
very similar except instead of having multiple outputs (in a set or
map), they have a single one. This is for everything to the left of the
rightmost `^`.

`NixStringContextElem` has an analogous change, and now can reuse
`SingleDerivedPath` at the top level. In fact, if we ever get rid of
`DrvDeep`, `NixStringContextElem` could be replaced with
`SingleDerivedPath` entirely!

Important note: some JSON formats have changed.

We already can *produce* dynamic derivations, but we can't refer to them
directly. Today, we can merely express building or example at the top
imperatively over time by building `foo.drv^bar.drv`, and then with a
second nix invocation doing `<result-from-first>^baz`, but this is not
declarative. The ethos of Nix of being able to write down the full plan
everything you want to do, and then execute than plan with a single
command, and for that we need the new inductive form of these types.

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This commit is contained in:
John Ericson 2023-01-15 17:39:04 -05:00
parent d00fe5f225
commit 60b7121d2c
48 changed files with 1136 additions and 267 deletions
Download patch file Download diff file Expand all files Collapse all files

47
src/libstore/path-with-outputs.cc
View file

@ -16,10 +16,16 @@ std::string StorePathWithOutputs::to_string(const Store & store) const
DerivedPath StorePathWithOutputs::toDerivedPath() const
{
if (!outputs.empty()) {
return DerivedPath::Built { path, OutputsSpec::Names { outputs } };
return DerivedPath::Built {
.drvPath = makeConstantStorePathRef(path),
.outputs = OutputsSpec::Names { outputs },
};
} else if (path.isDerivation()) {
assert(outputs.empty());
return DerivedPath::Built { path, OutputsSpec::All { } };
return DerivedPath::Built {
.drvPath = makeConstantStorePathRef(path),
.outputs = OutputsSpec::All { },
};
} else {
return DerivedPath::Opaque { path };
}
@ -34,29 +40,36 @@ std::vector<DerivedPath> toDerivedPaths(const std::vector<StorePathWithOutputs>
}
std::variant<StorePathWithOutputs, StorePath> StorePathWithOutputs::tryFromDerivedPath(const DerivedPath & p)
StorePathWithOutputs::ParseResult StorePathWithOutputs::tryFromDerivedPath(const DerivedPath & p)
{
return std::visit(overloaded {
[&](const DerivedPath::Opaque & bo) -> std::variant<StorePathWithOutputs, StorePath> {
[&](const DerivedPath::Opaque & bo) -> StorePathWithOutputs::ParseResult {
if (bo.path.isDerivation()) {
// drv path gets interpreted as "build", not "get drv file itself"
return bo.path;
}
return StorePathWithOutputs { bo.path };
},
[&](const DerivedPath::Built & bfd) -> std::variant<StorePathWithOutputs, StorePath> {
return StorePathWithOutputs {
.path = bfd.drvPath,
// Use legacy encoding of wildcard as empty set
.outputs = std::visit(overloaded {
[&](const OutputsSpec::All &) -> StringSet {
return {};
},
[&](const OutputsSpec::Names & outputs) {
return static_cast<StringSet>(outputs);
},
}, bfd.outputs.raw()),
};
[&](const DerivedPath::Built & bfd) -> StorePathWithOutputs::ParseResult {
return std::visit(overloaded {
[&](const SingleDerivedPath::Opaque & bo) -> StorePathWithOutputs::ParseResult {
return StorePathWithOutputs {
.path = bo.path,
// Use legacy encoding of wildcard as empty set
.outputs = std::visit(overloaded {
[&](const OutputsSpec::All &) -> StringSet {
return {};
},
[&](const OutputsSpec::Names & outputs) {
return static_cast<StringSet>(outputs);
},
}, bfd.outputs.raw()),
};
},
[&](const SingleDerivedPath::Built &) -> StorePathWithOutputs::ParseResult {
return std::monostate {};
},
}, bfd.drvPath->raw());
},
}, p.raw());
}