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Add builtins.appendContext.

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A partner of builtins.getContext, useful for the same reasons.
This commit is contained in:
Shea Levy 2019-01-14 11:34:54 -05:00
parent 1d757292d0
commit b30be6b450
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GPG Key ID: 5C0BD6957D86FE27
2 changed files with 61 additions and 4 deletions
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59
src/libexpr/primops/context.cc
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@ -1,5 +1,6 @@
#include "primops.hh"
#include "eval-inline.hh"
#include "derivations.hh"
namespace nix {
@ -61,8 +62,7 @@ static RegisterPrimOp r3("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscar
(i.e. the kind of context you get when referencing
.outPath of some derivation). Empty list if missing.
Note that for a given path any combination of the above attributes
may be present, but at least one must be set to something other
than the default.
may be present.
*/
static void prim_getContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
@ -129,4 +129,59 @@ static void prim_getContext(EvalState & state, const Pos & pos, Value * * args,
static RegisterPrimOp r4("__getContext", 1, prim_getContext);
/* Append the given context to a given string.
See the commentary above unsafeGetContext for details of the
context representation.
*/
static void prim_appendContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
PathSet context;
auto orig = state.forceString(*args[0], context, pos);
state.forceAttrs(*args[1], pos);
auto sPath = state.symbols.create("path");
auto sAllOutputs = state.symbols.create("allOutputs");
for (auto & i : *args[1]->attrs) {
if (!state.store->isStorePath(i.name))
throw EvalError("Context key '%s' is not a store path, at %s", i.name, i.pos);
if (!settings.readOnlyMode)
state.store->ensurePath(i.name);
state.forceAttrs(*i.value, *i.pos);
auto iter = i.value->attrs->find(sPath);
if (iter != i.value->attrs->end()) {
if (state.forceBool(*iter->value, *iter->pos))
context.insert(i.name);
}
iter = i.value->attrs->find(sAllOutputs);
if (iter != i.value->attrs->end()) {
if (state.forceBool(*iter->value, *iter->pos)) {
if (!isDerivation(i.name)) {
throw EvalError("Tried to add all-outputs context of %s, which is not a derivation, to a string, at %s", i.name, i.pos);
}
context.insert("=" + string(i.name));
}
}
iter = i.value->attrs->find(state.sOutputs);
if (iter != i.value->attrs->end()) {
state.forceList(*iter->value, *iter->pos);
if (iter->value->listSize() && !isDerivation(i.name)) {
throw EvalError("Tried to add derivation output context of %s, which is not a derivation, to a string, at %s", i.name, i.pos);
}
for (unsigned int n = 0; n < iter->value->listSize(); ++n) {
auto name = state.forceStringNoCtx(*iter->value->listElems()[n], *iter->pos);
context.insert("!" + name + "!" + string(i.name));
}
}
}
mkString(v, orig, context);
}
static RegisterPrimOp r5("__appendContext", 2, prim_appendContext);
}

6
tests/lang/eval-okay-context-introspection.nix
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@ -18,5 +18,7 @@ let
};
};
legit-context = "${path}${drv.outPath}${drv.foo.outPath}${drv.drvPath}";
in builtins.getContext legit-context == desired-context
legit-context = builtins.getContext "${path}${drv.outPath}${drv.foo.outPath}${drv.drvPath}";
constructed-context = builtins.getContext (builtins.appendContext "" desired-context);
in legit-context == constructed-context