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libexpr: mild cleanup to getDerivations

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Shuffled the logic around a bit so the shorter code paths are early
returns, added comments, etc.

Should be NFC.

Change-Id: Ie3ddb3d0eddd614d6f8c37bf9a4d5a50282084ea
This commit is contained in:
Qyriad 2024-07-07 17:56:14 -06:00
parent 6a30ea0cc4
commit 5ffed6d06a
1 changed files with 81 additions and 42 deletions
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123
src/libexpr/get-drvs.cc
View file

@ -1,6 +1,7 @@
#include "get-drvs.hh"
#include "eval-inline.hh"
#include "derivations.hh"
#include "eval.hh"
#include "store-api.hh"
#include "path-with-outputs.hh"
@ -418,56 +419,94 @@ static void getDerivations(EvalState & state, Value & vIn,
Value v;
state.autoCallFunction(autoArgs, vIn, v);
/* Process the expression. */
if (!getDerivation(state, v, pathPrefix, drvs, ignoreAssertionFailures)) ;
else if (v.type() == nAttrs) {
/* Dont consider sets we've already seen, e.g. y in
`rec { x.d = derivation {...}; y = x; }`. */
if (!done.insert(v.attrs).second) return;
/* !!! undocumented hackery to support combining channels in
nix-env.cc. */
bool combineChannels = v.attrs->find(state.symbols.create("_combineChannels")) != v.attrs->end();
/* Consider the attributes in sorted order to get more
deterministic behaviour in nix-env operations (e.g. when
there are names clashes between derivations, the derivation
bound to the attribute with the "lower" name should take
precedence). */
for (auto & i : v.attrs->lexicographicOrder(state.symbols)) {
debug("evaluating attribute '%1%'", state.symbols[i->name]);
if (!std::regex_match(std::string(state.symbols[i->name]), attrRegex))
continue;
std::string pathPrefix2 = addToPath(pathPrefix, state.symbols[i->name]);
if (combineChannels)
getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
else if (getDerivation(state, *i->value, pathPrefix2, drvs, ignoreAssertionFailures)) {
/* If the value of this attribute is itself a set,
should we recurse into it? => Only if it has a
`recurseForDerivations = true' attribute. */
if (i->value->type() == nAttrs) {
Bindings::iterator j = i->value->attrs->find(state.sRecurseForDerivations);
if (j != i->value->attrs->end() && state.forceBool(*j->value, j->pos, "while evaluating the attribute `recurseForDerivations`"))
getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
}
}
}
bool shouldRecurse = getDerivation(state, v, pathPrefix, drvs, ignoreAssertionFailures);
if (!shouldRecurse) {
// We're done here.
return;
}
else if (v.type() == nList) {
if (v.type() == nList) {
// NOTE we can't really deduplicate here because small lists don't have stable addresses
// and can cause spurious duplicate detections due to v being on the stack.
for (auto [n, elem] : enumerate(v.listItems())) {
std::string pathPrefix2 = addToPath(pathPrefix, fmt("%d", n));
if (getDerivation(state, *elem, pathPrefix2, drvs, ignoreAssertionFailures))
getDerivations(state, *elem, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
std::string joinedAttrPath = addToPath(pathPrefix, fmt("%d", n));
bool shouldRecurse = getDerivation(state, *elem, joinedAttrPath, drvs, ignoreAssertionFailures);
if (shouldRecurse) {
getDerivations(
state,
*elem,
joinedAttrPath,
autoArgs,
drvs,
done,
ignoreAssertionFailures
);
}
}
return;
} else if (v.type() != nAttrs) {
state.error<TypeError>(
"expression does not evaluate to a derivation (or a list or set of those)"
).debugThrow();
}
else
state.error<TypeError>("expression does not evaluate to a derivation (or a set or list of those)").debugThrow();
/* Dont consider sets we've already seen, e.g. y in
`rec { x.d = derivation {...}; y = x; }`. */
auto const &[_, didInsert] = done.insert(v.attrs);
if (!didInsert) {
return;
}
// FIXME: what the fuck???
/* !!! undocumented hackery to support combining channels in
nix-env.cc. */
bool combineChannels = v.attrs->find(state.symbols.create("_combineChannels")) != v.attrs->end();
/* Consider the attributes in sorted order to get more
deterministic behaviour in nix-env operations (e.g. when
there are names clashes between derivations, the derivation
bound to the attribute with the "lower" name should take
precedence). */
for (auto & attr : v.attrs->lexicographicOrder(state.symbols)) {
debug("evaluating attribute '%1%'", state.symbols[attr->name]);
// FIXME: only consider attrs with identifier-like names?? Why???
if (!std::regex_match(std::string(state.symbols[attr->name]), attrRegex)) {
continue;
}
std::string joinedAttrPath = addToPath(pathPrefix, state.symbols[attr->name]);
if (combineChannels) {
getDerivations(state, *attr->value, joinedAttrPath, autoArgs, drvs, done, ignoreAssertionFailures);
} else if (getDerivation(state, *attr->value, joinedAttrPath, drvs, ignoreAssertionFailures)) {
/* If the value of this attribute is itself a set,
should we recurse into it? => Only if it has a
`recurseForDerivations = true' attribute. */
if (attr->value->type() == nAttrs) {
Attr * recurseForDrvs = attr->value->attrs->get(state.sRecurseForDerivations);
if (recurseForDrvs == nullptr) {
continue;
}
bool shouldRecurse = state.forceBool(
*recurseForDrvs->value,
attr->pos,
fmt("while evaluating the '%s' attribute", Magenta("recurseForDerivations"))
);
if (!shouldRecurse) {
continue;
}
getDerivations(
state,
*attr->value,
joinedAttrPath,
autoArgs,
drvs,
done,
ignoreAssertionFailures
);
}
}
}
}